On the Decoding Complexity of D-TR-STBC for Single Carrier Relay-Assisted Transmissions

In this paper, we present a low complexity maximum likelihood (ML) detection based on the sphere decoder (SD) for distributed time-reversal space-time block code (D-TR-STBC) with frequency selective fading links. Unlike direct transmission, the relay-assisted transmission results in higher number of taps for the resultant end-end channel. The complexity of Viterbi algorithm (VA) grows exponentially with the channel memory and the signal modulation order. Hence makes it prohibitive for the above scenario. On the other hand, the complexity of SD is a low-degree polynomial in the block length and does not vary significantly with the channel memory and the modulation order over the signal to noise ratio (SNR) range of interest. This offers a significant computational reduction over VA specifically for relay networks that provide higher diversity. To corroborate our claims, we have shown the simulation results comparing the average complexities of SD and VA for various system settings. A further reduction in the average complexity of SD is achieved for D-TR-STBC with multiple relays and with relay selection.

[1]  Babak Hassibi,et al.  On the sphere-decoding algorithm I. Expected complexity , 2005, IEEE Transactions on Signal Processing.

[2]  Gregory W. Wornell,et al.  Distributed space-time-coded protocols for exploiting cooperative diversity in wireless networks , 2003, IEEE Trans. Inf. Theory.

[3]  Urbashi Mitra,et al.  Sphere-constrained ML detection for frequency-selective channels , 2006, IEEE Transactions on Communications.

[4]  Björn E. Ottersten,et al.  On the complexity of sphere decoding in digital communications , 2005, IEEE Transactions on Signal Processing.

[5]  Gregory W. Wornell,et al.  Cooperative diversity in wireless networks: Efficient protocols and outage behavior , 2004, IEEE Transactions on Information Theory.

[6]  Arogyaswami Paulraj,et al.  A transmit diversity scheme for channels with intersymbol interference , 2000, 2000 IEEE International Conference on Communications. ICC 2000. Global Convergence Through Communications. Conference Record.

[7]  Georgios B. Giannakis,et al.  Single-carrier space-time block-coded transmissions over frequency-selective fading channels , 2003, IEEE Trans. Inf. Theory.

[8]  Babak Hassibi,et al.  On the sphere-decoding algorithm II. Generalizations, second-order statistics, and applications to communications , 2005, IEEE Transactions on Signal Processing.

[9]  Babak Hassibi,et al.  Maximum-Likelihood Sequence Detection of Multiple Antenna Systems over Dispersive Channels via Sphere Decoding , 2002, EURASIP J. Adv. Signal Process..

[10]  Mathini Sellathurai,et al.  Distributed STBC with relay subset selection for single carrier relay-assisted transmissions , 2008, 2008 5th International Conference on Broadband Communications, Networks and Systems.