Adaptive Energy and Location Aware Routing in Wireless Sensor Network

Transcription

1 Adaptve Energy and Locaton Aware Routng n Wreless Sensor Network Hong Fu 1,1, Xaomng Wang 1, Yngshu L 1 Department of Computer Scence, Shaanx Normal Unversty, X an, Chna, fuhong433@gmal.com {wangxmsnnu@hotmal.cn} Department of Computer Scence, Georga State Unversty, Atlanta, USA, yl@cs.gsu.edu Abstract. Ths paper proposes a novel routng algorthm called AELAR for wreless sensor networks to meet QoS requrements: energy conservaton and data delay reducton. Frstly, we propose a novel method of dvdng routng request zone and construct a select equaton whch can enlarge the energy awareness as network tme goes on. We make the routng request zone and factors n select equaton changed automatcally. Smulaton results show that AELAR outperforms tradtonal algorthms n the performance of network lfetme, utlzaton and consumpton balancng of energy and data delay. Keywords: Wreless sensor networks, Energy effcent routng, Dstance level 1 Introducton Sensor nodes n Wreless sensor networks (WSNs have resource constrants whch nclude lmted energy, processng capacty, storage, communcaton range and bandwdth [1]. These unque features have rased specal problems that must be solved whle desgnng routng protocols. For nstance, n some applcatons, routng algorthms must meet QoS requrements such as energy conservaton and data delay reducton. Some routng algorthms (e.g., [], [3], [4] lmt the routng search to request zones to reduce the cost of floodng. Geographcal routngs (e.g., [5], [6] use greedy forwardng mechansms to forward packets. GPSR [7] s such an effcent, classc algorthm. But GPSR s based on a sngle metrc. GEAR [8] uses energy aware metrc, together wth geographcal nformaton, to make routng decsons. However, the energy balancng strategy n GEAR ncreases the average path length. Wth the progress on the semconductor technology, wreless sensors capabltes of computaton, storage may not be lmtatons n future. However, how to consume energy effcently s stll one of the most challengng problems n WSNs researches [9]. The man goals of the research presented n ths paper are to: Prolong the network lfetme of WSN to delver more packets; Balance the energy consumpton of nodes and acheve energy conservaton; 1 Ths work was supported by NSFC (607734, , the Key proect of Chnese Mnstry of Educaton under Grant ( and the Scentfc Research Foundaton of State Educaton Mnstry for the Returned Overseas Chnese Scholars.

2 Fnd the routng path as short as possble to reduce data delay. The rest of the paper s organzed as follows: Secton descrbes the network system. Secton 3 presents our proposed algorthm. Secton 4 demonstrates the effectveness of AELAR va smulatons. Fnally, secton 5 gves concludng remarks. The Network System Model To smple the queston, we assume that all sensors are homogeneous. They have the same ablty of communcaton and the radus of communcaton s r. They know ther neghbors and ther own locaton nformaton by locaton servces, e.g., Ad hoc Postonng System wth Angle of Arrval [10]. We also assume that there s only one snk n the WSN. Besdes, we gve the follow defnton for our research: Dstance level. For a gven sensor node n, let d d s the dstance from node n to the snk, the dstance level of node n, d l, s defned as d d l d / m =. (1 Where, m s the dstance level dvdng standard. It can be determned by specal applcatons. The dstance level can ndrectly ndcate the dstance from the snk. 3 Adaptve Energy and Locaton Aware Routng In ths secton, we present a novel method of dvdng routng request zone and construct a select equaton whch can be adusted accordng to nodes dstance levels. 3.1 Ellpse-shape Routng Request Zone and Densty Self-adaptaton We employ the vrtual coordnates [11] to dentfy the routng request zone. In Fg. 1(a, gven the node I, lettng O be the orgn, the vrtual coordnates of a neghborng node (e.g. J, (x, y, can be calculated by the followng equatons: x ' = cos( θ ( x x + sn( θ ( y y ; y y θ = arctan(. y ' = cos( θ ( y y sn( θ ( x x x x In AELAR, we defne the routng request zone as the overlap area of an ellptc regon and a dsk. In fg.1 (b, the shallow area shows the proposed routng request zones. Lettng d be the dstance form node I to node J, the node I can use (3 to learn whether a neghborng node locates n ts routng request zone. ( x' a a ( y' + b 1 From Fg.1 (b, we can fnd that ellpse parameter a and b (especally, b have great mpact on the sze of routng request zone. To smplfy the dscusson, we assgn the and d r. ( (3

3 (a Vrtual coordnate of node J (b Dfferent value of b for dfferent nodes Fg. 1. Vrtual coordnate and ellpse-shape routng request zone of a node value of a as transmsson radus r. However, we must take serously the value of b because t has the most mportant effect on the sze of routng request zone. Accordng to geometrc knowledge, the value of y of the neghborng nodes whch are closer from the snk than the node I s lmted by the nequalty: y' rd d r. (4 Where, d d s the dstance from the node I to the snk. We hope that the nodes whch have long dstance from the snk can forward data packets as soon as possble and the nodes near the snk have more optons to choose the next hop, so that the nodes near the snk can better balance the energy consumpton. To make the node I can adust the value of b accordng to ts locaton, we make node I determne the value of b as: b = δ r d d r. (5 Where,δ s determned by the dstance level and the transmsson radus of each node. Only the neghborng nodes that locate n the routng request zone are consdered to be next-hop canddates n AELAR. 3. The Select Equaton To select an approprate node as the next hop for forwardng data packets, AELAR strkes a balance between resdual energy and dstance metrcs. We use the natural logarthm functon for resdual energy level to enlarge the resdual energy dfference among neghborng nodes. Lettng e r be the resdual energy of a neghborng node J and e be the ntal energy of node I. Then, the node J s select factor f s defned as α {( e / e ( d d } β f = ln /. (6 r In above select equaton, α and β are the weght factors of energy consumpton rato and dstance rato. In AELAR, we make the nodes adust ther weght factors automatcally accordng to ther dstance levels. In WSNs, the nodes closer to the snk usually carry out more forward tasks. We hope these nodes consder more dstance d d

