What’s in a (WiFi) word?


If I need a new WiFi access point, should I get an 802.11n access point, one that follows 802.11 Clause 20 access point, or an HT access point.? Why not get them all?  That’s easy enough you see because they are all the same!

Let’s look at how this whole mess began.  The IEEE created the 802 family of standards in 1980.  You probably recognize 802.3 as Ethernet and maybe even 802.5 for Token Ring if you’ve been around like me.  The IEEE specifications that I deal with on a daily basis are 802.11 (WLAN) and 802.15 (WPAN).  Way back in 1997 the original 802.11 standard was born and soon followed by 802.11a and b in 1999.  802.11g was born in 2003 which used the same modulation as 802.11a and ported it to 5.0GHz.

By the time 2007 came around the IEEE decided to reboot the standard to 802.11-2007 by rolling up all the amendments (a,b,d,e,g,h,i,j) into this one.  The clauses are a little confusing and to make matters worse they changed in 2012 after a subsequent roll up.

Here are all the amendments (from Wikipedia) up until 2012…

  • IEEE 802.11-1997: The WLAN standard was originally 1 Mbit/s and 2 Mbit/s, 2.4 GHz RF and infrared (IR) standard (1997), all the others listed below are Amendments to this standard, except for Recommended Practices 802.11F and 802.11T.

  • IEEE 802.11a: 54 Mbit/s, 5 GHz standard (1999, shipping products in 2001)

  • IEEE 802.11b: Enhancements to 802.11 to support 5.5 Mbit/s and 11 Mbit/s (1999)

  • IEEE 802.11c: Bridge operation procedures; included in the IEEE 802.1D standard (2001)

  • IEEE 802.11d: International (country-to-country) roaming extensions (2001)

  • IEEE 802.11e: Enhancements: QoS, including packet bursting (2005)

  • IEEE 802.11F: Inter-Access Point Protocol (2003) Withdrawn February 2006

  • IEEE 802.11g: 54 Mbit/s, 2.4 GHz standard (backwards compatible with b) (2003)

  • IEEE 802.11h: Spectrum Managed 802.11a (5 GHz) for European compatibility (2004)

  • IEEE 802.11i: Enhanced security (2004)

  • IEEE 802.11j: Extensions for Japan (2004)

  • IEEE 802.11-2007: A new release of the standard that includes amendments a, b, d, e, g, h, i, and j. (July 2007)

  • IEEE 802.11k: Radio resource measurement enhancements (2008)

  • IEEE 802.11n: Higher-throughput improvements using MIMO (multiple-input, multiple-output antennas) (September 2009)

  • IEEE 802.11p: WAVE—Wireless Access for the Vehicular Environment (such as ambulances and passenger cars) (July 2010)

  • IEEE 802.11r: Fast BSS transition (FT) (2008)

  • IEEE 802.11s: Mesh Networking, Extended Service Set (ESS) (July 2011)

  • IEEE 802.11T: Wireless Performance Prediction (WPP)—test methods and metrics Recommendation cancelled

  • IEEE 802.11u: Improvements related to HotSpots and 3rd-party authorization of clients, e.g., cellular network offload (February 2011)

  • IEEE 802.11v: Wireless network management (February 2011)

  • IEEE 802.11w: Protected Management Frames (September 2009)

  • IEEE 802.11y: 3650–3700 MHz Operation in the U.S. (2008)

  • IEEE 802.11z: Extensions to Direct Link Setup (DLS) (September 2010)

  • IEEE 802.11-2012: A new release of the standard that includes amendments k, n, p, r, s, u, v, w, y, and z (March 2012)

Here is a handy little translator that explains further changes in the clauses from 2007 to 2012:



So that explains some things that are usually a little cloudy.  IEEE specs are not the only area in the wireless arena that can be confusing.  People’s definitions of Guest and BYOD often vary.  My understanding is that Guest is usually a specific type of BYOD, whereas BYOD implies that the user is an employee but owns their own mobile device.


Remember that networking is very technical stuff and knowing terms and what acronyms stand for can be half the battle.  I will spare you all the discussion on MPDU versus PSDU, I guess that will be a future blog.


Which wireless certification is right for you?



You want to get certified in the WiFi field, but which one is right for you?  Well Clark Kent will help you decide.  I presently have certifications granted by 3 of the biggest WiFi vendors and 3 vendor-neutral certifications.  First lets look at the biggest vendors out there.  Cisco bought Meraki in 2013 so that kept them in the top slot.  HP bought Aruba keeping them at a strong #2.

