A Channel Splitting Technique for Reducing Handoff Delay in Wireless Networks

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1 Interntionl Journl o Engineering Reserch & Technology (IJERT) A Chnnel Splitting Technique or Reducing Hndo ely in Wireless Networks Jeykumr. J #1, Venktesh. * 2, Vigneswri. G* 3, Nivethith. V *4 # 1 PG Scholr (eprtment o ECE), r.mhlingm College o Engineering nd Technology, Pollchi. *2 Asst Proessor (eprtment o ECE), r.mhlingm College o Engineering nd Technology, Pollchi. *3,*4 PG Scholrs (eprtment o ECE), r.mhlingm College o Engineering nd Technology, Pollchi, Indi. Abstrct Hndo mngement plys n importnt role in next genertion wireless network or providing the Qulity o Service to the mobile users. Wireless Mesh Network (WMN) is the most promising nd cost-eicient next genertion wireless network or providing lrge-scle internet bsed wireless ccess. The Intergtewy hndo is mjor concern to gurntee continuous communictions in Internet-bsed Wireless Mesh Networks (WMN). The previous system ocus on intrgtewy hndo designed or single-hop wireless ccess network tht supports only low hndo dely but there is no considertion or reducing the long hndo dely in WMNs due to the existence o multi-hop wireless links. In this pper, we re reducing the long hndo dely ctor by proposing chnnel splitting technique in multihop wireless link. By using chnnel splitting technique, the hndo dely in WMNs is gurnteed nd chnnel utiliztion is improved. The dt tric is reduced nd hence high throughput is chieved. The NS2 simulted results shows tht hndo perormnce cn be improved by our proposed hndo technique. Index Terms Wireless Mesh Network, Intergtewy hndo, Multihop, Chnnel Splitting. I. INTROUCTION The next genertion wireless network hs most promising etures nd wide rnge o unctionlities. The Wireless Mesh Network (WMN) is one o the cost-eicient or providing lrge scle internet ccess. WMN hve the potentil to deliver internet brodbnd ccess, wireless locl re network coverge nd network connectivity or sttionry or mobile host. WMN provides the multi-hop nd multi-pth connection to orm wireless environment o MESH rmework so tht the occurrence o single point cn prevent the ilure[1][2]. In Fig. 1, WMN is composed o combintion o mobile Mesh Clients (MCs) nd sttic Mesh Routers (MRs). Mesh Routers orm wireless multi-hop bckbone network. Mesh Router ccess the network vi Mesh Router which serve s the wireless ccess point(ap). Some Mesh Router ct s gtewy. Mesh Router which re connected to internet entry points to other Mesh Routers vi ingle-hop or multi-hop wireless links. Wireless communiction is without doubt very desirble service s emphsized by the tremendous growth in both cellulr nd wireless locl re networks. primrily, the ones tht re complint with the IEEE mily o stndrds, populrly known s Wi-Fi [1]. Fig. 1 Wireless Mesh Network This pper ocus on hndo design in WMN. There re two types o hndo in WMN 1) Intergtewy hndo 2) Intrgtewy hndo. The Intergtewy hndo occurs when Mesh Client ccess the internet vi dierent gtewy,then the intergtewy hndo process hs two steps i. Link-lyer hndo ii. Network-lyer hndo In the link-lyer hndo process the Mesh client moves to the new subnet ter choosing new Access Point nd then it obtins new IP ddress nd estblish new route to the new gtewy nd ct s Home Agent (HA). Intergtewy hndo hs only Link-Lyer hndo since no IP ddress chnges when Mesh Client moves within subnet. So there is no need o updting the IP in Home Agent. The Link-Lyer hndo in Intrgtewy hndo is sme s Intergtewy hndo. In this pper we ocus on only intergtewy hndo design in WMN. In the Network-lyer hndo, i the signlling pcket is End-To-End (ETE) dely is short enough, then the movement o Mesh Client is trnsprent to pplictions. ue to the dely o chnnel ccess over multi-hop links there exists very long hndo dely in multi-hop WMN nd it degrdes the throughput o the network. In the network-lyer, hndo dely is uelled by the increse in signling pcket ETE dely, which cn ccount or up to 80% o the totl intergtewy hndo dely. Hence, the multihop ETE dely o signling pckets is min component o the long intergtewy hndo dely in 2249

