We have all these ideas out there so I thought we would tidy them up before continuing on some new ones. Let’s start with what’s really old is sometimes new again. Various ideas have been coming to me as I have been writing these articles and I thought I would share a few of them.
For those of you who are too young to have missed the Golden era of Ham and CB radio era, I have some bad news for you. Many of the “new” ideas that WiFi AP manufacturers have come up with are the same as CB radio antenna systems from 35 years ago. It’s really funny to see how these ideas are implemented and then manufacturers claim “unique” designs. I had this concept on my roof when I was 15.
The best one is the Wavion design. The directional/omni-directional design concept is actually similar to an antenna called a SuperScanner which used 3 vertical elements in a triangular format. By using a switch inside, you basically decided which one of the antennas is the driven element which makes the 2 vertical elements behind it the reflectors (look up Yagi antenna design). Obviously it’s done electronically within the radio with the Wavion, but it’s interesting to see it being deployed in WiFi.
One of the projects I sort of mentioned in Chapter 10 got me thinking about some other ideas and what’s going to push municipal WiFi deployments even faster. I talked in Chapter 11 about using multiple vendors to complete a project since almost nobody makes a fully universal product line. Motorola is getting there with their new licensed PTP radios but they have made some decisions on the mesh AP side that limit my consideration of them in some of my designs. They have the most wide-ranging product line however but I’m seeing more vendors expanding their product lines.
In Chapter 10 I also mentioned wanting to test a couple ideas in Phoenix that might make the Florida project more cost effective. The costs started going through the roof because each AP needed a pole and electricity. The question that popped in my mind went back to an old design I put into Stratosphere with dual 802.11b radios. I didn’t have 5GHz backhaul yet so we used WDS on the 2.4GHz side and we backhauled 4 APs. I also didn’t have omni-directional antennas since I was shooting straight down a hall. Throw in two more random thoughts and an idea starts forming.
What works better, a 15dBi omni or a 16dBi 120 degree sector antenna? In terms of pure range, the sector antenna obviously beats the omni antenna for a couple reasons (this is where spending hours surfing the different on-line catalogs starts having value). However, we need 360 degree of coverage which means 3 antennas, 3 radios. There are some radios like the Motorola AP7181 which uses a single 2.4GHz and a single 5.8GHz radio that uses an amplifier to feed 3 dual-polarity sector antennas.
Now let’s introduce my favorite car analogy. What accelerates faster to 60mph, 3 Ford Ranger trucks carrying 1000 lbs of dirt or one Ford F-250 carrying 3000lbs of dirt? My money is on the Ford Rangers. Don’t fall asleep on my yet, there really is a sane idea forming here.
In TriadLand, we covered using a single 2.4GHz radio for AP and backhaul for cost reasons. Everybody and their Mom are also using 5.8GHz for backhaul. Most manufacturers are using two 5.8GHz radios to prevent the 1/n problem but even the big boys like Motorola and SkyPilot still use a single 5.8GHz radio. However, one trip to Florida showed me that there needed to be another option to get through the Amazon forest that grows along the street. There is the serious question of whether we could get 5.8GHz to reliably shoot down the street without doing pole gymnastics by adding horizontal arms that move out towards the center of the street. That would add even more to the cost.
I was forced to come up with ways to reduce the cost of the deployment in South Florida because of the pole costs. Before I came up with my mobile idea and gave up on the idea of not using 2.4GHz everywhere, I looked at extending the range of the APs even further but still had no way to get 5.8GHz through the trees. Although it’s on my testing schedule, the end result of this idea was using a three 2.4GHz 802.11n 2x2 MIMO radio combination with three 120 degree dual-polarity sector antennas. The 2.4GHz radios would also handle backhaul down the road. I still avoid the 1/n problem since most hops are 180 degrees apart in relation to surrounding APs. Yes, this is what Motorola and BelAir do so it’s not a unique idea. However, the 16dBi antenna are dual polarity which although the same as Motorola, use 3 radios to feed them. In addition, this idea would also have 4dBi antenna gain (I’m estimating here) which gets added to the client side of the link budget equation.
Since this wasn’t a public access system, bandwidth load wasn’t going to be a problem and the dual-polarity antennas would easily punch through the trees overhanging the street for backhaul. I lose one polarity to the car but that still meant 30-50Mbps to the vehicle which is more than enough. Although it’s a noisy band, I cut down the interference to an omni antenna by 1/3, triple the processor power of the AP, eliminate the 1/n problem, and increase the signal strength between APs and the car. Keep in mind that because of the trees, the noise is reduced from indoor AP’s to the street anyway. If noise continues to be a problem, which I doubt since I’m using dual-polarity, there are other techniques to add up to 6dBi on the path equation and reduce the noise even further. This is a rural environment, not Wall Street.
Another subject that came up was security with police departments. You radio guys are immediately jumping to 4.9GHz and the Police IT guys are thinking there is no way we transporting traffic over any system that has 2.4GHz radios or common infrastructure. I have news, there are so many holes in the NCIC through small towns and limited staff IT departments, that securing one hole in Florida doesn’t secure the hole in California. In one city, I found the traffic cameras that were being monitored on displays in the police dispatch room using public IP addresses and default passwords. I wrote an article in Mission Critical Magazine on security that also covered how our electrical Grid is still unsecured. Unless the justice department or FBI is doing audits at every single terminal and network attached to an NCIC database, you can be reasonably assured that a properly designed wireless system, whether it’s 2.4GHz or 4.9GHz, is going to be far more secure than the police network that is attached to the city infrastructure. Given that some IT people didn’t start their careers until later in life and don’t have a lot of experience, the security of wireless network really isn’t your worst problem.
If you have a choice between 2.4GHz and 4.9GHz, simply look at your budget and quadruple it for ¼ the performance for 4.9GHz over 2.4GHz. All of the cost and performance innovations are being done in 2.4GHz. Because 4.9GHz is a very limited market, the technologies are last generation and there isn’t a lot of financial motive to invest in it. For example, what works better in every environment except for the middle of a major city, 4.9GHz with 33dBm output and 7dBm omni with a 20MHz wide channel or 2.4GHz with 2x2 MIMO 802.11N with a 36dBm EIRP and 5MHz channel? In pure performance, it’s a wash. In terms of cost, the 2.4GHz system will be so much cheaper that there isn’t even a comparison. The 2.4GHz system can also be used with other departments much more cheaply. The only environment where a 4.9GHz system with mobility comes even close to a 2.4GHz system (meaning about 3 times more expensive), assuming you are willing to give up throughput to about ¼ the 2.4GHz system, is if there is little or no vegetation. But what about security?
With a 5MHz channel and dual-polarity in 2.4GHz, security is slightly enhanced, interference is greatly reduced, and range is doubled. VPN tunneling hardware or software from the client to the Firewall would encrypt all data. IPS/IDS would constantly be monitoring for hacking and irregular behavior. Police SSIDs don’t get broadcast while public IP’s are the honeypot and isolated from the police network. A user couldn’t even connect to the AP if done right, let alone try and get through the rest of the system.
But what about using a dual-frequency system like a 2.4GHz and 4.9GHz in the AP or backhaul? Same problem, older technology, and an even higher cost and common backhaul. How about a 2.4GHz AP with multiple SSIDs? In my mind, this is the best compromise the solution. The multiple SSIDs allow VLANs and different security options at the AP and the client. It doesn’t matter what the backhaul is since the traffic is on different subnets at that point anyway. The gateways and firewalls are also different. Traffic is prioritized so public safety has the highest priority over all other traffic.
Let’s get back to making some money. A while back I was approached by a company that wanted to design what they called an air fiber type of structure. They were using 4 redundant loops of 1Gbps radios around the city that could be tapped into with a PTP radio for their clients. This is pretty common within some cities as well as some of my designs. In their case though, this was their business plan. I bring this up to show how TriadLand can be adapted for more than just municipal wireless but in many cases you need the backhaul idea to really make it work. We touched upon the local data center concept and most WISPs utilize something along this line.
Wednesday, August 18, 2010
Sunday, July 18, 2010
Chapter 11 - You can’t fit a Square Peg into a Round Hole
My attention deficit disorder is going nuts so I’m going to veer off Triadland a little bit more. We have defined a reference low-cost system and we clearly discussed the fact it’s definitely not the best system for a public safety mobile environment. So I’m going to call this article the prequel. How do we determine what equipment to use or in other words, what is the best system? Actually, most of them have some unique value depending on the application.
Ok, that’s a copout and allows me to avoid the question. However, there is no easy answer. I’ll go through the process that I use when asked to design a system. Keep in mind there are way more variables than I can cover here. The other thing that is highly important is that you know as many products on the market. I’m not just talking about mesh products, but PTP products, PTMP products, mobile products, virtual IP software, VPN products, antenna designs, etc… In addition to reading and keeping data sheets from everybody, get your hands on and get as much field experience with as many manufacturers as possible.
Almost every design I create involves products from multiple manufacturers. Most designs have some type of budget restraint but every design has some function that has higher priority than others. In some cases, the project was referred to me by a supplier or manufacturer. When that happens, I have a personal obligation to work with their particular product lines. That hasn’t been an issue so far but sometimes it means reaching deep into the product toolbox to find other products that enhance a design. Being vendor agnostic is very important for a consultant.
For example, one manufacturer came to me to help design a PTMP system using their APs. The problem was that they didn’t really have an outdoor product line available yet. They were working on one but in the meantime, they designed a NEMA enclosure and cabling structure that allowed the indoor units to be used outdoors. The basic problem with most indoor units was that the power output on the transmitter is usually underpowered compared to most outdoor units. FCC certifications with the manufacturer antennas were also clearly going to limit the range of the equipment.
