A hybrid half-duplex/full-duplex transmission scheme in relay-aided cellular networks

Hongbin Chen,Feng Zhao

doi:10.1186/s13638-016-0795-x

Abstract

In two-hop relay-aided cellular networks, both half-duplex (HD) and full-duplex (FD) transmission have been extensively studied. FD transmission can achieve twice throughput of HD transmission, but suffers from strong self-interference (SI), which may not be perfectly cancelled. In this paper, a hybrid HD/FD transmission scheme in a relay-aided cellular network is proposed, which not only utilizes the throughput advantage of FD but also weakens the negative effect of SI. The key idea is that a relay station (RS) switches between the HD and the FD modes based on the received signal-to-interference-plus-noise ratio (SINR). If the information rate of the base station (BS)-to-RS link is lower than a preset threshold, the RSs adopt the FD mode to guarantee the throughput; otherwise, the RSs adopt the HD mode to reduce the negative effect of SI. As FD transmission consumes more power than HD transmission, we try to maximize the system energy efficiency under the system spectral efficiency constraint and the transmit power constraints. It is difficult to solve this optimization problem directly, so the alternate optimization method is adopted to solve it, i.e., optimizing the transmit power of the BS and the transmit power of RSs in turn. Simulation results show that under perfect SI cancellation, the hybrid scheme can achieve higher energy efficiency than the HD mode by taking the throughput advantage of FD; while under poor SI cancellation, the hybrid scheme can greatly weaken the negative effect of SI and achieve higher energy efficiency than the FD mode.

Highlights

Modern cellular networks need to provide ubiquitous coverage and high data rates with low infrastructure deployment cost [1]
A large number of works have been done on HD relaying which focused on spectral efficiency [2]
FD relaying suffers from inherent self-interference (SI) which was considered impractical in the past, it has regained the attention of both industry [5, 6] and academia [7,8,9]

Summary

Introduction

Modern cellular networks need to provide ubiquitous coverage and high data rates with low infrastructure deployment cost [1]. H Lk is the SI channel coefficient from the transmit antenna to the receive antenna of the kth RS, β(0 ≤ β ≤ 1) is the interference cancellation factor at the RSs (obviously, β = 0 indicates that the SI is proenrfmecetnlytsc),anGce1⁄4lledH, 0Lbku2t it is impossible in is the SI channel practical envigain, which is caused by imperfect cancellation of SI, and Nk is the cochannel interference from the other RS transmissions From this expression, we find that a larger power of residual SI will result in a lower rate of the feeder link. 0≤PRk ≤PRk ; ðPÞ k 1⁄4 1; 2; ...; K ; where ηSE is the minimum spectral efficiency requirement, PB and PRk are the maximum allowed transmit powers of the BS and the RSs, respectively.

End while

Conclusions