Location determination and handover in mobile radio systems
AssigneeBritish Telecommunications public limited company
InventorSi T. S. Chia
Life of this patent
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Abstract
A handover initiation system for a cellular radio network comprises means for determining both the distance of a mobile user from a cell base station based on propagation delay techniques and means for measuring the signal strength to determine the path taken by the mobile user. In a busy area microcells are constituted by single streets. The propagation characteristics of adjoining streets in a larger macrocell can be distinguished from the propagation characteristics of the street constituting the micro-cell such that the handover initiation of a mobile user within one of the surrounding streets can be determined.
Claims20
A system for determining the location of a mobile unit in a micro-cellular radio network having a plurality of base stations each providing radio coverage over a respective micro-cell and able to communicate with mobile units within the respective micro-cell, the system comprising:
- means for storing with respect to each of one or more locations a corresponding order pair of measured distance and measured signal characteristic associated with that location;
- means for forming a current order pair for a mobile unit including means for determining a current distance of a mobile unit from a base station and means for measuring a current characteristic of a radio signal transmitted between a mobile unit and a base station;
- and
- means for comparing a stored order pair with a current order pair for the mobile unit to determine the current location of the mobile unit.
A base station for a mobile radio network including:
- receiving means for receiving a signal;
- control means for controlling calls to and from mobile units;
- means for determining the distance of the mobile unit from the base station;
- means for storing a set of signal characteristics of at least one possible mobile unit path in the area around the base station, each constituent of the set being associated with a location on the path;
- means for determining the presence of a constituent of the set of signal characteristics in the received signal;
- means for combining the determined distance with the presence of said constituent to identify the location of the mobile unit on a particular path based on the stored set;
- and
- means for initiating a handover from one base station to another base station on the basis of the identified location.
A method for determining the location of a mobile unit in a micro-cellular radio network having a plurality of base stations each providing radio coverage over a respective micro-cell and able to communicate with mobile units within the respective micro-cell, the method comprising:
- storing with respect to each of one or more locations a corresponding order pair of measured distance and measured signal characteristic associated with that location;
- forming a current order pair for a mobile unit by determining a current distance of a mobile unit from a base station and measuring a current characteristic of a radio signal transmitted between a mobile unit and a base station;
- and
- comparing a stored order pair with a current order pair for the mobile unit to determine the current location of the mobile unit.
A method for determining the location of a mobile radio transceiver with respect to a fixed base station radio transceiver in a cellular radio-telephone network, said method comprising the steps of:
- measuring the relative signal propagation time between said mobile and fixed base radio transceivers;
- measuring a further signal characteristic for signals propagated between said mobile and fixed base radio transceivers;
- and
- processing said measured signal propagation time and said measured further signal characteristic with predetermined and pre-stored data to determine the location of the mobile radio transceiver.
Dependencies are inferred from the claim text.