Transmission mode selection for network-assisted device to device communication: A Levy-bandit approach

This paper studies device-to-device (D2D) communication underlaying cellular infrastructure, where each device pair is provided with two transmission modes: indirect and direct. Indirect transmission is a two-hop interference-free transmission via a base station. Despite being interference-free, this transmission type might be inefficient in communications scenarios where short-distance connections can be established. Moreover, the need for centralized resource allocation and utilizing extra hardware may lead to excessive complexity and unacceptable costs. In such scenarios, direct transmissions can utilize the proximity- and hop gains to achieve higher rates and lower end-to-end latencies. While having a potential for huge performance gains, direct D2D communications poses some fundamental challenges resulting from the absence of a devoted controller such as uncoordinated interference and unavailability of permanent direct channels. Roughly speaking, in an average sense, while indirect transmission pays safe and steady reward, direct transmission is risky, yielding a stochastic reward which might be lower than the guaranteed reward of indirect transmission, despite the proximity-and hop gains. Transmitters should therefore choose the most efficient transmission mode in the presence of limited information. This paper characterizes the reward process for each transmission mode to model the mode selection problem as a two-armed Levy-bandit game. Accordingly, the reward of the risky arm (direct mode) is considered to be a pure-jump Levy process, following compound Poisson distribution. Mathematical results from bandit and learning theories are used to solve the selection problem. Numerical results complete the paper.