Chapter 19 – Catch a Wave-Guide and You are Sitting on Top of the World

The Beach Boys are going to hate me for this but I’ve been waiting for years to use that line. I also wanted to title it, “Look Ma, no mesh” but I should have used that one several articles ago. It’s not that I have anything against mesh as there is an application for almost every technology. At this point in the industry and the economy, however, it’s time to get past a word very few non-technical people understand and the excessive associated cost of it. Anyway, this article is about wave-guide antennas so let’s get back to that.

Vivato was a wave-guide based antenna. I have had Securawave wave-guide antennas installed for about 7 years. I became a believer when I connected a car at 2 miles and my laptop inside a Jack-in-the-Box at 1 mile. The horizontal polarity was a huge advantage since most wireless APs were vertical polarity. Securawave is no longer in business so I’m hoarding the last few units I have to support units I have in the field. Not that solid aluminum blocks have a tendency to fail as I suspect they will last longer than the buildings they are mounted to (they just don’t make them like this anymore), but in case of physical damage. I don’t need dual-polarity and 2x2 MIMO yet in these areas because Qwest hasn’t figured out how to get more then 3Mbps over the so-called HD Internet services and I’m not ready to mortgage my house for their other service offerings. Of course it’s hard to dial the phone when your eyes are tearing up from laughter when they advertise their new 40Mbps service. 18 months ago they couldn’t even keep a 640Kbps DSL line running properly in the middle of Phoenix less than 1 mile from Sky Harbor Airport.

Historically, wave guide antennas were expensive to make which is probably why it didn’t have more popularity. Ubiquiti seems to be bringing it back with its new omni-directional dual-polarity antennas. We know that dual-polarity has better penetrating and range capability than single polarity. So the idea of extending that into an omni-directional antenna seems like a great idea. Since there isn’t any other 2x2 MIMO omni-directional dual-polarity antennas that I know about, this is really cool from a technical, design, and financial standpoint. It’s also how we are going to keep Guerilla WiFi cost-effective and make it better.

The new Ubiquiti omni-directional antenna isn’t a true wave-guide antenna. Since it needs both polarities, half the antenna is basically two 180 degree vertical polarity sector antennas back to back with dual 180 degree wave guide antennas. Since it’s not out yet, I haven’t tested the unit but the pre-spec guess is it’s around 12-13dbi. That means the effective LOS range with dual polarity is going to be about 30% farther than an omni with 15dBi of gain for a couple of reasons. However, real world performance is going to be significantly better since dual-polarity will definitely penetrate vegetation better, reduce noise off-polarity, and reduce fading. If the client is using a dual-polarity indoor radio, then not only will range be better, noise will be significantly reduced even further. I smell a huge performance improvement in the air for Guerilla WiFi.

Let’s go back to Chapter 1 of Tales where we designed a $10K per square mile system. In that design, we used a 15dBi omni-directional antenna with a single polarity omni-directional. This design was using a single stream 802.11 b/g/n design. With the new dual-polarity omni-directional antenna, we still use a single radio for our AP but we have doubled the throughput with a 2x2 MIMO stream. In addition, we have doubled the throughput of every hop and added an additional hop. Even at the 4rd hop we are still delivering up to 10Mbps. Keep in mind that at a 10-1 oversell rate, that means that you can sell twenty clients 5Mbps at the end of the chain. Although pricing hasn’t been released, I’m pretty sure this antenna with a Rocket M2 radio will still cost less than $300. Double the performance of the original Guerilla WiFi at no additional cost and it’s better than triple coupon day at my local grocery.

