A Local Mobility Agent Selection Algorithm for Mobile Networks

Transcription

1 A Local Mobility Agent Selection Algorithm for Mobile Network Yi Xu Henry C. J. Lee Vrizlynn L. L. Thing Intitute for Infocomm Reearch, 21 Heng Mui Keng Terrace, Singapore {yxu, hlee, Abtract The Mobile IP protocol ha been deigned to addre the problem of roaming between IP network. However, a a mobile node move between network, the ignaling overhead caue ignificant diruption to real time data traffic. The Localized Mobility Management (LMM) ha been propoed to enhance the handoff performance between network within the ame domain. By introducing the concept of Local Mobility Agent (LMA), a mobile node viiting a foreign domain i exempted from ending frequent addre update to it home agent and correpondent node, when it movement i limited to the viited domain. A multiple LMA are configured in a domain for redundancy, calability and load haring concern, LMA election become an iue. Thi paper propoe a new LMA election algorithm, Mobile Controlled Movement Tracking (MCMT). The objective of thi new algorithm i to dicover the optimal LMA in term of election tability and load balancing, by taking into conideration the mobility characteritic of the mobile node. Our analyi how that thi propoal can provide good upport for low latency handoff and load haring among LMA. Index Term Mobile IP, Localized Mobility Management, Local Mobility Agent, Internet, Wirele Network. I. INTRODUCTION Mobility upport in contemporary internetwork i a fundamental iue when thee network promie location independent ervice. No matter where a hot reide phyically, the network hould be able to identify it correctly with tranparent upport for communication above network layer. Mobile IP ha been propoed to addre the mobility iue in IP layer [1, 2]. When away from the home network, a mobile node regiter it new IP addre (care of addre) with the home agent. The correpondent node, which are unaware of the new location of the mobile node, end packet to it home network a uual. The home agent intercept thee packet and redirect them to the current care of addre of the mobile node through tunneling. Meanwhile, the mobile node may update the correpondent node with it new addre o that packet from the correpondent node can be routed directly to the mobile node after addre update. While mobile IP allow ubiquitou acceibility to a mobile node, performance in upper layer application upport i not o atifactory, epecially for QoS enitive communication. In baic mobile IP propoal, each time the mobile node move into a new acce network, a equence of ignaling take place before upper layer communication eion i retored into normal tranmiion. During thi interim, the mobile node complete link layer handoff, detect network alteration, configure it new IP addre, and end binding update to it home agent and correpondent node. Handoff latency in IP layer may caue noticeable diruption to ongoing tranmiion eion that all the packet ent to the mobile node are lot during thi interval. Congetion control mechanim of TCP degrade throughput further by mitakenly reducing the tranmiion window ize, having oberved packet lo. The baic mobile IP propoal alo incur high overhead on the network a every binding update meage mut travere the network all the way back to the home agent and the correpondent node even if the mobile node i involved only in local movement within a domain. Thee performance problem for mobile IP need to be addreed epecially in the wirele environment. Deployment of mall and dene wirele cell offer high aggregate bandwidth, but force frequent handoff for a moving node. To accommodate the mobile node with better upport for eamle handoff and alleviate network load a much a poible, extenion to the baic mobile IP are propoed. In IPv4 network, the foreign agent are organized into a treelike hierarchy to improve mobile IP handoff latency. In [3], all the foreign agent on the path from the mobile node to it home network keep an addre binding for the mobile node. Each binding point to the next hop leading to the preent location of the mobile node. When the mobile node change location, the addre update meage top at the foreign agent where a binding already exit, a the remaining hop are intact from the addre change. In [4], different mobility management trategie are employed repectively for local, intra adminitrative domain and global mobility. While local mobility i taken care of by link layer mechanim and global mobility i handled by the baic mobile IP, hierarchy of foreign agent i aumed to manage intra-domain movement of the mobile node. In IPv6 network, the concept of Local Mobility Agent (LMA) [5] i introduced that erve a a local home agent in the viited domain. In [6] the Mobility Anchor Point (MAP) i ued a a terminology equivalent to LMA. By deignating LMA within a domain viited by the mobile node, intra-domain movement of the mobile node i hidden behind the LMA o that it handoff i tranparent to the home agent and the correpondent node. Each time the mobile node change it point of attachment, it end a binding update meage to the LMA, wherea it globally perceived IP addre remain intact and valid for routing outide the domain. Therefore, handoff latency i reduced a binding update terminate at the LMA in local domain rather than at the home agent and correpondent node which may reide at the other end of Internet. Overhead introduced by location management i alo lower than that of the baic mobile IP. Intead of eparate binding update with the home agent and each correpondent node, one update with the LMA i enough to track the movement of the mobile node. Other approache to reduce IP handoff latency and packet lo include fat handoff [7], utilization of IP multicating [8, 9] and link layer handoff notification to IP layer [10].

