Analysis on DV-Hop Algorithm and its variants by considering threshold

Transcription

1 Analysis on DV-Hop Algorith and its variants by considering threshold Aanpreet Kaur 1, Pada Kuar 1, Govind P Gupta 2 1 Departent of Coputer Science & Engineering Jaypee Institute of Inforation Technology, Noida, India 2 Departent of Inforation Technology National Institute of Technology, Raipur, India aanpreet.kaur1410@gail.co Abstract Wireless Sensor networks is a network of lowpriced, sall sized and energy constraint sensor nodes where each sensor node is prograed to sense the events and send it to the Base station using ulti-hop counication. In alost all applications of Wireless Sensor Networks, event detection inforation is required along with the location of the event. Thus, to find the location of event, node localization plays an iportant role. Many researchers have put treendous efforts in designing localization algoriths. In the literature, it is confired that DV-Hop algorith and its variants are the ost suitable range-free based algoriths for node localization, due to its cost effectiveness, siplicity and feasibility for ediu to large scale networks, but these algoriths consue very high energy. The DV-Hop algorith works in three phases. The first phase allows all the nodes to get their distance fro few localized nodes called anchors in ters of hop. The hop is the count of neighboring nodes between two nodes. Then in second phase, the anchor nodes find out their approxiate distances fro every node. The third phase coputes the location of node using the inforation obtained fro first two phases and by applying trilateration ethod. The high energy is consued due to transission of large nuber of packets in the first two phases by anchor nodes. In order to reduce counication overhead of the first two phase of DV-Hop, an iproved DV-Hop is proposed that considers only k-hop transission of the anchor packet which reduces the counication overheads to the large extent. Siulation experients and results prove that the proposed ethod reduces the energy consuption by approxiately 50% copare to the traditional DV-Hop algorith. Index Ters DV-Hop; Localization; Threshold; Wireless Sensor Networks. I. INTRODUCTION A typical Wireless sensor network (WSN) contains a collection of low-priced, sall, and energy constraint sensor nodes which are used to detect soe events in the target area of the interest [1]. These sensor nodes identify event and pass this inforation to the base station by eans of their neighboring nodes [1]. WSNs are broadly utilized for different applications, for exaple, ilitary and national security application, environental observing, health application, air control, pollution control, fire location, etc[1-2]. In ost application of WSNs, any event data without its location is good for nothing. For instance, in ilitary application, both event (intruder) and place (location) where intruder is recognized are required. In this anner, Localization is a critical requireent in alost all application of WSNs. In literature, nuerous algoriths have been proposed in recent decade. According to cost, the localization algoriths have been arranged into two classes: Range-based and Range- free ethods [3]. Range-based localization ethods require costly equipent to localize the sensor node with high exactness. Soe of Range-based ethods are: received signal strength indicator (RSSI) [4], tie of arrival (TOA) [5], tie difference of arrival (TDOA) [6], and angle of arrival (AOA)[7], and so on. On the other hand, Range-free ethods apply estiation techniques to decide node s location and do not require any costly equipent. They utilize few anchor nodes that have knowledge about their position. There are any Range-free ethods, for exaple, Centroid [8], DV-Hop [9], Aorphous [10], MDS [11] and APIT [12]. Although Range-based algoriths give precise results, Range-free based ethod is favored because of their ease and less cost. In this paper, we concentrate on Range-free DV-Hop algorith and its variants that are popular because of its siplicity, feasibility for sall to large scale WSNs and useful for those nodes that are having less than three neighbors [13]. But, DV-Hop has a few drawbacks, for exaple, low localization precision, high power utilization and high counication overhead. In this paper, we have focused in reducing the counication overheads of the first two-phase of the traditional DV-Hop [9] algorith and its variants by proposing an iproveent to restrict the transission of packets by using threshold paraeter. Siulation experients deonstrate that the proposed ethod reduces energy consuption approxiately 50% when copared with traditional DV-Hop [9] algorith. This paper akes following two contributions to the localization issue in WSNs: i) An iproved DV-Hop is proposed that considers only k-hop transission of the anchor packet which reduces the counication overheads to the large extent.. ii) Perforance analysis and its coparison with the traditional DV-Hop [9] and Weighted-DV-Hop [14] algorith in ters of energy consuption are discussed in detail. The reaining part of the paper is coposed as follows. Section 2 gives the survey of related work. In Section 3, the proposed ethod is clarified. Section 4 shows the siulation results and ain findings of the paper. At last, we put the concluding rearks in Section 5. ISSN: e-issn: Vol. 9 No. 4 79