2 Interntionl Journl o Engineering Reserch & Technology (IJERT) Internet-bsed WMNs, prticulrly when the bckbone tric volume is high. this criticl issue is ignored in existing WMN hndo solutions tht mostly ocus on shortening the linklyer chnnel scnning dely [3], optimizing Mobile IP [4] or better network-lyer hndo support [5] nd improving multihop routing in the mesh bckbone [6]. Thereore, this pper ocuses on reducing the long ETE dely o hndo signling pckets in multihop WMNs. Prticulrly, we consider the improvement o the intergtewy hndo perormnce by intelligently splitting chnnel resources to reduce the medium ccess dely nd queuing dely o hndo signling pckets t ech MR. Some pckets, including hndo signlling pckets, my be dropped by MRs due to buer overlow or retry threshold exceed, leding to the ilure o hndos. Thereore, the trnsmission design o hndo signling pckets in the wireless mesh bckbone is crucil to the intergtewy hndo perormnce in WMNs. To overcome this problem we propose chnnel splitting technique to split ech chnnel in the wireless mesh bckbone into two chnnels by mens o the requency division multiple-ccess technique: dt chnnel nd control chnnel. The dt chnnel is used to trnsmit dt pckets, wheres the control chnnel is specilized or delivering hndo signling pckets nd other control pckets. There re lso other chnnel splitting methods proposed previously[7, 8, 9] it hs not been well designed to reduce both the link-lyer nd network-lyer hndo ltencies in Internet-bsed WMNs. In our proposed hndo design, dt pckets nd signlling pckets re delivered in seprte chnnels. They do not interere with ech other; thereby, the hndo ltency cn be mintined within certin level regrdless o the bckground dt tric. II. RELATE WORK to new subnet in the Internet vi new gtewy, networklyer hndo is lso needed to updte the IP ddress nd/or the routing pth between the new gtewy nd the MC. To initite the network-lyer hndo, the MC irst obtins new IP ddress either rom the new AP or the new gtewy. In tht cse the MC obtins new IP ddress rom the new AP bsed on the Mobile IP [10] process. Then, the MC serches n vilble route to the new gtewy nd sends Registrtion Request messge to its HA in the Internet or ddress updte. The HA updtes the new IP ddress o the MC in its dtbse nd sends Registrtion Reply messge to the MC. The whole hndo process is inished when the MC receives dt pckets rom the new AP vi the new gtewy. uring the entire hndo process, severl network-lyer signling pckets, such s Route Request/Response nd Registrtion Request/Reply, re generted to cilitte the continuous communictions o MCs, which my potentilly compete with the dt pckets o other MCs to ccess chnnels in the multihop wireless mesh bckbone. A. Trditionl Hndo Process In the trditionl hndo process when Mesh Client (MC) detects tht the RSS rom the current Access Point (AP) is below certin threshold vlue, then the chnnel scnning process begins or inding the new Access Point. The MC switches its trnsceiver to the irst chnnel nd sends Probe Request messge. Men while, it strts the ProbeTimer. When the Probe Timer expires, the MC proceeds to scn the next chnnel. Hving inished scnning ll the chnnels, the MC processes ll the received Probe Response messges nd determines the AP with the best RSS vlue s its new AP. Then, the MC switches to the new AP s chnnel nd sends n Authentiction Request messge to the new AP, which replies n Authentiction Response messge. Ater being pproved by the new AP, the MC sends Ressocition Request messge to the new AP nd then receives Ressocition Reply messge rom the new AP to complete the link-lyer hndo. I the new AP is connected Fig. 2 Trditionl Hndo Process in WMNs Figure 3 is the trditionl hndo process grph which ws plotted between number o hndo Vs hndo dely in the trditionl network. The grph shows tht the hndo dely is high when the number o hndo is incresed. In the trditionl method only single queue is designed which increses the tric lod nd degrdes the throughput o the network. 2250

