EP0530165A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Mobile station-controlled handoff
Assignee: Telefonaktiebolaget LM Ericsson AB
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Filing: 1992-08-18
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Granted: —
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Expires: 2012-08-18
Abstract
Abstract A cellular mobile radio system wherein a mobile station (M1-M9) chooses an appropriate base station (B1-B10) and an appropriate carrier/time slot combination (Fig. 3) of a multicarrier time division multiplexed radio system for the purpose of call setup and handoff. The mobile station, while in communication with one base station, scans for least interfered channels as well as base stations stronger than the base station the mobile station is presently in communication with. The mobile station uses the information to determine when to initiate a call setup or handoff to prevent the quality of the mobile station's communication link from decreasing.
Inventors
- 👤 Dag Akerberg
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 17:30
CPC Classifications
H; H04; H04W; H04W36/00; H04W36/24; H04W36/30; H04W36/302
Claims Analysis
Total Claims: 40
Claim 1
Independent Claim
189 words
In a cellular mobile radio system having a plurality of base stations, a plurality of mobile stations and a plurality of other cellular systems which use the same channels and a similar channel selection technique, a method for allowing each of said mobile stations to select one of a plurality of traffic channels comprising the steps of: determining the signal strength of a signal between said mobile station and a first base station which is in communication with said mobile station; measuring the signal strength of a signal between said mobile station and other base stations; storing the identity of a base station with the strongest signal strength and storing an ordered list of a number of least interfered channels; updating the identity of said strongest base station and said list of a number of least interfered channels; comparing the signal strength of said first base station with the signal strength of said strongest base station; and selecting one of said least interfered channels and initiating a handoff to said strongest base station when said strongest base station is stronger than the first base station by a predetermined amount.
Claim 2
Dependent Claim
189 words
In a cellular mobile radio system having a plurality of base stations, a plurality of mobile stations and a plurality of other cellular systems which use the same channels and a similar channel selection technique, a method for allowing each of said mobile stations to select one of a plurality of traffic channels comprising the steps of: determining the signal strength of a signal between said mobile station and a first base station which is in communication with said mobile station; measuring the signal strength of a signal between said mobile station and other base stations; storing the identity of a base station with the strongest signal strength and storing an ordered list of a number of least interfered channels; updating the identity of said strongest base station and said list of a number of least interfered channels; comparing the signal strength of said first base station with the signal strength of said strongest base station; and selecting one of said least interfered channels and initiating a handoff to said strongest base station when said strongest base station is stronger than the first base station by a predetermined amount.
Claim 3
Dependent Claim
36 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular radio system according to claim 1, wherein said predetermined amount is in the range of 6-10 decibels.
Claim 4
Dependent Claim
43 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular radio system according to claim 1, wherein said list of least interfered channels is ordered according to the amount of interference on each channel.
Claim 5
Dependent Claim
37 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular radio system according to claim 1, wherein said channel with lowest signal strength is first selected at handoff.
Claim 6
Dependent Claim
92 words
A met hod for allowing mobile station to select one of a plurality of traffic channels in a cellular radio system according to claim 1, further comprising the steps of: checking the signal strength of its own received communication signal every frame; determining whether the field strength has decreased by a predetermined amount for a predetermined number of consecutive frames; and updating the identity of said strongest base station and said list of least interfered channels when said field strength has decreased by said predetermined amount for said predetermined number of frames.
Claim 7
Dependent Claim
57 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular radio system according to claim 7, further comprising the step of changing antenna diversity at said first base station when it is determined that the signal strength of said first base station has decreased by said predetermined amount.
Claim 8
Dependent Claim
56 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular radio system according to claim 7, further comprising the step of changing antenna diversity at said mobile station when it is determined that the signal strength of said first base station is decreased by said predetermined amount.
Claim 9
Dependent Claim
57 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular radio system according to claim 7, further comprising the step of interrupting communication with said first base station during a time slot so that said mobile station can scan for a stronger base station during said time slot.
