Classified VQ codebook index assignment for communication over noisy channels

In this paper, an improved index assignment procedure is proposed to reduce the channel error effect in a communication system employing classified vector quantization (CVQ). The proposed algorithm consists of two parts: inner index assignment (IIA) and cross index assignment (CIA). The IIA reduces the distortion resulting from the error in order bits, presenting the identity of each code vector in a subcodebook. The CIA modifies the indexes assigned by the IIA in such a way that the effect of the channel error occurring in class bits, indicating the class information of the code vector can be minimized. Simulation results show that the proposed algorithms enable a reliable communication over noisy channels even without employing the channel encoding.