In this case, I first had to do a little legwork to understand the rules I was limited by. I then had to analyze in detail, the bandwidth requirements at each location to determine what PTP or PTMP design options I had and what modulation rates I was going to be able to achieve on each link. This was to ensure that I didn’t overload the links. Since this design was going to start with 5.8GHz links, I was going to be limited to MCS rates up to the magical 300Mbps depending on distance. As we discussed in earlier articles MCS(15) rates are hard to get but in reality, I’m not getting more than 80Mbps TCP/IP in one direction. Even that was going to be difficult. The other problem is I didn’t know the APs in terms of actual throughput with video streams so that’s another variable where I have to err on the side of caution. It’s also probably a good idea to know the chipsets the AP manufacturers are using and the FCC AP filing information to review manufacturer data to get the actual facts that aren’t in the brochure.
Given the distances, FCC regulations, bandwidth requirements, and a few other unknowns, it was evident there was no way this equipment was going to be able to handle all the traffic. That’s when the design changes and you have to go to different manufacturers for at least some of the project. The important thing to me is to still use as much as the referring supplier or manufacturers equipment as possible.
For example, let’s say that we have a single primary building connecting to 2 other buildings that are within 30 degrees of each other from the primary building. We will call them A, B, and C. The A building is the primary, the B building is 1 mile away and the C building is 2 miles away.
I have 3 options.
1)One AP with a sector antenna on building A with 1 AP on each of the other 2 buildings with directional panel antennas (maximum gain legally certified antenna) on the other 2 buildings
2)Two APs on building A on different frequencies, one pointing at each of the other 2 buildings
3)One AP on the building A pointing to one AP on the closest building with a second AP then relaying to the farthest building.
Which option depends on how the network is going to be used, which direction is the traffic flowing to, and how much bandwidth do we need through each building. We also have to understand what the modulation rates are going to be at 1 mile links and 2 mile links. There may also be Fresnel zone issues or obstructions between buildings that may limit my options. Keep in mind FCC legal antenna requirements that may not give you enough gain to overcome a bad Fresnel issue. If for example, you used option 2, you may get MSC(15) rates from A to B but MCS (9) rates from A to C. The MCS(9) rates are clearly unacceptable and may come with a higher packet error issue. That might force you into option 3 to keep rates up. At the same time, you have just increased the amount of traffic through the A to B link. It was this type of situation that forced me to design the network using 3 high-bandwidth licensed options and using twenty 5.8GHz APs to feed into these. I used the maximum amount of the referring party’s equipment without compromising the integrity and price model of the design and still met the required specifications of the system. I also created redundant paths using the 5.8GHz radios to connect the entire critical infrastructure. This supported use of additional 5.8GHz APs which were cheaper than the licensed radios for backup.
The other part of this design utilized a technique that seems to becoming more common. Don’t take manufacturers suggested deployment strategies as gospel. There are many different ways to deploy a radio regardless of the original concept. Nothing says that a mesh radio has to be deployed in mesh designs only. Nothing says that a municipal deployment has to be mesh as demonstrated by TriadLand. There are many ways to deploy the various products out there. For example, I used mesh equipment to design a system that really ended up as a 98% PTMP system. The difference was that instead of 10 APs sharing 100Mbps, I ended up with 10 APs sharing 300Mbps. This is a huge difference.
Now I’m going to step into the shoes of some of you who have called me about projects. Let’s pretend I’m Joe IT manager (yes, I’m being sexist but I don’t have time to make this completely gender neutral and it screws up one of my points later) and the City Manager just came to me and said he wants WiFi downtown. He wants to make the city look progressive and it may enhance some of the business opportunities. More business means more taxes, bigger city budgets, and the City Manager’s name on driving this type of project. However, as the IT manager, my experience is in wire line infrastructure and I’ve never installed anything more than a few APs around the building.
To add to the pressure, as much as a successful project makes careers, unsuccessful ones do just the opposite. I know of IT managers that have left cities after municipal projects failed. Therefore, as the IT manager, I have to first make sure I define what the City Manager wants. Do they want ubiquitous coverage through most of the downtown area so that everybody can connect everywhere? Does the city want to charge for the service or offer it for free? Does the city want to offer connectivity to local businesses that may be limited to one incumbent local internet provider? These are just a few of the questions that have to be asked to the City Manager before the project even starts. They need to clearly define the expectations before you take the project even further. It’s kind of hard to hit a target when you don’t know what it is. If it isn’t in writing, I wouldn’t go one step further as there is no way to be successful if I don’t know what the goal is. There is no defined measuring stick. It’s also a good way to let mission creep into the project and you will never hit the final goal.
In most cases, the city manager usually needs some guidance to help define the goals. The goals may not be within the budget range and compromises might have to be made. If you have helped them define the goals, when you have to go back and tell them the budget restraints you will have more support. In other cases, there might be other departments such as city utilities that might have to be involved. Knowing that up front and having a City Manager mediating between departments is very helpful. Let’s just say that although some departments work great together in the best interest of the city, other departments are well, kind of like asking Randy Johnson to let you get a hit.
Once I’ve defined the goals of the system, then you need to start bringing in people that have that level of experience. Some of that may be in-house, some of it will have to be brought in from the outside. This is where the penny-wise and pound foolish idea comes in. It’s also where many of us computer people don’t want to admit to the people around us that we really don’t know everything. This is where thing may start going awry. Having someone with experience who has been through the war of early deployments can save a lot of hassle and expense later.
We all have a bias towards something. Ford Mustang people would rather eat dirt than drive a Chevy Camaro. Apple users would rather give up their latte’s than use a Windows computer. We all gravitate to our comfort zone. It’ also why many companies use attractive salespeople (all you IT guys know exactly what I’m talking about), have promotions, and take many an IT person to lunch to open the door and help create that product loyalty. Once that loyalty is established, it’s hard to get people to change their mind. Try to tell a Cisco person that there may be a better router product for this application and you might as well have asked them to give up their first born. They will look at you like you came from another planet. Obviously I’m stereotyping in the interest of humor but there is a significant amount of truth in there.
Brochures, free demo units, and great advertising shouldn’t be the criteria used for a deployment. It should be what fits for the project. For example, if you only have 1-2 wired connections to a 1 mile square deployment, you are going to have lots of hops. In that case, depending on the design, you really need 2 backhaul radios in an AP to minimize the bandwidth loss. If there is only 1 hop, it’s not that important. That changes though if a radio is a central point with several APs feeding into it. A 100Mbps AP handling 4 other AP chains under full load is limited to 25Mbps per chain. That’s where a 2, 3, or 4 radio backhaul design becomes very important.
If you want indoor coverage, there is a lot of vegetation, high vehicle traffic load, or guaranteed connectivity to even the lowest powered WiFi devices, then you will need a lot of access points to stay within a short distance of the target client. Having fewer APs which have to go farther also mean more noise is picked up since you are capturing a larger area. That also means that lower powered devices will have trouble connecting. Several poor quality connections will also cause the AP to slow down significantly. There is a saying that a happy customer will tell a friend, an unhappy customer will tell 10 friends. In the world of Internet, an unhappy customer may be telling thousands of friends.
Make no mistake, even if the service is free, it’s public and reflects on your city. If you put up a system that does not work correctly for its target client, that’s worse than if you didn’t put up any system at all. People will try to make the system do things it was never designed for and when it fails, they will make that public. For example, the system gets turned on, the local newspaper writes an article, and one guy can’t connect because he has some old, early production 802.11b laptop sitting directly behind his refrigerator in his apartment. That’s the guy who will be posting in the comment in the newspaper under the Internet article how the system doesn’t work and then will be calling City Hall. Forget the 100 people who are using it successfully, you will never hear from them.
All this information and we still haven’t figured out what AP to use. This process is simply to start weeding through which equipment might be used based on goals and design limitations. We didn’t even cover site-lease agreements for private property, insurance issues, Internet Gateway points, security, zoning, and a few other details which can derail a project. Some of this isn’t directly tied to the AP obviously, but it’s a good idea to be working on this parallel to the design. For example, if I find out that none of the electrical poles have power during the day, then my design changes drastically. Instead of a mesh design, I may be looking at a lot of hub and spoke designs with longer range. Either that or I have to find 20 hour battery backup units for each pole. If I need private property, then I have to worry about aesthetics, 24 hour access, etc… Designs can change depending on many factors. However, these factors dictate which equipment is to be used. Get through all that, re-evaluate the checkbook, and then we can figure out which APs to start looking at.
Ok, that’s a copout and allows me to avoid the question. However, there is no easy answer. I’ll go through the process that I use when asked to design a system. Keep in mind there are way more variables than I can cover here. The other thing that is highly important is that you know as many products on the market. I’m not just talking about mesh products, but PTP products, PTMP products, mobile products, virtual IP software, VPN products, antenna designs, etc… In addition to reading and keeping data sheets from everybody, get your hands on and get as much field experience with as many manufacturers as possible.
Almost every design I create involves products from multiple manufacturers. Most designs have some type of budget restraint but every design has some function that has higher priority than others. In some cases, the project was referred to me by a supplier or manufacturer. When that happens, I have a personal obligation to work with their particular product lines. That hasn’t been an issue so far but sometimes it means reaching deep into the product toolbox to find other products that enhance a design. Being vendor agnostic is very important for a consultant.
For example, one manufacturer came to me to help design a PTMP system using their APs. The problem was that they didn’t really have an outdoor product line available yet. They were working on one but in the meantime, they designed a NEMA enclosure and cabling structure that allowed the indoor units to be used outdoors. The basic problem with most indoor units was that the power output on the transmitter is usually underpowered compared to most outdoor units. FCC certifications with the manufacturer antennas were also clearly going to limit the range of the equipment.
