Layer Based and Energy-Balanced Clustering Protocol for Wireless Sensor Network

Transcription

1 Sensors & Transducers 2013 by IFSA Layer Based and nergy-balanced Clusterng Protocol for Wreless Sensor Network 1 Yu HU, 2 Shu HAN 1 Measurng and Controllng Technology Insttute, Tayuan Unversty of Technology, Tayuan , Chna 2 Measurng and Controllng Technology Insttute, Tayuan Unversty of Technology, Tayuan , Chna -mal: hanshuthehero@gmal.com, huyutyut@163.com Receved: 13 September 2013 /Accepted: 25 October 2013 /Publshed: 30 November 2013 Abstract: Herarchcal routng algorthm s the most mportant method for prolongng lfetme of wreless sensor networks, whch can not only decrease the energy consumpton of the nodes, but also balance the energy dsspaton of the entre network. Therefore, ths paper proposes a new layer based and energy-balanced clusterng protocol whch was compacted energy-aware and energy-consumpton-balanced. In the lower layer of the protocol, the optmal cluster of all nodes usng partcle swarm optmzaton algorthm was realzed. And n the upper layer, the chef-cluster-head, whch was responsble for collectng, aggregatng the data of all cluster heads and sendng the fused data to the base staton, was selected. Smulaton results demonstrated that the protocol can effcently decrease the dead speed of the nodes and prolong the network lfetme. Copyrght 2013 IFSA. Keywords: nergy equlbrum, Wreless sensor network (WSN), PSO, Asynchronous clusterng. 1. Introducton Snce wreless sensor networks (WSN) [1] nodes are usually deployed n naccessble areas and usually powered by very lmted mcro-power battery, t s almost mpossble to renewal the battery of the nodes agan. Therefore, t s vtal to mprove the energy effcency of nodes to extend the network lfetme of a wreless sensor network routng. In order to extend the network lfetme by savng nodes' energy and balancng energy consumpton, ths paper proposed usng the partcle swarm to help balancng energy consumpton n wreless sensor networks from the master and vce cluster-head clusterng routng protocol (PSO-MV), whch chooses two of the best nodes as the cluster-head nodes at frst, namely the master cluster-head (MCH) and the vce cluster-head (VCH), through partcle swarm algorthm. Then, MCH and VCH work n phase. MCH s responsble for collectng nformaton from cluster member nodes and sendng the fused data to the nearest VCH. Intercluster routngs are establshed among VCH, whch communcate wth the base staton n the combnatory method of sngle-way and mult-way. 2. Partcle Swarm Optmzaton (PSO) The PSO [2, 3] s ntalzed to a group of random partcles, and then fnd the optmal soluton by teraton. All the partcles have to be optmzed by a decson of the ftness functon, each partcle has a speed to determne the drecton of ts flght and dstance, and partcles wll follow the best partcle n 148 Artcle number P_1474

