CTS 026: Channel Overlap

Channel Overlap

I tackle the topic of channel overlap in wireless. Some people may refer to this as co-channel interference. Others use the term co-channel cooperation or even co-channel contention. The latter of the two are more accurate terms to use.

But first, lets talk about what channel overlap is. I’m referring to two or more access points providing service for the same area on the same channel.

Why is this a big deal? When two or more access points hear each other on the same channel it becomes the capacity of one access point. This is because of the contention the access points must face when vying for air time. It creates more overhead which leads to lower throughput and more latency.

What are some ways to mitigate channel overlap?

The only ways to mitigate channel overlap involve proper planning which includes a good channel re-use plan, pre-deployment surveys to determine what channels are already in use in your deployment area, and a validation survey to verify any channel overlap.

In addition to the above steps, some other ways to mitigate channel overlap include:

  • Turning off 2.4 GHz radios
  • Use directional antennas
  • Use 20 MHz channel widths

Listen to the episode and let me know what your thoughts are in the comments below.

Links and Resources Mentioned

Thanks For Listening

I hope you enjoyed this episode on Channel Overlap. Leave a comment below if you have any feedback or additional tips you’d like to leave for other listeners.

Thanks to those who have subscribed to the podcast, reviewed, and shared on social media. I really appreciate your support for the show. If you haven’t yet, please take a moment to leave a [review]

CTS 025: Wireless Certifications

Image of wireless certifications
What certifications are available out there for wireless network engineering? When I did some research, I found that there is really one authority on wireless certifications.

This episode is about identifying vendor-neutral certifications and vendor-specific certifications.

I talk about some of the reasons why one may want to be certified in wireless. Not everyone gets certified and its definitely not an absolute requirement to hold a certification.

Additionally, many will fail certification exams. I have failed a couple in my career. Just don’t let that get you down. Keep studying and stay determined.

Why get certified?

  • Get your foot in the door
  • Explore a career roadmap
  • Learn / grow expertise
  • Show value
  • Promotion / salary increase
  • Stay current
  • You have to (VAR or MSP)


  • CWNP – 6 certifications
    • CWTS (Certified Wireless Technology Specialist)
      • Entry level for sales, project managers, and those new to WiFi.
      • Good for a lifetime
    • CWNA (Certified Wireless Network Administrator)
      • Understanding RF, site surveys, etc.
      • RF fundamentals
      • Antenna concepts
      • Standards
      • Protocols
      • MAC and PHY layers
      • Architecture
      • Security
      • Valid for 3 years.
    • CWAP (Certified Wireless Analysis Professional)
      • Must have CWNA
      • For those who want to know how to analyze, troubleshoot and optimize WiFi.
      • Getting down to the nitty gritty.
      • PHY layer frame formats
      • MAC layer frame formats
      • Frame exchanges
      • Spectrum analysis
      • Protocol analysis
      • Troubleshooting
      • Valid for 3 years.
    • CWDP (Certified Wireless Design Professional)
      • Those who want to properly design WiFi.
      • Requirements analysis
      • Site surveys
      • Design
      • Deployment
      • Validation
      • Need CWNA.
      • Valid for 3 years.
    • CWSP (Certified Wireless Security Professional)
      • Prove your knowledge in WiFi security.
      • Intrusion and attacks
      • WIPS
      • VPNs
      • Security design models
      • Encryption
      • Need a CWNA.
      • Valid for 3 years.
    • CWNE (Certified Wireless Expert)
      • Not an exam.
      • Go through an application process.
      • Written paper.
      • Need all certifications.
    • Average Salary
      • CWNA – $71,250 – $105,750
      • CWNE – $157k – $262,500
  • Comptia
    • Mobility+ (MB0-001)
    • Vendor neutral
    • Focuses on mobile device management, troubleshooting, and security.
    • Includes not just wifi but CDMA, TDMA, GSM, WiMAX, LTE, and others.
    • Covers 802.11
    • RF characterstics
    • Antennas
    • Site surveys
    • Network infrastructure
    • And OSI model

Vendor Certifications

You can go for vendor specific certifications from vendors such as Cisco, Aruba, and Ruckus. While these certification tracks will teach you some WiFi specific technology, they are aimed more towards configuring a specific vendors equipment.

The key takeaway here is that you still need a solid foundation in wired networking and wireless networking. Because of this I recommend going for the CWNP certifications first. They are vendor neutral.

