Handoff apparatus and method with interference reduction for a radio system
First Claim
1. A method of interference reduction in a multichannel two way radio system having at least two geographic radio coverage areas established by a fixed site apparatus in each coverage area and a plurality of remote stations, each remote station capable of transmitting at one of a plurality of power levels and capable of being handed off from one coverage area to another, comprising the steps of:
- calculating a power level for a remote station transmitting to fixed site apparatus in a first coverage area which will produce a received signal level of a predetermined magnitude at fixed site apparatus in a second coverage area; and
communicating said power level to said transmitting remote station during a handoff of said transmitting remote station from said first coverage area to said second coverage area.
1 Assignment
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Accused Products
Abstract
A two way radio system employing power control of a remote station transmitter to produce a predetermined received signal level at a fixed site after handoff of the remote station from one radio channel to another is disclosed. A signal strength measurement is made on the in-use channel and a power level for the remote station transmitter is calculated from the measured signal strength, a predetermined nominal signal strength desired on the target radio channel, and a linear correlation of signal strength and remote station power level steps. The calculated remote station power level is then transmitted to the remote station as part of a handoff command.
111 Citations
25 Claims
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1. A method of interference reduction in a multichannel two way radio system having at least two geographic radio coverage areas established by a fixed site apparatus in each coverage area and a plurality of remote stations, each remote station capable of transmitting at one of a plurality of power levels and capable of being handed off from one coverage area to another, comprising the steps of:
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calculating a power level for a remote station transmitting to fixed site apparatus in a first coverage area which will produce a received signal level of a predetermined magnitude at fixed site apparatus in a second coverage area; and communicating said power level to said transmitting remote station during a handoff of said transmitting remote station from said first coverage area to said second coverage area. - View Dependent Claims (2, 3, 4)
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5. A method of remote station handoff from transmission and reception on a first radio channel to transmission and reception on a second radio channel of a two way radio system having at least two radio channels and a plurality of remote stations, each remote station being able to transmit at one of a plurality of power levels determined by a current power level increment signal, the method comprising the steps of:
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measuring a received signal strength resulting from transmission by an active remote station on the first radio channel; calculating a remainder signal strength from said measured received signal strength and a predetermined nominal signal strength; transforming said remainder signal strength into a relative power level increment signal; calculating a handoff power level increment signal from said relative power level increment signal and the current power level increment signal; and conveying said handoff power level increment signal and a handoff command to said active remote station. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
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14. A two way radio system having at least two radio channels and the capability of handing off an active one of a plurality of remote stations from transmission and reception on a first radio channel to transmission and reception on a second radio channel, the active one remote station transmitting at one of a plurality of power levels determined by a current power level increment signal, the system comprising:
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means for measuring received signal strength resulting from transmission by the active one remote station on the first radio channel; means for calculating a remainder signal strength from said measured received signal strength and a predetermined nominal signal strength; means for transforming said remainder signal strength into a relative power level increment signal; means for calculating a handoff power level increment signal from said relative power level increment signal and the current power level increment signal; and means for conveying said handoff power level increment signal and a handoff command to the active one remote station on the first radio channel. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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23. A base site controller for a cellular radiotelephone system which reduces co-channel and adjacent channel interference after handoff of remote transceivers, said remote transceivers transmitting at one of a plurality of power levels determined by a current power level increment signal, the base site controller comprising:
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means for measuring received signal strength resulting from remote transceiver transmission on a first radio channel; means for calculating a remainder signal strength by subtracting a predetermined nominal signal strength from said measured received signal strength; means for transforming said remainder signal strength into a relative power level increment signal; and means for calculating a handoff power level increment signal, which determines the power level of the remote transceiver when handed off to a second radio channel, by adding said relative power level increment signal to the current power level increment signal. - View Dependent Claims (24, 25)
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Specification