Criteria for base station selection, including handover, in a wireless communication system
First Claim
1. A method for selecting a base station comprising:
- receiving transmissions from a plurality of base stations;
deriving from the transmissions indications of received signal strength associated with each of the plurality of base stations;
ordering a set of candidate base stations in accordance with descending indications of received signal strength;
deriving from the transmissions load information associated with each of the plurality of base stations;
comparing load information between a likely selected base station and the remaining set of candidate base stations;
deriving from the transmissions distance information associated with each of the plurality of base stations;
comparing distance information between the likely selected base station and the remaining set of candidate base stations;
selecting one of the plurality of base stations as a current base station when the load of and distance to the likely selected base station does not exceed the load of and distance to each of the remaining set of candidate base stations by a first threshold; and
selecting an alternative base station when the load of and distance to the likely selected base station exceeds the load of and distance to an alternative base station of the remaining set of candidate base stations by the first threshold.
4 Assignments
0 Petitions
Accused Products
Abstract
The present invention provides method and apparatus for facilitating base station selection/handover by a user terminal in a distributed (e.g., cellular-type) wireless communication system. In accordance with one aspect, hysteresis is adaptively determined as a function of the variance of receive signal strength fluctuations. In turn, an adaptive hysteresis factor can be obtained and used for a subsequent handover decision, for example, based on a cost function that takes into account the hysteresis. In accordance with another aspect, base station selection depends on a number of criteria, such as received signal strength, base station load, and estimated distance between a receiving user terminal and one or more base stations.
-
Citations
22 Claims
-
1. A method for selecting a base station comprising:
-
receiving transmissions from a plurality of base stations;
deriving from the transmissions indications of received signal strength associated with each of the plurality of base stations;
ordering a set of candidate base stations in accordance with descending indications of received signal strength;
deriving from the transmissions load information associated with each of the plurality of base stations;
comparing load information between a likely selected base station and the remaining set of candidate base stations;
deriving from the transmissions distance information associated with each of the plurality of base stations;
comparing distance information between the likely selected base station and the remaining set of candidate base stations;
selecting one of the plurality of base stations as a current base station when the load of and distance to the likely selected base station does not exceed the load of and distance to each of the remaining set of candidate base stations by a first threshold; and
selecting an alternative base station when the load of and distance to the likely selected base station exceeds the load of and distance to an alternative base station of the remaining set of candidate base stations by the first threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A machine-readable medium having stored thereon a set of machine-executable instructions that, when executed by a data-processing system, cause the system to perform a method for selecting a base station comprising:
-
receiving transmissions from a plurality of base stations;
deriving from the transmissions indications of received signal strength associated with each of the plurality of base stations;
ordering a set of candidate base stations in accordance with descending indications of received signal strength;
deriving from the transmissions load information associated with each of the plurality of base stations;
comparing load information between a likely selected base station and the remaining set of candidate base stations;
deriving from the transmissions distance information associated with each of the plurality of base stations;
comparing distance information between the likely selected base station and the remaining set of candidate base stations;
selecting one of the plurality of base stations as a current base station when the load of and distance to the likely selected base station does not exceed the load of and distance to each of a the remaining set of candidate base stations by a first threshold; and
selecting an alternative base station when the load of and distance to the likely selected base station exceeds the load of and distance to an alternative base station of the remaining set of candidate base stations by the first threshold. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
-
-
19. A user terminal comprising:
-
a receiver to receive transmissions from a plurality of base stations;
a receive signal strength measurement unit to derive indications of received signal strength for each of the transmissions;
a distance calculation unit to derive from the transmissions distance information associated with each of the plurality of base stations; and
a base station selection unit to;
order a set of candidate base stations in accordance with descending indications of received signal strength, to derive from the transmissions load information associated with each of the plurality of base stations;
compare load information between a likely selected base station and the remaining set of candidate base stations;
compare distance information between the likely selected base station and the remaining set of candidate base stations;
select one of the plurality of base stations as a current base station when the load of and distance to the likely selected base station does not exceed the load of and distance to each of the remaining set of candidate base stations by a first threshold; and
select an alternative base station when the load of and distance to the likely selected base station exceeds the load of and distance to an alternative base station of the remaining set of candidate base stations by the first threshold. - View Dependent Claims (20, 21, 22)
-
Specification