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LTE-U in 5Ghz: An Introduction

Ericsson RBS 6402 Indoor Picocell

Ericsson RBS 6402 Indoor Picocell

Estimated reading time: 3 minutes, 46 seconds. Contains 756 words

I’m trying to wrap my brain around LAA-LTE. I understand what it’s trying to do, but not why. I mean that makes sense to me. Users are already choosing Wi-Fi over LTE when it's available. LAA will be used for downlink data only and most study's show that Wi-Fi use is significantly greater than mobile data usage anyways. Also, the carriers OWN their own spectrum, and unlike 5GHz, they control it, and have the ability to manage it. 

So, why encroach on unlicensed spectrum? They'll have to abide by the power constraints in 5GHz, so in-building, small-cell deployments seem to be the way to go. Does this mean lots of indoor carrier pico-cells right next to existing APs? 

I wanted to learn a bit more about LAA and this is what I found so far...

What is LAA? It stands for “Licensed Assisted Access”. Basically, the carriers want to use 5GHz to supplement their “primary” LTE cells with a secondary cell in unlicensed 5GHz. This cell (in the initial stages of LAA-LTE at least) will be for downlink data transmission only. The “License Assisted” part means that the 5GHz cell is linked to the “Licensed” cell via “Carrier Aggregation” (think channel-bonding.. sort of). But, all control functions reside in the licensed spectrum cell and can even disable the 5GHz secondary channel if necessary. At issue here is not the use of 5GHz, which is unlicensed and so by definition anyone can use, but HOW it will be used.

In countries other than United States, China and South Korea, there is a regulatory requirement to “Listen-Before-talk”, or LBT. Since we have no requirement for that in the U.S. carrier manufactures are looking for other ways to place nice with Wi-Fi. The “how” is still up for debate. But, one thing seems clear, they won’t be using CSMA/CA. Qualcomm has a white-paper about this specific issue. Nokia has one to, but you have to buy it. No thanks, I'll just stick with Qualcomm's. Some of their proposed “Coexistence Mechanisms” are:

Channel Selection - attempts to pick the cleanest channel based on Wi-Fi and LTE measurements. Basically, it uses energy detection to see if how used the channel is.

Pretty straight forward, it scans the medium to find the channel that has the least usage. So, in small, to moderately-sized WLAN it should’t be a problem. Especially with DFS enabled.

Carrier-Sensing Adaptive Transmission (CSAT) - "...the cell senses the medium for a duration (around 10s of msec to 200msec) and according to the observed medium activities, the algorithm gates off LTE transmission proportionally."

This one is interesting. If the medium is found to be pretty saturated, and a “clean” channel is not available the cell will fall back to CSAT. LAA-LTE uses an “on-off” duty-cycle pattern. When the medium is heavily used, CSAT will change the duty-cycle timing it will use. It will still use the 5GHz spectrum, but settle on the "least harmful" time-cycle. It also uses only primary channels to mitigate inference with QoS traffic. However, this duty-cycle is directly proportional to the throughput of wi-fi client. In other words, throughout is reduced.

CableLabs.com has a nice piece on this and actually shows the correlation of the LAA-LTE duty-cycle  on wireless clients. 

Opportunistic SDL - “Since the anchor carrier in license band is always available, the SDL carrier in unlicensed band can be used on an opportunistic base.”

The Supplemental Downlink (SDL) can be enabled, or disabled, on-demand as necessary. In theory, if the primary LTE cell in the licensed spectrum can handle the traffic, the 5GHz secondary cell is turned off. Then if unlicensed offload is required the secondary cell can be turned on. So, LAA-LTE may not always be present. If the carrier's primary channel can handle the load 5GHz won't be used. Question is, will the carriers actually do that?

Qualcomm's white paper claims "due to the coexistence safeguards. In fact, the Wi-Fi performance improves by about 10%, since the neighboring LTE-U Picos can finish transmission faster and incur less interference instead". I don't know about that, and 10% over what?

I'm skeptical about the affect LAA will have on WLANs, but I'm willing to learn and be proven wrong. Also, this is just one more thing we as WLAN professionals have to account for in our wireless designs. 802.11 is already a pretty inefficient protocol and adding more overhead to 5GHz doesn't seem like it will improve anything except the carriers sense of well-being.

