Mobile demodulator architecture for a spread spectrum multiple access communication system
First Claim
1. An integrated circuit for demodulating multiple instances of a spread spectrum signal over which symbols are transmitted at a symbol rate, wherein said symbols are divided into chips at a chip rate that is higher than the symbol rate comprising:
- a plurality of demod front ends for demodulating the multiple instances of the spread spectrum signal at the chip rate; and
a symbol processing system for processing each demodulated instance of the spread spectrum signal at said symbol rate in a time-divided manner.
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Abstract
The present invention involves demodulating a signal in a spread spectrum multiple access system employing a pilot on the forward link. The rake receiver separates the signal processing based on the period over which the processing occurs. Symbol rate processing is performed by a single time-shared multiply-accumulate datapath that services multiple finger front ends and a searcher front end. The front ends are dedicated circuits that perform all chip rate processing, producing a data vector and asserting a flag indicating the results are ready to be serviced by the shared datapath. A datapath controller arbitrates use of the datapath between the finger front ends, the searcher front end, and combining functions, configuring the datapath to service them on a first-come, first-serve basis. The controller sequences the datapath through a fixed routine as dictated by the signal processing associated with the block being serviced.
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Citations
17 Claims
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1. An integrated circuit for demodulating multiple instances of a spread spectrum signal over which symbols are transmitted at a symbol rate, wherein said symbols are divided into chips at a chip rate that is higher than the symbol rate comprising:
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a plurality of demod front ends for demodulating the multiple instances of the spread spectrum signal at the chip rate; and a symbol processing system for processing each demodulated instance of the spread spectrum signal at said symbol rate in a time-divided manner. - View Dependent Claims (2, 3, 4, 5)
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6. A spread spectrum demodulation apparatus for use in a multiple access communication system, the apparatus comprising:
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a plurality of finger front ends, each front end receiving spread signals and performing chip rate signal processing associated with the spread spectrum demodulation apparatus; a buffer, coupled to the plurality of finger front ends, for buffering per symbol accumulated data vectors; a storage device for maintaining state information associated with symbol rate signal processing of the spread spectrum demodulation apparatus; an arithmetic datapath, coupled to the storage device and the buffer, for performing symbol rate multiply and accumulate functions associated with signal processing of the spread spectrum demodulation apparatus, the arithmetic datapath having a symbol output; and a datapath control circuit, coupled to the arithmetic datapath, for arbitrating the use of the arithmetic datapath among the plurality of finger front ends. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A method for spread spectrum demodulation in a multiple access communication system, the method comprising the steps of:
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receiving spread signals by a plurality of finger front ends; performing chip rate signal processing, associated with a spread spectrum demodulator, on the received spread signals; buffering per symbol accumulated data vectors of the received spread signals; saving state information, in a storage device, associated with symbol rate signal processing of the spread spectrum demodulator; performing symbol rate multiplying and accumulating functions associated with signal processing of the finger front ends; and arbitrating and sequencing the symbol rate multiplying and accumulating among the plurality of finger front ends. - View Dependent Claims (13, 14, 15)
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16. A radio for communicating in a multiple access communication system, the radio comprising:
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a controller for controlling the radio; a receiver for receiving a plurality of spread spectrum radio signals; and a demodulator, coupled to the controller and the receiver, for demodulating the radio signal, the demodulator comprising; a plurality of finger front ends, each front end receiving spread signals and performing chip rate signal processing associated with the spread spectrum demodulator; a buffer, coupled to the plurality of finger front ends, for buffering per symbol accumulated data vectors; a storage device for maintaining state information associated with symbol rate signal processing of the spread spectrum demodulator; an arithmetic datapath, coupled to the storage device and the buffer, for performing symbol rate multiply and accumulate functions associated with signal processing of the spread spectrum demodulator, the arithmetic datapath having a symbol output; a datapath control circuit, coupled to the arithmetic datapath, for arbitrating the use of the arithmetic datapath among the plurality of finger front ends; a searcher front end, coupled among the plurality of received spread signals and the arithmetic datapath, for calculating signal energy of the received spread signals; and a symbol combiner, coupled to the arithmetic datapath, for combining the symbol output into a demodulated symbol stream.
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17. A method for spread spectrum demodulation in a multiple access communication system, the method comprising the steps of:
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receiving spread signals by a plurality of finger front ends; performing chip rate signal processing, associated with a spread spectrum demodulator, on the received spread signals; buffering per symbol accumulated data vectors of the received spread signals; saving state information associated with symbol rate signal processing of the spread spectrum demodulator; performing symbol rate multiplying and accumulating functions associated with signal processing of the spread spectrum demodulator to provide a symbol output; arbitrating and sequencing the symbol rate multiplying and accumulating among the plurality of finger front ends; and combining the symbol output to generate a demodulated signal.
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Specification