3 Interntionl Journl o Engineering Reserch & Technology (IJERT) Number o hndo Fig. 3 Trditionl Hndo Process Grph B. WMN Hndo Mngement Vrious solutions on WMN hndo mngement hve been proposed to optimize the hndo process in order to shorten the hndo ltency [11]. [12] points out tht the chnnel scnning dely ccounts or more thn 90% o the overll link-lyer hndo dely. Hence, dierent link-lyer hndo schemes re proposed on improving the chnnel scnning process to reduce the link-lyer hndo dely [9], [11]. [12] designs lt routing protocol which is triggered by n MN s ressocition to decrese the overll hndo ltency. [13] llows MNs to probe the neighboring APs by ccessing the common control chnnel to shorten both the probe dely nd the uthentiction dely. [14] introduces the concept o temporry IP ddresses to shorten the dely o pplying new Cre-o Address. [3] presents new WMN mobility mngement scheme to reduce the signling cost s well s to shorten the hndo ltency. [4] provides solution to reduce the route discovery dely in the WMN networklyer hndo. [15] uses more thn one AP to hndle the moving clients to relize st hndos in WMNs. To sum up, existing WMN hndo schemes do not consider to resolve the wireless chnnel ccess contentions between hndo signling pckets nd dt pckets during hndo process. Hence, the hndo dely cn be very long during the network-lyer hndo, which genertes hndo signlling tric tht needs to be delivered over the multi-hop wireless mesh bckbone. In this pper, we propose chnnel splitting technique to ddress the bove unconsidered issue. The contribution o our work minly lies in the ollowing points: esigning chnnel splitting technique to shorten both the link-lyer nd network-lyer hndo ltency. Proposing two designs or the splitting chnnel medium ccess control (MAC) in the wireless mesh bckbone network to improve the perormnce o both hndo nd dt throughput. III. PROPOSE ESIGNS IN THE WIRELESS MESH BACKBONE BASE ON CHANNEL SPLITTING We propose chnnel splitting technique or delivering the hndo signling pckets through split control chnnel in the wireless mesh bckbone. We use IEEE crrier sense multiple ccess with collision voidnce (CSMA/CA)- bsed MAC protocol to void collision in the chnnel. Single Chnnel Trnsmission Technique: In this design, both the RTS/CTS reservtion nd the trnsmission o dt pckets re crried out on the dt chnnel. The control chnnel is only used to trnsmit signling pckets, such s Agent Solicittion, Agent Advertisement, Registrtion Request, nd Registrtion Reply. All the dt pckets only compete on the dt chnnel. Thereore, the two types o pckets no longer ect ech other. This method is pplicble to the sitution when the totl number o hndos in the WMN is high nd seprte split chnnel is required to deliver the high volume o signling pckets to gurntee hndo dely. In ddition, i the chnnel utiliztion o both chnnels is high, high network throughput cn be chieved. H n d o e l y Number o hndo Fig. 4 Single Chnnel Trnsmission Br Grph In SCT design two networks re creted (Wi-Fi nd WiMAX) nd the hndo dely is clculted in ech network nd br grph is plotted using NS2. Figure 4 shows the single chnnel trnsmission br grph plotted between the number o hndo nd the hndo dely in the network. In the bove grph the red colour shows the hndo dely in the Wi-Fi network nd the green colour shows the hndo dely in the WiMAX network. The hndo dely is less in SCT design compred to trditionl hndo method. 2251

4 Interntionl Journl o Engineering Reserch & Technology (IJERT) H n d o e l y t T r i c Fig. 5 SCT Hndo ely Vs t Tric Figure 5 shows tht line grph is plotted between hndo dely vs. t tric in SCT design to show tht the loss o dt due to high hndo is less. Combined Chnnel Trnsmission: When n MR hs dt pcket to send, the MR irst checks the stte o the dt chnnel. I the dt chnnel is idle, the MR perorms the RTS/CTS reservtion process on the dt chnnel. However, when the dt tric lod is high in the wireless mesh bckbone, the dt chnnel my be in the busy stte most o the time. Under such situtions, our proposed CCT scheme is designed to mke use o the idle periods on the control chnnel to inish the RTS/CTS reservtion in dvnce; thereore, the next dt trnsmission cn be executed right ter the previous dt trnsmission. In our proposed CCT design, MRs cn determine to deliver the RTS/CTS reservtion pckets either on the control chnnel or on the dt chnnel dynmiclly, depending on the bckbone