Qualcomm White paper:
LTE in Unlicensed Spectrum: Harmonious Coexistence with Wi-Fi

CableLab.com article: 
Wi-Fi vs. Duty Cycled LTE: A Balancing Act

Bad Design at Your Request

Estimated reading time: 6 minutes, 44 seconds. Contains 1348 words


What does one do when presented with a highly questionable request from a customer? Nothing immoral here, just when a potential customer is asking you to do something you know won’t work. I had this exact scenario happen this Summer with a resort that wanted to do a wi-fi refresh.

Originally, the customer just wanted to do a rip-n-replace - swap out their existing 7-year old, 2.4GHz APs - with new APs. After some discussion we convinced them that a simple swap out was not the best solution. We agreed to do a predictive design using data collected from Our site visit.

One of the caveats was that the APs could not be in the rooms. For aesthetic reasons, and others, management wanted no APs in rooms. We knew this would not be an ideal solution, and we let this be known on several occasions. After explaining our reasoning, IT was in agreement with us on this matter. However, the management was not convinced and decided to take a chance on the hallway “design”.

We did our best in collecting data on-site and used that data in our predictive model. In the end the initial deployment was a hallway placement. We adjusted some AP locations and added some, but I knew this solution would not yield the desired results. Directional antennas brought the budget to more than they wanted, so those were not an option. They also wanted this in on a tight time-line. I had made my concerns know at multiple occasions, but there was no budging from management.

So, I could choose not to do this project and walk away, or sell a solution in which I was not confidant. Well, I have a business to run, bills to pay, and employees to… employ. I chose to “design” a solution within the constraints - both AP placement and budgetary. With this in mind I drafted the cover letter below for the design I presented to the customer:

Thank for this opportunity to allow us to present you with a wireless access solution for your wonderful property. Before you proceed to the information in the document please indulge us and read this overview in its entirety. It will clarify the purpose and scope of this document.

This report is a “Predictive Survey”. The term “predictive” is used deliberately to denote the fact that the process used in the creation of this report is a best guess and will most likely not be 100% accurate. In a structurally complicated deployment such as yours we can probably assume a 75-80% accuracy rate.

Predictive surveys are a very useful tool for the Wireless LAN Professional when a full, cost-prohibitive survey is unavailable. There are two methods to perform a predictive survey:

OPTION 1. Using only the floor plans and a questionnaire we can use the survey software to automatically place the APs and then manually adjust to our specifications. We can alternatively manual add the APs to specification. This type of survey is best for traditional, modern open-floor plan office environment where the loss and performance characteristics are well known. This is also the most cost-affective (up font) solution and very commonly used. In the end you get the best data out when you put the best data in so this option should be used sparingly and mainly for budgetary purposes.

OPTION 2. Perform a physical site survey to become aware of the building materials in use, current AP locations and limitations, physical build of the rooms and furniture materials and locations, etc. Also, using the same APs and antennas that are being proposed take as many readings as possible to determine the true signal loss at varying distances from the AP. We also are able to look at various types of RF interference that may be present, and possibly mitigate that interference before the deployment begins. This allows us to use that data to better build our predictive model. This is less cost effective than option 1, but more cost-effective than a full site survey, and allows the model to go in with the best possible data that the circumstances allow.

Option 2 is what we have done. We spent time on site taking readings, and noting material types as we could. Obviously, in an environment as busy as yours it was not possible to have access to every location so we did the best we could taking readings in multiple rooms and room types and through the various material types at your location. This is not perfect, nor definitive, but it will at least give us valuable information to use when making our predictive model.

We would also like to take this moment to also state that locating all the APs in the hallways is the least effective model in a multi-room, multi-tenant environment such as yours. The best-case scenario here is allowing the APs to be located with-in the rooms. This allows us to use the structure of the building itself to allow for separation between the APs and help mitigate interference as well as getting the RF signal closer to the clients. We understand that this is not always possible for a variety of reasons, but we felt the need to make you - the customer - aware of the limitations to which this design has been restricted.

In conclusion, we ask that you look at the following report with the information in this overview in mind and with the understanding that after deployment we highly recommend that we (or a 3rd party) perform a validation survey to confirm where the predictive model falls short. Upon the results of this verification there may be several things that need to be done. It may be adding, relocating, or even removing some APs, or we may simply need to disable certain AP radios to reduce co-channel interference. Either way the design is not complete in our view if it has not been validated after implementation.

With this in mind please proceed to review the report. Thank you.

Eddie Forero, Principal CommunicaONE Inc.

The report essentially showed what we had been saying - that APs in the hallways would not provide the in-room coverage they desired. We also provided an alternative design with APs in room. In the end the management went ahead with the hallway solution despite ITs misgivings.