2 the soluton space seekng for the next best locaton. Durng teraton, the partcles update themselves by trackng the two extremes. The frst one s, by the partcle tself, to fnd the optmal soluton P d ; the other extreme s the most optmal soluton of the current populaton P gd. The updatng formulas [4] as follows: vd(t 1) wvd(t) c1r 1( pd x d(t) ) + cr(p 2 2 gd xd( t) ) + = + + (1) x d ( t + 1) = xd ( t ) + vd ( t + 1) (2) In ths formula, t stands for tme of Iteratons; v d s the speed of partcle ; x d s the locaton of partcle ; r 1 and r 2 are random numbers between 0~1; c 1 and c 2 are acceleratng factors; w s weghtng coeffcent. 3. Algorthm Revew PSO-MV clusters base on clusterng routng, ncludng the stages of generaton and data transferrng Cluster Formaton Intalze the Cluster-Heads Selected canddate cluster-head nodes compose the set of ntal cluster, set the energy threshold λ : N λ = / N (3) = 1 The current resdual energy s greater than the threshold value as canddate cluster-head nodes. Only the canddate cluster heads are possble to become the current round of the cluster. stablshed S wat represents the set of canddate clusters, then: S wat = { n > λ} (4) where n s the number of nodes n the network; stands for the node's current resdual energy Informaton Gatherng Stage of Cluster Members Nodes wll send the remanng energy, poston and ID numbers and other nformaton of the members to the base staton through the canddate cluster. Then each neghborng canddate clusterhead node obtans the ID, locaton and resdual energy, and more PSO-Based Optmzaton of Cluster Head lecton Phase Usng PSO algorthm to optmze the choce of master-slave cluster-head s the core of ths algorthm, the algorthm follows these steps: Step1: Intalze Q partcles: randomly ntalze swarm cluster head's X and V from canddate partcle. Step2: Calculate the adaptve value of every partcle cost by usng formula (5). Step3: Determne the optmal soluton for each ndvdual partcle and populaton optmal soluton. Step4: Update the speed and locaton of partcles by formula (1) and (2). Step5: Repeat the step 2~4 untl meet pre-defned teratons, then choose the most optmal soluton and the second-best nterpreted as the man from the cluster head Optmal Cluster Formaton Stage After the stage of selectng of PSO optmzng, the base staton broadcast the most optmal set of cluster heads and cluster structure out. Whle each non-cluster head node chooses to jon whch of the cluster based on the receved sgnal strength, they send ther remanng energy, ther locaton and other nformaton to the cluster head nodes. Then, t wated for the cluster head node to be assgned TDMA tme slots to avod data conflcts Data Transfer Stage Data Transfer wthn the Cluster After the man cluster head node assgnng TDMA tme slot, the cluster member nodes send packets to the cluster head node n the correspondng tme slot. And wthout the delvery tme, the transcever devce could be turned off and turn nto sleep mode to reduce the consumpton Data Transfer Between the Clusters The man cluster head node wll send the data fuson of the members of nodes to the nearest slave cluster heads (ncludng base staton) after recevng the data. In order to overcome LACH protocol whch causes some nodes to de untmely n a way of sngle hop, the routng between clusters takes the way of combnng sngle hop and mult-hop. Settng the dstance between cluster head node and Snk nodes as d, set the lmt value of d 0, 1) If d d 0, a sngle hop from the cluster head n the form of drect communcaton wth the Snk node; 2) If d> d 0, usng PSO to search the optmal path n the upper level to acheve plane data transmsson between clusters and reduce energy consumpton to extend network lfe cycle. 149

3 3.3. Improved Ftness Functon For wreless sensor network routng optmzaton model characterstcs and goals, the followng factors should be responsble for the ftness functon: 1) cluster head energy ratng factor f 1 : the current canddate node s remanng energy; 2) cluster head from the evaluaton factor f 2 : manly consderng the dstance between the remanng members of the cluster nodes and ths node, the smaller the average dstance, the better for the node beng the cluster; 3) the equlbrum level of resdual energy evaluaton factor f 3 : the more balanced level of resdual energy n the rest of the network nodes, the more easly for t to avod the network empty; 4) the dstance between base statons evaluaton factor f 4. The ftness functon s defned: cost = α 1 f 1+ α 2 f 2 + α3 f 3 + α 4 f 4 (5) f = / (6) 1 0 f = dn (, CH)/ C ( ) 2 j C() k= 12,,.., k f = ( µ ) 3 j j C() { } 2 (7) (8) f4 = max d( BS, CH ) / d( BS, NC ) (9) s the current resdual energy partcle, CH stands for the frst canddate cluster head, C() means the members of the nodes; d (n j,ch ) s the dstance between members of the node j to the canddate cluster head node CH, BS s the representaton of the base staton, NC stands for the network center coordnates: α 1,α 2,α 3,α 4 are weght coeffcents for each evaluaton factor, α 1 +α 2 +α 3 +α 4 =1, so the smaller the ftness functon, the more ftness to be a cluster head. 4. nergy Consumpton Model for Wreless Communcaton In ths paper, we wll use that energy consumpton model for wreless communcaton mentoned n paper [5, 6]. Wreless communcaton module has the functon of power controllng: t can use the mnmum energy to send data to the recever, each k bt of nformaton sent to the dstance d wll the amount of energy of: ( d d 0) ( d d 0) elec k + fs k d 2 < Tx ( k, d ) = elec k + mp k d 4 (10) where, k stands for the dspatchng bnary dgts, d s the sendng dstance, d 0 s the threshold of sendng dstance. d 0 = fs mp (11) elec s the coeffcent of RF energy consumpton, ts unt s nj/bt. fs, mp s the nergy coeffcent of the amplfer crcut, unt s pj/bt/m 2. If the dstance s less than d 0, power amplfer wll use the free space loss model; f the dstance s more than d 0, t wll use mult-path fadng model. nergy consumpton [7, 8] of recevng data s: ( k ) = elec k (12) Rx So the energy consumpton for one k bt data transferrng from node n to n j s: ( k) = R( k) T( k, ) (13), j + d 5. Network Smulaton and Protocol Analyss We wll use the model of wreless communcaton mentoned n secton four. In the smulaton, wreless sensor networks composed by 100 nodes, nodes randomly dstrbuted n a 100 m 100 m area. Ths paper wll use Matlab to make the smulaton. The man parameters of the wreless sensor network model are: the ntal energy for each node s 0.5 J, populaton scale s: Q=30, c 1 =c 2 = 2, w=0.9. The rand wll be gven randomly durng the processng. valuaton factors: α 1 =0.25, α 2 =0.3, α 3 =0.25, α 4 =0.2. To test the effectveness of the algorthm, when emulatonal base staton locates n the center of montorng area: (50,50) and the area lmt (50,100), t wll runnng the states of the remanng numbers of nodes after Master-slave cluster head algorthm and LACH protocol. The comparson result as the Fg. 1. The Fg. 1 stands for the comparson result of Network lfetme when the base staton locates n (50,100) and (50,50) as runnng PSO-MV, LACH and PSO. The result shows as followng: overall, whether the base staton s located n the montorng of the regonal center or edge of the area after the mplementaton of PSO-MV algorthm, the tme that from startng the operaton of the network to the death of the frst node s longer than ether the PSO or LACH, the network lfetme has been renewed. Ths algorthm s due to the frst electons n the cluster usng PSO fully consdered the balance of the remanng resdual energy level, the average dstance between neghborng node and canddate cluster head node and so on. To some degree, the better energy balance and the dvson of labor n the data transmsson phase help the network avodng some nodes to de for the heavy load. The Table 1 lsts the rounds of dyng for the frst node, the rest half nodes, and 80 % of nodes. 150

