LTE-U and 5 GHz Wi-Fi

LTE has an unlicensed version called LTE-U that uses the 5 GHz U-NII-1 and U-NII-3 bands used Wi-Fi.  The FCC has authorized the first of the LTE-U devices https://www.fcc.gov/news-events/blog/2017/02/22/oet-authorizes-first-lte-u-devices.    What are the implications of this standard?  Will Wi-Fi start having problems on the patio of your favorite coffee shop forcing you to go inside to get a reliable signal?   There is a coexistence standard http://www.lteuforum.org/uploads/3/5/6/8/3568127/lte-u_coexistence_mechansim_qualcomm_may_28_2015.pdf but of course, there is the standard and the actual performance as implemented by device drivers.   

By the way it appears that Wi-Fi vendors such as Aruba, Broadcom, Cisco, Ruckus have been involved http://www.lteuforum.org/uploads/3/5/6/8/3568127/lte-u_introduction_may_28_2015.pdf but I do not know how much of a conclusion to draw from that.    There has been testing against 802.11n http://blogs.cisco.com/sp/cisco-wifi-wi-fi-service-provider-lte-u-by-any-other-name-is-licensed-assisted I have not yet found a reference for testing against 802.11ac that has useful information.  I hope someone can give a better more recent reference that is more reassuring. 

An Aruba networks document http://www.arubanetworks.com/assets/wp/WP_WiFiFirst.pdf also gives me pause, “Because it is a duty-cycle based solution, an LTE-U base station effectively takes control over its channel by force under control of a licensed operator, leaving it up to Wi-Fi to sense when the duty cycle is off.”

I welcome your comments.  

Cool Wi-Fi!

Cool Wi-Fi, or should I say cold Wi-Fi?

A local grocery store left the access panel open to the refrigerated area.  Usually I worry about the other end of the temperature range, but if this is a 3700e model http://www.cisco.com/c/en/us/products/collateral/wireless/3700-series-access-point/data_sheet_c78-729421.html and it looks like the AP is still in spec for temperatures at or just below the freezing point of water.  Of course that raises other questions such as why do they need Wi-Fi in their refrigerator case?   How well do inventory bar-code guns work in that temperature range?

This wireless was foiled

As a wireless person I receive occasional questions about electromagnetic radiation which I just referred to the Environmental Health and Safety department.  Some pictures below show where someone appears to have taken matters into their own hands, but even without the foil I doubt this person was hitting any exposure limits from the AP https://www.fcc.gov/general/radio-frequency-safety-0

Personally it is a little funny that some people worry about exposure from APs, yet will hold a cell phone right next to their head for an extended period of time.

Super Bowl 50

An interesting thing about where I work is that am within sight of Levi Stadium.    Here is a picture I took from the building a few days before the Super Bowl.

The Goodyear Blimp was already flying around the area.   If you are in the area and have a scanner then there are some frequencies you could try to listen to the blimp http://wiki.radioreference.com/index.php/Blimps

While I do not have any predictions as to which team will win, it is a safe bet that a record amount of  data will be transferred over wireless networks.   http://www.techrepublic.com/article/super-bowl-50-to-showcase-new-tech-shatter-bandwidth-records/

This what I saw at the Phoenix Airport last year.  Talk about close!

  

Radio Shack

If you are also into the RF part of communication make sure to stop by Radio Shack before it is too late.  Closing of the stores represents a change in purchasing options, but in the short run it also means some good prices.  I bought some PL259 connectors for about a dollar each today.

Wireless Networking Videos

If you are working on the CCNA or CCNP wireless or any of an number of other wireless certifications such as http://www.cwnp.com/.  It is useful to know that a set of videos by Jerome Henry were just released by Cisco Press.  (Jerome Henry is a well known person in the wireless world.  He has both a CWNE and a CCIE wireless.)  The videos are called Wi-Fi Configuration, Deployment and Troubleshooting LiveLessons True there is material available for free on YouTube, but the quality varies greatly.  

At this point I am about half way through the videos, and would recommend it as a good use of time for anyone in wireless networking.

A different type of rogue wireless device

If your job involves tracking down rogue wireless devices, make sure to look at the vending machines in the area.  Our fancy new Coke machine turned out to have a wireless connection.  It takes something like this http://www.flukenetworks.com/enterprise-network/network-testing/AirCheck-Wi-Fi-Tester to be sure for a specific case of your site, but as you can see from a this reference http://mandetech.com/2010/12/16/odyssey-software-enabling-coca-cola-freestyle-machines/ that the capability does exist.

