A Queued-Code Based on LDPC Block Codes

A ´queued-code´ is a novel code which allows for instantaneous rate adaptation, to match the current channel state information (CSI), assumed known to the transmitter. Previously, information theoretic codes were analyzed in the regime of large delay bounds. Numerical results had demonstrated the performance gain of these codes over fixed rate codes, in a range of situations. This paper presents queued-codes which are designed using low density parity check (LDPC) block codes. Simulation results demonstrate performance gain of these codes over fixed rate LDPC block codes. The simulation results are consistent with the numerical results obtained for the information theoretic codes, which is a satisfying result. Further, this paper argues for the use of rate adaptation within a codeword, as opposed to rate adaptation across codewords, when CSI is available at the transmitter.