Wireless Multimedia Transmission Through Cooperative Spectrum Sharing With Quantized Feedback

A cooperative spectrum-sharing strategy is proposed for a hierarchical multimedia network consisting of a cellular base station transmitting high-priority (HP) data to a user equipment (UE) and multiple device-to-device (D2D) connection pairs which transmit low-priority (LP) signal to offload the cellular data traffic. In implementing the proposed strategy, the precoding design at each D2D transmitter is performed in such a way as to enhance the strength of the HP signal and minimize the interference caused at the UE by the D2D transmission. Furthermore, in accordance with the quantized signal-to-noise ratio (SNR) information reported by the UE for the cellular downlink, each D2D transmitter selects the power allocation factor which maximizes the D2D transmission rate while simultaneously satisfying the outage probability constraint for the HP signal. Having chosen the precoding vectors and power allocation factor for each D2D connection, the D2D transmitter which achieves the maximum D2D transmission rate is selected in a distributed manner via opportunity carrier sensing. The effectiveness of the proposed spectrum-sharing strategy is investigated by means of computer simulations. The results confirm that for most SNR regimes, the proposed strategy successfully meets the outage constraint on the HP signal while simultaneously maximizing the achievable rate of the LP signal.