Adaptive nonuniform PSK signaling in CDMA wireless communications

In a code-division multiple-access (CDMA) wireless communication system, the channel characteristics fluctuate for many reasons, including movement of the radios, changes in propagation, and variations in interference. Adaptive signaling can be used to deliver a higher rate of information during good channel conditions while ensuring that a basic level of information is received under all channel conditions. We show that adaptive signaling schemes that employ nonuniform M-ary phase-shift-key (PSK) modulation can be used to increase the throughput in CDMA wireless communication systems with time-varying channels. The signaling method we propose supports the simultaneous transmission of multiple messages with different quality-of-service requirements