Apparatus and method for reducing message collision between mobile stations simultaneously accessing a base station in a CDMA cellular communications system
First Claim
1. A method of reducing message collisions between transmitted messages in a communication network, the method comprising:
- determining whether an access attempt is an access channel request;
performing a persistence test for an access channel slot if the access attempt is an access channel request; and
transmitting a first access probe of an access probe sequence in the slot if the persistence test passes.
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Accused Products
Abstract
Collisions between messages simultaneously transmitted by multiple spread-spectrum transmitters are reduced by distributing the transmissions over the available resources of the receiver. Each mobile station in a CDMA system uses one or more randomization methods to distribute its transmissions. In the first randomization, the mobile station time-delays its transmissions by a number of chips of the PN code with which it spreads the transmitted signal. In a second randomization, the mobile station randomly selects the PN code. In a third randomization, the mobile station inserts a random delay between successive message transmissions or probes if it does not receive an acknowledgement after a predetermined timeout period. A predetermined number of such transmissions is called a probe sequence. In a fourth randomization, the mobile station inserts a relatively long random delay between successive probe sequences if it does not receive an acknowledgement of any probe in the sequence.
16 Citations
24 Claims
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1. A method of reducing message collisions between transmitted messages in a communication network, the method comprising:
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determining whether an access attempt is an access channel request; performing a persistence test for an access channel slot if the access attempt is an access channel request; and transmitting a first access probe of an access probe sequence in the slot if the persistence test passes. - View Dependent Claims (2, 3, 4)
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5. A mobile station apparatus, comprising:
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means for determining whether an access attempt is an access channel request; means for performing a persistence test for an access channel slot if the access attempt is an access channel request; and means for transmitting a first access probe of an access probe sequence in the slot if the persistence test passes. - View Dependent Claims (6, 7, 8)
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9. A computer readable medium embodying a method of reducing message collisions between transmitted messages in a communication network, the method comprising:
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determining whether an access attempt is an access channel request; performing a persistence test for an access channel slot if the access attempt is an access channel request; and transmitting a first access probe of an access probe sequence in the slot if the persistence test passes. - View Dependent Claims (10, 11, 12)
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13. A method for reducing message collisions in a communication network which includes first and second stations, comprising:
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performing an access attempt prior to establishing communication between the first and second stations; characterizing the access attempt from the first station to the second station as an access channel request; characterizing the access attempt from the second station .to the first station as a response channel request; determining whether the access attempt is an access channel request; performing a persistence test on the access channel if the access attempt is the access channel request; transmitting a probe from the first station to the second station through the access channel if the persistence test passes; and forgoing the persistence test on the access channel if the access attempt is the response channel request. - View Dependent Claims (14, 15, 16)
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17. A mobile station apparatus in a communication network for communication with a base station, comprising:
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means for performing an access attempt prior to establishing communication between the mobile station apparatus and the base station; means for characterizing the access attempt from the mobile station apparatus to the base station as an access channel request; means for characterizing the access attempt from the base station to the mobile station apparatus as a response channel request; means for determining whether the access attempt is an access channel request; means for performing a persistence test on the access channel if the access attempt is the access channel request; means for transmitting a probe from the mobile station apparatus to the base station through the access channel if the persistence test passes; and means for forgoing the persistence test on the access channel if the access attempt is the response channel request. - View Dependent Claims (18, 19, 20)
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21. A computer readable medium embodying a method of reducing message collisions between transmitted messages in a communication network which includes first and second stations, the method comprising:
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performing an access attempt prior to establishing communication between the first and second stations; characterizing the access attempt from the first station to the second station as an access channel request; characterizing the access attempt from the second station to the first station as a response channel request; determining whether the access attempt is an access channel request; performing a persistence test on the access channel if the access attempt is the access channel request; transmitting a probe from the first station to the second station through the access channel if the persistence test passes; and forgoing the persistence test on the access channel if the access attempt is the response channel request. - View Dependent Claims (22, 23, 24)
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Specification