2 Journal of Telecounication, Electronic and Coputer Engineering II. RELATED WORK A. DV-Hop algorith The DV-Hop was proposed by D. Niculesco et al. [9]. It can be described using three steps as described below. i. Getting the sallest nuber of hops In this phase, each anchor node broadcast an anchor essage in the network. The organization of the anchor essage is {id, xi, yi, hops i}. The hops i is used to find the shortest path between anchor and the node by counting least nuber of hops between these two. The beginning value of hops i is 0 at the anchor. Each receiving node aintains an anchor data table and keeps the sallest nuber of hops fro different anchor nodes in the table. After a tie frae, all nodes in the syste will have the sallest nuber of hops fro every anchor node. ii. Estiation of the distance aongst Anchors and nonanchor nodes In this phase, the anchor nodes get distance of different anchor nodes in ters of hop count using Step 1 of DV- Hop. After the first step, anchor node i finds average distance per hop (AvgHopDistance i ) by using sallest hops and distance between anchors. Forula for calculating the AvgHopDistance i is described as follows: AvgHopDistance i = i=1 i#j (x j x i ) 2 + (y j y i ) 2 i=1 i#j hops i Where is quantity of anchor nodes, hops i is the sallest nuber of hops between anchor nodes i and j, (x i,y i) and (x j,y j) are the locations of anchors i and j, respectively. Each anchor counicates its AverageHopSize to the entire syste. Each non-anchor node gets all anchors AvgHopDistances and chooses the AvgHopDistance j of a nearest anchor as its AverageHopDistance j. In the end, it calculates the distance (d i) fro each anchor i by using Eq. (2) as follows: (1) d i = AvgHopDistance j hops i (2) iii. Estiation of location. In the final step, the non-anchor nodes can estiate their positions by applying either trilateration [9] or ultilateration echanis [9]. B. Iproved Variants of DV-Hop Nuerous researchers have proposed nuerous iproveents to iprove perforance of the DV-Hop algorith. In this section, we have discussed soe iproved variants of DV-Hop algorith. In [14], the weighted centroid based algorith (Weighted DV-Hop) was proposed to reduce coputational coplexity and consued energy of DV-Hop. It used the weight factor that was inversely proportional to sallest nuber of hops to find the location (x nb,y nb) of the non-anchor by applying equation (3). where w i = x nb = 1 hops i i=1 w ix i i=1 w i, y nb = i=1 w iy i i=1 w i (3), is the weight of each anchor i. The weight factor gives higher priority to nearest anchor. This algorith has low coputational coplexity as it skips one step involving coputing average distance per hop by anchors and broadcasting it to other nodes. Also, it consues less energy due to broadcasting of fewer packets (required only for first step). Another iproved weighted centroid algorith (IWCA) was proposed in [14] which consist of three steps. The refineent is done in the second step by taking average of average-hop-distances (say, HopSize). In the third step, the weight factor is deterined by applying Equation (4). w i = ( 1 r HopSize ) hops i Where r is the transission radius of the sensor node. This algorith achieves higher localization accuracy, but consues ore energy due to broadcasting of ore nuber of packets. In [15], G.Song et al. designed an iproved weighted centroid DV-Hop (IDWCA). This algorith uses Equation (5) to get weight value by non-anchor sensor node. w i = i=1 hops i (4) hops i (5) In [16], the algorith adds a fourth step (correction step) to enhance its localization precision. In [16], one ore algorith was introduced that picks only three best anchors to locate a sensor node in the last step of the DV-Hop algorith. In [17], the algorith adds a inor change by taking the difference of average hop distance and transission radius, while coputing distance between nodes to get ore accuracy. In [18], the algorith adds a coefficient in the distance between various nodes to reduce error. In [19], genetic algorith was used with DV-Hop for better accuracy. G.Song et al. [14] designed one ore algorith that substitutes hyperbolic ethod in the last step of DV-Hop to achieve better results in ters of accuracy. In [20], three algoriths were introduced. The first two algoriths added one ore step that uses trigonoetry to achieve higher accuracy. The third algorith replaces the linear proble into non-linear proble in the last step and then solves it by applying quadratic prograing ethod. In all above algoriths, the first two steps are sae and consues large aount of energy due to broadcasting. If soehow, this transission is controlled, then energy consuption can be significantly reduced. Despite the fact that all the related work entioned above iproves the localization accuracy, but very few works have concentrated on reducing consued energy. In this paper, we have proposed an iproved DV-Hop algorith which reduces the energy consuption of the network. III. PROPOSED METHOD In this section, we present an iproveent in the first two steps of the DV-Hop algorith, by restricting the broadcasting of the anchor essage to few hops. The assuption used is that the anchor nodes are distributed uniforly in the WSN area and their percentage is at least 10% of total nodes in the WSN. A detail discussion of iproved DV-Hop is given beneath: 80 ISSN: e-issn: Vol. 9 No. 4

