US6549780B2
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for adjacent service area handoff in communication systems
Assignee: Qualcomm Inc
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Filing: 2000-12-29
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Granted: 2003-04-15
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Expires: 2020-12-29
Abstract
Abstract A handoff technique in which system users detect transitions in service between a current service area and an adjacent service area, and request a forward link channel in the new service area when a detected signal strength for the new service area exceeds predetermined threshold levels. The forward communications link in the current service area is maintained until the strength of the new service area signal reaches a certain level and appropriate channel quality is confirmed, as based on various known criteria. Typically, service area transitions are detected using the signal strength of pilot or paging signals associated with service areas, which are used to determine a relative signal strength of new service area signals. Pilot signal level adjustments used to counter roll-off effects are detected and compensated for in comparing signal levels. To minimize the burden on system resources, new service area signals are not selectable until a minimum time has passed, or a minimum change in energy from a prior pilot signal is detected. In addition, communications using the previous service area can be dropped almost immediately upon engaging the new service area.
Inventors
- 👤 Leonard N. Schiff
- 👤 David S. Miller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 23:26
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/14; H04B7/15; H04B7/185; H04B7/1853; H04B7/18539; H04B7/18541
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
211 words
A method for performing handoff between adjacent service areas in a wireless communication system that transfers communication signals using at least one central communications station which establishes geographical service areas for user terminals operating within the system, comprising the steps of: detecting a physical transition of a user terminal between a first service area and a second adjacent service area, each established by said one central communications station, by detecting signal strength for signals from said adjacent service areas; detecting the presence of signal strength adjusted to compensate for signal roll-off in said signals from said adjacent service areas and applying a compensation value to signal strength for each adjusted signal to obtain a non-adjusted value; requesting a forward link channel for use by said user terminal in said second service area, while said user terminal also communicates using said first service area for forward link communications, when a detected signal strength for the second adjacent service area at least equals that of said first service area; confirming that said forward link channel for said second service area is operating according to a preselected minimum quality level; and disengaging use by said user terminal of the forward link for said first service area upon confirmation of said preselected minimum quality level.
Claim 2
Independent Claim
211 words
A method for performing handoff between adjacent service areas in a wireless communication system that transfers communication signals using at least one central communications station which establishes geographical service areas for user terminals operating within the system, comprising the steps of: detecting a physical transition of a user terminal between a first service area and a second adjacent service area, each established by said one central communications station, by detecting signal strength for signals from said adjacent service areas; detecting the presence of signal strength adjusted to compensate for signal roll-off in said signals from said adjacent service areas and applying a compensation value to signal strength for each adjusted signal to obtain a non-adjusted value; requesting a forward link channel for use by said user terminal in said second service area, while said user terminal also communicates using said first service area for forward link communications, when a detected signal strength for the second adjacent service area at least equals that of said first service area; confirming that said forward link channel for said second service area is operating according to a preselected minimum quality level; and disengaging use by said user terminal of the forward link for said first service area upon confirmation of said preselected minimum quality level.
Claim 3
Dependent Claim
37 words
The method of claim 1 further comprising the steps of: using said central station as a gateway; and establishing said first and second adjacent service areas using first and second satellite beams, respectively, from a single satellite.
Claim 4
Dependent Claim
37 words
The method of claim 1 comprising the steps of: using said central station as a base station; and establishing said first and second adjacent service areas using first and second sectors, respectively, from said single base station.
Claim 5
Dependent Claim
51 words
The method of claim 1 wherein said step of detecting a transition between first and second service areas comprises the step of detecting a new pilot signal associated with said second service area; and the step of detecting signal strength comprises detecting a relative signal strength of said new pilot signal.
Claim 6
Dependent Claim
51 words
The method of claim 4 wherein each service area has a corresponding pilot signal, and said step of detecting a new pilot signal comprises the steps of: receiving pilot signals with at least one user terminal receiver; measuring signal strength of each received pilot signal; and comparing pilot signal strength measurements.
Claim 7
Dependent Claim
59 words
The method of claim 4 wherein each service area has a corresponding pilot signal, and said step of detecting a new pilot signal comprises the steps of: receiving pilot signals with at least one user terminal receiver; measuring signal strength of each received pilot signal; and reporting said signal strength of each received pilot signal to said central station.
Claim 8
Dependent Claim
29 words
The method of claim 6 further comprising the steps of: receiving said signal strength of each received pilot signal at said central station; and comparing pilot signal strength measurements.
Claim 9
Dependent Claim
25 words
The method of claim 7 further comprising the step of transmitting at least one signal to said user terminal indicating results of said comparison step.
Claim 10
Dependent Claim
25 words
The method of claim 6 further comprising reporting said signal strength of each received pilot signal to said central station on a predetermined periodic basis.
Claim 11
Dependent Claim
57 words
The method of claim 1 wherein the step of detecting a transition between first and at least a second service areas comprises the step of detecting a new paging signal associated with said second service area; and the step of detecting signal strength comprises the step of detecting a relative signal strength of said new paging signal.
Claim 12
Dependent Claim
30 words
The method of claim 1 wherein the step of confirming comprises the step of determining when the new channel has sufficient energy to maintain a desired level of communication service.
Claim 13
Dependent Claim
33 words
The method of claim 1 wherein the step of confirming comprises the step of determining when the new channel has a sufficiently low error rate to maintain a desired level of communication service.
