Social comparison based relaying in device-to-device networks

Device-to-device (D2D) communications are recognized as a key component of future wireless networks which will help to improve spectral efficiency and network densification simultaneously. In order to guarantee a quality of service (QoS) to the cellular links, the transmit power of the D2D nodes needs to be restricted, which has lead to a poor link quality over D2D transmission. One viable option to improve the D2D link quality is incorporating cooperative relays into D2D networks. However most of the existing published work in relay assisted D2D networks has assumed that relay nodes cooperate spontaneously. This cannot always be guaranteed and we take this into account by considering a fundamental model on which donation-based cooperation depends. In par- ticular we model relay cooperation as a donation game based on social comparison and characterize cooperation probability in an evolutionary context. When applying this model we evaluate the outage and capacity of relay assisted D2D network using a stochastic geometric framework

Device-to-device communications: a performance analysis in the context of social comparison-based relaying

Device-to-device (D2D) communications are recognized as a key enabler of future cellular networks which will help to drive improvements in spectral efficiency and assist with the offload of network traffic. Among the transmission modes of D2D communications are single-hop and relay assisted multi-hop transmission. Relay-assisted D2D communications will be essential when there is an extended distance between the source and destination or when the transmit power of D2D user equipments (UEs) is constrained below a certain level. Although a number of works on relay-assisted D2D communications have been presented in the literature, most of those assume that relay nodes cooperate unequivocally. In reality, this cannot be assumed since there is little incentive to cooperate without a guarantee of future reciprocal behavior. Cooperation is a social behavior that depends on various factors, such as peer comparison, incentives, the cost to the donor and the benefit to the recipient. To incorporate the social behavior of D2D relay nodes, we consider the decision to relay using the donation game based on social comparison and characterize the probability of cooperation in an evolutionary context. We then apply this within a stochastic geometric framework to evaluate the outage probability and transmission capacity of relay assisted D2D communications. Through numerical evaluations, we investigate the performance gap between the ideal case of 100% cooperation and practical scenarios with a lower cooperation probability. It shows that practical scenarios achieve lower transmission capacity and higher outage probability than idealistic network views which assume full cooperation. After a sufficient number of generations, however, the cooperation probability follows the natural rules of evolution and the transmission performance of practical scenarios approach that of the full cooperation case, indicating that all D2D relay nodes adopt the same dominant cooperative strategy based on social comparison, without the need for enforcement by an external authority