Remote terminal spread spectrum CDMA subtractive interference canceller
First Claim
1. A remote terminal spread-spectrum code division multiple access (CDMA) interference canceller for reducing interference in a received spread-spectrum CDMA signal having N channels, with each of the N channels identified by a distinct chip-code signal, comprising:
- a plurality of means for generating a plurality of chip-code signals;
a plurality of despreading means, with each of said despreading means responsive to the respective distinct chip-code signal identifying a corresponding one of the N channels, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively;
a plurality of delay means providing proper timing for the plurality of chip-code signals;
a plurality of means, responsive to the plurality of delayed chip-code signals, for simultaneously spread-spectrum processing the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal;
means, for an ith chip-code signal, for simultaneously subtracting from the spread-spectrum CDMA signal, each of N-1 spread-spectrum-processed-despread signals, with the N-1 spread-spectrum-processed-despread signals excluding a spread-spectrum processed-despread signal of the ith despread signal, thereby generating a subtracted signal; and
channel means for despreading the subtracted signal with the ith chip-code signal as an ith channel.
0 Assignments
0 Petitions
Accused Products
Abstract
A spread-spectrum code division multiple access interference canceller employed by a remote terminal for reducing interference in a direct sequence CDMA receiver having N chip-code channels. The interference canceller includes a plurality of correlators or matched filters, a plurality of spread-spectrum-processing circuits, subtracting circuits, and channel correlators or channel-matched filters. Using a plurality of chip-code signals, the correlators despread the spread-spectrum CDMA signal as despread signals, respectively. The spread-spectrum-processing circuits use a timed version of the chip-code signals, for spread-spectrum processing the despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal. For recovering a code channel using an ith chip-code-signal, the subtracting circuits subtracts from the spread-spectrum CDMA signal, each of the N-1 spread-spectrum-processed-despread signals thereby generating a subtracted signal. The N-1 spread-spectrum-processed-despread signals do not include the spread-spectrum-processed-despread signal of the ith channel. The channel correlator or channel-matched filter despreads the subtracted signal.
-
Citations
20 Claims
-
1. A remote terminal spread-spectrum code division multiple access (CDMA) interference canceller for reducing interference in a received spread-spectrum CDMA signal having N channels, with each of the N channels identified by a distinct chip-code signal, comprising:
-
a plurality of means for generating a plurality of chip-code signals; a plurality of despreading means, with each of said despreading means responsive to the respective distinct chip-code signal identifying a corresponding one of the N channels, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of delay means providing proper timing for the plurality of chip-code signals; a plurality of means, responsive to the plurality of delayed chip-code signals, for simultaneously spread-spectrum processing the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal; means, for an ith chip-code signal, for simultaneously subtracting from the spread-spectrum CDMA signal, each of N-1 spread-spectrum-processed-despread signals, with the N-1 spread-spectrum-processed-despread signals excluding a spread-spectrum processed-despread signal of the ith despread signal, thereby generating a subtracted signal; and channel means for despreading the subtracted signal with the ith chip-code signal as an ith channel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
-
-
16. A remote terminal spread-spectrum code division multiple access (CDMA) interference canceller for reducing interference in a received spread-spectrum CDMA signal having N channels, with each of the N channels identified by a distinct chip-code signal, comprising:
-
a plurality of chip-code-signal generators for generating, simultaneously, a plurality of chip-code signals; a plurality of correlators, responsive to a plurality of distinct chip-code signals, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of delay devices coupled to said plurality of chip-code signal generators to provide proper timing for the plurality of chip-code signals as a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the timed plurality of chip-code signals, for simultaneously spread-spectrum processing, the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal; a subtractor, for an ith chip-code signal, for simultaneously subtracting from the spread-spectrum CDMA signal, each of the N-1 spread-spectrum-processed-despread signals, with the N-1 spread-spectrum-processed-despread signals, excluding a spread-spectrum processed despread signal of the ith despread signal, thereby generating a subtracted signal; and a channel correlator for despreading the subtracted signal with the ith chip-code signal as an ith channel.
-
-
17. A remote terminal spread-spectrum code division multiple access (CDMA) interference canceller for reducing interference in a received spread-spectrum CDMA signal having N chip-code channels, with each of the N channels identified by a distinct chip-code signal, comprising:
-
a plurality of matched filters, responsive to a plurality of distinct chip-code signals, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of chip-code-signal generators, responsive to a plurality of despread signals from the plurality of matched filters, for generating a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the plurality of despread signals from the plurality of matched filters and the timed plurality of chip-code signals from the plurality of chip-code-signal generators, respectively, for spread-spectrum processing, simultaneously, the plurality of despread signals, respectively, with a timed chip-code signal corresponding to a respective despread signal; a subtractor, for an ith chip-code signal, for subtracting from the spread-spectrum CDMA signal, simultaneously, each of the N-1 spread-spectrum-processed-despread signals, with the N-1 spread-spectrum-processed-despread signals not including a spread-spectrum processed despread signal of the ith despread signal, thereby generating a subtracted signal; and a channel matched filter for despreading the subtracted signal with the ith chip-code signal as an ith channel.
