EP0406186A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Mobile assisted handoff
Assignee: Telefonaktiebolaget LM Ericsson AB
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Filing: 1990-05-17
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Granted: —
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Expires: 2010-05-17
Abstract
Abstract The invention relates to a method for communication and handoff in a cellular mobile radio system and a base station and a mobile station for communication and handoff in such a system, in which time slot identifier codes are transmitted in bursts in times slots in frames of radio channels used for time division communication channels, the time slot identifier codes being indicative of burst time slot in a frame but not of transmitter or receiver entity or radio channel, the time slot identifier codes being used for burst synchronization and determining bursts the signal strength of which to be measured for the purpose of possible handoff.
Inventors
- 👤 Jan Erik Ake Steinar Dahlin
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 07:05
CPC Classifications
H; H04; H04W; H04W36/00; H04W36/0005; H04W36/0055; H04W36/0072; H04L; H04L1/00; H04L1/20; H04L1/208; H04L25/00; H04L25/02; H04L25/0202; H04L25/0212; H04L25/0216; H04W24/00; H04W24/10; H04W36/0066; H04W36/0083; H04W36/0085; H04W36/0088; H04W36/08; H04W36/24; H04W36/30
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
593 words
A method of communication and handoff in a cellular mobile radio system comprising base stations, mobile stations and a plurality of radio channels, at least two of the radio channels being used for time divisional multiplexed digital communication channels, the method comprising the steps of: transmitting to a particular mobile station from a base station responsible for the communication with the particular mobile station at setup of a connection on a digital communication channel and at handoff of a connection to a digital communication channel, information identifying a particular time slot identifier code, a particular digital voice colour code and a plurality of selected radio channels; transmitting from the particular mobile station the particular time slot identifier and digital voice colour codes with radio signals in each time slot of the digital communication channel of the connection during the course of the connection; measuring at the particular mobile station the strength of radio signals received on the selected radio channels and the signal strength on the digital communication channel used for the connection of the mobile station; transmitting repeatedly from the particular mobile station to the responsible base station results of measurements of signal strength at the particular mobile station; processing and analyzing results of measurements done and comparing with criteria for handoff; determining a target base station assumed suitable for being responsible for the communication with the particular mobile station when, according to the processing and analyzing and comparing, a handoff ought to be done; supplying the target base station with information identifying radio channel, the particular time slot identifier code and the particular digital voice colour code of the digital communication channel of the established connection of the particular mobile station; using the supplied information on radio channel and particular time slot identifier code at the target base station for finding the digital communication channel of the established connection of the particular mobile station and checking the appearence of the particular digital voice colour code; reporting from the target base station the results of the checking of the appearence of the particular digital voice colour code on the digital communication channel of the established connection; deciding whether the handoff shall be performed in view of the report from the target base station and informing the target base station and the particular mobile station if the handoff shall be performed; informing the mobile station on the new radio channels, new time slot identifier and digital voice colour codes to be used by the particular mobile station and target base station for the established connection after handoff; at least after receiving at the target base station information that a handoff shall be performed, transmitting from the target base station radio signals comprising the new time slot identifier code on the radio channel to be used by the target base station for the connection after handoff; after receiving at the particular mobile station information that handoff shall be performed, using the new time slot identifier code at the mobile station to find the correct time slot and transmitting from the particular mobile station radio signals comprising the new time slot identifier code and digital voice colour code on the new radio channel; and after receiving at the target base station information that a handoff shall be performed and information on new radio channel and time slot identifier code to be used by the particular mobile station, checking at the target base station the appearence of radio signals comprising both the time slot identifier code and the digital voice colour code on the radio channel.
