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US 6,324,401 B1Granted
Soft handover method used in a CDMA mobile communication system and corresponding device
AssigneeAlcatel
InventorsAlejandro De Hoz Garcia-Bellido, Christopher Cordier
Life of this patent
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Abstract
The invention concerns a method of selecting a base station of a CDMA type network with which a terminal is to perform a soft handover. According to the invention, the base station which requires the lowest transmission power on the part of the terminal is selected.
Claims14
A method, comprising:
- selecting a first base station of a CDMA type network with which a terminal is to perform a soft handover,
- wherein, before selecting said first base station, said first base station is not included in an active set of said terminal;
- and
- wherein said first base station, in order to obtain a required signal-to-interference ratio at said first base station, requires a first transmission power from said terminal that is lower than a respective second transmission power from any second base station that is, before selecting said first base station, included in said active set of said terminal;
- determining a respective third transmission power for each communication with a candidate base station in an uplink direction;
- and
- selecting a third base station for which the respective third transmission power is lower than a threshold value plus a power allocated by said terminal to communication in progress with a fourth base station.
4 more elements
A method of selecting base stations in a CDMA type network with which a terminal is to provide communication simultaneously, said selection being performed according to a criterion, wherein said criterion takes account of a transmission power in an uplink direction, which is required of said terminal in order to obtain a required signal-to-interference ratio at said base stations;
- and wherein the transmission power required of said terminal in the uplink direction is lower than a threshold value plus a power allocated by said terminal to communication in progress with a base station other than said base stations.
A method of selecting base stations in a CDMA type network with which a terminal is to provide communication simultaneously, comprising:
- determining a specific base station of said base stations that benefits from the best propagation conditions in an uplink direction;
- and
- selecting said specific base station to communicate with said terminal, wherein a corresponding transmission power of said terminal required in the uplink direction is lower than a threshold value plus a power allocated by said terminal to communication in progress with a base station other than the specific base station.
A method of managing an active set of a terminal operating in a CDMA type transmission network, comprising:
- determining, for each communication with a respective candidate base station, a respective transmission power required in an uplink direction;
- and
- selecting a first base station for which the respective transmission power required in the uplink direction is lower than a threshold value plus a power allocated by said terminal to communication in progress with a second base station.
A device, comprising:
- a first selection arrangement for selecting a first base station of a CDMA type network with which a terminal is to perform a soft handover,
- wherein, before selecting said first base station, said first base station is not included in an active set of said terminal;
- and
- wherein said first base station, in order to obtain a required signal-to-interference-ratio at said first base station, requires a first transmission power from said terminal that is lower than a respective second transmission power from any second base station that is, before selecting said first base station, included in said active set of said terminal;
- a determination arrangement for determining a respective third transmission power for each communication with a candidate base station in an uplink direction;
- and
- a second selection arrangement for selecting a third base station for which the respective third transmission power is lower than a threshold value plus a power allocated by said terminal to communication in progress with a fourth base station.
4 more elements
A method for performing soft-handover in a CDMA type network, which comprises a plurality of base stations, comprising:
- broadcasting a respective broadcast signal from a respective base station of the plurality of base stations to at least one terminal;
- measuring an intensity of the respective broadcast signal at the terminal;
- determining at least one of a respective target signal-to-interference ratio and a respective target Eb/I ratio required by the respective base station;
- evaluating a respective uplink transmission power level to be transmitted by the terminal to the respective base station to meet the respective target signal-to-interference ratio required by the respective base station, wherein the respective uplink transmission power level depends on the measured intensity of the respective broadcast signal, on a total power received at the respective base station, on a power with which the respective base station broadcasts the respective broadcast signal, and on the at least one of the respective target signal-to-interference ratio and the respective target Eb/I ratio;
- selecting a first base station that is, before selection, not included in an active set of the terminal and that requires a first uplink transmission power level that is lower than a second uplink transmission power level required by any second base station that is, before selecting the first base station, included in the active set of the terminal;
- and
- performing the soft-handover with the first base station.
4 more elements
A device for performing soft-handover in a CDMA type network, wherein the CDMA type network comprises a plurality of base stations, the device comprising:
- a receiver at a terminal to receive an indication relating to an intensity of a respective broadcast signal broadcasted from a respective base station of the plurality of base stations to the terminal;
- a determination arrangement to determine at least one of a respective target signal-to-interference ration and a respective target Eb/I ratio required by the respective base station;
- an evaluation arrangement to evaluate a respective uplink transmission power level to be transmitted by the terminal to the respective base station to meet the respective target signal-to-interference ratio required by the respective base station, wherein the respective uplink transmission power level depends on a measured intensity of the respective broadcast signal, on a total power received at the respective base station, on a power with which the respective base station broadcasts the respective broadcast signal, and on the at least one of the respective target signal-to-interference ratio and the respective target Eb/I ratio;
- a selector to select a first base station that is, before selection, not included in an active set of the terminal and that requires a first uplink transmission power level that is lower than a second uplink transmission power level required by any second base station that is, before selecting the first base station, included in the active set of the terminal;
- and
- an arrangement for performing the soft-handover with the first base station.
3 more elements
Dependencies are inferred from the claim text.