| 摘要 |
A method and apparatus are disclosed for detecting a pilot signal in a wireless receiver using coherent combining/noncoherent detection (CCND) techniques. Coherent combining/noncoherent detection (CCND) techniques are used to detect the pilot signal whenever the receiver is already frequency locked, or otherwise known to have a small frequency offset. Conventional noncoherent combining/noncoherent detection (NCND) techniques are utilized to initially acquire the timing of the forward channel. Once the receiver is frequency locked, coherent combining/noncoherent detection (CCND) techniques may be used to continuously detect the pilot signals. After the receiver is frequency locked, the residue frequency error is small over several consecutive correlator outputs. The correlator outputs can thus be combined coherently (since the frequency error is known to be small), and the phase dependency is then eliminated by noncoherent detection. The disclosed coherent combining/noncoherent detection (CCND) technique can be extended to the case where the accumulation length, L, is too large such that coherent combining over L correlator outputs will have significant degradation even when the frequency error is small. In this case, the L outputs can be broken into M groups each of which contain L1 outputs, such that L = ML1.
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