MX9700522A

Spread spectrum interference canceler system and method.

Abstract

A spread-spectrum CDMA interference canceler for reducing interference in a DS/CDMA receiver having N chip-code channels. The interference canceler includes a plurality of correlators (54, 64, 74), a plurality of spread-spectrum-processing circuits (55, 65, 75), subtracting circuits (150), and channel correlators (146). Using a plurality of chip-code signals generated from chip codeword signal generators (52, 62, 72), the correlators (54, 64, 74) despreads the spread-spectrum CDMA signal as a plurality of despread signals. The plurality of spread-spectrum-processing circuits (55, 65, 75) uses a timed version of the plurality of chip-code signals generated from the delay devices (53, 63, 73), for spread-spectrum processing the plurality of despread signals. For recovering a code channel using an ith chip-code-signal, the subtracting circuits (150) subtracts from the spread-spectrum CDMA signal, each of the N-1 spread-spectrum-processed-despread signals thereby generating a subtracted signal. The channel-correlator (146) despreads the subtracted signal.

MX9700522A, drawing sheet 1 — Sheet 1 of 15

Term

Term ended

Expired 5 July 2015, 11.2 years ago.

22 claims: 8 independent, 14 dependent

1
REIVINDICACIONES 1. Un sistema anulador de interferencia de acceso múltiple de división de código de espectro de diseminación (CDMA) para reducir la interferencia en un receptor de CDMA de espectro de diseminación tiene canales N, con cada uno de los canales N identificados por una señal distinta de código de chip, caracterizado porque comprende:una pluralidad de anuladores de interferencia, cada uno de los anuladores de interferencia incluye, una pluralidad de medios para generar una pluralidad de señales de código de chip;una pluralidad de medios no diseminadores, con cada pluralidad de los medios no diseminadores en respuesta a la señal de código de señal distinta respectiva que identifica un canal correspondiente de los canales N, para no diseminar una señal de CDMA de espectro de diseminación como una pluralidad de señales no diseminadas;respectivamente, una pluralidad de medios para controlar el tiempo de la pluralidad de señales de código de chip, generando así una versión controlada en el tiempo de la pluralidad de señales de código de chip;una pluralidad de medios, en respuesta a la versión controlada en el tiempo de la pluralidad de señales de código de chip, para procesar por el espectro de diseminación la -4141 pluralidad de señales no diseminadas, respectivamente, con una señal de código .de chip que corresponde a una señal no diseminada respectiva;medios, para una señal de código de chip i ava , para sustraer de la señal CDMA de espectro de diseminación cada uno de la pluralidad N-l de señales no diseminadas, con la pluralidad N-l de las señales no diseminadas no incluyendo una señal no diseminada de una señal no diseminada i ava , generando así una señal sustraída;y medios de canal para no diseminar la señal sustraída con la señal de código de chip i ava como una señal de canal i ava ;y medios, acoplados a cada pluralidad de anuladores de interferencia, para combinar la salida de señal del canal iava. a partir de cada pluralidad de medios de canal, respectivamente.
2
El anulador de interferencia de CDMA de espectro de diseminación de conformidad con la reivindicación 1, caracterizado porque cada pluralidad de medios no diseminadores incluye:un filtro;un generador de código de chip para generar una señal de código de chip a partir de una palabra clave de chip respectiva;y -4242 un mezclador acoplado entre el filtro y el generador de código de chip.
3
El anulador de interferencia de CDMA de espectro 5 de diseminación de conformidad con la reivindicación 1, caracterizado porque cada pluralidad de medios no diseminadores incluye un filtro adaptado que tiene una respuesta de impulso adaptada a una palabra clave de chip. xO
4
El anulador de interferencia de CDMA .de espectro de diseminación de conformidad con la reivindicación 1, caracterizado porque los medios no diseminadores de canal incluyen:un filtro;15 un generador de código de chip para generar una señal de código de chip a partir de una palabra clave de chip correspondiendo a la señal de canal i^va. y un mezclador acoplado entre el filtro y el generador de código de chip.
5
El anulador de interferencia de CDMA de espectro de diseminación de conformidad con la reivindicación 2, caracterizado porque los medios no diseminadores de canal incluyen:25 un filtro;-4343 un generador de código de chip para generar una señal de código de chip a partir de una palabra clave de chip correspondiendo a la señal de canal i ava ;y un mezclador acoplado entre el filtro y el generador de código de chip.
6
El anulador de interferencia de CDMA de espectro ¿θ diseminación de conformidad con la reivindicación 3, caracterizado porque los medios no diseminadores de canal incluyen:un filtro;un generador de código de chip para generar una señal de código de chip a partir de una palabra clave de chip correspondiendo a la señal de canal i ava ;y un mezclador acoplado entre el filtro y el generador de código de chip.
7
El anulador de interferencia de CDMA de espectro de diseminación de conformidad con la reivindicación 3, caracterizado porque los medios no diseminadores de canal incluyen un filtro adaptado que tiene una respuesta de impulso adaptada a una palabra clave de chip que corresponde al canal i avo . -4444
8
El anulador de interferencia de CDMA de espectro de diseminación de conformidad con la reivindicación 1, caracterizado porque cada pluralidad de medios no diseminadores incluye un procesador de señal digital, con el 5 filtro adaptado digital teniendo una respuesta de impulso adaptada a una palabra clave de chip respectiva.
9
El anulador de interferencia de CDMA de espectro <. de diseminación de conformidad con la reivindicación 8, 10 caracterizado porque los medios no diseminadores de canal incluyen un filtro adaptado que tiene una respuesta de impulso adaptada a una palabra clave de chip que corresponde al canal i avo . 15
10
El anulador de interferencia de CDMA de espectro de diseminación de conformidad con la reivindicación 1, caracterizado porque los medios no diseminadores de canal incluyen un procesador de señal digital, el filtro adaptado digital teniendo una respuesta de impulso adaptada a una 20 palabra clave de chip que corresponde al canal i avo .
11
El anulador de interferencia de CDMA de espectro de diseminación de conformidad con la reivindicación 8, caracterizado porque los medios no diseminadores de canal 25 incluyen un primer dispositivo de onda acústica de superficie -4545 (SAW) que tiene una respuesta de impulso adaptada a una palabra clave de chip que corresponde al canal i avo .
12
El anulador de interferencia de CDMA de espectro de diseminación de conformidad con la reivindicación 1, caracterizado porque cada pluralidad de medios no diseminadores incluye un dispositivo de onda acústica de superficie (SAW) que tiene una respuesta de impulso adaptada a una palabra clave de chip que corresponde al canal i avo .
13
El anulador de interferencia de CDMA de espectro de diseminación de conformidad con la reivindicación 12, caracterizado porque los medios no diseminadores de canal incluyen un filtro adaptado que tiene una respuesta de impulso adaptada a una palabra clave de chip que corresponde al canal i avo .
14
El anulador de interferencia de CDMA de espectro de diseminación de conformidad con la reivindicación 12, caracterizado porque los medios no diseminadores de canal incluyen un qenerador de código de chip para generar una señal de código de chip a partir de un filtro adaptado digital que tiene una respuesta de impulso adaptada a una palabra clave de chip que corresponde al canal i avo . -464 6
15
El anulador de interferencia de CDMA de espectro de diseminación de conformidad con la reivindicación 12, caracterizado porque los medios no diseminadores de canal incluyen un dispositivo de onda acústica de superficie (SAW) que tiene una respuesta de impulso adaptada a una palabra clave de chip que corresponde al canal i avo .
16
Un sistema anulador de interferencia de acceso múltiple de división de código de espectro de diseminación (CDMA) para reducir la interferencia en un receptor de CDMA de espectro de diseminación que tiene canales N, con cada uno de los canales N identificado por una señal distinta de código de chip, caracterizado porque comprende:una pluralidad de anuladores de interferencia, cada uno de los anuladores de interferencia incluyendo, una pluralidad de generadores de señal de código de chip para generar una pluralidad de distintas señales de código de chip;una pluralidad de correlacionadores, en respuesta a la pluralidad de las distintas señales de código de chip, respectivamente, para no diseminar una señal de CDMA de espectro de diseminación como una pluralidad de señales no diseminadas;una pluralidad de dispositivos de retraso acoplados a la pluralidad de generadores de señ¿al de código de chip -4747 para retrasar la pluralidad de distintas señales de código de chip como una pluralidad de tiempo controlado de señales de código de chip, respectivamente;una pluralidad de mezcladores, en respuesta a la pluralidad controlada en el tiempo de las señales de código de chip, para procesar mediante espectro de diseminación la pluralidad de señales no diseminadas, respectivamente, con una señal de código de chip que corresponde a una señal no diseminada respectiva;·. un sustractor para una señal de código de chip i a va, para sustraer de la señal CDMA de espectro de diseminación, cada pluralidad de las señales no diseminadas procesadas por el espectro de diseminación N-l, con la pluralidad de señales no diseminadas procesadas por el espectro de diseminación N-l no incluyendo una señal no diseminada procesada por el espectro de diseminación de una señal no diseminada i ava , generando así una señal sustraída;un correlacionador de canal para no diseminar la señal sustraída con la señal de código de chip i ava como una señal de canal iava. y un combinador para combinar la salida de señal de canal i^va ca ¿ a una de la pluralidad de correlacionadores de canal, para generar un estimación promedio. -4848
17
Un sistema anulador de interferencia de acceso múltiple de división de código de espectro de diseminación (CDMA) para reducir la interferencia en un receptor de CDMA de espectro de diseminación que tiene canales N, cada uno de los canales N identificado por una señal distinta del código de chip, caracterizado porque comprende:una pluralidad de anuladores de interferencia, cada uno de los anuladores de interferencia incluyendo, una pluralidad de filtros adaptados, en respuesta a la pluralidad de distintas señales de código de chip, respectivamente, para no diseminar una señal de CDMA de espectro de diseminación como una pluralidad de señales no diseminadas;una pluralidad de generadores de señal de código de chip, en respuesta a la pluralidad de señales no diseminadas de la pluralidad de filtros adaptados, respectivamente, para generar una pluralidad de tiempo controlado de señales de código de chip;una pluralidad de mezcladores, en respuesta a la pluralidad de señales no diseminadas de la pluralidad de filtros adaptados y de la pluralidad de tiempo controlado de las señales de código de chip de la pluralidad de generadores de señal de código de chip, respectivamente, para procesar mediante espectro de diseminación la pluralidad de señales no diseminadas, respectivamente, con una señal de código de chip -4949 de tiempo controlado que corresponde a una señal no diseminada respectiva;un sustractor, para una señal de código de chip iava, para sustraer de la señal CDMA de espectro de 5 diseminación, cada una de una pluralidad de señales no diseminadas procesadas mediante espectro de diseminación N-l, la pluralidad de? señales no diseminadas procesadas mediante espectro de diseminación N-l no incluyendo una señal no • . diseminada procesada mediante espectro de diseminación de una 10 señal no diseminada i^va, generando así una señal sustraída;un filtro adaptado de canal para no diseminar la señal sustraída con la señal de código de chip i ava como una señal de canal i ava ;y medios para combinar la salida de señal de canal 15 íava a partir de cada pluralidad de filtros adaptados de canal.
