Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1999-01-29
2003-07-22
Kincaid, Lester G. (Department: 2685)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S436000
Reexamination Certificate
active
06597906
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to the field of telecommunications, and in particular, to wireless mobile telecommunications transmission/reception control based on relative geographical position information.
2. 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.
Even though the cause of the dead zones may not change position, the physical extent of these dead zones can change over the course of a day due to atmospheric condition changes, for example, and they may even have a different physical extent from one season to the next. To provide reliable and efficient communications with mobile units in communication areas where dead zones are present, attempts are sometimes made to minimize their effects. For example, additional antennae may be placed to cover the areas affected. However, because of cost and other considerations, it is virtually impossible to eliminate all dead zones.
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.
It can further be appreciated by those skilled in the art that mobile communications networks generally have to handle a large number of simultaneous mobile units attempting to communicate with a base station at any given time. To accommodate the units, multiplexing techniques are used where, for example, the limited base station bandwidth is divided into time slots and the units are time-division multiplexed. Generally, there is no prioritizing of transmission slot sharing and the resources are divided equally among units requesting transmission.
The present inventors realized that it would be advantageous to know exactly where the dead zones are relative to the mobile units in a communication system so that such problems could be anticipated and appropriate measures taken.
According to a copending application assigned to the same assignee as the present application, which became known to the present inventors subsequent to making their invention, 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, 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 that the user is approaching a dead zone (page 23, lines 12 to 17).
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.
In view of the above discussion, it is apparent that a need exists for additional ways to overcome the problems of potential data transmission losses and delays caused by unexpected or expected entries into dead zones.
A network processing system which ensures processing continuity by holding data received from a network accessible application for transmission to a mobile unit only when the mobile unit is in actual wireless communication with the network is known (see, e.g., U.S. Pat. No. 5,564,070).
A hierarchical communication system which provides adaptive data rate selection based on the detected quality of communication, and which provides for resolving conflicts among competing communications protocols on a priority basis, is known (see, e.g., U.S. Pat. No. 5,696,903).
A way of locating mobile end users of a communications system and routing messages to the end users as they roam between communication networks having local servicing offices is known. This is based on user specific information which is stored by the local servicing offices, an
Smith Gordon James
Van Leeuwen George Willard
Bussan Matthew J.
Kincaid Lester G.
Lynt Christopher H.
Mehrpour Naghmeh
Nock James R.
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