EP0593298A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Low-power wireless system for telephone services
Assignee: Nortel Networks Ltd
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Filing: 1993-10-14
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Granted: —
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Expires: 2013-10-14
Abstract
Abstract A small telephone system provides telecommunications services for personal wireless telephone sets over an area which is divided into service cells. Each of the cells is defined by reception characteristics of a plurality of radio base stations within the cell. During a call progress, if the wireless telephone set is mobile, a radio link with the set is handed off from one cell to another as the wireless telephone set moves along. The telephone system includes a service controller and a port being wireline connected between each radio base station and the service controller. The service controller selects radio base stations for setting up radio links with wireless sets of a calling or called persons, and responds to received signal strengths for handing a radio link from radio base station to radio base station, to maintain the quality of the radio link with an active mobile wireless telephone set.
Inventors
- 👤 Keith Daniel O'neill
- 👤 Alan Morris Redmond
- 👤 Jin Kue Wong
- 👤 Shoji Matsushita
- 👤 David Charles Ploeg
- 👤 Christian Jacques Szpilfogel
- 👤 Peter David Gale
- 👤 Garry Don Mah
- 👤 William Owen Bird
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 17:35
CPC Classifications
H; H04; H04W; H04W68/00; H04W36/00; H04W36/24; H04W36/30; H04W36/302; H04W48/00; H04W48/20; H04W36/08; Y; Y02; Y02D; Y02D30/00; Y02D30/70
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
221 words
A digital telephone system for providing communication paths for coupling station sets of calling and or called parties wherein the station sets may include portable sets and wherein a communication path associated with any portable set includes a radio link between the portable set and any one of a plurality of base station radios, each of which is connected by a communications conduit to the digital telephone system, the digital telephone system comprising: a port circuit for interfacing an operating signal format of a communications conduit with an operating signal format of the digital telephone system, the operating signal format of the communications conduit including a bidirectional message channel and at least one bidirectional communication channel, and the operating signal format of the digital telephone system including frame organized channels; a service controller for receiving and transmitting message signals via the frame organized channels, the service controller including a plurality of cell managers each being responsive to message signals received from any of the base station radios for causing one of the base station radios to maintain a radio link with the portable set of a calling or called party; and a switch being responsive to the service controller for transferring communication signals from a frame organized channel of any one port to a frame organized channel of any other port.
Claim 2
Dependent Claim
100 words
A telephone system comprising: a plurality of ports for transferring communications signals between radio base stations and channels in an operating signal format of the telephone system; a service controller being responsive to signalling received via a port associated with any of the radio base stations for selecting a one of the radio base stations from within the plurality of radio base stations for maintaining a radio link with a portable set of a calling or called party, and switch means being responsive to the service controller for providing a communication path via the port associated with said radio link.
Claim 3
Dependent Claim
33 words
A telephone system as defined in claim 2 wherein the service controller includes a plurality of cell managers each cell manager being logically associated with a predetermined plurality of the radio base stations.
Claim 4
Dependent Claim
46 words
A telephone system as defined in claim 3 wherein a reception characteristic of the predetermined plurality of radio base stations defines geographical operating limits of a cell within which a portable set may be radio linked with the telephone system under control of the cell manager
Claim 5
Dependent Claim
72 words
A telephone system as defined in claim 4 wherein each cell manager includes means responsive to signal strengths as received from time to time at any of its radio base stations including a radio base station being radio linked with a portable set, for transferring the radio link to another of its radio base stations contingent upon the other radio base station having received a greater signal strength from the portable set.
Claim 6
Dependent Claim
78 words
A telephone system as defined in claim 4 wherein each cell manager includes means responsive to signal strengths as received from time to time at any of its radio base stations including a radio base station being radio linked with a portable set for acting in concert with another cell manager to effect a handoff of the radio link from said radio base station to a one of the plurality of radio base stations in an neighbour cell.
