EP0766489A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method for call establishment and rerouting in mobile computing networks
Assignee: AT&T Inc
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Filing: 1996-09-19
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Granted: —
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Expires: 2016-09-19
Abstract
Abstract A method for supporting end to end VC oriented service between mobile hosts includes protocols designed for a micro-cellular wireless environment in which mobile hosts make frequent transitions between cells. A VC rerouting procedure minimizes the effect of frequent hand-offs by extending routes and triggering a route rebuild only when performance as seen by an application degrades below a certain level. VC establishment and rerouting protocols assume the existence of separate signaling protocols for the wired and the wireless network, respectively. This minimizes the changes required to the signaling infrastructure used in the wired network while allowing the signaling in the wireless network to be customized for the unique requirements of that particular environment.
Inventors
- 👤 Partho Pratim Mishra
- 👤 Mani Bhushan Srivastava
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 14:46
CPC Classifications
H; H04; H04L; H04L49/00; H04L49/15; H04L49/1553; H04L45/00; H04L45/76; H04Q; H04Q11/00; H04Q11/04; H04Q11/0428; H04Q11/0478; H04L12/00; H04L12/54; H04L12/56; H04L12/5601; H04L2012/5603; H04L2012/5604; H04L2012/5607; H04L2012/5619; H04L2012/5625; H04L2012/5627; H04W; H04W40/00; H04W40/24; H04W40/34; H04W40/36
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
110 words
A method of call establishment in a communications network, wherein mobile user devices are wirelessly coupled to said network via base station units corresponding to a predetermined cell boundary in said network, said network including a virtual circuit (VC) messaging format, said method comprising the steps of: establishing a VC connection path between a mobile device and another endpoint in said network; and extending said VC path subsequent to said mobile device moving from a first cell boundary associated with a first base station to within a second cell boundary associated with a second base station, said first and second base station being coupled to a common local switching fabric.
Claim 2
Dependent Claim
101 words
The method of Claim 1, wherein said step of establishing said VC connection path includes the steps of: sending a connection setup request from said mobile device to an associated base station to thereby initiate a communication to said endpoint; and performing a handshake sequence between said mobile device and said associated base station, wherein said connection setup request is transmitted further in said network after completion of said handshake sequence, and wherein the VC establishment process is aborted if said mobile device moves out of the cell boundary of said associated base station prior to completion of said handshake sequence.
Claim 3
Dependent Claim
77 words
The method of Claim 2, wherein said step of establishing further includes the steps of: receiving a positive connection setup acknowledgment at said mobile device if said setup of said VC path is successful; and sending a connection setup confirmation from said mobile device to said endpoint, wherein dataflow towards said mobile device may begin after receipt thereof; and receiving a negative connection setup acknowledgment at said mobile device if said setup of said VC path fails.
Claim 4
Dependent Claim
40 words
The method of Claim 1, further including the steps of: monitoring performance characteristics of said VC path between said mobile device and said endpoint; and partially rebuilding said VC path based on reaching a predetermined threshold in said performance characteristics.
Claim 5
Dependent Claim
80 words
The method of Claim 4, wherein said VC path is partially rebuilt from a common ancestor switch in said path upon said mobile device registering with a base station outside of said local switch fabric, wherein said common ancestor switch is selected as a switch from which the path cost, measured in terms of delay, to the new base station is approximately the same cost as that to a first base station on a visit list of said mobile device.
Claim 6
Dependent Claim
19 words
The method of Claim 4, wherein said performance characteristics include measured delay, throughput, delay jitter and packet loss rate.
Claim 7
Independent Claim
117 words
A method of rerouting calls in a mobile computing network, wherein mobile hosts are wirelessly coupled to said network via base stations, said base stations being coupled to switching fabrics in said network, wherein said network includes a virtual circuit (VC) messaging format, said method comprising the steps of: establishing a VC connection path between a mobile device and another endpoint in said network; and extending said VC path subsequent to said mobile device moving from a previous base station to a current base station; monitoring performance characteristics of a specific application transmitted over said VC; and partially rebuilding said VC path when said performance characteristics as seen by said specific application degrade below a predetermined level.
Claim 8
Dependent Claim
59 words
The method of Claim 7, wherein said performance characteristics include measured delay, throughput, delay jitter and packet loss rate, wherein a predetermined value of one or more of said performance characteristics is used to trigger a rebuild in for both interactive and real-time applications and predetermined measures of throughput are used to trigger a rebuild for bulk data transfers.