3 Analysis on DV-Hop Algorith and its variants by considering threshold A. Iproved DV-Hop Algorith The proposed iproveent in the DV-Hop algorith works as follows: Step 1: In the first step, anchor packet is only forwarded to a specified nuber of hops fro each anchor node. This specified nuber of hops is called threshold value which is defined as k- hops. By liiting the broadcasting of the anchor packet to a threshold value (i.e. k- hops), we can lessen the energy consuption of the network which relies on the nuber of packets transitted in the network. The working of the first step is as follows: At first, each anchor node i counicates its position (x i,y i) to all non-anchor nodes in the for of packet that are forwarded to a fixed nuber of hops i.e. k.. The packet constitutes <x i, y i, hops i> inforation. The hops i is initialized to 0. Each sensor nodes saves inforation about all the anchor nodes that lies in a threshold region in its hop table containing <i, x i, y i, hops i> for each anchor i. When the packet is received by a particular node, the node verifies it with its hop table, and if the received hops i value is less than stored hops i value in the table and the hops i is less than k, then it saves the new hops i value in the table, and forwards the packet with increented hops i value to other nodes, otherwise it discards the received packet. In this anner, after the first step, all sensor nodes get sallest nuber of hops fro all anchors that lie in their threshold region. Step 2: This step is like the second step in the traditional DV-Hop [9] algorith with the difference that broadcasting is done within threshold region. Here, each anchor node i coputes average distance per hop (AvgHopDistance i) utilizing Equation (1). The value of in Equation (1) is nuber of anchor nodes that are within a threshold region. After this, each anchor node i counicate it to different sensor nodes that are within a threshold range (i.e. k-hop). By considering this iproveent, the energy consuption is further reduced. The non-anchor nodes estiate their distance fro anchor nodes by applying Equation (2). The sensor nodes now have distances fro only those anchor nodes that are within threshold range. By restricting broadcasting to the threshold (only within k hops) range, the anchor nodes transit now fewer packets and thus reduce energy consuption. Step 3: The third step is siilar to the third step of the traditional DV-Hop [9] algorith. Siilarly, other variants of DV-Hop Algoriths can be iproved by refining their first two steps. IV. SIMULATION RESULTS AND FINDINGS To prove the effectiveness of the iproved DV-Hop and its variants, the algorith is siulated in Matlab2013. In this section, we presented the results in ters of consued energy. The consued energy depends upon the nuber of packets transferred between nodes in the network. It ay be expressed as: Consued Energy = 2 (n 1) En (6) Where n is total nuber of nodes, is the total nuber of anchors, En is the average energy used to transit a packet. The siulation experient copares the proposed iproved algorith with other two algoriths (DV-Hop [9] and Weighted DV-Hop [14]) on the basis of consued energy by changing total nuber of anchors. 500 nodes are deployed in a WSN network and the counication radius is assigned to 100. The count of anchors is increased fro 50 to 200 to see the effect on consued energy for different values of threshold (i.e. k) value. Perforance coparison between algoriths for different values of threshold (i.e. k) value is shown in Figure 1 to Figure4. The siulation paraeters used for the experient are displayed in Table 1. Siulation Paraeters Table 1 Siulation paraeters Value WSN Area Total Nodes 500 Anchor Nodes Vary fro 50 to 200 Total iterations 50 threshold value(k) Vary fro 2 to 5 Counication radius 100 Figure 1: Coparison by varying threshold value (total anchors=50) Figure 1 shows the perforance analysis of the proposed iproved DV-Hop with the traditional DV-Hop [9] and Weighted DV-Hop [14] algorith in ters of energy consuption by varying the threshold value k fro 2 to 5. In this experient, total 500 nodes are deployed and 50 of the are anchor nodes. It is observed fro the figure 1 that proposed iproved DV-Hop algorith takes less energy copare to the other two algoriths, traditional DV-Hop [9] and Weighted DV-Hop[14]. This is due to fact that proposed ethod transits less counication overheads copare to the other ethods. During experients, it is observed that for k=2, traditional DV-Hop [9] and weighted DV-Hop [14] transits 50,000 and packets, respectively, whereas our proposed ethod broadcasts packets. As the value of k increases, the proposed ethod starts consuing ore energy and is equal to Weighted DV-Hop[14] for k=5. Figure 2 shows the result for the WSN network with 100 anchor nodes. It is shown that the proposed algoriths consue packets fro to for different values of k. The proposed algorith consues alost 70% less energy for k=2 when copared with DV-Hop and 20% less energy when copared with Weighted DV-Hop. ISSN: e-issn: Vol. 9 No. 4 81

