TABLE OF CONTENTS In this chapter we will present a wide variety of detection techniques to be used in the wireless digital communications area. Generally speaking, they are applicable to just about any digital communication system. These techniques will comprise both coherent detection and noncoherent detection principles. For illustrative purposes, we have chosen to provide detectors for Differential Quaternary Phase Shift Keying (DQPSK) and Minimum Shift Keying (MSK) modulation schemes. These techniques can also be extended to work for the higher order modulation schemes presented earlier in Chap. 2. Each technique will be described by mathematical terms and accompanied with block diagrams. Whenever possible, theoretical and/or simulation performance results will be provided. Lastly, a comparison of some of the present techniques will be provided and several conclusions will be drawn based on not only performance but also implementation complexity.
When a signal is transmitted it will encounter the wireless multipath channel discussed in Chap. 3. The received signal will have the following sources of degradation: sample timing offset, carrier frequency offset, and carrier phase offset. The timing offset will be taken care of by the timing recovery mechanism to be discussed in the latter chapters. The frequency offset will be taken care of by the automatic frequency control (AFC) mechanism to be discussed in later chapters as well. In this chapter we will address the phase offset degradation.
If one were to blindly attempt to recover the information from the received symbols without compensating for the...