Think about that for a moment. If we only had one egress point for our network, our base network was limited to 3 hops with the same capacity at the end. This single antenna, which allows us to change from a single stream 802.11b/g/n radio to a 2x2 AP, doubles that throughput, thus extending our single AP model out even further and doubling bandwidth down the chain. Our egress point can also use multiple radios which can triple the throughput to 3 times that for $300-$600 more without even getting into out next topic, GPS Synchronization. So for less than $11K per square mile, the system now supports 180-300Mbps, depending on the clients. So if your town is 20 square mile and this whole system cost $250K to put in, then it’s a no-brainer simply for cameras, security, mobile access, and department efficiency. Of course, if it goes through federal funding, has government engineers add in the fact that it has to support mesh (pointless in this and most designs but adds significant costs), throws in ridiculous temperature requirements like -30C for Phoenix or 80 degrees centigrade when -75 degrees centigrade would work fine, and requires copious amounts of paperwork to tell 14 different government agencies that you are paying wages equal to union scale even though you pay your guys more than that, then it’s going to cost $1,000,000 (my English teachers just had heart attacks over that sentence). If you can sense my frustration with federal rules that require union contractor shops to do work that is clearly better suited to IT companies, then you are very astute. This is why projects involving the government cost so much and take so long.

If this is a for profit network, $250,000 to cover 20 square miles with this level of bandwidth is pretty impressive. It’s fairly easy and cheap to add 100Mbps backhaul to each square mile for a total of 2GBps for the entire system. Realistically, I would guess that you would get about 500Mbps before the price starts going up for full-duplex links. Keep in mind that we are back to the core idea of an inexpensive municipal deployment.

Using numbers from previous articles, let’s assume 800 potential clients per square mile. If we get 10% of that base at $30 per month, that’s $48,000 per month. With this type of system, only a very small percentage of clients are going to need truck rolls. Total revenue on this network is almost $600K per year. If users have to get client radios, then they start at $30 for 802.11n 1x1 Vertical Polarity CPE’s. For about $80, you can include a window mount and get 2x2 MIMO. In most environments, I would be surprised if truck rolls needed to be done on more than 10% of the clients. Even if you add in the cost of the client radios, this system should be cash flow positive at 800 clients and should pay for itself at 2400 clients within 12 months. This just covers residential and doesn’t even get into business revenue. The numbers are now speaking to me so it’s time to kick the venture capital market back into high gear.

Also consider this, the 16 AP per square mile strategy now covers a higher percentage of deployments, especially profit oriented ones. If you live in the middle of high-density city, then you would want more APs per square mile for density or you fall back on the super AP concept described in previous articles. Since WiFi is far more unpredictable that PTP RF modeling, there is nothing wrong with installing 16 AP’s and then site surveying to see if there are coverage gaps than hinder more revenue.

Cell phone companies don’t cover every square inch of every house on the planet. It’s not cost effective. They deploy with the best models they have and then decide if it’s profitable after field testing to fix poor signal areas. WiFi should be deployed the same way. Put up 16 AP’s, field test, check the areas with poor coverage, and then decide if it’s worth another $300 in equipment to cover that area. If an area has higher usage, add in a triple radio AP upgrade for a few hundred dollars more. If an area really just needs more signal gain, look at adding a beam-forming AP just for a specific direction. There are many options but all of them would be based on sound profitability principals. There is nothing wrong with walking away from 2 customers that might cost $3000 to add additional infrastructure to cover.

I have 2 “Peeves of week” I have to get off my chest. The second is 99.999% uptime. I was asked to design a system where I have to guarantee the CPE’s have 99.999% uptime. Since the wireless industry has new equipment out every few months, very little of what I would deploy today has enough history for me to put my reputation behind that request. I’m not talking about PTP full-duplex $10K and put links but $50-$400 CPE’s. First off, anything less than 802.11N is too old and too slow for this type of video application. Second, anything that’s 802.11N hasn’t been around long enough to know how it’s going to run 3 years from now. It’s kind of a catch-22 situation. That means using cameras with built-in recorders that are going to cost three times as much or more than using lower priced cameras with CPE’s. Unfortunately there is no product history out there than guarantees that. The reality is that all the radios I work with rarely, if ever, just simply go offline if installed correctly. That doesn’t mean that they aren’t going to down for planned firmware upgrades or other system changes. However, the 99.999% uptime request didn’t stipulate whether planned maintenance was included.

