TPRLM: Time-based Probabilistic Relational LocationManagement Scheme for Wireless Cellular Networks

Sourav Sahal, Mainak Mukherjee2, Avik Ranjan Paul2 and Sarmistha Neogy3

'Dept. of Information Technology, Bengal Institute of Technology, Kolkata, India, sourav itl@yahoo.com2Dept. of Electronics & Communication Engg., Bengal Institute of Technology, Kolkata, India

mukherjee.mainakgrediffmail.com, aveek888paulggmail.com3Dept. of Computer Sc. & Engg., Jadavpur University, Kolkata, India, sneogygcse.jdvu.ac.in

Abstract based location management are critically analyzed to detecttheir advantages and future development scopes. Then we

Locating mobile nodes and delivery of inward calls to that node in havenprop s a scheme na med t where Throughwireless cellular networks, in spite of extreme mobility of the nodes, . . a scheme. 'is a challenging issue. Fast and error-free delivery of packets to invocation of time-based probabilistic relational locationperfect destination with good performance in wireless environment is management, the paging and location update cost, networkextremely difficult to attain. Several available location management bandwidth wastage, location update and paging delay etc. areschemes incur huge location update cost, paging cost and network attempted to reduce. The interactivity and performance ofbandwidth wastage in attempt to achieve it. They also offer location administration are tried to decrease here.significant location update delay and paging delay. Interactivity and The remaining part of the paper is organized as follows:great efficiency are also lacking. In this paper, the framework of a Section II offers the basic ideas on location management inscheme TPRLM is proposed. This scheme combines relational level- context of mobility handling. Section III presents a report ofbased coverage area management with organized Informing Cells and the survey of previous works in related areas for cellulartime-based probabilistic priority calculation based on inward call networks and section IV describes the overall status of thearrival rate of any node. The scheme tries to attain cost-effectiveness, already proposed schemes. Section V mentions the basicreduced location update delay and paging delay. There is also scope ,for interactivity and improved performance without complexity. objectives of our approach. In section VI, the framework of an

improved scheme TPRLM is proposed along with its basicI. INTRODUCTION concept, algorithm, illustration etc. Finally in section VII, we

conclude with the future development scopes of our work."Working while moving" is an extremely essentialrequirement nowadays. But error-free delivery of packets to II. LOCATION MANAGEMENT: BASIC CONCEPTSperfect destination in network consisting of mobile hosts istruly challenging. The problem of maintaining end-to-end Location Management is an interesting and immenselyconsistent service for wireless networks increases with the necessary service for superior performance of frequentlyincrease in number of nodes in the network or boost of random moving nodes in wireless network. This enables any mobilemobility of nodes. The approximate locations of any node can node in wireless network to know the approximate location ofbe obtained through use of some technique. The movement of any mobile node so that it can send the packets to the actualany node may be tracked also. The source node may ask for destination node in spite of its movement. In locationthe approximate location of the destination node from the management, the success of sensing the mobile node location,location server who contains updated information. The source movement detection of that node etc. performs major role innode, at receipt of location of destination node can then start delivery of packets to accurate destination. Hence locationrouting packets to it. management basically consists of three steps: locationSeveral location management strategies are available for registration (selecting location servers, authenticating andwireless cellular networks. But the paging and location update periodically updating location server database withcost is not too small. The network bandwidth is wasted also. approximate location information), location maintenanceThe location update time and paging delay has scope to be (maintenance of location database by cleansing it periodicallyfurther improved. The increase of interactivity is also very for better performance and database consistency) and callmuch required. The overall performance of location delivery through location discovery (finding out themanagement has provision for supplementary enhancement approximate location of the destination node through querywithout making the procedure extra ordinarily complex. made by the source node in the location server database andIn this paper the basic concept of location management along delivery of call to the destination node).with several types of locating any node in wireless Any sender mobile node can locate the destination mobileenvironment are discussed. The basic ideas of various scheme node in mainly two ways: through continuous locationproposals related to location update, paging and mobility agent tracking or through location searching immediately before

interaction. The methods are depicted in the figure 1 below.

