Measuring signal strengths of adjacent base stations in a TDMA radio system for a possible handover
First Claim
1. A method for measuring signal strengths of adjacent base stations in a time division multiple access (TDMA) radio system that includes a plurality of mutually adjacent base stations each having at least one transmitter for transmitting a downlink carrier on at least one downlink carrier frequency, said at least one downlink carrier frequency having a cyclically repeating given plurality of successive normal TDMA time slots for conveying control and traffic channels, and a plurality of mobile radio stations capable of registration serially to individual ones of said base stations, and while so registered to any respective one of said base stations being each assigned a respective numbered normal TDMA time slot from among said plurality of normal TDMA time slots, others of said normal TDMA time slots being idle time slots in relation to each said mobile radio station, said method comprising:
- (a) operating at least one of said base stations so as to insert dummy time slots, from time to time, among said normal TDMA time slots being transmitted by the respective transmitter on the respective downlink carrier frequency, according to a set of instances which is not replicated in lockstep by adjacent ones of said base stations, thereby causing a changing temporal offset in occurrence of respectively numbered normal TDMA time slots between said one base station and others of said adjacent base stations;
(b) operating at least one of said mobile stations while registered to a respective said at least one of said base stations, to receive on a respective said downlink carrier frequency during successive ones of said assigned time slots, and to measure signal levels of downlink carrier transmissions from others of said adjacent base stations during non-assigned ones of said time slots.
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Accused Products
Abstract
A method for operating a TDMA system and measuring adjacent base stations in a TDMA radio system in which dummy time slots are inserted into a TDMA signal sent by a base station. These dummy time slots offset the time slots of two carriers with respect to each other. Therefore, a mobile station locked to a predetermined time slot on one carrier is able to measure and decode any time slot of an adjacent carrier within a longer period of time for a possible handover.
33 Citations
12 Claims
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1. A method for measuring signal strengths of adjacent base stations in a time division multiple access (TDMA) radio system that includes a plurality of mutually adjacent base stations each having at least one transmitter for transmitting a downlink carrier on at least one downlink carrier frequency, said at least one downlink carrier frequency having a cyclically repeating given plurality of successive normal TDMA time slots for conveying control and traffic channels, and a plurality of mobile radio stations capable of registration serially to individual ones of said base stations, and while so registered to any respective one of said base stations being each assigned a respective numbered normal TDMA time slot from among said plurality of normal TDMA time slots, others of said normal TDMA time slots being idle time slots in relation to each said mobile radio station, said method comprising:
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(a) operating at least one of said base stations so as to insert dummy time slots, from time to time, among said normal TDMA time slots being transmitted by the respective transmitter on the respective downlink carrier frequency, according to a set of instances which is not replicated in lockstep by adjacent ones of said base stations, thereby causing a changing temporal offset in occurrence of respectively numbered normal TDMA time slots between said one base station and others of said adjacent base stations; (b) operating at least one of said mobile stations while registered to a respective said at least one of said base stations, to receive on a respective said downlink carrier frequency during successive ones of said assigned time slots, and to measure signal levels of downlink carrier transmissions from others of said adjacent base stations during non-assigned ones of said time slots. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A time division multiple access (TDMA) radio system equipped to allow a mobile station thereof to measure signal strengths of base stations adjacent to a base station to which the mobile station is registered,
said TDMA radio system comprising: -
a plurality of mutually adjacent base stations each having at least one transmitter for transmitting a downlink carrier on at least one downlink carrier frequency, said at least one downlink carrier frequency having a cyclically repeating given plurality of successive normal TDMA time slots for conveying control and traffic channels; and a plurality of mobile radio stations capable of registration serially to individual ones of said base stations, and while so registered to any respective one of said base stations being each assigned a respective numbered normal TDMA time slot from among said plurality of normal TDMA time slots, others of said normal TDMA time slots being idle time slots in relation to each said mobile radio station; at least one of said base stations being arranged so as to insert dummy time slots, from time to time, among said normal TDMA time slots being transmitted by the respective transmitter on the respective downlink carrier frequency, according to a set of instances which is not replicated in lockstep by adjacent ones of said base stations, thereby causing a changing temporal offset in occurrence of respectively numbered normal TDMA time slots between said one base station and others of said adjacent base stations; and at least one of said mobile stations while registered to a respective said at least one of said base stations, being arranged to receive on a respective said downlink carrier frequency during successive ones of said assigned time slots and to measure signal levels of downlink carrier transmissions from others of said adjacent base stations during non-assigned ones of said time slots.
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Specification