| Wireless sensor network is a network that integrates information world and physical world.It relies on nodes within the monitoring range to cooperatively collect,process and transmit data information.It has changed the way of interaction between human and nature,greatly expanded the function of the network and the ability of human to understand the world,also,It has been highly valued by scholars at home and abroad.As the key research content of wireless sensor network,routing protocol is of great value for continuous optimization and improvement.TORA is an on-demand routing protocol,which introduces a height mechanism for link selection.It can form one or more effective links between the source node and the destination node.With good robustness and high efficiency,it is widely used in various fields.But there are also problems such as uneven network load,high network overhead.To solve the above problems,based on the in-depth study of classic TORA,this paper proposes an optimization protocol(TORA-p)which combines load balancing strategy and low overhead strategy.It defines the parameter of link availability through the node idle degree calculated by the network MAC layer information.This parameter is taken as the priority reference index to optimize the next hop selection of nodes and disperse the network data flow.At the same time,the network change rate is defined by taking the node link change score within the BEACON packet transmission interval in the IMEP response mechanism as the parameter.According to the network rate of change,the maximum number of retransmissions of OBM packets can be adjusted to reduce the unnecessary routing maintenance cost caused by link fault detection errors.In order to verify the superiority of TORA-p in this paper,a simulation comparison was made on the TrueTime2.0 platform.Firstly,two indexes,routing overhead and node energy balance,were selected to verify the feasibility and effectiveness of the low-overhead strategy and the load balancing strategy.Meanwhile,the results show that the optimized TORA-p is more energy balanced than other algorithms,and the overall network overhead was lower.After that,the simulation comparison was made between the TORA-p,TORA,DSR and AODV to test the performance of the end-to-end average delay,packet delivery rate and routing overhead when the packet rate and node movement speed change respectively.Last but not least,the network lifetime index was selected to test each protocol.The results show that TORA-p has more advantages in reducing delay,improving packet delivery rate,reducing routing overhead and energy consumption,improving network reliability and extending network lifetime.Finally,we carried out the hardware experiment through the Crossbow TelosB Mote TPR2420.We took the collection and transmission of temperature,humidity and lighting as an example to discuss the realization of TORA-p protocol based on TelosB.Then we tested packet loss rate fordifferent packets' number and period of sending packets to evaluate their routing performance.The results show that TORA-p is better and more reliable.Last but not least,According to the WSN node energy consumption model,we measured the energy consumption of TORA and TORA-p under the change of network running time.The results show that TORA-p protocol consumes less energy than TORA protocol. |
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