Claim 2
Independent Claim
593 words
A method of communication and handoff in a cellular mobile radio system comprising base stations, mobile stations and a plurality of radio channels, at least two of the radio channels being used for time divisional multiplexed digital communication channels, the method comprising the steps of: transmitting to a particular mobile station from a base station responsible for the communication with the particular mobile station at setup of a connection on a digital communication channel and at handoff of a connection to a digital communication channel, information identifying a particular time slot identifier code, a particular digital voice colour code and a plurality of selected radio channels; transmitting from the particular mobile station the particular time slot identifier and digital voice colour codes with radio signals in each time slot of the digital communication channel of the connection during the course of the connection; measuring at the particular mobile station the strength of radio signals received on the selected radio channels and the signal strength on the digital communication channel used for the connection of the mobile station; transmitting repeatedly from the particular mobile station to the responsible base station results of measurements of signal strength at the particular mobile station; processing and analyzing results of measurements done and comparing with criteria for handoff; determining a target base station assumed suitable for being responsible for the communication with the particular mobile station when, according to the processing and analyzing and comparing, a handoff ought to be done; supplying the target base station with information identifying radio channel, the particular time slot identifier code and the particular digital voice colour code of the digital communication channel of the established connection of the particular mobile station; using the supplied information on radio channel and particular time slot identifier code at the target base station for finding the digital communication channel of the established connection of the particular mobile station and checking the appearence of the particular digital voice colour code; reporting from the target base station the results of the checking of the appearence of the particular digital voice colour code on the digital communication channel of the established connection; deciding whether the handoff shall be performed in view of the report from the target base station and informing the target base station and the particular mobile station if the handoff shall be performed; informing the mobile station on the new radio channels, new time slot identifier and digital voice colour codes to be used by the particular mobile station and target base station for the established connection after handoff; at least after receiving at the target base station information that a handoff shall be performed, transmitting from the target base station radio signals comprising the new time slot identifier code on the radio channel to be used by the target base station for the connection after handoff; after receiving at the particular mobile station information that handoff shall be performed, using the new time slot identifier code at the mobile station to find the correct time slot and transmitting from the particular mobile station radio signals comprising the new time slot identifier code and digital voice colour code on the new radio channel; and after receiving at the target base station information that a handoff shall be performed and information on new radio channel and time slot identifier code to be used by the particular mobile station, checking at the target base station the appearence of radio signals comprising both the time slot identifier code and the digital voice colour code on the radio channel.
Claim 3
Dependent Claim
58 words
A method according to claim 1 comprising the further steps of: measuring the bit error rates on the established connection on the digital communication channel bith at the responsible base station and at the particular mobile station; and taking the results of the bit error rare measurements into account when determining when a handoff ought to be done.
Claim 4
Dependent Claim
76 words
A method according to claim 1 comprising the further steps of: selecting digital voice colour code independently of time slot identifier code; transmitting the same digital voice colour code with radio signals from at least two mobile stations served by the same responsible base station; and transmitting different digital voice colour codes from at lerast two mobile stationsd usin the same radio channel and time slot identifier code but being served by different responsible base stations.
Claim 5
Dependent Claim
128 words
A method according to claim 1 comprising the further steps of: measuring at the base station responsible for the connection with the particular mobile station the signal strength on the digital communication channel used for the connection of the mobile station; taking the results of signal strength measurements at responsible base station into account when determining whether a handoff ought to be done ; measuring at the target base station the signal strength on the digital communication channel of the established connection of the particular mobile station; reporting from the target base station the results of the measurements of signal strength on the digital communication channel; and taking the results of signal strength measurements at target basae station into account when determining whether the handoff shall be performed.
Claim 6
Dependent Claim
34 words
A method according to claim 1 wherein at least on of the selected radio channels is a radio channel used for a control channel by an othe base station than the responsible base station.
Claim 7
Dependent Claim
145 words
A method according to claim 4 comprising the further steps of: at the particular mobile station coding the digital information to be transmitted in a binary error detecting code; adding to the coded binary information a binary coded digital voice colour code modulo two; transmitting the modulo two sum with the radio signals from the particular mobile station; at the target base station demodulating the received radio signals to obtain binary coded information; adding the binary coded digital voice colour code to the binary coded information obtained from the received signals modulo two; decoding the modulo two sum at the target base station according to the error detecting code to detect possible errors; and using at the target base the absence of error in the modulo two sum as an indication on the appearence of the digital voice colour code in the radio signals received.
