BEAM WOBBLING FOR INCREASED DOWNLINK COVERAGE AND CAPACITY

• US 20070142045A1
• Filed: 02/27/2007
• Published: 06/21/2007
• Est. Priority Date: 09/30/2003
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: PERIYALWAR, Shalini, MATYAS, Robert, SENARATH, Nimal, CHEONG, Yoon Chae
• Granted Patent: US 8,068,876 B2
• Time in Patent Office: Days
• US Class Current: 455/422.100
• CPC Class Codes: H04B 7/0604 with predefined switching scheme
• CPC Class Codes: H04B 7/0695 using beam selection
• CPC Class Codes: H04W 16/02 Resource partitioning among network components, e.g. reuse partitioning
• CPC Class Codes: H04W 16/12 Fixed resource partitioning
• CPC Class Codes: H04W 16/28 using beam steering

Abstract

A method and apparatus for reducing signal interference within a cellular radio system to increase both coverage and capacity. The method and apparatus include altering the direction of beams within cell sectors is among discrete angular positions according to a predetermined, cyclic pattern. The predetermined, cyclic pattern varies in a group of adjacent cell sectors such that inter-cell interference is significantly reduced or eliminated by rotating at a different cycle the beams in adjacent cells. This discrete, angular movement of beams provides for downlink transmissions to be timed in such a way (i.e., scheduled) such that transmission to a user will occur in accordance with the beam and time slot having the best carrier to interference (C/I) ratio for that user.

Claims

1. A method for reducing interference between adjacent cells of a cellular radio system, comprising:

(a) in a cell of said cellular radio system, transmitting traffic along a downlink beam to a first user terminal during a first time slot;

(b) rotating said downlink beam by a predetermined angle;

(c) transmitting along said downlink beam to a further user terminal during a second time slot; and

(d) repeating steps (a), (b), and (c) until the entire area of cell is covered;

said predetermined angle being varied in accordance with a predetermined pattern.

2. The method of claim 1, wherein said predetermined angle is a part of the width of said downlink beam.

3. The method of claim 1, wherein said steps (a) through (d) are performed in a cyclic manner.

4. A method for controlling interference between first and second traffic carrying beams of adjacent cells of a cellular radio system, said method comprising:

(a) rotating a first beam along a plurality of successive orientations according to a first rotation scheme;

(b) rotating a second beam along a plurality of successive orientations according to a second rotation scheme;

(c) identifying different timeslots with varying quality created by said first and second rotation schemes; and

(d) selecting a reception timeslot from said different timeslots that corresponds to an optimal C/I ratio for user equipment residing within a location covered by both said first and second beams.

5. The method of claim 4, wherein steps (c) and (d) include using orthogonal cyclic patterns for said first rotation scheme and said second rotation scheme.