Cellular mobile radio system and base transceiver station and base station controller therefor
First Claim
1. A method of selecting a next cell for call handoff of a call already set up between a mobile station in a present cell and a present cell base transceiver station in the present cell, the method comprising:
- determining the distance of the mobile station from the present cell base transceiver station;
when the distance reaches a predetermined threshold;
determining, at the present cell base transceiver station, a first power level of the mobile station received at a first antenna of the present cell base transceiver station, the first antenna being oriented in a first direction,determining, at the present cell base transceiver station, a second power level of the mobile station received at a second antenna of the present cell base transceiver station, the second antenna being oriented in a second direction,selecting a cell adjacent to the present cell as the next cell for handoff based on the first and the second power levels, and on the first and the second directions.
1 Assignment
0 Petitions
Accused Products
Abstract
A cellular mobile radio system selects the best cell to be accessed for a given position of a mobile station by determining the distance of the mobile station relative to the base transceiver station of a cell with which it is communicating by measuring the propagation time between the mobile station and the base transceiver station, resolving the indeterminacy associated with the direction in which said mobile station is located relative to said base transceiver station, and then determining which cell the mobile station is situated in the coverage area of, this cell constituting the best cell. The resolving of the indeterminacy is rendered independent of the synchronized or non-synchronized state of the system.
-
Citations
12 Claims
-
1. A method of selecting a next cell for call handoff of a call already set up between a mobile station in a present cell and a present cell base transceiver station in the present cell, the method comprising:
-
determining the distance of the mobile station from the present cell base transceiver station; when the distance reaches a predetermined threshold; determining, at the present cell base transceiver station, a first power level of the mobile station received at a first antenna of the present cell base transceiver station, the first antenna being oriented in a first direction, determining, at the present cell base transceiver station, a second power level of the mobile station received at a second antenna of the present cell base transceiver station, the second antenna being oriented in a second direction, selecting a cell adjacent to the present cell as the next cell for handoff based on the first and the second power levels, and on the first and the second directions. - View Dependent Claims (7)
-
-
2. A cellular mobile radio system including means for selecting the best cell to be accessed for a given position of a mobile station, said means including:
-
first means for determining the distance of the mobile station relative to the base transceiver station of a cell with which it is communicating by measuring the propagation time between the mobile station and the base transceiver station, second means for resolving the indeterminacy associated with the direction in which said mobile station is located relative to said base transceiver station, and third means for determining, from results provided by said first and second means, in which cell the mobile station is situated, this cell constituting said best cell, wherein said resolving of said indeterminacy is effective even when said base transceiver stations are not in synchronization; wherein at least one cell has no control frequency; and wherein said system is accessed via cells with control frequencies received by the mobile station. - View Dependent Claims (3, 4, 5, 6)
-
-
8. A cellular mobile radio system comprising:
-
a mobile station, a plurality of base transceiver stations associated with respective cells, at least some of said base transceiver stations having corresponding control frequencies, and a controller controlling said base transceiver stations; wherein, when said mobile station requires network access for a call; said mobile station transmits network access request information on one of said received control frequencies to said corresponding one of said plurality of base transceiver stations, said one of said plurality of base transceiver stations defining a first base transceiver station; based on a propagation delay of said network access request information sent to said first base transceiver station, said first base transceiver station determines a first relative distance from said first base transceiver station to said mobile station, and provides said first relative distance to said controller; when said first relative distance indicates that said mobile station is outside said respective cell of said first base transceiver station, said controller commands handover of said call to another of said plurality of base transceiver stations having a corresponding control frequency and defining a second base transceiver station; in response to said command of said controller, said mobile station transmits information to said second base transceiver station; based on a propagation delay of said information sent to said second base transceiver station, said second base transceiver station determines a second relative distance from said second base transceiver station to said mobile station, and provides said second relative distance to said controller; and said controller selects for said call one of said plurality of base transceiver stations defining a selected base transceiver station, based on said first and second relative distances, said associated cell of said selected base transceiver station defining a selected cell. - View Dependent Claims (9)
-
-
10. A method of selecting a next cell for call handoff of a call already set up between a mobile station in a present cell and a present cell base transceiver station in the present cell, the method comprising:
-
determining the distance of the mobile station from the present cell base transceiver station; when the distance reaches a predetermined threshold; determining, at the mobile station, a first power level of a received first control frequency transmitted from a first base transceiver station, determining, at the mobile station, a second power level of a received second control frequency transmitted from a second base transceiver station, and selecting, as the next cell for call handoff, one of a plurality of adjacent cells of the present cell, based on the first power level and the second power level, wherein said one of said plurality of adjacent cells has no control frequency. - View Dependent Claims (11, 12)
-
Specification