1-4244-0614-5/07/$20.00 ©2007 IEEE.

Locating any Mobile arranged into several categories [1, 4, 5] that is reflected inNode figure 2 next. Location update schemes can be local or global.

They may also have several subcategories.Local Location Update Scheme: Here any particular mobile

Continuous Location Location Searching user can choose the time and area for itself for initiation ofTracking Immediately before Interaction location update process. It is not dependent on the location

update areas of other mobile users. These strategies can beFigure 1: Techniques to locate any mobilenode divided into two subcategories: static and dynamic. We shall

Location ypdate SchemesFor continuous location tracking the mobile node or the Locationlpdate Schemes

mobility management system has to constantly sense locations Local Globalof nodes in the network. The movement of any node isdetected and maintained in some storage area for future use.For short-timed asynchronous communication where several Static Dynamic Static Dynamicsource mobile hosts send packets frequently to any destinationmobile node, the continuous location tracking method is Loc tion Retortingsuitable. In such a scenario the mobile nodes have to Area-based Center-basedcontribute to the location management system by specifyingthe frequently changing locations in order to keep the systeminformed or the mobile node itself must be responsible for Time Movement Topology Load-continuous tracking of node location. Depending on the -based -based -based sensitivechange of locations of mobile nodes location updates are madehere. Interaction between source node and destination node Path Report Per-user Profile Distancemay commence on successful detection of the location of the -based based -based -baseddestination mobile node at that time. Figure 2: Several location update schemes in organized mannerIn case of location searching immediately before interaction,the location of any mobile node is not constantly tracked. This call them static local and dynamic local location updatemethod of locating any mobile node is appropriate for long- schemes respectively for better characterization. They areterm peer-to-peer communication. Paging process can be used discussed below.here to find out the approximate location of any mobile node.The network coverage area is divided into several location Static Local Location Update Scheme: In these schemesareas. When a call is to be processed the destination mobile the network is assumed to consist of explicit cells or areasnode is found out through paging. The mobility agents may be where location updates occur when any new mobile nodeused in sensing the location of any mobile node directly before visits that area. The generation of location updates are ofany communication. static nature, since the cells or areas for generating

III. LOCATION MANAGEMENT IN CELLULAR NETWORK: A location updates are preset and do not change dependingCONCISE REVIEW OF THE PREVIOUS RELATED WORKS on the movement patterns of the mobile nodes. In

individualized location area (LA) update scheme [4, 8],

There are various proposals related to managing locations of the location update takes place when any mobile nodecomes into a pre-assi ned set of location areas.mobile nodes in cellular environment. We have studied the a g

, . , * Dynamic Local Location Update Scheme: In this type ofbasic concepts of such schemes and presented a criticalanalysis of our survey in this paper. Any mobile node can be *ocation update schemes, the updating of locationlocatedin cellular networks basically in two ways, as have information occurs based on the movements of the mobileloctein celua newok baialntowy, as have nodes instead of any pre-defined set of location areas. We

been specified in section II. Here we have reviewed the areas.. . ~~~~~~nowdiscuss several dynamic local location updateof location update, mobility agent and paging in separate schemes below:subsections.

A. Location Update Schemes o Time-based Strategy: Several time-based strategies [4,5, 6, 9, 10] are available where consecutive location

Thisisa procedure through which any mobile node makes its updates occur using fixed or variable time intervals (theThis is . , ,,., ,1interval is calculated differently in different schemes.latest location known to the system. Here one mobile node canhelp the network to updlate its dlatabase containing location tm-ae cee[] hr oainudtsaedninformation of the mobile nodles by messages. Thne updating OfI

* * r * r 1 1 1 1 1 1 ~~~~~byany mobile station periodically every T amount oflocation information content Of that database helps the systemtieBuhrealtouncsayuptsaetobto deliver any call to the dlestinedl mobile node in spite Of itsimmns mbiit. Th loato upat scee ca be performed independent of movement of the nodes.

