QUALCOMM Incorporated
Listen-before-talk operation in an unlicensed downlink and licensed uplink deployment

Abstract:

Methods, systems, and devices for wireless communications are described. In systems supporting unlicensed downlink and licensed uplink communications, transmitter-based and/or receiver-based listen-before-talk may be implemented. In a transmitter-based scheme, a base station performs listen-before-talk on a downlink unlicensed band to monitor for signals from other base stations. In a first receiver-based scheme, a user equipment may send a clear to send signal on the licensed uplink channel or unlicensed downlink channel to assist a listen-before-talk operation at a serving base station. In a second receiver-based scheme, the user equipment monitors for downlink preamble transmissions from base stations other than a serving base station and reports detected preambles to the serving base station. The base station may schedule the user equipment based on the reported preambles. In some cases, the serving base station may signal other base stations to back off and reduce interference on the unlicensed downlink spectrum.