CDMA over QAM and other Arbitrary Energy Constellations

Welch and Sidelnikov lower bounds on the maximum nontrivial correlations of complex signal sets apply to the constrained case of uniform signal energy and have long been used as a benchmark for testing the merit of signal sets in the design of good CDMA sequence families. Welch's lower bound is generalized here to the arbitrary signal energy case and applied to CDMA over QAM modulation. The generalized lower bound is compared to the original bound and an explicit QAM-CDMA family is constructed.

Lower Bounds on the Maximum Periodic and Aperiodic Correlation of Signal Sets with Arbitrary Energy Distribution

THIS IS AN UPDATED VERSION OF THE ORIGINAL PAPER Welch and Sidelnikov have obtained lower bounds on the maximum nontrivial correlations of complex signal sets constrained to have uniform signal energy. These results have long been used as a benchmark for testing the merit of signal sets, e.g., in the design of good CDMA sequence families. The Welch lower bound is generalized here to allow for arbitrary signal energy for each member of the signal set, with a view towards considering the application of CDMA to QAM signals. The generalized lower bound is compared to the original bound and a bound on their ratio is also derived. An example of a QAM-CDMA sequence family concludes the paper.

Fair Noiseless Broadcast Source Coding

We present a noiseless source coding problem in a broadcast environment and supply a simple solution to this problem. A transmitter wishes to transmit a binary random vector # # ### # ## # ###### # # to # receivers, where receiver # is only interested in the component # # # A source encoding is a binary sequence # ### # ## # ##### which is chosen by the transmitter