Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-02-26
2001-03-27
Bost, Dwayne D. (Department: 2744)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
C455S426100, C455S428000, C455S012100, C340S988000
Reexamination Certificate
active
06208859
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a computer architecture and method of service preemption for mobile terminals in a mobile satellite communication system, and more particularly, to a computer architecture and method of performing continuous reception (full-duplex receiver function) during message channel transmission.
2. Background of the Related Art
FIG. 1
illustrates the general layout of a mobile communication system. A vehicle
18
, usually transporting cargo, moves along a transport route. The route can be one that is well known, or it can be one that is being newly travelled by the vehicle. The vehicle is preferably equipped with at least one mobile sensing station, which functions to detect predetermined events or conditions (such as collisions or impacts, potholes or uneven tracks or the like) along the travel route, and transmit data regarding those conditions using the mobile communicator system (not shown) via orbiting satellite
14
to a remote satellite ground station
8
via satellite antenna
10
. The satellite ground station
8
transfers the data received from the mobile communicator system to a dispatch or fleet management center to analyze and evaluate the data.
Part of the data transmitted from the mobile sensing station is positional data received or detected from satellite
14
or a separate satellite which is part of a satellite navigation system. Examples of presently available systems are LORAN or the current Global Position System (GPS).
Navigational data sent to the mobile sensing station preferably utilizes a Standard-C data protocol format, which is commonly used in the maritime industry. Experience has indicated that this is the most reliable method of sending navigational data from one mobile station to another. However, other navigation or location systems can be used. For example, a series of radio repeaters located along a predetermined route can track the location of a specific vehicle and can be used to send location data to the mobile communicator as is done by satellite
14
in FIG.
1
. Also, other data transfer formats can be used, depending on the navigational system, the transport route, the vehicle and the communication system for transmitting data from the mobile communicator system.
While
FIG. 1
illustrates communication between the mobile communicator system in vehicle
18
to satellite
14
, the mobile communicator system may also communicate with the fleet management center by means of a cellular telephone system. In this variation, a cellular transceiver is used capable of automatically accessing cellular ground station
4
as it passes from one cell into another. While such equipment may be more complex and expensive than the satellite uplink embodied in
FIG. 1
, it facilitates easy communication of instructions from the central controller to the mobile sensing station.
The fleet dispatch center includes a central controller that stores the data sent from the mobile communicator system and arranges it so that it can be used in a display, for example, by vehicle
18
. The central controller is expected to handle data from a variety of routes, each travelled by a plurality of vehicles optionally having mobile sensing stations. Since the data are preferably transmitted from the mobile communicator system in ASCII format, the user terminal can access selected data from the central controller using a personal computer (PC), a modem and standard communication software.
With the appropriate software, a display of the desired transport route can be generated at the PC terminal, and information is received from various vehicles having mobile communicator systems travelling along that route. For example, boat
16
in
FIG. 1
also includes a mobile communicator system for communication with satellite
14
. In addition, even vehicles or subscribers who do not contain the mobile communicator system can communicate with the mobile communicator system. For example, vehicle
20
may communicate with satellite
14
via cellular antenna
6
, cellular switching office
4
, satellite ground station
8
and satellite antenna
10
. Similarly, plain old telephone service (POTS) telephone
12
may also communicate with satellite
14
via switching office
8
, satellite ground station
8
and satellite antenna
10
. Thus, the mobile communicator system may be used to exchange data from among various different vehicles.
The Federal Communications Commission (FCC) has generally required communication system providers to provide some capability for securely and reliably transmitting a priority message in the presence of a priority event. Since various different users utilize the communication system, and the communication system provides the capability of supporting a wide audience, it is desirable to provide a priority and/or preemption capability that can transmit a priority and/or preemption message to various mobile communication systems.
I have determined that the priority and/or preemption capability preferably includes the ability to warn mobile communication systems of a preemption event that may be imminent. I have also determined that the priority and preemption capability must be implemented in an efficient and expedient manner to ensure that communication resources are freed in a timely manner to transmit a priority message. I have also determined that the priority and/or preemption capability optionally includes alteration of functionality in the mobile communication system to facilitate same.
SUMMARY OF THE INVENTION
It is a feature and advantage of the present invention to provide a priority and/or preemption capability that can transmit a priority and/or preemption message to various mobile communication systems.
It is another feature and advantage of the present invention to provide a priority and/or preemption capability preferably that includes the ability to warn mobile communication systems of a preemption event that may be imminent.
It is another feature and advantage of the present invention to provide a priority and preemption capability that is implemented in an efficient and expedient manner to ensure that communication resources are freed in a timely manner to transmit a priority message.
It is another feature and advantage of the present invention to provide a priority and/or preemption capability optionally includes alteration of functionality in the mobile communication system to facilitate same.
The present invention reduces the time for TDM scanning. By implementing the process described herein, the present invention keeps closer track of communication with the satellite. That is, the satellite and the MT operate on a time-based frequency, and they are not necessarily in synch. The satellite and MT get synched up every, for example, 8.64 seconds or bulletin board interval. Therefore, if one or more bulletin boards are missed, there is a chance that the MT may drift off and not be listening on a frequency that is not quite online with where the satellite is broadcasting. Therefore, the MT may have to be resynchronized, which will take more time.
The present invention provides two ways to address compliance with full duplex operation. A first method involves fast acquisition, where when the MT is in pre-emption mode, only short data packets are sent. The data packets are set up so that only one packet at a time is transmitted. The individual packets are then transmitted within the two second window or other time interval where interleaving may be used to reconstruct or substantially reconstruct the data. Thus, if only two seconds of data is transmitted, and the satellite is reacquired in the substantially same frame, then the entire bulletin board can be decoded/reconstructed so that the MT will be able to determine whether it is possible to transmit again or not.
In accordance with the present invention, a priority message is transmitted to all MTs to shut down to ensure that the priority message will be able to be transmitted immediately. The MT therefore
Bost Dwayne D.
Donner Irah H.
Hale and Dorr LLP
Motient Services Inc.
Redmon Joy K.
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