MULTI-ACCESS HYBRID OFDM-CDMA SYSTEM
First Claim
1. An apparatus for processing data for transmission over a wireless communication channel in a multiple-access OFDM-CDMA system, comprising:
- means for coding a data stream in accordance with a particular coding scheme to provide a stream of data symbols;
means for spreading the data symbol stream in a frequency domain with one or more spreading codes to provide spread data, wherein the one or more spreading codes are selected from a set of available spreading codes and assigned to the data stream;
means for transforming the spread data in accordance with a particular transformation to provide a stream of OFDM symbols;
means for scaling the stream of OFDM symbols in accordance with a particular gain selected for the data stream, wherein the particular gain is based upon an estimated signal quality;
means for covering the scaled OFDM symbols with a cover code; and
means for transmitting the covered OFDM symbols over the communication channel.
1 Assignment
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Accused Products
Abstract
In one aspect of a multiple-access OFDM-CDMA system, the data spreading is performed in the frequency domain by spreading each data stream with a respective spreading code selected from a set of available spreading codes. To support multiple access, system resources may be allocated and de-allocated to users (e.g., spreading codes may be assigned to users as needed, and transmit power may be allocated to users). Variable rate data for each user may be supported via a combination of spreading adjustment and transmit power scaling. Interference control techniques are also provided to improve system performance via power control of the downlink and/or uplink transmissions to achieve the desired level of performance while minimizing interference. A pilot may be transmitted by each transmitter unit to assist the receiver units perform acquisition, timing synchronization, carrier recovery, handoff, channel estimation, coherent data demodulation, and so on.
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Citations
22 Claims
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1. An apparatus for processing data for transmission over a wireless communication channel in a multiple-access OFDM-CDMA system, comprising:
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means for coding a data stream in accordance with a particular coding scheme to provide a stream of data symbols; means for spreading the data symbol stream in a frequency domain with one or more spreading codes to provide spread data, wherein the one or more spreading codes are selected from a set of available spreading codes and assigned to the data stream; means for transforming the spread data in accordance with a particular transformation to provide a stream of OFDM symbols; means for scaling the stream of OFDM symbols in accordance with a particular gain selected for the data stream, wherein the particular gain is based upon an estimated signal quality; means for covering the scaled OFDM symbols with a cover code; and means for transmitting the covered OFDM symbols over the communication channel. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for processing data for transmission over a wireless communication channel in a multiple-access OFDM-CDMA system, comprising:
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means for coding a data stream in accordance with a particular coding scheme to provide a stream of data symbols; means for spreading the data symbol stream in a frequency domain with one or more spreading codes to provide spread data, wherein the one or more spreading codes are selected from a set of available spreading codes and assigned to the data stream; means for transforming the spread data in accordance with an inverse Fourier transform to provide a stream of OFDM symbols; means for appending a cyclic prefix to each OFDM symbol to provide a corresponding transmission symbol; means for scaling each transmission symbol in accordance with a particular gain selected for the data stream, wherein the particular gain is based upon an estimated signal quality responsive to a power control command of a particular multiple access power control scheme; means for covering scaled transmission symbols with a cover code; and means for transmitting the covered transmission symbols over the communication channel.
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8. An apparatus for processing data for transmission over a wireless communication channel, comprising:
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means for coding a data stream to provide a stream of data symbols; means for applying one or more spreading codes to the stream of data symbols in a frequency domain to provide spread data; means for generating a stream of OFDM symbols from the spread data; means for applying a gain to the stream of OFDM symbols based upon information regarding a communication channel over which at least some of the stream of OFDM symbols are to be transmitted, wherein the information regarding a communication channel comprises an estimated signal quality of symbols transmitted over the communication channel; and means for adjusting the spreading based on a data rate of the stream of data symbols. - View Dependent Claims (9, 10, 11)
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12. A computer-program storage apparatus for processing data for transmission over a wireless communication channel in a multiple-access OFDM-CDMA system comprising a memory having one or more software modules stored thereon, the one or more software modules being executable by one or more processors and the one or more software modules comprising:
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code for coding a data stream in accordance with a particular coding scheme to provide a stream of data symbols; code for spreading the data symbol stream in a frequency domain with one or more spreading codes to provide spread data, wherein the one or more spreading codes are selected from a set of available spreading codes and assigned to the data stream; code for transforming the spread data in accordance with a particular transformation to provide a stream of OFDM symbols; code for scaling the stream of OFDM symbols in accordance with a particular gain selected for the data stream, wherein the particular gain is based upon an estimated signal quality; code for covering the scaled OFDM symbols with a cover code; and code for transmitting the covered OFDM symbols over the communication channel. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A computer-program storage apparatus for processing data for transmission over a wireless communication channel in a multiple-access OFDM-CDMA system comprising a memory having one or more software modules stored thereon, the one or more software modules being executable by one or more processors and the one or more software modules comprising:
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code for coding a data stream in accordance with a particular coding scheme to provide a stream of data symbols; code for spreading the data symbol stream in a frequency domain with one or more spreading codes to provide spread data, wherein the one or more spreading codes are selected from a set of available spreading codes and assigned to the data stream; code for transforming the spread data in accordance with an inverse Fourier transform to provide a stream of OFDM symbols; code for appending a cyclic prefix to each OFDM symbol to provide a corresponding transmission symbol; code for scaling each transmission symbol in accordance with a particular gain selected for the data stream, wherein the particular gain is based upon an estimated signal quality responsive to a power control command of a particular multiple access power control scheme; code for covering scaled transmission symbols with a cover code; and code for transmitting the covered transmission symbols over the communication channel.
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19. A computer-program storage apparatus for processing data for transmission over a wireless communication channel comprising a memory having one or more software modules stored thereon, the one or more software modules being executable by one or more processors and the one or more software modules comprising:
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code for coding a data stream to provide a stream of data symbols; code for applying one or more spreading codes to the stream of data symbols in a frequency domain to provide spread data; code for generating a stream of OFDM symbols from the spread data; code for applying a gain to the stream of OFDM symbols based upon information regarding a communication channel over which at least some of the stream of OFDM symbols are to be transmitted, wherein the information regarding a communication channel comprises an estimated signal quality of symbols transmitted over the communication channel; and code for adjusting the spreading based on a data rate of the stream of data symbols. - View Dependent Claims (20, 21, 22)
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Specification