Sub-optimal iterative receiver method and system for a high-bit-rate CDMA transmission system
First Claim
1. A method for receiving a signal transmitted on a multipath transmission channel using a spread spectrum technique with a low spreading factor, said signal being transmitted in the form of sequences of coded binary symbols comprising predefined pilot symbols and data symbols, multiplied by a spreading sequence, said method including a step of determining a channel estimate using received predefined pilot symbols, the method comprisingreconstituting the transmitted signal by means of a rake receiver using a rake receiver that utilizes the channel estimate on the basis of received signals that were transmitted over the multiple paths of the transmission channel,determining an equivalent model of the channel as seen at the output of the rake receiver as a function of the channel estimate,reducing intersymbol interference in the reconstituted transmitted signal resulting from the low spreading factor, using the channel equivalent model and a DDFSE detector based on a trellis with a reduced number of states and delivering at its output estimated values of the received coded symbols,de-interleaving the coded symbols, anddecoding the estimated values of the de-interleaved coded symbols to reconstitute the transmitted data symbols.
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Accused Products
Abstract
A reception method and receiver structure that are relatively simple, that have close to optimum performance, and that use high order modulation combined with a low spreading factor are disclosed. The method receives a signal transmittal in the form of sequences of coded binary symbols comprising both predefined pilot symbols and date symbols multiplied by a spreading sequence. The method also includes a step of determining a channel estimate using received predefined pilot symbols. A system for receiving a signal transmitted on a multipath transmission channel using a spread spectrum technique and low spreading factor is also disclosed.
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Citations
10 Claims
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1. A method for receiving a signal transmitted on a multipath transmission channel using a spread spectrum technique with a low spreading factor, said signal being transmitted in the form of sequences of coded binary symbols comprising predefined pilot symbols and data symbols, multiplied by a spreading sequence, said method including a step of determining a channel estimate using received predefined pilot symbols, the method comprising
reconstituting the transmitted signal by means of a rake receiver using a rake receiver that utilizes the channel estimate on the basis of received signals that were transmitted over the multiple paths of the transmission channel, determining an equivalent model of the channel as seen at the output of the rake receiver as a function of the channel estimate, reducing intersymbol interference in the reconstituted transmitted signal resulting from the low spreading factor, using the channel equivalent model and a DDFSE detector based on a trellis with a reduced number of states and delivering at its output estimated values of the received coded symbols, de-interleaving the coded symbols, and decoding the estimated values of the de-interleaved coded symbols to reconstitute the transmitted data symbols.
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7. A system for receiving a signal transmitted on a multipath transmission channel using a spread spectrum technique and a low spreading factor, said signal being transmitted in the form of a sequence of coded binary symbols comprising predefined pilot symbols and data symbols and multiplied by a spreading sequence, said system comprising a rake receiver for reconstituting the transmitted signal using a channel estimate on the basis of the signals received and transmitted by the multiple paths of the transmission channel and first channel estimation means for estimating the channel on the basis of the pilot symbols received, to deliver a transmission channel estimate to the rake receiver, wherein the system further comprises:
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channel modeling means for determining an equivalent model of the channel as seen at the output of the rake receiver as a function of the channel estimate, reduction means for reducing intersymbol interference between received symbols, the reducing means comprising a DDFSE detector based on a trellis with a reduced number of states, for reducing intersymbol interference between received symbols using the equivalent channel model and reconstituting estimated values of the coded symbols received, de-interleaving means for de-interleaving the estimated values of the coded symbols received, and decoding means for decoding the estimated and de-interleaved values and supplying the data symbols transmitted. - View Dependent Claims (8, 9, 10)
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Specification