18
Un método para reducir la interferencia en un receptor de acceso múltiple de división de código de espectro 20 de diseminación (CDMA) que tiene canales N, cada uno de los canales N identificado por una señal distinta de código de chip, utilizando una primera pluralidad de anuladores de interferencia, caracterizado porque comprende los pasos, dentro de cada pluralidad de anuladores de interferencia, de:-5050 a. no diseminar, simultáneamente, una pluralidad de canales de espectro de diseminación de una señal de CDMA de espectro de diseminación como una pluralidad de señales no diseminadas, respectivamente;5 b. procesar mediante espectro de diseminación, simultáneamente, utilizando una versión de tiempo controlado de una pluralidad de señales de código de chip, la pluralidad de señales no diseminadas, respectivamente, con una señal de código de chip correspondiendo a una señal no diseminada 10 respectiva;c. sustraer la señal CDMA de espectro de diseminación, cada uno de una pluralidad de señales no diseminadas, procesadas por espectro de diseminación N-l, con la pluralidad de señales no diseminadas procesadas por 15 espectro de diseminación de N-l no incluyendo una señal no diseminada procesada mediante espectro de diseminación de una señal no diseminada de iava, generando así una señal sustraída;d. no diseminar la señal sustraída con una señal de 20 código de chip i ava como una señal de canal i ava , produciendo un primer grupo de estimaciones de los canales N;e. repetir los pasos del inciso a al inciso d, utilizando una segunda pluralidad de anuladores de interferencia, produciendo un segundo grupo de estimaciones 25 de los canales N;-5151 f. repetir los pasos del inciso a al inciso d, utilizando una pluralidad M ava de anuladores de interferencia, produciendo un grupo M avo de estimaciones de los canales N;y g. combinar cada estimación del grupo M avo de estimaciones.
19
Un sistema anulador de interferencia de acceso múltiple de división de código de espectro de diseminación (CDMA) para reducir la interferencia en un receptor de CDMA de espectro de diseminación que tiene canales N, con cada uno de los canales N identificado mediante una señal distinta de código de chip, caracterizado porque comprende:una pluralidad de anuladores de interferencia, cada uno de los anuladores de interferencia incluyendo, una pluralidad de generadores de señal de código de chip para generar, simultáneamente, una pluralidad de señales de código de chip;una pluralidad de correlacionadores, en respuesta a una pluralidad de distintas señales de código de chip, para no diseminar simultáneamente una pluralidad de canales de espectro de diseminación de una señal de CDMA de espectro de diseminación como una pluralidad de señales no diseminadas, respectivamente;-52una pluralidad de dispositivos de retraso acoplados a la pluralidad de generadores de señal de código de chip para retrasar la pluralidad de señales de código de chip como una pluralidad de tiempo controlado de señales de código de chip, respectivamente;una pluralidad de mezcladores, en respuesta a la pluralidad de tiempo controlado de señales de código de chip, para procesar mediante espectro de diseminación, simultáneamente, la pluralidad de señales no diseminadas, respectivamente, con una señal de código de chip que corresponde a una señal no diseminada respectiva produciendo señales no diseminadas procesadas por espectro de diseminación N;una pluralidad de sustractores, cada uno de la pluralidad de los sustractores para sustraer de la señal CDMA de espectro de diseminación todas, pero una señal particular de las señales no diseminadas procesadas por espectro de diseminación N, la señal particular de las señales no diseminadas procesadas por espectro de diseminación N siendo diferente para cada una de la pluralidad de sustractores, generando así una pluralidad de señales sustraídas;una pluralidad de correlacionadores de canal para no diseminar la pluralidad de señales sustraídas con una señal particular de la pluralidad de señales de código de -535 3 chip, respectivamente, como una pluralidad de señales de canal;y medios para combinar cada señal de canal a partir de un anuladoi' de interferencia, respectivamente.
20
Un sistema anulador de interferencia de acceso múltiple de división de código de espectro de diseminación (CDMA) para reducir la interferencia en un receptor de CDMA de espectro de diseminación que tiene canales N, cada uno de los canales N identificado por una señal distinta de código de chip, caracterizado porque comprende:una pluralidad de anuladores de interferencia, cada uno de los anuladores de interferencia incluyendo, una pluralidad de generadores de señal de código de chip para generar, simultáneamente, una pluralidad de señales de código de chip;una pluralidad de correlacionadores, en respuesta a una pluralidad de distintas señales de código de chip, para no diseminar simultáneamente una pluralidad de canales de espectro de diseminación de una señal de CDMA de espectro de diseminación como una pluralidad de señales no diseminadas, respectivamente;una pluralidad de dispositivos de retraso acoplados a la pluralidad de generadores de señal de código de chip para retrasar la pluralidad de señales de código de chip cortto -5454 una pluralidad de tiempo controlado de las señales de código de chip, respectivamente;una pluralidad de mezcladores, en respuesta a la pluralidad de tiempo controlado de señales de código de chip, 5 para procesar mediante espectro de diseminación, simultáneamente, la pluralidad de señales no diseminadas, respectivamente, con una señal de código de chip que corresponde a una señal no diseminada respectiva, que produce „ señales no diseminadas procesadas por espectro de 10 diseminación N;un primer sustractor, para sustraer de la señal de CDMA de espectro de diseminación, todas excepto una primera señal de las señales no diseminadas procesadas por espectro de diseminación N, generando así una primera señal sustraída;15 un segundo sustractor, para sustraer de la señal de CDMA de espectro de diseminación, todas excepto una segunda señal de las señales no diseminadas procesadas por'espectro de diseminación N, generando así una segunda señal sustraída;y 20 un sustractor n avo , para sustraer de la señal de CDMA de espectro de diseminación, todas, excepto una de las señales n avas de las señales no diseminadas procesadas por espectro de diseminación N, generando así una señal sustraída n ava. -5555 un primer correlacionador de canal para no diseminar la primera señal sustraída con una primera señal de código de chip como una estimación para un primer canal;un segundo correlacionador de canal para no 5 diseminar la segunda señal sustraída con una segunda señal de código de chip como una estimación para un segundo canal;un correlacionador de canal n avo para no diseminar la señal sustraída n ava con una señal de código de chip n ava como una estimación para una señal de canal n ava ;y 10 medios par combinar las estimaciones del canal n avo a partir de la pluralidad de anuladores de interferencia.
21
Un sistema anulador de interferencia de acceso múltiple de división de código de espectro de diseminación 15 (CDMA) para reducir la interferencia en un receptor de CDMA de espectro de diseminación que tiene canales N, cada uno de los canales N identificado por una señal distinta de código de chip, caracterizado porque comprende:una pluralidad de anuladores de interferencia, cada 20 uno de los anuladores de interferencia incluye, una pluralidad de filtros adaptados, en respuesta a una pluralidad de distintas señales de código de chip, para no diseminar, simultáneamente una pluralidad de .canales de espectro de diseminación de una señal de CDMA de espectro de -5656 diseminación como una pluralidad de señales no diseminadas, respectivamente;una pluralidad de generadores de señal de código de chip, en respuesta a la pluralidad de señales no diseminadas 5 de la pluralidad de filtros adaptados, para generar simultáneamente, una pluralidad de tiempo controlado de señales de código de chip, respectivamente;una pluralidad de mezcladores, en respuesta a la pluralidad de;señales no diseminadas de la pluralidad de 10 filtros adaptados y la pluralidad de tiempo controlado de señales de código de chip de la pluralidad de generadores de señal de código de chip, respectivamente, para procesar por espectro de diseminación, simultáneamente, la pluralidad de señales no diseminadas, respectivamente, con una señal de 15 código de chip de tiempo controlado que corresponde a una señal no diseminada respectiva, produciendo señales no diseminadas procesadas por espectro de diseminación N;una pluralidad de sustractores, cada pluralidad de sustractores para sustraer de la señal de CDMA todas excepto 20 una señal particular de las señales no diseminadas procesadas por espectro de diseminación N, con la señal particular de las señales no diseminadas procesadas por espectro de diseminación N siendo diferente para cada una de la pluralidad de sustractores, generando así una pluralidad de 25 señales sustraídas;-5757 una pluralidad de filtros adaptados de canal para no diseminar la pluralidad de señales sustraídas con una señal particular de la pluralidad de distintas señales de código de chip, respectivamente, como una pluralidad de canales;y medios para combinar un canal respectivo de la pluralidad de anu]adores de interferencia para producir una estimación promedio.
22
Un sistema anulador de interferencia de acceso múltiple de división de código de espectro de diseminación (CDMA) para reducir la interferencia en un receptor de CDMA de espectro de diseminación que tiene canales N, cada uno de los canales N identificado por una señal distinta de código de chip, caracterizado porque comprende:una pluralidad de anuladores de interferencia, cada uno de los anuladores de interferencia incluye, una pluralidad de filtros adaptados, en respuesta a una pluralidad de distintas señales de código de chip, para no diseminar, simultáneamente una pluralidad de canales de espectro de diseminación de una señal de CDMA de espectro de diseminación como una pluralidad de señales no diseminadas, respectivamente;una pluralidad de generadores de señal de código de chip, en respuesta a la pluralidad de señales no diseminadas -5858 de la pluralidad de filtros adaptados, para generar simultáneamente, una pluralidad de tiempo controlado de señales de código de chip, respectivamente;una pluralidad de mezcladores, en respuesta a la 5 pluralidad de señales no diseminadas de la pluralidad de filtros adaptados y la pluralidad de tiempo controlado de señales de código de chip de la pluralidad de generadores de señal de código de chip, respectivamente, para procesar por espectro de diseminación, simultáneamente, la pluralidad de 10 señales no diseminadas, respectivamente, con una señal de código de chip de tiempo controlado que corresponde a una señal no diseminada respectiva, produciendo señales no diseminadas procesadas por espectro de diseminación N;un primer sustractor, para sustraer de la señal de 15 CDMA de espectro de diseminación, todas excepto, -una primera señal de las señales no diseminadas procesadas por espectro de diseminación N, generando así una primera señal sustraída;un segundo sustractor, para sustraer de la señal de CDMA de espectro de diseminación, todas excepto una segunda 20 señal de las señales no diseminadas procesadas por espectro de diseminación N, generando así una segunda señal sustraída;y un sustractor n avo , para sustraer de la señal de CDMA de espectro de diseminación, todas excepto una señal -5959 n ava ¿θ p as señales no diseminadas procesadas por espectro de diseminación N, generando así una señal sustraída n a ^ a ;un primer filtro adaptado de canal para no diseminar la primera señal sustraída con una primera señal de 5 código de chip como una estimación de un primer canal;un segundo filtro adaptado de capal para no diseminar la segunda señal sustraída con una segunda señal de código de chip como una estimación de un segundo canal;” un filtro adaptado de canal n avo para no diseminar 10 la señal sustraída n ava con una señal de código de chip n avo como una estimación de un canal n avo ;y medios para combinar una pluralidad de estimaciones del canal n avo a partir de la pluralidad de anuladores de interferencia.

