High processing gain CDMA/TDMA system and method
First Claim
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1. A spread-spectrum time-division-multiple-access (SS-TDMA) system for communicating data, comprising:
- a remote unit having a SS-TDMA transmitter, said SS-TDMA transmitter including,a transmitter-first-in-first-out (transmitter-FIFO) memory, coupled to a data input, for storing data;
a transmitter TDMA subsystem, coupled to said transmitter-FIFO memory, for sending the data in a time slot from said transmitter-FIFO memory as TDMA data;
a demultiplexer, coupled to said transmitter TDMA subsystem and having a plurality of outputs, for demultiplexing the TDMA data into a plurality of sub-data-sequence signals, with a respective sub-data-sequence signal at a respective output of said demultiplexer;
chip-sequence means for outputting a plurality of chip-sequence signals, with each chip-sequence signal orthogonal to the other chip-sequence signals in said plurality of chip-sequence signals;
a plurality of product devices, coupled to the plurality of outputs of said demultiplexer, respectively, and to said chip-sequence means, for multiplying each of the sub-data-sequence signals by a respective chip-sequence signal, thereby generating a plurality of spread-spectrum channels;
a combiner, coupled to the plurality of product devices, for algebraically combining the plurality of spread-spectrum channels as a multichannel-spread-spectrum signal;
a header device, coupled to said combiner, for concatenating a header for chip-sequence synchronization, to the multichannel-spread-spectrum signal, thereby generating a spread-spectrum time division multiple access (SS-TDMA) signal; and
a transmitter-carrier subsystem, coupled to said header device, for transmitting on a carrier frequency the SS-TDMA signal using radio waves over a communications channel; and
a base terminal having a SS-TDMA receiver, said SS-TDMA receiver including,a translating device, coupled to the communications channel, for translating the SS-TDMA signal from the carrier frequency to a processing frequency;
a header-matched filter, coupled to said translating device and having an impulse response matched to the header, for detecting, at the processing frequency, the header in the SS-TDMA signal, and for outputting, responsive to detecting the header, a header-detection signal;
a receiver processor, coupled to said header-matched filter, responsive to the header-detection signal, for generating control and timing signals;
a plurality of data-matched filters, coupled to said translating device, with each data-matched filter having an impulse response matched to a chip-sequence signal of the plurality of chip-sequence signals, respectively, for despreading the multichannel-spread-spectrum signal embedded in the SS-TDMA signal as a plurality of received spread-spectrum channels, respectively;
a multiplexer, coupled to said plurality of data-matched filters, for multiplexing the plurality of received spread-spectrum channels as received-TDMA data;
a receiver-TDMA subsystem, coupled to said receiver processor and responsive to the control and timing signals, for selecting the received TDMA data from a particular time slot as received data; and
a receiver-FIFO memory, coupled to said receiver TDMA subsystem, for storing the received data, and for outputting the received data to a data output.
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Abstract
A system and method for W-CDMA transmissions from the base to a remote unit and spread-TDMA transmissions from the remote unit to the base. By using spread-TDMA on the reverse link, limitations inherent with the use of CDMA due to non-zero cross correlation are avoided. The resulting system provides high quality performance in both directions.
135 Citations
7 Claims
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1. A spread-spectrum time-division-multiple-access (SS-TDMA) system for communicating data, comprising:
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a remote unit having a SS-TDMA transmitter, said SS-TDMA transmitter including, a transmitter-first-in-first-out (transmitter-FIFO) memory, coupled to a data input, for storing data; a transmitter TDMA subsystem, coupled to said transmitter-FIFO memory, for sending the data in a time slot from said transmitter-FIFO memory as TDMA data; a demultiplexer, coupled to said transmitter TDMA subsystem and having a plurality of outputs, for demultiplexing the TDMA data into a plurality of sub-data-sequence signals, with a respective sub-data-sequence signal at a respective output of said demultiplexer; chip-sequence means for outputting a plurality of chip-sequence signals, with each chip-sequence signal orthogonal to the other chip-sequence signals in said plurality of chip-sequence signals; a plurality of product devices, coupled to the plurality of outputs of said demultiplexer, respectively, and to said chip-sequence means, for multiplying each of the sub-data-sequence signals by a respective chip-sequence signal, thereby generating a plurality of spread-spectrum channels; a combiner, coupled to the plurality of product devices, for algebraically combining the plurality of spread-spectrum channels as a multichannel-spread-spectrum signal; a header device, coupled to said combiner, for concatenating a header for chip-sequence synchronization, to the multichannel-spread-spectrum signal, thereby generating a spread-spectrum time division multiple access (SS-TDMA) signal; and a transmitter-carrier subsystem, coupled to said header device, for transmitting on a carrier frequency the SS-TDMA signal using radio waves over a communications channel; and a base terminal having a SS-TDMA receiver, said SS-TDMA receiver including, a translating device, coupled to the communications channel, for translating the SS-TDMA signal from the carrier frequency to a processing frequency; a header-matched filter, coupled to said translating device and having an impulse response matched to the header, for detecting, at the processing frequency, the header in the SS-TDMA signal, and for outputting, responsive to detecting the header, a header-detection signal; a receiver processor, coupled to said header-matched filter, responsive to the header-detection signal, for generating control and timing signals; a plurality of data-matched filters, coupled to said translating device, with each data-matched filter having an impulse response matched to a chip-sequence signal of the plurality of chip-sequence signals, respectively, for despreading the multichannel-spread-spectrum signal embedded in the SS-TDMA signal as a plurality of received spread-spectrum channels, respectively; a multiplexer, coupled to said plurality of data-matched filters, for multiplexing the plurality of received spread-spectrum channels as received-TDMA data; a receiver-TDMA subsystem, coupled to said receiver processor and responsive to the control and timing signals, for selecting the received TDMA data from a particular time slot as received data; and a receiver-FIFO memory, coupled to said receiver TDMA subsystem, for storing the received data, and for outputting the received data to a data output. - View Dependent Claims (2, 3)
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4. A method for communicating data between a remote unit and a base terminal using spread-spectrum comprising the steps, at the remote unit, of:
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storing data in a memory; sending the data from the memory in an assigned time slot as TDMA data; demultiplexing the TDMA data into a plurality of sub-data sequence signals; generating a plurality of chip-sequence signals; multiplying each of the plurality of sub-data sequence signals by a respective chip-sequence signal to generate a plurality of spread-spectrum channels; algebraically combining the plurality of spread-spectrum channels as a multi-channel spread-spectrum signal; concatenating a header to the multi-channel spread-specrum signal to generate a SS-TDMA-spread-spectrum signal; and transmitting the SS-TDMA-spread-spectrum signal to the base terminal. - View Dependent Claims (5, 6, 7)
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Specification