2 In thi paper we tudy the localized mobility management approach in IPv6 network. To improve robutne and enable traffic haring, multiple LMA are typically deployed in a domain. Normally a mobile node doe not elect more than one LMA, becaue the ue of additional LMA introduce extra tunneling overhead when packet are routed to the mobile node. Thi paper attempt to addre the iue of electing one LMA in a domain with multiple LMA. The ret of thi paper i organized a follow. Section II decribe the related work and tate the problem to be tudied. Section III propoe a new LMA election algorithm, the Mobile Controlled Movement Tracking. Section IV invetigate thi new propoal with analytical and imulation reult. Section V conclude thi paper. II. RELATED WORK AND PROBLEM STATEMENT Two LMA election algorithm are een in literature. One elect the furthet LMA on the tranmiion path from the mobile node to it home network [6, 11] and the other make election by the preference et by each LMA [6]. An IPv6 neighbor dicovery extenion, the MAP option, i defined in [6] to dieminate LMA information throughout a domain. Two informational field are included in thi option for LMA election. The Ditance field record the ditance from the LMA to the mobile node. The Preference field indicate the willingne of the LMA to offer local regitration ervice. Every LMA inide the domain keep ending out it option to the mobile node periodically. For the furthet LMA election, the mobile node chooe to regiter with the LMA with the greatet Ditance field. Becaue thi one appear to be alway reachable in the long run, thi election minimize frequent regitration at the home agent and the correpondent node when the mobile node change it care of addre. For the preference election, the mobile node elect the LMA with the mallet value in the Preference field. However, the furthet LMA election trategy ha ome drawback. Firtly, the furthet LMA from the mobile node will mot likely be the gateway that connect the domain to the ret of the network. If every mobile node elect the furthet LMA, thi furthet one i likely to be overloaded a it i the ole entity reponible for all the mobile node in the domain. Secondly, if the mobility cope of the mobile node i only a limited area in the domain, it i not neceary to regiter at the furthet LMA. In thi cae, a nearer LMA will reduce regitration delay. For the preference baed LMA election, the unreolved problem i what factor decide value aignment for preference level. We propoe that LMA election follow the principle that the mot uitable LMA i the one which provide not-o-tranient regional regitration ervice and meanwhile reide near to the mobile node. For a mobile node that change acce network frequently, a relatively further LMA will take care of it mobility, while for a mobile node that i involved in limited mobility, a relatively nearer LMA i elected. In thi way, different mobile node may end up with different LMA election. Conequently, regitration load i ditributed to all the LMA in the Fig. 1. entry 1 (Gateway LMA) entry 2 entry n Lifetime Ditance IP Addre Ditance IP Addre Ditance IP Addre LMA advertiement, a new IPv6 neighbor dicovery option domain, avoiding overcrowding at the gateway LMA. Selection of a nearer LMA alo bring another performance advantage that update of new care of addre at the elected LMA can be completed fater. III. MOBILE CONTROLLED MOVEMENT TRACKING LMA SELECTION A new LMA election algorithm, Mobile Controlled Movement Tracking (MCMT), i preented in thi ection. Thi name implie two fact. Firtly, while network provide the information on LMA ditribution to the mobile node, it i the mobile node itelf that decide with which LMA to perform local regitration. Secondly, the deciion i baed on the movement of the mobile node o that the elected LMA i near to the mobile node and provide table ervice depite the movement of the mobile node. The MCMT operation require the mobile node to know all the available LMA on it tranmiion path toward the home agent, o a to