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In DV-HOP algorithm, the average one-hop distance is calculated by using the centralized calculation and broken line replacing straight line method. Thismethod causeslocalization errors.In view of the localization errors,we propose an improved DV-HOP on weighted and distributed calculation method (WD-DVHOP) in this paper. In the WD-DVHOP, we replace the centralized and distributed calculation method by a weighted calculation method.The distance between unknown nodes and anchor nodes is calculated by a method, which the average one-hop distance of each anchor node multiplies by hops count between unknown nodes and anchor node.Simulation result shows that average localization error is reduced in the WD-DVHOP, in case of less anchor nodes and smaller communication radius.

To the problem of multiple dry-reed relays electromagnetic interference in application circuits, we present an effective method to reduce the electromagnetic interference in this paper. The method is alternating permutation matrix of dry-reed relays. The paper describes the cause of electromagnetic interference of dry-reed relays. Using the offset of electric polarity alternation principle, we put forward the method for reducing electromagnetic interference. The method is applied to a multi-functional physiotherapy instrument. By experiments, experimental result shows that the degree of electromagnetic interference is reduced along with the increase in the number of dry-reed relays.

Aiming at misjudgment formed by PIT (Point-In-triangulation Test) and position failure formed by edge effect in APIT algorithm, this paper introduces a multi-hop mechanism of DV-HOP algorithm and presents an APIT algorithm of based on DV-HOP multi-hop mechanism (AHMH-APIT). The AHMH-APIT algorithm uses DV-HOP multi-hop to compensate edge effect and anchor circle intersection region to replace triangulation, and uses weighted method to calculate the regional centroid. The paper simulated the AHMH-APIT algorithm by Matlab .The simulation result shows that, in the case of nodes being randomly distributed, compared with the APIT, all nodes can be positioned. Even if the number of anchor nodes and the communication radius is relatively small, unknown nodes can be positioned. And then the AHMH-APIT algorithm reduces average localization error and energy cost of communication.

To the disadvantages, such as high energy consumption and the energy consumption imbalance, we proposed an energy-efficient routing protocol on mobile sink (MSEERP) in this paper. In the MSEERP, the network is divided into several square virtual grids based on GAF, each grid is called a cluster, and the cluster head election method of GAF is improved. In addition, the MSEERP introduces a mobile sink in the network, the sink radios in limited number of hops and uses control moving strategy, namely the sink does not collect the information until it moves to a cluster with highest residual energy. We applied NS2 to evaluate its performance and analyze the simulation results by the energy model. Simulation results show that the MSEERP balances the energy consumption of the network, saves nodes energy and extends the network lifetime.