Claim 8
Dependent Claim
204 words
A base station for communication with mobile stations in a cellular mobile radio system having radio channels for time division multiple access communication channels in time slots in frames of the radio channels comprising: means for storing at least as many different time slot identifier codes as the number of time slots in a multi slot frame on the radio channels; means for transmitting bursts of radio signals in time slots in frames on the radio channels; means for incorporating in each burst transmitted from the base station one of the stored time slot identification codes indicative of the time slot of the frame of the channel where the burst is transmitted but independent of the base identity and radio channel where the burst is transmitted; means for receiving bursts of radio signals in time slots of frames on the radio channels; means for synchronizing the receiving means to received bursts by using the time slot identifier codes of received burst; means for identification of any of the predetermined time slot identifier codes when appearing in a received burst; and means for measuring the signal strength of a burst on a radio channel in a time slot determined by a time slot identifier code.
Claim 9
Dependent Claim
204 words
A base station for communication with mobile stations in a cellular mobile radio system having radio channels for time division multiple access communication channels in time slots in frames of the radio channels comprising: means for storing at least as many different time slot identifier codes as the number of time slots in a multi slot frame on the radio channels; means for transmitting bursts of radio signals in time slots in frames on the radio channels; means for incorporating in each burst transmitted from the base station one of the stored time slot identification codes indicative of the time slot of the frame of the channel where the burst is transmitted but independent of the base identity and radio channel where the burst is transmitted; means for receiving bursts of radio signals in time slots of frames on the radio channels; means for synchronizing the receiving means to received bursts by using the time slot identifier codes of received burst; means for identification of any of the predetermined time slot identifier codes when appearing in a received burst; and means for measuring the signal strength of a burst on a radio channel in a time slot determined by a time slot identifier code.
Claim 10
Dependent Claim
81 words
A base station according to claim 7 further comprising: means for storing a plurality of digital voice colour codes independent of the time slot identifier codes; means for incorporating in each burst transmitted from the base station one of the stored digital voice colour codes independent of the time slot identifier codes in the bursts and channel where the burst is transmitted; and means for identification of any of the predetermined digital voice colour codes when appearing in a received burst.
Claim 11
Dependent Claim
204 words
A mobile station for communication with base stations in a cellular mobile radio system having radio channels for time division multiple access communication channels in time slots in frames of the radio channels comprising: means for storing at least as many different time slot identifier codes as the number of time slots in a multi slot frame on the radio channels; means for transmitting bursts of radio signals in time slots in frames on the radio channels; means for incorporating in each burst transmitted from the base station one of the stored time slot identification codes indicative of the time slot of the frame of the channel where the burst is transmitted but independent of the mobile identity and radio channel where the burst is transmitted; means for receiving bursts of radio signals in time slots of frames on the radio channels; means for synchronizing the receiving means to received bursts by using the time slot identifier codes of received burst; means for identification of any of the predetermined time slot identifier codes when appearing in a received burst; and means for measuring the signal strength of a burst on a radio channel in a time slot determined by a time slot identifier code.
Claim 12
Dependent Claim
204 words
A mobile station for communication with base stations in a cellular mobile radio system having radio channels for time division multiple access communication channels in time slots in frames of the radio channels comprising: means for storing at least as many different time slot identifier codes as the number of time slots in a multi slot frame on the radio channels; means for transmitting bursts of radio signals in time slots in frames on the radio channels; means for incorporating in each burst transmitted from the base station one of the stored time slot identification codes indicative of the time slot of the frame of the channel where the burst is transmitted but independent of the mobile identity and radio channel where the burst is transmitted; means for receiving bursts of radio signals in time slots of frames on the radio channels; means for synchronizing the receiving means to received bursts by using the time slot identifier codes of received burst; means for identification of any of the predetermined time slot identifier codes when appearing in a received burst; and means for measuring the signal strength of a burst on a radio channel in a time slot determined by a time slot identifier code.
Claim 13
Dependent Claim
81 words
A mobile station according to claim 9 further comprising: means for storing a plurality of digital voice colour codes independent of the time slot identifier codes; means for incorporating in each burst transmitted from the mobile station one of the stored digital voice colour codes independent of the time slot identifier codes in the bursts and channel where the burst is transmitted; and means for identification of any of the predetermined digital voice colour codes when appearing in a received burst.
References Cited (Backward Citations)
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