Claim 7
Dependent Claim
340 words
In a small telephone system having a plurality of cells for wireless communication with portable sets each having a preassigned identity, wherein each cell includes a plurality of radio base stations, any one of which is operable to provide a radio link with a portable set over any one of a plurality of radio frequency channels, and wherein a portable set is operable to initiate the radio link by identifying at least one vacant radio frequency channel and then periodically broadcasting, in the identified radio frequency channel, a radio signal including a coded message corresponding to a preassigned identity of the portable set, a method for completing the radio link comprising the steps of: a) in one of the radio base stations detecting a receive signal strength indication (RSSI) level of the broadcast radio signal; b) registering the received RSSI level at said radio base station; c) in response to the RSSI level being greater than a portable originating link setup (POLS) threshold level, broadcasting, from said radio base station, an acknowledgement radio signal being indicative of the channel and the RSSI level of the radio link with said portable set, to a first cell manager associated with the radio base station; d) completing a telephone wireless connection between the radio base station and the portable set if, the RSSI level of the radio link therebetween is at least a value of an arbitration threshold; e) instructing cell managers associated with base stations in neighboring cells to send registered RSSI levels, associated with the channel used by the portable set, to the first cell manager, if the RSSI level is of a lesser value than the arbitration threshold and if the registered RSSI levels of neighboring cell managers is greater than the POLS threshold level; f) receiving, at the first cell managers, the registered RSSI levels of cell managers associated with neighboring cells to compare with the RSSI level of the radio link; and g) enabling completion of a radio link at a cell manager having the greatest RSSI level.
Claim 8
Dependent Claim
295 words
In a small telephone system having a plurality of cells for wireless communication with portable sets each having a preassigned identity, wherein each cell includes a plurality of radio base stations, any one of which is operable to provide a radio link with a portable set over any one of a plurality of radio frequency channels, a method of establishing a call between a radio base station and a portable set, wherein an originating radio link is established with the portable set of a called party, from a radio base station, comprising the steps of: a) receiving an incoming call request for a called party associated with a portable set; b) estimating the location of the portable set from amongst said plurality of cells; d) selecting radio base stations having vacant radio frequency channels in cells located near a probable location of the portable set; e) broadcasting a radio signal including a coded message corresponding to the preassigned identity of a called portable set in at least one vacant channel of each selected radio base station; f) after each radio signal broadcast, monitoring the at least one radio frequency channel for a portable set response broadcast including the identity of the called portable set; g) receiving the portable set response broadcast at a first radio base station if the portable set response broadcast is of a receive signal strength indication (RSSI) level greater than a switch originating link setup (SOLS) threshold level, and broadcasting a radio signal indicative of the channel and the RSSI level of the radio link with the called portable set to a first cell manager associated with said first radio base station; and h) establishing a radio link between the first base station and the portable set on said indicated channel.
Claim 9
Dependent Claim
41 words
A method as defined in claim 8, wherein a telephone wireless connection between the radio base station and the portable set is completed if, the RSSI level of the radio link therebetween is at least a value of an arbitration threshold.
Claim 10
Dependent Claim
97 words
A method as defined in claim 9, comprising the further steps of: in response to the RSSI level being of a lesser value than the arbitration threshold, instructing cell managers associated with base stations in neighboring cells to send registered RSSI levels, if greater than said SOLS threshold level, associated with said portable set to said first cell manager; receiving the registered RSSI levels of cell managers associated with neighboring cells and comparing with the RSSI level of the radio link; and enabling completion of a radio link at the cell manager having the highest RSSI level.
Claim 11
Dependent Claim
74 words
A method as defined in claim 8, wherein the location of said portable set is estimated, by: identifying and searching a first half of said plurality of cells; identifying and searching a second half of said plurality of cells if the portable set was not found in the first half; and searching all cells of said plurality of cells if the searches of the first and second half failed to locate the portable set.
Claim 12
Dependent Claim
42 words
A method as defined in claim 8, wherein the location of said portable set is estimated, by: randomly polling, at regular intervals, all portable sets; maintaining a positional histogram for each registered portable set, relative each cell in said plurality of cells.