Some enhancements are found in the timer-based cost is little. But this scheme is too straightforward forscheme proposal [9], where the time interval between dealing with practical location management oftwo consecutive location updates is not a fixed time nowadays.interval like the previous approach. Here an attempt is o Load-sensitive Strategy: In [35], the deployment ofmade to reduce the average cost of updating location non-utilized channel bandwidth is proposed forinformation through calculating maximum waiting time generating queries about the node location. This schemebetween two successive location update operations. But truly decreases the location management cost. But inthe improvement achieved is not very much than the frequently moving environment this scheme does notother. perform up to mark.In time-based, dynamic mobile user location update o Profile-based Strategy: There are several mobile nodescheme [10], the decision about the location update user profile-based schemes [4, 31, 32] available astime is taken by the mobile node dynamically based on surveyed below:the node movement pattern in the network and the In one profile-based strategy [31], two approaches,frequency of inward call. A location update occurs if based on maintenance of user movement pattern asthe paging cost to serve any inward call to it is greater mobile node user profile, are offered. In first approach,than the cost of location updating. This time-based the long-standing information related to location areasdynamic location update scheme shows improvements and the user location probability in that area is saved forin performance compared to the fixed time-based further need. If the mobile node does not visit any newlocation update scheme. But from overall point of view location area (i.e. not stored by system) in anyof location management performance, this scheme fails particular time, the location updating is not performed.to put up to requirement. On appearance of inward call destined for the mobileWe discuss the following techniques together below. node, the location area with maximum node location

o Path Report-based Strategy: LeZi-Update scheme [34] probability for any particular time, as saved by thefalls into this category since here the movement path of system, is paged. If not found, the stored location areaany mobile node is maintained based on reports given with next highest node location probability is paged.by the nodes. Path-report is delivered if the movement The first approach definitely diminishes the cost ofpath is not already stored. During inward call delivery location updating through storage of locationto that node the probable path is estimated using information. The second approach keeps track of long-previously stored movement paths of that node. standing as well as little or medium-standing actionsLocation update cost and paging cost is small here. But also to reduce the location management cost, whichthe probable path estimation requires some more necessitates more storage space.advancement. In another profile-based strategy [32], the parameters

o Movement-based Scheme: There are several movement used for defining the profile of any mobile node are the-based [4, 6, 46] schemes where location updates are total occurrence of cell switches performed by any nodemade based on mobile node movement. and the average amount of time of node attendance inIn classical movement-based scheme [6], any mobile every cell. The maintained profile helps the system tonode increments a counter value on crossing of cell dynamically produce the location areas with estimationborder and location is updated and counter value is of the probability for the presence of any mobile nodereset on attaining of the counter value any predefined there. The location is updated only if the node visits anyvalue M. The scheme is truly very easy. But the paging new area that is not already saved. On appearance ofcost is needed to be reduced, since for inward call inward call destined for any mobile node the pagingdelivery to any node here, the system has to page every initiates from the saved area where node attendancecell within a space ofM from the lastly updated cell. time is maximum. If found, others are not paged; elseIn an enhanced movement-based scheme selective area with second highest node presence time is pagedpaging process is proposed for decreasing the total and so on. The location update cost and paging costlocation management cost of system. The improvement here are not big. But if any node switches cellsattained through is small. randomly with short span of presence in any cell, the

o Per-user based Strategy: In this type of approach [47] total location management cost increases.the location updates are performed dynamically based o Distance-based: Various distance-based schemes [1, 4,on the movement types or some other information of 5, 6, 12, 13, 14, 15] exist. We analyze them below:individual mobile nodes. The performance of this easy The simplest one is the distance-based location updatescheme is better than static ones. scheme [6], where location is updated when the

