Analysis and Dynamic Range Enhancement of the Analog-to-Digital Interface in Multimode Radio Receivers

摘要: The rapidly developing wireless market has spawned a multitude of different standards for cellular, PCS, and data. To allow users the ability to access services conforming disparate standards, multimode handsets capable software reconfiguration are needed. These ”software radios” distinguished from their traditional counterparts by strong reliance on digital channel filtering demodulation which may be reprogrammed receive standards. In these radios, higher dynamic range is required analog portion, most notably, analog-to-digital converter (ADC). This research examines through analysis simulation performance requirements converters use in radios conformant AMPS, IS-54, GSM, IS-95 cellular Simulations reveal degradation under conditions off-channel interference, fading, nonlinearities. Included this design automatic gain control (AGC) narrowband spread spectrum systems optimize quantization noise distortion due A/D overload. Lastly, methods improving interface such as nonuniform quantization, companding, dither presented. development novel using direct-sequence pseudo-noise (DSPN) technique conjunction with an asymmetrical quantizer presented compared standard techniques. Advantages ordinary ADC’s include almost one bit improvement resolution, whitening, elimination offsets, simultaneously digitize multiple signals single quantizer. requires no synchronization easily implemented.