elect the mot appropriate one. To achieve thi, we propoe to et up a LMA tree topology explicitly and ditribute relevant branch information to the mobile node. Therefore, in addition to LMA election, the MCMT trategy alo include LMA tree topology contruction mechanim to configure all the LMA of a domain into a tree tructure. A. LMA Tree Contruction We define a new IPv6 neighbor dicovery option named LMA Advertiement option to contruct the LMA tree. Thi option circulate with router advertiement meage to propagate LMA information throughout the domain. A illutrated in Figure 1, it contain three type of informational field, Lifetime, Ditance and IP Addre. TheLifetime field indicate validity duration of the originating LMA. The Lifetime field i followed by a number of LMA entrie, each compriing the (Ditance, IP Addre) pair. The IP Addre field give the IP addre of the LMA. The Ditance field record the ditance from the LMA of thi entry to the LMA that receive thi advertiement. Meanwhile, each LMA maintain a LMA lit locally that i a copy of the LMA advertiement. Thi LMA lit let each LMA know it own hierarchical poition. The gateway LMA initiate the tree contruction proce by ending out the firt LMA advertiement. Thi advertiement

3 contain only one entry. Upon reception of thi LMA advertiement at a downtream router, if thi router doe not act a LMA, it imply increment the Ditance field by 1 and forward thi advertiement onto other network interface. If thi router i a LMA, it examine whether a local LMA lit already exit. If not, the lit i etablihed uing the information carried in thi advertiement. If a local lit exit already, comparion i made between the ditance recorded in the received advertiement and that in the local lit to find out which one repreent a horter path from the gateway LMA. When the advertiement carrie a horter path, the local lit i updated with the content of the advertiement. Otherwie, the local lit remain intact. After a LMA ha updated it local lit, thi LMA will generate a new advertiement to inform it neighbor of thi change. In the new advertiement, thi LMA add in itelf a the lat entry and increment the Ditance field of all the other LMA by 1. When the LMA advertiement propagate away from the gateway LMA, more LMA are dicovered and the length of the advertiement increae gradually until the acce router i reached. Auming that none of the LMA advertiement i lot, every LMA will eventually etablih a local lit that repreent the hortet path from the gateway LMA. Each acce router alo keep a local LMA lit, which include all the LMA on the hortet path from the gateway LMA to the acce router itelf. The Lifetime field help to detect network change, uch a LMA failure and link diruption. Every LMA end out advertiement periodically o that all it neighbor are continuouly informed of it reachability. If advertiement from a LMA i abent for a time duration indicated by the Lifetime field in the lat received advertiement, thi LMA i deemed to be unreachable. All thoe affected LMA will tart to liten to other advertiement to find out another hortet LMA lit. B. LMA Selection Acce router periodically end out LMA lit together with router advertiement. From thi lit, the mobile node can find all the LMA on the path from the gateway to the acce router, a well a their repective ditance. The mobile node can alo requet the LMA lit from the acce router actively intead of waiting for unolicited announcement. When the mobile node enter a new domain, it elect the gateway LMA by default. The mobile node regiter with the gateway LMA uing local care of addre and regiter with the home agent and correpondent node uing the IP addre of the gateway LMA. Then the mobile node begin to earch for a nearer LMA to replace the gateway LMA, if a nearer LMA i more uitable for it mobility pattern. For thi purpoe, the mobile node record all the LMA advertiement received duringapredefined period called the earch interval. At the end of earch interval, the mobile node find out the LMA that