4 (a Number of packets delvered to the snk (b Energy utlzaton rado of WSN (c The energy standard devaton (d Average hops of searched paths Fg.. Smulaton results for evaluatng the performance of AELAR factor so that the total energy consumpton s lower. AELAR selects the neghborng node that not only locates n the routng request zone but also has the greatest value of f as the next hop. The energy effect on the above equaton wll drastcally ncrease f the resdual energy of the node s too low. So, nodes wth too low resdual energy wll be dffcult to be chosen as the next hop n the route dscovery, whch s helpful to balance the energy expendture. 4 Smulaton and Analyss We nvestgated the AELAR s performance by comparng t wth tradtonal GPSR and energy-aware GEAR. We also optmzed our algorthm (AELAR-O wth the method n [1] to confrm that the paths dscovered by AELAR are almost as short as possble. Fg.(a shows that number of packets delvered by AELAR s more than GPSR and GEAR durng the network lfetme. From Fg.(b and Fg.(c, we can learn that AELAR successfully acheves energy effcency and has lower energy devaton because the nodes energy dfferences s exaggerated by logarthmc functon. Fruthermore, owng to the use of the adaptve mechansm, we learn that AELAR almost has the same average path hop as GPSR from Fg.(d, whch s benefcal to the data delay reducton whle consderng energy conservaton.

5 5 Conclusons Ths paper has proposed a new routng algorthm, AELAR, whch s locaton-based, energy-aware, and scalable to dscover the paths between the source node and the snk. We frst present a novel method of dvdng routng request zone and then construct a select equaton for a node to choose ts next hop. Both the routng request zone and the select equaton can be adusted by the node accordng to ts own locaton. Ths adaptve mechansm makes sure that the paths found by AELAR are as short as possble whle consderng the energy conservaton. The smulaton results show that AELAR performs better n terms of network lfetme, energy utlzaton, energy consumpton balancng and data delay reducton than tradtonal routng algorthms. References 1. Ycka, J., Mukhereea, B., Ghosal, D.: Wreless sensor network survey. In: Computer Networks, Vol. 5, no. 1, pp , August Woo, K., Yu, C., Lee, D., Youn, H.Y., B, L.: Non-blockng, localzed routng algorthm for balanced energy consumpton n moble ad hoc networks. In: Proceedngs of Nnth Internatonal Symposum on Modelng, Analyss and Smulaton of Computer and Telecommuncaton Systems, Cncnnat, OH, USA, 001, pp Ko, Y.B., Vadya, N.H.: Locaton-aded routng n moble ad hoc networks. In: Wreless Networks, vol. 6, no. 4, pp , Shh, T.F., Yen, H.C.: Locaton-aware routng protocol wth dynamc adaptaton of request zone for moble ad hoc networks. In: Wreless Networks, vol. 14, no. 3, pp June Chen, M., Leung, V.C.M., Mao, S., Xao, Y., Chlamtac, I.: Hybrd geographc routng for flexble energy-delay tradeoff. In: IEEE Transactons on Vehcular Technology, vol. 58, no. 9, pp , November Kranaks, 1.E., Sngh, H., Urruta, J.: Compass routng on geometrc networks. In: Proceedngs 11th CCCG Vancouver, BC, Canada, August 1999, pp Karp, B., Kung, H.T.: GPSR: greedy permeter stateless routng for wreless networks. In: Proceedngs of ACM Annual Conference on Moble Computng and Networkng, Boston, MA, USA, August 000, pp Yu, Y., Govndan, R., Estrn, D.: Geographcal and energy aware routng: a recursve data dssemnaton protocol for wreless sensor networks. In: UCLA Computer Scence Department Techncal Report, 001, pp L, Y., A, C., Ca, Z., Raheem, B.: Sensor Schedulng for p-percent Coverage n Wreless Sensor Networks. In: Journal of Cluster Computng, Sprnger Netherlands, May W. Keb, H. Fubler, J. Wdmer, Herarchcal locaton servce for moble ad hoc networks, Moble Computng and Communcatons Revew, vol. 8, no. 4, pp , Chen, M. L., Vctor, C. M., Mao, S., Yuan, Y.: Drectonal geographcal routng for realtme vdeo communcatons n wreless sensor networks. In: Computer Communcatons. Concurrent Multpath Transport, vol. 30, no. 17, pp , Shu, L., Zhang, Y., Yang, L.T., Wang, Y., Hauswrth, M.: Geographc routng n wreless multmeda sensor networks. In: Proceedngs of the nd Internatonal Conference on Future Generaton Communcaton and Networkng (FGCN 008, Hanan, Chna, December 008.