Claim 10
Dependent Claim
169 words
In a cellular mobile radio system having a plurality of base stations, a plurality of mobile stations and a plurality of other cellular systems which use the same channels and a similar channel selection technique, a method for allowing each of said mobile stations to select one of a plurality of traffic channels comprising the steps of: determining the signal strength of a signal between said mobile station and a first base station which is in communication with said mobile station; measuring the signal strength of signals between said mobile station and other base stations; storing the identity of a base station with the strongest signal strength and storing an ordered list of a number of least interfered channels; updating the identity of said strongest base station and said list of a number of least interfered channels; detecting a number of transmission errors in said signal between said mobile station and said first base station; and initiating handoff when said number of transmission errors has reached a threshold value.
Claim 11
Dependent Claim
169 words
In a cellular mobile radio system having a plurality of base stations, a plurality of mobile stations and a plurality of other cellular systems which use the same channels and a similar channel selection technique, a method for allowing each of said mobile stations to select one of a plurality of traffic channels comprising the steps of: determining the signal strength of a signal between said mobile station and a first base station which is in communication with said mobile station; measuring the signal strength of signals between said mobile station and other base stations; storing the identity of a base station with the strongest signal strength and storing an ordered list of a number of least interfered channels; updating the identity of said strongest base station and said list of a number of least interfered channels; detecting a number of transmission errors in said signal between said mobile station and said first base station; and initiating handoff when said number of transmission errors has reached a threshold value.
Claim 12
Dependent Claim
62 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular radio system according to claim 9, wherein said handoff is made to an active channel on said first base station when the field strength of said signal between said mobile station and said first base station has not decreased by a predetermined amount.
Claim 13
Dependent Claim
36 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular radio system according to claim 10, wherein said predetermined amount is in the range of 6-10 decibels.
Claim 14
Dependent Claim
57 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular mobile radio system according to claim 9, further comprising the step of scanning for a stronger base station when the field strength has decreased by a predetermined amount and performing handoff when a stronger base station is found.
Claim 15
Dependent Claim
48 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular mobile radio system according to claim 12, wherein a handoff is made to an active channel of a first base station when a stronger base station is not located.
Claim 16
Dependent Claim
75 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular mobile radio system according to claim 9, further comprising the step of incrementing a counter when said transmission errors are detected, wherein said counter is incremented by a first predetermined amount for each time slot containing transmission errors and is decremented by a second predetermined amount for each time slot which does not contain transmission errors.
Claim 17
Dependent Claim
42 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular mobile radio system according to claim 14, wherein said first predetermined number is 3 bits and said second predetermined number is one bit.
Claim 18
Dependent Claim
39 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular mobile radio system according to claim 14, further comprising the step of resetting said counter to zero after a handoff.
Claim 19
Dependent Claim
38 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular mobile radio system according to claim 9, wherein said detecting step occurs at the beginning of each time slot.
Claim 20
Dependent Claim
38 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular mobile radio system according to claim 9, wherein said detecting step occurs at the end of each time slot.
Claim 21
Dependent Claim
41 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular mobile radio system according to claim 9, wherein antenna diversity at said first base station is changed when transmission errors are detected.
Claim 22
Dependent Claim
40 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular mobile radio system according to claim 9, wherein antenna diversity at said mobile station is changed when transmission errors are detected.
Claim 23
Dependent Claim
174 words
In a cellular mobile radio system having a plurality of base stations, a plurality of mobile stations and a plurality of other systems which use the same channels and a similar channel selection technique, a method for allowing each of said mobile stations to select one of a plurality of traffic channels comprising the steps of: determining the signal strength of a signal between said mobile station in an idle locked state and a first base station to which said mobile station is locked onto; measuring the signal strength of a signal between said mobile station and active traffic channels of other base station at regular intervals; storing the identity of a base station with the strongest signal strength; monitoring the signal strength of said signal between said mobile station and said first base station to determine if the signal strength has decreased by a predetermined amount; and updating the identity of the base station with strongest signal strength when said signal strength of said first base station has decreased by said predetermined amount.
