Source–Channel Coding with Feedback
Andres Kwasinski, Vinay Chande · 2022
This chapter explores how a distortion metric can be incorporated into the design of a communication system for a loss tolerant source that incorporates an acknowledgment (ACK)/negative acknowledgment (NACK) feedback channel, thus allowing for the use of an automatic repeat query (ARQ) or Hybrid ARQ protocol. It explains a passive transmitter scenario, where, on receiving a NACK, the transmitter can only do a retransmission of the codeword transmitted earlier. The chapter argues that the task of designing a source–channel feedback generation rule for packet combining-based ARQ can be mapped to a classical sequential decision problem. The tree-structured quantizer is capable of coding in several stages; each stage provides a refinement of the previous stage. The chapter explains a joint source–channel coding scheme for real-time traffic that, nevertheless, uses feedback-based error control.