TDMA-Based Non-Interference Time Slot Allocation Algorithms For Underwater Acoustic Sensor Networks

With the development of marine resources,stabilized and efficient underwater wireless information transmission has been under investigation.Compared to wireless channel,the underwater acoustic channels known to have lower bandwidth,long signal transmission delay and attenuated transmission.Therefore,the application of underwater acoustic sensor networks in ocean environment is inevitable in the development of marine information engineering.Underwater acoustic sensor networks are still in the development stage and hence,the design of Media Access Control(MAC)at the link layer is considered to be a hot research topic.Consequently,this thesis takes underwater linear multi-hop network as the application object and studies the non-interference time slot allocation algorithm based on time division protocol,so as to improve network throughput and energy efficiency and extend network life cycle.The main research work and contributions of this thesis lie in the following aspects:(1)Based on the signal propagation characteristics in the underwater acoustic channel and marine environmental noise characteristics,the signal-to-noise interference ratio in the network data transmission is deduced The communication range and interference range are defined through numerical simulation.The normalized maximum communication distance is 1,then the interference range is 2.This conclusion is used as the design basis of the slot allocation algorithm.(2)To improve the spatial multiplexing rate,a link-based slot allocation algorithm is proposed.This algorithm takes the packet transmission link as the minimum scheduling unit,establishes the link interference relation based on the signal interference range,the time slots occupied by each link are allocated reasonably to minimize the time frame cycle.Theoretical analysis shows that the throughput upper bound of the slot allocation algorithm is slightly lower than the theoretical upper bound 1/2 and the lower bound is 3/8.(3)In order to further improve the spatial multiplexing rate,this paper integrates Physical layer Network Coding(PNC)into the link slot allocation algorithm and proposes a PNC-assisted slot allocation algorithm,compared with the time slot allocation algorithm based on link,the time slot allocation algorithm assisted by PNC takes advantage of the limited "permissible interference" feature of PNC,further improves the throughput of the network and theoretical analysis proves that the algorithm can reach the theoretical upper bound throughput 1/2.