Independent claims22

135 paragraphs in 7 sections, as filed

SYSTEM AND METHOD FOR CANCELING DISSEMINATION SPECTRUM INTERFERENCE

BACKGROUND OF THE INVENTION

This invention relates to wide-spectrum communications, and more particularly to an interference suppressor and a method for reducing interference in a direct-sequence, code-division multiple-access receiver.

DESCRIPTION OF THE PREVIOUS TECHNIQUE

Wide-spectrum, code-division multiple-access, direct-sequence communication systems are limited in their capacity by interference caused by other simultaneous users. This is exacerbated if adaptive power control is not used, or if it is used but not perfectly.

Code division multiple access (CDA) is interference-limited. The more users transmitting simultaneously, the higher the bit error rate (BER). Increased capacity requires forward error correction (FEC) coding, which in turn increases data rate but limits capacity.

BRIEF DESCRIPTION OF THE INVENTION 5

A general object of the invention is to reduce the noise resulting from Nl interference signals in a wide-spectrum, direct-sequence, code-division multiple-access receiver.

The present invention, as modalized and broadly described herein, provides a wide-spectrum code-division multiple access (CDMA) interference canceller for reducing interference in a wide-spectrum CDMA receiver having N channels. Each of the N channels is processed across a wide spectrum using a distinct chip code signal; the chip code signal is preferably derived from a distinct pseudo-noise (PN) sequence, which can be generated from a distinct chip code word. The interference suppressor partially cancels the CDMA channels of interference from N1, providing a signal-to-noise ratio (SNR) improvement of approximately N/PG, where PG is the processing gain. Processing gain is the ratio of chip speed to bit rate. By canceling or reducing interference, the SNR is primarily due to thermal noise and residual noise produced by the interference. In this way, SNR can increase, reduce the BER, which reduces the demand 5 for an FEC encoder/decoder.

The interference suppressor, for a particular channel, includes a plurality of means for non-disseminating a plurality of means for disseminating spectrum processing, means for subtraction, and means for non-disseminating the channel. Using a plurality of chip code signals, the plurality of means for non-disseminating does not disseminate the CDMA signals from the dissemination spectrum as a plurality of non-disseminated signals, respectively. The plurality of processing means for dissemination spectrum 15 uses a time version of a plurality of chip code signals to process as dissemination spectrum the plurality of non-disseminated signals, respectively, with a chip code signal corresponding to a respective non-disseminated signal. The time version of a chip code signal 20 can be generated by delaying the chip code signal from a chip code signal generator. Alternatively, a tailored filter can detect a particular PN sequence in the broadcast spectrum CDMA signal. A chip code signal generator can use the signal detected by the tailored filter to power on a time-domain version of the chip code signal.

