Adaptive transmission in MIMO AF relay networks with orthogonal space-time block codes over Nakagami-m fading
Hoc Phan
0
Trung Q Duong
0
Hans-Jrgen Zepernick
0
Lei Shu
1
0
Blekinge Institute of Technology
, SE-371 79 Karlskrona,
Sweden
1
Graduate School of Information Science and Technology, Osaka University
, Osaka,
Japan
In this article, we apply different adaptive transmission techniques to dual-hop multiple-input multiple-output amplify-and-forward relay networks using orthogonal space-time block coding over independent Nakagami-m fading channels. The adaptive techniques investigated are optimal simultaneous power and rate (OSPR), optimal rate with constant power (ORCP), and truncated channel inversion with fixed rate (TCIFR). The expressions for the channel capacity of OSPR, ORCP, and TCIFR, and the outage probability of OSPR, and TCIFR are derived based on the characteristic function of the reciprocal of the instantaneous signal-to-noise ratio (SNR) at the destination. For sufficiently high SNR, the channel capacity of ORCP asymptotically converges to OSPR while OSPR and ORCP achieve higher channel capacity compared to TCIFR. Although TCIFR suffers from an increase in the outage probability relative to OSPR, it provides the lowest implementation complexity among the considered schemes. Along with analytical results, we further adopt Monte Carlo simulations to validate the theoretical analysis.
1. Introduction
During the last decade, multiple-input multiple-output
(MIMO) techniques have attracted great attention as a
way of improving spectral efficiency and reliability in
wireless communications. MIMO systems with
orthogonal space-time block coding (OSTBC) transmission are
considered as a means of providing full diversity gain
and linear decoding complexity [1-3]. In recent years,
the combination of MIMO systems using OSTBC
transmission with relay networks has been significantly
considered (see, e.g., [4-9] and the references therein). In
[4,5], the outage probability and symbol error rate (SER)
performance of MIMO decode-and-forward (DF) relay
networks with OSTBC transmission over Rayleigh fading
channels were investigated, respectively. In [6], the SER
of MIMO systems in which the source employs OSTBC
transmission to transmit the signal to the destination
through the help of semi-blind amplify-and-forward
(AF) relays over Rayleigh fading channels was derived.
In [7], the authors investigated the bit error rate (BER)
performance of MIMO channel state information
(CSI)assisted AF relay networks with OSTBC transmission
over Rayleigh fading channels. More recently, by taking
the direct link between source and destination into
account, the SER and outage probability of MIMO
CSIassisted AF relay cooperative networks with OSTBC
transmission over Rayleigh fading channels were
investigated [8]. Furthermore, closed-form expressions for the
outage probability and the SER of dual-hop MIMO
CSIassisted AF relay networks with OSTBC transmission
have been derived for independent and correlated
Nakagami-m fading channels in [9,10], respectively.
Although MIMO relay networks with OSTBC
transmission have received a lot of research efforts, all of the
above mentioned contributions concentrate on
cooperative communications with constant transmission rate
and power. For adaptive transmission, depending on the
link quality provided by the fading channels, the system
will adapt its transmission power, transmission rate,
coding rate/scheme, modulation scheme, or the arbitrary
combination of these techniques to the fluctuations
induced by the fading channels in order to enhance the
spectral efficiency [11-17]. In particular, a cooperative
relay network where the source employs constant
transmission power and adapts transmission rate through
Mary quadrature amplitude modulation (M-QAM) has
been studied in terms of outage probability, SER, and
spectral efficiency for Rayleigh fading channels [13]. The
combination of opportunistic incremental relaying with
adaptive modulation deployed in cooperative relay
networks was analyzed in [14]. This scheme has been
shown to guarantee a specific BER performance level
and improve both spectral efficiency and outage
probability. In [15], approximations for the channel capacity
of opportunistic cooperative multiple relay networks
over Rayleigh fading channels under optimal
simultaneous power and rate (OSPR), optimal rate with
constant power (ORCP), and truncated channel inversion
with fixed rate (TCIFR) were investigated. The upper
bounds of channel capacity for AF cooperative systems
over Rayleigh fading channels under adaptive
transmission were derived in [16]. Furthermore, the use of
different adaptive schemes in AF multi-hop relaying networks
over Nakagami-m fading environments was studied in
[17] wherein the achievable channel capacity was
evaluated by using the characteristic function (CHF) of the
reciprocal of the instantaneous SNR at the destination.
In [18], the Shannon channel capacity of the maximum
ratio combining (MRC) receiver over h- fading
channels and adaptive transmission has (...truncated)