CWNP was founded by Planet3 Wireless but I think is simply CWNP now.  There are a total of 5 tests in the certification track.  CWTS, CWNA, CWSP, CWDP, CWAP

CWNP certs


I have taken all of these (except I skipped the CWTS)  I have passed all the exams except the CWAP which I am presently working on.  These are great exams that really dig into RF and 802.11.  They also test your knowledge of “the tools of the trade” like packet analyzers and spectrum analyzers.  The tests vary in price from $150 to $225.  It is good idea to get one of the bundles from CWNP.  They offer a bundle with practice exams, textbook, and exam voucher for $325.  At present there are only 163 CWNE’s in the world.  This certification is real deal.  Pass the CWNA and the 3 Professional level certs and you are eligible to apply for the CWNE.  After publishing WiFi related material and verification of employment and good character, the CWNP board will grant you CWNE status.

More info at CWNP website:          www.cwnp.com/certifications/

Cisco has a Wireless certification track which follows the same model as their other tracks take the CENT entry-level networking exam based on routing and switching.  Then take the CCNA.  To achieve the CCNP you will need to pass 4 exams.  The exams are based on Site Survey, Voice/QoS, Security, and Mobility (this encompassed RTLS, WNMS, and MESH).  Once you achieve this (which I have) you can go for the CCIE, that is only if you are a masochist.  I have passed the CCIE written, but failed the CCIE practical exam twice.  I am not 100% sure but I think I will subject myself to this again in the future. There are also very few Wireless CCIEs.  Cisco does not publish the exact number but it is around 150 last it was referenced.  The Cisco track is very vendor-specific and not nearly as deep as the CWNP in IEEE and RF fundamentals.  The exams vary from $125 – $250 for associate and professional level.  The CCIE written is $400 and the lab is $1600.

Cisco wireless certification page:


Aruba (an HP company) offers a similar track as Cisco to advance in the Aruba WiFi realm.  Aruba offers the ACMA, ACMP, ACMX and ACDX.  I presently hold the ACMA and the ACMP.  I would say that the Aruba is a hybrid of the Cisco and CWNP tracks as it is vendor-specific but strong on standards as well. Aruba’s exams are all $125 except for the expert level exams, they are $1000.  There is another track that is interesting and helpful; it is for Aruba’s ClearPass.  ClearPass is an access management platform that is great for BYOD and Guest Access as well as TACACS and RADIUS.

Find out more from Aruba here:


Meraki also has a certification called the CMNA.  It is based on taking a class and completing the labs and an exam.  I did complete this certification but it is in a different class of certs.  It is not taken at a Pearson Vue and it is free of charge.  Many of the vendors have this type of certification.  I have done these for Enterasys, Symbol, and Motorola in the past.  In general certifications are a great way to further your knowledge and education while increasing your potential for earning more.  Good luck and Happy studying!



How do Bluetooth and WiFi coexist?


Bluetooth and WiFi share a frequency band.  So how do they peacefully coexist?  WiFi on the 5.0 GHz range avoid Bluetooth altogether.  However what strange magic allows them to operate side by side?

 Both Bluetooth (802.15) and WiFi (802.11) share an 87 MHz swath of the ISM band.  Bluetooth uses Frequency Hopping Spread Spectrum (FHSS) and jumps around 79 different 1 MHz channels.  WiFi uses Direct Sequence Spread Spectrum (DSSS) and uses a 22 MHz channel.  There are 11 channels in the ISM band but they overlap each other.  So properly implemented networks will be implemented on one of three non-overlapping channels (1,6, and 11).

So when a Bluetooth radiator hops to channels within the same 22 MHz channel the WiFi stations are communicating, there is interference.  How “loud” the signals are and how close the radiators determine how much interference occurs.  Typically the latest hardware of both WiFi and Bluetooth operate harmoniously.

When Bluetooth does experience significant interference it hops to the next channel in an attempt to avoid the interference.  Bluetooth is similar to the now extinct protocol Token Ring (802.5) which used collision detection.  Wifi, unlike Bluetooth and Token Ring acts more like Ethernet (802.3).  Both Ethernet and WiFi use Collision Detection to combat collisions.  The competing stations determine a random backoff time and retry communication.  In addition 802.11bg networks with rate shift to slower data rates in an attempt to lower the BER (Bit Error Rate).