  • Cisco
    • CCNA Wireless
      • Entry level for the Cisco Wireless track
      • Configuring, implementing and support Cisco wireless
      • Start diving into Cisco wireless architecture
      • Such as Cloud, autonomous, and controller based models
      • Introduction into CAPWAP
      • Need a CCENT
    • CCNP Wireless
      • Four exams
      • CUWSS (Cisco Unified Wireless Site Survey)
        • What you need to know leading up to a site survey
        • What to plan for
        • How to conduct a site survey – and you’ll probably dive into Cisco specific products
        • Perform an assessment
      • IUWVN (Implementing Cisco Unified Wireless Voice Networks)
        • Getting into designing and implementing wireless networks for VoIP.
      • IUWMS (Implementing Cisco Unified Wireless Mobility Services)
        • Location based services such as DAS and RFID.
        • AP groups
        • High availability
        • Cisco specific technologies such as Flexconnect
        • Using logs and debugs
        • RF tuning
        • MSE architecture
        • Mesh
        • Cisco WCS
      • IAUWS (Implementing Advanced Cisco Unified Wireless Security)
        • Client device security
        • NAC – Network Access Control
        • Securing connectivity services
        • Guest access
        • Policies
        • IPS/IDS
        • Advanced Security Platforms
    • CCIE Wireless
      • Written and a lab
      • List of objectives for the written portion
      • Configuring and troubleshooting
      • Then fly out to Cisco to do the lab portion.
      • Rigorous
  • Aruba
    • ACMA (Aruba Certified Mobility Associate)
      • Controller model familiarity
      • AP models
      • Provisioning of APs and configuration
      • Management
      • RF Management
      • Single controller environment
    • ACMP (Aruba Certified Mobility Professional)
      • Those working in complex environments
      • Multiple controllers
      • Same topics but deeper understanding
    • ACMX (Aruba Certified Mobility Expert)
      • Validate knowledge in implementing and troubleshooting large WiFi networks.
      • ACMP is required
      • Just some of the topics – Arubas mobility OS
      • Redundancy
      • Spectrum monitoring
      • VoIP
      • Captive portals
      • Troubleshooting
    • ACDX (Aruba Certified Design Expert)
      • For the architect of large environments and remote offices.
      • ACMP required.
      • Designing redundancy, RF, QoS, security, authentication
  • Ubiquiti – Thanks Spencer!
    – UBWS (Ubiquiti Broadband Wireless Specialist)
    – UBWA (Ubiquiti Broadband Wireless Admin)
    – UEWA (Ubiquiti Enterprise Wireless Admin)
  • Other Certifications related to wireless
    • Wireshark
    • Ekahau
      • ECSE – Ekahau Certified Survey Engineer
        • Go through a class which is taught by Keith Parsons or Devin Akin.
        • RF fundamentals
        • Predictive designs
        • Pre- and post-deployment site surveys
        • Troubleshooting
        • Spectrum analysis
        • Reporting
    • Security Centric
      • OSWP (Offensive Security Wireless Professional)
        • OSWP focuses on conducting reconnaissance on wifi networks, avoiding detection, cracking security, implementing attacks, and all that good hacker stuff.
      • GAWN (GIAC Assessing and Auditing Wireless Networks)
        • Targeted towards auditors, network admins and pen testers responsible for security wireless networks.
        • Focused on security mechanisms, tools used to exploit weaknesses, analyze wireless networks
        • Fuzzing, DoS attacks, attacks of authentication and encryption methods, rogue networks, auditing. Good stuff.

Links and Resources Mentioned

Thanks For Listening

Thanks for listening to this episode on Wireless Certifications. I want to know what you think about certifications. Does certifications help you in your career? Leave a comment in the show notes http://www.cleartosend.net/25

Lastly, I want to thank some new reviewers:

  • SweetTeaJunkie says

Great Podcast! Rowell knows wi-fi. I’ve been listening as I work my way through the CWNA and his knowledge has been very helpful. Thanks!

  • Rybo1199 says

Great Podcast! Keep up the good work!

  • therealswy says

Your podcast app should RTS CTS! Packed with real world product info, interviews with important players in the WiFi world and practical knowledge, CTS has earned a top seat in my podcast queue. With a consistent release schedule, solid production quality and a focus on providing knowledge over chit-chat with others, I consistently learn something from Rowell’s podcast. Anyone the admin who has “WiFi” among the long list of tech responsibilities up through those who focus solely on large deployments can learn from CTS”.

  • JasNH1846 says

Excellent resource for WiFi info! This is the podcast I have been looking for on the wireless topic. The format is great its not too long its not too short, the expertise level of the guests and the host is excellent.

Thank you guys for the 5 star reviews! I greatly appreciate it! If you would like to leave a review please head over to http://cleartosend.net/review. Your feedback is most appreciated.

Once again, thank you for joining me on this episode on wireless certifications. Go out there, build great wifi networks, and keep being awesome. I will see you on the next episode. Over and out.

