Adaptive transmission in MIMO AF relay networks with orthogonal space-time block codes over Nakagami-m fading

EURASIP Journal on Wireless Communications and Networking, Jan 2012

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.

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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)


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Hoc Phan, Trung Q Duong. Adaptive transmission in MIMO AF relay networks with orthogonal space-time block codes over Nakagami-m fading, EURASIP Journal on Wireless Communications and Networking, 2012, pp. 11, Volume 2012, Issue 1, DOI: 10.1186/1687-1499-2012-11