There are situations where harmonious coexistence will not be possible.  I did work for a well-known  electronic gaming company.  There was a floor with scores of quality control analysts with 3-4 gaming consoles all of which necessarily use Bluetooth.  Designing a WiFi network to operate efficiently in this environment was certainly a challenge.  Depite copious contention both continued working quite well.  Kudos to the IEEE (who set he standards for both 802.15 and 802.11).

 To learn more check out the following videos…

geekyranjitexplains (Aug 8, 2013). Understand WiFi Routers Basics – Part 1 Geekyranjit Explains. Retrieved from


profgustin (Apr 9, 2012). Android – Intro to Bluetooth. Retrieved fromhttps://www.youtube.com/watch?v=M5_EJ27xjMU



RF hero MIMO converts multipath to good


By now you have probably heard about 802.11ac which boasts data rates up to 1.3 Gbps.  If you haven’t I imagine you know about 802.11n.  So what makes these IEEE standards so good?  Well for one thing the “N” standard introduced Multiple Input/Multiple Output or MIMO.  Now hold that thought for a moment…

Back in the days prior to 2009 we had this ugly problem called Multipath.  To an RF signal there are many forces of evil working against successful transmission.  Reflection (RF Energy bounces off a smooth surface predictably), Diffraction (waves bend around sharp objects), and Scattering (RF Energy reflecting off the texture of a varied surface like stucco);  these are just some of the nefarious foes RF faces daily. Multipath is how RF energy waves react when parts of the wireless transmission meet at the antenna with differences in time and geometry.  Back in the beginning of the millennium multipath was a problem that was addressed by using antenna diversity.

If there was really a superhero called MIMO it would be Dr. Greg Raleigh.  The Qualcomm innovator was responsible for the development of MIMO which Qualcomm defines as follows: “MIMO systems divide a data stream into multiple unique streams to take advantage of multipath signal reflections to actually improve radio transmission performance.”  So when MIMO combines with other enhancements like TXBF, STBC, and SGI we see data rates really sky rocket.  To find out more about 802.11n and 802.11ac follow the links below.










CHROMEBOOK, is it WiFi Kryptonite?


Google proclaims that their Chromebook “…is for everyone.” The Chromebook first shipped in 2011.  And actually there have been mixed reviews ever since.

Chromebook is supposed to be a reasonably priced alternative to the laptop and the i-Pad.  It runs on Chrome OS and is designed for Internet access and data in the cloud.  Picture a creature that exists between a dumb terminal and a full-fledged PC.  The Chromebook is manufactured by numerous companies such as Acer, Dell and Samsung.  It has a single USB port and limited programs that run locally: music player, photo editor, and document viewer.  All other applications are available for purchase and download from Google Play.

Because the Chromebook is simple is does boot quickly.  The price is cheap and Google claims “…the proprietary architecture eliminates the need for Anti-virus software.”  I have yet to encounter a virus in my limited interaction with this platform.  However where this simplicity is attractive for younger and senior users alike, if you are a technie or just like to tweak stuff the Chromebook may not be for you.

From a WiFi connectivity prospective the Google Chromebook does have challenges.  The area in which we have seen the most traction for the Chromebook is in schools K-12.  In the classroom Chromebooks will first try to log-on and if the connection to the Google cloud is not operating properly connecting can be quite frustrating.  Also there are limited settings available in the wireless connections for customization.  Typically in schools there are many devices competing for the wireless medium so a strong underlying WiFi design is crucial.

When possible it may make sense to limit Chromebooks to single band either 2.4 or 5.0 GHz.  This will reduce its choices and eliminate selecting one over the other.  Also use a single SSID profile so it cannot switch to other SSIDs.  Another helpful tip I discovered is using Google’s DNS servers as they are the most accurate for the Google/Chrome services.

I think the Chromebook definitely has its place and that is chiefly in k-12 schools.  I believe that as the product matures it will operate more effectively.  In the meantime here are some resources that you may find helpful.

