Methods of fragmentation, transmission and copy control for file fixed size and changeable size in opportunistic network

Abstract

The invention discloses methods of fragmentation, transmission and copy control for a file fixed size and a file changeable size in an opportunistic network. In the invention, a large file is divided into fragmentations of the fixed size or the changeable size according to data transmission rate and connection duration of the opportunistic network; the transmission method is provided aiming at the fixed size fragmentation; fragmentation is performed through the fragmentation method provided by the invention and transmission is achieved independently; on the premise of guaranteeing transmission success rate, current network connection can be best utilized, so that transmission cost brought by fragmented control information is reduced, and besides transmission delay is lowered. The method of copy control provided by the invention has the advantages that rationalization of the copy control is realized by performing a priority ranking to transmission times, the situation that copies in one part of the fragmentation are too many while the copies in the other part of the fragmentation are few during copy transmission is avoided, the success rate of file transmission is improved and the transmission delay is lowered.

Description

technical field [0001] The invention relates to the technical field of file transmission, and more specifically relates to a method for controlling fragmentation, transmission and copying of files with fixed and variable sizes in an opportunistic network. Background technique [0002] As a means of information communication in a non-fully connected network environment, opportunistic networks originate from delay-tolerant networks. Opportunistic networks do not need to maintain end-to-end complete links, and can use node mobility to establish interruption-tolerant links for effective communication without pre-laying communication infrastructure. Typical application scenarios of opportunistic networks are mainly environments where fully connected networks cannot be established, such as interstellar network communications, network transmission in remote areas, wild animal tracking, portable device networking, vehicle communication networks, and military self-organizing networks...

AI Technical Summary

Problems solved by technology

This leads to an uncontrollable duration of the connection between nodes. For example, in the vehicle-mounted network, the meeting and separation of two driving vehicles are completed in a very short period of time, which is likely to not exceed 1 minute. In such a short period of time, they can transmit The amount of data is very limited. Larger files are interrupted during the transmission process. After the interruption, when they meet again, they still need to start the transmission from the beginning. The limitation of the connection duration leads to a very low transmission success rate.

[0008] (2) An error occurred during the transmission process

[0009] The opportunistic network mainly relies on wireless communication modules for transmission, such as Bluetooth, wifi, etc., and it is likely to communicate at a certain moving speed, and the signal itself may be relatively weak; in addition, because the frequency band used is a public frequency band, And the transmission environment is complex, so it is likely to be interfered by other communication equipment

The above two points lead to a high probability of packet loss and errors during the data transmission process. If an error is found after the data transmission is completed, the entire file needs to be resent, which will waste resources and reduce the transmission success rate.

[0010] (3) Insufficient cache space

This mechanism can easily lead to node cache pressure. If the data that needs to be relayed is large, the cache will not be enough, so we can only find other nodes for relay, which will cause the transmission delay to increase

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