Multiplex communications – Network configuration determination – Using a particular learning algorithm or technique
Reexamination Certificate
1998-09-11
2002-05-28
Chin, Wellington (Department: 2664)
Multiplex communications
Network configuration determination
Using a particular learning algorithm or technique
C370S230000, C370S235000, C370S238000
Reexamination Certificate
active
06396814
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of constructing a communication network and a communication system constructed by such a method.
First, a first conventional method art will be described. A technique for constructing a network ad hoc using a plurality of devices is disclosed in Jpn. Pat. Appln. No. 07-87937. In the network constructed based on Jpn. Pat. Appln. No. 07-87937, each device broadcasts a device message and exchanges the device message with each other. The device message contains the information on the device that has transmitted the message and the information on the devices recognizing that the communication is possible. By exchanging the device messages, therefore, the information can be collected on the status of the communication link between the surrounding devices. Thus a network can be constructed without a special setting. For actual data exchange and communication, a group is configured of a plurality of communicating devices, to which data are multicast to carry out efficient data transmission between a plurality of devices.
With the increase in the number of surrounding devices, however, an increased data amount is required for the device message exchanged through the network, thereby posing the problem of imposing a heavier burden on the band of the network.
Also, for a group to be formed as required for data exchange, a procedure is necessary to assure that the status of the devices constituting each group is coincident with each other and that required parameters such as a multicast address is set.
FIG. 7
shows an example of the procedure. First, a device attempting to form a group transmits a message
910
requesting other devices to form a group. The devices that have received the request message
910
send back a response message
911
to the first device. The first device, upon receipt of the response message
911
from all the other devices, transmits again an acknowledge message
912
to all the other devices. The procedure shown in
FIG. 7
is for forming a new group. A message is also exchanged in similar fashion between a requesting device and the other devices when a device joins a group or a group is disbanded.
In the example shown in
FIG. 7
, the device that has transmitted the requesting message
910
is required to process the response message
911
transmitted thereto from all the other devices. This poses the problem that a single device assumes a heavy load. This imbalance increases with the number of devices constituting a group.
Also, in many computer systems, when a network interface card receives a message from a network, an interrupt signal is generated to a CPU. In the CPU, upon detection of the interrupt signal, the operating system executes a dispatch routine for the interrupt, and reads a message from the network interface card to execute the required process. Generally, the network interface card or the operating system has a buffer for holding data before the message is read out and processed. A succession of messages which may arrive at the buffer of insufficient capacity may overflow and may be disposed of.
Especially with the increase in the transmission speed of the network, more and more messages come to be disposed of. Consider the procedure shown in FIG.
7
. The response messages
911
returned to the first device arrive in a great number in a short time. With the increase in the number of devices, therefore, the increased number of messages are disposed of. In the case where the first device is unable to receive all the response messages
911
within a predetermined time T from the transmission of the requesting message
910
, the first device retransmits the requesting message
910
. By repeating the retransmission of the requesting message
910
, substantially all the response messages
911
can be received.
If the predetermined time T is set excessively short, the requesting message
910
is undesirably retransmitted before it becomes necessary, resulting in a wasteful use of the band. The time required before completion of the procedure includes the retransmission intervals and the number of times the message is retransmitted. An increased number of response messages
911
that are disposed of and hence an increased number of retransmissions, therefore, leads to the problem of a lengthened time required for the procedure. Even in the case where the time before completion of the procedure is not a problem, the increased number of retransmissions increases the amount of information required to be transmitted for the procedure, thereby posing the problem of wasting the band of the network.
As described above, in the case where an ad hoc network is constructed based on Jpn. Pat. Appln. No. 07-87937 according to the prior art first above mentioned, the problem is that with the increase in the number of the devices constituting the network or the devices making up each group in the network, the number of the messages required for managing the device configuration or executing the procedure increases. At the same time, the band available for use by applications decreases or the time required before completion of the procedure lengthens beyond the practical application.
The second conventional approach will be described. In the case of communication between terminals using the conventional network including the rapidly-extending internet, it is necessary to determine an identifier such as an address in advance for specifying the destination device with which to communicate. An IP address and a host name for the internet are examples. In other words, communication has so far been impossible for the user without determining the IP address or the host name of the destination device.
On the other hand, the reference function of the Microsoft network proposed by Windows95 of Microsoft, U.S.A., for example, makes it possible for the user to determine the terminal connected with the Microsoft network simply by clicking an icon without any preparation, and thus to start the communication with the remote device simply by selecting the desired party. In the reference function of the Microsoft network, one processor included in the network acts as a reference server, and the terminals connected to the network notify the reference server of the presence thereof at the time of starting, while the presence of the other terminals can be determined by making inquiry of the server.
The reference function of the Microsoft network assumes that a terminal capable of communicating with a reference server can directly communicate with other terminals. Nevertheless, in the case where a network is constructed using a radio LAN, for example, the communicability with the reference server does not necessarily mean the communicability between terminals. What is called a hidden terminal may exist. In such a case, the reference function of the Microsoft network incapable of determining a hidden terminal poses the problem that the communication, though started without the knowledge of a hidden terminal, is impossible with Also, a portable terminal having a radio communication function may be moved without shutting down the operating system (OS). In such a case, the Microsoft network may take as long as several tens of minutes for detecting the impossibility of communication due to the movement. Thus the reference function of the Microsoft network cannot meet the ever-changing network environment with rapidity.
On the other hand, Jpn. Pat. Appln. No. 7-232459 discloses a method by which each terminal can determine whether or not communication is possible between terminals. According to this method, the identifiers of the terminals with which a local terminal can communicate are transmitted by each local terminal together with the identifier of the local terminal. As a result, each local terminal is in a position to determine whether the other terminals are communicable or not as well as the local terminal. In this method, however, all the terminals exchange information on communicable terminals. With the increas
Horiguchi Takeo
Ikegami Fumihiko
Iwamura Kazuaki
Kawamura Takuya
Matsubara Shinzo
Chin Wellington
Duong Frank
Kabushiki Kaisha Toshiba
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