AT4 wireless is to provide testing services to assess fair co-existence of Wi-Fi and LTE in 5GHz unlicensed spectrum (LTE-U) devices in accordance with the Wi-Fi Alliance’s Co-existence Test Plan. The testing is designed to assess whether commercially available LTE-U devices co-exist fairly with Wi-Fi in the same environment.
However, the Co-existence Test Plan is the subject of some controversy. Discussions have been ongoing between the Wi-Fi community and LTE-U community for a year now and the Test release date has been pushed back to September 2016.
According to reports by Fierce Wireless, the WifiForward coalition, which includes Comcast, Broadcom and Boingo Wireless, has welcomed the Plan, claiming it is ‘an extraordinary compromise on the part of the Wi-Fi proponents’. This is because the test plan leaves ‘half of all outdoor Wi-Fi connections vulnerable to LTE-U degradation’.
This has cut no ice with some in the LTE-U community, in particular Qualcomm, which told Fierce Wireless that: ‘The latest version of the test plan released by the Wi-Fi Alliance lacks technical merit, is fundamentally biased against LTE-U, and rejects virtually all the input Qualcomm provided for the last year, even on points that were not controversial.’
Fierce Wireless also reported that Evolve, a coalition of mobile and technology companies and association designed to promote LTE-U and LAA (License Assisted Access) – another variant of LTE in unlicensed spectrum – and which includes the likes of US carriers AT&T, Verizon and T-Mobile, called the new Plan ‘manifestly biased and not based on sound engineering’, and that the Wi-Fi Alliance had ‘buckled under political pressure of the cable lobby’.
The LTE-U debate is particular relevant in the USA. This is because LTE-U has been developed outside of the 3GPP standard body, unlike LAA. A key difference between the two is that LAA follows a protocol called ‘Listen before talk’ (LBT), which ensures that the channels are clear before sending data via LAA, safeguarding fair usage for Wi-Fi and LAA. This protocol is mandatory in the European Union and Japan, but not in the USA, where the FCC has allowed testing of LTE-U to take place.
The point of the Wi-Fi Alliance’s Co-existence Test Plan for LTE-U is therefore to find a way to enable fair usage when using 4G LTE radio communications technology in 5GHz unlicensed spectrum to avoid introducing the possibility of interference with Wi-Fi equipment operating in the same bands. This is what AT4 and another test house, Cetecom, are to test.
The Performance Test Tool from AT4 wireless will collect the most relevant key performance indicators (KPIs), such as throughput, latency (one-way delay), and jitter (latency variation). Official testing will commence once Wi-Fi Alliance releases the final Co-existence Test Plan, now due out in September.