CTS 024: Channel Planning Around Neighboring WiFi Networks

Image of SSIDs on various channels.

In this episode, we have a listener question from Steve Yuroff who asks:

When you have a business with neighbors (particularly residential apartments) where WiFi bleeds over, how do you do channel selection when the neighboring channel use can be an ever changing issue? Networks come and go, a new one could have popped up since I last surveyed.

Very good question Steve. This is definitely a challenge to work with when you have neighboring WiFi signals propagating into your environment.

The thing about WiFi is that it is an iterative process. You’ve probably heard this before because I’ve taken it from Keith Parsons and Andrew Von Nagy.

That means you gather requirements, plan, do your predictive surveys, deploy, validate, and optimize. That is a repeatable cycle. Channel planning is part of that process.

In the United States we have 3 non-overlapping channels in the 2.4 GHz spectrum and 25 non-overlapping channels in the 5 GHz spectrum.

When two or more access points are transmitting and receiving on the same channel it causes errors and retransmissions. It is the same as having the capacity of one access point because all devices, including the access points, are contending for air time.

WiFi is a half duplex medium in which one device can communicate at a time.

To answer Steve’s question, I use a combination of tools to select the best channels to avoid co-channel interference. The tools are listed below in the resources section.

Specifically in my experience, I am using Ekahau Site Survey to conduct pre-deployment or validation surveys to determine where access points are heard on a floor plan. I have also used spectrum analyzers such as Metageek’s Chanalyzer to gather more information such as channel utilization.

If you’re working with a limited budget, check out Metageek’s InSSIDer Office. Another option that isn’t ideal would be using Adrian Grenado’s WiFi Explorer but taking note of where signals are heard and on what channel, on a floor plan. The caveat here is that you are doing this on your device’s built-in WiFi card. Results could be different for another device.

Links and Resources Mentioned

Thanks For Listening

I’m interested in how you plan channels around other WiFi networks that propagate into your environment? Let me know in the comments below!

CTS 023: Jason Hintersteiner Part II – Small & Medium Business WiFi

Male working on his Macbook Air.

This is Part 2 of my interview with Jason Hintersteiner joins the Clear To Send podcast to talk about how he got started in WiFi after the thought of having to move to Europe for his employer. From there Jason brings up his experiences working with small & medium business WiFi.

If you haven’t listened to Part I yet I suggest starting there first.

In Part II, Jason talks about becoming CWNE and his tips for those pursuing CWNE certification. I also ask him about starting a consulting firm and what challenges come from becoming an entrepreneur.

Links and Resources Mentioned

Part I – Jason Hintersteiner
@emperorwifi – Follow Jason on Twitter
www.emperorwifi.com – Jason’s blog
www.imperialnetworksolutions.com – Jason’s consulting firm
Tamograph – Wireless Site Survey software
CommView – Network Analyzer, same makers of Tamograph
Wireshark – Free network protocol analyzer
CWNE – Certified Wireless Network Expert certification from CWNP

Thanks Listening

This completes the two part interview with Jason Hintersteiner who provided his experiences and challenges with working with small and medium businesses.

If you enjoyed this episode, please share it on social media with the share links below. I would also highly appreciate it if you provided a rating and review of the podcast on iTunes to help expose the podcast to new listeners.

Thank you for listening and tune in for the next episode!

CTS 022: Jason Hintersteiner Part I – Small & Medium Business WiFi

SMB WiFi text over a desk

Jason Hintersteiner joins the Clear To Send podcast to talk about how he got started in WiFi after the thought of having to move to Europe for his employer. From there Jason brings up his experiences working with small & medium business WiFi. This is Part I of a two part podcast interview.

The SMB space requires a different approach to WiFi compared to a large enterprise or large educational institution. While the process might be different, one thing is certain – Jason and I agree that a wireless professional must know the basics or foundations of wireless before designing, installing and troubleshooting a wireless network.

I ask about the tools Jason uses on his Windows laptop and what his design methodology is, such as 80, 40, and 20 MHz channel widths.

Links and Resources Mentioned

@emperorwifi – Follow Jason on Twitter
www.emperorwifi.com – Jason’s blog
www.imperialnetworksolutions.com – Jason’s consulting firm
Tamograph – Wireless Site Survey software
CommView – Network Analyzer, same makers of Tamograph
Wireshark – Free network protocol analyzer
CWNE – Certified Wireless Network Expert certification from CWNP

Thanks For Listening

Thanks for listening to this episode. This is Part I of the interview with Jason Hintersteiner. Stay tuned for Part II as we wrap up with Jason.

If you enjoyed this episode, please share it on social media using the share buttons below.