WIRELESS COMMUNICATIONS AND MOBILE COMPUTING
Wirel. Commun. Mob. Comput.
(2014)
Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/wcm.2528
RESEARCH ARTICLE
Opportunistic source scheduling in multi-source
two-way relay networks
Xianfu Lei
1,2
, Rose Qingyang Hu
1
*
, Lisheng Fan
2,3
and Geng Wu
4
1
Department of Electrical and Computer Engineering, Utah State University, Logan, UT, U.S.A.
2
National Mobile Communications Research Laboratory, Southeast University, Nanjing, China
3
Department of Electronic Engineering, Shantou University, Shantou, China
4
Mobile and Communications Group, Intel Corporation, Hillsboro, OR, U.S.A.
ABSTRACT
We consider a multi-source two-way relay network, in which one source A communicates with N other sources B
n
(n D 1, 2, :::, N) with the help of a single amplify-and-forward relay. We propose two opportunistic source scheduling
schemes in such a network. According to the proposed schemes, in each transmission interval, only a single out of the N
sources B
n
is selected, and this selected node acts as either transmitter or receiver depending on the channel conditions.
For both schemes, tight closed-form lower bounds of outage probability and bit error rate (BER) are derived. Asymptotic
outage probability and BER that are valid for high signal-to-noise ratio regime are also analyzed, which can provide impor-
tant insights on the impact of system parameters. The analytical results show that the full diversity order N C 1canbe
achieved by both proposed schemes. Simulation results are also presented to corroborate the analysis. Copyright © 2014
John Wiley & Sons, Ltd.
KEYWORDS
two-way relay network; opportunistic source scheduling; outage probability; bit error rate
*Correspondence
Rose Qingyang Hu, Department of Electrical and Computer Engineering, Utah State University, Logan, UT, U.S.A.
E-mail: rosehu@ieee.org
1. INTRODUCTION
Cooperative relaying has a potential to improve coverage
area, transmission reliability, as well as system capacity
required in modern wireless communication systems [1].
The concept of wireless relaying has been adopted in a
few recent standards, such as IEEE 802.11s, IEEE 802.16j,
and 3GPP LTE-advanced. Recently, two-way relaying has
received great interest because of its higher spectral effi-
ciency than that of one-way relaying [2–12]. There are two
major amplify-and-forward-based two-way relaying proto-
cols [7] including analogy networking coding (ANC) and
time-division broadcast (TDBC) that require two and three
transmission phases, respectively.
Most previous works on two-way relaying focused
mainly on the two-source networks. However, in multiuser
networks, there are often multiple source nodes that need
to exchange data with each other. For instance, a base
station in a cellular relay system needs to communicate
with multiple mobile stations via uplinks and downlinks
with the assistance of relay stations. Therefore, investi-
gating the two-way relaying in multi-source systems is of
high essence.
On the other hand, user scheduling and resource man-
agement have been widely employed to enhance the perfor-
mance of wireless communications systems [8,9,11,13,14].
Recently, a few works have studied the opportunistic
source scheduling in multi-source two-way relay sys-
tems[8,9,11]. Specifically, in [8], the system sum rate
was studied for multi-source two-way relay system based
on ANC protocol. Closed-form outage probability was
derived in [9] for the same model with mixed fading. The
direct links between the sources were not considered in
either [8] or in [9]. In [11], the authors derived the closed-
form outage probability of a TDBC-based opportunistic
source scheduling scheme in a multi-source two-way relay
system over Nakagami-m fading channels.
In this paper, we investigate two new opportunis-
tic source scheduling schemes for a multi-source two-
way relay system, where one source node A exchanges
data information with N other source nodes B
n
’s (n D
1, 2, :::, N). In each transmission interval, only a single out
of the N sources B
n
is selected, and this selected node acts
Copyright © 2014 John Wiley & Sons, Ltd.
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