In this case, I first had to do a little legwork to understand the rules I was limited by. I then had to analyze in detail, the bandwidth requirements at each location to determine what PTP or PTMP design options I had and what modulation rates I was going to be able to achieve on each link. This was to ensure that I didn’t overload the links. Since this design was going to start with 5.8GHz links, I was going to be limited to MCS rates up to the magical 300Mbps depending on distance. As we discussed in earlier articles MCS(15) rates are hard to get but in reality, I’m not getting more than 80Mbps TCP/IP in one direction. Even that was going to be difficult. The other problem is I didn’t know the APs in terms of actual throughput with video streams so that’s another variable where I have to err on the side of caution. It’s also probably a good idea to know the chipsets the AP manufacturers are using and the FCC AP filing information to review manufacturer data to get the actual facts that aren’t in the brochure.
Given the distances, FCC regulations, bandwidth requirements, and a few other unknowns, it was evident there was no way this equipment was going to be able to handle all the traffic. That’s when the design changes and you have to go to different manufacturers for at least some of the project. The important thing to me is to still use as much as the referring supplier or manufacturers equipment as possible.
For example, let’s say that we have a single primary building connecting to 2 other buildings that are within 30 degrees of each other from the primary building. We will call them A, B, and C. The A building is the primary, the B building is 1 mile away and the C building is 2 miles away.
I have 3 options.
1)One AP with a sector antenna on building A with 1 AP on each of the other 2 buildings with directional panel antennas (maximum gain legally certified antenna) on the other 2 buildings
2)Two APs on building A on different frequencies, one pointing at each of the other 2 buildings
3)One AP on the building A pointing to one AP on the closest building with a second AP then relaying to the farthest building.
Which option depends on how the network is going to be used, which direction is the traffic flowing to, and how much bandwidth do we need through each building. We also have to understand what the modulation rates are going to be at 1 mile links and 2 mile links. There may also be Fresnel zone issues or obstructions between buildings that may limit my options. Keep in mind FCC legal antenna requirements that may not give you enough gain to overcome a bad Fresnel issue. If for example, you used option 2, you may get MSC(15) rates from A to B but MCS (9) rates from A to C. The MCS(9) rates are clearly unacceptable and may come with a higher packet error issue. That might force you into option 3 to keep rates up. At the same time, you have just increased the amount of traffic through the A to B link. It was this type of situation that forced me to design the network using 3 high-bandwidth licensed options and using twenty 5.8GHz APs to feed into these. I used the maximum amount of the referring party’s equipment without compromising the integrity and price model of the design and still met the required specifications of the system. I also created redundant paths using the 5.8GHz radios to connect the entire critical infrastructure. This supported use of additional 5.8GHz APs which were cheaper than the licensed radios for backup.
The other part of this design utilized a technique that seems to becoming more common. Don’t take manufacturers suggested deployment strategies as gospel. There are many different ways to deploy a radio regardless of the original concept. Nothing says that a mesh radio has to be deployed in mesh designs only. Nothing says that a municipal deployment has to be mesh as demonstrated by TriadLand. There are many ways to deploy the various products out there. For example, I used mesh equipment to design a system that really ended up as a 98% PTMP system. The difference was that instead of 10 APs sharing 100Mbps, I ended up with 10 APs sharing 300Mbps. This is a huge difference.
Now I’m going to step into the shoes of some of you who have called me about projects. Let’s pretend I’m Joe IT manager (yes, I’m being sexist but I don’t have time to make this completely gender neutral and it screws up one of my points later) and the City Manager just came to me and said he wants WiFi downtown. He wants to make the city look progressive and it may enhance some of the business opportunities. More business means more taxes, bigger city budgets, and the City Manager’s name on driving this type of project. However, as the IT manager, my experience is in wire line infrastructure and I’ve never installed anything more than a few APs around the building.
To add to the pressure, as much as a successful project makes careers, unsuccessful ones do just the opposite. I know of IT managers that have left cities after municipal projects failed. Therefore, as the IT manager, I have to first make sure I define what the City Manager wants. Do they want ubiquitous coverage through most of the downtown area so that everybody can connect everywhere? Does the city want to charge for the service or offer it for free? Does the city want to offer connectivity to local businesses that may be limited to one incumbent local internet provider? These are just a few of the questions that have to be asked to the City Manager before the project even starts. They need to clearly define the expectations before you take the project even further. It’s kind of hard to hit a target when you don’t know what it is. If it isn’t in writing, I wouldn’t go one step further as there is no way to be successful if I don’t know what the goal is. There is no defined measuring stick. It’s also a good way to let mission creep into the project and you will never hit the final goal.
In most cases, the city manager usually needs some guidance to help define the goals. The goals may not be within the budget range and compromises might have to be made. If you have helped them define the goals, when you have to go back and tell them the budget restraints you will have more support. In other cases, there might be other departments such as city utilities that might have to be involved. Knowing that up front and having a City Manager mediating between departments is very helpful. Let’s just say that although some departments work great together in the best interest of the city, other departments are well, kind of like asking Randy Johnson to let you get a hit.
Once I’ve defined the goals of the system, then you need to start bringing in people that have that level of experience. Some of that may be in-house, some of it will have to be brought in from the outside. This is where the penny-wise and pound foolish idea comes in. It’s also where many of us computer people don’t want to admit to the people around us that we really don’t know everything. This is where thing may start going awry. Having someone with experience who has been through the war of early deployments can save a lot of hassle and expense later.
We all have a bias towards something. Ford Mustang people would rather eat dirt than drive a Chevy Camaro. Apple users would rather give up their latte’s than use a Windows computer. We all gravitate to our comfort zone. It’ also why many companies use attractive salespeople (all you IT guys know exactly what I’m talking about), have promotions, and take many an IT person to lunch to open the door and help create that product loyalty. Once that loyalty is established, it’s hard to get people to change their mind. Try to tell a Cisco person that there may be a better router product for this application and you might as well have asked them to give up their first born. They will look at you like you came from another planet. Obviously I’m stereotyping in the interest of humor but there is a significant amount of truth in there.
Brochures, free demo units, and great advertising shouldn’t be the criteria used for a deployment. It should be what fits for the project. For example, if you only have 1-2 wired connections to a 1 mile square deployment, you are going to have lots of hops. In that case, depending on the design, you really need 2 backhaul radios in an AP to minimize the bandwidth loss. If there is only 1 hop, it’s not that important. That changes though if a radio is a central point with several APs feeding into it. A 100Mbps AP handling 4 other AP chains under full load is limited to 25Mbps per chain. That’s where a 2, 3, or 4 radio backhaul design becomes very important.
If you want indoor coverage, there is a lot of vegetation, high vehicle traffic load, or guaranteed connectivity to even the lowest powered WiFi devices, then you will need a lot of access points to stay within a short distance of the target client. Having fewer APs which have to go farther also mean more noise is picked up since you are capturing a larger area. That also means that lower powered devices will have trouble connecting. Several poor quality connections will also cause the AP to slow down significantly. There is a saying that a happy customer will tell a friend, an unhappy customer will tell 10 friends. In the world of Internet, an unhappy customer may be telling thousands of friends.
Make no mistake, even if the service is free, it’s public and reflects on your city. If you put up a system that does not work correctly for its target client, that’s worse than if you didn’t put up any system at all. People will try to make the system do things it was never designed for and when it fails, they will make that public. For example, the system gets turned on, the local newspaper writes an article, and one guy can’t connect because he has some old, early production 802.11b laptop sitting directly behind his refrigerator in his apartment. That’s the guy who will be posting in the comment in the newspaper under the Internet article how the system doesn’t work and then will be calling City Hall. Forget the 100 people who are using it successfully, you will never hear from them.
All this information and we still haven’t figured out what AP to use. This process is simply to start weeding through which equipment might be used based on goals and design limitations. We didn’t even cover site-lease agreements for private property, insurance issues, Internet Gateway points, security, zoning, and a few other details which can derail a project. Some of this isn’t directly tied to the AP obviously, but it’s a good idea to be working on this parallel to the design. For example, if I find out that none of the electrical poles have power during the day, then my design changes drastically. Instead of a mesh design, I may be looking at a lot of hub and spoke designs with longer range. Either that or I have to find 20 hour battery backup units for each pole. If I need private property, then I have to worry about aesthetics, 24 hour access, etc… Designs can change depending on many factors. However, these factors dictate which equipment is to be used. Get through all that, re-evaluate the checkbook, and then we can figure out which APs to start looking at.
Monday, July 5, 2010
Chapter 9: I’m from the Government, I’m here to help you
Now let’s talk about the real-world in deploying this type of system. Realistically, light poles or traffic lights are the obvious deployment locations. They are usually spaced pretty optimally. The problem is they are either owned or operated by the local municipality or the local power company which in many cases, is overseen by a local governing board. Either way, the key word here is government.
I have dealt with municipalities that are both easy to work with and others that are very difficult to work with. It always comes down to the individuals within the departments. However, it also always takes a consensus of staff or departments to get a project through. The ability to get a project passed goes down as more people are required to make a decision and the more money the department has to expend. So getting approval to use municipal facilities generally takes a pretty long time, especially if involves the budgetary cycle.
Now you have to throw in the legalities of a deployment. You need some type of site lease for any facilities you are mounting equipment on. In addition, you might also need insurance in case something gets damaged. We have been required to carry a $2 million dollar policy for some locations. If you have to deal with property owners for buildings, the contracts get more complicated as there is the issue of sale of the building, acess, etc… Even though technically Triadland looks pretty easy, the devil is in the details.
When you go back to build financials for a deployment and you start adding in all the back end costs, you can see that unless you are expecting a lot of paying users, in the thousands, that a multi-million dollar Capex is going to kill the project unless you accurately predict the costs. If you are utilizing a lot of vertical assets, such as some of the models using 60 APs per square mile, and you have to pay for the rights to each of these poles with fees such as $10 per month per pole, then the monthly nut goes way up. Of course knowing you need 60 APs up front instead of thinking you need 30 APs and then later finding out you really needed 60 to begin with is far worse. The days of building a system and the users will come went away with the cell phone companies providing better bandwidth options. Although even Apple knows that WiFi can provide the bandwidth it needs for video applications, the cost and difficulty of managing a few towers versus thousands of APs makes it a no-brainer for cellular providers.