Claim 14
Dependent Claim
90 words
The method of claim 1 further comprising the steps of: synchronizing the timing of communication signals and forward link channels for said user terminal at said central station through both said first and second service areas upon receiving a request for a forward link channel for use by said user terminal in said second service area; and disengaging use of the forward link of said first service area and commencing use of said forward link channel for said second service area by said user terminal at substantially the same time.
Claim 15
Dependent Claim
213 words
Apparatus for performing handoff between adjacent service areas in a wireless communication system in which system users transfer communication signals using at least one central communications station which establishes geographical service areas for user terminals operating within the system, comprising: means for detecting a physical transition of a user terminal between a first service area and a second adjacent service area, each established by said at least one central communications station, by detecting signal strength for signals from said adjacent service areas; means for detecting the presence of signal strength adjusted to compensate for signal roll-off in said signals from said adjacent service areas; means for applying a compensation value to signal strength for each adjusted signal to obtain a non-adjusted value; means for requesting a forward link channel for use by said user terminal in said second service area, while said user terminal also communicates using said first service area for forward link communications, said request being made when a detected signal strength for the second adjacent service area at least equals that of said first service area; and means for disengaging use by said user terminal of the forward link for said first service area when said forward link channel for said second service area exceeds a preselected minimum quality level.
Claim 16
Dependent Claim
213 words
Apparatus for performing handoff between adjacent service areas in a wireless communication system in which system users transfer communication signals using at least one central communications station which establishes geographical service areas for user terminals operating within the system, comprising: means for detecting a physical transition of a user terminal between a first service area and a second adjacent service area, each established by said at least one central communications station, by detecting signal strength for signals from said adjacent service areas; means for detecting the presence of signal strength adjusted to compensate for signal roll-off in said signals from said adjacent service areas; means for applying a compensation value to signal strength for each adjusted signal to obtain a non-adjusted value; means for requesting a forward link channel for use by said user terminal in said second service area, while said user terminal also communicates using said first service area for forward link communications, said request being made when a detected signal strength for the second adjacent service area at least equals that of said first service area; and means for disengaging use by said user terminal of the forward link for said first service area when said forward link channel for said second service area exceeds a preselected minimum quality level.
Claim 17
Dependent Claim
34 words
The handoff apparatus of claim 14 further comprising: a gateway operating as said central station; and a single satellite establishing said first and second adjacent service areas using first and second satellite beams, respectively.
Claim 18
Dependent Claim
38 words
The handoff apparatus of claim 14 further comprising: a base station operating as said central station; and first and second sectors of a cell establishing said first and second adjacent service areas, respectively, using said single base station.
Claim 19
Dependent Claim
27 words
The handoff apparatus of claim 14 wherein said means for detecting transitions between adjacent service areas detects a new pilot signal associated with said second service area.
Claim 20
Dependent Claim
46 words
The handoff apparatus of claim 17 wherein said user terminal comprises: at least one pilot signal receiver, for receiving pilot signals each corresponding to a service area; means for measuring signal strength of each received pilot signal; and comparison means for comparing pilot signal strength measurements.
Claim 21
Dependent Claim
55 words
The handoff apparatus of claim 17 wherein said user terminal, comprises: at least one pilot signal receiver, for receiving pilot signals each corresponding to a service area; means for measuring signal strength of each received pilot signal; and message transmission means for reporting said signal strength of each received pilot signal to said central station.
Claim 22
Dependent Claim
24 words
The handoff apparatus of claim 19 wherein said reporting of said signal strength of each received pilot signal occurs on a predetermined periodic basis.
Claim 23
Dependent Claim
34 words
The handoff apparatus of claim 19 further comprising: message reception means at said central station for receiving said signal strength of each received pilot signal; and comparison means for comparing pilot signal strength measurements.
Claim 24
Dependent Claim
28 words
The handoff apparatus of claim 21 further comprising user terminal message means for transmitting at least one signal to said user terminal indicating results of said comparison step.
Claim 25
Dependent Claim
27 words
The handoff apparatus of claim 14 wherein said means for detecting transitions between adjacent service areas detects a new paging signal associated with said second service area.
Claim 26
Dependent Claim
30 words
The handoff apparatus of claim 14 wherein said means for disengaging comprises means for determining when the new channel has sufficient energy to maintain a desired level of communication service.
Claim 27
Dependent Claim
95 words
The handoff apparatus of claim 14 further comprising: timing means for synchronizing the timing of communication signals and forward link channels for said user terminal at said central station through both said first and second service areas upon receiving a request for a forward link channel for use by said user terminal in said second service area; and control means for disengaging use of the forward link of said first service area and for commencing use of said forward link channel for said second service area by said user terminal at substantially the same time.
References Cited (Backward Citations)
US4737978A
Cited
US4866710A
Cited
US5410728A
Cited
US5101501A
Cited
US5073900A
Cited
US5392453A
Cited
US5235633A
Cited
US5559866A
Cited
US5711004A
Cited
WO1995012297A1
Cited
WO1995012296A1
Cited
US5722068A
Cited
WO1995020865A1
Cited
US5697055A
Cited
US5691974A
Cited
US5901144A
Cited
US6070058A
Cited
US5732351A
Cited
US5722073A
Cited
US6128470A
Cited
US6016313A
Cited
US5987326A
Cited
US5978365A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2006-04-14 | 2006-10-14 | 2007-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2010-04-14 | 2010-10-14 | 2011-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2014-04-14 | 2014-10-14 | 2015-04-15 | $7700.00 | Window Closed / Lapsed |