To recover a particular CDMA channel using a chip code signal iavaThe subtraction methods subtract from the CDMA broadcast spectrum signal each of the non-broadcast signals processed by the broadcast spectrum N1, thus generating a subtracted signal. The non-broadcast signals processed by the broadcast spectrum N1 do not include the non-broadcast signal processed from the broadcast spectrum of channel iava g.EU corresponds to the chip code signal of iavaNon-channel disseminating media do not disseminate the stolen signal with the chip code signal iava.

The present invention also includes a method 15 for reducing interference in a spread spectrum CDMA receiver having N channels. The method comprises the steps of not disseminating, using a plurality of chip code signals, the dissemination spectrum CDMA signal as a plurality of non-disseminated signals, respectively; process the dissemination spectrum, using a time version of the plurality of chip code signals, the plurality of non-disseminated signals, respectively, with a chip code signal corresponding to a respective non-disseminated signal 2 5, subtract from the CDMA signal of dissemination spectrum, each of the non-disseminated signals processed by the dissemination spectrum Nl, with the non-disseminated signals processed with the dissemination spectrum Nl not including a disseminated np signal 5 processed with the dissemination spectrum of the iava channels, thus generating a subtracted signal; and, not disseminating the subtracted signal that has the chip code signal iava.

The objects and additional advantages of the present invention are partly set forth in the following description, and partly are obvious from the description, or can be learned by practicing the invention. These objects and advantages of the invention can also be achieved and obtained by means of the instruments and combinations particularly indicated in appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form part of the specification, illustrate preferred embodiments of the invention, and together with the description serve to explain the principles of the invention.

FIGURE 1 is a block diagram of the spread spectrum CDMA interference canceller using correlators;

Figure 2 is a block diagram of the CDMA spread spectrum interference canceller 5 for processing multiple channels using correlators; Figure 3 is a block diagram of the CDMA spread spectrum interference canceller using matched filters;10 FIGURE 4 is a block diagram of the spread spectrum CDMA interference canceller for processing multiple channels using matched filters;

FIGURE 5 is a block diagram of the Spread Spectrum CDMA Interference Canceller that 15 has multiple iterations to process multiple channels;

<td></td><td>the</td><td>FIGURE 6</td><td>illustrates</td><td>he</td><td>performance</td><td>theorist</td>

<td></td><td>characteristic the</td><td>for Eb/i| FIGURE 7</td><td>= 6 dB; illustrates</td><td>he</td><td>performance</td><td>theorist</td>

<td> 20</td><td>characteristic the</td><td>for E^/η FIGURE 8</td><td>= 10 dB; illustrates</td><td>he</td><td>performance</td><td>theorist</td>

<td></td><td>characteristic the</td><td>for Eb/Yo) FIGURE 9</td><td>= 15 dB; illustrates</td><td>he</td><td>performance</td><td>theorist</td>

<td></td><td>characteristic the</td><td>for Eb/Yo} FIGURE 10</td><td>= 20 dB; illustrates</td><td>he</td><td>performance</td><td>theorist</td>

<td> 25</td><td>characteristic</td><td>for Eb/q</td><td>= 25 dB;</td><td></td><td></td><td> ·</td>

FIGURE 11 illustrates the characteristic theoretical performance for E^/η = 30 dB;

FIGURE 12 is a block diagram of interconnected interference suppressors;

FIGURE 13 is a block diagram that combines the outputs of the interference cancellers from FIGURE 12;

FIGURE 14 illustrates simulation performance characteristics for Equal Asynchronous Energies 10 PG = 100, EbN = 30 dB;

FIGURE 15 illustrates simulation performance characteristics for asynchronous Equal Energies PG = 100, EbN = 30 dB;

FIGURE 16 illustrates simulation performance characteristics for asynchronous Equal Energies PG = 100, EbN = 30 dB; and FIGURE 17 illustrates simulation performance characteristics for asynchronous Equal Energies PG = 100, EbN = 30 dB.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES

Referring now in detail to the preferred embodiments of the present invention, 25 examples of which are illustrated in the accompanying drawings, wherein equal reference numbers indicate equal elements through various views.

In the illustrative arrangement shown in FIGURE 1, a 5-channel code division multiple access (CDMA) interference canceller is provided to reduce interference in a CDMA receiver having N channels. The present invention also works in a code division multiplexed (CDM) system. Therefore, without loss of generality, the term spread spectrum CDMA signal, as used herein, includes spread spectrum CDMA signals and spread spectrum CDM signals. In a personal communication service, the interference suppressor may be used at a base station or in a remote unit such as a microphone.

Figure 1 illustrates the interference suppressor for the first channel, defined by the first chip code signal. The interference suppressor includes a plurality of non-scattering means, a plurality of timing control means, a plurality of scattering spectrum processing means, subtraction means, and first channel non-scattering means.

Using a plurality of 25-chip code signals, the plurality of non-disseminating media do not disseminate the CDMA signals from the disseminating spectrum of the non-disseminating signals, respectively. In FIGURE 1, the plurality of non-disseminating media are shown as first non-disseminating media, second non-disseminating media, and 5 non-disseminating media.you.

The first non-disseminating media include a first correlator, which is modalized, by way of example, as a first mixer 51, a first chip code signal generator 52, and a first integrator 54. The first integrator 54 can alternatively be a first low-pass filter or a first band-pass filter. The first mixer 51 is coupled between input 41 and the first chip code signal generator 5 and the first integrator 54.

The second non-disseminating media include a second correlator, which is modalized, by way of example, as a second mixer 61, a second chip code signal generator 62, and a second integrator 64. The second integrator 64 can alternatively be a second low-pass filter 20 or a second band-pass filter. The second mixer 61 is coupled between input 41, the second chip code signal generator 62, and the second integrator 64.

The non-disseminating media Navos are 25 represented as a correlator Navo shown, in a way

-1010 for example, like the N mixeravo 71, and the N-chip code signal generatorava 72 and the integrator Navo 74. The integrator Navo 74, alternatively it can be an N low-pass filteravo or an N-bandpass filteravoThe 5 N mixeravo 71 is coupled between input 41, the chip code signal generator Nava 72 and the Navo 74 integrator.

As is well known in the field, the first non-disseminating N mediayou They can be modalized as any device, which may not disseminate a channel in a dissemination spectrum signal.

The plurality of time control means can be modalized as a plurality of delay devices 53, 63, 73. A first delay device 53 has a delay time T, which is approximately equal to the integration time Tb of the first integrator 54, or the time constant of the first low-pass filter or the first band-pass filter. A second delay device 63 has a time delay T, which is approximately equal to the integration time Tb of the second integrator 64, or the time constant of the second low-pass filter or the second band-pass filter. Similarly, the delay device Navo 73 has a time delay T, which is approximately equal to the integration time

Tb from the integrator Navo 74, or the time constant of

-1111 N low-pass filteravo or the N-bandpass filteravoTypically, the integration times of the first integrator are 54, the second integrator 64, and the integrator N.avo 74, are equal. If low-pass filters are used, then typically the time constants of the first low-pass filter, the second low-pass filter, to the N low-pass filteravo are equal. If bandpass filters are used, then the time constants of the first bandpass filter, the second bandpass filter, and the Nth bandpass filter are the same.avo They are the same.

The plurality of dissemination spectrum processing means regenerates each of the plurality of non-disseminated signals as a plurality of dissemination spectrum signals. The plurality of dissemination spectrum processing means uses a time version, i.e., a delayed version, of the plurality of chip code signals, for dissemination spectrum processing of the plurality of non-disseminated signals, respectively, with a chip code signal corresponding to a respective non-disseminated signal. The plurality of dissemination spectrum processing means is shown, by way of example, as a first processing mixer 55, a second processing mixer 65 up to a processing mixer Navo 75. The first processing mixer 55 is coupled to the

-1212 ' first integrator 54, and through a first delay device 53 to the first chip code signal generator 52. The second processing mixer 65 is coupled to the second integrator 64, and through the second delay device 63 to the second chip code signal generator 62. The processing mixer Navo 75 is coupled to the integrator Navo 74 through the delay device 73 to the chip code signal generator Nava 72.

!ñ.u reduce interference to a channel that uses a chip code signal iava From the CDMA broadcast spectrum signal, the subtraction means subtract, from the CDMA broadcast spectrum signal, each of the processed non-broadcast broadcast spectrum signals Nl that do not correspond to channel iavoThe Ί5 subtraction means thus generate a subtracted signal. The subtraction means are shown as a first subtractor 150. The first subtractor 150 is shown coupled to the output of the second processing mixer 65, via the processing mixer Navo 75. In addition, the first subtractor 150 is coupled through a main delay device 48 to output 41.