4 Journal of Telecounication, Electronic and Coputer Engineering nuber of nodes and a fixed nuber of anchors. The Weighted DV-Hop skips packet transission in its second phase, so it consues energy equal to half as that traditional DV-Hop [9]. In the proposed algorith, the consued energy increases with the increase in threshold (k) value. Thus we should take the iniu value of k is 2 as an optiu threshold value to iniize energy consuption. It is also observed that with the increase in threshold value, the energy consuption increases. V. CONCLUSION Figure 2: Coparison by varying threshold value (total anchors=100) For the results as shown in Figures 3 and 4, the anchor nodes are raised to 150 and 200 respectively. The perforance of the proposed algorith is best for k=2 in ters of energy consuption. In Figure 3, the proposed algorith iproves by 66% in ters of energy reduction when copared with DV-Hop[9] and by 33% when copared with Weighted DV-hop[14 when k is equal to 2. Figure 4 shows that the proposed algorith reduces energy by 75% when copared with DV-Hop[9] and by 33% when copared with Weighted DV-Hop[14] algorith when k is equal to 2. Figure 3: Coparison by varying threshold value (total anchors=150) Figure 4: Coparison by varying threshold value (total anchors=200) Fro the result as shown in fro Figure 1 to Figure 4, it is proved that proposed algorith perfors better in ters of energy consuption. It is also observed that the consued energy in traditional DV-Hop [9] and Weighted DV-Hop [14] algoriths depends upon the total nubers of nodes and anchor percentage. Thus the consued energy is constant for both algoriths in each experient for fixed This paper gives the suary of issues of DV-Hop algorith and its variants. The priary issues are low accuracy and high energy consuption. In order to reduce energy consuption, we have proposed an iproved DV- Hop algorith which reduces the power consuption by liiting the transission of the anchor packet to the axiu k-hop. Through siulation results, it is deonstrated that the iproved algorith perfors superior to other algoriths in ters of consued energy. In the future, we will plan to expand this work for 3D WSNs. REFERENCES [1] Nayak and I. Stojenovic, Applications, Models, probles, and Solution Strategies, in Wireless Sensor and Actuator Network, Ed. New Jersey: Wiley, ch. 1, pp. 3-4, [2] J. Zhao, W. Xi, Y. He, Y. Liu, X.-Y. Li, L. Mo, and Z. Yang, Localization of Wireless Sensor Networks in the Wild: Pursuit of Ranging Quality,IEEE/ACM Transactions on Networking, vol 21, no.1,pp ,Feb [3] H.Chen, K.Sezaki, P.Deng and H.C.So, "An iproved DV-hop localization algorith for wireless sensor networks," In Proceedings of IEEE Conference on Industrial Electronics and Applications, Singapore, pp , [4] L. Girod, V. Bychobvskiy, J.Elson and D. Estrin,.Locating tiny sensors in tie and space: a case study., In Proceedings of the 2002 IEEE International Conference on Coputer Design: VLSI in Coputers and Processors, Los Alaitos, pp ,2002 [5] A. Harter, A. Hopper, P. Steggles. A. Ward and P. Webster, The anatoy of a context-aware application, Wireless Networks, Vol 8, no.2, pp ,2002 [6] X. Cheng, A.Thaeler, G. Xue, and D. Chen, TPS: a tie-based positioning schee for outdoor wireless sensor networks, in Proceedings of the 23rd IEEE Annual Joint Conference of the IEEE Coputer and Counications Societies (INFOCOM 04), pp , Hong Kong, China, March [7] D. Niculescu, and B. Nath, Ad hoc positioning syste (APS) using AoA, In Twenty-Second Annual Joint Conference of the IEEE Coputer and Counications. IEEE Societies, Vol. 3, pp ,2003. [8] N. Bulusu, J. Heideann, D. Estrin, GPS-less low cost outdoor localization for very sall devices, IEEE Personal Counications Magazine, Vol 7, no. 5, pp ,2000. [9] D. Niculescu and B. Nath, Ad-hoc positioning syste., In IEEE on Global Telecounications Conference,Vol 5, pp , [10] R. Nagpal, Organizing a global coordinate syste fro local inforation on an aorphous coputer", A.I. Meo1666, MIT A.I. Laboratory,1999. [11] Y. Shang andw. Rul, Iproved MDS-based localization, in Proceedings of the IEEE Conference on Coputer Counications (INFOCOM 04), pp ,HongKong, March [12] T. He, C. D. Huang, B.M. Blu, J.A. Stankovic, and T. Abdelzaher, Range-free localization schees for large scale sensor netowrks, in Proceedings of the 9th the Annual International Conference on Mobile Coputing and Networking, pp , ACM, San Diego, Calif, USA, [13] L.Gui, T. Val, A. Wei, R. Dalce, Iproveent of range-free localization technology by a novel DV-hop protocol in wireless sensor networks,ad Hoc Networks, [14] B. Zhang, M. Ji, and L. Shan, A weighted centroid localization algorith based on DV-hop for wireless sensor network, in 82 ISSN: e-issn: Vol. 9 No. 4

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