Signaling and multiple access techniques for ultra wideband 4G wireless communication systems

Due to the demanding performance requirements for fourth-generation wireless systems, several technologies have been considered for replacing third-generation wireless systems. Potential technologies for fourth-generation wireless systems are ultra wideband, orthogonal frequency-division multiplexing, and multi-input multi-output antenna systems. Ultra wideband is of particular interest for fourth-generation wireless applications that emphasize short range, high data rate, and/or low power. We focus on ultra wideband radio due to its unique advantages: high data rate, low power, and resilience to multipath fading effects. We discuss the signal characteristics, channel propagation, modulation schemes, and hardware implementation. Two major approaches to ultra wideband signaling, impulse-based and multicarrier ultra wideband, are elaborated. Furthermore, two categories of multiple access are also considered: distributed and centralized.