An excess signaling technique with coding, signal superposition, and joint detection

We present a new encoded signaling concept which consists of transmitting an additional data rate of 50 % to the original data rate that is determined by the channel bandwidth, the modulation scheme, and other physical-layer functions of the transmission system. This is accomplished by overlaying an encoded version (using a rate 1/2 code with Hamming distance 4) of N/2 excess symbols to each block of N primary symbols. The resulting interference between primary and excess symbols is handled using a joint symbol detection technique with low complexity for N=8 and N=10. Our analysis shows that the transmission of the excess data rate involves an asymptotic gain in SNR of 0.8 dB as compared to conventional BPSK or QPSK signaling. Our simulation results indicate that this gain is noticeable at bit error rate (BER) values below about 10^-7