An Economic Aspect of Device-to-Device Assisted Offloading in Cellular Networks

Abstract

Abstract-Traffic offloading via device-to-device (D2D) communications has been proposed to alleviate the traffic burden on base stations (BSs) and to improve the spectral and energy efficiency of cellular networks. The success of D2D communications relies on the willingness of users to share contents. In this paper, we study the economic aspect of traffic offloading via content sharing among multiple devices and propose an incentive framework for D2D assisted offloading. In the proposed incentive framework, the operator improves its overall profit, defined as the network economic efficiency (ECE), by encouraging users to act as D2D transmitters (D2D-Txs) which broadcast their popular contents to nearby users. We analytically characterize D2D assisted offloading in cellular networks for two operating modes: 1) underlay mode and 2) overlay mode. We model the optimization of network ECE as a two-stage Stackelberg game, considering the densities of cellular users and D2D-Tx's, the operator's incentives and the popularity of contents. The closedform expressions of network ECE for both underlay and overlay modes of D2D communications are obtained. Numerical results show that the achievable network ECE of the proposed incentive D2D assisted offloading network can be significantly improved with respect to the conventional cellular networks where the D2D communications are disabled.

Wireless-Powered Device-to-Device-Assisted Offloading in Cellular Networks

“…In D2D-assisted offloading networks, popular contents can be shared directly among mobile devices as an economical way to alleviate the traffic burden on cellular BSs [10], [11], however, at the cost of increased power/energy consumption at D2D-Txs. In [3], [16], [17], incentive schemes were investigated to stimulate UEs to participate in D2D communications. In [12], [18], the social interactions among UEs, either in real life or in social networks, were exploited in the design of D2D communications.…”

“…Lemma 1. In the WPDO network, given the BS density λ B , the offloading radius R D of D2D-Txs, and the content popularity P con , the density of residual cellular UEs λ c U is given by [16] λ c U = e −PconπλDRD 2 λ U .…”

“…Proof: Please refer to Appendix B in [16]. Since the spatial distribution of cellular UEs follows a homogeneous PPP in plane R 2 , the probability mass function (PMF) for the number of cellular UEs N c j can be approximately given by [38]…”

“…Proposition 5. In the WPDO network, given the time allocation factor θ, the cellular UE data rate requirement R c , and the D2D offloading radius R D , the outage probability of a typical cellular UE is given by (13) and λ c U is given in (16).…”

“…where we assume that each BS is active and serves one cellular UE per channel, and the cellular UEs within the same cell are scheduled based on time-division multiple access (TDMA); P out c and P out d are the cellular and D2D outage probabilities given in (25) and 23, respectively; λ U − λ c U denotes the density of D2D UEs, while λ c U is given in (16). The APC is given by…”