Research On Some Issues In Minimum Hop Routing Wireless Sensor Networks

As the link between the subjective world of human and the physical world, wireless sensor networks have extensively application prospect, increase popular cause for concern, and become a hot subject of research in the fields of information technology. Wireless sensor networks is a kind of network for measurement and control, data acquisition and task distribution are the main work, and routing technology is one of the core technologies. The routing technology of wireless sensor networks depends on the network’s logic topology structure, which can be divided into two types such as the hierarchical topology structure and the planar topology structure according to the current achievements in the research. The maintaining of the hierarchical topology structure is complicated, so the hierarchical topology structure is suitable for the networks with stable physical topology structure. The maintaining of the planar topology structure is simple, so the planar topology structure is suitable for the networks with stable or dynamical physical topology structure. Minimum hop routing wireless sensor networks is a typical representative of planar logic topology structure networks, it’s logic topology structure supporting the data sinking is mainly the minimum hop gradient field, which not only can adapt the direction of the data sinking, but also has the potential advantages such as the shortest path, the least overheads and the least time delay. But there are some drawbacks in traditional minimum hop routing wireless sensor networks, which hinder the potential advantages to bring into full play, and influence the effectiveness of practical application. In this paper, the wireless sensor network is made further improvements, and the main research content and research achievements are as follows.1) By analysis of the operation model of minimum hop routing wireless sensor networks with the help of geometric structure theory, the characteristics of the logic topology structure, inquiring packet’s disseminating model and data packet’s propagating model in the aspect of geometric structure, and the characteristics of operating model in minimum hop routing wireless sensor networks are provisionally revealed.2) On the basis of geometric structure analysis, the operating characteristics of minimum hop routing wireless sensor networks are further revealed through simulating, the conception of gradient neighbor node or fine-grain gradient value is presented, the relation between the number of gradient neighbor nodes and the distance from a node to the relevant gradient level boundary is found. The propagating characteristics of inquiring packet and data packet are further brought to light, the drawbacks such as the short stable cycle, the uneven data stream, and the imbalanced transmitted traffic are discovered, and the methods of low cost information extracting based on piggyback are discussed, these pointed out the direction to improve the traditional minimum hop routing wireless sensor networks.3) The distance estimating method based on the information of gradient neighbor node (DV-GNN) and the distance estimating method based on fine-grain gradient value (DV-FGI) are presented, these methods can increase the measurement precision from effective radio-range to the space between nodes, compared with DV-hop algorithm, and these two distance estimating methods give network node the capability of distinguish each other. Compared with DV-hop algorithm, the DV-GNN method may increase a little inquiring overhead, but the DV-FGI only increases some computing overhead rather than inquiring overhead, which can keep the energy efficiency to the level of DV-hop algorithm.4) The control strategy of the gradient level width of minimum hop gradient field in minimum hop routing wireless sensor networks is presented. Making use of the relation between the number of gradient neighbor node and the distance from the node to the gradient level boundary, the width of gradient level is controlled based on the information of gradient neighbor node, which leads to the gradient level width narrower than the node’s effective radio range, and achieves the goal of prolonging the minimum-hop-gradient-field’s stable period, improving the data-sinking reliability, and balancing the sinking data stream.5) The dynamically adjusting strategy of minimum hop gradient field is given. By adjusting the minimum hop gradient field based on the number of source-end neighbor, destination-end neighbor, interleaved-source-end neighbor and interleaved-destination-end neighbor, the stable cycle of minimum hop gradient field can be extended, the reliability of data sinking can be enhanced, and the massive energy dissipation and time overhead resulting from rebuilding a new minimum hop gradient field can be reduced. The dynamically adjusting strategy of minimum hop gradient field has better sound effects in minimum hop routing wireless sensor networks whose physical topology structure changes with a lower speed.6) The adaptive controlling strategy of data-packet replica based on prediction is presented. In minimum hop routing wireless sensor networks, the data packet is repeatedly transferred along multi-path, there exist multiple data-packet replicas, and multi-replica is good for the data-sinking reliability, but it not only leads to massive energy dissipation but also may result in poorer combination property of data sinking. By controlling the data-packet replica to the necessary and the lowest level, the data-sinking stream and the transferring traffic can be balanced, and the combination properties of network can be optimized.In this paper, the behavior characteristics of minimum hop routing wireless sensor networks were conferred, and some drawbacks of the traditional minimum hop routing wireless sensor networks were improved. We hope that the applying effect of minimum hop routing wireless sensor networks in practical networks can be further improved through these works.