Non-disseminating media of channel iavoNoThey disseminate the stolen signal with the chip code signal.as channel iavoThe first non-disseminating channel 25 media are shown as a first channel mixer 147.

-13The first channel mixer 147 is coupled to the first delay device 53, and to the first subtractor 150. The first channel integrator 146 is coupled to the first channel mixer 147.

The first chip code signal generator 52, the second chip code signal generator 62, to the chip code signal generator Nava 72 generate a first chip code signal, a second chip code signal, and the reverse of a chip code signal Navarespectively. The term chip code signal is used herein to denote the dissemination signal of a dissemination spectrum signal, as is well known in the art. Typically, the chip code signal is generated from a pseudorandom sequence (PN). The first chip code signal, the second chip code signal, through the chip code signal Nava They can be generated from a first PN sequence, a second PN sequence, or through a PN sequence, respectively. The first sequence

PN is defined by or generated from a first chip keyword, the m-second PN sequence is defined by or generated from a second chip keyword, through the sequence PN Nava that is defined by or generated by a chip keyword NavaEach of the first chip keyword, the second chip keyword through'

-1414 the keyword for chip Nava It is distinct, that is, different from one another. In general, a chip keyword can be used to define the actual sequence of a PN sequence, or it can be used to define fixes to generate the PN sequence. The fixes can be delay leads from change recorders, for example.

A first channel of a CDMA broadcast spectrum signal received at input 41 is not broadcast by the first mixer 51 as a first non-broadcast signal, using the first chip code signal generated by the first chip code signal generator 52. The first non-broadcast signal from the first mixer 51 is filtered through the first integrator 54. The first integrator 54 integrates for a time T^, the duration of a symbol tai as a bit. At the same time, the first chip code signal is delayed by time T by the delay device 53. The delay time T is approximately equal to the integration time plus the system or component delays. System or component delays are usually small compared to the integration time.

The delayed version of the first chip code signal is processed with the first undisseminated signal from the output of the first integrator 54, using the first dissemination mixer 55. The output of the first mixer

-1515 of dissemination 55 is fed to subtractors other than the first subtractor 150 to process the second CDMA signal of dissemination spectrum through the N channelsyou.

To reduce interference to the first channel of the broadcast spectrum CDMA signal, the received broadcast spectrum CDMA signal is processed by the second channel through non-broadcasters.youas follows. The second channel of the CDMA signal from the dissemination spectrum 10 is not disseminated by the second non-disseminating media. In the second mixer 61, a second chip code signal, generated by the second chip code signal generator 62, is not disseminated to the second channel of the CDMA signal from the dissemination spectrum. The second non-disseminated channel 15 is filtered through the second integrator 64.

The output of the second integrator 64 is the second non-disseminated signal. The second non-disseminated signal is processed using the dissemination spectrum by the second processing mixer 65 using a delayed version of the second chip code signal 20. The second chip code signal is delayed by the delay device 63. The delay device 63 delays the second chip code signal by a time T. The second channel 65 mixer processes by means of dissemination spectrum a 25-time version, i.e. a delayed version of the second signal

-1616 chip code with the filtered version of the second spread spectrum channel of the second integrator 64. The term spread spectrum procedure as used herein, includes any method for generating a 5 spread spectrum signal by mixing or modulating a signal with a chip code signal. Dissemination spectrum processing can be done using product devices, EXCLUSIVE-OR gates, adapted filters, or any other device or circuit well known in the art.

Similarly, the N channelavo The CDMA signal dissemination spectrum is not disseminated by non-disseminating means NyouTherefore, the received broadcast spectrum CDMA signal has the N channelavo not dispersed by mixer Navo 71, mixing the CDMA 15 broadcast spectrum signal with the chip code signal

Nava?and]_ chip code signal generator Nava 72. The outlet of mixer Navo 71 is filtered by the Navo integrator 74. The output, from integrator Navo 74, which is the non-disseminated N signalava, is a non-disseminated and filtered version of the N-channelavo of the CDMA broadcast spectrum signal. The non-broadcast N signalava It is processed by the dissemination spectrum using a delayed version of the N-chip code signalavaThe code signal of the N chipavais delayed through the N delay deviceavo 73. The 25 N processing mixeravo 75 processes using spectrum

-1717 dissemination time version, i.e., a delayed version of the chip code signal Nava with the non-disseminated N signalava.

In the first subtractor 150, each of the outputs of the second processing mixer 65 through the processing mixer Navo 75 is subtracted from a time version, i.e., a delayed version of the CDMA broadcast spectrum signal from input 41. The delay of the CDMA broadcast spectrum signal is time-controlled through the first delay device 48. Typically, the delay of the first main delay device 48 is time T, which is approximately equal to the integration time of the first integrator 54 through integrator Navo 74.

At the output of the first subtractor 150, a first subtracted signal is generated. The first subtracted signal, for the first channel of the CDMA broadcast spectrum signal, is defined herein as the outputs of the second processing mixer 65 through the processing mixer Navo 75, extracted from the delayed version of the CDMA broadcast spectrum signal. The second signal extracted via the N-selected signalto^to is similarly defined.

The delayed version of the first chip code signal from the output of the first delay device 53-es

-1818 is used to prevent the first subtractor's output from being disseminated. Consequently, the first subtracted signal is not disseminated by the first chip code signal through the first channel mixer (147). The output of the first channel mixer (147) is filtered through the first channel integrator (147). This produces an output estimate of the first channel's CDMA dissemination spectrum signal.

As illustrated in FIGURE 2, a plurality of subtractors 150, 250, 350, 450 can be appropriately coupled to the inlet 41 and to a first dissemination mixer 55, a second dissemination mixer 65, a third dissemination mixer, up to a dissemination mixer Navo Figure 1, Figure 75, shows a plurality of subtractors 150, 250, 350, and 450, also coupled to the main delay device 48 from input 41. This arrangement can generate a first signal.

<td>stolen</td><td>of the first subtractor</td><td> 150,</td><td>a</td><td>second</td><td>sign</td>

<td>stolen</td><td>of the second subtractor</td><td> 250,</td><td>a</td><td>third</td><td>sign</td>

<td>stolen</td><td>from the third subtractor 350</td><td>until</td><td>a</td><td colspan="2">stolen signal</td>

<td colspan="2">Navato starting from a subtractor Navo</td><td> 450 .</td><td></td><td></td><td></td>

The outputs of the first subtractor 150, the second subtractor 250, the third subtractor 350, up to the subtractorNavo 450, are each coupled to a first channel mixer 147, second channel mixer 247, third channel mixer 347, respectively, up to the channel mixer Navo

-1919

447. Each of the channel mixers is coupled to a delayed version of the first chip code signal, g1(tT), second chip code signal, g2 (tT) , third chip code signal, g3(tT), up to the chip code signal Nava, gN(tT) . The outputs of each of the first channel mixer 147, the second channel mixer 247, the third channel mixer 347 respectively, up to the channel mixer Navo 447 are coupled to a first channel 146 integrator, second channel 246 integrator, third channel 346 integrator up to the N channel integratoravo 446, respectively. At the output of each of the channel integrators, an estimate of the first channel dp and the second channel d is produced.2, third channel d3, respective, up to channel Navo djj.

Referring to FIGURE 1, the use of the present invention is illustrated for the first channel of the CDMA broadcast spectrum signal, with the understanding that the second through the CDMA N channelsyou They work similarly. A spread spectrum CDMA signal received at input 41 is delayed by delay device 48 and fed to the first subtractor 150. The spread spectrum CDMA signal has the second channel up to the N channelavo not disseminated by the second mixer 61 using the second chip code signal, through mixer Navo 71 using the chip code signal Nava.

-202 0

The second chip code signal corresponding to the chip code signal Nava are generated by the second chip code signal generator 62 up to the chip code signal generator Nava 72. The second channel up to the N channelavo5 They are not disseminated and filtered through the second integrator 64 to the integrator Navo 74, respectively. Non-dissemination removes, partially or totally, the non-disseminated channels at the outputs of each of the second integrator 64 up to integrator Navo 74.

In a preferred embodiment, each of the chip code signals used for the first chip code signal generator 52, the second chip code signal generator 62 up to chip code signal generator Nava72 are orthogonal to each other. The use of 15 chip code signals that are orthogonal, however, is not required for the operation of the present invention. When orthogonal chip code signals are used, the non-disseminated signals have the respective channels plus noise at the output of each integrator. With 20 orthogonal chip code signals, theoretically the mixers remove channels orthogonal to the non-disseminated channel. The respective channel is processed by the dissemination spectrum through the respective processing mixer.