Wireless in stadiums and other large venues

With the memory of the Super Bowl fresh, it is natural to think about wireless in a stadium.  The Levi stadium in Santa Clara has a wireless network that is nicely done.  It was done by Aruba networks with APs under the seats to deliberately limit the cell size http://www.mobilesportsreport.com/2014/08/stadium-tech-report-aruba-networks-chief-designer-on-building-the-ultimate-stadium-network-at-levis/   In other cases absorption from bodies is bad, but in this case it is good.   http://www.arubanetworks.com/wp-content/uploads/stadiumRFfund.pdf.  When planning your own implementation make sure to review some of the wireless vendor solutions already out on the web.  For the case of Aruba it may be found at http://www.arubanetworks.com/solutions/lpv/

RF Part of Wireless Networks

Here are some links helpful for the RF part of wireless networks

Cool Links - Microwaves101.com

Microwave design articles, applications, and high-frequency design techniques for microwave and wireless engineer

Microwaves101.com - A practical resource covering the fundamental principles of microwave design

RF Components & Test Equipment - everything RF

RF Parts Company™ Amateur Radio Catalog

RF, wireless product design and test, RF-analog hw, sw - octoScope

Smith Chart Basics - Microwave Encyclopedia - Microwaves101.com

Wireless Net DesignLine Online Research Library for the Wireless Engineering Community

http://www.arrl.org/

CWDP & CWAP - Enterprise Wi-Fi Design & Analysis

Netflix stops working when I make popcorn

Sometime back Netflix stopped working when I made popcorn in my microwave.  The video would run for a short period of time from the buffer, but then would not start up again until the microwave stopped running.  Being a wireless person my media player used for Netflix has a wireless connection to my router.  Here are some things to consider in a situation like this:

• Is the wireless media play capable of using 5 GHz instead?  (In my case the media play did have 5 GHz but would only connect on 2.4 GHz given the distance to the wireless router)
• A option for 2.4 GHz, that is channel 1-14, is to change channel.   (In the US it is channel 1-11)  The question is will that channel be any better.  A useful thing to actually look at the radio signals is a spectrum analyzer.  If you have an iPhone an option is this https://www.oscium.com/spectrum-analyzers/wipry-pro  which lets you see the radio spectrum in the area.  In the case when I stood in front of my microwave I saw this.  
  
    Notice the peak around channel 11.  The conclusion in this case is to use channel 6 or even better channel 1 to get away from the microwave oven interference.
• Another option if you can not have your router near your media play is to use something like this http://www.amazon.com/Linksys-Powerline-Network-Adapter-PLEK400/dp/B006JG5S6K to make a connection between your router and your media player.  This device sends the wired network traffic over the power lines of your house.

The ISP said the connection speed was upgraded, so why isn't my wireless faster?

Jan 10, 2015
Recently my ISP (internet service provider)  upgraded my data rate but there was no noticeable change when checking for an improvement on http://www.speedtest.net/ over wireless.    I resolved the situation.  Here are some suggestions if you find yourself in a similar position:

• The ISP may have told you to reboot your router to synchronize your router to the new data rate.  Make sure to also reboot your cable modem when you do this.
• Will your speed be jumping to greater than 100 Mbps?    If so, does the WAN, also called internet connection, capable of connecting at the next highest data rate of 1 Gbps?   (In my case I had to go out and buy a new wireless router.)   
• Even if your current wireless route is capable of the higher data rate, the question is what data rate did your router actually negotiate?  To check this you need to log into your router to find out.
• How fast is your wireless data rate compared to your ISP data rate?  If you are running a speed test over wireless at home, it is important to know that what you are really measuring is throughput rate that is about 1/2 of the date rate.   Because network traffic going over the air is a shared delivery is not guaranteed.  Because of this there is a lot of overhead on wireless network to check that the bits were correctly delivered and to resend them as needed.  
• What does this mean in concrete terms?    If your data rate is 120 Mbps, you need to have a wireless router capable of at least 240 Mbps.   You would need a wireless router able to use the 802.11n or 802.11ac wireless standards.  https://en.wikipedia.org/wiki/IEEE_802.11  In my case I bought a 802.11ac router with a 1 Gbps WAN connection to make make sure the capabilities of the home device would not be a problem for a while.  If you were to go with an 802.11n device in this situation, double check the 802.11n settings as not all the settings allow you to communicate greater than 240 Mbps over wireless.