have appeared in every LMA advertiement and the one nearet to the mobile node i elected to replace the gateway LMA. In cae that the mobile node i involved in limited mobility within a fraction of the domain or it move very lowly, it i poible for the mobile node to locate a new LMA different from the gateway LMA. Then the mobile node regiter it local care of addre at the newly elected LMA and regiter the IP addre of thi newly elected LMA at the home agent and correpondent node. After that the mobile node tart a new round of earch again. When the mobile node move beyond the coverage of the elected LMA, it will immediately detect thi by noticing that the erving LMA i abent in the latet received LMA lit. A new LMA mut be elected from the latet LMA lit to take over the previou erving one. The mobile node identifie the new LMA to be the one that i almot the ame ditant away a the previou erving LMA. If mobility doe not change after location tranfer, thi peer LMA i the mot appropriate choice, a the mobility ha already been correctly reflected by the previou election. However, a new earch till tart immediately after thi new LMA i elected. If mobility actually change after location tranfer, at the end of thi earch interval either a further LMA or a nearer LMA will be located, depending on the new mobility pattern. When the mobile node change LMA election, the regitration of new LMA IP addre at the home agent and correpondent node may reult in long delay. Before regitration meage i received, all packet ent out from the home agent and correpondent node are directed to the previou LMA and lot there. To reduce packet lo, each time the mobile node elect a new LMA, it alo regiter the new LMA IP addre at previou LMA to redirect the in-flight packet to the new LMA. Thi regitration i not permanent, a the in-flight packet tream lat for only a hort duration approximately equal to the round trip time from the mobile node to the home agent and correpondent node. Practically, thi regitration can expire automatically in a few econd, which hould already be long enough o that mot in-flight packet will not be lot. IV. PERFORMANCE ANALYSIS Next, we tudy the performance of MCMT a compared to the furthet LMA election. Dicuion mainly focue on two performance apect, regitration delay and load balancing. A. Regitration Delay When the mobile node change acce network and regiter the new care of addre at LMA, horter ignaling delay can be expected when a nearer LMA i elected. If the mobile node i communicating with any correpondent node during thi interval, the regitration delay can be tranlated into packet lo. Intuitively, le packet lo will be reulted from election of a nearer LMA than the furthet one. We tudy thi performance apect by imulation. The Network Simulator (NS-2) [12] i ued a imulation tool. The imulation topology i depicted in Figure 2. In real-world cenario, there might be intermediate network between neighboring LMA. In our imulation topology, all thee intermediate

4 CN 200m LMA 0 (Gateway LMA) 8m LMA 1 6m 6m LMA 2 LMA 3 4m 4m 4m 4m LMA 4 LMA 5 LMA 6 LMA 7 2m 2m 2m 2m 2m 2m 2m 2m LMA 8 LMA 9 LMA10 LMA11 LMA12 LMA13 LMA14 LMA15 5Mbp 1m MN Mobility Scope 1 Mobility Scope 2 Mobility Scope 3 Contant Movement Packet Lo Ratio in Every 1 Minute Time Slice Mobility Scope 1 Mobility Scope 2 Mobility Scope Simulation Time (min) Fig. 2. Simulation topology Fig. 3. Packet lo ratio in different mobility cope, 4 min earch interval network are reduced to a ingle link. Therefore, the delay aigned to each link include propagation delay, tranmiion delay and proceing delay on all the network in between. Conidering the router near gateway are likely to be loaded more heavily than thoe near the acce network, we aign the delay value for each link in a decreaing order from the gateway LMA to the acce router to reflect uch difference in proceing delay. For all wired link, bandwidth of i aumed. Becaue the lat hop to the mobile node i wirele link that might be a bottleneck on the path, bandwidth