Wi-Fi® equipment and Licensed-Assisted Access (LAA) of the Long Term Evolution (LTE) wireless standard are expected to share the same spectrum (5 GHz for example). To ensure co-existence in the same channel, LAA-LTE is expected to deploy some form of Listen-before-Talk (LBT) mechanism. Such LBT mechanisms are even required in certain regulatory domains (like the European Telecommunications Standards Institute (ETSI), for instance). The sensing mechanism required is “energy-detect” in the operating channel. For example, Wi-Fi implements Clear Channel Assessment Energy Detect (CCA-ED) to detect non Wi-Fi sources in the operating channel. This threshold typically set to −62 dBm/20 MHz.
It is generally anticipated that LAA-LTE will implement something similar to CCA-ED. However, in many deployment scenarios this will not be enough to avoid collisions between Wi-Fi and LAA-LTE. A Wi-Fi device and LTE device implementing LAA may not be able to detect each other based on energy detect thresholds, but a Wi-Fi receiver may indeed be interfered with by a LAA-LTE transmitter and vice versa. Specifically, if a Wi-Fi device and an LAA-LTE device were to transmit at the same time, there will be incidents of packet collisions.
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