Cellular communications system employing wireless optical links
First Claim
1. A cellular communication system based on a plurality of radio-based communication units, said communication system comprising:
- a central main communication unit;
a primary-cell radio-based communication unit interconnected to said central main unit;
a number of secondary-cell radio-based communication units, each of which is connected to said primary-cell radio-based communication unit via a respective wireless optical link and provided as a remote radio unit forming a distributed radio base station together with said central main unit, said distributed radio base station having radio transceiver functionality divided between said remote secondary-cell radio unit and said central main unit;
means for measuring the quality of at least one of said wireless optical links; and
means for re-directing radio traffic, if the measured wireless optical link quality associated with a secondary-cell communication unit is insufficient, from the secondary-cell communication unit to another one of said communication units within said cellular communication system.
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Abstract
The invention relates to a cellular communication system based on a central main unit, a primary-cell communication unit connected to the central main unit, and a number of secondary-cell communication units. Each secondary-cell unit is connected to the primary-cell unit via a respective wireless optical link. The secondary-cell communication units are preferably remote radio units in a distributed radio base system, where each remote radio unit forms a distributed radio base station together with the central main unit. The wireless optical link quality is measured to detect reduced link availability. The invention compensates for insufficient link availability by providing adequate radio coverage from another communication unit within the cellular system and re-directing the radio traffic to that communication unit. Adequate radio coverage from another communication unit within the cellular system and re-directing the radio traffic to that communication unit. Adequate radio coverage is accomplished either by dynamically increasing the radio coverage or using a micro-macro cell architecture.
33 Citations
23 Claims
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1. A cellular communication system based on a plurality of radio-based communication units, said communication system comprising:
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a central main communication unit;
a primary-cell radio-based communication unit interconnected to said central main unit;
a number of secondary-cell radio-based communication units, each of which is connected to said primary-cell radio-based communication unit via a respective wireless optical link and provided as a remote radio unit forming a distributed radio base station together with said central main unit, said distributed radio base station having radio transceiver functionality divided between said remote secondary-cell radio unit and said central main unit;
means for measuring the quality of at least one of said wireless optical links; and
means for re-directing radio traffic, if the measured wireless optical link quality associated with a secondary-cell communication unit is insufficient, from the secondary-cell communication unit to another one of said communication units within said cellular communication system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of operating a cellular communication system based on a plurality of radio-based communication units, said communication system having a central main communication unit a primary-cell radio-based communication unit interconnected to said central main unit, and a number of associated secondary-cell radio-based communication units, each of which is connected to said primary-cell communication unit via a respective wireless optical link, said method comprising the steps of:
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determining, in a secondary-cell communication unit, a fading rate of a wireless optical signal on the corresponding wireless optical link; and
initiating handover of radio traffic from the secondary-cell communication unit to another radio-based communication unit within said cellular communication system locally in said secondary-cell communication unit or centrally in said central main unit depending on the determined fading rate. - View Dependent Claims (21, 22, 23)
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Specification