o Topology-based Strategy: In this scheme [33] the distance from the previous updating location to recentpresent location of any mobile node can be determined position attains a preset distance threshold D. It showsusing the previous and present location of that node. improved performance as compared to several schemesThe location is updated only if the previous location is through limiting the search area etc. But this scheme isvarying from present location. Here location update

very simple in terms of coexistence with several to uphold only two most currently stayed location areas.mobility patterns of nowadays. If the movement of the mobile node is limited toAnother distance-based location update scheme [12] currently visited cells most of the times, this schemeemploys selective paging in addition to simple distance- offers very good result.based concept with D. Here the area with radius D is o Reporting Center-based Scheme: This strategy [4, 30]partitioned into sub-areas where polling is done one-by- employs some chosen cells from the system coverageone to find any new mobile node. This scheme shrinks area as reporting centers which are used by the mobilethe average total cost of location update and paging as nodes as updating points of location information. Anycompared to the previous one. However it complicates mobile node, entering any newer reporting center area,the total management. updates its location information. The reporting center-In look-ahead strategy for distance-based location based concept is balanced and organized. But thetracking [13], optimal future cell is searched so that it paging here is costly enough because all the cells nearmay be notified during location update. Here the the currently updated reporting center are paged infrequency of updating location information is order to locate any mobile node before delivery of anyconsiderably decreased. And it improves the location inward call destined for it.management system performance marginally.The predictive distance-based mobility management * Dynamic Global Location Management Scheme: In thisscheme [14], attempts to predict the future location of category all mobile nodes update location information inany mobile node on the basis of its most recent position identical set of cells on the basis of the mobility patternsand velocity. It enhances the performance of the of the nodes. One example of this type of strategy is time-location management as compared to simplistic varying location area strategy [4, 18], where globaldistance-based approach. But the prediction is location updates are performed with variable interval. Itapproximate. performs better than fixed time-based location updateIn [15], distances are represented using coordinate approach. But the improvement achieved is little.systems to improve cell addressing process for locationmanagement. But it helps in methodical calculation B. Mobility Agent-based Schemesprocess only.

Global Location Update Scheme: Here updating is carried Mobility agents (namely home agent and foreign agent) [19,out in identical set of cells by all the mobile node users. It is 20, 21, 22] aid in movement of any mobile node from onenot done for any single mobile user. network (home network) to another (foreign network) and stillIt can be either static or dynamic. maintain connection with the previous network. Several* Static Global Location Management Scheme: Here protocols that use mobility agent-enabled location

location updating occurs for predefined set of cells by all management are surveyed briefly below.the mobile nodes. It can be of two flavors as mentioned Mobile IP, Mobile IPv6 etc: In MIP [19, 20, 21, 22], thebelow: CoA (Care of Address) helps in locating any mobile nodeo Location Area-based Scheme: There are various moved from its home network to any foreign network. CoA

location area-based approaches [1, 4, 5, 6, 16, 17]. may be generated using foreign agent (FA) in foreignIn fundamental location area-based scheme [6], the network. The home agent (HA) can maintain and update thenetwork coverage range is divided into location areas MIP registration table. MIPv6 [3, 22, 36] is advanced(LAs) in a way to decrease the costs for location update version ofMIP to work with IPv6. The fundamental conceptand paging. Any mobile node updates location is still present nowadays in spite of several advancements.information in case of switching from one LA to But decreased power consumption, advanced QoS etc. areanother. But for mobile node that frequently switches required.from one LA to another, staying very short time in any CIP: In Cellular IP[3, 22, 37, 38] different access points inparticular LA, the overhead for location update various cells are connected through Gateway Router andtherefore increases significantly. offers fully static nodes, repeatedly moving nodes andThe selective location update strategy [16] attempts to infrequently moving nodes very good location managementsolve the aforesaid problem by updating location performance. But packet loss rate is not little here.information only on entering some pre-determined set HMIP and HMIPv6: In Hierarchical MIP [3, 22, 39] theof cells based on the movement patterns of the mobile hierarchical arrangement of FAs enables the Gatewaynodes. But for high user location probability and high Foreign Agent at root to track the movement of the mobileincoming call appearance rate the performance may be nodes at leaves of the hierarchy. The paging facility andmarginally better over others. hierarchical structure aid in improvement of performance.In the context of location area-based approaches we like But it suffers from scalability problem.to mention another algorithm, named Two Location IDMP (Intra-Domain Mobility Management Protocol):Algorithm (TLA) [17], which attempts to decrease the In this lightweight scheme [22, 40, 41] node location islocation update cost through allowing any mobile node managed in spite of their mobility through using several