4 more balanced and compact, and greatly extends the network cluster head electon cycle, thus savng more energy, so t balanced the energy of the network at the end, to extend the network cycle. Fg. 1 (a). Remanng nodes when base staton locate n (50,100). Fg. 2. The total energy consumpton of the network. 6. Conclusons Fg. 1 (b). Remanng nodes when base staton locate n (50,50). 1 st node dyng half of nodes dyng 80 % of the nodes dyng Table 1. Lfetme comparson. Base staton at (50,100) Base staton at (50,100) LACH PSO PSO-MV LACH PSO PSO-MV The Fg. 2 shows the total energy consumpton of the LACH, PSO and PSO-MV protocol agreement n the network when base staton locate n (50,50). The fgure shows that the proposed PSO-MV protocol s to be sgnfcantly lower than the total energy consumpton of LACH and the PSO agreement, ndcatng that although the PSO-MV protocol whch s used n the clusterng process of two-partcle swarm cluster head needs more tme consumng. But ths Algorthm makes the network Ths paper proposed the double cluster head based on PSO clusterng routng algorthm PSO-MV. Through smulaton experments, the result proves that t has good performance. Algorthm optmzes energy consumpton by dstrbutng the labor for cluster head node and subordnate ones, balancng energy consumpton to extend the network lfe cycle effects. However, the man focus of ths paper s to extend the network lfe cycle. Therefore, the choce of parameters of the algorthm s not consdered deeper. Acknowledgement Ths work was fnancally supported by the Shanx Natural Scence Foundaton ( ). References [1]. S. Radosavac, J. S. Baras, Applcaton of sequental detecton schemes for obtanng performance bounds of greedy users n the I MAC, I Communcaton Magazne, Specal Issue on Securty n Moble Ad Hoc and Sensor Networks, Vol. 46, No. 2, February 2008, pp [2]. Changjang Jang, Weren Sh, nergy-effcent clusterng protocol for WSN based on PSO, Computer ngneerng, Vol. 36, Issue 8, 2010, pp [3]. Jennfer Yck, Bswanath Mukherjee, Dpak Ghosal, Wreless sensor network survey, Computer Networks, Vol. 52, Issue 12, 2008, pp [4]. Xngzhen Ba, Shu L, Juan Xu, Moble Sensor Deployment Optmzaton for k-coverage n Wreless Sensor Networks wth a Lmted Moblty Model, IT Techncal Revew, Vol. 27, Issue 2, 2010, pp

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