Coherent combining/noncoherent detection (CCND) method and apparatus for detecting a pilot signal in a wireless communication system
First Claim
1. A method for detecting a pilot signal in a wireless receiver, said method comprising the steps of:
- frequency locking said receiver to an incoming data signal; and
detecting said pilot signal using a coherent combining technique and a noncoherent detection technique once said receiver is substantially frequency locked.
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Accused Products
Abstract
A method and apparatus are disclosed for detecting a pilot signal in a wireless receiver using coherent combining/noncoherent detection techniques. Coherent combining/noncoherent detection 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 techniques are utilized to initially acquire the timing of the forward channel. Once the receiver is frequency locked, coherent combining/noncoherent detection 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 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.
17 Citations
23 Claims
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1. A method for detecting a pilot signal in a wireless receiver, said method comprising the steps of:
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frequency locking said receiver to an incoming data signal; and
detecting said pilot signal using a coherent combining technique and a noncoherent detection technique once said receiver is substantially frequency locked. - View Dependent Claims (2, 3, 4, 5)
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6. A method for detecting a pilot signal in a wireless receiver, said method comprising the steps of:
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reducing a frequency offset between said receiver and an incoming signal to a predefined threshold; and
detecting said pilot signal using a coherent combining technique and a noncoherent detection technique while said frequency offset remains below said predefined threshold. - View Dependent Claims (7, 8, 9, 10)
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11. A method for detecting a pilot signal in a wireless receiver, said method comprising the steps of:
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detecting said pilot signal using a coherent combining technique and a noncoherent detection technique for M groups of L correlator outputs; and
noncoherently combining said M groups in order to detect said pilot signal. - View Dependent Claims (12, 13, 14)
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15. A wireless receiver comprising:
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means for locking the frequency of said receiver to an incoming data signal; and
a coherent combiner and a noncoherent detector for detecting a pilot signal once said receiver is substantially frequency locked. - View Dependent Claims (16, 17, 18, 19)
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20. A wireless receiver comprising:
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a noncoherent combiner and a noncoherent detector for locking the frequency of said receiver to an incoming data signal if said receiver is not substantially frequency locked; and
a coherent combiner and a noncoherent detector for detecting said pilot signal once said receiver is substantially frequency locked. - View Dependent Claims (21, 22, 23)
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Specification