Claim 9
Dependent Claim
101 words
The method of Claim 7, wherein said performance characteristics include measured delay, throughput. delay jitter and packet loss rate, and wherein said VC path is partially rebuilt from a common ancestor switch in said path upon said mobile device registering with a base station outside of said local switch fabric, wherein said common ancestor switch is selected as a switch from which the path cost, measured in terms of one or more of said performance characteristics, to the new base station is approximately the same cost as that to a first base station on a visit list of said mobile device.
Claim 10
Dependent Claim
68 words
The method of Claim 1 or 7, wherein multiple extensions in said VC path caused by movements of said mobile host between identical base stations in said network generate loops in said VC path of said mobile host, said method further including the step of: eliminating said loops in the VC path of said mobile host by determining the identity of repeated base stations occurring in said path.
Claim 11
Dependent Claim
151 words
The method of Claim 10, wherein said step of eliminating loops includes the steps of: sending a loop removal request from a current base station to the previously visited base station, wherein said loop removal request includes a list of VCI values for said mobile device and a list of base stations included in said loop; propagating said loop removal request along said loop back towards said current bases station, wherein each base station receiving said loop removal request substitutes a VCI value received for an input link by a VCI value of a corresponding output link, and substituting a VCI value received for an output link by a VCI value of a corresponding input link, thereby enabling said current base station to discover VCI values used by said mobile device during a previous visit to said current base station; and removing said loop running through said previously visited base station.
Claim 12
Dependent Claim
95 words
The method of Claim 1 or 7, wherein said step of extending said VC path includes the steps of: sending a registration request message from said mobile host to said current base station, said registration request message including an id of a previously visited base station and VCI values for all incoming and outgoing VCs of said mobile device; and performing a handshake between said mobile host and said current base station indicating successful exchange of said VCI values, wherein said current base station becomes the last base station visited after completion of said handshake.
Claim 13
Dependent Claim
111 words
The method of Claim 12, wherein said step of extending further includes the steps of: sending an extension request from said current base station to said previous base station, wherein said previous base station updates its routing tables; transmitting an extension acknowledge message from said current base station to said first base station to thereby acknowledge receipt of said extension request; and communicating an extension confirmation message from said current base station to said previous base station and an extension acceptance message to said mobile host, wherein receipt of said extension confirmation message and said extension acceptance message enables bi-directional data transfer between said mobile host and said current base station.
Claim 14
Dependent Claim
23 words
The method of Claim 11, wherein said steps of extending said VC path and eliminating said loops is performed in an aggregate fashion.
Claim 15
Dependent Claim
57 words
The method of Claim 11, wherein said current base station and said previously visited base station generate data flow markers during loop removal, wherein incoming data to said mobile device is buffered and removal of said loop is delayed until said data flow markers are received at said current base station, thereby ensuring against any data loss.
Claim 16
Dependent Claim
34 words
The method of Claim 14, wherein receipt of multiple extension requests and loop removal requests are serialized in processing by holding acknowledgment of a new request message until a previous message is completely processed.
Claim 17
Dependent Claim
23 words
The method of Claim 14, wherein receipt of multiple extension requests and loop removal requests are processed concurrently subject to barrier synchronization conditions.
Claim 18
Independent Claim
122 words
A system for rerouting calls in a mobile computing network, wherein mobile hosts are wirelessly coupled to said network via base stations, said base stations being coupled to switching fabrics in said network, wherein said network includes a virtual circuit (VC) messaging format, said system comprising:: means for establishing a VC connection path between a mobile device and another endpoint in said network; and means for extending said VC path subsequent to said mobile device moving from a previous base station to a current base station; means for monitoring performance characteristics of a specific application transmitted over said VC; and means for partially rebuilding said VC path when said performance characteristics as seen by said specific application degrade below a predetermined level.
Claim 19
Dependent Claim
110 words
The system of Claim 18, wherein said performance characteristics include measured delay, throughput, delay jitter and packet loss rate, and wherein said VC path is partially rebuilt from a common ancestor switch in said path upon said mobile device registering with a base station outside of said local switch fabric, further including means for selecting said common ancestor switch, wherein said common ancestor switch is selected as a switch from which the path cost. measured in terms of one or more of said performance characteristics, to the new base station is approximately the same cost as that to a first base station on a visit list of said mobile device.
Claim 20
Dependent Claim
65 words
The system of Claim 18, wherein multiple extensions in said VC path caused by movements of said mobile host between identical base stations in said network generate loops in said VC path of said mobile host, said system further including: means for eliminating said loops in the VC path of said mobile host by determining the identity of repeated base stations occurring in said path.
References Cited (Backward Citations)
No citation records indexed.
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