of 5Mbp i aumed for the link between the mobile node and the nearet LMA. The correpondent node keep ending in packet at contant rate of 1Mbp with packet ize of 128 byte each. When handoff take place, we aume that the mobile node requet the LMA lit from the new acce router immediately. A delay of 10m i ued to model the LMA lit acquiition proce. Firtly, we let the mobile node move in different mobility cope. For all three mobility cope, the mobile node change acce network every 30 econd. In cope 1, handoff happen between LMA8 and LMA9. In cope 2, handoff occur between LMA8, LMA9, LMA10 and LMA11 in turn, and then in revere order. In cope 3, handoff occur from LMA8 to LMA15, then in revere order. A earch interval of 4 minute i ued. For each mobility cenario, packet lo in every 1-minute time lice i counted for both the MCMT algorithm and the furthet LMA election. Figure 3 give the packet lo ratio of the two trategie. A in the beginning 4 minute MCMT elect the furthet LMA a default, there i no performance gain over the furthet LMA election trategy. At the end of 4 minute, depending on the repective mobility cope, MCMT locate a nearer LMA to replace the furthet one. After that, packet lo during handoff i reduced under MCMT algorithm. The mot ignificant packet lo reduction occur in mobility cope 1, becaue thi one elect the nearet LMA among the three cae. Then, we let the mobile node move in contant peed without direction change to invetigate the effect of movement peed. The topology map i wrapped around o that when the mobile Fig. 4. Packet Lo Ratio Dwelling Time Under Coverage of the Nearet LMA (min) Packet lo ratio in different peed, 4 min earch interval node move out of the coverage of LMA15, it enter the map again at LMA8. Dwelling time under coverage of the nearet LMA i ued a equivalent meaurement for peed. Figure 4 how the packet lo ratio a a function of different dwelling time value. When the mobile node move very fat, ay, dwelling time i le than 1 minute, at the end of earch interval, the mobile node goe acro more than half of the coverage of LMA1, o LMA1 i decided to replace the gateway LMA. A dwelling time increae, the mobile node will elect even nearer LMA gradually, o the packet lo ratio tep down. When dwelling time i longer than 4 minute, earch interval will alway elect the nearet LMA and the packet lo ratio reache the lowet value. The packet lo ratio i determined by a few factor. Beide the local care of addre regitration delay and LMA lit acquiition delay, each time the mobile node change LMA, the ignaling delay of new LMA IP addre regitration at previou LMA caue ome additional packet lo. Comparion between Figure 3 and Figure 4 how thi phenomenon. In Figure 3, when the mobile node move in the mobility cope 2, LMA2 i elected. In Figure 4, when the mobile node move with dwelling time between 1 and 2 minute, it elect LMA2 too. But in thi latter cae, the mobile node will witch between LMA2 and LMA3, therefore reulting higher packet lo ratio

5 TABLE I DESCRIPTION OF A TYPICAL MOVEMENT SCENARIO Duration Movement Decription 30 min mobility cope 1, 50 ec dwelling time 30 min contant movement, 40 ec dwelling time 30 min mobility cope 1, 50 ec dwelling time 30 min contant movement, 20 ec dwelling time 30 min mobility cope 1, 50 ec dwelling time 30 min contant movement, 10 ec dwelling time 30 min mobility cope 1, 50 ec dwelling time Fig. 5. Packet Lo Ratio in Every 10 Minute Time Slice Simulation Time (min) Packet lo ratio in different time lice, 1 min earch interval than in Figure 3. Seen in Figure 3, the packet lo ratio i 0.38 after LMA2 ha been elected, wherea the ratio i 0.46 in Figure 4. Neverthele, a the ignaling delay for regitration at previou LMA i much horter than the round trip time from the mobile node to the correpondent node, mot in-flight packet can be redirected uccefully and the packet lo ratio i till alway maller than 1. Therefore, even if the mobile node move irregularly and goe beyond coverage of the currently elected LMA, the