Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
2000-03-24
2004-04-13
Trost, William (Department: 2683)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S422100, C370S328000
Reexamination Certificate
active
06721572
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
The invention relates to the field of telecommunications, and in particular, to mobile communication, e.g., cellular voice and/or data, call optimization near wireless dead zone regions.
BACKGROUND INFORMATION
Mobile communication, e.g., cellular telephone communication, usually involves the exchange of radio transmission signals between a mobile unit (mobile client) and a base station. With ground-based mobile units, these radio transmission signals are often subject to a number of phenomena which can limit communication, including naturally occurring variations in geography, such as hills and valleys. This is because mobile communications is often based on a point-to-point, line-of-sight transmission path between the mobile unit and the base station. Terrain variations, man-made obstacles, and the like, can interfere with the communications, resulting in what are called “dead zones.”
Dead zones are geographical areas where communications signals do not penetrate or are too weak to provide for reliable communications. Such zones can be caused by radio signal shadowing, e.g., as occur when a mobile unit travels behind a hill, under a bridge or through a tunnel, or they can be due to signal reflections/images in radio signal patterns caused by the signals bouncing off radio-reflective objects, such as buildings, etc. An absorption of signals can also occur under certain circumstances resulting in a dead zone. For example, some non-reflective (¼ wavelength) coatings are known which are generally absorptive of particular radio signals, and such a phenomena can occur naturally as well.
With the advent of enhanced mobile personal communications equipment beyond the simple voice cell-phone to relatively more complex mobile data transmission and receiving devices, dead zones have become more than just a simple annoying interruption of a telephone conversation.
Some examples of the types of communications that are being considered, developed and/or implemented include traffic information updates, static and dynamic point-to-point routing, remote diagnostics, user comfort settings, and regional radio station detection and selection. A Concept Car was shown at the 1997 COMDEX show in Las Vegas, which incorporates so-called “telematics.” Telematics can include in car communication with the Internet for accessing e-mail, web pages, personal preference items (stocks, weather, sports, etc.), memos, navigation, car security/safety (911), as well as being expanded for video/movies for the passengers, for example. Along with these personal communications tools, if appropriate, an interface to the on-board vehicle control and diagnostic computer bus through an engine compartment firewall could be provided so that the user or remote fleet management system (for trucks) can run diagnostics on the automobile engine, as well as monitor vehicle progress on a route.
It should be apparent that, should a mobile unit enter a dead zone during a data transmission, substantial time and bandwidth may be wasted attempting a complete retransmission of the data when communication is impossible. More serious consequences could result due to a partially garbled and/or delayed transmission. For example, an investor might be attempting to conduct an on-line trade in the stock market where a delay of even a few minutes could mean the difference between a profitable trade and a missed opportunity.
According to a copending application assigned to the same assignee as the present application, Ser. No. 09/133,649, filed Aug. 13, 1998, entitled “ERROR CORRECTION FOR WIRELESS NETWORKS” (attorney docket YO998167): “methods, devices and systems are presented for providing service providers and/or end users of mobile stations to monitor and/or report regions with high error rates and/or dead zones . . . each mobile station periodically compares its current location with the data base [of locations with errors] . . . [T]he results of this comparison enables the mobile unit to anticipate connection problems” (Abstract, see also page 20, line 16 to page 21, line 18). The mobile unit uses an on-board GPS (global, positioning satellite system) to get its current location (see page 8, lines 4 to 20).
Further according to the copending application serial number 09/133,649, the mobile units include an error rate monitor to monitor a reception error rate, and a message processor to send an error message to a base station when the error rate rises above a preset threshold (page 21, line 19 to page 22, line 8). A database that contains records of all error messages may be maintained, used to map areas of reception dead zones, and queried by a mobile user to determine if the user is entering a dead zone—the base station may then inform the mobile user of an appropriate step to take to maintain connectivity (page 22, line 15 to page 23, line 2). According to the copending application, a user may be given a route to avoid dead zones, and/or given a warning signal, i.e., an audible alarm, that the user is approaching a dead zone (page 23, lines 12 to 17, page 38, lines 239 to 245, page 39, lines 259 to 261, and page 40, lines 262 to 263).
However, sometimes taking steps to maintain connectivity may not be convenient or even possible. For example, if the mobile unit is a large truck or even a passenger car, it may be that there is no place to pull over the mobile unit, turn around or otherwise take another route to avoid a dead zone. In some areas, such as the U.S. East Coast Interstate 95 North-South corridor, alternative routes are either limited or non-existent.
Further, while giving a warning signal as an audible alarm, that a dead zone is being, approached, as in copending application Ser. No. 09/133,649, may be useful, it would be advantageous to provide a mobile telecommunications user with more than just a warning signal.
However, the method disclosed in copending application Ser. No. 09/133,649, does not consider what should be done about a client exiting a dead zone. Further, a method for determining the location of a Dead Zone given in the copending application is to examine the error rates for transmissions. Error rates, however, may be due to a multitude of other factors besides a dead zone. For example, the transmitter may be faulty, the antenna on the transmitter may not be extended or is partially grounded, the batteries may be low in the mobile unit, there may be a temporary obstruction, etc.
A system providing improved wireless mobile telecommunications transmission/reception control based on relative geographical position information is known from copending application serial number 09/239,854; attorney docket RO998-230 (IBM-124), assigned to International Business Machines Corporation, filed Jan. 29, 1999, and entitled “MOBILE CLIENT-BASE STATION COMMUNICATION BASED ON RELATIVE GLOBAL POSITION INFORMATION.” As discussed in that application, a mobile communication device user's location, speed and direction can be determined using, for example, global positioning system satellites (GPS), and compared to a database of wireless topography to predict entry into so-called dead zones, and determine appropriate actions to take. As discussed in that application, data loss can be avoided when a communications system gives priority to a mobile unit transmitting or receiving data which is approaching a dead zone. Further, when the mobile unit knows of the approach of a dead zone, data transmission, either to or from the mobile unit in question, can be expedited or delayed. When the system can predict when a mobile unit will exit a dead zone, more efficient use of communications resources can be accomplished. Data to be transmitted to the mobile unit from the base station can be stored in anticipation of dead zone exit. Likewise, the mobile unit can buffer data transmission to the base station while in the dead zone in the same way. Scheduling and prioritization of communications, including expediting or delaying transmissions, based on location inf
Smith Gordon James
Van Leeuwen George Willard
Bussan Matthew J.
International Business Machines - Corporation
Le Danh
Lynt Christopher H.
Payne Leslie J.
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