I’ve already mentioned my first pet peeve, municipal bids that ask for mesh when every AP connected has a directional antenna. To everyone who keeps adding this expensive request into these bids, it’s a waste of money taxpayers’ money and costs the city a lot more to support in the long run. When you add a directional antenna to an AP or CPE, it’s a PTP or PTMP design, regardless of what firmware is on there. There is no mesh because the radio can’t connect to anything it’s not pointed at. By adding the mesh requirement, you are either getting the most expensive product out there or White Box APs with custom open-source mesh firmware that is cheaper. I’m not saying there isn’t a place for mesh, but don’t eliminate other options like WDS. It’s not your money you are spending; it’s ours, the taxpayers. Let the industry and a wireless engineer decide what the best product for the design is. It shouldn’t be the salesperson that took you out to lunch last week and has shiny brochures. If mesh is appropriate and the best fit, let the companies bidding on the project put that down. If WDS will work just as well or a PTMP design is better, they will bid that. So can anyone guessed what crossed my desk again this week? I know I’m beating my head against the wall on this since arguing with government is like trying to tell a 3 year old that candy isn’t good for them.

So we have come full circle on Guerilla WiFi from $10K per square mile to $50K per square mile and now back to $10K per square mile with double the performance. If this doesn’t kick the industry back into high gear, I’m not sure what will. Next we will cover GPS sync and how that affects deployments strategies.

Chapter 18 - Demystifying Beam-Forming

Based on some of the emails I’m getting, the biggest complaint is not enough details and without them, it’s difficult to implement the idea. Fair enough, I’m definitely guilty of that. In my defense, please understand that I want to have a personal life. Not that I have one now, as most WISP’s can attest, but if I had to put down every single detail on every single project or idea, I would be writing from here to Kingdom come. Except for the 6 guys on the planet like me that think they ought to make a movie out of every article in EETimes (I think a lower noise figure on a 741 OP-Amp makes a compelling plot line), most of you would be cancelling your Ambien prescriptions. The reality is that the details only matter to technical people and those are called White Papers. I’ve written a couple but I can’t sit still long enough to finish dinner, let alone do a 20 page technical document. My wife says that if I had put as much time into my homework as I have these articles, I would have my Master Degree by now. Of course, if University of Phoenix gave me real life credit for standing in a man-lift hanging antennas 80 feet in the air, I could get my Doctorate without ever attending class.

Let’s get back to the really cool stuff like beam-forming. We covered 900MHz and both the positive and negative aspects. Let’s move on to the category of what’s old is now new again, beam-forming. Vivato pioneered the idea several years ago but the financial model, coupled with irresponsible pre-marketing, didn’t really work in the real world. However, they did get the FCC to change the rules which is going to be a very good thing moving forward. The difference is how the different implementations of beam-forming are implemented and the effect in the real world, technically and financially.

Long before Vivato, the Super Scanner antenna from Antenna specialist tried to get an antenna to function in both a directional and omni-directional mode with the turn of a knob. Some of the manufacturers such as Wavion and Netronics sort of copied this model by using a ring of vertical omni-directional antennas. They can get up to 12dBi of antenna gain off of 7-9dBi antennas. Currently these units are limited to 802.11b/g bands and vertical polarity.

The next kind of design was done by SkyPilot where they simply rotated connection to one of 8 integrated sector antennas at any one time. This gave them up to 44dBm of EIRP in the 4.9-6.0 GHz bands. Ruckus, Netgear (with Ruckus helping), Cisco, and others are now integrating the antennas on circuit boards but at a lower gain. There will be several antennas cut into the boards or some other internal antenna hardware to add vertical and/or dual-polarity to the board that provide directional coverage. These designs are achieving up to 10dBi in gain with the bigger advantage being the noise reduction from other directions. They use the model of picking the 2 best signal antennas to receive the signal simultaneously since doubling antenna capture area provides up to a 3dB increase.

Vivato is still the technical King here in this realm though, although they weren’t covering 360 degrees. Vivato achieved 24dBi of gain in a 100 degree pattern in 2.4GHz. The catch is they did it for $8,000-$15,000, which meant I could either buy a new van for my company or 2 APs. That sort of limited the market for the product to the point that they are no longer in business, which is also what happens when you don’t listen to your vendors trying to sell the equipment. However, that 24dBi of gain is a huge advantage for reaching underpowered smartphones. Since Ubiquiti has now announced that they are releasing a beam-forming product over the next 2-4 months, the question is, does that have value for a municipal design?

