Electrical computers and digital processing systems: multicomput – Distributed data processing – Client/server
Reexamination Certificate
1998-11-20
2002-03-26
Maung, Zarni (Department: 2154)
Electrical computers and digital processing systems: multicomput
Distributed data processing
Client/server
C709S202000, C709S206000, C709S217000, C709S229000, C709S238000, C709S239000, C455S001000, C455S412100, C455S414200, C455S463000
Reexamination Certificate
active
06363412
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a wireless data transfer method and system and, in particular, to a communication system, such as an electronic mail system, which carries out sending/receiving digital data between a plurality of terminals through a wireless transmission network in a network computer system.
2. Description of the Related Art
A wide variety of communication systems have been proposed to send/receive digital data between a plurality of wireless terminals included in a wireless computer network which is controlled by a computer network.
Among others, one type of mail sending/receiving system has widely prevailed. In this connection, such mail sending/receiving systems will be described with reference to
FIGS. 1 and 2
.
FIG. 1
schematically shows an example of a conventional mail sending/receiving system.
FIG. 2
shows a procedure based on a protocol used for sending/receiving a mail or mail data in each conventional mail sending/receiving system.
At first, description will be directed to a first one of the conventional mail sending/receiving systems.
It is assumed that a mail (mail data) includes a mail header and a mail body. When a wireless terminal is used for an electronic mail system in a LAN (local area network) through a wireless communication network (for example, a mobile radio telephone network) a wireless terminal A
201
sends both a mail header and a mail body addressed to a wireless terminal B
203
to a mail server
202
(S
402
). Next, the mail server
202
stores the mail header and the mail body which are received (S
403
). The wireless terminal B
203
can connect to the mail server
202
in anytime, and when the wireless terminal B
203
determines that the mail header and/or the mail body addressed to it exist in the mail server
202
(S
404
, S
405
), it receives the mail header and/or the mail body from the mail server
202
(S
406
, S
407
). A wireless electronic mail receiving system which has been disclosed in Japanese Laid Open Publication No. HO8-139747 is similar in structure to the first conventional system.
It is a problem that, in a mail sending/receiving system as the first conventional system, a recipient of a mail cannot know contents of the mail until a wireless terminal B completes the reception of a mail header and a mail body of the mail. In other words, when a recipient wants to know contents of a mail, a wireless terminal B must receive both of a mail header and a mail body from the mail server. Even if the recipient does not need the mail or does not want to receive the mail, the mail header and the mail body of the mail are transferred to the wireless terminal B. Consequently, during the transfer, a wireless transmission network is used as transmission network and the recipient is to be charged according to the duration of use of the transmission network.
Such a problem becomes serious when a size of the mail header for each mail becomes small (for example, the size is about 10 through 100 bytes) and a size of the mail body for each mail becomes large. For example, a transmission time of about 14 minutes is needed for the transfer when the size of mail body is as long as 1 megabytes if transmission is carried out from a standard communication device which has a transmission rate of 9,600 bit per second (1 byte=8 bits). The above transmission time is measured on the assumption that disconnection neither takes place due to interference during the transmission time executed by the recipient nor any retry operation is repeated.
When disconnection occurs during reception of the mail body, the reception operation must be repeated by the recipient. A probability of occurrence of radio-frequency interference, which is one of the reasons for disconnection, is generally kept constant over the whole transfer time. However, during successive data transmission, as the data size becomes large, the probability of occurrence of the radio-frequency interference becomes high during transmission. As a result, the recipient often wastes money when the network is used for providing service of the network connection serve provider during a transmission time.
In a system, such as the first conventional system, when a sender sends a great deal of mail information to a lot of recipients in the form of an advertising direct mail, some or most of the recipients might neither need such mail information nor want to see the mail. This brings not only about a serious economical loss but also wastes a network resource.
On the contrary, if a mail body of about 1,000 through 5,000 bytes is received, a recipient does not suffer an economical loss since a cost for the reception of such a short mail body is as small as a cost for the reception of the mail header.
It is assumed that an account operation is carried out at every one of six seconds while a mail header and a mail body of 5,000 bytes are received for one second and five seconds, respectively. Under the circumstances, if a recipient receives only the mail header, the recipient pays for using the network for six seconds although he or she uses the network for one second. On the other hand, when the recipient receives both the mail header and the mail body, the recipient also pays for charges for using the network for six seconds. In the later case, the recipient does not pay for extra money, since it takes just six seconds to receive the mail header and the mail body.
Next, a second conventional system will be described with respect to the Figures of the first conventional system.
The second conventional system functions in the same way as the mail sending/receiving method shown in FIG.
1
. In the second conventional system, a wireless terminal A
201
sends a mail including a mail header and a mail body to a mail server
202
. Next, when a wireless terminal B
203
receives the mail, the wireless terminal B
203
receives only the mail header. If a user which received the mail header determines that the mail is necessary, the wireless terminal B
203
receives the remaining mail body.
According to the second conventional system, when the wireless terminal B
203
need not receive the mail body, it can instruct the mail server
202
to delete the mail body in the mail server
202
. Therefore, the second conventional system can reduce traffic in a transmission network between the mail server
202
and the wireless terminal B
203
by eliminating transferring unnecessary mail data between them. This is one of the merits in the second conventional system, as compared to the first conventional system. An electronic mail delivery system which has been disclosed in Japanese Laid-Open Publication No. HO1-236541 is similar to the second conventional system.
Here, for the sake of clarity, it is assumed that the wireless terminal A
201
sends a mail and the wireless terminal B
203
receives the mail in the above description. However, it is readily understood that the wireless terminal B
203
also can send a mail to the wireless terminal A
201
by exchanging functions of the above two terminals.
The mail sending/receiving system according to the second conventional system can overcome the problem in the first conventional system to some extent.
In the system, the wireless terminal B at first receives only a mail header on reception of the mail information from the mail server. Then, a recipient can determine whether or not a mail body is necessary for the recipient by referring to a size of the mail body, a title, and so on included in the mail header. Therefore, the recipient can select only necessary mail information to be received and may pay a reduced fee as compared to the first conventional system.
However, the second conventional system can not favorably cope with sending a large number of mails. Specifically, when a wireless terminal A simultaneously sends a plurality of destinations, such as over 1,000 terminals, mail information including a plurality of mails each of which includes a mail header and a mail body similar to one another al
Matsumoto Hidehiro
Niwa Yushi
Barot Bharat
Maung Zarni
Ostrolenk Faber Gerb & Soffen
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