Method of maximizing spectral efficiency in a cellular communications system
First Claim
1. A method of maximizing spectral efficiency in a cellular communications system having a grid of outer cells, a plurality of base stations that generate the grid of outer cells, and at least one network controller connected to the base stations for controlling the system, the method comprising the steps of:
- assigning a first frequency reuse pattern to the grid of outer cells, the first frequency reuse pattern having a first K-value;
generating at least one sub-grid of inner cells within the grid of outer cells, the inner cells being interference-limited by adjacent inner cells within nearby outer cells;
assigning a second frequency reuse pattern to the sub-grid of inner cells, the second frequency reuse pattern having a second K-value that is less than the first K-value;
generating at least one sub-grid of inner--inner cells within the sub-grid of inner cells, the inner--inner cells being interference-limited by adjacent inner--inner cells within nearby inner cells;
assigning a third frequency reuse pattern to the sub-grid of inner--inner cells, the third frequency reuse pattern having a third K-value that is less than the first and second K-values; and
providing a plurality of mobile units having the ability to directly measure the interference level of a serving cell that the mobile is communicating with and at least one neighboring cell.
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Abstract
A system and method for operating a cellular communication system is disclosed wherein frequency reuse of available carrier frequencies is maximized, thereby maximizing system traffic capacity. The invention includes an outer cell grid generated by a plurality of base station transceivers connected to a common network controller. Within the grid of outer cells is at least one overlapping sub-grid of inner cells that may be generated by the same base stations as the outer cells, or which may be generated using separate base station transceivers located within the outer cell. At least two frequency reuse patterns are applied to the cells, one pattern for the outer cells and another, tighter pattern for the inner cells. The inner cells are defined and limited by a predetermined threshold co-channel interference level (C/I), the interference emanating from adjacent inner cells operating at the same frequencies. The invention also includes mobile units that can directly measure both RSSI and C/I of the serving cell and associated neighbor cells. The mobile units take periodic measurement reports which are transmitted to the network when a predetermined threshold interference condition has been met. The network controller than switches the mobile unit to one of the neighbor cells. The present method and system can be used with other traditional techniques for optimizing frequency reuse, such as underlay/overlay or microcellular methods.
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Citations
18 Claims
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1. A method of maximizing spectral efficiency in a cellular communications system having a grid of outer cells, a plurality of base stations that generate the grid of outer cells, and at least one network controller connected to the base stations for controlling the system, the method comprising the steps of:
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assigning a first frequency reuse pattern to the grid of outer cells, the first frequency reuse pattern having a first K-value; generating at least one sub-grid of inner cells within the grid of outer cells, the inner cells being interference-limited by adjacent inner cells within nearby outer cells; assigning a second frequency reuse pattern to the sub-grid of inner cells, the second frequency reuse pattern having a second K-value that is less than the first K-value; generating at least one sub-grid of inner--inner cells within the sub-grid of inner cells, the inner--inner cells being interference-limited by adjacent inner--inner cells within nearby inner cells; assigning a third frequency reuse pattern to the sub-grid of inner--inner cells, the third frequency reuse pattern having a third K-value that is less than the first and second K-values; and providing a plurality of mobile units having the ability to directly measure the interference level of a serving cell that the mobile is communicating with and at least one neighboring cell. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 18)
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16. A method of maximizing spectral efficiency in a cellular communications system having a grid of outer cells, a plurality of base stations that generate the grid of outer cells, and at least one network controller connected to the base stations for controlling the system, the method comprising the steps of:
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assigning a first frequency reuse pattern to the grid of outer cells, the first frequency reuse pattern having a first K-value; generating at least one sub-grid of inner cells within the grid of outer cells, the inner cells being interference-limited by adjacent inner cells within nearby outer cells; assigning a second frequency reuse pattern of the sub-grid of inner cells, the second frequency reuse pattern having a second K-value that is less than the first K-value; and providing a plurality of mobile units having the ability to directly measure the interference level of a serving cell that the mobile is communicating with and at least one neighboring cell; providing a first threshold carrier/interference (C/I) level for switching a mobile unit from an outer cell to an inner cell; the mobile unit reporting (C/I) measurements of a serving outer cell and an included inner cell to the network controller; and the network controller switching the mobile unit to the inner cell of the measured (C/I) level is greater than the first threshold (C/I) level provided. - View Dependent Claims (17)
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Specification