SCALABLE ENERGY EFFICIENT AD-HOC ON DEMAND DISTANCE VECTOR (SEE-AODV) ROUTING PROTOCOL IN WIRELESS MESH NETWORKS

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1 SCALABL NRGY FFICINT AD-HOC ON DMAND DISTANC VCTOR (S-AODV) ROUTING PROTOCOL IN WIRLSS MSH NTWORKS Sikande Singh Reseach Schola, Depatment of Compute Science & ngineeing, Punjab ngineeing College (PC), Deemed Univesity, Secto-2, Chandigah-6002 (India) D. Tilok Chand Asei S. Lectue, Depatment of Compute Science & ngineeing, Punjab ngineeing College (PC), Deemed Univesity, Secto-2, Chandigah-6002 (India) ABSTRACT A new outing potocol called Scalable negy fficient Ad-hoc on Demand Distance Vecto (S-AODV) having good scalable popeties and enegy efficient than existing Ad hoc on Demand Distance (AODV) outing potocol in wieless mesh netwoks has been poposed in this pape. Wieless mesh netwoks (WMNs) consist of mesh outes and mesh clients, whee mesh outes have minimal mobility and fom the backbone of WMNs. They povide netwok access fo both mesh and conventional clients. Two techniques called Clusteing and Blocking-xpanding Ring Seach has been applied on existing AODV outing potocol to impove its scalability and enegy efficiency poblem. Results shows that, pefomance of S- AODV outing potocol is bette than existing AODV outing potocol in wieless mesh netwoks. To show the efficiency of ou poposed outing potocol, simulations have been done by using Netwok Simulato-2 (NS-2). Keywods: Wieless mesh netwoks, Ad-hoc netwok, Routing, Distance vecto. INTRODUCTION Wieless mesh netwok (WMN) [] technologies have been actively eseached and developed as key solutions to impove the pefomance and sevices of wieless pesonal aea netwoks (WPANs), wieless local aea netwoks (WLANs) and wieless metopolitan aea netwoks (WMANs) fo a vaiety of applications, such as voice, data and video. Compaed with mobile ad hoc netwoks (MANTs), wieless senso netwoks (WSNs) and infastuctuebased mobile cellula netwoks, WMNs ae (i) quasistatic in netwok topology and achitectue (ii) not esouce constained at mesh outes and (iii) easy and flexible to deploy. These technological advantages ae especially appealing to the emeging maket equiements on futue wieless netwoks and sevices, such as flexible netwok achitectue, easy deployment and self-configuation, low installation and maintenance costs and inteopeable with the existing WPAN, WLAN and WMAN netwoks. Potential applications of WMNs include boadband home netwoking, community and neighbohood netwoking, entepise netwoking, building automation and so on. These wide anges of applications have diffeent technical equiements and challenges in the design and deployment of mesh netwoking achitectues, algoithms and potocols. The objective of this wok is to develop outing potocols fo Wieless Mesh Netwoks and to analyze thei pefomance by ealizing diffeent envionments. The analysis has been done theoetically and though simulations using NS-2 (Netwok Simulato-2). Objectives of the wok ae:-. To simulate the poposed outing potocol, Scalable negy fficient-ad-hoc on-demand Distance Vecto (S-AODV) fo wieless mesh netwoks. 2. valuation of outing potocols based on vaious paametes. 3. Compaison of poposed potocol with existing potocol. 2 RLATD WORK Wieless mesh netwoks has ecently gained a lot of populaity due to thei apid deployment and instant communication capabilities. These netwoks compise of somewhat static multi-adio Mesh Routes [2], which essentially povide connectivity Ubiquitous Computing and Communication Jounal

2 between the mobile single-adio Mesh Clients. Special outing potocols ae employed which facilitate outing between the Mesh Routes as well as between the Mesh Routes and the Mobile Clients. AODV is a well known outing potocol that can discove outes on-the-fly in a mobile envionment. Howeve, as the potocol was actually developed fo single-adio nodes, it fequently lacks the ability to exploit the potential offeed by the Mesh Routes. Thee ae hundeds of poposed outing potocols [3], many of them have been standadized by ITF and have been in use fo many yeas. Some of those potocols have poven themselves in the Intenet and ae expected to continue to pefom well fo many yeas to come. In the ad-hoc netwoking aena, seveal classes of outing potocols have been poposed and caefully analyzed. The WMN companies [4] ae using a vaiety of outing potocols to satisfy thei needs. Futhemoe poposed outing potocol takes advantage of the fixed nodes in WMNs. In this pape some enhancements ae done to impove the existing AODV potocol so that it woks well in wieless mesh netwoks having good scalability and enegy efficient. 