tric lod, thereby improving the overll chnnel utiliztion nd dt pcket ETE dely. This design cn utilize the dt chnnel with high eiciency becuse the time required to reserve the dt chnnel is consumed in the idle period o the control chnnel. Thereore, the RTS/CTS overhed on the dt chnnel is reduced, nd the overll chnnel throughput is improved. Thereore, the RTS/CTS overhed on the dt chnnel is reduced, nd the overll chnnel throughput is improved. The CCT design cn be pplied to the WMN where the hndo tric volume in the mesh bckbone is low, leving suicient idle periods on the control chnnel or dt chnnel reservtion. A suitble pseudo lgorithm re developed or this combined chnnel trnsmission technique nd the lgorithm is implemented in NS2 C++ coding. Using the pseudo lgorithm the dt tric in the network cn be improved nd 80% throughput is chieved. Hndo ely Fig. 6 Combined Chnnel Trnsmission Br Grph In CCT design two networks re creted (Wi-Fi nd WiMAX) nd the hndo dely is clculted in ech network nd br grph is plotted using NS2. In igure 6 Br grph is plotted between the number o hndo vs. hndo dely in the network using CCT design. In the bove grph the red colour shows the hndo dely in the Wi-Fi network nd the green colour shows the hndo dely in the WiMAX network. The hndo dely is less in CCT design compred to trditionl hndo method. Number o hndo Hndo ely Fig. 7 CCT Hndo ely Vs t Tric Figure 7 shows tht line grph is plotted between hndo dely vs. t tric in CCT design where the loss o dt due to high hndo is less. 2252

5 Interntionl Journl o Engineering Reserch & Technology (IJERT) IV. CONCLUSION In this pper, chnnel splitting technique is proposed to improve both the hndos perormnce in WMNs. We proposed hndo procedures using the chnnel splitting technique. In our design, the time or the link-lyer chnnel scnning process cn be reduced nd the contentions between hndo signling pckets nd dt pckets in the multi-hop wireless mesh bckbone is eliminted. In ddition, we proposed two trnsmission techniques in the wireless mesh bckbone to improve the overll hndo perormnce s well s the ETE dt perormnce. NS2 simultion results show tht the hndo dely, ETE dt throughput, nd ETE dely cn be improved by using the proposed chnnel splitting technique. REFERENCES [1] Mihil L. Sichitiu, Wireless Mesh Networks: Opportunities And Chllenges [2] MeshNetworks website. [3] Y.-S. Chen, M.-C. Chung, nd C.-K. Chen, eucescn: eucebsed st hndo scheme in IEEE wireless networks, IEEE Trns. Veh. Technol., vol. 57, no. 2, pp , Mr [4] C. E. Perkins, IP mobility support or IPv4, Request or Comments (RFC) 3220, Internet Engineering Tsk Force, Jn [5] R. Hung, C. Zhng, nd Y. Fng, A mobility mngement scheme or wireless mesh networks, in Proc. IEEE GLOBECOM, Nov. 2007, pp [6] S. Speicher, OLSR-FstSync: Fst post-hndo route discovery in wireless mesh networks, in Proc. IEEE VTC, 2006, pp [7] P. Kysnur, J. Pdhye, nd P. Bhl, On the eiccy o seprting control nd dt into dierent requency bnds, in Proc. 2nd BrodNets, Oct. 2005, vol. 1, pp [8] Y. Li, H. Wu, N.-F. Tzeng,. Perkins, nd M. Byoumi, MAC- SCC: A medium ccess control protocol with seprte control chnnel or reconigurble multi-hop wireless networks, IEEE Trns. Wireless Commun., vol. 5, no. 7, pp , Jul [9] S.Wu, C. Lin, Y. Tseng, nd J. Sheu, A new multi-chnnelmac protocol with on-demnd chnnel ssignment or mobile d hoc networks, in Proc. ISPAN, lls, TX, ec. 2000, pp [10] C. E. Perkins, IP mobility support or IPv4, Request or Comments (RFC) 3220, Internet Engineering Tsk Force, Jn [11] J. Xie nd X.Wng, A survey o mobility mngement in hybrid wireless mesh networks, IEEE Netw., vol. 22, no. 6, pp , Nov./ec [12] A. Mishr, M. Shin, nd W. Arbugh, An empiricl nlysis o the IEEE MAC lyer hndo process, ACMSIGCOMM Comput. Commun. Rev., vol. 33, no. 2, pp , Apr [13] I. Rmni nd S. Svge, SyncScn: Prcticl st hndo or inrstructure networks, in Proc. IEEE INFOCOM, 2005, vol. 1, pp [14] H. Wu, K. Tn, Y. Zhng, nd Q. Zhng, Proctive scn: st hndo with smrt triggers or wireless LAN, in Proc. IEEE INFOCOM, 2007, pp [15] S. Shin, A. G. Forte, A. S. Rwt, nd H. Schulzrinne, Reducing MAC lyer hndo ltency in IEEE wireless LANs, in Proc. ACM MobiWc, Sep. 2004, pp