Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-10-20
2001-11-13
Kincaid, Lester G. (Department: 2682)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S446000, C455S067150
Reexamination Certificate
active
06317596
ABSTRACT:
TECHNICAL FIELD
The invention relates to error detecting and reporting system in a wireless communication network, and more particularly, to error detecting and reporting system utilizing a subscriber terminal to monitor call state information leading to a link failure.
BACKGROUND
Wireless communication typically involves the transmission of information between a subscriber terminal
200
, such as a cellular telephone or pager, and a cell station or base station. In such a communication system, the subscriber terminal
200
utilizes radio-frequencies (“rf”) to communicate with relatively low-powered and limited-radiation coverage cell stations arranged in a cellular pattern. As a result, the wireless communication systems of this type are prone to call failures caused by bad coverage areas in the rf communications link.
In an indoor wireless system, there are number of sources of interference which may be encountered. For instance, for systems transmitting in the industrial and scientific band, around 2.4 GHz, interference may arise from other sources within the same band, like microwave ovens and security systems. For systems transmitting in the narrowband personal communication services, between 900 and 950 MHz, interference may be caused by barcode readers and child monitoring systems. For cordless telephones in 47 MHz band, random radio signals from other phones lead to spontaneous ringing and squawking noises. These interferences will eventually lead to undesirable link failures. In addition, coverage can be interrupted by rf shields, such as metal walls.
Determining the exact cause of such failure is often difficult as rf propagation characteristics vary greatly within a building. Predicting optimum cell station placement to prevent such problems has proven difficult. Predicting post-installation building modifications and user traffic patterns is similarly problematic. It has been suggested that an installation provide user problem reporting system. However, in practice, it has been found that users either provide unreliable information regarding rf coverage or neglect to accurately record failure conditions.
SUMMARY
Accordingly, it is desirable to provide a technique for automatically detecting a link failure at the subscriber terminal and automatically having the subscriber terminal send a report to the system management entity for evaluation of rf coverage problems.
The present disclosure describes an error detecting and reporting system in a wireless communication network. The error detecting and reporting system utilizes a subscriber terminal which monitors some aspect of communication link conditions while active on a call. The subscriber terminal includes a call state information detection mechanism. The mechanism monitors and saves the call state information leading to a link failure in a non-volatile memory. A processing unit sends the saved call state information to a system management entity when the link is re-established. The system management entity utilizes the call state information as part of a system performance activity by correlating the saved call state information with related system events to determine system problems.
In a preferred embodiment, the saved call state information includes a time stamp, link error types, link error states, area information and rf signal strengths. It uses area information and rf signal strengths in a triangulation method to determine the location of the problem coverage area. In a further embodiment, the system management entity processes the saved call state information in certain statistical way to generate visual display of error reports. In a further preferred embodiment, the call state information detection mechanism correlates the saved call state information with information from a Global Positioning System receiver unit to locate the problem coverage area.
Other embodiments and advantages will become apparent from the following description and from the claims.
REFERENCES:
patent: 5095500 (1992-03-01), Tayloe et al.
patent: 5442679 (1995-08-01), Regis et al.
patent: 5694451 (1997-12-01), Arinell
patent: 5884163 (1999-03-01), Hardouin
patent: 6088588 (2000-07-01), Osborne
Denso Corporation
Fish & Richardson P.C.
Kincaid Lester G.
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