Subnet Agents in several subnets connected to the root the probability is identical). The location probability of(Mobility Agent). Here use of modular approach, paging mobile nodes in the inner ring cells are greater than equal toand two dynamically autoconfigured CoAs reduces the that of outer ring cells and the inner rings contain lesserpower consumption and packet loss. But it needs to be a bit number of cells than outer rings. Any particular mobile nodemore secured. is searched here starting from inner ring cells and continuingTeleMIP: Telecommunication Enhanced MIP [22, 42, 43] toward outer ring cells. The organized management of theemploys a two-tier hierarchical structure with several GFAs coverage area absolutely advances the location managementat root for mobility management. Scalability is a very good process here. But in real life scenario it is very difficult toadvantage for it. But as it makes use of MIP for global find many mobile nodes with such ordered node locationmobility management, the drawbacks of MIP distresses the probability.efficiency of it. Uniform Paging Scheme: It is a very simple scheme [5,TLMM and TLMIPv6: Three Level Mobility Model [22, 26] where the number of divisions of every paging area is44] is a three-layer scheme using Global Mobility Agents at roughly the same. This reduces the complexities of theroot level for internetworking, Mobility Agents at middle management process, but cannot decrease paging delay.layer for managing intra-domain mobility. Three Layer Intelligent Paging Strategy: This scheme [5, 27] employsMobile IPv6 scheme [22, 45] is enhanced version ofTLMM multi-step method for locating any moving mobile node. Onfor working with IPv6. Employment of three CoAs for three appearance of any inward call, the destined mobile node islayers helps in better location management. The signaling located through mapping the paging area within the locationload here is less. area on the basis of moving speed of node, node state, rate

of inward call appearance to that node and its mobilityC. Paging Schemes pattern. Here the mapping process aids a lot in finding the

exact paging area of any mobile node within the coverageThe location of any mobile node can be found out before area. Signaling overhead is not huge here. But repetitiveinteracting with that node through paging. Paging aids in call paging failures can result in increase in paging cost here.delivery process by locating any mobile node, in spite of itsmobility between cells, on the basis of location information IV. CRITICAL ANALYSIS OF THE OVERALL STATUS OFpresent in the system. Several paging schemes are present as LOCATION MANAGEMENT SCHEMES IN CONTEXT OFstudied below: MOBILITY HANDLING