Although some of the cable companies have moved into the WiFi area with hot-spots to enhance their security, it’s not really a national standard for a business model. There is even discussion of cellular companies paying WiFi providers for access to their network. However, it’s evident that although WiFi has high-bandwidth capacity, defining the target client is key to profitability unless Verizon throws some petty cash your way.
As with any good business plan, in complete contrast to former companies that have failed in high-profile examples, the key is keeping Capex down, keeping monthly expenses down, providing a good quality service to retain and add clients, defining a realistic revenue stream, defining system expectations, and making sure you have control of as many facets of the product environment as possible. Sometimes this results in compromises in technical capabilities to balance out profitability and success. Building a system that costs $10,000 per square mile but generates $3000 per month in revenue with a $1000 per month of expenses is far better than building a $100,000 per square mile system that generates $6000 per month in revenue and costs $5,000 per month to support (keep in mind the cost of money needed to build out the system and manufacturer warranty costs) is not a better deal. There is nothing wrong with saying we can’t give 100% indoor coverage if 40% makes it profitable and 80% indoor coverage makes it unprofitable. If the system fails financially, it’s irrelevant what percentage gets covered.
I bring these examples up to show that it takes different designs for success in different applications. Although the industry idea of a municipal wireless system has traditionally been stick APs up every few hundred feet and build a system that is everything to everybody, the best design is the one that is self-sustaining financially which motivates the operator to keep it running.
Municipal Wireless by definition used to mean 100% coverage everywhere, similar to cell phones, with a universal product that was everything to everybody. We need to redefine it so that Municipal Wireless means any 802.11 service protocol deployed in a Wide Area model to provide bandwidth using a unique methodology that can’t be provided by existing cellular or satellite models. Start there and we have a whole new set of opportunities. Throw in 802.11N, MIMO, new 3.65GHz and 900MHz equipment, very low cost wireless equipment, and the possibilities are endless.
Instead of going to a municipality and asking them to be an anchor tenant, why not ask them to pay $10 per month to place a camera on your network or even better, you own the camera and lease viewing time to the city. It’s far easier for the police department and water department to find the funding to pay $100 a month for access to your camera than to Capex $1000 for a camera. Not only is the source of the funding different meaning different rules for purchasing, it also relieves them of hardware obsolescence, technical support costs, and internal training. Expand this idea out to other areas as well.
Many governmental departments are paying $40-$60 per month for cellular data cards. I can tell you for a fact that they are a mixed blessing. The lower bandwidth doesn’t work well for video uplinks. There are dead spots or areas where many of the systems slow down to lower rates and in many smaller cities, they are limited to 100K or less systems. Yes I know LTE and Wimax are here in many cities but try uploading a 3-6Mbps video stream and tell me how that works. Put up a system that can provide better outdoor coverage and they would gladly pay you instead of Verizon or Sprint. Assuming you have outdoor coverage taken care of to the vehicle, you don’t need laptop coverage everywhere because in reality, the city vehicle is a mobile hotspot itself. Use 2 AP’s in the car, $200 instead of $100, and you have a mobile hotspot with about 200’-400’ of coverage around the car. For improved performance in a mobile environment, a dedicated router product such as a Peplink Mobile Max or CarFi, or something similar might be better. I like the Peplink Mobile Max product because it has a load-balancing hardware VPN tunneling feature coming out for secured communications. In mission critical environments, I’ve even looked at using 2.4GHz and 900MHz in the same car simultaneously.
I know that it’s hard to get rid of the old ways. There are lots of manufacturers still building the same equipment they sold 5 years ago with minor changes to support 802.11N. Unfortunately, not even all of them have the ability or design to upgrade to 802.11N. The AP manufacturers need to figure out how to build a product that can make a deployment profitable if they want to get back into that market. If municipalities are the only clients, there is a limited market for too many manufacturers. What is needed is a model where private venture capitalists, many of whom have already been burned, see a business model that is not based on advertising, but based on reasonable costs and has solid income potential. It can’t be based on the idea that government officials are needed to make a business viable. We as consultants need to suggest that manufacturers get entry level prices way down, find additional sources of WISP revenue, and create an expectancy of profitability to drive the market. The manufacturer who does that will own the market.
I have dealt with municipalities that are both easy to work with and others that are very difficult to work with. It always comes down to the individuals within the departments. However, it also always takes a consensus of staff or departments to get a project through. The ability to get a project passed goes down as more people are required to make a decision and the more money the department has to expend. So getting approval to use municipal facilities generally takes a pretty long time, especially if involves the budgetary cycle.
Now you have to throw in the legalities of a deployment. You need some type of site lease for any facilities you are mounting equipment on. In addition, you might also need insurance in case something gets damaged. We have been required to carry a $2 million dollar policy for some locations. If you have to deal with property owners for buildings, the contracts get more complicated as there is the issue of sale of the building, acess, etc… Even though technically Triadland looks pretty easy, the devil is in the details.
When you go back to build financials for a deployment and you start adding in all the back end costs, you can see that unless you are expecting a lot of paying users, in the thousands, that a multi-million dollar Capex is going to kill the project unless you accurately predict the costs. If you are utilizing a lot of vertical assets, such as some of the models using 60 APs per square mile, and you have to pay for the rights to each of these poles with fees such as $10 per month per pole, then the monthly nut goes way up. Of course knowing you need 60 APs up front instead of thinking you need 30 APs and then later finding out you really needed 60 to begin with is far worse. The days of building a system and the users will come went away with the cell phone companies providing better bandwidth options. Although even Apple knows that WiFi can provide the bandwidth it needs for video applications, the cost and difficulty of managing a few towers versus thousands of APs makes it a no-brainer for cellular providers.
Although some of the cable companies have moved into the WiFi area with hot-spots to enhance their security, it’s not really a national standard for a business model. There is even discussion of cellular companies paying WiFi providers for access to their network. However, it’s evident that although WiFi has high-bandwidth capacity, defining the target client is key to profitability unless Verizon throws some petty cash your way.
As with any good business plan, in complete contrast to former companies that have failed in high-profile examples, the key is keeping Capex down, keeping monthly expenses down, providing a good quality service to retain and add clients, defining a realistic revenue stream, defining system expectations, and making sure you have control of as many facets of the product environment as possible. Sometimes this results in compromises in technical capabilities to balance out profitability and success. Building a system that costs $10,000 per square mile but generates $3000 per month in revenue with a $1000 per month of expenses is far better than building a $100,000 per square mile system that generates $6000 per month in revenue and costs $5,000 per month to support (keep in mind the cost of money needed to build out the system and manufacturer warranty costs) is not a better deal. There is nothing wrong with saying we can’t give 100% indoor coverage if 40% makes it profitable and 80% indoor coverage makes it unprofitable. If the system fails financially, it’s irrelevant what percentage gets covered.
I bring these examples up to show that it takes different designs for success in different applications. Although the industry idea of a municipal wireless system has traditionally been stick APs up every few hundred feet and build a system that is everything to everybody, the best design is the one that is self-sustaining financially which motivates the operator to keep it running.
Municipal Wireless by definition used to mean 100% coverage everywhere, similar to cell phones, with a universal product that was everything to everybody. We need to redefine it so that Municipal Wireless means any 802.11 service protocol deployed in a Wide Area model to provide bandwidth using a unique methodology that can’t be provided by existing cellular or satellite models. Start there and we have a whole new set of opportunities. Throw in 802.11N, MIMO, new 3.65GHz and 900MHz equipment, very low cost wireless equipment, and the possibilities are endless.
Instead of going to a municipality and asking them to be an anchor tenant, why not ask them to pay $10 per month to place a camera on your network or even better, you own the camera and lease viewing time to the city. It’s far easier for the police department and water department to find the funding to pay $100 a month for access to your camera than to Capex $1000 for a camera. Not only is the source of the funding different meaning different rules for purchasing, it also relieves them of hardware obsolescence, technical support costs, and internal training. Expand this idea out to other areas as well.
Many governmental departments are paying $40-$60 per month for cellular data cards. I can tell you for a fact that they are a mixed blessing. The lower bandwidth doesn’t work well for video uplinks. There are dead spots or areas where many of the systems slow down to lower rates and in many smaller cities, they are limited to 100K or less systems. Yes I know LTE and Wimax are here in many cities but try uploading a 3-6Mbps video stream and tell me how that works. Put up a system that can provide better outdoor coverage and they would gladly pay you instead of Verizon or Sprint. Assuming you have outdoor coverage taken care of to the vehicle, you don’t need laptop coverage everywhere because in reality, the city vehicle is a mobile hotspot itself. Use 2 AP’s in the car, $200 instead of $100, and you have a mobile hotspot with about 200’-400’ of coverage around the car. For improved performance in a mobile environment, a dedicated router product such as a Peplink Mobile Max or CarFi, or something similar might be better. I like the Peplink Mobile Max product because it has a load-balancing hardware VPN tunneling feature coming out for secured communications. In mission critical environments, I’ve even looked at using 2.4GHz and 900MHz in the same car simultaneously.
I know that it’s hard to get rid of the old ways. There are lots of manufacturers still building the same equipment they sold 5 years ago with minor changes to support 802.11N. Unfortunately, not even all of them have the ability or design to upgrade to 802.11N. The AP manufacturers need to figure out how to build a product that can make a deployment profitable if they want to get back into that market. If municipalities are the only clients, there is a limited market for too many manufacturers. What is needed is a model where private venture capitalists, many of whom have already been burned, see a business model that is not based on advertising, but based on reasonable costs and has solid income potential. It can’t be based on the idea that government officials are needed to make a business viable. We as consultants need to suggest that manufacturers get entry level prices way down, find additional sources of WISP revenue, and create an expectancy of profitability to drive the market. The manufacturer who does that will own the market.
Friday, June 18, 2010
Chapter 8 – Half of Something is Better than Nothing, but Why Settle?