-2121

At the outlet of the second processing mixer to processing mixer Navo 75, there is a re-seeded version of the second channel up to the N channelavo, plus the noise components contained therein. Each 5 from the second channel to the N channelavo It is subtracted after the CDMA broadcast spectrum signal received by the first subtractor 150. The first subtractor 150 produces the first subtracted signal. The first subtracted signal is not broadcast by a delay version of the first 10-chip code signal by the first channel mixer 147, and mixed by the first channel filter 146. Therefore, before not disseminating the first channel of the CDMA signal dissemination spectrum, the second channel up to the N channelavo The noise components aligned with these channels are subtracted from the received CDMA broadcast spectrum signal. As illustrated in FIGURE 3, an alternative modality of the CDMA broadcast spectrum interference canceller includes a plurality of first non-broadcasting media, a plurality of broadcast spectrum processing media, subtraction media, and second non-broadcasting media. In FIGURE 3, the plurality of non-disseminating media is shown as first non-disseminating media, second non-disseminating media up to non-disseminating media NyouThe first media

-2222 disseminators are configured as a first adapted filter 154. The first adapted filter 154 has a pulse response adapted to the first chip code signal, which is used for dissemination spectrum processing and defines the first channel of the CDMA dissemination spectrum signal. The first adapted filter 154 is coupled to input 41.

The second non-disseminating media is shown as a second adapted filter 164. The second adapted filter 164 has a pulse response adapted to the second chip code signal, which is used for the dissemination spectrum procedure and defines the second channel of the dissemination spectrum CDMA signal. The second filter 164 is coupled to input 41.

Non-disseminating media Nyou They are shown in an adapted N filter.avo 174. The adapted filter Navo It has a pulse response adapted to the N-chip code signal.avawhich is used for the dissemination spectrum procedure and defines the N channelavo of the CDMA signal of 20 dissemination spectrum. The N-adapted filteravo It is coupled to input 41.

The term 'adapted filter', as used here, includes any type of adapted filter that can be adapted to a chip code signal. Adapted filter 25 can be a digital adapted filter or an adapted filter.

-2323 analog. A surface acoustic wave (SAW) device can be used at radio frequency (RF) or intermediate frequency (IF). Digital signal processors and the application of specific integrated circuits (ASICs) have nine matching filters, which can be used at RF, IF, or baseband frequencies.

In FIGURE 3, the plurality of scatter spectrum processing means are shown as the first processing mixer 55, the second processing mixer 65, up to the processing mixer Navo

75. The first processing mixer 55 can be coupled via a first adjustment device 97 to the first chip code signal generator 52. The second processing mixer 65 can be coupled via a second adjustment device 98 to the second chip code signal generator 62. The Navo processing mixer 75 can be coupled via the adjustment deviceN73rdto the N-chip code signal generatorava 72. The first adjustment device 97, the second adjustment device 98 up to the adjustment device Navo 99 are optional, and are used as an adjustment to align the first chip code signal, the second chip code signal up to the chip code signal with the first non-disseminated signal, the second non-disseminated signal up to the non-disseminated signal Nava, which comes out of the first adapted filter

-2424

154, the second adapted filter 164 up to the adapted filter NavEITHERYo respectively.

The subtraction means are shown as the first subtractor 150. The first subtractor 150 is coupled 5 to the output of the second processing mixer 65 up to the processing mixer Navo 75. In addition, the first subtractor 150 is coupled via the main delay device 48 to input 41.

The first non-spreading channel media 10 is shown as a first channel-adapted filter 126. The first channel-adapted filter 126 is coupled to the first subtractor 150. The first channel-adapted filter 126 has a pulse response adapted to the first chip code signal.

The first channel of a received CDMA broadcast spectrum signal, at input 41, is not broadcast by the first matched filter 154. The first matched filter 154 has a pulse response matched to the first chip code signal. The first chip code signal defines the first channel of the CDMA broadcast spectrum signal and is used by the first chip code signal generator 52. The first chip code signal can be delayed by adjusting the time r using adjustment device 97. The output of the first adapted filter 154 is processed using the spectrum - of

-2525 dissemination by the first processing mixer 55 with the first chip code signal. The output of the first processing mixer 55 is fed to subtractors other than the first subtractor 150 to process the second channel 5 through the N channelavo of the CDMA broadcast spectrum signals.

To reduce interference to the first dissemination spectrum channel, the CDMA dissemination spectrum signal is processed by the second non-dissemination media through the non-dissemination media Nyouas follows. The second adapted filter 164 has an impulse response adapted to the second chip code signal. The second chip code signal defines the second channel of the CDMA broadcast spectrum signal and is used by the second chip code signal generator 62. The second adapted filter 164 does not broadcast to the second channel of the CDMA broadcast spectrum signal. The output of the second adapted filter 164 is the second non-broadcast signal. The second non-disseminated signal triggers the second chip code signal generator 62. The second non-disseminated signal is also processed by dissemination spectrum by the second processing mixer 65 using a time-controlled version of the second chip code signal. The time controller of the

-2626 second chip code signal triggers the second non-disseminated signal of the second adapted filter 164.

Similarly, the N channelavo The CDMA signal dissemination spectrum is not disseminated by non-5 disseminators NyouTherefore, the received broadcast spectrum CDMA signal has the N channelavo not disseminated by the adapted N filteravo 174. The output of the adapted Nava 174 filter, the non-disseminated signal NavaThat is, a non-disseminated and filtered version of the N-channelavo of the CDMA broadcast spectrum signal. The non-broadcast N signalto^to is processed by the scatter spectrum by a time-controlled version of the N-chip code signalav®. The N™ Chip Code Signal Timing Controlleris activated by signal no. 15 disseminated Nava of the adapted filter Navo 174. The N Processing Mixeravo 75 processes the time-controlled version of the chip code signal N using dissipation spectrumava with the non-disseminated N signalava.

In the first subtractor 150, each of the 20 outputs of the second processing mixer 65 up to the processing mixer Navo 75 are subtracted from a delayed version of the CDMA broadcast spectrum signal from input 41. The delay of the CDMA broadcast spectrum signal is controlled at time 25 through delay device 48. The time of the

-27 delay device 48 is set to align the second signal through the non-scattered signals processed by the N scatter spectrumavo for subtracting the CDMA signal from the broadcast spectrum. This generates a first subtracted signal at the output of the first subtractor (150). The subtracted signal is not broadcast by the first channel-matched filter (126). This produces an output estimate of dT of the first channel of the CDMA signal spectrum dissemination.

.10 As illustrated in FIGURE 4, a plurality of subtractors 150, 250, 350, 450 can be suitably coupled to the output of a first processing mixer, second processing mixer, third processing mixer, up to a processing mixer Navo, already a main delay device from the input. A first subtracted signal comes from the first subtractor 150, a second subtracted signal comes from the second subtractor 250, a third subtracted signal comes from the third subtractor 350 through a subtractor signal Nava that comes out of a subtractor Navo 450.

The output of the first subtractor is 150, the second subtractor 250, the third subtractor 350, up to the subtractorNavo 450, are coupled to a first adapted filter of channel 126 respectively, second adapted filter of channel 226, 25 third adapted filter of channel 326, up to the adapted filter

-2828 on channel Navo 426. The first adapted filter of channel 126, the second adapted filter of channel 226, the third adapted filter of channel 326 up to the adapted filter of channel Navo426 They have a pulse response adapted to the first chip code signal, the second chip code signal, the third chip code signal, up to chip code signal Nava, defining the first channel, the second channel, the third channel, through the N channelavorespectively, of the CDMA broadcast spectrum signal. At each of the outputs of the first channel 126 matched filter, the second channel 226 matched filter, the third channel 326 matched filter, up to the N-channel matched filteravo 426, respectively, an estimate of the first channel d1 is produced (the second channel d2, the third channel d3, up to the N channelavo respective dn.