The end result was not much better than what they had. I fully expected to bear the wrath of the customer. I was not happy that I installed a solution I didn’t believe in. And I was not expecting what happened next.

The Director of IT flew out the the head office to present the results of our post-installation validation survey. He showed that hallway APs were providing great “coverage” in the hallways, but not in the guest rooms. He explained how we had predicted that this design would not give them the results they were after and the gamble did not pay off.

Because we had been very clear about our concerns, and because we had clearly stated, then validated those concerns, the management decided to foot the bill for a complete in-room redesign (using different APs). And not only that, but also light up another property next door!

Maybe we should have walked away. But, instead, I stated clearly why the solution would not work and made sure they were aware of a drawbacks. I’m don’t know if I would do this again, but I will definitely make even more of an effort in the future to have the customer deploy the right solution the first time around. It’s more cost effective and less stressful.

I don’t know if this is helpful to anyone, but I figured I’m not the only one who has had projects where your hands were tied. The moral of this story is - stand your ground. In this case it worked out because the customer realized the error and stepped up to do it right. But, make sure you fully layout the issues. Be respectful of the customer, but respect your skills and knowledge as well.

So, You Wanna Start a Business?

Estimated reading time: 9 minutes, 8 seconds. Contains 1829 words

I was referred to THIS post, written by Devin Akinon his first 6 months in business by @80211Alan. Really good stuff. I’ve been wanting to write something about my experiences as well, and after reading Devin’s post it spurred to write this one.

Actually, this started as a comment on his blog agreeing with his points, but then I realized it was getting long. So, I’m basically posting the response to his post here. So, here are things I’ve learned in my 5 years with CommunicaONE:



CommunicaONE is my 3rd attempt, and I’ve sucked at all of them except this last one. FINALLY realized that you can’t do EVERYTHING, business is NOT the same as engineering, and everyone is NOT your customer. Pick the things you CAN and WANT to do well, and then strive to be better than the rest at those SPECIFIC things.

I dropped voice, I dropped the server stuff, I dropped saying, “Sure, I’ll do that. How hard can it be?”, and FOCUSED on WLAN and networking. They complement each other and I can focus on learning to do them well. I’m not saying don’t learn about other things. I’m saying, as a SMALL business, focus your energies on what you can do quickly, efficiently, and well.



Devin hit the nail on the head here. No man’s an island. On this 3rd attempt I got a business consultant (who is now my partner). This was NIGHT and DAY different from my previous attempts. I had someone to hold me accountable, and help with areas I knew nothing about. Also, I got involved in the WLAN community and I can tell you that as the Good Book says, “Iron Sharpens Iron”.

"As iron sharpens iron,
so one person sharpens another.”


One last thing on this point, I send work to to other companies. It’s true. If a potential customer is not in my actual wheelhouse, or I don’t have the bandwidth to support them at that time, I will hook them up with a competitor. I’m crazy, I know, but I’ve built relationships with other people where we trust each other. I’m not stealing their clients, their not stealing ours, and we help each other out if one can’t do the project. Sometimes, it means referring a customer, other times it means we’ll sub each other out to fill in.

All I’m saying is, I’d rather have a good competitor that helps keep the skill-level up in our region than have a bunch of rinky-dink ones bringing everyone else down. 



DO NOT spend money where it’s not needed, but DO ABSOLUTELY spend money where it will do the most good. For example - DON’T waste money on fancy office furniture (or an office for that matter), especially if no one will ever see it! But, DO SPEND on say a quality office chair. You’ll be working there a lot and it makes a difference. Don’t spend on advertising, or Web designs, or for heaven’s sake don’t wrap your car in fancy graphics (“Kewl Kats Komputing - we’ll fix ANYTHING!”), but do pay for a Sqaurespace account (if like me, you’re no web designer), or another quality web host. You DO NOT want your Web site, or e-mail going down when you’re in the middle of a bid, or RFP. Post relevant content online, use social media, CALL PEOPLE. These are FREE.

Also, take this for what it’s worth, but if you need to learn (as I did/do) SPEND MONEY ON LEARNING! Not only do we need qualified WLAN pros out there, but word gets around. When you specialize, and put time/money/effort into becoming better at what you do - PEOPLE NOTICE.

Money cometh! Or, at least, opportunities will present themselves, because the people with the money (at least the customers you WANT) are looking for the best bang for their buck. Not the cheapest dude around (I ran 2 companies into the ground under that fallacy). But, in order to price yourself well you need to be worth it.