Claim 24
Dependent Claim
174 words
In a cellular mobile radio system having a plurality of base stations, a plurality of mobile stations and a plurality of other systems which use the same channels and a similar channel selection technique, a method for allowing each of said mobile stations to select one of a plurality of traffic channels comprising the steps of: determining the signal strength of a signal between said mobile station in an idle locked state and a first base station to which said mobile station is locked onto; measuring the signal strength of a signal between said mobile station and active traffic channels of other base station at regular intervals; storing the identity of a base station with the strongest signal strength; monitoring the signal strength of said signal between said mobile station and said first base station to determine if the signal strength has decreased by a predetermined amount; and updating the identity of the base station with strongest signal strength when said signal strength of said first base station has decreased by said predetermined amount.
Claim 25
Dependent Claim
84 words
A method for allowing each mobile station to select one of a plurality of traffic channels in a cellular mobile radio system according to claim 21, further comprising the step of immediately updating in the mobile station the identity of the base station of the same system with strongest signal strength when transmission errors are detected for a predetermined number of slots and further comprising the step of unlocking said mobile station and locking it to another active channel on the strongest base station.
Claim 26
Dependent Claim
69 words
A method for allowing each mobile station to select one of a plurality of active traffic channels in a cellular mobile radio system according to claim 21, further comprising the step of unlocking said mobile station from said idle locked state and selecting and locking onto another active channel on a new strongest base station of the same system when said signal strength has decreased by said predetermined amount.
Claim 27
Dependent Claim
20 words
An apparatus according to claim 21, wherein said storing means also stores an ordered list of least interfered traffic channels.
Claim 28
Dependent Claim
31 words
An apparatus according to claim 24, wherein said list of least interfered traffic channels is updated when said signal strength of said first base station has decreased by said predetermined amount.
Claim 29
Dependent Claim
27 words
An apparatus according to claim 24, wherein said list of least interfered traffic channels is updated when transmission errors are detected for a predetermined number of slots.
Claim 30
Independent Claim
182 words
An apparatus for selecting traffic channels in a cellular mobile radio system having a plurality of base station, a plurality of mobile stations and a plurality of other cellular system which use the same channels and a similar channel selection technique, wherein each mobile station contains: means for measuring the signal strength to the signal between said mobile station and a first base station which is in communication with said mobile station and a signal between said mobile station and other base stations; means for storing the identity of a base station with strongest signal strength and an ordered list of a number of least interfered channels; means for updating the identity of said strongest base station and said list of a number of least interfered channels; means for comparing the signal strength of said first base station with the signal strength of said strongest base station; and means for selecting one of said least interfered channels and initiating a handoff to said strongest base station when said strongest base station is stronger than the first base station by a predetermined amount.
Claim 31
Independent Claim
182 words
An apparatus for selecting traffic channels in a cellular mobile radio system having a plurality of base station, a plurality of mobile stations and a plurality of other cellular system which use the same channels and a similar channel selection technique, wherein each mobile station contains: means for measuring the signal strength to the signal between said mobile station and a first base station which is in communication with said mobile station and a signal between said mobile station and other base stations; means for storing the identity of a base station with strongest signal strength and an ordered list of a number of least interfered channels; means for updating the identity of said strongest base station and said list of a number of least interfered channels; means for comparing the signal strength of said first base station with the signal strength of said strongest base station; and means for selecting one of said least interfered channels and initiating a handoff to said strongest base station when said strongest base station is stronger than the first base station by a predetermined amount.
Claim 32
Dependent Claim
82 words
An apparatus according to claim 27, wherein each of said mobile stations contain: means for checking the signal strength of its own received communication signal every frame; means for determining whether the field strength has decreased by a predetermined amount for a predetermined number of consecutive frames; and said updating means updates the identity of said strongest base station and said list of least interfered channels when said field strength has decreased by said predetermined amount for said predetermined number of frames.
