Dissertation > Industrial Technology > Radio electronics, telecommunications technology > Communicate > Data communication > Data communications network

Researches and Simulations on MAC Layer Protocol of VMF Data Link

Author ZhangXiang
Tutor LuoZhiGang
School National University of Defense Science and Technology
Course Computer Science and Technology
Keywords data link VMF MAC variable timeslot TDMA
CLC TN919.2
Type Master's thesis
Year 2010
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Data link is the key technology in modern battle field. It connects both combat systems and weapon devices. VMF is one of the data links which has many advantages such as real-time, precision, reliability, and scalability. However, data link is such different from general commu-nication system that inter-connection and tactical cooperation becomes a critical problem once the type and scale of battle field has changed. Furthermore, the bandwidth resource in the data link system will become more limited even when much more weapons are appearing. In order to mostly use the VMF data link, it is essential to reasonably allocate the bandwidth resource in MAC layer.Currently, the allocation method is mainly TDMA algorithm. However, the TDMA algo-rithm whose timeslot length is fixed suffers from a waste of the remaining timeslot due to the constant of timeslot length. This paper presents a new TDMA algorithm for VMF data link whose message is short and flexibly changeable. It uses a variable timeslot and overcomes the problem of conventional TDMA algorithm. Therefore, it enhances the utility of timeslot in VMF data link. According to such a variability nature, we call our algorithm variable timeslot TDMA. Simulation technology has been widely used in evaluation of the data link system because of the advantages of considerable savings and the short test cycle. The paper evaluates TDMA algorithms in the MAC layer of data link by using simulation and gives the analysis of the simu-lation results.The main contributions of this paper are summarized as follows.First, this paper designs variable timeslot length TDMA algorithm based on the character of the message of VMF data link. It has several advantages: (1) it increases the number of valid timeslot because the node selection scheme reduces the number of delivering message; (2) it mostly saves the timeslots due to the changeable timeslot length.Second, the paper further improves the node selection scheme based on our variable time-slot TDMA and proposes a heuristic TDMA which enhances the usage of timeslot.Third, this paper theoreticaly compares fixed timeslot and variable timeslot length TDMA algorithm, and shows the validation and effectiveness of the proposed algorithms.Finally, we build simulation scenarios on the OMNET simulation platform. Then we com-pared the performance of our variable timeslot TDMA with the conventional fixed timeslot TDMA algorithm via an amount of simulation experiments. The experimental results show that the proposed algorithm outperforms the conventional algorithm.

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