Sequential Paging Strategy: In this strategy [23], thelocation area is divided into sequentially numbered cells After studying various location management schemes fordepending on the location probability of mobile node in the cellular networks either continuous location tracking orcells. This strategy is well organized, but the paging cost searching location immediately before interaction, we presenthere is more. a brief summary of our survey below.Reverse Paging Scheme: This scheme [5, 24] attempts to The schemes attempt to decrease the signaling trafficreduce the cost of paging through dividing the service area overload, location update or paging cost and delay ininto several partitions and assuming the probable location of communication. Efficient coverage area partitioning,any mobile node from another one is little. But this improvement of paging techniques, reduction of the number ofassumption is not always practical. location updates, improvement of system performance haveSemi-reverse Paging Scheme: In this scheme [5, 48] the been the general endeavor of several proposals. But the issuescoverage area of mobile nodes is divided into several paging of reporting area identification, location-tracking delay,areas on the basis of non-increasing sequence of probability location updating and paging cost etc. have to be developedof mobile node locations. The use of advanced concept of further for better performances.location management improves the performance. But pagingdelay can be reduced further. V. BASIC OBJECTIVES OF OUR APPROACHSelective Paging: In this scheme [1, 28, 29] the coveragearea is divided into several areas based on the mobility The basic goals of our proposed scheme are as follows:pattern of the node and the inward call arrival rate to it. In a. Reducing the paging cost.order to locate any mobile node there one area is paged for b. Decreasing the wastage of network bandwidth.some fixed amount of time, instead of all the areas at a c. Lessening of location update delay and paging delay.time. If the node is found, other areas are not searched at all. d. Increasing interactivity.If not found, another area is paged. The paging cost here is e. Improvement of performance of location managementdefinitely less. But the amount of time required to locate any with the minimum possible overhead.mobile node in average practical situation here is not little.Cluster Paging Strategy: The coverage area in this scheme VI. TPRLM - TIME BASED PROBABILISTIC RELATIONAL[1, 10] is divided into concentric rings each consisting of LOCATION MANAGEMENTequal sized hexagonal cells of identical mobile nodelocation probability (for the cells within any particular ring A. Introduction

The various location management schemes as studied in The total number of cells found in an n Level linear structuresection III focus on different areas for improvement. The can be obtained from below, where n is the order of the Level.location update and paging delay, channel bandwidth wastage, ipaging cost etc. are required to be minimized for betterment. 1 + 6 Z n , Where j is the maximum LevelAgain, performance and interactivity enhancement are of i=1utmost demand. Here we present the framework of a location =1+6(1+2+3+4+5+ ....n)management scheme named TPRLM that tries to reduce the (n)(n + 1)delay for location update and paging. We have also tried to 21+6lessen network bandwidth wastage and paging cost. Thisscheme also intends to make the method dynamicallyinteractive. The overall aim of this scheme is to improve the The above stated technique reduces the paging cost and totalperformance of location management process through cost location management cost. The delay of location update andeffectiveness, network bandwidth utilization, interactivity and paging also diminishes through this approach. So, thefaster location update and paging procedure without incurring performance will improve.too much overhead.

C. The Concept ofTime BasedProbabilistic Location ManagementB. The Concept ofRelational Location Management We employ time-based probabilistic technique, detailed

In our scheme the location of a mobile node is tracked through below, for locating mobile nodes in our scheme. It can be seeninvocation of related level-based coverage area management that as the mobile station moves far away from the recentconcept. We consider the latest informed cell to be the home home location, the cost of paging increases as the mobilelocation of that mobile node. When a call arrives the tracking station moves far away from the last tracked home location. Ifbegins from the last informed visited cell (i.e. the present the number of level increases the paging costhome location). Paging initializes query for the end point increases (paging cost a n) . The call arrival probability canlocation and all coverage area cells send beacons so that the play a very important role in this context. If the call arrivalintended mobile station responds that would ultimately result time is known to the called mobile station in advance, thein an update to the location register. When the search in home mobile station can update its location just before the calllocation fails, 1st Level (i.e. the immediate neighbors of the arrival time. In this way, both costs of location update andcell) is looked for. The tracking may continue up to nth Level paging can be kept optimal. So the call arrival probability forof cells if the desired node is not found. The structures thus any mobile node may be estimated.formed can be termed as composite cells. In figure 3 below, Calculation of the Relative Call Arrival Ratewe have shown it up to 3rd level. So the home location It is fact that all mobile nodes in any area do not receive thesearches its neighbors and then those cells that share a same amount of calls. It is assumed that there are mobilecommon boundary with the neighbours, which in turn carries nodes that receive more than a hundred calls per day whileon the same procedure until the mobile station is found and the others receive around ten calls per day or even lesser than that.location is updated. The search stops when the mobile station So in order to reduce the paging cost the frequency of pagingfirst responds to the paging and identifies itself by responding the former mobile nodes would be greater than the later. Letto the nearest cell. the mobile stations be distinguished by their call arrival rates

