RATELESS UNEQUAL ERROR PROTECTION CODES FOR THE ADDITIVE WHITE GAUSSIAN NOISE CHANNEL

Unequal error protection (UEP) and rateless coding are both methods used to combat channel uncertainty. With a rateless code, the code rate automatically adapts to the channel quality through the use of incremental redundancy. However, a rateless code lacks the ability to differentiate priorities and all bits suffer the same long delay in poor channel conditions. In contrast, UEP ensures reliable reception of higher priority bits and drops lower priority bits if the channel condition is poor. All bits can be decoded if the channel condition is above a design threshold. Enabling prioritization is one main advantage of UEP. While UEP is often highly desirable, it is constrained by the fixed design points for the various priority levels. That is, the minimum required signal-to-noise ratio (SNR) for each priority must be specified a priori. The multiple thresholds cannot be matched by the channel simultaneously, resulting in a loss in throughput. We create a coding scheme for the additive white Gaussian noise (AWGN) channel that has both rateless and unequal error protection advantages. We will use the abbreviation RUEP to refer to a rateless unequal error protection code. An RUEP code prioritizes the bitstream, as traditional UEP does, but by layering multiple rateless codes, the RUEP code is more efficient than a traditional UEP code.