Claim 33
Independent Claim
167 words
An apparatus for selecting traffic channels in a cellular mobile radio system having a plurality of base stations, a plurality of mobile stations and a plurality of other cellular systems which use the same channels and a similar channel selection technique, wherein each mobile station contains: means for determining the signal strength of a signal between said mobile station and a first base station which is in communication with said mobile station and the signal strength of signals between said mobile station and other base stations; means for storing the identity of a base station with strongest signal strength and storing an ordered list of a number of least interfered channels; means for updating the identity of said strongest base station in said list of a number of least interfered channels; means for detecting a number of transmission errors in said signal between said mobile station and said first base station; and means for initiating handoff when said number of transmission errors has reached a threshold value.
Claim 34
Independent Claim
167 words
An apparatus for selecting traffic channels in a cellular mobile radio system having a plurality of base stations, a plurality of mobile stations and a plurality of other cellular systems which use the same channels and a similar channel selection technique, wherein each mobile station contains: means for determining the signal strength of a signal between said mobile station and a first base station which is in communication with said mobile station and the signal strength of signals between said mobile station and other base stations; means for storing the identity of a base station with strongest signal strength and storing an ordered list of a number of least interfered channels; means for updating the identity of said strongest base station in said list of a number of least interfered channels; means for detecting a number of transmission errors in said signal between said mobile station and said first base station; and means for initiating handoff when said number of transmission errors has reached a threshold value.
Claim 35
Dependent Claim
47 words
An apparatus according to claim 29, further including a counting means wherein said counting means is incremented by a first predetermined amount for each time slot containing transmission errors and is decremented by a second predetermined amount for each time slot which does not contain transmission errors.
Claim 36
Independent Claim
186 words
An apparatus for selecting traffic channels in a cellular mobile radio system having a plurality of base stations, a plurality of mobile stations and a plurality of other cellular systems which use the same channels and a similar channel selection technique, wherein each mobile station contains: means for determining the signal strength of a signal between said mobile station in an idle locked state and a first base station to which said mobile station is locked onto and the signal strength of a signal between said mobile station and active traffic channels of other base stations at regular intervals; means for storing the identity of a base station with strongest signal strength; means for monitoring the signal strength of said signal between said mobile station and said base station to determine if the signal strength is decreased by a predetermined amount; and means for updating the identity of the base station with the strongest signal strength when said signal strength has decreased by a predetermined amount; means for locking to another active channel on the strongest base station in the same system when bit errors occur.
Claim 37
Independent Claim
186 words
An apparatus for selecting traffic channels in a cellular mobile radio system having a plurality of base stations, a plurality of mobile stations and a plurality of other cellular systems which use the same channels and a similar channel selection technique, wherein each mobile station contains: means for determining the signal strength of a signal between said mobile station in an idle locked state and a first base station to which said mobile station is locked onto and the signal strength of a signal between said mobile station and active traffic channels of other base stations at regular intervals; means for storing the identity of a base station with strongest signal strength; means for monitoring the signal strength of said signal between said mobile station and said base station to determine if the signal strength is decreased by a predetermined amount; and means for updating the identity of the base station with the strongest signal strength when said signal strength has decreased by a predetermined amount; means for locking to another active channel on the strongest base station in the same system when bit errors occur.
Claim 38
Dependent Claim
35 words
An apparatus according to claim 31, wherein said locking means locks to another active channel on the strongest base station in the same system when another base station becomes stronger than the first base station.
Claim 39
Dependent Claim
20 words
An apparatus according to claim 31, wherein said storing means also stores an ordered list of least interfered traffic channels.
Claim 40
Dependent Claim
35 words
An apparatus according to claim 31, wherein said locking means locks to another active channel on the strongest base station in the same system when transmission errors are detected for a predetermined number of slots.
References Cited (Backward Citations)
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