Spread spectrum microwave overlay with notch filter

• US 6,115,368 A
• Filed: 01/21/1994
• Issued: 09/05/2000
• Est. Priority Date: 05/15/1991
• Status: Expired due to Term

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Inventors: Schilling, Donald L.
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US08/272,498
• Time in Patent Office: 2,419 Days
• Field of Search: 370/320, 370/335, 370/342, 370/441, 370/321, 375/200, 455/454, 455/513
• US Class Current: 370/335
• CPC Class Codes: H04B 1/71 the interference being narrowband interference
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level
• CPC Class Codes: H04W 52/346 distributing total power among users or channels

Abstract

A spread spectrum CDMA communications system for communicating data and/or digitized voice between a plurality of users to a plurality of PCN units. The spread spectrum communications system is located within a same geographical region as occupied by an existing microwave system. The spread spectrum can operate without causing undue interference to the microwave system and the microwave system can operate without causing significant interference, less than 1% total users affected, to the PCN system. The spread spectrum CDMA communications system includes a plurality of PCN-base stations and a plurality of PCN units. A PCN-base station has a device for converting the format of the data into a form suitable for communicating over radio waves, a spread spectrum modulator for spread spectrum processing the data, a notch filter, and a transmitter for transmitting the spread spectrum processed converted data from the PCN-base station to a PCN unit. The PCN-base station also has an antenna, and spread spectrum detectors for recovering data communicated from the PCN units. A PCN unit has an antenna, and a detector coupled to the antenna for recovering data communicated from the PCN-base station. The detector includes a spread spectrum demodulator. Also, the PCN unit has a device for converting the format of the data into a form suitable for communicating over radio waves, a spread spectrum modulator, an adjustable notch filter and a transmitter.

Claims

1. A method for communicating in a spread spectrum code division multiple access (CDMA) communication system having a transmitter and a receiver co-existing with a microwave system, the microwave system selectively utilizing various microwave frequencies within a selected range of frequencies, the method comprising:

generating a spread spectrum CDMA data signal at the transmitter using a pseudo random chip code sequence, the spread data signal encompassing the selected range;

the transmitter determining microwave frequencies currently used by the microwave system that have a spectrum overlapping a spectrum of the spread data signal and adaptively notch filtering the spread data signal at the determined microwave frequencies;

transmitting from the transmitter to the receiver the notch filtered spread data signal; and

the receiver recovering data within the notch-filtered CDMA data signal using a replica of the chip code used for generating the spread data signal.

2. The method of claim 1 further comprising detecting a microwave power associated with the overlapping frequencies;

wherein the determining of the overlapping microwave frequencies is based on the detected microwave power.

3. The method of claim 2 wherein the detecting of the microwave power is performed at the receiver.

4. The method of claim 2 wherein the detecting of the microwave power is performed at the transmitter.

5. The method of claim 1 further comprising:

storing the overlapping microwave frequencies at the receiver; and

sending a command to the transmitter, the command indicating the overlapping frequencies; and

wherein the determination of the overlapping frequencies is based on the overlapping frequencies indicated by the command.

6. The method of claim 1 wherein the transmitter is located at a user unit and the receiver is located at a base station.

7. The method of claim 1 wherein each of the overlapping frequencies has an associated bandwidth, the method further comprising determining the bandwidth for each of the overlapping frequencies, wherein the adaptive notch filtering is notch filtering a bandwidth at each of the determined frequencies based on that determined frequency'"'"'s determined bandwidth.

8. A method for communicating in a spread spectrum code division multiple access (CDMA) communication system having a plurality of base stations and a user unit, the CDMA system co-existing with a microwave system, the microwave system assigning differing microwave frequencies to users within a selected range of frequencies to differing geographic regions of the microwave system, the method comprising:

at each said base station, storing the assigned microwave frequencies used in an operating area of that base station;

sending from each of the base stations, a command indicating the assigned microwave frequencies in its operating area;

generating at the user unit a spread-spectrum CDMA data signal using a pseudo random chip code sequence;

receiving the command from the base station in whose operating area the remote unit is located;

adaptively notch filtering the spread data signal at the frequencies indicated by the command;

transmitting from the user unit the notch filtered data signal; and

recovering data within the notch filtered data signal using a replica of the chip code used for generating the spread data signal at the base station whose operating area the remote unit is located.

9. The method of claim 8 further comprising for each of the base stations, storing a bandwidth associated with each of the assigned frequencies in that base station'"'"'s operating area;

wherein the command also indicates the associated stored bandwidths in its operating area and the adaptive notch filtering is notch filtering a bandwidth at each of the assigned frequencies based on that frequency'"'"'s associated bandwidth.

10. A spread spectrum code division multiple access (CDMA) communication system which co-exists with a microwave system, the microwave system selectively utilizing various microwave frequencies within a selected range of frequencies, the CDMA system comprising:

a transmitter comprising;

means for generating a spread spectrum CDMA data signal using a pseudo random chip code sequence, the CDMA signal encompassing the selected range;

means for determining microwave frequencies currently used by the microwave system that have a spectrum overlapping a spectrum of the spread data signal and adaptively notch filtering the spread data signal at the determined microwave frequencies; and

means for transmitting the notch filtered spread data signal to the receiver; and

a receiver comprising;

means for recovering data within the notch filtered data signal using a replica of the chip code used for generating the spread data signal.