It’s important to understand, however, that you don’t make money by saving money. What I mean is - be frugal, but not stingy. I buy my team the most expensive MacBook I can afford. Not because we need fancy computers, but because they compliment our workflow, are phenomenally stable, are UNIX/BSD based, and the battery lasts forever. I don’t have time to be my own SysAdmin. This saves time AND money. I know this from experience.



You’re not IBM. You’re not Accuvant. You’re not Presidio. Be yourself. Your success DOES NOT have to look like theirs. I don’t have 50, 60, 100 people on staff (I don’t ever want to ), but I do have the people I WANT, who are easy to work with, and are passionate about what we do. Also, what works them may not necessarily work for you. Think about what you want your business to look like.

Here’s the nitty-gritty - DECIDE who your customer is. I mean actually THINK about what that looks like. Are they retail? Are they big? Are they small? Do they have multiple locations? Local companies (you hate to travel), or national firms (you love to travel)? Are they companies with strong IT departments, or weak ones? If they’re weak maybe you can be their outsourced IT. If they’re strong you come in as the high-priced specialist.

What I’m saying is everyone DOES NOT have to be your customer. If they are not a fit say no. Just because you ran sound for band in High School  does not mean you should be installing A/V at a Law firm. Focus your energies on finding customers that your company can best compliment.

Believe me, money cannot make up for a horrible customer/vendor experience. It’ll suck for you because you’ll feel slighted and they may tell others not so pleasant things about you. It’ll suck for them because they will not have gotten their money’s worth and feel ripped-off.

Nobody wins.



I personally have no interest in doing my own finances. I’m not good at it and I’ve already ruined 2 companies trying to save money here. This is one place I absolutely put money in to. Good bookkeepers are not cheap, but if they are good, they’re fast, and will make sure you’re not screwing yourself.

ABSOLUTELY, get a payroll service. Even if you can’t pay yourself much, or at all in the beginning, this will make sure you are compliant with State, and Federal taxes. This is from painful experience. If you’re not up to the challenge of keeping tabs on this stuff use a payroll service.

Personally, I use Quickbooks Online because it downloads all my transactions automatically, and I can access everything (invoices, payroll, balances) anywhere, even on my smartphone. I don’t have to be on top of making sure my Quickbooks and bank show the same thing. Also, I use their payroll because it’s pretty inexpensive and it integrates with QBO. It’s a monthly expense I’m willing to make because it saves me time and money.



When you start out you’re gonna be desperate for work. You have a mortgage to pay, probably kids, a spouse, a car payment, etc. But, hear this: When you start a business alone, YOU are the sales team, YOU are the marketing team, YOU are the support team, YOU are Accounts Payable AND Receivable.

If you are spending all your time doing small projects that suck your time away how will you: Get new clients? Market your company? Support your existing clients? Invoice your customers and pay your vendors? Remember, each of these things takes TIME. If we learned anything from INTERSTELLAR it’s that TIME IS A RESOURCE.

When you start a business you’re going to need time for: Learning/Training, Research, Selling, Marketing, putting together SoWs, Invoicing, Collecting. And how about actually DOING THE WORK? 

The hardest part of starting new is getting work and getting paid. Which brings me to the next bit…



Ok, I’m being a bit facetious here. What I am saying is that your time, your knowledge, your skill, has VALUE. Even if you don’t think so, it does. DO NOT be the guy that’s gonna win the market because you’re cheaper than the incumbent. Be reasonable, but don’t sell yourself short.

Here’s a secret - the customers you want ARE NOT looking at price. At least, not as the primary, or deciding factor. They are looking to see if you can get the project done, on-time, on-budget, with the least friction as possible. I’ve gotten jobs where we were BY FAR the most expensive option they looked at, but they chose us because they believed we brought the skills and expertise they needed. Also, believe it, or not, a higher rate makes you stick out - as in, “why are they so much more than company A?”. They assume (and it’s your job to make it TRUE) that you cost more because you are better. Plain & simple.



Despite what your friends/family/acquaintances say, you can’t just take time-off whenever you want because “you work for yourself”. I think it’s pretty insulting when people say how nice it must be to work for myself because I can do whatever I want. REALITY CHECK - if you want to be successful, if you want to make money, if you want people to take you seriously, you have to put TIME AND EFFORT into your business. I love what I do. I can’t imagine doing anything else, but I never for a minute forget I’m running a business.

You’ll be working a lot - especially in the beginning. More than a regular job. Why? Remember earlier, ” YOU are the sales team, YOU are the marketing team, YOU are the support team, YOU are Accounts Payable AND Receivable”? When do you think this stuff happens? If you’re working on projects who’s selling? Who’s invoicing? Who’s updating the Web site?

