Radio frequency sharing personal communications system

• US 5,448,754 A
• Filed: 01/06/1994
• Issued: 09/05/1995
• Est. Priority Date: 05/07/1993
• Status: Expired due to Fees

• Current Assignee: Corporate Technology Partners
• Original Assignee: Corporate Technology Partners
• Inventors: Ho, C. M. Peter, Lockton, John D.
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): Nguyen, Lee
• Application Number:
  US08/177,912
• Time in Patent Office: 607 Days
• Field of Search: 455/33.1, 455/34.1, 455/34.2, 455/54.1, 455/56.1, 455/62, 455/63, 455/67.1, 455/67.3, 455/226.2, 379/59, 379/60
• US Class Current: 455/454
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04B 17/382 for resource allocation, admission control or handover
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks

Abstract

A radio communications system which is channelized and constituted in cellular array shares the spectrum with other fixed radio communications systems but complies with FCC rules as to interference to these fixed systems. It still maintains however good quality in its signals. Interference is determined by real-time field measurements of interference received from fixed stations on both forward and reverse offset channels by base stations and a mobile terminals. Such real-time measurements besides sensing the quality of a signal can be used to determine interference to the nearby microwave fixed users. In addition compensation is made for multiple users and thus no worst case compromises need be adopted as in prior systems.

Claims

1. A method of determining the availability of wireless communication traffic channels having a quality of transmission suitable for effective communication for use between fixed base stations, having known powers, in a predetermined geographical region and relatively mobile subscriber terminals where said base stations and mobile terminals are linked by forward and reverse frequency channels and where the radio spectrum in which said traffic channels operate must co-exist on a frequency sharing basis with existing fixed radio frequency users, having known powers and operating bandwidths, without interference either to or from said fixed users, the method comprising automatically and dynamically and in a frequency agility manner adjusting to interference to or from said fixed users by selecting and reselecting as necessary traffic channels by the following steps:

measuring interference from said fixed users to said base stations for reverse frequency channels and determining the quality of at least one of said reverse frequency channels;

comparing said determined quality of said at least one of said reverse channels to a predetermined quality threshold to determine if said determined quality is acceptable and said at least one of said reverse channels is usable from a quality standpoint;

determining interference from said base stations to said fixed users on forward frequency channels by using said above measured reverse channel interference, and said known powers of said base stations and said fixed users and said operation bandwidths of said fixed users;

comparing said determined interference on said forward frequency channels to a predetermined interference threshold to determine forward channel usability from an interference standpoint;

measuring interference from said fixed users to a mobile terminal on forward channels and determining the quality of said forward channels;

comparing said determined quality of said forward channels to a predetermined quality threshold to determine if said forward channel quality is acceptable and is usable from a quality standpoint;

determining interference from said mobile terminal to said fixed users on reverse channels by using said above measured forward channel interference;

comparing said determined interference on said reverse channels to a predetermined interference threshold to determine reverse channel usability from an interference standpoint;

assigning said base stations to a forward traffic channel and assigning said mobile terminal to a reverse traffic channel which meet all of said predetermined thresholds;

and continuing to measure interference at said base stations and mobile terminals with the system automatically and dynamically adjusting to changes in interference and quality by moving traffic from existing traffic channels to new traffic channels which meet all of said interference and quality thresholds whenever interference or quality move below predetermined interference and predetermined quality thresholds respectively.

2. A method as in claim 1 wherein said step of determining the quality of the reverse channel includes for a code division multiple access (CDMA) wireless communications system determining a figure of merit based on a ratio of bit energy to noise density.

3. A method as in claim 1, where in said steps of determining interference the same path loss will occur in both directions to and from said fixed users.

4. A method as in claim 1, wherein said mobile terminals have known powers and wherein said step of determining interference from said mobile terminal to said fixed users on said reverse channels, data including the known powers of said mobile terminal and fixed users and the operating bandwidths and frequency of said fixed users are also utilized.

5. A method as in claim i where by utilizing measurement of interference to the forward channels and reverse channels from fixed users it is possible to determine the interference that is being caused by the total system to fixed users.

6. A method of determining the availability of wireless communication traffic channels having a quality of transmission suitable for effective communication for use between a fixed base station, having a known power, in a predetermined geographical region and a relatively mobile subscriber terminal where said base station and mobile terminal are linked by forward and reverse frequency channels and where the radio spectrum in which said traffic channels operation must co-exist on a frequency sharing basis with existing fixed radio frequency users, having known powers and operating bandwidths, without interference either to or from said fixed users, the method comprising automatically and dynamically adjusting to interference to or from said fixed users by selecting said traffic channels by the following steps:

measuring interference from one of said fixed users to said base station for a reverse frequency channel and determining the quality of said reverse frequency channel;

determining interference from said base station to said one of said fixed users on a forward channel by using said above measured reverse channel interference, and said known power of said base station and said one of said fixed users and said operating bandwidths of said one of said fixed users;

comparing said determined interference to a predetermined interference threshold;

measuring interference from said one of said fixed users to said mobile terminal for a forward frequency channel and determining the quality of said forward channel;

determining interference from said mobile terminal to said one of said fixed users on a reverse channel by using said above measured forward channel interference;

comparing said determined interference on said reverse channel to a predetermined interference threshold;

and assigning said mobile terminal to a traffic channel providing interference below all of said predetermined interference thresholds.