11. The CDMA system of claim 10 wherein the transmitter further comprises means for detecting a microwave power associated with the overlapping frequencies;

wherein the determining of the overlapping microwave frequencies is based on the detected microwave power.

12. The CDMA system of claim 10 wherein the receiver further comprises:

means for detecting a microwave power associated with the overlapping frequencies;

wherein the determining of the overlapping microwave frequencies is based on the detected microwave power.

13. The CDMA system of claim 10 wherein the receiver further comprises:

means for storing the overlapping microwave frequencies; and

means for sending a command to the transmitter, the command indicating the overlapping frequencies; and

wherein the determining means determines the overlapping frequencies based on the overlapping frequencies indicated by the command.

14. The CDMA system of claim 10 wherein the transmitter is used by a user unit and the receiver is used by a base station.

15. The CDMA system of claim 10 wherein each of the overlapping frequencies has an associated bandwidth, the transmitter further comprising:

means for determining the bandwidth for each of the overlapping frequencies;

wherein the adaptive notch filtering means notch filters a bandwidth at each of the overlapping frequencies based on that frequency'"'"'s determined bandwidth.

16. A spread spectrum code division multiple access (CDMA) communication system having a plurality of base stations and a user unit, the CDMA system co-exists with a microwave system the microwave system assigning different microwave frequencies to users within a selected range of frequencies to differing geographic regions of the microwave system, the CDMA system comprising:

each of the base stations comprising;

means for storing the assigned microwave frequencies used in an operating area of that base station;

means for sending a command indicating that base station'"'"'s assigned microwave frequencies; and

means for recovering data within a spread spectrum CDMA data signal received from the user unit when the user unit is within that base station'"'"'s operating area using a replica of a pseudo random chip code sequence used for generating the spread data signal; and

the user unit comprising;

means for generating the spread spectrum CDMA data signal using the pseudo random chip code sequence;

means for receiving the command from the base station in whose operating area the remote unit is located;

means for adaptively notch filtering the spread data signal at the frequencies indicated by the command; and

means for transmitting the spread data signal after being notch filtered.

17. The CDMA system of claim 16 wherein said base station further comprises for each of the base station'"'"'s, means for storing a bandwidth associated with each of the assigned frequencies in that base station'"'"'s operating area;

wherein the command also indicates the associated stored bandwidths in its operating area and the adaptive notch filtering means notch filters a bandwidth at each of the assigned frequencies based on that frequency'"'"'s associated bandwidth.

18. A transmitter for use in a spread-spectrum code division multiple access (CDMA) communication system, the CDMA system co-exists with a microwave system selectively utilizing various microwave frequencies within a selected range of frequencies, the transmitter comprising:

a mixer for mixing a data signal with a pseudo random chip code sequence to generate a spread spectrum CDMA data signal, the spread data signal encompassing the selected range of microwave frequencies;

a sensor detecting a microwave power associated with the microwave frequencies that have a spectrum overlapping a spectrum of the spread data signal to determine the overlapping microwave frequencies;

an adaptive notch filter for notch filtering the spread data signal at the determined microwave frequencies; and

an antenna for transmitting to a receiver the notch filtered spread data signal.

19. The transmitter of claim 18 wherein the sensor detects a bandwidth associated with each of the overlapping frequencies and the adaptive notch filter notch filters a bandwidth at each of the determined frequencies based on that determined frequency'"'"'s bandwidth.

20. The transmitter of claim 18 wherein the adjustable notch filter is a tunable notch filter.

21. The transmitter of claim 18 wherein the adjustable notch filter uses variable capacitors to adjust notched frequencies.

22. The transmitter of claim 18 wherein the adaptive notch filter is an adaptive traversal filter.

23. A transmitter for use in a spread-spectrum code division multiple access (CDMA) communication system, the CDMA system co-exists with a microwave system selectively utilizing various microwave frequencies within a selected range of frequencies, the transmitter comprising:

means for generating a spread-spectrum CDMA data signal using a pseudo random chip code sequence, said spread data signal encompassing the selected range;

means for determining microwave frequencies currently used by the microwave system that have a spectrum overlapping a spectrum of the spread data signal and adaptively notch filtering the spread data signal at the determined microwave frequencies; and

transmitting to a receiver the notch filtered spread data signal.

24. The transmitter of claim 23 further comprising means for detecting a microwave power associated with the overlapping frequencies;

wherein the determining means determines the overlapping microwave frequencies based on the detected microwave power.

25. The transmitter of claim 23 wherein each of the overlapping frequencies has an associated bandwidth, the transmitter further comprising:

means for determining the bandwidth for each of the overlapping frequencies;

wherein the adaptive notch filtering means notch filters a bandwidth at each of the determined frequencies based on that frequency'"'"'s determined bandwidth.