Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-07-21
2001-06-26
Trost, William G. (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S436000, C455S439000, C370S329000, C370S331000
Reexamination Certificate
active
06253083
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to wireless communication systems and, in particular, to a system for providing an improved method of processing handoffs between cells in wireless communication systems.
PROBLEM
It is a problem in the field of wireless communication systems to appropriately allocate cell site and network resources to serve the increasing demand for wireless communication services. There is presently a growing problem with the number of access failures for CDMA wireless communication service and the wireless communication system response to such failures. On a call origination/termination, the wireless communication system sends out a probe to identify the base stations that are available to serve the call origination/termination and their respective signal strengths with respect to the mobile subscriber station. There are typically multiple responses to this transmitted probe, since multiple base stations are in range of the mobile subscriber station.
Typically, the approach to addressing this problem of access failures for CDMA wireless communication service in IS-95B has been to adjust the operation of the mobile subscriber station and/or the base station. More specifically, To enhance the CDMA access, the IS-95B proposed the following procedures.
Access Entry Handoff
Access Probe Handoff
Access Handoff
Channel Assignment into Soft Handoff.
However, only the channel assignment into a soft handoff can result in a significant reduction in access failure. While each individual feature implemented in IS-95B can result in some performance improvement in access failures for CDMA wireless communication service, the piecemeal addressing of the problem of access failures for CDMA wireless communication service can result in wireless communication system overload due to additional call processing required for each of the new features. These features can also interact, blocking each other, resulting in the overload of the base station and the mobile switching center, which can cause fatal call processing errors. Thus, there presently no effective solution to the problem of access failures for CDMA wireless communication service.
SOLUTION
The above described problems are solved and a technical advance achieved in the field by the present system for wireless communication connection handoff service. This addresses the CDMA radio congestion problem from the mobile switching center point of view, thereby providing an approach to the problem of access failures for CDMA wireless communication service. In operation, the mobile subscriber station forms a message and forwards it to the mobile switching center to indicate the signal strength of the various base stations that have responded to the access probe through the different base stations. The mobile switching center saves this data for later use when the mobile subscriber station cannot access the would be selected base station due to any failures in the base station such as lack of speech coders, moving out of range, etc. when the mobile subscriber station moves out of range of the initially selected base station. The mobile switching center reviews the stored data and, if a CIC is available to one of the identified base stations, the channel is allocated and the stored data is flushed.
REFERENCES:
patent: 5301356 (1994-04-01), Bodin et al.
patent: 5901145 (1999-05-01), Sawyer
patent: 5953331 (1999-09-01), Duncan et al.
patent: 6112088 (2000-08-01), Haartsen
patent: 6119005 (2000-09-01), Smolik
patent: 6157834 (2000-12-01), Helm et al.
Bergren Mark
Hacena Farid
Duft, Graziano & Forest, P.C.
Lucent Technologies - Inc.
Tran Congvan
Trost William G.
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