Hand-off filter for cellular mobile radio
First Claim
1. In a cellular mobile communication system wherein mobile transceivers can communicate with each other, the system being arranged in a set of cells wherein each cell has a cell station for communication with individual ones of said mobile transceivers, a cluster of said cells having a network station through which said cell stations communicate with each other, said network station operating in conjunction with hand-off apparatus for handing off a transceiver from a first of said cells to a second of said cells as the transceiver travels from the first cell to the second cell;
- the improvement wherein said hand-off apparatus comprises;
means for measuring the strength of a transceiver signal received from one of said mobile transceivers as the transceiver approaches an interface between said first cell and second cell, said measuring means including means for sampling the received signal to provide samples thereof;
means for storing a succession of said samples;
first averaging means coupled to said storing means for providing a short term average of samples in said succession of samples;
second averaging means coupled to said storing means for providing a long term average of samples in said succession of samples;
summing means coupled to said first and said second averaging means for summing a recent sample of said succession with said short term average and said long term average to provide a filtered replica of said received signals; and
means coupled to said summing means for signaling said hand-off apparatus to initiate a hand-off when the amplitude of said filtered replica drops below a predetermined value, said signaling means including means for comparing the amplitude of said filtered replica with a reference signal having said predetermined value.
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Accused Products
Abstract
A cellular mobile radio-telephone system incorporates hand-off equipment for effecting a hand-off of communication links coupled to a mobile subscriber transceiver as the transceiver travels from one cell to an adjoining cell. The hand-off equipment includes a filter which smoothes voice channel signals received from the mobile transceivers so as to permit a more precise determination as to when a reduction in signal amplitude indicates the need for a hand-off. The operation of the filter includes long and short term averaging of a sequence of signal samples. Circuitry is also provided for predicting a time of signal fade-out based on differences in the amplitude of successive samples or groups of samples. Also disclosed is circuitry for commanding a change in transmitter gain in a transceiver as a function of signal fade-out.
102 Citations
14 Claims
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1. In a cellular mobile communication system wherein mobile transceivers can communicate with each other, the system being arranged in a set of cells wherein each cell has a cell station for communication with individual ones of said mobile transceivers, a cluster of said cells having a network station through which said cell stations communicate with each other, said network station operating in conjunction with hand-off apparatus for handing off a transceiver from a first of said cells to a second of said cells as the transceiver travels from the first cell to the second cell;
- the improvement wherein said hand-off apparatus comprises;
means for measuring the strength of a transceiver signal received from one of said mobile transceivers as the transceiver approaches an interface between said first cell and second cell, said measuring means including means for sampling the received signal to provide samples thereof; means for storing a succession of said samples; first averaging means coupled to said storing means for providing a short term average of samples in said succession of samples; second averaging means coupled to said storing means for providing a long term average of samples in said succession of samples; summing means coupled to said first and said second averaging means for summing a recent sample of said succession with said short term average and said long term average to provide a filtered replica of said received signals; and means coupled to said summing means for signaling said hand-off apparatus to initiate a hand-off when the amplitude of said filtered replica drops below a predetermined value, said signaling means including means for comparing the amplitude of said filtered replica with a reference signal having said predetermined value. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- the improvement wherein said hand-off apparatus comprises;
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8. In a cellular mobile communication system wherein mobile transceivers can communicate with each other, the system being arranged in a set of cells wherein each cell has a cell station for communication with individual ones of said mobile transceivers, a cluster of said cells having a network station through which said cell stations communicate with each other, said network station operating in conjunction with hand-off apparatus for handing off a transceiver from a first of said cells to a second of said cells as the tranceiver travels from the first cell to the second cell;
- a method for operation of said hand-off apparatus comprising the steps of;
receiving a transceiver signal repetitively at predetermined instants of time to provide a sequence of samples; filtering the sequence of samples to provide filtered replicas of the transceiver signal;
said filtering including an averaging of signal samples over a first interval of time and over a second interval of time to provide average values of said signal samples, and combining said average values with a recent sample of said sequence;comparing said filtered replicas to a reference; and directing said hand-off apparatus to initiate a hand-off when the magnitude of the filtered replicas drops below the reference. - View Dependent Claims (9, 10, 11, 12, 13, 14)
- a method for operation of said hand-off apparatus comprising the steps of;
Specification