SPECIAL SECTION ON NEW WAVEFORM DESIGN AND AIR-INTERFACE FOR FUTURE
HETEROGENEOUS NETWORK TOWARDS 5G
Received March 27, 2018, accepted April 23, 2018, date of publication May 1, 2018, date of current version June 5, 2018.
Digital Object Identifier 10.1109/ACCESS.2018.2832189
A Novel Diversity Receiver Design for
Cooperative Transmission System
JING GAO
1
, (Member, IEEE), YINGHUI ZHANG
2
, AND YANG LIU
2
1
Tianjin Key Laboratory of Wireless Mobile Communications and Power Transmission, Tianjin Normal University, Tianjin 300387, China
2
College of Electronic Information Engineering, Inner Mongolia University, Hohhot 010020, China
Corresponding author: Yinghui Zhang (zhangyinghuiimu@163.com)
This work was supported in part by the National Natural Science Foundation of China under Grant 61501325, Grant 61761033, and
Grant 61461036, and in part by the Natural Science Foundation of Inner Mongolia Autonomous Region of China under
Grant 2016MS0604.
ABSTRACT In this paper, we consider the performance of an amplify-and-forward relaying-based multiple-
input multiple-output space–time-block-coded cooperative communication system. We propose an efficient
two-stage receiver design for a relay-assisted transmission scenario over frequency-selective channels. It is
also demonstrated that the receiver is able to achieve the full diversity order of the system by incorporating
linear processing techniques. With this method, the potential spatial diversity and multipath diversity can
be obtained by using the diversity-combining technique, which frequency-selective fading channels can be
equivalently transformed. Simulation results show that the proposed scheme significantly outperforms the
minimum mean square error and ZF receivers, while maintaining nearly linear complexity.
INDEX TERMS Cooperative communication, space time block code, diversity reception, receiver design.
I. INTRODUCTION
Many new emerging applications have created an increas-
ing demand for higher data rates in wireless cellular
networks [1], [2]. The fast development of wireless com-
munication has motivated all kinds of wireless services and
applications. A key challenge for high-speed broadband
applications is the dispersive nature of frequency-selective
fading channels, which causes so-called inter-symbol-
interference (ISI), leading to inevitable performance degra-
dation. Theoretically, the most effective technique to mitigate
multipath fading in a wireless channel is diversity and trans-
mitter power control [3], [4]. In most scattering environments,
antenna diversity is an effective and, hence, a widely applied
technique for reducing the effect of multipath fading. The
classical approach is multiple-input multiple-output (MIMO)
combining or selection and switching in order to improve
the quality of the received signal [5], [6]. The advan-
tages of MIMO systems have been widely acknowledged;
to the extent that certain transmit diversity methods have
been incorporated into wireless standards. Although transmit
diversity is clearly advantageous on a cellular base station,
it may not be practical for other scenarios. Specifically, due to
size, cost, or hardware limitations, a wireless agent may not
be able to support multiple transmit antennas. Cooperative
communication allows single-antenna mobiles to reap some
of the benefits of MIMO systems [7], [8]. The basic idea
is that single-antenna mobiles in a multi-user scenario can
share their antennas in a manner that creates a virtual MIMO
system.
Space-time block coding (STBC) has been proposed as
a communication technique for wireless systems to realize
spatial diversity by introducing temporal and spatial cor-
relations into the transmitted signals from different anten-
nas [9]. In particular, STBC has been developed to provide
reliable transmission for MIMO antenna systems. Different
STBC designs produce codes with different multiplexing
and diversity gains [10]. Furthermore, distributed orthog-
onal space-time block coding (DSTBC) has been applied
to cooperative communication systems to obtain potential
spatial diversity [11], [12]. Although some current results
have been obtained, but most of these theories assume
that the channel is quasi-static and flat fading, in which
the fading paths are assumed to be independent of each
other. However, the actual channel is frequency-selective
fading. STBC is designed for flat fading channels at first,
so ISI can occur for the frequency-selective fading channels,
resulting in unavoidable performance losses. The bit error
rate of amplify-and-forward (AF) cooperative transmission
systems is particularly bad over frequency-selective fading
channels [13]. To solve this problem, an improved DSTBC
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VOLUME 6, 2018