Performance Analysis of Relay-Assisted D2D Network Offloading in Ultra-Dense Networks

Intensive users equipments (UEs) often make small base station (SBSs) work under full load so that subsequent access requests of UEs will be difficult to get real-time services in hot spots such as campus, dense office area or large business district. To solve this problem, device-to-device (D2D) offloading has been advocated in recent small cell architecture design. In this paper, we propose a relay-assisted D2D network offloading method without extra spectrum for ultra-dense small cell network. UEs who have new communication request in full load SBS are offloaded to the adjacent light load SBS by exploiting D2D receiver as a relay. We formulated the problem with three sub-problems: firstly, how to select the relay destination SBS; secondly, how to select the D2D relay UE; finally, how to allocate resources and control D2D UE transmitting power. Toward this end, a relay-assisted D2D communication network offloading algorithm is proposed to allocate channel resource and transmit power of D2D UE under the condition of satisfying the signal to interference plus noise ratio (SINR) of cellular UEs. The proposed scheme is evaluated through computer simulation and the results show that it can enable a significant increase in the number of accessible UEs of the network.