-
-
18. A remote terminal spread-spectrum code division multiple access (CDMA) interference canceller for reducing interference in a received spread-spectrum CDMA signal having N channels, with each of the N channels identified by a distinct chip-code signal, comprising:
-
a plurality of chip-code-signal generators for generating, simultaneously, a plurality of chip-code signals; a plurality of correlators, responsive to a plurality of distinct chip-code-signals, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of delay devices coupled to said plurality of chip-code signal generators to provide proper timing for the plurality of chip-code signals as a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the timed plurality of chip-code signals, for simultaneously spread-spectrum processing the plurality of despread signals, respectively, with a chip-code-signal corresponding to a respective despread signal, producing N spread-spectrum-processed-despread signals; a plurality of subtractors, each of said plurality of subtractors for subtracting from the spread-spectrum CDMA signal all but a particular one of the N spread-spectrum-processed-despread signals, with the particular one of the N spread-spectrum-processed-despread signals being different for each of said plurality of subtractors, thereby generating a plurality of subtracted signals; and a plurality of channel correlators for despreading the plurality of subtracted signals with a particular one of the plurality of chip-code signals, respectively, as a plurality of channels.
-
-
19. A remote terminal spread-spectrum code division multiple access (CDMA) interference canceller for reducing interference in a received spread-spectrum CDMA signal having N channels, with each of the N channels identified by a distinct chip-code signal, comprising:
-
a plurality of chip-code-signal generators for generating, simultaneously, a plurality of chip-code signals; a plurality of correlators, responsive to a plurality of distinct chip-code-signals, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of delay devices coupled to said plurality of chip-code-signal generators to provide proper timing for the plurality of chip-code signals as a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the timed plurality of chip-code signals, for simultaneously spread-spectrum processing the plurality of despread signals, respectively, with a chip-code signal corresponding to a respective despread signal, producing N spread-spectrum-processed-despread signals; a first subtractor, for subtracting from the spread-spectrum CDMA signal, all but a first one of the N spread-spectrum-processed-despread signals, a plurality of chip-code-signal generators, responsive to a plurality of despread signals from the plurality of matched filters, for generating, simultaneously, a timed plurality of chip-code signals, respectively; a plurality of mixers, responsive to the plurality of despread signals from the plurality of matched filters and the timed plurality of chip-code signals from the plurality of chip-code signal generators, respectively, for simultaneously spread-spectrum processing the plurality of despread signals, respectively, with a timed chip-code signal corresponding to a respective despread signal, producing N spread-spectrum-processed-despread signals; a plurality of subtractors, each of said plurality of subtractors for subtracting from the spread-spectrum CDMA signal all but a particular one of the N spread-spectrum-processed-despread signals, with the particular one of the N spread-spectrum-processed-despread signals being different for each of said plurality of subtractors, thereby generating a plurality of subtracted signals; and a plurality of channel-matched filters for despreading the plurality of subtracted signals with a particular one of the plurality of distinct chip-code signals, respectively, as a plurality of channels.
-
-
20. A remote terminal spread-spectrum code division multiple access (CDMA) interference canceller for reducing interference in a received spread-spectrum CDMA receiver signal having N channels, with each of the N channels identified by a distinct chip-code signal, comprising:
-
a plurality of matched filters, responsive to a plurality of distinct chip-code-signals, for simultaneously despreading a plurality of spread-spectrum channels of a spread-spectrum CDMA signal as a plurality of despread signals, respectively; a plurality of chip-code signal generators, responsive to a plurality of despread signals from the plurality of matched filters, for simultaneously generating a timed plurality of chip-code-signals generators, respectively; a plurality of mixers, responsive to the plurality of despread signals from the plurality of matched filters and the timed plurality of chip-code signals from the plurality of chip-code-signal generators, respectively, for simultaneously spread-spectrum processing the plurality of despread signals, respectively, with a timed chip-code signal corresponding to a respective despread signal, producing N spread-spectrum-processed-despread signals; a first subtractor, for subtracting from the spread-spectrum CDMA signal, all but a first one of the N spread-spectrum-processed-despread signals, thereby generating a first subtracted signal; a second subtractor, for subtracting from the spread-spectrum CDMA signal, all but a second one of the N spread-spectrum-processed-despread signals, thereby generating a second subtracted signal; and an nth subtractor, for subtracting from the spread-spectrum CDMA signal, all but an nth one of the N spread-spectrum-processed-despread signals, thereby generating an nth subtracted signal; a first channel-matched filter for despreading the first subtracted signal with a first chip-code signal as an estimate of a first channel; a second channel-matched filter for despreading the second subtracted signal with a second chip-code signal as an estimate of a second channel; and an nth channel-matched filter for despreading the nth subtracted signal with an nth chip-code signal as an estimate of an nth channel;
espread channels other than that channel.
-
Specification