Apparatus and method for performing a signal search in a coherent wireless communication system
First Claim
1. A multipath searcher for use in a coherent code division multiple access (CDMA) wireless communication system conveying a mobile communication signal, the multipath searcher including a plurality search paths searching at a corresponding plurality time offsets for the mobile communication signal, the multipath searcher comprising:
- a PN despreader having as input a set of in-phase (I) and quadrature (Q) components, and outputting a combined set of despread pilot and data in-phase (I) and quadrature (Q) components at a corresponding time offset;
a pilot signal Walsh code despreader having as input the combined set of despread pilot and data in-phase (I) and quadrature (Q) components, and outputting a pilot signal portion;
an energy accumulator for receiving, during a time period, the pilot signal portion, and outputting a corresponding energy metric at the corresponding time offset; and
an energy adjustment generator having as inputs, the energy metric, the combined set of pilot and data in-phase (I) and quadrature (Q) components, the pilot signal portion, and a combined signal symbol stream from a RAKE receiver, for generating a signal representative of a likelihood that the corresponding time offset corresponds to a valid time offset of the mobile communication signal.
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Accused Products
Abstract
A base station receiver assembly (400) for performing a signal search, which operates in a coherent code division multiple access (CDMA) wireless communication system conveying a mobile communication signal is disclosed. The assembly (400) includes a multipath signal searcher (200), a receiver (300), and an energy adjustment generator (490). The energy adjustment generator operates to combine an energy metric (241) from the multipath signal searcher (200) with a symbol match count (447) to yield a signal (448) for weighting inputs to a finger manager (260). The symbol match count (447) is based on a count, resulting from a comparison of a number of times an output from the multipath signal searcher (200) matched an output from the receiver (300). The symbol match count (447) is representative of a likelihood that a time offset selected by the finger manager (260) corresponds to a time offset of the mobile communication signal (107).
58 Citations
18 Claims
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1. A multipath searcher for use in a coherent code division multiple access (CDMA) wireless communication system conveying a mobile communication signal, the multipath searcher including a plurality search paths searching at a corresponding plurality time offsets for the mobile communication signal, the multipath searcher comprising:
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a PN despreader having as input a set of in-phase (I) and quadrature (Q) components, and outputting a combined set of despread pilot and data in-phase (I) and quadrature (Q) components at a corresponding time offset; a pilot signal Walsh code despreader having as input the combined set of despread pilot and data in-phase (I) and quadrature (Q) components, and outputting a pilot signal portion; an energy accumulator for receiving, during a time period, the pilot signal portion, and outputting a corresponding energy metric at the corresponding time offset; and an energy adjustment generator having as inputs, the energy metric, the combined set of pilot and data in-phase (I) and quadrature (Q) components, the pilot signal portion, and a combined signal symbol stream from a RAKE receiver, for generating a signal representative of a likelihood that the corresponding time offset corresponds to a valid time offset of the mobile communication signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An energy adjustment generator for use in a coherent code division multiple access (CDMA) wireless communication system conveying a mobile communication signal, the coherent code CDMA wirless communication system including a multipath signal searcher and a RAKE receiver for receiving a mobile communication signal, the energy adjustment generator comprising:
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a data signal Walsh code despreader for receiving a combined set of despread pilot and data in-phase (I) and quadrature (Q) components from the multipath signal searcher and outputting a data signal portion at a corresponding time offset; a data signal demodulator for receiving the data signal portion and a pilot signal portion from the multipath signal searcher, and outputting a signal stream; a first binary clipper for converting the signal steam into a first binary signal stream, the first binary signal stream comprising a first plurality of symbols representing the mobile communication signal at the corresponding time offset; a second binary clipper for converting a combined signal symbol stream, resulting from a plurality of receiver finger signal streams, into a second binary stream, the second binary signal stream comprising a second plurality of symbols representing the mobile communication signal; a comparator for comparing the first binary signal stream to the second binary signal stream to produce a value; a counter for counting a number of times the comparator yielded the value in the time period, and outputting a symbol match count, the symbol match count representative of a likelihood that the corresponding time offset corresponds to a valid time offset of the mobile communication signal, for a time period; and a function block for adding the symbol match count to an energy metric produced by the multipath signal searcher, to yield a signal representative of a likelihood that the corresponding time offset corresponds to a valid time offset of the mobile communication signal. - View Dependent Claims (13, 14, 15)
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16. A method for performing a mobile communication signal search using a multipath searcher in a coherent code division multiple access (CDMA) wireless communication system, the multipath searcher including a plurality search paths searching for the mobile communication signal at a corresponding plurality time offsets, the method comprising:
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PN despreading a set of in-phase (I) and quadrature (Q) components resulting from receiving and gain adjusting the mobile communication signal to yield a combined set of despread pilot and data in-phase (I) and quadrature (Q) components at a corresponding time offset; Walsh despreading the combined set of despread pilot and data in-phase (I) and quadrature (Q) components to yield a data signal portion; Walsh despreading the combined set of despread pilot and data in-phase (I) and quadrature (Q) components to yield a pilot signal portion; processing, over a time period, the pilot signal portion to produce a corresponding energy metric at the corresponding time offset; demodulating the data signal portion using the pilot signal portion to produce a signal stream, the signal steam comprised of symbols; converting the signal steam into a first binary signal stream by a first binary clipper; converting a combined signal symbol stream resulting from a plurality of receiver finger signal streams, into a second binary signal stream by a second binary clipper; comparing two corresponding symbols from the first binary signal stream and the second binary signal stream by a comparator, the comparator yielding a value of one when the two corresponding symbols are identical and yielding a value of zero when the two corresponding symbols are not identical; counting a number of times the comparator yielded a value of one in the time period by a counter, and outputting a symbol match count, the symbol match count representative of a likelihood that the corresponding time offset for the time period contains a significant mobile communication signal energy; adding the match symbol count to the energy metric by a function block to produce a signal representative of a likelihood that the corresponding time offset contains a significant mobile communication signal energy, the signal comprised of an adjusted energy value. - View Dependent Claims (17, 18)
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Specification