Transmitter for a wireless communications system using multiple codes and multiple antennas
First Claim
1. A transmitter for a wireless communications system, comprising:
- a demultiplexer arranged to produce M groups each of N data sub-streams from data to be transmitted, where N and M are integers greater than one;
M orthogonal code spreaders each arranged to spread the N data sub-streams of a respective one of the M groups using N orthogonal code sequences; and
M signal combiners each arranged to combine the N orthogonally spread data sub-streams of a respective one of the M groups to produce a respective combined signal for transmission via a respective one of M transmit antennas;
wherein the N orthogonal code sequences used for each of the M groups comprise a respective one of M different overlapping combinations of N from Nw orthogonal code sequences, where Nw>
N, whereby at least one of the N orthogonal code sequences is used for a plurality of the M groups.
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Accused Products
Abstract
In a transmitter of a wireless communications system having M transmit antennas (10), each transmit antenna is supplied with a respective combined signal comprising a respective one of M groups each of N data sub-streams, orthogonally spread by N Walsh code sequences (W1 to WN). The N orthogonal code sequences used for each of the M groups comprise a respective one of M different combinations of N from Nw orthogonal code sequences, where Nw>N. M and N are integers greater than one. The combined signals can also include orthogonally spread pilot signals (WP) for channel estimation at a receiver. Orthogonality of the signals transmitted from the transmit antennas is increased, so that transmit signal power can be decreased and/or the receiver can have fewer than M receive antennas.
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Citations
25 Claims
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1. A transmitter for a wireless communications system, comprising:
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a demultiplexer arranged to produce M groups each of N data sub-streams from data to be transmitted, where N and M are integers greater than one; M orthogonal code spreaders each arranged to spread the N data sub-streams of a respective one of the M groups using N orthogonal code sequences; and M signal combiners each arranged to combine the N orthogonally spread data sub-streams of a respective one of the M groups to produce a respective combined signal for transmission via a respective one of M transmit antennas; wherein the N orthogonal code sequences used for each of the M groups comprise a respective one of M different overlapping combinations of N from Nw orthogonal code sequences, where Nw>
N, whereby at least one of the N orthogonal code sequences is used for a plurality of the M groups. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of increasing orthogonality of signals transmitted from M transmit antennas in a wireless communications system, comprising the steps of:
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producing signals to be transmitted from each transmit antenna by combining N data sub-streams orthogonalized by N orthogonal code sequences, M and N being integers greater than one; and selecting the N orthogonal code sequences used for each of the M transmit antennas as a respective one of M different overlapping combinations of N from Nw orthogonal code sequences, where Nw>
N, whereby at least one of the N orthogonal code sequences is used in a plurality of the M different combinations. - View Dependent Claims (18, 19, 20, 21)
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22. A transmitter for a wireless communications system, comprising:
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a demultiplexer arranged to produce at least two groups of data sub-streams, each group comprising at least two data sub-streams, from data to be transmitted; at least two orthogonal code spreaders each arranged to spread the data sub-streams of a respective one of the groups using orthogonal code sequences; and at least two signal combiners each arranged to combine the orthogonally spread data sub-streams of a respective one of the groups to produce a respective combined signal for transmission via a respective one of a plurality of transmit antennas; wherein different overlapping combinations of the same set of orthogonal code sequences are used for at least two of the groups. - View Dependent Claims (23)
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24. A method of increasing orthogonality of signals transmitted from a plurality of transmit antennas in a wireless communications system, comprising the steps of:
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producing signals to be transmitted from each transmit antenna by combining a plurality of data sub-streams which are orthogonalized by respective orthogonal code sequences; and selecting the orthogonal code sequences used for the transmit antennas as different overlapping combinations of the same set of orthogonal code sequences. - View Dependent Claims (25)
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Specification