US5440561A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for establishing frame synchronization within a TDMA communication system
Assignee: Motorola Solutions Inc
•
Filing: 1991-09-30
•
Granted: 1995-08-08
•
Expires: 2011-09-30
Abstract
Abstract In a cellular TDMA communication system, prior to the handoff of a mobile unit (225) from a serving base-site (200) to a target base-site, (205 or 210) , the target base-site (205 or 210) establishes frame synchronization with the serving base-site (200). In this effort, first, the serving base-site timing is determined. Next, a timing difference between the serving base-site timing and a target base-site timing is calculated. Thereafter, frame positions within the serving base-site TDMA traffic channels are identified as a function of the timing difference in order to establish frame synchronization. Armed with this information, target base-sites (205 and 210) can continuously monitor all serving base-site (200) traffic channels for respective RSSI values. Preserving this information in memory enables fast and accurate signal strength determinations upon handoff.
Inventors
- 👤 Alton P. Werronen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 09:47
CPC Classifications
H; H04; H04J; H04J3/00; H04J3/02; H04J3/06; H04J3/0635; H04J3/0682; H04B; H04B7/00; H04B7/24; H04B7/26; H04B7/2662; H04B7/2671; H04B7/2678; H04B7/2684; H04W; H04W56/00
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
108 words
A method for establishing frame synchronization between a serving base-site and an adjacent base-site within a TDMA communication system comprising the steps of: said adjacent base-site determining serving base-site timing relative to adjacent base-site timing by: identifying at least one mobile unit serviced by the serving base-site, said mobile unit engaged in an active call; receiving at least some of the mobile unit's transmission signals; and processing the received signals to determine the serving base-site timing; calculating a timing difference between the serving base-site timing and the adjacent base-site timing; and said adjacent base-site identifying frame boundaries within a serving base-site TDMA traffic channel utilizing the timing difference.
Claim 2
Independent Claim
108 words
A method for establishing frame synchronization between a serving base-site and an adjacent base-site within a TDMA communication system comprising the steps of: said adjacent base-site determining serving base-site timing relative to adjacent base-site timing by: identifying at least one mobile unit serviced by the serving base-site, said mobile unit engaged in an active call; receiving at least some of the mobile unit's transmission signals; and processing the received signals to determine the serving base-site timing; calculating a timing difference between the serving base-site timing and the adjacent base-site timing; and said adjacent base-site identifying frame boundaries within a serving base-site TDMA traffic channel utilizing the timing difference.
Claim 3
Dependent Claim
97 words
The method according to claim 1 wherein the step of processing further comprises at least one of the following sets of steps: said adjacent base-site detecting a synchronization signal pattern within the mobile unit's RF communication signals, and said adjacent base-site identifying time slot positions within a serving base-site TDMA channel as a function of the synchronization signal pattern detection; and said adjacent base-site detecting a digital code within the mobile unit's RF communication signals, and said adjacent base-site identifying time slot positions within a serving base-site TDMA channel as a function of the digital code detection.
Claim 4
Dependent Claim
32 words
The method of claim 1 wherein the step of identifying frame boundaries comprises the step of approximating frame positions as a function of time slots identified within the serving base-site TDMA channel.
Claim 5
Dependent Claim
26 words
The method of claim 1 wherein the step of identifying frame boundaries further comprises the step of adding the timing difference to the adjacent base-site timing.
Claim 6
Independent Claim
166 words
A method for establishing frame synchronization between a serving base-site and a plurality of adjacent base-sites in a TDMA communication system, prior to the handoff of a candidate mobile unit, said method comprising the steps of: receiving, at the plurality of adjacent base-sites, radio frequency (RF) transmissions from at least one mobile unit serviced by the serving base-site, said mobile unit engaged in an active call; determining, at each of said adjacent base-sites, serving base-site timing, as a function of time slots identified within the received RF transmissions; calculating, for said each of said adjacent base-sites, a timing difference, said timing difference being the difference between the serving base-site timing established at an adjacent base-site and that adjacent base-site's timing; updating said each of said adjacent base-site's timing difference; identifying frame boundaries within a serving base-site TDMA traffic channel as a function of an updated timing difference; and scheduling serving base-site signal strength measurements from said each of said adjacent base-site utilizing the updated timing difference.
