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IET Communications
Research Article
Performance analysis of sub-optimal transmit
and receive antenna selection amplify and
forward cooperative communication
ISSN 1751-8628
Received on 2nd January 2019
Revised 19th August 2019
Accepted on 27th September 2019
E-First on 19th November 2019
doi: 10.1049/iet-com.2018.6234
www.ietdl.org
Mokhtar Bouteggui1, Fatiha Merazka1
1LISIC Lab., Department of Telecommunications, Electronic and Computer Engineering Faculty, USTHB University, 16111, Algiers, Algeria
E-mail: fmerazka@usthb.dz
Abstract: In this study, the authors consider a multiple-input–multiple-output cooperative communication system, based on a
single amplify-and-forward relay over a Rayleigh fading channel. They investigate the performance of two sub-optimal transmit
receive antenna selection (TRAS) schemes employing M-ary phase shift keying (M-PSK). They take the advantages of the
moment generating function expression, to avoid the hypergeometric functions commonly used in literature. They derive
analytical expressions for the symbol error rate (SER) based on two upper bounds of the instantaneous end-to-end signal-to-
noise ratio (SNR), which are tightly lower bounded for the SER. In addition, an SER upper bound is derived for both TRAS
strategies which gets tighter at high SNR. This upper bound is used to determine the system optimal power allocation. Diversity
orders for both TRAS strategies are extracted. Their theoretical analysis shows that the SNR upper bound I is tighter compared
to the SNR upper bound II especially for sub-optimal strategy I. At high SNR, the derived SER upper bound approaches the
derived SER. Interestingly, it is observed that the optimal power factors lead to a lower SER. Simulation results are presented in
comparison with the derived SER for the two upper bounds.
1 Introduction
Recently, cooperative communication has been proven to be an
effective technique to provide reliable transmission over wireless
communication networks, such as cellular and wireless ad hoc
networks. In this mode of communication, one or more relays are
used between the source and the destination to form a virtual array
of transmitter antennas, to enhance the signal quality at the
destination [1].
The use of relays is based on relaying protocols such as, the
fixed-decode-and-forward (FDF), selective DF (SDF) and amplify-
and-forward (AF) protocols. In FDF protocol, the relay decodes
and forwards the received signal from the source. However, FDF
leads to diversity loss and performance degradation due to
erroneous relaying detection at relay [2]. SDF protocol is another
variation of the FDF protocol that can be used to avoid the
diversity loss in FDF. In SDF protocol, the relay forwards the
signal only when it decodes it correctly [3, 4]. In an AF protocol,
the relay simply amplifies the received signal and forwards it to
destination [5, 6]. Furthermore, the application of multiple-input–
multiple-output (MIMO) techniques to cooperative networks
enhances the data rate and network reliability [7] while increasing
network complexity due to the multiple radio-frequency (RF)
chains as well as the overall cost in terms of size and power [8].
One attractive way to mitigate this requirement without degrading
the performance is to use antenna selection (AS) technique, which
is a sub-optimal form of beamforming [9–11]. Note that using AS,
we can achieve full diversity order (DO), provide better
performance and reduce the system complexity.
For cooperative communication, it is important for relay nodes
to be as simple as possible while retaining acceptable performance.
Using FDF protocol, the relay needs to decode the received symbol
first, re-modulates and then forwards it to the destination. This
operation increases the complexity of FDF relay and becomes
nearly complex as a base station. On the other hand, SDF protocol
requires hardware for cyclic-redundancy-check (CRC) codes. This
leads to additional time to decode and re-encode using CRC codes
[12]. Furthermore, for some real-time services applications and
networks that are equipped with small and simple hardware, SDF
protocol may not be a good choice. Using the AF protocol, the
relay simply amplifies the received signal then forwards to the
destination without decoding. Compared to DF protocol, the
complexity of AF protocol is less [11, 13]. The focus of our work
is on AF cooperative communication system where all nodes are
equipped with multiple antennas.
Note that the authors in [2, 14] propose an ML decoder at the
destination to reduce the complexity for a based decode and
forward cooperative network with single antenna in [2] and space
time block coding in [14]. According to the results of the proposed
decoders in [2, 14], the proposed decoders can achieve maximum
possible diversity of the cooperative system studied.
For MIMO-based AF relay using AS, there are some studies
that considered the direct link between source and relay and other
works did not consider the direct link. In addition, some works
considered that all nodes are equipped with multiple antennas
whereas other works considered that not all nodes are equipped
with multiple antennas.
Starting with works that take into account the direct link with
single relay, in [10, 15], the authors considered a single relay
MIMO cooperative communication system (all nodes are equipped
with multiple antennas). The optimal strategy (Opt) that uses
transmit AS (TAS) with maximal ratio combination (MRC) at
receivers (TAS/MRC) is proposed, which achieves a full DO, by
selecting the best antenna at source and relay to maximise the end-
to-end (e2e) signal-to-noise ratio (SNR). The aforementioned
strategy has high search complexity which requires channel state
information of all the three channels as well as the intractability of
the e2e SNR analysis. Therefore, in [15], two sub-optimal low-
complexity AS strategies were proposed to reduce the complexity
of an optimal strategy, by maximising the individual channel SNRs
rather than the e2e one. The first sub-optimal strategy I denoted by
Sub-OI, maximises the SNR of source-destination and relay-
destination links, whereas the second sub-optimal strategy II
denoted by Sub-OII maximises that of the source-relay and relay-
destination links. However, in [15], the authors utilised the Monte
Carlo simulation to study the performance of the optimal strategy
as well as the two sub-optimal strategies.
In [16], the authors investigated the performance of the above
strategies (the optimal and the two sub-optimal strategies), over
Rayleigh fading channels, where only the source is equipped with
multiple antennas (the relay and the destination are limited to a
single antenna). In [17], the authors considered the case where all
IET Commun., 2019, Vol. 13 Iss. 20, pp. 3537-3546
© The Institution of Engineering and Technology 2019
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