On the Bandwidth Efficiency of D2D Link Adaptation Under Co-channel Interference

A bandwidth-efficient adaptation scheme for improved device-to-device (D2D) resource allocation is presented. The scheme aims to improve the bandwidth utilization by exploiting the presence of multiple D2D communication links and the randomness of propagation channels to boost the received signal-to-noise plus interference ratio (SINR) at D2D receivers. It also attempts to allocate a D2D transmitter and a spectral channel, which can guarantee the required quality of service at a D2D receiver while reducing its processing load. It is assumed that D2D receivers use tightly spaced array elements, where multipath diversity is not resolvable. However, they are exploited to steer the radiation pattern and cancel some cochannel interference sources while maximizing the gain in the direction of the desired signal. The statistics of the resulting SINR at the D2D receiver are quantified for generic fading models of the desired signal and remaining interference sources. Moreover, the statistics of pre-combined SINRs on D2D links for various fading models are quantified. Analytical results for selected performance metrics and processing load are provided. The results demonstrate the ability of the proposed scheme to achieve decentralized bandwidth-efficient D2D resource allocation, where its relatively low complexity is explained against its achieved performance.