Monday, March 20, 2017

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.  

Saturday, February 18, 2017

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?

Saturday, January 14, 2017

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.