Chromebook troubleshooter

Google Support




ARUBA NETWORKS 270 Series Outdoor Access Points


Posted originally on July 7, 2014 By: John Busso, CISSP, ACMP, ITIL

Aruba AP270 Highlights

  • 802.11ac in 5.0 GHz band with up to 1.3 Gbps data rate
  • 802.11n   in 2.4 GHz band with up to 600 Mbps data rate
  • AP275 has an integrated MIMO Omnidirectional antennas
  • AP274 allows for external MIMO N-type antennas
  • Aesthetic design mimics common fixture for lighting/cameras
  • NEMA and IP-rated (IP66/67) for harsh environments
  • ClientMatch enabled to leverage 802.11k,r,and v standards
  • Flexibility for use as campus, remote or independent AP
  • 48VDC 802.3at-compliant or  100-240-Volt AC Power

I have been designing and implementing wireless networks since the ratification of 802.11 (yes prior to 802.11a or b).  I have seen many technologies come and go, such as WiFi using 900 MHz and Free Space Optics (FSO), which was essentially wireless using lasers as opposed to microwaves.  Aruba gets it right again improving on their existing outdoor wireless access point (see full product line here).  The AP270 series outdoor access point is a purpose-built, state-of-the-art device that will survive extreme conditions and anticipated wireless standards, making it “future-proof” for years to come.

To understand what makes the AP270 such a great WiFi access point we need to look at a few key factors: being future-proof, easy install and manage, flexible, and high-performing.

  • AP270 access points are future-proof because they are fortified against extreme weather and environmental contaminants.  The AP270 can operate between -40° F and  150° F.  It withstands humidity in a range of 5%-95%.  The access point can withstand up to 165 mph winds.  The Aruba 270 series AP is also future-proof because it uses the latest IEEE specification 802.11ac .
  • This outdoor access point is easy to install with only two mounting template one for wall-mounting and one for pole-mounting.  The mounting kits come in long and short depending on your specific application. Ethernet and serial console access makes configuring the AP270 easy and flexible.  The AP275 comes with integrated internal 3×3 MIMO antennas.  The AP274 can utilize any N-type antennas needed for your application .
  • Managing Aruba APs is easy and flexible because one can use the virtual controller resident on iAPs, controllers for campus and remote APs, or AirWave network management system for all of the above.
  • Aruba’s AP274/275 Access Points are high performing 802.11ac Access points that leverage several technologies.  Transmit Beam Forming is used for increased reliability in signal delivery.  Low Density Parity Check allows for high-efficiency error correction and increased throughput.  Maximal Rate Combining improves receiver performance.  Advanced Cellular Coexistence is employed to minimize interference from cellular systems.  To improve downlink RF performance the AP270 uses Cyclic Delay Diversity.

So to sum it up, Aruba’s AP274’s and AP275’s are good looking, easy to install, flexible, and high-performing.  Remember that they can be used as APs, iAPs or RAPs.  You can use the turnkey AP275 with its integrated antennas or select the AP274 when antenna tuning is desired.  Aruba offers all this at a list price of$1595 USD for the AP274.  For more information Click Here


WiFi Superman’s alter ego

RTLS: BIG BROTHER IS WATCHING, but he is helping out too.


Posted by (originally May 20, 2014): John Busso

Real Time Locating Systems are no longer a secret.  For many years now companies like Ekahau, Pango and AeroScout have been selling tags to help track devices that do not have a wireless card to communicate via WiFi (802.11).

Sure tagging an item is great to track it along the supply chain, it is great to tag a heart monitor and retrieve it before it leaves the hospital for the laundry wrapped up in the  bed sheets.  But when your company asks you to wear a badge that tracks you  that is when you become very interested.

First off do not worry.  You can already be tracked by your smartphone, tablet and laptop.

The reality is that this can provide much value in the areas of supply chain, workflow, and shrinkage.  Aruba believes so strongly in RTLS and its ,many uses that it bought the company Meridian:



Industry experts believe that the proliferation of Bluetooth Low Energy (BLE) exciters will accelerate the accuracy and adoption of RTLS technology.  Click here to learn more about how Aruba and RTLS can work together for you.


Why do you need 802.11ac?

me                 REASONS YOU NEED 802.11AC

Originally posted 14 February, 2014

More, more, more

  • There are more devices which cries for efficiency
  • There are more applications which demands higher performance
  • There is more multimedia which necessitates getting users off and on quicker

Better coverage

  • Thanks to explicit transmit beam forming  your coverage is much more effective

Backwards compatibility

  • 802.11ac is backwards compatible for all other IEEE 802.11 standards
  • Even older chipset will benefit from many of the enhancements of 802.11ac


  • If you do not have 802.11ac then you will not have any visibility into emerging 802.11ac threats
  • Even if you are not ready to rip and replace your legacy system you could benefit by adding some 802.11ac APs as monitors.

To read more on this topic go here: