Error control systems for digital communication and storage
Error control systems for digital communication and storage
Wireless Communications: Principles and Practice
Wireless Communications: Principles and Practice
Blind multiuser channel estimation in asynchronous CDMA systems
IEEE Transactions on Signal Processing
Adaptation techniques in wireless packet data services
IEEE Communications Magazine
Channel quality estimation and rate adaptation for cellular mobile radio
IEEE Journal on Selected Areas in Communications
IEEE Transactions on Communications
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This paper presents a method of code rate adaptation using punctured convolutional codes for direct sequence spread spectrum communication systems over slowly fading channels. A blind channel estimation technique is used to estimate the nature of the multi-user channel at the detector (before the decoder). The path gains obtained from the channel estimation technique are used to adapt the code rates. Punctured codes derived from a specific rate 1/2 (M=4) mother code are used to provide error protection corresponding to the actual channel state. The upper and lower bounds on the bit error probability and the upper bound on the error event probability are derived for hard-decision and soft-decision decoding over Rayleigh and Rician fading channels. The throughput gains obtained using the adaptive scheme and the performances of the punctured codes are studied.