Soft hand-off in cellular mobile communications networks
AssigneeFujitsu Limited
InventorBehzad Mohebbi
Life of this patent
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Abstract
In a cellular mobile communications network a mobile station is capable of receiving a downlink signal from each of a plurality of base stations and transmitting an uplink signal to the plurality of the base stations through a wireless channel. The mobile station produces a measure of signal quality of the downlink signals from the plurality of base stations to the mobile station and selects a base station from which the downlink signal shows a preferred signal quality. The mobile station transmits an uplink signal indicating the selected base station among the plurality of base stations for subsequent communications with the mobile station. Each base station processes the uplink signal to identify the selected base station from among the plurality of base stations.
Claims33
A cellular mobile communications network in which a mobile station is capable of receiving a downlink signal from a plurality of base stations in a soft hand-off mode with the mobile station and transmitting an uplink signal to the plurality of the base stations through a wireless channel, comprising:
- a selection means for producing a measure of signal quality of the downlink signals from the plurality of base stations in said soft hand-off mode with the mobile station every receiving predetermined period and for selecting a base station from which the downlink signal shows a preferred signal quality;
- a transmission means for transmitting the uplink signal indicating the selected base station among the plurality of base stations for subsequent communication with the mobile station every transmitting predetermined period;
- and
- a processing means for processing the uplink signal to identify the selected base station, from among the plurality of base stations in said soft hand-off mode,
- wherein said mobile station, while in said soft handoff mode, periodically re-selecting a base station from which the downlink signal shows the preferred signal quality and transmitting the uplink signal including the identification of the selected base station, among the plurality of base stations in said soft hand-off mode.
A cellular mobile communications network, comprising:
- a plurality of base stations, in a soft hand-off mode with the mobile station, each being capable of transmitting a downlink signal to a mobile station and receiving an uplink signal from the mobile station through a wireless channel, each base station including:
- a processing unit for identifying a selected base station among the plurality of base stations upon receiving from the mobile station an uplink signal indicating the selected base station from which the downlink signal shows a preferred signal quality every receiving predetermined period;
- the network further comprising a base station controller connected to the plurality of base stations for delivering the downlink signals thereto for further transmission by said base stations,
- wherein when said base station is the selected base station, said base station transmits the next downlink signal, otherwise said base station maintains the soft handoff mode with the mobile station without sending the next downlink signal.
A cellular mobile communications network, comprising:
- a plurality of base stations, in a soft hand-off mode with the mobile station, each of which is capable of transmitting a downlink signal to a mobile station and receiving an uplink signal from the mobile station through a wireless channel, each base station including:
- a processing unit for identifying a selected base station every receiving predetermined period, among the plurality of base stations upon receiving from the mobile station the uplink signal indicating the selected base station, for subsequent communication with the mobile station, from which the downlink signal shows a preferred signal quality,
- wherein when said base station is the selected base station, said base station transmits the next downlink signal, otherwise said base station maintains the soft handoff mode with the mobile station without sending the next downlink signal.
A method for a cellular mobile communications network, comprising the steps of:
- receiving a downlink signal from each of a plurality of base stations in a soft hand-off mode with a mobile station through a wireless channel;
- measuring a signal quality of the downlink signals received from the plurality of base stations every receiving predetermined period;
- selecting, in dependence upon the measured signal quality, a base station for subsequent communication with a mobile station;
- and
- transmitting an uplink signal, to the plurality of base stations through the wireless channels, indicating the selected base station among the plurality of base stations every transmitting predetermined period,
- wherein said mobile station, while in said soft handoff mode, periodically re-selecting a base station from which the downlink signal shows the preferred signal quality and transmitting the uplink signal including the identification of the selected base station, among the plurality of base stations in said soft hand-off mode.
A method for a cellular mobile communications network in which a mobile station is capable of receiving a downlink signal from each of a plurality of base stations in a soft hand-off mode with the mobile station and transmitting an uplink signal to the plurality of base stations through a wireless channel, comprising the steps of:
- receiving, from the mobile station, an uplink signal indicating a selected base station from which the downlink signal shows a preferred signal quality every receiving predetermined period;
- and
- identifying the selected base station every receiving predetermined period, among the plurality of base stations in said soft hand-off mode, for subsequent communication with the mobile station,
- wherein when said base station is the selected base station, said base station transmits the next downlink signal, otherwise said base station maintains the soft handoff mode with the mobile station without sending the next downlink signal.
