Enhanced trellis based vector quantization for coordinated beamforming

Trellis-based quantization is a suitable method for reporting channel state information in multi base-station or base-station-relay coordinated transmission schemes. Due to different path loss and shadowing from each transmitting station, the receiver experiences different long-term average signal powers from each transmitter. We first propose to use a tail-biting trellis to improve the performance of the vector quantization proposed in. To reduce decoding complexity, we present a trellis labeling technique where efficient encoding and decoding can be performed by traversing the trellis twice. Lastly, we introduce a mechanism for dynamically allocating quantization bits amongst different parts of the augmented channel state vector. A trellis simplification procedure that keeps the number of trellis states at each stage to four is shown to provide a satisfactory performance.