Claim 7
Independent Claim
166 words
A method for establishing frame synchronization between a serving base-site and a plurality of adjacent base-sites in a TDMA communication system, prior to the handoff of a candidate mobile unit, said method comprising the steps of: receiving, at the plurality of adjacent base-sites, radio frequency (RF) transmissions from at least one mobile unit serviced by the serving base-site, said mobile unit engaged in an active call; determining, at each of said adjacent base-sites, serving base-site timing, as a function of time slots identified within the received RF transmissions; calculating, for said each of said adjacent base-sites, a timing difference, said timing difference being the difference between the serving base-site timing established at an adjacent base-site and that adjacent base-site's timing; updating said each of said adjacent base-site's timing difference; identifying frame boundaries within a serving base-site TDMA traffic channel as a function of an updated timing difference; and scheduling serving base-site signal strength measurements from said each of said adjacent base-site utilizing the updated timing difference.
Claim 8
Dependent Claim
32 words
The method of claim 5 wherein said serving base-site timing and time slot identifications are determined as a function of at least one of: synchronization signal pattern detection; and digital code detection.
Claim 9
Dependent Claim
39 words
The method of claim 5 further comprising the steps of: measuring all serving base-site TDMA traffic channels for signal strength levels; updating each traffic channel's signal strength level; and storing each traffic channel's updated signal strength level in memory.
Claim 10
Dependent Claim
25 words
The method according to claim 7 further comprising the step of scanning and measuring all serving base-site TDMA traffic channels from adjacent base-site scan receivers.
Claim 11
Dependent Claim
61 words
The method according to claim 7 wherein the step of updating said each traffic channels signal strength level comprises the steps of: obtaining a number of signal strength samples over a predetermined period; summing the number of signal strength samples together; and dividing the signal strength sum by the number of samples in order to obtain an updated signal strength level.
Claim 12
Dependent Claim
56 words
The method of claim 5 further comprising the steps of: scanning and measuring all TDMA traffic channels within the TDMA communication system for signal strength levels; storing the signal strength levels in memory; updating the stored signal strength levels; and retrieving an updated signal strength level from memory, when a candidate mobile unit requires a handoff.
Claim 13
Dependent Claim
55 words
The method according to claim 10 wherein the step of updating stored signal strength level comprises the steps of: obtaining at least 4 signal strength samples over a two second period; summing the 4 signal strength samples together; and dividing the signal strength sum by 4 in order to obtain an updated signal strength level.
Claim 14
Dependent Claim
32 words
The method of claim 5 wherein the step of identifying frame boundaries further comprises the step of adding the updated timing difference obtained for an adjacent base-site to that base-site's respective timing.
Claim 15
Independent Claim
211 words
A method for establishing frame synchronization between a serving base-site and a plurality of adjacent base-sites in a TDMA communication system, prior to the handoff of a candidate mobile unit, said method comprising the steps of: receiving, at the plurality of adjacent base-sites, radio frequency (RF) transmissions from at least one mobile unit serviced by the serving base-site and engaged in an active call; determining, at each adjacent base-site, serving base-site timing, as a function of time slots identified within the received mobile's RF transmissions; calculating, for said each of said adjacent base-sites, a timing difference, said timing difference being the difference between the serving base-site timing established at an adjacent base-site and that adjacent base-site's timing; updating said each of said adjacent base-site's timing difference; identifying frame boundaries within a serving base-site TDMA traffic channel as a function of an updated timing difference; scheduling serving base-site signal strength measurements from said each of said adjacent base-site as a function of the updated timing difference; measuring all serving base-site TDMA traffic channels for signal strength levels; updating each traffic channel's signal strength level; storing said each traffic channel's updated signal strength level in memory; and retrieving an updated signal strength level from memory, when a candidate mobile unit requires a handoff.
Claim 16
Independent Claim
211 words
A method for establishing frame synchronization between a serving base-site and a plurality of adjacent base-sites in a TDMA communication system, prior to the handoff of a candidate mobile unit, said method comprising the steps of: receiving, at the plurality of adjacent base-sites, radio frequency (RF) transmissions from at least one mobile unit serviced by the serving base-site and engaged in an active call; determining, at each adjacent base-site, serving base-site timing, as a function of time slots identified within the received mobile's RF transmissions; calculating, for said each of said adjacent base-sites, a timing difference, said timing difference being the difference between the serving base-site timing established at an adjacent base-site and that adjacent base-site's timing; updating said each of said adjacent base-site's timing difference; identifying frame boundaries within a serving base-site TDMA traffic channel as a function of an updated timing difference; scheduling serving base-site signal strength measurements from said each of said adjacent base-site as a function of the updated timing difference; measuring all serving base-site TDMA traffic channels for signal strength levels; updating each traffic channel's signal strength level; storing said each traffic channel's updated signal strength level in memory; and retrieving an updated signal strength level from memory, when a candidate mobile unit requires a handoff.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-08-07 | 1999-02-06 | 1999-08-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-08-07 | 2003-02-06 | 2003-08-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-08-07 | 2007-02-06 | 2007-08-08 | $7700.00 | Window Closed / Lapsed |