The Implementation Of Multi-channel TDMA Protocol Based On Programmable Network Card

With the rapid development of information technology, people are more and more concerned about Ad hoc network because of its self-organizing, mobility, and characteristics of independent of the fixed facilities.In Ad hoc network system, Media Access Control protocol, which is located above the physical layer, determines the order and time of the nodes in the network can access channel, its main function is to ensure fairness and effective resource sharing, it is an important component part of the Ad hoc network protocol.At present, MAC protocols based on Ad hoc network are mainly competition class, competitioncategoryof MACagreement will lead to the inequity of the allocation of resources among nodes and the long delay problems and so on. Competitioncategoryof MACagreement can’t Meet the requirements of real-time transmission while there are lots of competitions, but TDMA protocols based on the distribution can effectively solve these problems.This paper mainly studies the different types of TDMA MAC protocol, and chose three classic protocol respectively from the fixed allocation TDMA, dynamic distribution of TDMA and mixed type of MAC protocol for specific analysis. We proposed a channel variable MAC protocol based on dynamic slot allocation TDMA.The slot allocation algorithm we proposed allocate slots of next time-frame through analyzing the workload of last time-frame, it can realize on-demand allocation. Compare dynamic slot allocation algorithm with traditional fixed time slot allocation TDMA protocol, we can find that network throughput has increased significantly. At the same time, the protocol we proposed can realize dynamic channel selection, we can evaluate channels’ conditions every time-frame and selectively switch channel. In this paper, we proposed two kind of multi-channel algorithm, one is greedy multi-channel algorithm based on the consideration of channel noise, we choose the channel of the lowest noise at the beginning of every time-frame to execute the data transmission of this time-frame. However, considering that there may be multi network selecting channel at the same time, on the channel of lowest noise may have multi network transmitting, this can lead to the increase of competition and causing the increasement of delay. Therefore, we proposed multi-channel algorithm based on Q learning, which can select channel according to the historical channel circumstance.In this paper, we completed the system implementation through the combination of programmable wireless network card and USRP. The implementation processMainly divided intoTD implementation, time synchronization, multi-channel algorithm implementation and dynamic time slot allocation algorithm implementation. We introduced the above parts of system implementations in details, and validated respectively.