Multiplex communications – Data flow congestion prevention or control – Flow control of data transmission through a network
Reexamination Certificate
1997-07-25
2001-04-03
Olms, Douglas W. (Department: 2732)
Multiplex communications
Data flow congestion prevention or control
Flow control of data transmission through a network
C710S029000
Reexamination Certificate
active
06212166
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a data distribution method and a data distribution apparatus for distributing various different types of data items through a plurality of communication lines or networks such as satellite lines, ground wire lines, and the like.
2. Description of the Related Art
FIG. 25
is a diagram showing the configuration of a conventional data distribution apparatus that has been disclosed in Japanese laid-open publication number JP-A-7/143181. This conventional data distribution apparatus comprising a connection device
103
in a transmitter and a connection device in a receiver for selecting one of a digital communication satellite
101
and a digital ground line
102
according to predetermined conditions such as the amount of transmission data to be transmitted, connection types such as a broadcast communication and a one to one point communication, and a traffic of a line. The connection devices
103
and
104
in the transmitter and the receiver are used as network connection apparatus placed between a digital communication satellite as a digital transmission path to connect private networks and a digital ground network, and the private networks.
The connection device
103
(a central station GW) in the transmitter is connected to the private network
106
(a central station LAN) that is connected to a large-volume information storage source
105
such as a digital video server
105
and the like. On the other hand, each of the connection devices
104
in a receiver (branch GW) is connected to a video terminal
108
through each branch private network
107
. A video information broadcasting is performed from the connection device
103
in a transmitter to the connection device
104
in a receiver. In addition, a digital ground line or network connects the connection device in the transmitter
103
to the connection device
104
in a receiver. It is thereby possible to transmit control information and the like between them in two-way transmission.
FIG. 26
is a diagram showing a conventional process flow of a general transmission confirmation pattern. In the conventional transmission confirmation pattern, the transmission confirmation is performed on every receiving of a distribution data item. That is, the number of the distribution data items is equal to the number of the transmission confirmations. The timing to transfer the transmission confirmation is a time when the distribution data item is received.
FIG. 27
is a diagram showing a concept of a general configuration of a data communication system and a data process flow in which a receiver receives a data item and transmits a transmission confirmation to a transmitter (not shown). In the conventional data distribution system shown in
FIG. 27
, the control device
110
in a receiver receives a distribution data item through the satellite line
113
and then transfers this data item to the receive device
112
connected through the LAN
111
. The receive device
112
transmits the transmission confirmation to the transmitter (not shown).
There are following prior art techniques (1) to (11) (relating to the above data distribution technique).
(1) Japanese laid-open publication number JP-A-62/189823 shows a technique in which a ground line and a satellite line are switched according to the state of those lines, and the configuration and the length of transmission data. This technique uses a two-way satellite line. There is therefore a drawback in that it is nessary to place a satellite receiver having a highly installation cost at every required point.
(2) Japanese laid-open publication number JP-A-2/16847 shows a method to designate a requirement of a transmission confirmation when a receiver requests a data transmission to a transmitter. However, this technique is limited only to a PULL type data distribution in which the request transmitted from the receiver becomes a trigger. That is, this technique cannot be applied to a PUSH type data distribution caused by the transmitter. There is therefore a drawback that it is difficult to designate a transmission confirmation in the PUSH type data distribution.
(3) Japanese laid-open publication number JP-A-4/367135 shows a technique in which the load required for the processing of affirmation response is reduced by grouping a plurality of affirmation requests into one frame and transmitting it. However, there is a drawback that it takes many clock times to make the frame and to analyze the frame when the number of the affirmation requests is small and when a plurality of affirmation requests do not happened simultaneously. In addition to this drawback, there is a drawback in that processing must wait until a plurality of affirmation requests are generated in order to group them into one frame. Therefore this technique can not be applied to a data distribution to be executed at a high speed.
(4) Japanese laid-open publication number JP-A-4/207430 shows a method in which a transmitter divides a file into a plurality of sub-files and the transmission confirmation is performed only when the all sub-files have been transmitted to a receiver. This means that a transmission affirmation is performed after all of the original file (not every a divided sub-file) to be distributed in the transmitter is recieved. Therefore there is a drawback that the load of the transmitter becomes large when the number of distribution files or the number of receivers is increased, because the number of-transmission affirmations received by the transmitter becomes a value of (the number of transmitted files)×(the number of receivers).
(5) Japanese laid-open publication number JP-A-63/276928 shows a time division transmission point reservation method in which a shared transmission path is used as a transmission confirmation process during a desired time period. Because this conventional technique exclusively uses the transmission path during the desired time period, there is a drawback that it is difficult to use the transmission path for urgent transmission during this time period
(6) Japanese laid-open publication number JP-A-60/24749 shows a transmission confirmation method in which a transmission confirmation transferred from a relay node is canceled and, only a transmission confirmation and a re-transmission request transmitted from a receiver are accepted by a transmitter in a data communication system having relay nodes. This causes an increase load on the relay node because the relay node performs a transmission confirmation operation having no meaning.
(7) Japanese laid-open publication number JP-A-62/299142 shows a transmission confirmation method in which a control host in a receiver performs a transmission confirmation without waiting to receive a transmission confirmation transferred from the host in the receiver. Therefore there is a drawback that there is no consideration when the host in the receiver fails to receive the data. In addition to this drawback, there is no control meaning in transmitting the transmission confirmation data item from the host in the receiver to the receiver control host.
(8) Japanese laid-open publication number JP-A-62/189823 further shows a line combination communication method in which a target line to be used is selected according to a configuration of data, a size, a traffic state of a line and the like. However, it is not decided how to set and to use a threshold value of a data size when a current channel is switched in this method. Further, this method has a drawback that a distribution packet number per time is fixed and only a static time T=“td”דtx” is considered, where “td” is a time required for switching, and “tx” is a satellite delay time. Although the state of data communication using satellite lines is influenced by weather conditions, this method has a drawback in which there is no consideration for un-reached packet and transmission delay.
(9) Japanese laid-open publication number JP-A-62/285529 shows a satellite communication method of distributi
Akiyama Koji
Nakahara Shojiro
Tanaka Kouichi
D.D.Network Limited
Olms Douglas W.
Vanderpuye Ken
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