Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
1999-01-20
2002-06-11
Olms, Douglas (Department: 2661)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S231000, C370S232000, C370S235000, C370S253000, C370S401000, C370S465000
Reexamination Certificate
active
06404777
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a network system, a band management apparatus, a transmitting apparatus, a network transmitting method, a band management method, and a transmitting method, for network data transmission.
BACKGROUND OF THE INVENTION
In recent years, systems for transmitting various types of data through a network have been widely used. One method for managing a bandwidth of a band used in plural transmitting/receiving systems uses a band management apparatus.
FIG. 10
shows a network system which uses the band management apparatus according to a prior art. Turning now to
FIG. 10
, reference numeral
101
designates a network,
102
designates a transmitting apparatus A,
103
designates a receiving apparatus A,
1004
designates a conventional band management apparatus,
1005
designates a conventional band management section,
106
designates an inquiry packet output unit,
108
designates a conventional processor,
109
designates a table storage unit,
110
designates a transmitting apparatus B,
111
designates a receiving apparatus B,
112
designates a transmitting apparatus C, and
113
designates a receiving apparatus C.
FIG. 11
shows a table for managing the number of packets. Hereinafter, a description will be given with reference to
FIGS. 10 and 11
.
The table storage unit
109
holds the table shown in FIG.
11
. The processor
108
sequentially reads a transmission source identifier (ID) and a receiving destination ID of a packet to be transmitted on the network from the table storage unit
109
and posts them to the inquiry packet output unit
106
. The number of lines is a finite number, i.e., “N” (N: positive integer), as can be seen from the table. The IDs are sequentially read in ascending order of 1−N, and when IDs on the N-th line have been read, the same reading operation is repeated. The inquiry packet output unit
106
adds the posted IDs to an inquiry packet, and outputs the resulting inquiry packet. The transmitting apparatuses A
102
, B
110
, and C
112
, and receiving apparatuses A
103
, B
111
, and C
113
respectively monitor the inquiry packet all the time. When a receiving apparatuses recognizes a match between the receiving destination ID of the inquiry packet and its own ID, it prepares for receiving a data packet which will be output toward the network
101
after a specified time elapses. When a transmitting apparatuses recognizes a match between the transmission source ID of the inquiry packet and its own ID, it packetizes data to-be-transmitted and then outputs the packetized data toward the network
101
after a specified time elapses. The receiving apparatus receives the packet and thereby receives the data from the transmitting apparatus. Then, the inquiry packet output unit
106
outputs a next inquiry packet. Thereafter, the operation is repeated in the same manner.
Each transmitting/receiving system uses the packets according to information contained in the table storage unit
109
, and thereby the band management unit
1004
ensures the number of packets to-be-allocated for each transmitting/receiving system, i.e., a bandwidth to-be-allocated for each transmitting/receiving apparatus.
FIG. 12
shows an example of a table into which information about bandwidth allocation is entered. In
FIG. 12
, the number of lines on the table “N” is 6. Assume that a total bandwidth is 6 Mbps in the whole network system.
When transmission between the transmitting apparatus A and the receiving apparatus A requires 3 Mbps, as can be seen from the table in
FIG. 12
, three out of six are allocated for them. Likewise, when transmission between the transmitting apparatus B and the receiving apparatus B requires 2 Mbs, two out of six are allocated for them, and when transmission between the transmitting apparatus C and the receiving apparatus C requires 1 Mbps, one out of six is allocated for them. The allocation positions in the table are arbitrary. In this manner, the bandwidth to-be-allocated for each transmitting/receiving system is ensured.
A description will be given of a case where VBR (variable Bit Rate) data is transmitted from the transmitting apparatus A. In such data transmission, the bandwidth required for the VBR data dynamically changes, and therefore, packets which can be transmitted with the maximum required band are always allocated for the corresponding transmitting/receiving system, or the transmitting apparatus A
102
posts the required bandwidth to the band management apparatus
1004
, which dynamically changes the bandwidth to-be-allocated.
FIG. 13
is a flowchart showing a procedure for dynamically allocating the number of packets according to the prior art. In Step
1304
, the transmitting apparatus A
102
decides whether or not the bandwidth to-be-allocated should be changed. When decided that it should be changed, in Step
1305
, the transmitting apparatus A
102
posts a change request to the band management apparatus
1004
. In Step
1302
, the band management apparatus
1004
which has received the change request rewrites the contents of the table storage unit
109
to change the bandwidth to-be-allocated.
However, in the method in which the maximum required bandwidth is always allocated for the corresponding transmitting/receiving system, the maximum bandwidth should be ensured for a time period during which a small bandwidth might be necessary. For this reason, although there are free portions in the total bandwidth, another transmitting/receiving system cannot use them, which causes reduced efficiency in the use of the band. In addition, in the method in which the transmitting apparatus dynamically posts the change request, a procedure for posting the change request must be prepared for.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a network system, a band management apparatus, a transmitting apparatus, a network transmitting method, a band management method, and a transmitting method, wherein a bandwidth can be dynamically changed without the necessity of preparing for a procedure for posting a request for bandwidth change, and thereby efficiency in the use of the band is improved.
Other objects and advantages of the invention will become apparent from the detailed description that follows. The detailed description and specific embodiments described are provided only for illustration since various additions and modifications within the spirit of and scope of the invention will be apparent to those skilled in the art from the detailed description.
According to a first aspect of the present invention, a network system includes at least one transmitting apparatus connected to a network for outputting packets containing data to the network and at least one receiving apparatus connected to the network for receiving from the network the packets that have been output from the transmitting apparatuses. The transmitting apparatuses and the receiving apparatuses make up plural transmitting/receiving systems. The network system comprises: data packet monitoring means for monitoring the packets transmitted through the network and detecting the amount of data in the packets to be used by a specified transmitting/receiving system; and band management means for determining a bandwidth on the network to be used by the specified transmitting/receiving system, based on the amount of data in the packets that is detected by the data packet monitoring means.
According to a second aspect of the present invention, in the network system of the first aspect, the band management means holds a maximum value and a minimum value of a bandwidth to be allocated for the specified transmitting/receiving system, sets the bandwidth to be allocated for the specified transmitting/receiving system to the minimum value when the amount of data in the packet that is detected by the data packet monitoring means is zero, and sets the bandwidth to the maximum value when the amount of data in the packet is not zero.
According to a third aspect of the present invention, in the network syst
Hattori Toshikazu
Ibaraki Susumu
Hom Shick
Matsushita Electric - Industrial Co., Ltd.
Olms Douglas
Wenderoth , Lind & Ponack, L.L.P.
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