Impact of Antenna Correlation on a New Dual-Hop MIMO AF Relaying Model

Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2010, Article ID 956721, 14 pages doi:10.1155/2010/956721 Research Article Impact of Antenna Correlation on a New Dual-Hop MIMO AF Relaying Model Gayan Amarasuriya, Chintha Tellambura, and Masoud Ardakani Department of Electrical and Computer Engineering, University of Alberta, Edmonton, AB, Canada T6G 2V4 Correspondence should be addressed to Chintha Tellambura, Received 24 November 2009; Revised 23 March 2010; Accepted 25 April 2010 Academic Editor: Claude Oestges Copyright © 2010 Gayan Amarasuriya et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. A novel system model is proposed for the dual-hop multiple-input multiple-output amplify-andforward relay networks, and the impact of antenna correlation on the performance is studied. For a semiarbitrary correlated source-relay channel and an arbitrary correlated relay-destination channel, the complementary cumulative distribution function (CCDF) and the moment-generating function (MGF) approximations of the end-to-end signal-to-noise ratio (SNR) are derived. The outage probability, the average symbol error rate (SER), and the ergodic capacity approximations are also derived. Two special cases are treated explicitly: (1) dual-antenna relay and multiple-antenna destination and (2) uncorrelated antennas at the relay and correlated antennas at the destination. For the first case, the CCDF, the MGF and the average SER of an upper bound of the end-to-end SNR are derived in closed-form. For the second case, the CCDF, the MGF, the average SER, and the moments of SNR are derived in closed-form; as well, the high SNR approximations for the outage probability and the average SER are derived, and the diversity gain and coding gain are developed. Extensive numerical results and Monte Carlo simulation results are presented to verify the analytical results and to quantify the detrimental impact of antenna correlations on the system performance. 1. Introduction Cooperative relay networks have been the focus of a flurry of research activities and standard deployment [1–5]. The use of multiple antennas at the source, relay, and/or destination of relay networks offers significant performance gains [6–15]. Such cooperative multiple-input multiple-output (MIMO) relaying opens up the possibility of deploying diversity transmission techniques such as beamforming, maximal ratio transmission (MRT), maximal ratio combining (MRC), and transmit antenna selection (TAS) strategies [10–12, 15]. In this paper, a suboptimal yet a simple and efficient system model, which achieves a better trade-off among the hardware cost, complexity, and the performance, is proposed and analyzed for dual-hop MIMO amplify-and-forward (AF) relay networks. Prior Related Research. The prior work can be divided into two broad categories. The first category deals with multipleantenna terminals (source, relay, and destination) [6, 10–17]. The second category considers single-antenna terminals only [4, 5, 18–21]. Single-antenna AF relaying over two hops with source and destination using multiple antennas is analyzed in [10, 11, 13]. In these works, beamforming or MRT and MRC technologies are considered. The difference between [11] and [13] is that the former considers independent Rayleigh fading whereas the latter considers independent Nakagamim fading. In particular, [10] extends [13] to study the effect of antenna correlation at the source and destination. Moreover, in [12], the performance in independent Rayleigh fading is derived for a system, where the source uses TAS and the destination, MRC. References [6, 15] analyze the performance of dual-hop multibranch cooperative systems with decode-and-forward (DF) relays equipped with multiple receive antennas and a single transmit antenna. However, the source and the destination are single-antenna terminals. In [6], the performance metrics are derived by considering threshold-based MRC and threshold-based selection diversity combining at the 2 EURASIP Journal on Wireless Communications and Networking relay. Moreover, [15] extends [6] by employing distributed beamforming to achieve improved capacity gains. In [14, 16, 17], the performance of single-relay system, where the source, the relay, and the destination terminals are equipped with multiple transmit/receive antennas, is analyzed. All these works employ space time block codes. The analysis in [14] considers both DF and AF relaying strategies. In [16], the performance analysis employs random matrix theory. Reference [17] derives the exact outage probability in closed form. For the sake of completeness, we briefly mention some prior research of the second category dealing with singleantenna two-hop AF relay networks. Their performance over Rayleigh fading is analyzed in [4, 5]. The performance bounds for the multibranch case of such networks over Nakagami-m fading are derived in [18]. Reference [19] derives their performance over nonidentical Nakagami-m fading links. The performance bounds of such networks over generalized Gamma fading channels and nonidentical Weibull fading channels are derived in [20, 22]. In [21], the exact expressions and lower bounds for mixed Rayleigh and Rician fading channels are derived. Motivation. Although the dual-hop MIMO relay models in [10–12, 15] provide significant performance gains over single-antenna relaying [4, 5, 18–20], the following issues may arise in practical network deployments of such networks. In the emerging cellular dual-hop relay networks, employing multiple antennas at the mobile stations (MS) is strictly limited due to power and space constraints. However, there are no such constrains at the base stations (BS). On the other hand, the hardware cost and complexity associated with the relay should be low compared to a traditional BS. Although relaying can be performed by an MS as well, in this work, an infrastructure (fixed) relay [7] is considered. Such a relay can employ multiple antennas. In this paper, we consider a practical scenario where a single-antenna MS communicates with a multiple-antenna BS via a fixed relay equipped with multiple antennas. This particular setup is shown in Figure 1. The relay uses selection diversity combining (SDC) for signal reception and uses one transmit antenna for forwarding the amplified signal. Although several other antenna setups are possible for the relay, we focus on this setup for several reasons. First, alternatives such as MRC are more costly; if the relay employs MRC reception, a separate receiver chain is required for each receive antenna, and this requirement increases the cost and complexity. Second, a single transmit antenna at the relay keeps the cost comparable to that of a single antenna relay, which requires (...truncated)