Abstract
As a low-complexity and energy-efficient multiple input multiple output (MIMO) technique, spatial modulation (SM) has received much interest recently. Combining SM with cooperative relaying, the performance of SM systems can be significantly improved. Considering joint transmit-receive-correlated Rayleigh channels, the error performance and power allocation (PA) of the amplify-and-forward (AF) relaying aided cooperative SM system are presented in this paper. Based on the moment generating function (MGF), the probability density function (PDF) of effective signal-to-noise ratio (SNR) is derived. With this PDF, a closed-form expression of the pairwise error probability (PEP) is obtained. Utilizing the obtained PEP and the union bound of bit error rate (BER), the approximate average BER expression is further derived, which will benefit the performance analysis of the system in spatially correlated channels. According to the asymptotical performance analysis at high SNR, an asymptotic BER expression is also derived. By minimizing this asymptotic BER, a suboptimal power allocation scheme is developed, and the closed-form PA coefficients are attained. Besides, the diversity order of system is also analyzed and derived for the performance evaluation. Numerical results show that our theoretical analysis is valid, and can match the corresponding simulation well. Moreover, the proposed PA scheme can achieve superior BER performance over the conventional equal PA scheme since the powers are well allocated in terms of channel information.
Highlights
Spatial modulation (SM), which conveys information through the constellation symbol and the activated transmit antenna (TA) index simultaneously, is a promising multiple input multiple output (MIMO) technology for 5G wireless communications, and can provide high data rate
The performances of spatial modulation system were investigated over correlated Rayleigh fading channels with perfect and imperfect estimation in [13] and [14] respectively, and the theoretical bit error rate (BER) were derived for performance analysis, but the cooperative relaying is not considered
We have investigated the performance of the cooperative SM system with AF relaying over joint transmit-receive correlated Rayleigh fading channels, and derived a closedform expression of average BER
Summary
Spatial modulation (SM), which conveys information through the constellation symbol and the activated transmit antenna (TA) index simultaneously, is a promising multiple input multiple output (MIMO) technology for 5G wireless communications, and can provide high data rate. In [5], the error performance of AF relaying aided cooperative SSK system was analyzed and the corresponding theoretical BER expression was derived for arbitrary number of TAs equipped at the source. The transmit antennas and receive antennas may be correlated due to insufficient spacing, and do not operate in rich scattering environment For these reasons, the performances of spatial modulation system were investigated over correlated Rayleigh fading channels with perfect and imperfect estimation in [13] and [14] respectively, and the theoretical BERs were derived for performance analysis, but the cooperative relaying is not considered. Motivated by that, considering joint spatially correlated channels, the BER performance analysis for AF relaying assisted cooperative SM (AF-CSM) system is presented in this paper, and the corresponding theoretical BER expressions are derived.
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