【導讀】由于傳感器能量資源的有限,他們中的每一個都應該減少能源消。傳感器網(wǎng)絡的構建一種高效率能源樹結構,而無需定位信息的節(jié)點。守恒是由傳輸功率控制完成的。節(jié)點也提出了協(xié)議。仿真結果表明,我們的分布式協(xié)議可以達到類似集中算法的。能量節(jié)點的電池,部署在數(shù)百到成千上萬的無線傳感器網(wǎng)絡。除此之外,補充能量的電池更換和充電幾百節(jié)點上的傳。完全取決于耐久性的電池。有四種主要的報告模式的傳感器網(wǎng)絡:事件驅動、隊列驅動、期刊、查詢和混合的報告。在事件驅動模型,節(jié)點報告接收器,同時。報告遙感一些事件,例如火災或水災而敲響了警鐘。資料相結合的方法,稱。絡中的重要研究問題。當前的理想發(fā)射功率，為每個相鄰的節(jié)點。然而,LEACH需要全球的傳感器網(wǎng)絡的知識，并且假定每個節(jié)點接近BS。節(jié)控制網(wǎng)絡拓撲結構可以延長壽命及提高無線傳感器網(wǎng)絡的能力。

　　

【正文】 ng minimum transmission power level (Pmin = 0 here) and a connected tree topology of the whole work is formed among different group of nodes using an effective power level (PTx), where (Pmin=0)PTx (Pmax=3). The different phases of this distributed protocol are described as follows. . Construction phase As soon as the nodes are deployed on the work, the sink initiates the construction phase by broadcasting a construct packet with minimum transmission power (Pmin = 0) to get connected with its immediate neighbors, as shown in Fig. 4(a). The format of the construct packet is shown in Fig. 3 and the parameters of the packet are initialized as: SID = Sink’s ID, PGID = Sink’s ID, NEL = Sink’s power level, LHC = 0, GHC = 0, PGPL = 0. Since, sink node generally receives the data, its PGPL is assigned to 0, which is different for other parent gateways of the work. Upon receiving the construct packet, the neighbors of the sink within its minimum transmission power range (Pmin = 0), scan all parameters of the packet. They wait for the random time Wi, as defined in Eq. (1), and get connected with the sink. Let Ni, be the number of neighbors of ith node, out of N nodes in the work. Upon receiving a construct packet, the waiting time of the ith node can be considered as: (1) where αi is a small random number patible with CSMACA mechanism [22]. Then, each of them rebroadcasts the construct packet using the same minimum power level Pmin = 0 to their neighbors with necessary increments to the parameters of the construct packet and waits for time Ti units, as defined in Eq. (2). (2) where Ei is the current energy level of ith node and βi is a very small random number such that βi . Fig. 3. Format of the construct packet. In order to avoid the packet collision among group of nodes in a dense work, we propose that the sink also waits for Ti units after broadcasting the construct packet and then goes to the information phase, as described in Section . It is to be noted that sink must be within at least one of the sensor node’s minimum or maximum transmission power range. However, if the sink does not find any neighbor with Pmin = 0, it goes to the information phase to construct the link with its neighbors, after the waiting time Ti has elapsed (Table 2 and Table 3). Table 2. Construction phase algorithm for the sink and any node of the work ALGORITHM 1: Construction Phase For the Sink: 1. Initialize: Parameters and Local Hop Count (LHC)=0。 2. Set: Transmission power Pmin=0。 3. Broadcast the Construct packet。 4. Wait for Ti units。 5. Go to Information Phase。 For any node(i): 1. If: (Receives Construct packet) 2. { 3. Waits for Wi units。 4. Scan LHC of each received packets。 5. Get connected with the sender whose LHC has least value。 6. Set: Pmin=0。 7. Increment: LHC by 1 in the Construct packet。 8. Broadcast the Construct packet。 9. Wait for Ti units。 10. Go to Information Phase。 11. } 12. Else: Wait for T = (Wi + Ti) units。 13. Go to Maintenance Phase, as described in Section (C). Table 3. Information phase algorithm for both Sender and Receiver ALGORITHM 2: Information Phase For any Sender(i): 1. If: (Receives Construct packet) 2. { 3. Copy value of PGID and GHC from the Construct packet。 4. Increment: Value of GHC by 1。 5. Initialize: All parameters of the Inform packet。 6. Set: Transmission power Pmax = 3。 7. Broadcast the Inform packet。 8. } 9. Else: Go to Maintenance Phase, as described in Section (C)。 For any Receiver(j): 1. If: (Receives Inform packet) 2. { 3. Wait for random time patible to CSMACA mechanism。 4. Estimate physical distance between itself and each senders。 5. Estimate effective transmission power (PTx(ij)) between the closest sender and itself。 6. Set: Value of PTx(ij) as PGPL in the Construct packet。 7. Copy value of GHC from the Inform packet to the respective field of the Construct packet。 8. Initialize: PGID as its own ID。 9. Go to Construction Phase。 10. } 11. Else: Go to Maintenance Phase, as described in Section (C). Upon receiving the construct packets, the nodes scan all parameters in it and consider the node having least LHC as its source. The receiver nodes wait for Wi units, get connected with its source and then follow the same procedure, as described above. This process continues till a node does not receive any construct packet further and the first tree topology is constructed among the nodes of a group, as shown in Fig. 4(b) with sink as the root and other nodes within minimum transmission power level to it as the children of the sink. Since, we assume that there are connectivity holes among different group of nodes or some nodes are unable to construct link using Pmin, the construction phase is terminated after a finite interval of time. The next group of tree topology is formed after the information phase is executed. It is to be noted that the construct packet is always transmitted using minimum transmission power level and each time LHC is incremented by 1, when it hops from one node to another. In a group, it could be possible that some nodes might have received the same construct packets from other neighbors, too. Then, how a node decides its own source node? We have discussed this part of the problem in the maintenance phase, as described in Section (A). Fig. 4. (a) Randomly distributed sensor nodes over an area. (b) Construction of the first tree topology. . Information phase The purpose of this phase is to construct a distributed tree topology in the whole work, using most effective power level among different group of nodes. It is acplished by broadcasting the inform packets using maximum transmission power level (Pmax = 3). The format of the