LTE channel access over unlicensed bands

    公开(公告)号:US10433292B2

    公开(公告)日:2019-10-01

    申请号:US15598090

    申请日:2017-05-17

    Abstract: Methods, systems, and devices are described for wireless communications. In one method, a clear channel assessment (CCA) may be performed at a base station to determine availability of an unlicensed spectrum. A first waveform may be transmitted to a set of user equipments (UEs) over the unlicensed spectrum when available. The first waveform may indicate a first time period and a second time period during which the base station has channel access over the unlicensed spectrum. A second waveform may be received from one or more UEs responsive to the first waveform. Each second waveform may be received over the unlicensed spectrum during the first time period and may indicate that the respective UE has channel access over the unlicensed spectrum to receive data from the base station during the second time period.

    PAIRWISE CROSS CORRELATION SEQUENCES FOR NON-ORTHOGONAL MULTIPLE ACCESS WIRELESS COMMUNICATIONS

    公开(公告)号:US20190260417A1

    公开(公告)日:2019-08-22

    申请号:US16279953

    申请日:2019-02-19

    Abstract: Methods, systems, and devices for wireless communications are described that support pairwise cross correlation sequences for non-orthogonal multiple access wireless communications. A user equipment (UE) may receive, from a base station, an indication of a spreading factor and a number of transmitters in a group of non-orthogonal multiple access (NOMA) transmitters configured for concurrent transmissions. The UE may determine, based on the spreading factor and the number of transmitters, a first spreading sequence of a set of spreading sequences from a first codebook, the first spreading sequence having a defined value for pairwise cross correlation with each spreading sequence of the plurality of spreading sequences. The first UE may identify data to be transmitted in an uplink transmission, apply the first spreading sequence to the data to be transmitted in the uplink transmission, and transmit the uplink transmission to the base station.

    Reciprocal channel sounding reference signal multiplexing

    公开(公告)号:US10389503B2

    公开(公告)日:2019-08-20

    申请号:US15811289

    申请日:2017-11-13

    Abstract: Systems and techniques are disclosed to enhance the efficiency of available bandwidth between UEs and base stations. A UE transmits a sounding reference signal (SRS) to the base station. The base station characterizes the uplink channel based on the SRS received and, using reciprocity, applies the channel characterization for the downlink channel. As part of applying the channel information, the base station forms the beam to the UE based on the uplink channel information obtained from the SRS. The UE may include an array of antennas, each UE transmitting a different SRS that the base station receives and uses to characterize the downlink. Multiple UEs (or a single UE with multiple antennas) transmit SRS at the same time and frequency allocation (non-orthogonal), but with each sending its own unique SRS. Further, multiple UEs (or a single UE with multiple antennas) may send their SRS at unique time/frequency allocations (orthogonal).

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