You are, my friend.

Be prepared to kiss your wife/husband, and kids goodnight after dinner so you can go through Quickbooks and make sure that your invoices are up to date, you sales taxes are paid, that the SoW you promised your customer will be in their inbox in the morning - is in their inbox in the morning. That’s all you.

You may be on the couch with a Firefly (the greatest show evar.) marathon playing in the background on the TV, but it’s all you. Unless you’re starting with a crack staff on day one - you will be busy.

Eventually, as your business grows, and you maybe bring on some people, as you figure out the best workflows, you’ll be able to take that month vacation, buy that fancy new car, pay off your kid’s appendectomy. But, in the beginning, you’ll be wearing a lot of ill-fitting hats.

Now, with clear eyes, and full hearts, get out there and make some business!

So, I got my ACCP

Estimated reading time: 4 minutes, 10 seconds. Contains 836 words

Today I passed my ACCP v6.0 Exam (Aruba Certified ClearPass Professional). I’ve been working on ClearPass Policy Manger (CPPM) since early 2013 and I have to say I really enjoy deploying this solution, but I totally forgot about the exam this Monday. I was a little nervous on Friday after I got back from the Wireless LAN Professionals Conference. I never test well, so even though I have several deployments under my belt I was still wondering how many questions I’d miss just from not reading them correctly, or pure nerves. Well, fortunately I passed with a pretty decent grade and can add another bunch of letters to my name!

I have to say CPPM is quite a large beast to tangle with and the first training class I took did not instill confidence. I remember taking this class in late 2012 and thinking after we were done that I spent a week on a product and I still don’t know anything about it. I mean I had an idea of what it did, but it felt more like a week-long sales training class than a technical deep dive.

So, along comes my first deployment and it’s for a large non-profit with a pretty complex network. Also, very smart people so it’s not like I could pull the wool over their eyes! :-) I honestly had no idea how to move ahead with this project. But, sometimes those are the projects that force you to focus and get the job done. And I did. I dug through some really limited not-so-great documentation (at the time), and even had support from the great Matt Sidhu, and Kaveh Mehrjoo at Aruba (Matt’s no longer there).

Fortunately, Aruba had figured out that their existing training was wholly inadequate for getting qualified implementers out on the streets. They started an advanced CPPM Workshop that was invite only (I think - could be wrong) to get partners up to speed. The class was a week long at their Sunnyvale campus. It was in the ClearPass engineering department so we literally had direct access to them. I mean we could call over the cubicles to them of we needed to. And of course they had several on hand just for the training. So, in the midst of the project we postponed for a week so I could go to the workshop.

The workshop consisted of all of us arriving for a briefing on Monday morning. The briefing was a faux school district that was presenting their requirements for the CPPM (802.1x, OnBoarding, Integrating Cisco WLC and IP Phones, Guest Access, OnGuard, AirGroup sharing, etc.). Our job - in groups of two - was to complete a successful working deployment by the end of the week. So, that’s what we did. We would start on each piece, have a break-out session to go over the deliverables and best practices and then, BOOM! You’re off!

It was the hardest training class I think I’ve ever taken. Most of us worked until 8, 9, sometime 10pm each night (Aruba was kind enough to leave the lights on for us) and we loved it! So, basically without using a customer as our lab (as I had begin to do) each of us were able to go through the pain and glory of a full deployment. Not only did I meet some awesome people there among the trainees and Aruba employees I got deep into CPPM in a way you normally can’t in a standard training course.

I have to hand it to Aruba. They were in a pickle. They had this fantastic product that was so deep, so powerful, so complex that partners couldn’t do the deployment on there own. Believe me - as a partner - professional services is where it’s at. If you have to bring in the manufacturer to deploy you’ve already lost a big chunk of your income (and stake) in the project. But, Aruba’s Advanced Workshop was exactly what they needed to do. A real “deep-dive” into a product where you not only get hands-on, but you get access to the people who built it, and work on it everyday. At the end of the week you really felt like you had a handle on CPPM. Not experts mind you, but at least you knew you were ready to tackle an enterprise project and come out the other end alive.

Coming back to the customer site afterwards was night and day. I had a mental handle on what we were doing. It wasn’t easy as it was still my first deployment, but at least now I had the tools to figure out what and how things needed to be done. Talk about trial by fire!

I would love to see this kind of approach across other products and vendors. Especially with deep, complicated products like ClearPass. I don’t know if this approach works with every product, but I can say I’ve never been to anything like that class and it would be a shame if I never did again.