On the Performance of Device-to-Device Communications With Delay Constraint.

Device-to-device (D2D) communication permits direct communication between devices, thereby it provides performance gain for traditional cellular networks. In this paper, we investigate how to improve the performance of D2D communication while satisfying the delay constraint for practical applications. Closed-form expressions are derived for trade-offs among system performance, such as successful transmission probability, transmission capacity, delay constraint, and energy consumption. In addition, two schemes are proposed to improve the performance for D2D communication under a given delay constraint. First, an optimal transmission scheme is proposed in which the transmission of user equipment (UE) can be scheduled adaptively to have the best successful transmission probability, whereas the D2D link satisfies the delay constraint. Second, a delay assignment scheme is proposed in which delay is adaptively assigned for each hop to achieve the maximum capacity when the network employs multihop D2D communication. Simulation results show that the adaptive transmission scheme improves the successful transmission probability (e.g., increased by 13 times when the source density is \text10^-4) compared with the fixed-probability transmission scheme, although it can satisfy the delay constraints for different applications. Furthermore, compared with the fixed delay assignment scheme, the network capacity can be improved up to 50% by the proposed scheme with proper delay assignment for each hop. [ABSTRACT FROM AUTHOR]