MCMT algorithm till doe not perform wore than the furthet LMA election. Finally, we preent the imulation reult of a more typical movement cenario. Table I decribe thi movement cenario. The reult i depicted in Figure 5. A the mobile node change it mobility pattern over time, LMA election change accordingly, o the packet lo ratio varie over time. Each ratio conform well to our dicuion on the previou two figure. B. Load Balancing Becaue each mobile node bae it LMA election on it own mobility feature, intuitively, MCMT ditribute the regitration load to all the LMA inide the domain. Therefore, better load balancing i achieved compared to the furthet LMA election. However, the length of earch interval play an important role in LMA election. To balance the load a evenly a poible among all the LMA regardle their ditance, a pecial cae i tudied, in which we make the following two aumption. Firt, every n LMA of the ame ditance from the mobile node are under coverage of the ame parent LMA. In Figure 2, n i equal to 2. Second, all mobile node move contantly with the dwelling time under coverage of the nearet LMA uniformly ditributed over [0, T max ]. According to the MCMT algorithm, when the dwelling time fall into the interval [, T max ], the nearet LMA will be elected, where denote the length of earch interval. When dwelling time fall into the interval [ n, ], the econd nearet LMA will be elected, and o on. The election i ummarized into the following equation. { Nearet LMA <tdwl <T max kth nearet LMA <t n k 1 dwl < (1),k 2 n k 2 Known from Equation 1, when k 2, the number of mobile node that elect the kth nearet LMA i ρ( ), and n k 2 n k 1 that elect the (k +1)th nearet LMA i ρ( ), where ρ n k 1 n k i the probability denity. The ratio of the two group are given in Equation 2. ρ( ) n k 2 n k 1 ρ( = n (2) ) n k 1 n k A the number of LMA in the kth nearet level i n time the number in the (k +1)th nearet level, Equation 2 indicate that the average load on individual LMA i the ame on both level. Therefore, to balance the load on all level, we only need to take care of the nearet LMA. Let the average load on individual LMA in the nearet level be the ame a that in the econd nearet level, we have Equation 3. ρ(t max ) n = ρ( n ) (3) Then the earch interval i determined by Equation 4. = T max n In addition, if mobile node enter the domain at a contant arrival rate, then every LMA on the ame ditance level will alo be evenly loaded, o that all the LMA inide the domain will have the ame load. In more realitic mobility cenario, mot mobile node do not move in high peed all the time. Intead, they tend to tay omewhere and change their location occaionally. In thi cae, mot mobile node will elect the LMA in the lower level of the LMA hierarchy. A the number of thee LMA far exceed that near the gateway LMA, the major portion of regitration load i therefore ditributed, alleviating the load on the gateway LMA. C. Overhead Dicuion The LMA tree contruction and LMA advertiement meage introduce ignaling overhead. However, thi overhead doe not exceed that introduced by the furthet LMA election propoed in [6]. In [6], the LMA information i propagated in a imilar way, and furthermore, a mobile node probably receive (4)

6 the advertiement from all the LMA in the domain. But in the MCMT trategy, only the advertiement on it regitration path are received. Therefore, the number of LMA advertiement tranmitted on the wirele link i reduced. If the mobile node can requet LMA lit actively, the ignaling overhead on the wirele link can be reduced even more. In thi cae, the LMA lit i delivered to the mobile node only at requet when handoff take place, eliminating unneceary announcement when the mobile node doe not change acce network. D. Comparion with Other Micro-Mobility Protocol There are many micro-mobility protocol een in the literature. Beide deployment of local mobility agent in a domain, other technique, uch a fat handoff [7] and IP multicating [8, 9], have alo been dicued widely. The