LTE and WiFi to co-exist.

August 12 2015: Wireless hunger for high speed services has surged rapidly due to the increase in multimedia content esp. video on the go and use of devices (other than mobile) that demand internet connectivity. True 4G cells even seems to be inadequate for the hotspot area in future. Small cells and Wifi offloading are some of the ways to cater the increasing indoor mobile data in those hotspot areas. Due to the limitation in speed of Wifi and finite spectrum in the cells in those areas, throughput is always limited to an extent. The discussion for the assignment of unlicensed spectrum to the later version of LTE is fierce and currently the talk of the hour in the wireless industry and research, which is termed as LTE-U (Unlicensed) or LAA LTE (License Assisted Access). It is also a part of the 3GPP Rel. 13 (under standard setting process) that is expected in 2016.

Wifi and GSM antenna located together inside a hospital in Kathmandu.

As large amount of bandwidth is available in 5 GHz ISM band, 3GPP and several other wireless stakeholders believes that LTE in unlicensed spectrum can meet the future data demands whereas there are some opponents (including WiFi alliance, Comcast, NCTA) who have serious reservation over the co-existence of LAA and WiFi in the same 5 GHz spectrum due to the interference. Listen Before Talk (LBT) mechanism or Clean channel selection algorithm has been devised to assign clean channels to LTE (due to other nearby LTE-U node and WiFi) but the opponents argue of not clearing out proper details about the sharing approaches and the collaboration with IEEE would have been more effective for proper standardization (Globally). 

Implementation scenario could be like the LA carrier aggregation of the Primary cell, established using licensed spectrum and co-located secondary cell using Unlicensed spectrum, with two options available for secondary cells: data either in downlink or both uplink and downlink.

Some even term LAA LTE as 4.5G LTE, which is the road to 5G (see my old blog on this) for the enormous data demands not only from the mobiles but also from the censors, wearable and much more things which need internet to be connected (IoT). It is known that FCC will opt for technology neutral approach for those unlicensed band to make efficient use of valuable frequency spectrum for increasing consumer demand. As different countries/region have separate regulatory requirement for ISM band, more work need to spare for the formulation of unified, global Standard and proper coordination also be sought to answer the genuine concern raised by WiFi community. After some field trials, LAA is also going to be being applied commercially right away for selected regions in previous LTE versions with the software upgrade and the compatible radio units.

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