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Frequency 8.1 Introduction / Classification Estimation of Frequency Control Systems In this chapter we are concerned with frequency estimation. We could have studied this problem earlier in Chapter 5 by including an additional parameter Q in the set 8 = (0, E, a}. The main reason why we choose to include a separate chapter is that for a sizeable frequency offset St we must first compensate this frequency offset before the other parameters (0, E, a} can be estimated. This implies that frequency offset estimation algorithms must work independently of the values of the other parameters. The operation of the algorithms is nondata. | Digital Communication Receivers Synchronization Channel Estimation and Signal Processing Heinrich Meyr Marc Moeneclaey Stefan A. Fechtel Copyright 1998 John Wiley Sons Inc. Print ISBN 0-471-50275-8 Online ISBN 0-471-20057-3 Chapter 8 Frequency Estimation 8.1 Introduction Classification of Frequency Control Systems In this chapter we are concerned with frequency estimation. We could have studied this problem earlier in Chapter 5 by including an additional parameter Q in the set 0 0 e a . The main reason why we choose to include a separate chapter is that for a sizeable frequency offset Q we must first compensate this frequency offset before the other parameters 0 e a can be estimated. This implies that frequency offset estimation algorithms must work independently of the values of the other parameters. The operation of the algorithms is nondata aided and nonclock aided. The only exception occurs for small frequency offset QT 1. In this case timing-directed algorithms are possible. This chapter is organized as follows. We first discuss in Section 8.1.1 the channel model modifications necessary to include the estimation of Q. In Section 8.2 we derive estimators which work independently of the other parameters 0 a . In a familiar way we obtain feedback algorithms by differentiating the likelihood function with respect to the parameter Q Section 8.3 . The algorithms of the first two sections operate on samples rf kTs which are sufficient statistics. If the frequency offset is restricted to small values roughly QT 0.15 timing can be recovered prior to frequency compensation. Given the timing frequency estimators are developed which work at symbol rate 1 T. These algorithms have superior tracking performance compared to the algorithms operating with samples r fcTs . Direct frequency estimators are discussed in Section 8.4. The corresponding error-feedback algorithms are studied in Section 8.5. In Section 8.6 frequency estimation for MSK signals is studied. In summary the