3 SCALABL NRGY FFICINT AD- HOC ON DMAND DISTANC VCTOR ROUTING PROTOCOL (S-AODV) In this pape to develop S-AODV Routing Potocol two techniques called Clusteing and Blocking xpanding Ring Seach have been applied to impove the pefomance of existing AODV outing potocol in wieless mesh netwoks. The pefomance of wieless mesh netwoks is highly dependent on outing potocol. AODV is a popula outing potocol fo wieless netwoks. AODV is well suited fo wieless mesh netwoks in that it has low pocessing & memoy ovehead and low netwok utilization. Additionally AODV povides loop feedom fo all outes though the use of sequence numbes. 3. Design Goals The design goal of S-AODV outing potocol is to impove the scaling potential of AODV and to make it enegy efficient. The main featue of AODV- Clusteing includes:- (i) Gadualness The potocol fist woks on AODV method, then gadually changes to a clusteing oute potocol. Thee ae seveal consideations about it: Fist, thee is cental contol node in mesh netwok; second, using this method can also allow AODV nodes coexisting with AODV-Clusteing nodes; thid, it can educe the ovehead caused by fequently changing of cluste. (ii) Coexist with AODV AODV is a widely accepted outing potocol. Thee ae seveal implemented vesion of AODV epoted. One of the impotant pinciples in designing AODV-Clusteing is the coexistence with AODV; it means nodes which implement AODV potocol can wok collaboatively with nodes that implement poposed potocol in the same netwok. To achieve this, keep all AODV oute contol packets and add some new contol packets as needed. In fact AODV-Clusteing let all nodes that haven t joined a cluste woks on AODV method. (iii) Route Discovey Mechanism In AODV-Clusteing, thee ae two oute discovey mechanisms fo the nodes which join the cluste. One is Blocking-RS, it can incease the efficiency of the oute discovey; the othe is taditional RRQ flooding oute discovey mechanism which extends fom AODV. Nomally Blocking-RS is used fist, if a suitable oute can t be found befoe timeout, then taditional oute discovey mechanism is used. (iv) Local Route Repai To educe the numbe of lost data packets, when the oute boke due to mobility, AODV-Clusteing let the node upsteam of the beak link pefom a local epai instead of issuing the RRR. If the local epai is successful, a RRP will be etuned eithe by the destination o by a node with a valid oute to the destination. In the event that a RRP is not etuned, the local epai is not successful and a RRR message is sent to the souce node. 3.2 AODV-Clusteing Routing Scheme (i) Route Discovey At the beginning the status of all nodes is unassigned. Souce node boadcast [5] RRQ message to find a oute, destination node o intemediate node that has fesh oute to destination eply with RRP message to souce. On the way which RRP pass by, one o seveal nodes ae selected as cluste head (CH) using a defined ule. CH node will boadcast CH message to its neighbous, the neighbou nodes which eceive this boadcast will act diffeently accoding to its oles. (a) Fo node whose status is unassigned, it will issue a Join Cluste Request to the boadcasting CH and can become an odinay cluste membe afte eceiving the acknowledgment fom this CH. In AODV-Clusteing, CH node can each all his membes by one hop, so the potocol s achitectue is one level hieachy. (b) Fo node which is an odinay cluste membe, it will judge if the boadcast message sende is its oiginal CH, if yes, no action needed; else, send Join Cluste Request to the CH and become gateway node afte eceiving acknowledgement fom it. Being a gateway, it will send Gateway Message to all CH nodes which it connect diectly, let them put its addess in thei Gateway Table. Ubiquitous Computing and Communication Jounal 2