Our network is pretty inexpensive but suffers from first generation bandwidth problems of losing ½ the bandwidth capacity every hop. Patton wouldn’t settle for a partial victory and neither will we since we can do it for very little additional cost. It’s possible to virtually eliminate bandwidth loss per AP for up to $400 for the Gateway points ($100 for every direction it has to backhaul) $200 for midpoints and $100 for the end point. Keep in mind you don’t need to do this at every AP, just the links that have a higher load or to extend the network further. This is also something that can easily be added later as capacity increases.
We currently have the AP cost at about $200 and each AP can handle 30-50Mbps of traffic. However, 2 hops down from the gateway point or backhaul point, we are now down to about ½ of that. Go another hop and its ¼ of that using single radio WDS functionality. WDS has 3 other problems that we can’t get around with Ubiquiti’s Bullet 2M HP’s. The first is that we lose the client isolation function. The second is we lose a proprietary function that we will later cover called AirMax. The third is that we lose advance WPA encryption methods and we are limited to the evermore useless WEP. It’s easy to get around this though. Keep in mind the motto, “it’s not a problem if it can be fixed with money”.
Ubiquiti sells a little radio called a Nanostation Loco M5. It’s available in both 2.4GHz and 5.8GHz versions. We will focus on the 5.8GHz version since that limits the interference for our backhaul and as we discuss later, opens up new options for our network for PTMP. This little fellow only costs $70 and provides a 2x2 MIMO signal that can support up a total of around 100Mbps of total throughput with a 20MHz channel. I’m going a little conservative on throughput numbers since different types of IP traffic can test between 60-150Mbps. Put 2 of them on the pole with the Bullet M2 and your backhaul can now support all that bandwidth across several hops with a loss of about 1Mbps and about 2-3ms of latency added on each hop. However, you have just added another $200 per AP to do this with a switch. If you have two 5.8GHz radios on the pole along with the Bullet, you will need a switch.
The most cost effective switch I have found that is designed to handle reasonable temperatures is the Linksys SD205 unit. Although they are rated for 122 degrees, I have never seen one fail and I have had them in temperatures far in excess of 140 degrees for years. For around $25, they are the best little units for sealed outdoor installations and there is an SD-208 version if you need more ports. Compared to an industrial switch which starts at $250 (cheapest ones I have seen), the Linksys units are a steal. If you need a managed switch, then you are looking at industrial switches and the cost is going to start around $450.
The other good part of adding the Nanostation Loco M5 to our system is now if we have to add more AP’s in the middle of our network, we don’t have worry about the 1/n issue. We can also use WPA or AES security on the 2.4GHz network and 5.8GHz backhaul hops. This solves the wireless security issue. If we have to go around corners or Y off an AP, we can add up to 4 Nanostation Loco M5’s per pole if we use a 20MHz wide channel. Yes, I know that theoretically you can do 5 channels but that leaves no buffer between channels. With 4 channels, you get a 5MHz buffer which although not ideal, it’s not bad.
The drawback to the Nanostation Loco M5 is that to get maximum throughput or MCS (15) rates, you will be limited to 17dBm output with a 13dBm antenna or a total of 30dBm EIRP. If there are any tree obstructions or you need more power, the big brother, the Nanostation M5 has a 16dbi antenna and 21dBm of output for an extra $20. Keep in mind that these radios will go to a much higher power level if necessary but it comes at a reduction in throughput which we discussed in article 2. It does however, leave some room for increasing power if interference or obstructions start to cause issues later.
The Nanostation Loco M5 radios can also do one other thing. If we get back to the idea of a PTMP hybrid system, that means that users that are within the beam pattern of the Nanostation Loco M5’s can actually connect directly to the 5.8GHz backhaul. I suggest this stay reserved for truck rolls and trained technicians. 5.8GHz is a lot more sensitive to LOS which makes it more difficult for clients to install themselves. We are going to extend this concept further later also.
If the goal is that clients are going to install their own CPE’s, either indoors or out, it’s best if clients use a 2.4GHz product, preferably a Nanostation 2M or the upcoming Nanostation Loco 2M for indoor use with a window/wall mount. There is also some new indoor equipment from Ubiquiti, the WiFiStation, with directional and omni-directional antennas that support 802.11N and only cost around $30. The range is obviously lower but it also lowers the cost for clients.
Although our network also doesn’t support 2x2 MIMO on 2.4GHz yet, it is now supporting it on 5.8GHz so things are moving along. We have a couple options coming upon the 2.4GHz 2x2 MIMO solution coming up. There is also a way to customize the firmware on these units so that the CPE can be fixed only on your network with the proper settings and would allow you access to manage settings on the client side to optimize their connection quality. Imagine the client connecting to the system and then you get to remotely upgrade firmware on every client device simultaneously, monitor their connection quality, and manage the connection all way to the computer. That is the advantage to having all the radios from a single vendor. Tech support calls would go way down and staff wouldn’t have to fudge their way through 100 different products. Taking this a step further, if all the devices were Ubiquiti M series radios, you could also use the AirMax feature with polling for the clients. Of course, you sort of kiss off the legacy devices, or do you?
We currently have the AP cost at about $200 and each AP can handle 30-50Mbps of traffic. However, 2 hops down from the gateway point or backhaul point, we are now down to about ½ of that. Go another hop and its ¼ of that using single radio WDS functionality. WDS has 3 other problems that we can’t get around with Ubiquiti’s Bullet 2M HP’s. The first is that we lose the client isolation function. The second is we lose a proprietary function that we will later cover called AirMax. The third is that we lose advance WPA encryption methods and we are limited to the evermore useless WEP. It’s easy to get around this though. Keep in mind the motto, “it’s not a problem if it can be fixed with money”.
Ubiquiti sells a little radio called a Nanostation Loco M5. It’s available in both 2.4GHz and 5.8GHz versions. We will focus on the 5.8GHz version since that limits the interference for our backhaul and as we discuss later, opens up new options for our network for PTMP. This little fellow only costs $70 and provides a 2x2 MIMO signal that can support up a total of around 100Mbps of total throughput with a 20MHz channel. I’m going a little conservative on throughput numbers since different types of IP traffic can test between 60-150Mbps. Put 2 of them on the pole with the Bullet M2 and your backhaul can now support all that bandwidth across several hops with a loss of about 1Mbps and about 2-3ms of latency added on each hop. However, you have just added another $200 per AP to do this with a switch. If you have two 5.8GHz radios on the pole along with the Bullet, you will need a switch.
The most cost effective switch I have found that is designed to handle reasonable temperatures is the Linksys SD205 unit. Although they are rated for 122 degrees, I have never seen one fail and I have had them in temperatures far in excess of 140 degrees for years. For around $25, they are the best little units for sealed outdoor installations and there is an SD-208 version if you need more ports. Compared to an industrial switch which starts at $250 (cheapest ones I have seen), the Linksys units are a steal. If you need a managed switch, then you are looking at industrial switches and the cost is going to start around $450.
The other good part of adding the Nanostation Loco M5 to our system is now if we have to add more AP’s in the middle of our network, we don’t have worry about the 1/n issue. We can also use WPA or AES security on the 2.4GHz network and 5.8GHz backhaul hops. This solves the wireless security issue. If we have to go around corners or Y off an AP, we can add up to 4 Nanostation Loco M5’s per pole if we use a 20MHz wide channel. Yes, I know that theoretically you can do 5 channels but that leaves no buffer between channels. With 4 channels, you get a 5MHz buffer which although not ideal, it’s not bad.
The drawback to the Nanostation Loco M5 is that to get maximum throughput or MCS (15) rates, you will be limited to 17dBm output with a 13dBm antenna or a total of 30dBm EIRP. If there are any tree obstructions or you need more power, the big brother, the Nanostation M5 has a 16dbi antenna and 21dBm of output for an extra $20. Keep in mind that these radios will go to a much higher power level if necessary but it comes at a reduction in throughput which we discussed in article 2. It does however, leave some room for increasing power if interference or obstructions start to cause issues later.
The Nanostation Loco M5 radios can also do one other thing. If we get back to the idea of a PTMP hybrid system, that means that users that are within the beam pattern of the Nanostation Loco M5’s can actually connect directly to the 5.8GHz backhaul. I suggest this stay reserved for truck rolls and trained technicians. 5.8GHz is a lot more sensitive to LOS which makes it more difficult for clients to install themselves. We are going to extend this concept further later also.
If the goal is that clients are going to install their own CPE’s, either indoors or out, it’s best if clients use a 2.4GHz product, preferably a Nanostation 2M or the upcoming Nanostation Loco 2M for indoor use with a window/wall mount. There is also some new indoor equipment from Ubiquiti, the WiFiStation, with directional and omni-directional antennas that support 802.11N and only cost around $30. The range is obviously lower but it also lowers the cost for clients.
Although our network also doesn’t support 2x2 MIMO on 2.4GHz yet, it is now supporting it on 5.8GHz so things are moving along. We have a couple options coming upon the 2.4GHz 2x2 MIMO solution coming up. There is also a way to customize the firmware on these units so that the CPE can be fixed only on your network with the proper settings and would allow you access to manage settings on the client side to optimize their connection quality. Imagine the client connecting to the system and then you get to remotely upgrade firmware on every client device simultaneously, monitor their connection quality, and manage the connection all way to the computer. That is the advantage to having all the radios from a single vendor. Tech support calls would go way down and staff wouldn’t have to fudge their way through 100 different products. Taking this a step further, if all the devices were Ubiquiti M series radios, you could also use the AirMax feature with polling for the clients. Of course, you sort of kiss off the legacy devices, or do you?
