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Conference Paper
Space-time block codes achieving generalized optimal diversity
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- Authors
- Moon Il Lee, Seong Keun Oh, Dong Seung Kwon
- Issue Date
- 2005-09
- Citation
- Vehicular Technology Conference (VTC) 2005 (Fall), pp.2011-2015
- Publisher
- IEEE
- Language
- English
- Type
- Conference Paper
- Abstract
- We propose a generalized code structure for constructing space-time codes (STCs) that can achieve generalized optimum diversity (GOD) with minimum delay. As a GOD code, it can achieve the full diversity and a maximum coding gain for any number of transmit antennas ( Nt ) and any rate ( R ), if the rate is less than or equal to the rank of the channel matrix. As a minimum delay code, the structure requires only Nt time slots in order to achieve the full diversity. The proposed structure combines mutually exclusive R data symbols with complex weights at each transmit antenna and the same set of data symbols is repeated at every time slot in a code block, but is transmitted through different transmit antennas with different sets of complex weights. In addition, the structure does not need any restrictions to the complex weights, thus the code can be designed with the maximum degrees of freedom. The design of an optimum code would be done by finding the set of the complex weights so that the minimum absolute determinant of code word difference matrices could be maximized. The optimum code could be easily designed so that two types of constraints, that is, the power constraints and the orthogonality constraint could be satisfied. The two constraints make the channel resource fully utilized when the channel state information (CSI) is not available at the transmitter and also reduce to the unitary constraint for capacity lossless code design in the case of R = Nt . We give two STC design examples: (1) an STC with rate 2 for two transmit antennas and (2) an STC with rate 3 for three transmit antennas. We also provide some guidelines for code design. Computer simulations are performed to demonstrate the performance of the proposed designs. From simulation results, we see that the proposed code structure and code designs can achieve GOD with minimum delay.
- KSP Keywords
- Block codes, Channel State Information(CSI), Channel resource, Code design, Code structure, Coding Gain, Computer simulation(MC and MD), Degrees of freedom(DOF), Full diversity, Orthogonality constraint, Power Constraint