Random access in mobile radio telephone systems
First Claim
1. A method for minimizing co-channel interference caused by radio communications initiated between at least one of a plurality of first radio stations and a second radio station, comprising the steps of:
- communicating from said at least one of a plurality of first of radio stations to said second radio station using the same radio frequency subject to co-channel interference;
transmitting from said at least one first radio station an access message at a relatively low power level;
determining whether said access message has been detected by said second radio station;
retransmitting said access message at an increased power level until said access message is detected; and
upon detecting said access message, transmitting power setting information including a specific power increase quantity for said first station from said second station.
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Accused Products
Abstract
The present invention includes a system and method for minimizing interference between two radio stations, e.g., a mobile radio telephone and a fixed base station, at the initiation of a radio communication. A mobile station initiates a random access at the lowest power level and increases the transmission power level until the base station detects the access signal. Once detected, the power level of the message is maintained at the detected level so that the signal interference is avoided. The present invention also provides a mechanism for synchronizing random access communications between mobile stations and the base station despite variation in distances between the mobile and base stations.
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Citations
43 Claims
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1. A method for minimizing co-channel interference caused by radio communications initiated between at least one of a plurality of first radio stations and a second radio station, comprising the steps of:
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communicating from said at least one of a plurality of first of radio stations to said second radio station using the same radio frequency subject to co-channel interference; transmitting from said at least one first radio station an access message at a relatively low power level; determining whether said access message has been detected by said second radio station; retransmitting said access message at an increased power level until said access message is detected; and upon detecting said access message, transmitting power setting information including a specific power increase quantity for said first station from said second station. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A mobile radio station for communicating with at least one other radio station, comprising:
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communicating from said mobile radio station to said at least one other radio station using the same radio frequency subject to co-channel interference; means for transmitting from said mobile radio station to said at least one other radio station a random access message at a relatively low power level; means for detecting an reply message from said at least one other radio station; and means for commanding said transmitting means to retransmit said random access message at an increased power level if said reply message has not been detected to include an acknowledgement supplying power setting information comprising a specific power increase quantity. - View Dependent Claims (16, 17, 18)
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19. A communications system with minimized co-channel interference, comprising:
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plural mobile radiotelephone stations, each mobile station including; means for transmitting an access message initially at a relatively low power level; means for regulating the power level of said transmitting means; and control means for controlling said regulating means depending on whether said access message has been detected; at least one base station including; means for receiving a composite of overlapping signals transmitted from said mobile stations on the same frequency channel subject to co-channel interference; means for detecting said access messages; and means for transmitting a reply message including power setting information comprising a specific power increase quantity to the mobile station corresponding to said detected access message. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A method for establishing radio communications between at least one of a plurality of first radio stations and at least one second radio station, comprising the steps of:
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selecting, by one of said first stations, a lightly loaded channel subject to co-channel interference of said at least one of said second stations; and
,following a random access procedure including selecting, by said first station, a scrambling code identified from a list of codes broadcast by said second station; transmitting, by said first station, a call initiation message including said selected code at a relatively low power level; and gradually increasing, by said first station, said power level of said transmitted message until an acknowledgement message is received from said second station, said acknowledgement message including a specific power increase quantity. - View Dependent Claims (34, 35, 36, 37, 38, 39, 40, 41)
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42. A method for minimizing interference caused by termination of radio communications between a first radio station and a second radio station, comprising the steps of:
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entering a call termination mode after a last communication segment; gradually diminishing a transmission power level; and terminating transmission when said power level has diminished by a predetermined extent. - View Dependent Claims (43)
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Specification