EURASIP Journal on Wireless Communications and Networking 
Volume 2007 (2007), Article ID 97475, 7 pages
doi:10.1155/2007/97475
Research Article

A Simple Differential Modulation Scheme for Quasi-Orthogonal Space-Time Block Codes with Partial Transmit Diversity

Lingyang Song1 and Alister G. Burr2

 1UniK, University of Oslo, P.O. Box 70, Kjeller 2007, Norway
2Department of Electronics, University of York, Heslington, York YO10 5DD, UK
Received 21 August 2006; Revised 20 November 2006; Accepted 12 February 2007

Recommended by David Gesbert

Abstract

We report a simple differential modulation scheme for quasi-orthogonal space-time block codes. A new class of quasi-orthogonal coding structures that can provide partial transmit diversity is presented for various numbers of transmit antennas. Differential encoding and decoding can be simplified for differential Alamouti-like codes by grouping the signals in the transmitted matrix and decoupling the detection of data symbols, respectively. The new scheme can achieve constant amplitude of transmitted signals, and avoid signal constellation expansion; in addition it has a linear signal detector with very low complexity. Simulation results show that these partial-diversity codes can provide very useful results at low SNR for current communication systems. Extension to more than four transmit antennas is also considered.