Listening control channel in a cellular mobile radiotelephone system
First Claim
1. In a cellular mobile radiotelephone system having at least one microcell and an umbrella cell with a coverage area that mostly or entirely overlaps a coverage area of said microcell and having supervisory means servicing said umbrella cell and said microcell, a call access method comprising the steps of:
- listening for call accesses on a bidirectional control channel of said umbrella cell and unidirectional uplink control channels of said microcells;
communicating information concerning call accesses received by said umbrella cell and said microcell to said supervisory means;
selecting in said supervisory means a cell to handle a call access if a suitable cell is available; and
instructing said umbrella cell to respond to said call access on said bidirectional control channel of said umbrella cell.
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Accused Products
Abstract
A cellular mobile radiotelephone system listens for call accesses on a control channel of an umbrella cell and on a control channel of a microcell located within said umbrella cell and responds to the call access only on the control channel of the umbrella cell. More particularly, the microcells within a particular umbrella cell are provided with listen-only control channel at the same frequency as the uplink control channel of the umbrella cell. An umbrella cell and one or several of its microcells may therefore each receive the same call accesses. During call access, the umbrella cell and each of the microcells determines the strength of the received signal and forwards this information to the system. The system selects the most appropriate cell out of the umbrella cell and the microcells to handle the call and causes the umbrella cell to respond to the call access on its downlink control channel. Among the umbrella cell and its microcells, there are therefore a plurality of uplink control channels, one for each defined cell, and a single downlink control channel, namely that of the umbrella cell. Cell planning remains unchanged as does a directed retry mechanism. Because there is only a single downlink control channel within the coverage area of an umbrella cell, excessive rescanning is avoided. Furthermore, a call is established at the outset in the most appropriate cell, using resources more efficiently and avoiding congestion in the umbrella cell.
57 Citations
16 Claims
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1. In a cellular mobile radiotelephone system having at least one microcell and an umbrella cell with a coverage area that mostly or entirely overlaps a coverage area of said microcell and having supervisory means servicing said umbrella cell and said microcell, a call access method comprising the steps of:
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listening for call accesses on a bidirectional control channel of said umbrella cell and unidirectional uplink control channels of said microcells; communicating information concerning call accesses received by said umbrella cell and said microcell to said supervisory means; selecting in said supervisory means a cell to handle a call access if a suitable cell is available; and instructing said umbrella cell to respond to said call access on said bidirectional control channel of said umbrella cell.
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2. In a cellular mobile radiotelephone system having at least one microcell and an umbrella cell with a coverage area that mostly or entirely overlaps a coverage area of said microcell and having supervisory means servicing said umbrella cell and said microcell, a call access method comprising the steps of:
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listening for call accesses on a bidirectional control channel of said umbrella cell and unidirectional uplink control channels of said microcells; communicating information concerning call accesses received by said umbrella cell and said microcell to said supervisory means;
.selecting in said supervisory means a cell to handle a call access if a suitable cell is available; and instructing said umbrella cell to respond to said call access on said bidirectional control channel of said umbrella cell; during said listening step, measuring signal strength of call accesses received by said umbrella cell and said at least one microcell; and during said communicating step, communicating said signal strengths to said supervisory means. - View Dependent Claims (3, 4, 5, 6, 7, 8)
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9. A cellular mobile radiotelephone system having at least one microcell and an umbrella cell with a coverage area that mostly or entirely overlaps a coverage area of said microcell, comprising:
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means for listening for call accesses on a bidirectional control channel of said umbrella cell and unidirectional uplink control channels of said microcells; supervisory means including means for selecting a cell to handle a call access if a cell is available; means for communicating information concerning call accesses received by said umbrella cell and said microcells to said supervisory means; and means for instructing said umbrella cell to respond to said call access on said bidirectional control channel of said umbrella cell.
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10. A cellular mobile radiotelephone system having a plurality of microcells and an umbrella cell with a coverage area that mostly or entirely overlaps a coverage area of said microcell, comprising:
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means for listening for call accesses on a bidirectional control channel of said umbrella cell and unidirectional uplink control channels of said microcells; supervisory means including means for selecting a cell to handle a call access if a cell is available;
p1 means for communicating information concerning call accesses received by said umbrella cell and said microcells to said supervisory means; andmeans for instructing said umbrella cell to respond to said call access on said bidirectional control channel of said umbrella cell; means for measuring signal strength of call accesses received by said umbrella cell and said microcell; wherein said means for communicating includes means for communicating said signal strengths to said supervisory means. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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Specification