Tuesday, June 15, 2010
Chapter 7 – One Size Does Not Fit All
Before we continue developing the system further, I think it’s a good idea to discuss all the various antenna designs that go into a municipal design process. I’ve described one type of design with omni-directional antennas, although I use many difference designs customized to the target client. It won’t meet all needs; no system will unless the budget is unlimited. It is being designed to be as flexible as possible, but there are specific technologies that may work better in some areas. Wireless hardware manufacturers have put forth various designs and optimized their hardware towards that goal. Budgets have sometimes dictated other designs such as “Tales from the Towers.” Due to new equipment that has been released, the numbers of potential designs that can be deployed have exploded.
Let’s start with the legacy systems that started the whole muni-wireless market. The most basic APs were single radios with a single, or dual, omnidirectional antenna design. These systems covered a fixed area and then simultaneously handled backhaul to the next radio. The first problem with this design was simply the fact bandwidth drops by ½ every hop. Although they also supported diversity for the antennas, that didn’t significantly increase the range. It did reduce fading since 802.11b wasn’t really created with a multipath environment in mind.
Eventually, manufacturers went to 802.11g and started adding 2-3 or more radios with secondary radios for backhaul. Using 5GHz frequencies to hand off the backhaul functions increased user throughput, and with dual 5GHz radios, the multi-hop bandwidth loss problem was effectively eliminated. The multi-radio design also spawned some extremely unique AP designs. Manufacturers started adding directional antennas, multiple frequency coverage, integrated sector antennas, beam-forming, and a few other ideas that don’t pass the smell test for actual performance advantages. However, the reason that there are so many systems out there is that there is an actual need for different features. I have used, and will continue to use, many of these products because of their uniqueness.
Jump forward to post-802.11N MIMO technologies, and the number of options from both technology and a budgetary position are mind-boggling. I typically go through no fewer than 5 designs and multiple products when trying to find the best design for a client. I still have questions on design ideas that I haven’t deployed yet that I’m testing. Since most APs today are multiple radios, the exception being the system we are designing for TriadLand, we are simply going to discuss the 2.4GHz side of the APs.
Because 802.11n is simply faster than b/g, we will stay focused there with the idea of backward compatibility. 1x1 MIMO, 2x2 MIMO, 2x3 MIMO, single-polarity, multi-polarity, and beam-forming are all being deployed. Which one is the best? Actually, most of them have some unique feature. It depends on the application. The right answer is the one that solves the problem within a specific budgetary or financial target. So does that mean there is a universal AP? The short answer is no. The really long answer, which I’m going to need 2 more pages to cover, is still no, but there are ways around most of the issues. Some of the answers, I really don’t know right now because I’m still testing some new ideas. Recent discussions and some new projects have gotten peaked my interest.
Let’s get back to our simplest AP design--our “Tales from the Towers” model. It’s a single omni-directional antenna on a 1x1 single stream 802.11 AP. If all clients are 802.11n compatible, then it can support 30-35 802.11b/g/n clients with a total throughput of about 30-50Mbps, TCP/IP. This assumes good LOS coverage, low-interference, and a low-reflectivity environment. We improved the range by using a very-high gain collinear antenna, which has a higher gain over most of the AP’s that use 6-9dBi antennas. It’s not perfect, but it’s cheap, and sometimes that’s all one needs.
802.11n has a distinct advantage over 802.11b/g, MIMO technology. To take true advantage of it, you need multiple either multiple antennas or multi-polarity dual-feed antennas. The question is, do you use multiple vertical antennas or multiple antennas in different polarities. Do you use 2x2 MIMO, 2x3 MIMO, or 3x3 MIMO? Which one works better with legacy 802.11b/g devices, and does it matter?
To answer that question, you first have to understand antenna polarity. The most commonly used polarities are vertical, horizontal, and circular. We used a vertical polarity omni-directional on our original design, which means vertically polarized in relation to the ground. We did it mainly for budget reasons, but how well it works depends on what the polarity of the client device is.
Let’s examine the typical laptop. Early WiFi-enabled laptops simply had small wires or circuit board antennas embedded on the WiFi card internally. Since the board/wire is typically laid flat in parallel to the table, the antenna would be considered a horizontal polarity antenna. So what happens when a vertical antenna connects to a client with a horizontal polarity antenna? The result is up to a 20dB loss of signal assuming both antennas on both sides are the exact same specification in alternate polarities. In reality, most laptops now have wire antennas that are run up the side of the LCD display and sometimes across the top. That gives it both a vertical and horizontal polarity. This is the exact same antenna design for your AM/FM car radio that is embedded inside the windshield.
Let’s start with the idea of how an antenna creates gain. Antenna gain effectively multiplies the signal being fed into it by borrowing the signal from other directions and refocusing it. For example, a 0dBi antenna is actually theoretical. It’s simply a point in space that radiates an equivalent amount of signal in every direction. Think of the center point of a ball. However, add a driven element and a reflector element, along a horizontal support arm at specific distances and you have a 2-element Yagi antenna that has 6dBi gain in one direction.
We will start with a 0dB antenna. A 0dB gain vertical antenna is really a 2.15dBi gain vertical antenna. That means it transmits 2.15db more power along the ground plane than it does straight up. If we make the antenna longer in multiples of the wavelength, then we get more gain. In reality, the highest non-collinear design I have seen is 12dBi in 2.4GHz. The resulting transmission pattern now gets squashed as less signal radiates upward and more signal gets transmitted along the ground for more range. Antenna theory is still developing with new algorithms coming out not only by engineers and scientists, but also by software programs that are discovering more efficient designs.
So how does 15dBi gain compare to 0dBi? In general, signal doubles in distance for every 6dB of gain. A 3dB signal gain increases the EIRP by a factor of 2. 6dBi gain would increase your EIRP output by 4 times which gives you about twice as much range. 15dBi antenna increases your range roughly by a factor of 6 times.
How does this play out in real life? Keep in mind that there will be obstructions in most areas. That means that getting ¾ of the way through a brick wall isn’t a whole lot more effective than getting ½ of the way through the wall. For walls or obstructions with less attenuation, we discussed how a 15dBi antenna can make penetration through an extra wall a reality due to a 6-8dB increase, or more, over the antennas that most metro APs used. A dual-polarity antenna with a lower gain can produce similar results. I have seen 2.4GHz multi-polarity antennas penetrate better than 900MHz single-polarity radios.
2x2 MIMO provides the option of 2 antennas, both in the same polarity or one horizontal and one vertical. There are even antennas that can do dual polarity or circular polarity in an omni-directional, or directional ,design. There are other variations on MIIMO, such as 2x3, 3x3, or more. If the antennas are directional, polarity is simple and cheap. If the antennas are omni-directional, vertical polarity is still cheap. Horizontally polarized antennas were much more expensive as gain goes up, but recent product releases demonstrate multi-feed dual-polarity antennas have come down significantly. Even dual-polarity parabolic dishes have dropped in price. We will cover these in future articles.
One of the more common horizontally-polarized antennas is the waveguide antenna. In an omni-directional design, they can deliver 13-15dBi, or more, of gain. Directional versions range from 14-18dBi. We used directional wave-guide antennas in some of our installations, and they worked great with 802.11b. One test we did demonstrated a laptop with a Cisco PCMCIA card connecting at 1.2 miles inside a fast-food restaurant.
Another popular design is the circular polarity antenna. The advantage to this antenna is that it transmits in all polarities simultaneously. The disadvantage over a single polarity antenna is that it sacrifices 3dB of gain for that multi-polarity coverage. Most circular polarity antennas are directional, although there are variations such as the Lindenblad design which is omni-directional. All antennas are compromises in terms of gain, direction, design, and cost. That is the reason it’s important to first define the target client before even considering any design idea.
There are a lot of variables to proper design of a system. Although the AP should be the easiest part, not including the antennas, beyond design scope, even firmware of the devices is important. Some APs handle packets differently than others. We discussed CPU overhead and real throughput in earlier articles. Firmware bugs and features also make a huge difference. Now throw in an antenna designs, network management, authentication, security, terrain, building construction, aesthetics, and even unknown challenges that occur after deployment, and this is when having a consultant who simply has more experience, provides value. However, even consultants are another variable, as evidenced by many differences of opinions and designs that have been deployed all over the world. Look for systems that are deployed and functioning and apply those ideas to your needs. Next month we get back to work since Grandma and Grandpa have now discovered Netflix.
Let’s start with the legacy systems that started the whole muni-wireless market. The most basic APs were single radios with a single, or dual, omnidirectional antenna design. These systems covered a fixed area and then simultaneously handled backhaul to the next radio. The first problem with this design was simply the fact bandwidth drops by ½ every hop. Although they also supported diversity for the antennas, that didn’t significantly increase the range. It did reduce fading since 802.11b wasn’t really created with a multipath environment in mind.
Eventually, manufacturers went to 802.11g and started adding 2-3 or more radios with secondary radios for backhaul. Using 5GHz frequencies to hand off the backhaul functions increased user throughput, and with dual 5GHz radios, the multi-hop bandwidth loss problem was effectively eliminated. The multi-radio design also spawned some extremely unique AP designs. Manufacturers started adding directional antennas, multiple frequency coverage, integrated sector antennas, beam-forming, and a few other ideas that don’t pass the smell test for actual performance advantages. However, the reason that there are so many systems out there is that there is an actual need for different features. I have used, and will continue to use, many of these products because of their uniqueness.
Jump forward to post-802.11N MIMO technologies, and the number of options from both technology and a budgetary position are mind-boggling. I typically go through no fewer than 5 designs and multiple products when trying to find the best design for a client. I still have questions on design ideas that I haven’t deployed yet that I’m testing. Since most APs today are multiple radios, the exception being the system we are designing for TriadLand, we are simply going to discuss the 2.4GHz side of the APs.
Because 802.11n is simply faster than b/g, we will stay focused there with the idea of backward compatibility. 1x1 MIMO, 2x2 MIMO, 2x3 MIMO, single-polarity, multi-polarity, and beam-forming are all being deployed. Which one is the best? Actually, most of them have some unique feature. It depends on the application. The right answer is the one that solves the problem within a specific budgetary or financial target. So does that mean there is a universal AP? The short answer is no. The really long answer, which I’m going to need 2 more pages to cover, is still no, but there are ways around most of the issues. Some of the answers, I really don’t know right now because I’m still testing some new ideas. Recent discussions and some new projects have gotten peaked my interest.
