Multiplex communications – Communication over free space – Having a plurality of contiguous regions served by...
Reexamination Certificate
1997-03-19
2001-02-20
Olms, Douglas (Department: 2661)
Multiplex communications
Communication over free space
Having a plurality of contiguous regions served by...
C370S415000
Reexamination Certificate
active
06192039
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to methods for flow control, and more particularly to a flow control method directed to a hand-over process inherent in a telecommunication system in which an ATM system is applied to a multimedia mobile telecommunication network of a microcell system.
2. Description of the Related Art
Recently, there has been considerable activity in the research and development of a high-rate multimedia transmission in mobile telecommunications. Such a system is required to reduce the transmission power. It is thus required to reduce the telecommunication zone (cell) covered by a single base station and to employ a radio zone as narrow as approximately 100 m. It should be noted that the zone covered by one base station in a conventional automobile or portable telephone system is as large as approximately a few kilometers. When the radio zone is narrow as described above, a mobile station traveling at a high speed will go out of the current radio zone soon and enter another radio zone. Hence, it is required to use a hand-over process directed to prevent a communication from being interrupted. The hand-over process switches the base stations when the mobile station travels over radio zones so that the mobile station can continue to communicate with the other station.
In the conventional mobile telecommunication system, a communication is instantaneously broken for a time of 0.7-0.8 seconds when the channel used in the communication is switched. This is caused by an event in which data transferred over a transmission path is merely lost during the hand-over process. The instantaneous break of communication causes a loss of speech or data and results in a degradation in the communication quality. Particularly, the instantaneous break is a serious problem when data is transferred between data processing devices such as computers. Generally, if a loss of data occurs, a retransmission of data is required. However, such a data retransmission increases traffic. If a relatively narrow radio zone is employed, the hand-over should be frequently carried out. In this case, it is very important to consider problems due to the instantaneous break. In order to eliminate the problems caused by the instantaneous break, it is necessary to improve not only the radio channel switching technique but also the flow control of the whole telecommunication system and to thus prevent data from being lost during the hand-over process.
SUMMARY OF THE INVENTION
It is a general object of the present invention to provide a flow control method, a node, a telecommunication system employing the same, in which the above disadvantages are eliminated.
A more specific object of the present invention is to prevent data from being lost during a hand-over process and provide reliable mobile communication services.
The above objects of the present invention are achieved by a method for a flow control to a mobile communication network in which an ATM virtual channel established between a first base station having a radio zone in which a mobile station exists and a terminating ATM node to which a remote station with which the mobile station communicates is connected, the method comprising the steps of: (a) queuing, in an ATM node, incoming cells to be sent to a second base station having a radio zone when the mobile station is handed over to the radio zone of the second base station; and (b) stopping queuing and sending the incoming cells queued in the ATM node to the second base station after the mobile station is handed over.
The above method may be configured so that the ATM node in which the incoming cells are queued at the step (a) accommodates the first and second base stations.
The method may be configured so that the ATM node in which the incoming cells are queued at the step (a) is an ATM node connected to a first ATM node accommodating the first base station and a second ATM node accommodating the second base station.
The above objects of the present invention are also achieved by a method for a flow control to a mobile communication network in which an ATM virtual channel established between a first base station having a radio zone in which a mobile station exists and a terminating ATM node to which a remote station with which the mobile station communicates is connected, the method comprising the steps of: (a) sending hand-over start information to an ATM node accommodating the first base station therefrom when the mobile station moves to a radio zone covered by a second base station; (b) recognizing, in an ATM node in which the ATM virtual channel between the mobile station and the remote station is formed even after a hand-over, an ATM transmission path and an ATM virtual channel directed to the second base station; (c) queuing, in the ATM node, incoming cells to be transferred via the recognized ATM transmission path; (d) sending hand-over end information to the ATM node from the second base station when the hand-over is completed; (f) recognizing, from the hand-over end information, the ATM transmission path and the ATM virtual channel directed to the second ratio base station; (g) stopping queuing at the step (c) and outputting the incoming cells queued to the second base station via the recognized ATM transmission path.
The above method may be configured so that it further comprises the steps of transferring the hand-over start information and the hand-over end information over the ATM transmission path between the first and second base stations and the terminating ATM node so that ATM nodes located in the ATM transmission path receive the hand-over start information and the hand-over end information, whereby the ATM nodes queue cells directed to the second base station in a distributed formation.
The method may be configured so that the step (c) queues the incoming cells in a buffer provided to an input ATM transmission path connected to an upper ATM node.
The above objects of the present invention are also achieved by a method for a flow control to a mobile communication network having a hierarchical structure formed by base stations, ATM nodes directly connected thereto and other ATM nodes, wherein a mobile station located in a radio zone of a first base station communicates with a remote station via an ATM virtual channel formed therebetween, the method comprising the steps of: (a) sending hand-over start information from the first base station to an ATM node accommodating the first base station when the mobile station moves to a second radio zone accommodated in a second base station, the hand-over start information concerning the second base station and an ATM virtual channel established for the mobile station; (b) recognizing, from the hand-over start information, an ATM transmission path and an ATM virtual channel directed to the second base station; (c) queuing, in an upper ATM node located at a hierarchical level higher than the first and second base stations, incoming cells to be transferred via the recognized ATM transmission path; (d) sending hand-over end information to the upper ATM node from the second base station when the hand-over is completed, the hand-over end information including information concerning the second base station and an ATM virtual channel newly established for the mobile station which is handed over thereto; (f) recognizing, in the upper ATM node, the ATM transmission path and the ATM virtual channel directed to the second base station from the hand-over end information; (g) stopping queuing at the step (c) and outputting the incoming cells queued to the second base station via the recognized ATM transmission path.
The method may be configured so that it further comprises the step of transferring the hand-over start information and the hand-over end information over the ATM transmission path between the first and second base stations and the terminating ATM node so that ATM nodes located in the ATM transmission path receive the hand-over start information and the hand-over end information,
Nishio Masaya
Shinagawa Noriteru
Tanaka Motoharu
Watanabe Yoneo
Ladas & Parry
Olms Douglas
Vanderpuye Kenneth
YRP Mobile Telecommunications Key Technology Research Laboratori
LandOfFree
Method for flow control, node and communication network... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for flow control, node and communication network..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for flow control, node and communication network... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2607101