Claim 13
Dependent Claim
93 words
A method as defined in claim 8, wherein the location of said portable set is estimated, by: forwarding a list of free frequency radio channels to each base station associated with separate groups of cells; and instructing a radio base station in a cell to select a frequency radio channel on said list for searching for the portable set, wherein each cell which uses a radio base station for searching is separated by at least one cell from any other cells which also uses a radio base station for searching the portable set.
Claim 14
Dependent Claim
236 words
In a small telephone system having a plurality of cells for wireless communication with portable sets each having a preassigned identity, wherein each cell includes a plurality of radio base stations, any one of which is operable to provide a radio link with a portable set over any one of a plurality of radio frequency channels, a method for maintaining an established radio link during mobile operation of the portable set while it may traverse a cell of established operation toward any neighbouring cell, the method comprising the steps of: a) periodically broadcasting radio signals in an established channel of operation, and receiving radio signals in the established channel of operation from the identified portable set via one of a plurality radio base stations in an established cell of operation; b) continuously registering receive signal strength indication (RSSI) levels in association with the one radio base station and generating a running average therefrom; c) in response to a drop in the running average being more than a predetermined amount, obtaining an RSSI level for the established channel via a radio base station in a neighbouring cell; d) in response to the RSSI level in the neighbouring cell being a predetermined amount more than an instant RSSI level in the cell of established operation, transferring the radio link to the radio base station in the neighbouring cell, whereby the neighbouring cell becomes the cell of established operation.
Claim 15
Independent Claim
231 words
A method of maintaining wireless telephony service for a portable telephone set during mobile operation of the portable set while it may traverse a cell of established operation toward any neighbouring cell, the method comprising the steps of: a) periodically broadcasting radio signals in an established channel of operation, and receiving radio signals in the established channel of operation from the identified portable set via a first radio base station in a cell of established operation; b) generating a running average of a receive signal strength indication (RSSI) level; c) in response to a drop in the running average being more than a predetermined amount, wherein the predetermined amount of drop in the running average is a first amount when the running average is of at least a first level, and the predetermined amount of drop in the running average is of a second amount, lesser than the first amount, when the running average is lesser than the first level, generating an RSSI level for the channel via a second radio base station in the neighbouring cell; d) in response to the RSSI level in the neighbouring cell being a predetermined amount more than an instant RSSI level in the cell of established operation, transferring the radio link to the second radio base station whereby the neighbouring cell becomes the cell of established operation and repeating steps a), b) and c).
Claim 16
Dependent Claim
55 words
A method as defined in claim 15, wherein the predetermined amount of drop in the running average in step c) is a first amount when the running average is of at least a first level and of a second amount lesser than the first amount when the running average is lesser than the first level.
Claim 17
Dependent Claim
72 words
A method as defined in claim 15 wherein the predetermined amount of drop in the running average in step c) ie either of a first amount, a second amount lesser than the first amount, and a third amount lesser than the second amount, in dependence upon the running average being either of greater than a first level, between the first level and a second level, and less than the second level, respectively.
Claim 18
Dependent Claim
71 words
A method as defined in claim 15 wherein the predetermined amount of drop in the running average in step c) is a first amount when a most recent apex in the level of the running average is of at least a first level and of a second amount lesser than the first amount when a most recent apex in the level of the running average is lesser than the first level.
Claim 19
Dependent Claim
80 words
A method as defined in claim 15 wherein the predetermined amount of drop in the running average in step c) ie either of a first amount, a second amount lesser than the first amount, and a third amount lesser than the second amount, in dependence upon a most recent apex in the level of the running average being either of greater than a first level, between the first level and a second level, and less than the second level, respectively.
Claim 20
Dependent Claim
37 words
A method as defined in claim 15 wherein the predetermined amount of drop in the running average in step c) is predetermined to be proportional to a most recent apex in the level of the running average.
References Cited (Backward Citations)
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