Let’s get back to our simplest AP design--our “Tales from the Towers” model. It’s a single omni-directional antenna on a 1x1 single stream 802.11 AP. If all clients are 802.11n compatible, then it can support 30-35 802.11b/g/n clients with a total throughput of about 30-50Mbps, TCP/IP. This assumes good LOS coverage, low-interference, and a low-reflectivity environment. We improved the range by using a very-high gain collinear antenna, which has a higher gain over most of the AP’s that use 6-9dBi antennas. It’s not perfect, but it’s cheap, and sometimes that’s all one needs.
802.11n has a distinct advantage over 802.11b/g, MIMO technology. To take true advantage of it, you need multiple either multiple antennas or multi-polarity dual-feed antennas. The question is, do you use multiple vertical antennas or multiple antennas in different polarities. Do you use 2x2 MIMO, 2x3 MIMO, or 3x3 MIMO? Which one works better with legacy 802.11b/g devices, and does it matter?
To answer that question, you first have to understand antenna polarity. The most commonly used polarities are vertical, horizontal, and circular. We used a vertical polarity omni-directional on our original design, which means vertically polarized in relation to the ground. We did it mainly for budget reasons, but how well it works depends on what the polarity of the client device is.
Let’s examine the typical laptop. Early WiFi-enabled laptops simply had small wires or circuit board antennas embedded on the WiFi card internally. Since the board/wire is typically laid flat in parallel to the table, the antenna would be considered a horizontal polarity antenna. So what happens when a vertical antenna connects to a client with a horizontal polarity antenna? The result is up to a 20dB loss of signal assuming both antennas on both sides are the exact same specification in alternate polarities. In reality, most laptops now have wire antennas that are run up the side of the LCD display and sometimes across the top. That gives it both a vertical and horizontal polarity. This is the exact same antenna design for your AM/FM car radio that is embedded inside the windshield.
Let’s start with the idea of how an antenna creates gain. Antenna gain effectively multiplies the signal being fed into it by borrowing the signal from other directions and refocusing it. For example, a 0dBi antenna is actually theoretical. It’s simply a point in space that radiates an equivalent amount of signal in every direction. Think of the center point of a ball. However, add a driven element and a reflector element, along a horizontal support arm at specific distances and you have a 2-element Yagi antenna that has 6dBi gain in one direction.
We will start with a 0dB antenna. A 0dB gain vertical antenna is really a 2.15dBi gain vertical antenna. That means it transmits 2.15db more power along the ground plane than it does straight up. If we make the antenna longer in multiples of the wavelength, then we get more gain. In reality, the highest non-collinear design I have seen is 12dBi in 2.4GHz. The resulting transmission pattern now gets squashed as less signal radiates upward and more signal gets transmitted along the ground for more range. Antenna theory is still developing with new algorithms coming out not only by engineers and scientists, but also by software programs that are discovering more efficient designs.
So how does 15dBi gain compare to 0dBi? In general, signal doubles in distance for every 6dB of gain. A 3dB signal gain increases the EIRP by a factor of 2. 6dBi gain would increase your EIRP output by 4 times which gives you about twice as much range. 15dBi antenna increases your range roughly by a factor of 6 times.
How does this play out in real life? Keep in mind that there will be obstructions in most areas. That means that getting ¾ of the way through a brick wall isn’t a whole lot more effective than getting ½ of the way through the wall. For walls or obstructions with less attenuation, we discussed how a 15dBi antenna can make penetration through an extra wall a reality due to a 6-8dB increase, or more, over the antennas that most metro APs used. A dual-polarity antenna with a lower gain can produce similar results. I have seen 2.4GHz multi-polarity antennas penetrate better than 900MHz single-polarity radios.
2x2 MIMO provides the option of 2 antennas, both in the same polarity or one horizontal and one vertical. There are even antennas that can do dual polarity or circular polarity in an omni-directional, or directional ,design. There are other variations on MIIMO, such as 2x3, 3x3, or more. If the antennas are directional, polarity is simple and cheap. If the antennas are omni-directional, vertical polarity is still cheap. Horizontally polarized antennas were much more expensive as gain goes up, but recent product releases demonstrate multi-feed dual-polarity antennas have come down significantly. Even dual-polarity parabolic dishes have dropped in price. We will cover these in future articles.
One of the more common horizontally-polarized antennas is the waveguide antenna. In an omni-directional design, they can deliver 13-15dBi, or more, of gain. Directional versions range from 14-18dBi. We used directional wave-guide antennas in some of our installations, and they worked great with 802.11b. One test we did demonstrated a laptop with a Cisco PCMCIA card connecting at 1.2 miles inside a fast-food restaurant.
Another popular design is the circular polarity antenna. The advantage to this antenna is that it transmits in all polarities simultaneously. The disadvantage over a single polarity antenna is that it sacrifices 3dB of gain for that multi-polarity coverage. Most circular polarity antennas are directional, although there are variations such as the Lindenblad design which is omni-directional. All antennas are compromises in terms of gain, direction, design, and cost. That is the reason it’s important to first define the target client before even considering any design idea.
There are a lot of variables to proper design of a system. Although the AP should be the easiest part, not including the antennas, beyond design scope, even firmware of the devices is important. Some APs handle packets differently than others. We discussed CPU overhead and real throughput in earlier articles. Firmware bugs and features also make a huge difference. Now throw in an antenna designs, network management, authentication, security, terrain, building construction, aesthetics, and even unknown challenges that occur after deployment, and this is when having a consultant who simply has more experience, provides value. However, even consultants are another variable, as evidenced by many differences of opinions and designs that have been deployed all over the world. Look for systems that are deployed and functioning and apply those ideas to your needs. Next month we get back to work since Grandma and Grandpa have now discovered Netflix.
Wednesday, June 9, 2010
Chapter 6 – Free is not a Business Plan
Our system is installed and our credit card maxed out. Now, we have to either pay for it or figure out how it’s going to save what we invested in it. As an income based system, it’s pretty easy to figure out a direct correlation between expenses and revenue. If there is some kind of defined savings, we need to try and make that objective and measurable.
Let’s talk about the profit scenario. These are just the direct costs:
-
We spent $10K putting the system in. -
50Mbps costs $450 per month (data center plus roof rights) -
Pole rental costs $5 per month per pole (16 poles) or $80 per month
On the income side, you are going to have daily, weekly, and monthly clients. Let’s say you charge $5 per day, $15 per week, and $30 per month. It’s fairly easy to calculate your income/revenue to put a profitable scenario together. However, let’s go back to the original premise of a low cost system.
A municipal WiFi system has the basic problem of reduced range due to simply physics limitations. I plan to share additional ideas along this area in the near future but for now, let’s assume all clients are 2.4GHz and we still need 802.11G compatibility. This means that we either spend the money on an expensive, all-encompassing infrastructure, ala the sixty AP 2x2 MIMO design, or put that cost on the client side. Having the clients cover part of the Capex not only means a lower initial investment, but costs can scale upward with income.
This design took the original Muni AP concept, added 6dBi or better on the antenna gain, and had the benefit of 802.11N improvements in receiver sensitivity that adds another 10dBm. It doesn’t take advantage of 2x2 MIMO so we left 3-6dBi on the table of signal quality and bandwidth. However, we spent $10K instead of $100,000-$150,000. For 10% or less of the cost, we got 50% of 2x2 MIMO performance and 120% of the performance of legacy 802.11b/g systems. Don’t worry, there is a lot of capacity still left on the table that we can add later.
We now have to deal with the problem of not being able to connect to 60% of the indoor clients. This isn’t unique as most of the Muni-Wireless systems recommended some type of high-power indoor repeater device. Unfortunately, it was an afterthought when they determined that a high percentage of users couldn’t connect or basically that the system was grossly oversold. The indoor repeater balanced the power equation between high-power AP’s and weak laptop transmitter. The problem with these devices is that they create more interference on the channel due to that combination of high-power and omni-directional signal pattern. A better solution for the network is a directional client radio with higher gain antenna and lower power. There are many products but I suggest Ubiquiti Nanostation 2M or Nanostation 2M Loco radios. They have an optional window mount for indoor coverage and cost less than $100. They are also dual-polarity 2x2 MIMO in case the network gets updated later (hint, hint). The radios may need to be mounted outdoor for longer range or to get over the tops of houses or trees which means truck roll. These devices are not repeaters all you get is Cat-5 to the computer. Indoor wireless coverage will require a separate indoor wireless router .
How does this affect our profitability? Assuming 200 potential clients in 1 mile area, we need to get 18 clients at $30 per month to break even on the direct bandwidth costs, not including the payback on our Capex. That’s less than 10% of the potential clients in our 1 mile area, assuming all residential housing. Not an unreasonable number. There won’t be a lot of profit on residential truck rolls but at $200 per install, at least it won’t be a loss.
With 50Mbps per square mile and 70 clients, the system can be cost competitive with most wire line services. What happens however, if there isn’t a data center down the street? We have to figure out how to backhaul from a data center much farther away and probably within a LOS shot for a direct wireless. That could cost anywhere from $500 to $15,000 depending on distance, interference, and frequency availability on the roof. Although you could contact the local loop carrier and ask for a quote on bandwidth, the reality is you will pay $300-$3000 for 1.5Mbps to a 45Mbps DS-3 circuit. Some areas have MPLS and other data options but if you can get 10Mbps for less than $1000 per month from a local carrier, you are doing well.
