Adaptive Bit Allocation in Rateless Coded MISO Downlink System with Limited Feedback
Rateless coding is a new type of feed-forward incremental redundancy channel coding technique which can be incorporated with MIMO technology to exploit both the diversity and coding gain with possibly reduced channel feedback. In this paper, the benefits of limited feedback beamforming and rateless coding are investigated jointly in a Multiple-Input Single-Output (MISO) downlink system. Based on weight enumerator analysis and with the goal of improving the effective channel gain, the authors propose an adaptive bit allocation scheme by taking advantage of the inherent relationship between the feedback codebook size and the number of transmitted coded bits. Given the feedback codebook size, they derive the required minimum number of coded bits for a reliable data recovery.