Cooperative Device-to-Device Communication for Uplink Transmission in Cellular System

The rapid development of the Internet of Things has brought new challenges to cellular networks with super-dense devices and deep-fading channels. These challenges may substantially decrease the transmission efficiency and increase the device's power consumption, especially in the uplink. A pressing issue is to improve enhanced Node B's (eNB) scheduler considering a large number of users. In this paper, a semi-centralized cooperative control method is proposed for the cellular uplink transmissions, where the user equipment (UE) relays are randomly selected according to a certain density decided by the eNB. Two specific cooperative schemes based on device-to-device (D2D) communications are proposed, which are the random UE relay scheme and the one further applying network coding. The D2D interference is considered and modeled based on stochastic geometry. The proposed schemes are analyzed based on two distinct traffic models, i.e., the machine type communications traffic with the small-data feature and the full-buffer traffic. Extensive Monte Carlo simulations have been conducted for the small-data traffic and the closed-form theoretical results have been derived for the full-buffer traffic. Performance gains are achieved in various scenarios and the comparisons between two cooperative schemes are made as well. The results provide an important guideline for the eNB to determine how to select and configure cooperative D2D communication for uplink.

I. Introduction

The rapid development of the Internet of Things (IoT) has brought new challenges to cellular networks due to super-dense Machine Type Communications (MTC) devices [3] and deep fading channels [4]. Serving a large number of the MTC devices will impose a huge pressure on the scheduler of the enhanced Node B (eNB). In addition, due to the complicated deployments and channel impairments for indoor/underground devices, one single transmission may need hundreds of repetitions to meet the link budget [4], which is especially undesirable for the MTC devices with limited energy supply [3]. Also, inefficient repetitions will occupy a large portion of the cellular resources and lead to performance degradation of the whole network.