EP0637142A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Cellular communications by satellite with scheduled handoffs
Assignee: Motorola Solutions Inc
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Filing: 1994-06-27
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Granted: —
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Expires: 2014-06-27
Abstract
Abstract A cellular communications network (116) includes satellites (400) which project cells (200) toward the earth (104). The satellites (400) and cells (200) move relative to the earth (104). When a call is being set up (604) to a subscriber unit (300), data describing the subscriber unit's location are sent (702) to a switching office (500) of the network (116). The switching office (500) generates a schedule (800) which forecasts when movement of the cells (200) will cause the subscriber unit (300) to cross cell boundaries. During an ongoing call (606), the subscriber unit (300) determines (916) when scheduled boundary crossings occur. So long as an adequate signal is present (1108) in a scheduled cell (200) and network capacity exists (1204) in the scheduled cell (200) to handle the call, the call will be handed off (1206, 1208) to the scheduled cell (200). The subscriber unit (300) also monitors signal strengths to determine when a traffic channel's signal is getting weak (904) and when an alternate cell's signal is stronger (908).
Inventors
- 👤 Stephen H. Moritz
- 👤 Ralph C. Gregg
- 👤 Theresa C. Wang
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 06:45
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/14; H04B7/15; H04B7/185; H04B7/1853; H04B7/18539; H04B7/18541; H04W; H04W36/00; H04W36/08; H04W36/083; H04W64/00; H04W84/00; H04W84/02; H04W84/04; H04W84/06
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
111 words
In a cellular communication system (116) which projects a plurality of cells (200) that move with respect to the earth (104), a method of handing-off subscriber unit communications between cells (200) comprising the steps of: determining (1502) a location of a subscriber unit (300) in a first cell (200); scheduling (1506), in response to said determining step (1502), a second cell (200) in which said subscriber unit (300) may reside in the future and upcoming timing corresponding to when said subscriber unit (300) may reside in said second cell (200); and transferring (1208) communications with said subscriber unit (300) to said second cell (200) in accordance with said scheduling step (1506).
Claim 2
Dependent Claim
70 words
A method of handing-off subscriber unit communications between cells (200) as claimed in Claim 1 additionally comprising the steps of: determining (902) whether said call becomes lost; identifying (1002) a reconnection cell (200) within which said subscriber unit (300) may communicate after said determining step (902) indicates that said call has been lost; and resuming (1004, 1006, 1008, 1010) communications with said subscriber unit (300) through said reconnection cell (200).
Claim 3
Dependent Claim
72 words
A method of handing-off subscriber unit communications between cells (200) as claimed in Claim 1 wherein said method additionally comprises the steps of: monitoring (1108) a signal strength at which said communications in said second cell (200) take place; and identifying (1102, 1104, 1108, 1112) an alternate cell (200) within which said subscriber unit (300) may communicate when said monitoring step (1108) indicates that said signal strength is below a predetermined level.
Claim 4
Independent Claim
113 words
A method of operating a subscriber unit (300) in accordance with a cellular communication system (116) which projects a plurality of cells (200) which move over the earth (104), said method comprising the steps of: receiving (704), through a first one of said cells (200), a schedule (800) that associates timing data (802) with a channel identity (804), said channel identity (804) being associated with a second one of said cells (200); monitoring (916) real time to determine when a time described by said timing data (802) from said schedule (800) occurs; and transferring (1208) communications from said first cell (200) to said second cell (200) in response to said monitoring step (916).
Claim 5
Dependent Claim
76 words
A method of operating a subscriber unit (300) as claimed in Claim 4 additionally comprising the steps of: determining (1108), in response to said monitoring step (916), whether said channel whose identity is listed in said schedule (800) in association with said timing data (802) indicates that communication in said second cell (200) is possible; and performing said transferring step (1208) when said determining step (1108) indicates that communication in said second cell (200) is possible.
Claim 6
Dependent Claim
59 words
A method of operating a subscriber unit (300) as claimed in Claim 4 wherein said receiving step (704) comprises the steps of: receiving (704) said schedule (800) during a step of initiating (604) a call involving said subscriber unit (300); and providing (1506) said schedule timing data (802) responsive to the time that said initiating step (604) is performed.
Claim 7
Dependent Claim
63 words
A method of operating a subscriber unit (300) as claimed in Claim 4 wherein said step of receiving (704) comprises the step of: receiving (704) a schedule (800) that associates a plurality of timing data items (802) with a corresponding plurality of channel identities (804) and wherein said plurality of channel identities (804) are associated with a corresponding plurality of said cells (200).
Claim 8
Dependent Claim
158 words
A cellular communications system (116) with scheduled handoffs comprising: a plurality of satellites (400) orbiting so as to move with respect to the earth (104), said satellites (400) collectively projecting a plurality of cells (200) toward the earth (104); a subscriber unit (300) in data communication with one of said satellites (400) through a first one of said cells (200), said subscriber unit (300) including a locator (114, 304, 306) for providing data describing a location for said subscriber unit (300); a scheduler (306), responsive to said locator (114, 304, 306), for generating a schedule (800) which associates a channel used in a second cell (200) of said plurality of cells (200) with timing data (802) that describe when said subscriber unit (300) may reside in said second cell (200); and means (302, 306), coupled to said scheduler (306), for transferring communications for said subscriber unit (300) to said second cell (200) in accordance with said schedule (800).
Claim 9
Dependent Claim
143 words
A subscriber unit (300) which undergoes scheduled handoffs and which operates in accordance with a cellular communications system (116) that projects a plurality of moving cells (200), said subscriber unit (300) comprising: a schedule receiver (302, 306) for receiving, via communications conducted in a first cell (200) of said plurality of moving cells (200), a schedule (800) that associates timing data (802) with a channel identity (804), said channel identity (804) being associated with a second cell (200) of said plurality of moving cells (200); a timer (310), coupled to said schedule receiver (302, 306), for monitoring real time to determine when a time described by said timing data (802) from said schedule (800) occurs; and means (302, 306), coupled to said timer (310), for transferring communications from said first cell (200) to said second cell (200) in accordance with said schedule (800).
Claim 10
Dependent Claim
83 words
A subscriber unit (300) as claimed in Claim 9 additionally comprising: means (306), coupled to said schedule receiver (302, 306), for initiating a call involving said subscriber unit (300); means (306), coupled to said call initiating means (306), for monitoring a signal strength at which communications take place during said call; and means (306), coupled to said monitoring means (306), for identifying an alternate cell (200) within which said subscriber unit (300) may communicate when said signal strength is below a predetermined level.
References Cited (Backward Citations)
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