. ;_WHome Location in the previous month. So the first step is to group the mobilestation according to their call arrival rate (say P). This may be

Ist Level Cell done by calculating the call rate of the previous month (say a

month of 30 days). Let the number of arrived call be n1 for a2nd Level Cell mobile node say ml and similarly call arrived be n2 for a

mobile node say m2. We assume that n2 is higher than nl. The3rdLevel Cell

Group No of Calls Call Arrival Rate_____________________________________________________ |permonth n Priority

Figure 3: Relational level-based coverage area division forming composite (n) 30 x 24 x (60)2factorcells

The number of paging increases as the mobile station travels Group 1 >>50000 >>0.01929 1far and wide. The number of cells in any level may be found Group II 49999-25000 0009645» 2out from the series shown below, where the leftmost element «<<0.01928represents the number of cells for home location, the second |Grouplll 24999-15000 0.009654>-»TT0.00578 3I

element from left is number of cells for 1st level and so on. Group IV 14999-5000 0.00578 »/,? «<0.001924

1+6+12+18+24+.......upto n term GroupV «.....<5000«<0.00192

Table 1 :Calculation of the call arrival rate , and setting priority respectively

inward call arrival rate (number of calls/sec) for a month for Figure 4: Movement of a mobile node in the sample model networkml is:nl / (30*24*3600) and for m2 is: n2/ (30*24*3600). It can be Here it is assumed that the mobile station receives a call atn 3*2360an ol2s 2 32430)Itcnb every cell it visits. The following diagrams shows how aeasily concluded that first one is lesser than the second one. every cell it visit ing digas shs hwaThus the mobile nodes may be distinguished into groups mobile station moves to the visiting cells The system tracks

accordng toifferet rate of inoming alls.the mobile station by the above mentioned relational locationmanagement concept. The diagrams 5 to 16 below reveal theAssigning priority to more probable call arrivalsggAino nprioority(ame r

priory factr) i givn tal fact that the number of paged cells can be reduced instead ofNow a prcority the group inwhih nthe are clsife paging all the cells. In these diagrams, different shades are

badse aondth call arrivl probabilwhity. theygroupsf ile used that denote 1 St 2nd 3rd and 4th levels consecutively.

n od whe call arrival proatisigth Thegres is oiven Figure 4 shows how the mobile station is tracked from itshiger prorityai.e.rlower pri hityfacr value(riorit factr home location to the cell where the mobile node visits. Thevalue1pmeans igest priority) fathorvae mpriore pr toba process took two Levels to track the mobile station. Aftervalue Ilmeans highest priority). Therefore more probable trackin the mobile node's visitin cell it becomes the mobilemobile node would be tracked sooner than the less probable trc1g temblno'svsmgcel tbomsheoiemobile nodes Inuable 1 ber whavnthel node's current home location. In this case, instead of pagingcalcan of cl tarleI and se o priorit toe all the cells, a small group of cells are only paged that revealscalculation Of call arrival rate (,) and setting Of priority to*r*2 the mobile node's current location which is correspondinglythem. In table 2 below, we depict the variation of time interval tedmobienode's chentloathic is orrespon gof paging based on priority using 5 different priority levels,.pae.Tempo h ewr hti hw eo hw

how the mobile station is tracked in its movements respondingto its visit in seven locations. The following figure gives

Priority factor Tracking interval emphasis and reveals the TPRLM realization a bit more_______l_________ (Sec) clearly. When the above system is realized for multiple mobile

1 0.1 nodes then the time based probabilistic model is used in2 13 10 conjunction with the current model which sets a priority for all4 100 groups.5 1000

Table 2 Division of time interval of paging in accordance to priority _______________Figure 5 Figure 6