During use, the present invention is illustrated for the first channel of the CDMA broadcast spectrum signal, with the understanding that the second channel up to the N channelavo They work similarly. A spread spectrum CDMA signal received at input 41 is delayed by delay device 48 and fed to subtractor 150. The same spread spectrum CDMA signal then travels through channel N.avo not disseminated by the second adapted filter 164 up to the adapted filter Navo 174. This non-dissemination removes the others

-2929 CDMA channels of the respective non-dissemination channel. In a preferred mode, each of the chip code signals used for the first channel, second channel, up to the N channelavoIt is orthogonal to the other 5-chip code signals. At the output of the first matched filter 154, the second matched filter 164 up to the matched filter Navo 174, the first non-disseminated signal is found, the second non-disseminated signal up to the non-disseminated signal Nava, more noise.

The respective channel is processed by dissemination spectrum 10 through the processing mixers.

Therefore, at the outlet of the second processing mixer 65 up to the processing mixer Navo 75, a dissemination version of the second non-disseminated signal is found through the non-disseminated signal Navaplus 15 the noise components contained therein. Each of the non-spread signals processed by the spread spectrum is then subtracted from the CDMA spread spectrum signal received by the first subtractor 150. This produces the first subtracted signal. The first 20 subtracted signal is non-spread by the first channel-matched filter 126. Consequently, before not disseminating the first channel of the CDMA signal dissemination spectrum, the second channel up to the N channelavo Plus the noise components aligned with these channels, are subtracted from the CDMA broadcast spectrum signal.

-3030

As is well known in the field, correlators and matched filters can be interchanged to achieve the same function. Figures 1 and 3 show alternative configurations using either correlators or matched filters. The arrangements can be varied. For example, a plurality of non-spreading media can be configured as a plurality of matched filters, while the non-spreading channel media can be configured as a single correlator. Alternatively, the plurality of non-disseminating media can be a combination of matched filters and correlators. Also, the disseminating spectrum processing media can be configured as a matched filter or SAW, or EXCLUSIVE-O gates, or other devices to mix a non-disseminated signal with a chip code signal. As is well known in the art, any non-spreading spectrum disseminator or demodulator may not disseminate the CDMA broadcast spectrum signal. The particular circuits shown in FIGURES 1-4 illustrate the invention by way of example.

The concepts taught in FIGURES 1-4 can be repeated, as shown in FIGURE 5. FIGURE 5 illustrates a first plurality of interference cancellers 511, 512, 513, a second plurality of interference cancellers 521, 522, 523, up to a plurality Nava · of

-3131 interference suppressors 531, 532, 533. Each plurality of interference suppressors includes appropriate elements as already described, and referring to FIGURES 1-4. The input is delayed through a delay device in each interference suppressor.

The received broadcast spectrum CDMA signal has interference initially canceled by the first plurality of interference cancellers 511, 512, 513, thus producing a first set of estimates, i.e., a first estimate d1:La second estimate d12, up to an estimated Nava d1N, from the first channel, second channel up to the N channelavo, of the CDMA broadcast spectrum signal. The first group of estimates may have the interference canceled by the second plurality of interference cancellers 521, 522, 523. The first group of estimates d1;L, d12, ..., d1N, from the first channel, from the second channel up to the N channelavo, they enter the second plurality of interference suppressors, interference suppressor 521, interference suppressor 522 up to interference suppressor Navo 523 of the second plurality of interference annihilators. The second plurality of interference annihilators thus produces a second group of estimates, namely, d21, d22, . ...., d2Nfrom the first channel, second channel, up to the N channelavoSimilarly, the second group of estimates can be passed on

-3232 through a third plurality of interference cancellers, and finally through an M groupavo of interference suppressors 531, 532, 533, respectively.

The present invention also includes a method for reducing interference in a spread-spectrum CDMA receiver having N chip-code channels. Each of the N channels is identified by a distinct chip-code signal. The method comprises the steps of non-spreading, using a plurality of chip-code signals, the spread-spectrum CDMA signal as a plurality of non-spread signals, respectively. Using a time-controlled version of the plurality of chip code signals, the plurality of non-disseminated signals are processed by dissemination spectrum with a chip code signal corresponding to a respective non-disseminated signal. Each of the non-disseminated signals processed by dissemination spectrum Nl, is subtracted from the CDMA dissemination spectrum signal, with the non-disseminated signals processed by dissemination spectrum Nl not including a signal processed by dissemination spectrum of the non-disseminated signal iavathus generating a subtracted signal. The subtracted signal is not disseminated to generate the i-channelavo.

The probability of error Pand For the CDMA 25 broadcast spectrum system, direct sequence is:

-333 3

Pand = lerfc (aSNR)* where erfc is a complementary error function, SNR is the signal-to-noise ratio, and 1 so? < 2 . The value of a depends on how a particular interference cancellation system is designed.

The SNR after interference cancellation, and method, is given by:

SNR = (PG/N)R’1

1*(PG/N)R*1_2_

ANDb/7

1- (N/PG)®*1

1-N/PG where N is the number of channels, PG is the processing gain, R is the number of repetitions of the interference canceller, is the energy per bit of information and η is the noise power spectrum density.

Figure 6 illustrates the characteristic theoretical performance of the interference suppressor and Method 15 when E^(i) = 6 dB. The performance characteristic is illustrated for SNR without the interference suppressor, versus PG/N. The lowest curve, for R = 0, is the performance without the interference suppressor. The curves for R = 1 and R = 2 illustrate the improved performance for using one or two iterations of the interference suppressor, as shown in

Figure 5. Since PG/N --> 1, there is insufficient SNR for operation. If PG > N, then the output SNR of the interference canceller approaches Eb/q. Furthermore, if (N/PG)^+1 << 1, then

SNR (Eb/q) (1 - N/PG).

Figure 7 illustrates the characteristic z- yield for when Eb/q = 10 dB. FIGURE 7 illustrates that three xO iterations of the interference canceller can produce a 4 dB improvement with PG/N = 2.

Figure 8 illustrates the characteristic performance for when Eb/q = 15 dB. With this bit-to-noise power ratio, two iterations of the interference canceller 15 can produce a 6 dB improvement for PG/N = 2.

Figure 9 illustrates the characteristic performance for when E^/q = 20 dB. With this bit-to-noise power ratio, two iterations of the interference canceller can produce a 6 dB improvement for PG/N = 2.

Similarly, FIGURES 10 and 11 show that one iteration of the interference canceller can produce an improvement greater than 10 dB for PG/N = 2.

The present invention can be extended to a plurality of interference cancellers. As shown in Figure 12, a received scatter spectrum signal,

-353 5

R(t) is non-disseminated and detected by the CDMA/DS 611 detector. Each of the channels is represented as outputs °01' °02' °03' · · · ' °0m-Summer In this way, each output is a dissemination spectrum channel, not disseminated from a received dissemination spectrum signal, R(t).

Each output of the CDMA/DS detector 611 is passed through a plurality of interference suppressors 612, 613, ..., 614, which are serially connected. Each broadcast spectrum channel passes through the interference suppression procedures as previously discussed. The input to each interference suppressor is achieved by checking and holding the output of the previous stage once per bit time. For channel i, the first interference canceller checks the output of the CDMA/DS detector at time t = T + ψ. This value remains constant as the input until t = 2T + 7if At this point, the following bit value is verified. In this way, the input waveforms to the interference canceller are calculated, - 7·), from the original data waveform, d¿ (t , and the outputs are second values dT'L (t - r^) . The outputs of the dissemination spectrum channel M Oq^, i = 1,2- ··., M, are passed through interference canceller 612 to produce a corresponding new group of channel O outputsLiz i = 1, 2, . . ., M.

-3636

As shown in FIGURE 13, the outputs of a particular broadcast spectrum channel, which are at the output of each of the interference suppressors, can be combined. Consequently, combiner 615 can combine the output of the first channel, which is from the CDMA/DS detector 611, and the output 0 of the first interference suppressor 612, and the output 021 from the second interference suppressor 613, through the Oni output from the interference suppressor Navo 614. Each output to be combined is of the corresponding bit. Therefore, bit time delays are inserted for each 0slThe combined outputs are then passed through a decision device 616. This can be done for each broadcast spectrum channel, and therefore designates the outputs of each of the combiners 615, 617, 619 as averaged outputs for channel one, averaged outputs 02, for channel two and averaged outputs OM for channel M. Each of the averaged outputs is passed sequentially through decision device 616, decision device 618, and decision device 620. Preferably, the averaged outputs have a multiplication factor cj, which can vary according to a particular design. In a preferred embodiment, cj = 23/10. This allows the outputs

-3737 of several interference suppressors are combined in a particular way.

