Differential bandwidth and equivalent bandwidth for overloaded multiuser communications

This paper presents the basic CDMA model with jointly optimal signature sequences and power allotment for overloaded multiuser communications. The linear minimum mean-squared-error (LMMSE) receivers are being employed. It is shown that the Welch bound equality (WBE) sequences are optimal sequences for equal SINR requirements. It is also shown that users are admissible if and only if the summation of effective bandwidths is less than the processing gain. However, the notion of the Welch bound equality sequences are extended to the continuous-time waveforms.