Parallel interference cancellation device for multi-user CDMA systems
AssigneeTexas Instruments Incorporated
InventorsSundararajan Sriram, Alan Gatherer
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Abstract
This invention provide parallel interference cancellation for wireless communication base stations. Received user inputs symbols are spread by means of pseudo-noise sequences to form user input chip vectors. These are added together and interpreted to form chip vectors of interference samples. These chip vectores are despread to form interference output symbols by means of said pseudo-noise sequences. The interference output signals are subtracted from the received user input symbols to obtain a first estimate of transmitted symbols. This process may be continued for two or more iterations to obtain better interference cancellation.
Claims9
A method for cancellation of interference in wireless communication comprising the steps of:
- spreading received user input symbols by means of pseudo-noise sequences to form user input chip vectors;
- adding together and interpreting said user input chip vectors to form chip vectors of interference samples;
- despreading said chip vectors of interference samples to form interference output symbols by means of said pseudo-noise sequences;
- and
- subtracting said interference output symbols from said received user input symbols to obtain a first estimate of transmitted symbols.
A wireless CDMA base station apparatus comprising:
- a radio frequency receiver collecting and processing input radio frequency signals and converting them into digital signal serial streams of chip vectors;
- a first despreader unit receiving chip vectors from said radio frequency receiver to obtain a first estimate of input symbol vectors;
- a respreader unit receiving input intermediate chip vectors and respreading said input intermediate symbol vectors;
- a second despreader unit receiving respread intermediate symbol vectors from said respreader and dispreading them;
- and
- a digital signal processor connected to said first despreader, said second despreader and said respreader, digital signal processor programmed to:
- receive input symbol vectors from said firs. despreader and form digital signal serial streams and form first stage symbol decisions from output of first despreader unit;
- supply said first stage symbol decisions to said respreader;
- receive output of said second despreader and form next stage symbol decisions.
Dependencies are inferred from the claim text.