Figures 14-17 illustrate a simulation performance characteristic of the arrangement in Figures 12 and 13. Figures 14-17 are for the asynchronous channel (relative time delays are uniformly distributed between 0 and bit time, T), a processing gain of 100, all users have equal power, and a thermal signal-to-noise ratio (E^N) of 30 dB. Gold codes with a length of 8191 are used for the PN sequences.

In FIGURE 14, the characteristic performance of each of the output stages in FIGURE 12 is shown. Thus, SO represents the BER performance at the output of the CDMA/DS detector 611, SI represents the BER performance at the output of the interference canceller 612, S2 represents the BER performance at the output of the interference canceller 613, etc. No combination of the interference suppressor outputs is used to determine the characteristic performance shown in Figure 14. Rather, the characteristic performance is for repeated use of the interference suppressors. For guidance, in each of the subsequent figures, the output for each feature of the CDMA/DS 611 detector is shown.

-3838

Figure 15 shows the characteristic performance when the outputs of the subsequent interference suppressors are combined. This is shown for a particular channel. Thus, curve SO represents the output of CDMA/DS detector 611. Curve SI represents the BER performance of the average of the outputs of CDMA/DS detector 611 and interference suppressor 612. Here, Cq = C^ = 1/2 Cj = 0, where j is not equal to zero, but one. The S2 curve represents the BER performance of the average output of interference suppressor 613 and interference suppressor 612. The S2 curve is determined using the combiner shown in FIGURE 13. Here, C-¡_ and C2 They are set equal to 1/2 and the entire other set Cj at zero. Similarly, curve S3 is the output performance of a second and third interference suppressor averaged together. Thus, curve S3 is the characteristic performance of the average between the output of a second interference suppressor and a third interference suppressor. Curve S4 is the characteristic performance of the average input of a third and fourth interference suppressor. Only two interference suppressors are considered at the time to determine a characteristic performance of an average output of those particular interference suppressors. Figure 16 shows the regular outputs for the CDMA/DS detector 611, and a first and second interference suppressor 612, 613.

-393S

Furthermore, the average output of the CDMA/DS detector 611 and the first interference suppressor 612 is shown as S1 AVG. The EIER performance of the average outputs of the first interference suppressor 612 and the second interference suppressor 613 is shown as the average output S2 AVG.

FIGURE 17 shows the characteristic performance corresponding to that of FIGURE 16, but in terms of signal-to-noise ratio in decibels (dB).

It will be evident to those skilled in the art 10 that various modifications can be made to the spread spectrum CDMA interference suppressor and method of the present invention without departing from its scope or spirit; it is intended that the present invention covers modifications and variations of the spread spectrum CDMA interference suppressor and method provided, so that they are within the scope of the attached claims and their equivalents.

Contents7

129 members in 17 offices

This recordMember, by publication datePriority claim7 more offices are in the list below

Priority claims2

Priority claims
Document	Office	Kind	Date
27947794	United States of America	A	1994-07-26
9509652	United States of America	W	1995-07-05

Members129

Family members, oldest first
Document	Office	Kind
US5363403A	United States of America	A	1994-11-08
CA2195534A1	Canada	A1	1996-02-08
CA2342454A1	Canada	A1	1996-02-08
CA2369499A1	Canada	A1	1996-02-08
CA2552443A1	Canada	A1	1996-02-08
WO9603819A1	World Intellectual Property Organization (WIPO)	A1	1996-02-08
AU3154195A	Australia	A	1996-02-22
US5553062A	United States of America	A	1996-09-03
FI970276A	Finland	A	1997-01-23
FI970276A7	Finland	A7	1997-01-23
SE9700184D0	Sweden	D0	1997-01-23
DK8997A	Denmark	A	1997-01-24
SE9700184L	Sweden	L	1997-03-26
EP0772928A1	European Patent Office (EPO)	A1	1997-05-14
CN1154770A	China	A	1997-07-16
BR9508348A	Brazil	A	1998-01-06
US5719852A	United States of America	A	1998-02-17
NZ314383A	New Zealand	A	1998-02-26
JPH10504429A	Japan	A	1998-04-28
NZ290723A	New Zealand	A	1998-05-27
MX9700522AThis record	Mexico	A	1998-05-31
DE19581709T1	Germany	T1	1998-10-29
AU701816B2	Australia	B2	1999-02-04
EP0772928A4	European Patent Office (EPO)	A4	1999-10-13
ES2137140T1	Spain	T1	1999-12-16
DE772928T1	Germany	T1	1999-12-30
US6014373A	United States of America	A	2000-01-11
EP1033840A1	European Patent Office (EPO)	A1	2000-09-06
ES2151461T1	Spain	T1	2001-01-01
DE1033840T1	Germany	T1	2001-02-08
JP2001053721A	Japan	A	2001-02-23
JP3153894B2	Japan	B2	2001-04-09
HK1030697A1	Hong Kong, China	A1	2001-05-11
US6259688B1	United States of America	B1	2001-07-10
US2001019548A1	United States of America	A1	2001-09-06
CA2195534C	Canada	C	2001-10-09
CN1337797A	China	A	2002-02-27
CA2342454C	Canada	C	2002-09-03
EP0772928B1	European Patent Office (EPO)	B1	2002-09-18
CN1373581A	China	A	2002-10-09
CN1373582A	China	A	2002-10-09
CN1373583A	China	A	2002-10-09
AT224618T	Austria	T	2002-10-15
ATE224618T1	Austria	T1	2002-10-15
DE69528275D1	Germany	D1	2002-10-24
US2002167925A1	United States of America	A1	2002-11-14
US2002172171A1	United States of America	A1	2002-11-21
US2002172172A1	United States of America	A1	2002-11-21
US2002172173A1	United States of America	A1	2002-11-21
US2002186673A1	United States of America	A1	2002-12-12
US2002191571A1	United States of America	A1	2002-12-19
CN1097368C	China	C	2002-12-25
US2002196757A1	United States of America	A1	2002-12-26
US2003002463A1	United States of America	A1	2003-01-02
DK0772928T3	Denmark	T3	2003-01-13
JP3377983B2	Japan	B2	2003-02-17
DE69528275T2	Germany	T2	2003-05-08
ES2137140T3	Spain	T3	2003-05-16
DK200300950A	Denmark	A	2003-06-25
DK200300951A	Denmark	A	2003-06-25
HK1050965A1	Hong Kong, China	A1	2003-07-11
HK1050966A1	Hong Kong, China	A1	2003-07-11
HK1050967A1	Hong Kong, China	A1	2003-07-11
SE0302105D0	Sweden	D0	2003-07-21
SE0302105L	Sweden	L	2003-07-21
SE521137C2	Sweden	C2	2003-10-07
CN1490966A	China	A	2004-04-21
CN1501611A	China	A	2004-06-02
CN1503493A	China	A	2004-06-09
CN1165125C	China	C	2004-09-01
HK1065190A1	Hong Kong, China	A1	2005-02-08
FI20050232A	Finland	A	2005-03-01
FI20050232L	Finland	L	2005-03-01
US6868076B2	United States of America	B2	2005-03-15
US6868078B2	United States of America	B2	2005-03-15
HK1066657A1	Hong Kong, China	A1	2005-03-24
HK1066945A1	Hong Kong, China	A1	2005-04-01
US6876665B2	United States of America	B2	2005-04-05
FI115430B	Finland	B	2005-04-29
US2005157743A1	United States of America	A1	2005-07-21
CN1223127C	China	C	2005-10-12
CN1228937C	China	C	2005-11-23
CN1229935C	China	C	2005-11-30
SE0502763L	Sweden	L	2005-12-15
SE527579C2	Sweden	C2	2006-04-11
US7027423B2	United States of America	B2	2006-04-11
CN1252957C	China	C	2006-04-19
FI20060855A7	Finland	A7	2006-09-26
FI20060855L	Finland	L	2006-09-26
FI20060855L	Finland	L	2006-09-26
FI117612B	Finland	B	2006-12-15
DK176193B1	Denmark	B1	2007-01-02
US7161919B2	United States of America	B2	2007-01-09
US7164668B2	United States of America	B2	2007-01-16
US7167462B2	United States of America	B2	2007-01-23
US7167464B2	United States of America	B2	2007-01-23
SE0700241L	Sweden	L	2007-02-01
DK200700410A	Denmark	A	2007-03-19
DK200700411A	Denmark	A	2007-03-19
SE528965C2	Sweden	C2	2007-03-27

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