Wireless communication method and system for minimizing interference by determining mobile station zone locations and potential conflicts between cell zones

Abstract

A wireless communication method and system for minimizing severe interference to one or more wireless transmit / receive unit (WTRUs). A plurality of non-overlapping zones (e.g., an inner zone and an outer zone) is defined for each cell of a wireless multi-cell communication system, such as a time division duplex (TDD) system. Information regarding potential conflicts between the non-overlapping cell zones is obtained. Each potential conflict indicates that there is a high likelihood of one of the WTRUs using a specific time slot for transmitting in a zone of one cell causing severe interference to a second one of the WTRUs using the specific time slot for receiving in a zone of another (i.e., a different) cell. Time slot usage (e.g., uplink, downlink or none) is then determined on a zone-by-zone basis using the obtained information to minimize interference caused by a conflicting uplink assignment or a conflicting downlink assignment.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 10 / 334,459 filed Dec. 30,2002, which issued as U.S. Pat. No. 7,046,655 on May 16, 2006, which in turn claims priority from Provisional application No. 60 / 403,685 filed Aug. 15, 2002, which are incorporated by reference as if fully set forth.BACKGROUND OF THE INVENTION [0002] The present invention relates generally to radio communication systems using the time division duplexing (TDD) mode. More particularly, the invention relates to assignment of slots and slot-to-cell assignments in radio communication systems using TDD. [0003] Cellular systems generally divide the time axis into intervals of equal durations called frames. Cellular systems employing the TDD scheme divide frames into a finite number of intervals of equal duration, called slots, and allow a cell to use some or all of the slots for uplink transmissions (mobile-to-base) or downlink (base-to-mobile) tran...

AI Technical Summary

Benefits of technology

The present invention is about a way to reduce interference between wireless devices in a communication system. The invention involves defining non-overlapping zones for each cell in the system and gathering information about potential conflicts between these zones. This information indicates which devices may interfere with each other if they use the same time slot for transmitting or receiving. The invention then determines which devices should use which time slot to minimize interference. The invention also involves tracking the location of devices by determining if they are located in an inner or outer zone of a particular cell. The technical effect of this invention is to improve the reliability and performance of wireless communication systems.

Problems solved by technology

The obvious disadvantage of this approach is when cells are deployed in a way to provide continuous coverage, as is often the case, it is difficult to segregate one subset of cells from another, unless the use of certain slots are completely disallowed in some cells.

This ultimately results in a capacity loss of the system.

Therefore, both mobile-to-mobile and base-to-base interference restrict the use of independent slot assignments between cells in the same geographical area.

Each potential conflict indicates that there is a high likelihood of one of the WTRUs using a specific time slot for transmitting in a zone of one cell causing severe interference to a second one of the WTRUs using the specific time slot for receiving in a zone of another (i.e., a different) cell.

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