Getting back to today, Wavion’s newest product, the WBS-2400 is probably the closest to the Ubiquiti beam-forming radio. It’s also very similar to Altai A8-Ei product with multiple radios, sectored antennas, and one enclosure. Both products tighten up the beam and assign a single radio per antenna. Unfortunately, both these products are still b/g.

Going back to the formula that distance doubles for every 6dBi of gain, if a 2.4GHz beam-forming AP has 21dBi of gain, or what I’m guessing the new Ubiquiti units are going to be, that almost quadruples the range of most omni-directional AP’s. Throw in the fact that noise will be reduced by at least -20dB, and the s/n ratio goes berserk. The effective range increase, and this is only my best estimate in the worst scenarios, is probably a factor of 8-16 in open air environments. This means hitting a smartphone at 3000-4000 feet or more is possible.

Here is where it gets interesting though. Based on past experience, I’m guessing the Ubiquiti beam-forming AP will be less than $300. That is 10 times less than other beam-forming products, none of which support 802.11N 2x2 MIMO. Heck, it’s less than I paid for a baseball bat last season.

We were all trained to think in terms of APs needing to cover 360 degrees for municipal deployments. Every product out there is designed for that. The end result of this is when the density reaches a certain level, the self-interference is basically self-defeating. I’ve seen proposals that suggest 60 APs per square mile for example. Central management systems can dynamically adjust power output between APs to reduce the interference and can simultaneously adjust power output on a per packet basis to reduce the interference even further. However, all this costs which effectively drives the price up to $150,000 per square mile or more for this level of performance. However, what in the playbook says that every AP has to have omni-directional coverage?

Throughout this series, we’ve been driving towards a low-cost, high-capacity design that can be commercially deployed. The original idea was trying to develop an inexpensive Super AP. I’ve gone from $200 to $2000 and was working on an idea that would have driven the cost to a retail level of $4000. It supported 1Gbps per AP and 700+ simultaneous clients, but still it got away from my original idea which was to lower the bar on the per mile cost, which it didn’t accomplish. It basically comes down to the following, are you trying to compete with cable which can deliver up to 50Mbps or delivering Internet to people who have to suffer with dial-up, or worse, DSL delivered by Qwest in Arizona (okay, bad joke).

Beam-forming lets us start with a new playbook. The first thing you do in a playbook is define your assets (okay, I never played organized football so I’m making this part up.). Using the Ubiquiti beam-forming product (2.4GHz version), we know roughly that we will have about 21dBi of gain, 90 degree coverage zone, 16 degree beam pattern, GPS synchronization, and 2x2 dual-polarity 802.11N MIMO. Since we can now hit a phone at 2500 feet without much of a problem in open air, the design mentality changes. Even with 21dBm of gain, we still aren’t going to penetrate several buildings. However, we probably bought ourselves another house or two. By changing the angle of transmission, ala cell towers, and to be fair to Vivato’s deployment design in Spokane, tops of buildings aiming down, and all of a sudden we are hitting several houses down the street. Throw in 2x2 MIMO dual-polarity, and the connection distance goes way up.

Because of the price point, I’m guessing Ubiquiti’s product uses the same type of design as SkyPilot in terms of switching between multiple feed points on the antenna. The difference is that each feed generates a different angle of radiation versus being a completely separate physical antenna. Ruckus hits multiple feeds also with circuit board based antennas.

Although the tops of buildings aren’t ideal for sector antennas due to amount of AP’s that are going to get picked up, if you aim it towards the horizon, angle it down 60 degrees or more, you still get coverage down the street and pretty impressive building coverage. At that angle, you are reducing attenuation from outer wall penetration and even taking the route of shooting through the roof. This doesn’t work all that well in areas with trees, but if the buildings are made out of concrete, brick, or stucco, then this might be the best option. There are a lot of cities where the street lights are decorative and there is no way to install an AP down at ground level, so secondary options are a must. Beam-forming makes this design more useable by effectively reducing the beam pattern down way down.

