QoS-aware Resource Allocation in Relay-enhanced TD-LTE-A Systems
Yujie Pei
1, a
, Liqiang Wang
2, b
, Xuanli Wu
1, c
1
Communication Research Center, Harbin Institute of Technology, Harbin, China
2
China Academy of Launch Vehicle Technology R&D Center, Beijing, China
a
email: peiyujie1995@163.com,
b
email: liqiangwang@163.com,
c
email: xlwu2002@hit.edu.cn
Keywords: TD-LTE-A; Relay; QoS-aware; Resource Allocation; SPRC;
Abstract. As a result of the introduction of relay technique in the Long Term Evolution Advanced
(LTE-A) system, the system performance is improved in network coverage, user (UE) fairness and
system throughput. Nevertheless, it is important to support the transmission of multimedia
application and meet various quality-of-service (QoS) requirements of different traffics. Thus, a
two-hop relay system scheduling several QoS-promising traffics is set and we propose a resource
allocation algorithm named SPRC. The superiority of the proposed resource allocation algorithm is
examined through system level simulation, compared with the two existing algorithms:
TH-MLWDF and TFQoS. The results show that PLR is lower, GBR demand is well satisfied,
fairness between R-UEs and D-UEs is guaranteed and system throughput is improved by SPRC.
Introduction
The Third Generation Partnership Project (3GPP) puts forward the relay technique to improve
system performance in relay-enhanced TD-LTE-A systems [1]. Actually, not only the performance
of system throughput and UE fairness are required to improve, but also various QoS requirements
of UEs calls for gratification. It is essential to provide more impeccable service to UEs.
In recent years, many researchers are focusing on the study of the resource allocation scheme in
wireless relay networks. The authors in [2] used a proportional fairness (PF) utility as the objective
function. However, the demand of various QoS requirements is not considered. A low-complexity
QoS-aware resource allocation algorithm aiming at maximizing system throughput is proposed in [3]
and [4], but they do not consider the effect of delay, which is an influential factor to guarantee QoS.
The authors in [5] adopt a two-stage scheduling algorithm at both the evolved NodeB (eNB) and
Relay Nodes (RNs). The higher stage scheduling considers the delay demand, while the lower one
employs the PF algorithm. However, it does not take the resource division between the eNB and
RNs into account, i.e., all UEs are R-UEs. Ref. [6] shows that QoS-relevant parameters have an
influence on the capacity in relay networks theoretically, and the simulation shows that maximum
capacity is reduced with the growth of the required data rate of UEs, while advanced with the
growth of the allowed delay. The authors in [7] propose a QoS-aware scheduling policy with the
goal of achieving balance of traffic delay and bit rate.
Aiming at solving the problems in these existing papers, this paper proposes a QoS-guaranteed
resource scheduling algorithm, which brings data rate, time delay and the service priority factors
into the scheduling priority formula in TD-LTE-A uplink system with RNs. In LTE uplink, we
should reduce the Peak to Average Power Ratio (PAPR) concerning terminal equipment cost, hence
Single-carrier Frequency-Division Multiple Access (SC-FDMA) is employed. In order to ensure the
orthogonality of the subcarriers in uplink, the subcarriers assigned to each UE must be continuous
in the frequency domain, which should be considered in the scheduling algorithm.
System Model
A. Communication Scenario in TD-LTE-A Relay System
In this paper, in-band relays are adopted, which multiplex the same frequency resources in access
and backhaul links. And the relay is time division half-duplex. What’s more, DF protocol is
4th International Conference on Electrical & Electronics Engineering and Computer Science (ICEEECS 2016)
Copyright © 2016, the Authors. Published by Atlantis Press.
This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/).
Advances in Computer Science Research, volume 50