3 (c) Fo node which is a gateway, it will check its Gateway Node Table whethe thee is an enty fo this boadcasting CH node, if yes, no action needed; else, send Join Cluste Request to it and put its addess into Gateway Node Table afte eceiving acknowledgement fom it. Gateway nodes have two tables, one is Gateway Node Table which contains cluste head addess which it connect diectly, anothe is Joint Gateway Table, which contains addess of the CH nodes which can be eached by 2 hops and also the nodes which help to each these CHs which ae called Joint Gateway. (ii) Route Maintenance AODV-Clusteing extends many featues fom AODV fo oute maintenance, fo example, use hello message to confim the existence of neighbous, use RRR message to infom the nodes affected by the link beakage. In addition to it, AODV-Clusteing adds some cluste elated maintenance opeations such as joining cluste, leaving cluste and changing its status. (a) Joining Cluste The nodes whose status is unassigned will join the cluste afte eceiving the CH Boadcasting Message. To educe ovehead, no peiodic CH Boadcasting is used. Instead, a on demand method is used fo new nodes to join cluste: when the node whose status is unassigned boadcast RRQ to its neighbous, a specific mak is set in RRQ, the mak will infom neighbouing CHs to let him join the cluste. Using this way, unassigned node that newly comes will have a chance to join the neaby cluste when it has data to send. (b) Leaving Cluste If the odinay cluste membe finds its CH node uneachable, it will change its status to unassigned. This means the node leaving the cluste. CH node should change its status to unassigned when it has no cluste membes. (c) Changing Cluste In AODV-Clusteing, the change of cluste is not occued immediately. When the node leave the cluste, its status become unassigned, it woks on AODV method until new CH node appea neaby and it has a chance to join the cluste. 3.3 Route Discovey Appoaches in Wieless Mesh Netwoks In Wieless mesh netwoks, nodes coopeating fo delivey of a successful packet fom a communication channel consisting of a souce, a destination and possibly a numbe of intemediate nodes with fixed base station. In this pape some inefficient elements have been found in well known eactive potocols AODV and popose a new appoach fo eboadcasting in xpanding Ring Seach. This leads to the Blocking-RS scheme, as we call it, which demonstates impovement in enegy efficiency at the expense of oute discovey time in compaison to conventional oute seach method Blocking-RS An altenative RS scheme has been poposed to suppot eactive potocols such as DSR (Distance Souce Routing) and AODV and it is called Blocking xpanding Ring Seach. The Blocking-RS integates, instead of TTL sequences, a newly adopted contol packet, stop instuction and a hop numbe (H) to educe the enegy consumption duing oute discovey stage. The basic oute discovey stuctue of Blocking-RS is simila to that of conventional TTL sequence-based RS. One of the diffeences fom TTL sequence-based RS is that the Blocking-RS does not esume its oute seach pocedue fom the souce node evey time when a eboadcast is equied. The eboadcast can be initialized by any appopiate intemediate nodes. An intemediate node that pefoms a eboadcast on behalf of the souce node acts as a elay o an agent node. Fig. shows an example of Blocking RS appoach in which the eboadcasts ae initialized by and begins fom a elay node M in eboadcast ound 2 and anothe elay node N in ound 3 and so on. In Fig. the souce node boadcasts a RRQ including a hop numbe (H) with an initial value of. Suppose that a neighbou M eceives the RRQ with H= and the fist ing was made. If no oute node is found, that is, no node has the equested oute infomation to the destination node, the nodes in the fist ing eboadcast the RRQ with an inceased hop numbe, fo example RRQ with H=2 is eboadcast in this case The ing is expanded once again just like the nomal expanding ing seach in AODV except with an extended waiting time. The waiting time can be defined as Waiting Time = 2 Hop Numbe The nodes in Blocking-RS eceiving RRQs need to wait fo a peiod of 2H, i.e. 2 thei hopnumbe unit time befoe they decide to eboadcast, whee the unit time is the amount of time taken fo a packet to be deliveed fom one node to one-hop neighbouing node. Figue : Blocking-RS (A) negy Consumption Ubiquitous Computing and Communication Jounal 3

4 negy consumption duing the tansmission of RRQs can be saved by using the Blocking-RS scheme. Let the amount of enegy consumption on each node fo one boadcast is the same unit enegy consumption, denoted by Unitnegy. Assume that each action of boadcasting a RRP, RRQ o stop instuction consumes the same amount of Unitnegy. This can be easily shown by the diffeence of the enegy consumption between the conventional TTL sequence-based RS and the Blocking-RS scheme. (i) One oute case: - Fist conside only the enegy consumption along the oute fom the souce to the oute node. The enegy consumption fo the TTL based RS and fo the Blocking-RS can be descibed by the following fomula (q. () and q. (2)) espectively, whee H is the hop numbe of the oute node. H TTL RS + = H i( Unitnegy) () Blocking RS = 3H ( Unitnegy) (2) The diffeence of the amount of enegy consumption is moe visible fom Fig. 2 whee the amounts of enegy consumption by the two RS appoaches ae plotted against the numbe of ings. The Blocking-RS cuve is below the TTL based RS cuve afte ing 3. As it is clea fom Fig. 2, the diffeence of the amount of enegy consumption between these two mechanisms becomes lage as the distance inceases between the souce and the oute node. sending the stop instuction. Fo the conventional TTL based RS, the enegy consumption duing the oute discovey pocess includes that in two stages: (a) seaching fo the oute node and (b) etun RRP. The enegy consumed fo (b) etuning a RRP is H Unitnegy fo both outing schemes and H Unitnegy is consumed fo the Blocking-RS stage (c) sending the stop instuction. In the stage of (a) seaching fo the oute node, the enegy consumption is diffeent fo the two methods. ach ing contains diffeent numbe of nodes that eboadcast to fom the next ing. Let n i be the numbe of nodes in ing i and the hop numbe of the oute node be H. In the Blocking-RS, the enegy consumed in each ing is as below: - Ring i negy Consumed 0 n H - n h- In the TTL based RS, the enegy consumed in each ing is as follows: - Ring i negy Consumed 0 + n H - + n + n n h- Theefoe, the total enegy consumption by the Blocking- RS is given by q. (3) Blocking RS H = 2( + ni ) + RRP ( Unitnegy) (3) Similaly, the total enegy consumption by the conventional TTL sequence based RS is given by q. (4) TTL RS H = H + n i i j= j + RRP ( Unitnegy ) (4) The diffeence between the TTl RS is given by q. (5) Blocking RS and Saved H = H 2 + (( n i j= j ) 2 ni )( Unitnegy) (5) Figue 2: Compaison of enegy consumption fo one oute (negy is measued in Joule, and Distance in numbe of hops) (ii) Geneal case: - Now conside the geneal case. Fo the Blocking-RS, the enegy consumption duing the oute discovey pocess can be consideed as the total enegy consumption in thee stages: (a) seaching fo the oute node (b) etun RRP and (c) Clealy, when n i =, fo i =,, H. The above fomulas epesent the enegy consumption fo a single oute. This indicates that the enegy consumption saving achieved by the Blocking-RS fo a single oute is the minimum amount of enegy saving. (B) Time Delay Conside the time delay fo the oute discovey peiod, duing which fom the RRQ is boadcasted fo the fist time, tansmitted fom the souce node to the oute node possibly via flooding. That is the total Ubiquitous Computing and Communication Jounal 4

5 time taken fom when the souce node boadcasts the fist RRQ fo the fist time until afte a Route Node is found and the souce node eceive the RRP fom the Route Node. Let the UnitTime be the one-hop tansmission time, which is the time taken fo a RRQ fom a boadcasting node to one of its neighbou nodes. In case of TTL sequence based RS suppose H = 3, that is the oute node is 3 hops distant fom the souce node. The total time includes the time when TTL =, 2 and 3. The final TTL numbe equals to the hop numbe of the oute node. This gives the following fomula of total time delay fo the TTL sequence-based RS (q. 6): - T TTL RS = H 2 i( UnitTime) (6) Now conside the time delay in the Blocking- RS. The total time includes the time fo thee stages: (a) seaching fo the oute node, (b) etuning the RRP and (c) boadcasting the stop instuction. Fo stage (a), the time consists of the time to fo boadcasting and the waiting time. The boadcasting time fo hop distance is UnitTime. The waiting time depends on the hop numbe of the node. The oute node is 3 hops distant fom the souce node. ach node needs to wait fo 2H befoe eboadcasting. At ing, the node waits fo 2 = 2 UnitTime, and at ing 2, the node waits fo 2 2 = 4 UnitTime, and at ing 3, the node waits fo 2 3 = 6, so the total waiting time fo the (a) stage of seaching fo the oute node is = 2, and the total time fo stage (a) is 2+H = 2+3 = 5. The time fo stage (b) and (c) ae H and this gives 2H = 2 3 = 6. Theefoe, the total time fo the oute discovey and flooding contol is = 2 UnitTime. Mathematical fomula is pesented below, whee H epesents the hop numbe of a oute node. T Blocking RS = 3H + H i( UnitTime) (7) Compae this to the TTL sequence based RS as given in q. (8): - T TTL RS = 2 H (8) It is clea that the diffeence between the two is 3 H thee times of the hop seial numbe of the oute node, depending only on the distance between the souce node to the Route node. The time delay in both appoaches is compaed in Fig. 3 As illustated the Blocking-RS takes slightly moe time than the conventional TTL sequence-based RS fo the oute discovey pocess. 