Another option is to look for wholesale carriers for DSL. Although DSL usually ranges from 512Kbps to 7Mbps average, this goes up or down in an area based on distance to the Central Office or DSL switch. Assuming you can get 7Mbps down and 1Mbps up and your DSL wholesale carriers allows you to resell the bandwidth, you will probably spend about $60. Order 7 of them, put a Peplink 710 router on your network and you have 49Mbps down and 7Mbps up of available bandwidth. No individual gets more than 7Mbps down and 1Mbps up, but the router will load balance the users to get them the best bandwidth available. You are still below your $450 per month budget but the router will cost $4000. Peplink and other companies have smaller routers for fewer DSL lines starting at $300, so you can budget based on expected system needs. Keep in mind your oversell rate of about between 10-1 and 20-1 and that means 70-140 clients getting close to full bandwidth 100% of the time. 70 clients would generate about $2100 per month in revenue compared to your direct costs of $030 per month. The DSL idea can scale starting from 1 circuit keeping monthly costs in line with revenue.
The previous scenario is basically worst case. Assuming you have apartment complexes in the area, not only does the revenue potential increase, so does the percentage of temporary users. These are users that need 1 day, 1 week, etc… The revenue per day for 1 day users is 5 times higher than monthly users. Anything you can do to attract those users is a huge increase in revenue. Throw in areas that include business users, and the revenue potential goes up even further. Business users can be charged 40% more than residential users so there is more potential there also. Hot-Spots like restaurants, parks, etc… will add more revenue.
Here is where we are going to diverge from the original concept of mesh systems and open up the opportunity to make significantly more revenue. It’s been mentioned that the only way to really guarantee 100% performance of a mesh network is to install 60 AP’s per square mile. The reality is that it’s extremely difficult to recoup the kind of capital expenditure at $2500 to $3000 per installed AP (parts, labor, back end, and other miscellaneous costs) you need for this coverage and the monthly costs. Even our design, scaled out to its maximum potential down the road, will cost $1400 per AP installed (but it will it move some serious bandwidth). If it was easy to make a profit, companies would be throwing up municipal systems so fast; it would make your head spin. Throw in monthly costs of pole rental, backhaul or local loop costs, support, business expenses, etc…, and this model fails unless you get the following:
-
The local government pays for use of the network thus supplementing the cost or by being the anchor tenant. -
Sprint, AT&T, Verizon, or some other carrier pays to hand off some of their subscriber bandwidth needs since their purse strings are slightly deeper than most of ours -
You find the 1% area in the country where wired carriers use their monopoly’s to make it easy to compete, there are lots of free vertical assets, and there are very few trees.
The system we designed achieves the strategy of 100% street coverage which meets most of the needs of public safety and municipalities. This opens up the government market. We have determined that some users will need indoor subscriber units. However, the one area that hasn’t been covered directly is the idea of the system simultaneously being used as a Point-To-Multipoint (PTMP) system. Basically we need a hybrid muni system. A PTMP system has the advantage of range but doesn’t provide street level coverage and usually won’t cover indoor. With an outdoor antenna on the client side, the system can support clients up to 2 miles away LOS. Our upgraded system will support up to 5 miles or more. This greatly multiplies the potential revenue of the system. Clients purchasing indoor units are creating a mini-PTMP system already. The only difference is that as the provider, you will have to provide staff that can go on-site and install a radio in a residential location. On the positive side, it can also be another source of revenue since the cost of equipment will be less than $110 for the install. Keep in mind that every subscriber we add brings in another $360 per year or more. This design with that addition, keeps the best of both worlds.
The focus of municipal networks has historically been high-density areas. The obvious advantage is having a market potential of 10,000 clients or more. These are the kind of numbers that are needed to cover a multimillion Capex. The budget model we created allows for much lower density deployment while still creating a design that creates a product that has value for public safety, water meter, parking, video surveillance, and other options that create value for a municipality to become a client. That provides two potential markets. Throw in the PTMP market, and we have not only created 3 markets, we can provide a more reliable, stable product with higher bandwidth capacity per client, and a larger coverage area.
Does this change the model of a true municipal network? Not really. Besides cellular, the most profitable wireless networks are PTMP. They cover many of the areas that wired never moved into. For example, I have an area of 50 homes that was never profitable for wired due to the length of runs. Put up a single AP with an omni-directional antenna, feed it with a T-1, charge $60 per month, and everybody wins. It beats satellite hands down and people still watch Netflix. Some part of the municipal network usually has roof rights for backhaul, usually on unlicensed frequency, to the AP’s on streetlights if they aren’t attached to fiber. Those locations are providing a PTMP system already for the AP’s. I’m suggesting that this same model be used for clients. In later articles, I will show you how this part of the network can be upgraded to easily deliver 20Mbps to residential and 50Mbps or more to businesses.
I’ve taken some heat for the fact that this system isn’t 2x2 MIMO. Keep in mind that this was first designed to create an inexpensive and/or profitable network. It will perform better than an 802.11b/g system due to better receivers, higher antenna gain, and better protocol. It can also support a PTMP design that can cover a couple extra miles around the 1 mile area for additional customers. The network is better controlled with more users using directional antennas for indoor coverage which reduces interference in improves s/n ratio. It doesn’t have 100% indoor ubiquitous coverage but it also doesn’t cost $150,000 per square mile, although it can be upgraded. We will next cover how to increase the bandwidth at each AP up to 80Mbps or so and expand the total capacity.
Sunday, May 9, 2010
Chapter 5 - Reality, what a Concept
In the last article, AP’s got hung, WDS links were set up for hopping, and we were ready to attach to Internet. Although TriadLand is ready to rock, we now need to connect the users. First we need to attach connect the network to some type of Internet service and then come up with a way to authenticate the users that want to use it. After that we will cover the details on some of the system management and how to overcome them.
WISP operators are typically forced to work with local bandwidth providers who typically have some type of monopoly for the area. A WISP can’t resell most of the business services over DSL or Cable due to the local provider not allowing that. WISPs are generally resigned to T-1 circuits or more expensive business options. Assuming that you order a T-1 for your system, you now have 1.5Mbps of bandwidth for your network. If you plan on using cable or DSL services, check with your local provider to see if that is allowed. Other bandwidth options are also available but you will have to check for each area.
Assume that one of the 4 center APs out of 16 are the Internet connection point. We will set up the WDS links so that now end point is no more than 4 hops (meaning we may have to skip one) which will keep the last AP with around 5Mbps at the end point. If we can skip more than one AP, we can keep the hops to 3 or even 2 if we have LOS between the AP’s. We have enough signal to hold very high modulation rates with ½ mile links between APs. Keep in mind that APs between the end point and the egress point will be handling users while simultaneously passing WDS backhaul for other APs down the chain. This will directly affect throughput for users down the chain. It is one of the limits of this design but no different than any of the other earlier mesh designs. The end result is that the entire square mile will eventually be routed through one AP.
One key issue I received a couple of emails on involved security. The drawback of inexpensive radios is that you may have to give up something in return for the reduced price point. This system provides no encryption over the WDS links. This problem gets resolved with additional hardware as part of an upgraded system. The system can run security between the laptop and the AP but there isn’t much use if the AP hops aren’t secure. If you plan on upgrading later with more bandwidth, then it might be a good idea to get the users to use WPA2 on the APs from day one so they won’t be confused later. Just make sure your EULA clearly states that the system is not secured over the wireless link.
The second problem with this network is that it only supports a single SSID. I do not know if that is going to change in the future. There is third party firmware that will run on the Bullets that may offer more options but that typically comes with additional costs which gets away from the original premise. If you need security, then VPN tunnels are the only option with the basic system. Phase 2 resolves most of the security issues.
There are many good products out on the market for authentication of users. Our sites use Patronsoft Firstspot for user authentication and management. FirstSpot runs on Microsoft Windows XP or Windows Server, can support SQL Server for extending site deployment and centralized user management, uses PHP for the web pages, and can run fail-over servers for offline management. Since our company has years of experience with Windows, it works for us. Those of you with more experience with Linux have many other options. We ran tens of thousands of users through our servers over 5 years so I’m pretty comfortable with it. However, it’s not CALEA compliant yet but they are looking at it now.
Triadland is up and running. Users attach to the broadcast SSID, get a login page, diligently read the EULA word for word in which they agree to follow the rules, and then they get online. Now what happens? This is stuff normally planned out in advance but the article focus was determining the basic wireless technology first. It’s time to deal with the actual functionality of operating the system.
This is where every WISP’s worst nightmares start. It begins with the Federal government getting access to your system in the name of Homeland Security and ends with junior making it his personal mission in life to download the entire Sony movie collection. Your first job is to file your CALEA paperwork. CALEA is an entire article by itself and I may cover it much later. Go to http://www.wispa.org/?page_id=2022 for more information. After that, you need to figure out how you are going to keep control of junior. You are also going to have to deal with the users that move large amounts of spamware or spyware without even knowing it. These same users can get you disconnected from your Internet circuit if it’s bad enough.
Let’s move on to the first issue which is keeping control of your network. Several things will stress both you and your network. Let’s start with junior’s desire to fill up that new 2 Terabyte hard drive he just got for his birthday. File-sharing is one of the biggest problems faced by most ISP’s. Fortunately or unfortunately, depending on which side of the equation you are on, recent rulings by the FCC allow operators to limit file-sharing. There are 2 basic ways to handle this. You can use either an authentication server that keeps track of bandwidth used or a web application firewall that allows you to block file-sharing applications. Limiting users to 10GB – 20GB per month is a good start.
Early on, we had an incident where some users on our network had been infected and turned into spam servers. The bandwidth provider started blocking Internet for the entire system until we got it resolved. With 200 plus users and some of them still running Windows 98, the battle to keep viruses and spam under control is difficult at best. We purchased a Barracuda Web Application server which not only blocked the offending users, it redirects them to run spam removal software and won’t let them on Internet until the computer is cleaned. A Web Application filter also allows blocking of specific websites that might cause unwanted legal attention and file-sharing applications.
Now that we have built our 1 square mile network in Triadland, our next step is to make either make it profitable or find a way to give it purpose. We will cover those ideas next article.
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