Abstract
We consider the decoding of wireless communication systems with both source coding in the application layer and channel coding in the physical layer for high-performance transmission over fading channels. Variable length error correcting codes (VLECs) and space time trellis codes (STTCs) are used to provide bandwidth efficient data compression as well as coding and diversity gains. At the receiver, an iterative joint source and space time decoding scheme are developed to utilize redundancy in both STTC and VLEC to improve overall decoding performance. Issues such as the inseparable systematic information in the symbol level, the asymmetric trellis structure of VLEC, and information exchange between bit and symbol domains have been considered in the maximum a posteriori probability (MAP) decoding algorithm. Simulation results indicate that the developed joint decoding scheme achieves a significant decoding gain over the separate decoding in fading channels, whether or not the channel information is perfectly known at the receiver. Furthermore, how rate allocation between STTC and VLEC affects the performance of the joint source and space-time decoder is investigated. Different systems with a fixed overall information rate are studied. It is shown that for a system with more redundancy dedicated to the source code and a higher order modulation of STTC, the joint decoding yields better performance, though with increased complexity.
Highlights
Providing multimedia service has become an attractive application in wireless communication systems
We study the rate allocation issue dealing with how to allocate the redundancy between space time trellis codes (STTCs) and Variable length error correcting codes (VLECs) for better decoding performance under the overall bandwidth and transmission power constraint
We find that with increased decoding complexity, the joint decoding system performance can be improved by introducing more redundancy into source code while using a higher-order modulation in STTC
Summary
Providing multimedia service has become an attractive application in wireless communication systems. EURASIP Journal on Wireless Communications and Networking [7, 8] adopts iterative decoding structure and information exchange between source decoder and channel decoder It has attracted increasing attention because of its relatively low decoding complexity. Iterative detection structure is proposed in [12] for a concatenated system with reversible variable length code (RVLC), TCM, and diagonal block space time trellis code (DBSTTC). Modification of MAP decoding algorithms and information exchange between symbol and bit domains from the two component decoders are addressed This iterative decoding is evaluated in both quasi static and rapid fading channels when either perfect channel information is available or the channel estimation errors exist. We find that with increased decoding complexity, the joint decoding system performance can be improved by introducing more redundancy into source code while using a higher-order modulation in STTC.
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