4 PRFORMANC VALUATION 2 i( UnitTime) To evaluate the pefomance of S-AODV outing potocol (AODV-Clusteing with Blocking- RS technique), the simulation is done by using NS- 2 [6]. The pefomance of S-AODV outing potocol is evaluated by compaing it with existing AODV outing potocol in the same conditions. Thee is evaluation of thee pefomance metics: - (i) Packet Delivey Faction: - This is the faction of the data packets geneated by the souces that ae deliveed successfully to the destination. This evaluates the ability of the potocol to discove outes. (ii) Routing Load: - This is a atio of contol packet ovehead to data packet ovehead, measued by the numbe of oute contol packets sent pe data packet. The tansmission at each hop along the oute was counted as one tansmission in the calculation. (iii) Aveage Route Acquisition Latency: - This is the aveage delay between the sending of a oute equest packet by a souce fo discoveing a oute to a destination and the eceipt of the fist coesponding oute eply. If thee is a fesh oute aleady, 0 was used fo calculating the latency. Figue 3: Compaison of the time delay (Time is measued in millisec, and Distance in numbe of hops) The fomula of the time delay in the Blocking- RS is given by q. (7): - Figue 4: AODV, S-AODV packet delivey Ubiquitous Computing and Communication Jounal 5

6 faction As shown in Fig. 4 the packet delivey faction obtained using S-AODV is almost identical to that obtained using AODV when node numbes ae small. Howeve, when thee ae lage numbes of nodes (i.e., moe than 200), S-AODV pefomed bette. This suggests that S-AODV is highly effective in discoveing and maintaining outes fo delivey of data packets. Figue 5: AODV, S-AODV Routing Load Fig. 5 shows the outing load compaison of these two potocols. Routing load is measued by numbes of oute contol packets sent pe data packets. Fo AODV, oute contol packets include RRQ, RRP, RRR and Hello messages, fo S- AODV cluste elated messages such as CH Boadcast Message, Join Cluste Request, Join Cluste ACK, and Gateway message ae also included. It is clea fom Fig. 5, outing load of S- AODV was significantly lowe than AODV when thee ae lage numbes of nodes in netwok. So S-AODV became a hieachical potocol gadually, hieachical outing geatly inceases the scalability of outing in wieless netwoks by inceasing the obustness of outes. pefomed bette than AODV in moe stessful situations (i.e. lage numbe of nodes, moe load), this is geatly contibuted to the Blocking-RS technique of AODV-Clusteing and eduction of the RRQ flooding. 5 CONCLUSION AND FUTUR WORK In this pape Scalable negy fficient AODV (S-AODV) outing potocol has been intoduced to solve the scalability poblem of AODV by applying Clusteing and to make it enegy efficient by using Blocking-RS techniques in wieless mesh netwoks. The pefomance is studied by simulations based on NS-2. The esult shows, that S-AODV potocol achieves bette scalability than existing AODV while keeping the meits of it. The analysis demonstates a substantial impovement in enegy consumption that can be achieved by the Blocking- RS at a magin cost of slightly longe time. Thee ae some limitations still in S-AODouting potocol, such as duing discovey of a oute the technique used in this potocol slightly takes moe time than existing conventional one, so it need futhe study to impove this dawback. 6 RFRNCS [] K. N. Ramachandan: On the Design and Implementation of Infastuctue Mesh Netwoks, I Wksp. Wieless Mesh Netwoks, Calcutta, pp (Sept 2005). [2] R. Daves, J. Padhye, and B. Zill: Routing in Multi-Radio, Multi-Hop Wieless Mesh Netwoks, Mobile Communication, pp (Sept 2004). [3] R. Daves, J. Padhye, and B. Zill: Compaison of outing metics fo static multi-hop wieless netwoks, Poc. of SIGCOMM 04, (Potland, OR), pp (Aug 2004). [4] I. F. Akyildiz and X. Wang: A Suvey on Wieless Mesh Netwoks, I Commun. Mag., vol. 43, no. 9, pp. S23 S30 (Sept 2005). [5] V. Li, H. S. Pak, and H. Oh: A Cluste-Label- Based Mechanism fo Backbone on Mobile Ad Hoc Netwoks, The 4th Wied/Wieless Intenet Communications (WWIC 2006), pp (May 2006). [6] Figue 6: AODV, S-AODV Aveage Route Acquisition Latency Fig. 6 shows the Aveage Route Acquisition Latency of the two potocols. S- AODV Ubiquitous Computing and Communication Jounal 6