Spread spectrum CDMA communications system microwave overlay

• US 5,161,168 A
• Filed: 05/15/1991
• Issued: 11/03/1992
• Est. Priority Date: 05/15/1991
• Status: Expired due to Term

• Current Assignee: Interdigital Technology Corporation (InterDigital, Inc.)
• Original Assignee: SCS Mobilecom, Inc (InterDigital, Inc.)
• Inventors: Schilling, Donald L.
• Primary Examiner(s): CANGIALOSI, SALVATORE A
• Application Number:
  US07/700,789
• Time in Patent Office: 538 Days
• Field of Search: 375/1, 380/33, 380/34
• US Class Current: 370/342
• CPC Class Codes: H04J 13/00 Code division multiplex systems for frequency hopping H04B1/713
• CPC Class Codes: H04J 13/0077 Multicode, e.g. multiple codes assigned to one user
• CPC Class Codes: H04L 5/02 Channels characterised by the type of signal
• 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 a plurality of microwave users. The spread spectrum system 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 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, 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 and a transmitter.

Claims

1. A spread spectrum CDMA communications system for communicating data and/or digitized voice between a plurality of personal-communications network (PCN) units, said spread spectrum communications system located within a same geographical region as occupied by a plurality of narrowband microwave users, each of said narrowband microwave users transmitting with a narrowband bandwidth, said spread-spectrum communications systems using spectrum overlaying the narrowband microwave users, said spread spectrum CDMA communications system comprising:

a plurality of PCN-base stations located within the geographical region for communicating data to the plurality of PCN units, each of said PCN-base stations having a cell and including,

base means for converting the format of the data into a form suitable for communicating over radio waves;

base-product means for spread spectrum processing the data with a spread-spectrum bandwidth, the spread-spectrum bandwidth having at least four times any of the narrowband bandwidths of said narrowband microwave users;

base means for transmitting across the spectrum, the spread spectrum processed converted data from the PCN-base station to a PCN unit; and

wherein each of said PCN-base stations is geographically spaced such that power radiated by said base-transmitting means from within its cell to a contiguous cell varies inversely with distance by approximately an exponent of two, and power radiated by said base-transmitting means outside its cell varies inversely with distance by an exponent greater than two;

a plurality of PCN units, each of said PCN units including,

a PCN antenna; and

PCN detection means coupled to said PCN antenna and including PCN-spread-spectrum-processing means, for recovering data communicated from said PCN-base station.

2. The spread spectrum communications system as set forth in claim 1 wherein said PCN detection means includes means for converting the format of the data for output to a user.

3. The spread spectrum communications system as set forth in claim 1 wherein said PCN-spread-spectrum-processing means includes means for storing a local chip code for comparison to signals received for recovering data sent from said PCN-base station to said PCN unit.

4. The spread spectrum communications system as set forth in claim 1 wherein said PCN-spread-spectrum-processing means includes means for synchronizing said PCN-spread-spectrum-processing means to received signals.

5. The spread spectrum communications system as set forth in claim 1 wherein said PCN-spread-spectrum-processing means at said PCN-base station includes means for processing data for particular PCN units with a selected chip code.

12. The spread spectrum communications system as set forth in claim 1 wherein said means for transmitting transmits data in a time division format.

6. A spread spectrum CDMA communications system for communicating data and/or digitized voice between a plurality of personal-communications-network (PCN) units, said spread-spectrum communications system located within a same geographical region as occupied by a plurality of narrowband microwave users, each of said narrowband microwave users transmitting with a narrowband bandwidth, said spread-spectrum communications system using spectrum overlaying the narrowband bandwidths of said plurality of microwave users, said spread spectrum CDMA communications system comprising:

a plurality of PCN units, located within the geographical region as occupied by the plurality of narrowband microwave users for communicating data to a plurality of users, each of said PCN units including,

PCN-product means for spread spectrum processing the data with a spread-spectrum bandwidth, the spread-spectrum bandwidth having at least four times any of the narrowband bandwidths of said narrowband microwave users; and

PCN means for transmitting across the spectrum, the spread spectrum processed converted data from said PCN unit to a PCN-base station;

a PCN-base station located within the cell and including,

a base antenna;

base detection means coupled to said antenna, means, said base-detection means including base-spread-spectrum-processing means, for recovering data communicated from said PCN unit; and

wherein each of said PCN-base stations is geographically spaced such that power radiated by said PCN-transmitting means from within the cell varies inversely with distance by an exponent of approximately two when received at said PCN-base station located within the cell, and that power radiated by a second PCN-transmitting means from outside the cell varies with distance by an exponent greater than two when received at said PCN-base station located within the cell.

7. The spread spectrum communications system as set forth in claim 6 wherein said base detection means includes means for converting the format of the data for output to a user.

8. The spread spectrum communications system as set forth in claim 6 wherein said base-spread-spectrum-processing means includes means for storing a local chip code for comparison to signals received for recovering data sent from said PCN-base station to said PCN unit.

9. The spread spectrum communications system as set forth in claim 6 wherein base-spread-spectrum-processing means includes means for synchronizing said base-spread-spectrum-processing means to received signals.

10. The spread spectrum communications system as set forth in claim 6 wherein said base-spread-spectrum-processing means at said PCN-base station includes means for processing data for particular PCN units with a selected-chip code.

11. The spread spectrum communications system as set forth in claim 6 wherein said means for transmitting transmits data in a time division format.

13. A method for communicating data, including digitized voice signals, between a plurality of PCN units, using a spread spectrum CDMA communications system located within a same geographical region as occupied by a plurality of narrowband microwave users, each of said narrowband microwave users transmitting with a narrowband bandwidth, said spread spectrum CDMA communications system using spectrum overlaying the narrowband bandwidths of said plurality of microwave users, the method comprising the steps of:

geographically spacing a plurality of PCN-base stations such that power radiated by each PCN-base station located within a cell varies inversely with distance by an exponent of approximately two, and such that power radiated by each PCN-base station outside its cell varies inversely with distance by an exponent greater than two;

spread spectrum processing the data with a spread-spectrum bandwidth, the spread-spectrum bandwidth having at least four times any of the narrowband bandwidths of said narrowband microwave users;

transmitting the spread spectrum processed converted data across the spectrum as a spread spectrum signal;

receiving the spread spectrum signal; and

recovering the data from the spread spectrum signal.

14. The method as set forth in claim 13, including the step of converting the format of the recovered data for output to a user.

15. The method as set forth in claim 13, wherein the step of spread spectrum processing the data includes the steps of:

storing a local chip code;

comparing the local chip code to received signals; and

recovering the data from the received signals.

16. The method as set forth in claim 13, wherein the spread spectrum processing of the data step includes synchronizing the spread spectrum processing step to received signals.

17. The method as set forth in claim 13, wherein the step of spread spectrum processing the data includes the step of processing data for particular PCN units with a selected chip code.