MCMT algorithm i orthogonal to them and, therefore, can be integrated with thee technique to reduce packet lo further. Among the approache that aume employment of mobility agent, equential tunneling along multiple mobility agent [3] and hot pecific routing [13, 14] are the two major method propoed to track the local mobility of the mobile node. However, both of them require routing information to be recorded in multiple node, the mobility agent in the former one and the router in the latter one. On the contrary, in the MCMT only the elected LMA i involved, which introduce le routing expene. Another problem with equential tunneling and hot pecific routing i that the gateway mobility agent or router mut keep a routing entry for every viiting mobile node, while the MCMT can potentially decentralize the load from the gateway. The torage pace and meaging required by the MCMT for LMA tree contruction are extra expene that are not preent in the other protocol. However, thi overhead i independent of the number of mobile node in the domain. In contrat, in equential tunneling and hot pecific routing, the number of routing entrie in mobility agent and router increae quickly when the mobile node population expand. Intuitively, there i le calability concern in the MCMT than in the other two. REFERENCES [1] C. Perkin, IP Mobility Support for IPv4, IETF RFC3220, Nokia Reearch Center, January [2] D. B. Johnon, C. Perkin, Mobility Support in IPv6, IETF Internet Draft, work in progre, Nokia Reearch Center, March [3] D. Forberg, J. T. Malinen, J. K. Malinen, T. Wecktrom, M. Tiuanen, Ditributing Mobility Agent Hierarchically under Frequent Location Update, in Proceeding of Mobile Multimedia Communication [4] R. Cacere, V. N. Padmanabhan, Fat and Scalable Handoff for Wirele Internetwork, ACM MOBICOM [5] C. William, Localized Mobility Management Requirement for IPv6, IETF Internet Draft, work in progre, DoCoMo USA Lab, November [6] H. Soliman, C. Catelluccia, K. El-Malki, L. Bellier, Hierarchical MIPv6 Mobility Management, IETF Internet Draft, work in progre, Ericon, July [7] G. Dommety, Fat Handover for Mobile IPv6, IETF Internet Draft, work in progre, March [8] C. Catelluccia, A Hierarchical Mobility Management Scheme for IPv6, IEEE International Sympoium on Computer and Communication [9] H. Balakrihnan, S. Sehan, R. H. Katz, Improving Reliable Tranport and Handoff Performance in Cellular Wirele Network, ACM Wirele Network, pp , iue 1, [10] C. S. Wu, C. W. Cheng, N. F. Huang, G. K. Ma, Intelligent Handoff for Mobile Wirele Internet, ACM Mobile Network and Application, pp , iue 6, [11] V. L. L. Thing, H. C. J. Lee, Y. Xu, Deign and Analyi of IPv6 Local Mobility Agent Dicovery, Selection and Failure Detection, The Fourth IEEE Conference on Mobile and Wirele Communication Network, September [12] The Network Simulator, [13] A. T. Campbell, J. Gomez, S. Kim, A. G. Valko, C. Y. Wan, Z. R. Turanyi, Deign, Implementation, and Evaluation of Cellular IP, IEEE Peronal Communication, pp , Augut [14] R. Ramjee, T. La Porta, S. Thuel, K. Varadhan, HAWAII: A Domain-baed Approach for Supporting Mobility in Wide-area Wirele Network, IEEE International Conference on Network Protocol, pp , V. CONCLUSIONS A new LMA election algorithm, Mobile Controlled Movement Tracking, ha been propoed in thi paper, which take mobility pattern into conideration for LMA election. By contant monitoring of node mobility, thi algorithm attempt to locate a LMA that i table and a near a poible to the mobile node. A a reult, the elected LMA provide upport for low latency handoff and load balancing. When mobility characteritic change over time, thi algorithm adaptively dicover new LMA that i more uitable for the new mobility pattern. Simulation and analytical reult how thi new algorithm outperform the furthet LMA election in term of reduced regitration delay and balanced regitration load. Compared to other micro-mobility management approache, thi propoal i alo more calable to upport large number of mobile node.