Unequal error protection based on OFDM and its application in digital audio transmission

Orthogonal frequency division multiplexing (OFDM) can be used naturally and effectively to provide unequal error protection by properly allocating power and assigning constellation to each individual subchannel. The principle and algorithm of using power allocation is first reviewed and applied to digital audio as an example. MPEG-1 audio is transmitted through an OFDM system. It is found that OFDM with unequal error protection can achieve 4 to 6 dB of coding gain over a single-carrier system having the same bandwidth.