A cellular mobile communications network wherein
- a mobile station is capable of receiving a downlink signal from each of a plurality of base stations in a soft hand-off mode with the mobile station and transmitting an uplink signal to the plurality of the base stations through a wireless channel,
- the mobile station produces a measure of a signal quality of the downlink signals received from the plurality of base stations every receiving predetermined period, and transmits an uplink signal indicating a selected base station for subsequent communication with the mobile station every transmitting predetermined period, said selected base station based on the measure of the signal quality of the downlink signal, and
- each of the plurality of base stations receives, from the mobile station, the uplink signal, and identifies if each of the plurality of base stations is the selected base station every receiving predetermined period, and when said base station is the selected base station, said base station transmits the next downlink signal, otherwise said base station maintains the soft handoff mode with the mobile station without sending the next downlink signal.
A cellular mobile communication network having a plurality of base stations, and a mobile station capable of receiving a downlink signal from each of said plurality of base stations in a soft hand-off mode with the mobile station and transmitting an uplink signal to the plurality of base stations, said cellular mobile communications network comprising:
- a processor which monitors a predetermined signal characteristic of each downlink signal received at said mobile station and compares predetermined signal characteristic of said downlink signals and selects a preferred base station from among said plurality of base stations in the soft hand-off mode with the mobile station every receiving predetermined period, said processor including:
- a message generator which generates a base station selection message which identifies the selected preferred base station;
- a transmitter which transmits the base station selection message in the uplink signal every transmitting predetermined period;
- and
- a controller for providing an identification to each base station in a soft hand-off mode with the mobile station,
- wherein said mobile station, while in said soft handoff mode, periodically re-selecting a base station from which the downlink signal shows the preferred signal quality and transmitting the uplink signal including the identification of the selected base station, among the plurality of base stations in said soft hand-off mode.
A cellular mobile communications network, comprising:
- a plurality of base stations each being capable of transmitting a downlink signal to a mobile station and receiving an uplink signal from the mobile station through a wireless channel, each base station including:
- a soft hand-off control unit for processing the uplink signal and determining from the uplink signal an identification of a preferred base station from among the plurality of base stations participating in a soft hand-off mode with the mobile station every receiving predetermined period;
- and
- a mobile station for receiving the downlink signal from each of said plurality of base stations in a soft hand-off mode with the mobile station and transmitting the uplink signal to said plurality of base stations, said mobile station including:
- a controller for providing an identification to each base station involved in the soft hand-off mode with the mobile station every transmitting predetermined period,
- wherein said mobile station, while in said soft handoff mode, periodically re-selecting a base station from which the downlink signal shows the preferred signal quality and transmitting the uplink signal including the identification of the selected base station, among the plurality of base stations in said soft hand-off mode.
A cellular mobile communications network in which a mobile station is capable of receiving a downlink signal from each of a set of base stations in a soft hand-off mode with the mobile station and transmitting an uplink signal to the set of base stations through a wireless channel, comprising:
- a selection means for producing a measure of signal quality of the downlink signals from the set of base stations in said soft hand-off mode with the mobile station and for selecting a base station from which the downlink signal shows a preferred signal quality;
- a transmission means for transmitting the uplink signal including an identification of the selected base station among the set of base stations in a soft hand-off mode;
- and
- a processing means for processing the uplink signal to identify the selected base station, from among the set of base stations in said soft hand-off mode,
- wherein said selected base station actively transmits the subsequent downlink signal to the mobile station while the non-selected base stations continue in said soft hand-off mode without transmitting to the mobile station, and
- wherein said mobile station, while in said soft handoff mode, periodically re-selecting a base station from which the downlink signal shows the preferred signal quality and transmitting the uplink signal including the identification of the selected base station, among the plurality of base stations in said soft hand-off mode.
Dependencies are inferred from the claim text.