A WiFi SIC receiver in the presence of LTE-LAA for indoor deployment

Kumar, Sumit; Kaltenberger, Florian; Ramirez, Alejandro; Kloiber, Bernhard
WCNC 2019, Wireless Communications and Networking Conference, 15-19 April 2019, Marrakech, Morocco

To fulfill the exponential growth of mobile
traffic demands, 3GPP has standardized the use of LTE
in the 5 GHz unlicensed band in the Release 13 dedicated
to LTE Licensed-Assisted Access (LTE-LAA). Simulations
and field trials have shown that incumbent WiFi (802.11ac)
in the 5 GHz unlicensed band will be the victim in such
co-channel deployment with LTE-LAA. Hence a concern is
being raised about fair co-existence. In this work, we investigate
the limits of Successive Interference Cancellation
(SIC) to recover the WiFi packets corrupted by LTE-LAA
in the event of a collision. For an indoor deployment, which
is the most probable battleground for WiFi and LTE-LAA,
we propose a method to perform SIC by using stored clean
channel estimates of stronger signals obtained during an
interference-free period. Our approach leverages the slow
fading channel and hence high coherence time of the indoor
channel. For an experimental proof of this phenomenon,
we simulated a scenario with interference between 20
MHz 802.11ac and 20 MHz LTE-LAA at different interframe-
intervals (IFI) of LTE-LAA frames. Our results
show that for an LTE-LAA IFI up to 2 milliseconds,
the proposed method of using stored channel estimates
to perform SIC can achieve significant transmit power
gain (TPG) compared to the conventional way of using
instantaneous channel estimates. Our method complements
the conventional approach to ensure improved WiFi Frame
Detection and Decoding while applying SIC. Moreover, our
method does not require any coordination between WiFi
and LTE-LAA transceivers and hence can be deployed
within existing infrastructure with minimal modifications.

Systèmes de Communication
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