Radio telephone system for minimizing co-channel interference ut

Details Radio telephone system for minimizing co-channel interference ut Radio telephone system for minimizing co-channel interference ut

1996-07-02

1998-11-17

Safourek, Benedict V.

Multiplex communications

Communication over free space

Having a plurality of contiguous regions served by...

370341, 370345, 370442, 375202, 379 59, 455 341, 455 383, 455 541, H04B 1713

Patent

active

058386734

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

This invention relates generally to a system for minimizing co-channel interference and more particularly, to a system for minimizing co-channel interference utilizing geographic separation of signals and transmission power control.


BACKGROUND OF THE INVENTION

In general, the purpose of a radio telephone communication system is to transmit information-bearing signals from a source, located at one point to a user destination, located at a point some distance away. A radio telephone communication system generally includes three basic components: transmitter, radio communication channel, and receiver.
In a Frequency Hopping multiple access communications system such as disclosed in co-pending U.S. Pat. application Ser. No. 08/080,075 filed Jun. 1, 1993 and Israeli Patent Application Serial No. 103,620 filed Nov. 3, 1992, a set of N carrier frequencies are reused in adjacent communications sites to provide greater than N minimally cross correlated frequency hopping radio communication channels.
In Time Division Multiplexing ("TDM"), a wideband channel is subdivided into several narrowband channels by allocating the use of the wideband channel to the different narrowband channels during different time slots. Each of these narrowband channels is assigned to different users to allow for contemporaneous utilization of the wideband channel resources by many users.
Time Division Multiple Access ("TDMA") is a technique by which a large population of subscribers with a low individual probability of becoming active get access to the channel resources. This technique relies on a dynamic TDM slot allocation. Similarly, Frequency Division Multiple Access ("FDMA") is an access mechanism for which the underlying multiplexing technique is Frequency Division Multiplexing ("FDM").
It has been proposed that each of the above minimally cross correlated frequency hopping radio communication channels be further divided by time division multiplexing. When high usage of this system occurs substantial co-channel interference is experienced.
PCT patent application, International Publication No. WO 93/10601, published May 27, 1993, discloses a multiple access communications system in which a measure of co-channel interference in a first radio communication channel being used in a first geographic area is determined. The system reacts to the measure exceeding a predetermined level to switch the user to a second radio communication channel in the same geographic area. This system does not address the problem of co-channel interference by minimizing such interference but reacts to the problem after the interference is detected.
It is accordingly an object of the invention to minimize co-channel interference in a multiple access communications system.
It is another object of the invention to minimize co-channel interference in a time division multiple access communications system.
It is still another object of the invention to provide a method of minimizing co-channel interference in such a system by utilizing geographic separation of signals.
It is a further object of the invention to provide a method of minimizing co-channel interference in such a system by utilizing geographic separation of signals and transmission power control.
It is a still further object of the invention to minimize co-channel interference in a time division multiple access communications system which is also frequency hopped.


SUMMARY OF THE INVENTION

The foregoing objects are attained by the invention, which provides a method of and apparatus for minimizing co-channel interference by geographic separation of signals and transmission power control in a combined Frequency Hopping/TDMA radio telephone system. The invention includes a first sector divided into geographic zones, and an adjoining second sector divided into the same number of geographic zones. Time slots are selectively allocated to each of the different geographic zones in the first sector and the same time slots are allocated to the geographic zones in the second sector but

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patent: 4866710 (1989-09-01), Schaeffer
patent: 5287384 (1994-02-01), Avery et al.
patent: 5291475 (1994-03-01), Bruckert
patent: 5301188 (1994-04-01), Kotzin et al.
patent: 5311504 (1994-05-01), Colamonico et al.
patent: 5381443 (1995-01-01), Borth et al.
patent: 5386435 (1995-01-01), Cooper et al.

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