This model might work in a different way also. Think in terms of 3 dimensions instead of 2. Larger buildings or apartments in downtown areas might be 10 floors or more. Placing these antennas on the side of one building several stories up and aiming into another building let’s you build a vertical WiFi Although attenuation has been a killer, 21dB of gain makes up for a lot of wall and window attenuation. In addition, dual polarity will improve penetration even further. If you pick up 30 customers in a building at $20 per month, 3-4 antennas pointing into the building get paid for in a couple of months. I would have also said it’s significantly cheaper than AP’s in the building until I saw another product that I’m testing (to be discussed later). However, when you add in the savings on pulling cable, it’s a no-brainer.

Irregular areas with streets curving all over the place are another option for this type of design. Intermixed homes and small business areas with mostly 1-2 story homes and 2-5 story buildings work well for this design. Outdoor coverage is universal with indoor coverage hitting around 80% or more with careful planning. Keep in mind I’m assuming everyone wants to give you free vertical assets to enhance the system.

Bringing us back to earth gives us most of the real-world deployments, street lights. This is where the GPS synchronization really kicks in and is now the direct comparison to Wavion or Ruckus. Placement of four of these radios on a pole to cover 360 degrees provides the absolute farthest range of any AP on the market. This is only possible with GPS synchronization to keep them from interfering with each other. It effectively provides twenty four 16 degree beams shooting out in 360 degree pattern. The cost of this super AP will be about $1500 which isn’t a lot less than Wavion or other beam-forming 360 degree APs. It does have significantly longer range through, by a factor of 9dBi and dual-polarity which is worth another 3dB in my field testing. With the IPad supporting 802.11n and the Beam-Forming antenna supporting dual-polarity, this would be a potent combination for off-loading some bandwidth.

If we duplicate this design with Altai or Ruckus, the cost is now over $10K per AP. There are other manufacturers such as Motorola that use sector antennas but then the antenna gain drops back to 12dBi or less and their beam patterns are 120 degrees. The best way to reduce noise is to decrease the beam pattern which it also doesn’t do. Effectively we get a 9dBi increase and 20+dB of noise reduction for a cumulative 29dBm improvement in s/n ratio. Regardless of what wireless philosophy you follow, that’s huge.

Here is one of my philosophies though, “If you spend too much, all you have lost is a little money. If you spend too little, you could lose everything.” Guerilla WiFi is based on the concept of being the most cost-effective way to deploy and what I feel is the only way to make municipal wireless a self-sustaining profitable model. That doesn’t mean it’s the best way in every situation. I’m describing equipment that isn’t even out on the market yet and isn’t field tested. Wavion, Ruckus, Altai, Bel-Air, Motorola, FireTide, Cisco, Enterasys, and a host of other vendors are proven products that have been deployed and tested. I do think these vendors are making it difficult to meet the financial needs of a profitable municipality model which is where Guerilla WiFi comes in, but the products are solid. This models works for me and others who are willing to spend the time to work through early firmware issues and fine-tune the models during deployment. It’s kind of like the difference between Linux and Windows. Since Ubiquiti uses a common firmware platform across all of their outdoor products and has made great strides towards stability and features, I expect the new products to use the same firmware base which means , the firmware. However, there is still a long way to go towards a turn-key municipal deployment without a lot of engineering intervention. Based on the cost/performance ratio, I believe it’s worth it. But realistically I spend a lot of time testing and adjusting. Most customers are going to expect a more turn-key solution. However, if it’s your money, then this solution provides the best chance of financial success.

With this AP design, $1500 per AP is getting pretty pricey. However, it will also combine with our next article, the 360 degree dual-polarity 2x2 MIMO AP for under what I’m guessing is going to be $300. I’ll try not to wait 3 weeks to make this happen.

One other note that I want to mention is that Mike Ford is no longer at Ubiquiti. Mike was a central figure that seemed to have his hands in everything from testing to customer support. Over the last 3 years, he has become a friend that always went the extra mile to make sure I had the resources I needed for my clients. He was also instrumental in some of my decisions on my deployments. Although I don’t know his future plans, I am very sorry to see him go.