D. Time Based Probabilistic & Relational LocationManagement.- A Model Case Study

Now we discuss the total scheme through a case study. Weconsider a region of cellular network as sample where sevenmovements of a mobile node is being attempted to track. Herethe cells in gray identify the home location. The arrows showthe movement of the mobile node in the static networks map.The movement of one mobile node in the sample map ofcellular network consisting of 148 hexagonal cells is shown _____________ ____________below in Figure 4. Figure 7 Figure 8

> (~~~~~~~~~~~~~~~~~~~~~

^ * . . . . . Z / 2Figure9 Figure 10

Figure 11 Figure 12

Figure 17: Informing cells in coverage area

Figure 13 Figure 14

/ Figure 18: Generalization of a network consisting of four composite cells

The algorithm is written assuming 5 levels. The priorityinitialization in the algorithm is done based on prioritycalculation in table 1. The time interval of paging isdetermined and implemented according to the priorities

-/ ~~~~calculated in table 2. The algorithm for each mobile node'slocation management through TPRLM is given below.

Figure 15 Figure 16Figure 5-16: A Diagrammatic Discussion of TPRLM Process TPRLM_priorityinit0

F. TPRLMAlgorithm and Illustration If (priority ==1)

1Y | 1 | Figurel8GeneraliationofaetworkcosistDelayouform0.1tesec;

Now we present the TPRLM Algorithm after specifying the E eIfpriority ==2)assumptions taken for its realization. We assume here that: Delay for 1=eca. The cells are of fixed shape. Eleif(priority ofsb. Some of the cells are special cells known as Informing deaiyfprdory1 s3e;

Cells (IC) and the rest are ordinary MSC. E eIf (priorIt se4)c. The ICs can place request to an ordinary cell sharing its Delay for 10sc

neighboring boundary for paging. Elselay==we100roiyd. No cell can be paged more than once in a single process. Else layef ori 1000=se. All ICs can only page cells of same Level in which they Delay for 1 sec;

are or one level higher than it.f. The process ends when the mobile node is found and the

location is updated. TPRLM0The ICs are positioned in balanced manner for any coveragei s t 1 alat the pot oarea as shown in figure 17. Figure 18 shows the generalization te1:Cluaehepirisofgusbsdonhenwdofanetwhborkiconsistinga four comp osite cells. The/cell/IDwin call arrival rates and initiate then coveraera wt-ICs=5

ourNscheme isnrepreened usinge bts.n Thce left mstng 3 bitseare Step:Clly TPrL pirtnt.n001se

usedforthe levelnumbers wheeasrightot5bt.r se tp3 erhfor chel numbers ineacn evlsHrwehaetherviunte :Ithemobile node foun I/base ond celhI

hoelocation ofpanyumobile noea() o ose 2

Else go to step 5.Step 5: Request the ICs of the n level to search within itself;Step 6: If found, then go to step 12.

Else go to step 7. I>Step 7: Search the cells in the common boundary of the same

level;Step 8: If found, then go to step 12

Else go to step 9.Step 9: Search the cells in the common boundary of the ICs of

(n+l)th level.Step 10: If found, go to step 12.

Else go to stepl 19.Step 1 1: If not found in the n level then the ICs will request to Figure 23: Searching the 3 level cells Figure 24: All cells are scanned

the ICs of the (n+l)th level and go to step 5;Step 12: Update Ho with the cell where the mobile node is

Found and return; Through invocation of time-based probabilistic concept and} relational level-based coverage area management, locationIn the following figures 19-24, the algorithmic process is update delay, paging cost, paging delay, network bandwidthillustrated diagrammatically for 3 level composite cell. The wastage etc. are reduced. The concept of the nth levelgrey colored cells in these figures indicate paged cells. composite cell enhances the generalization of network which

improves the scope for user-defined flexibility. The number ofinforming cells (ICs) is also optimized and yet a fair balancein location management is maintained. Our attempt to achieveinteractivity and enhanced performance is also very muchdesirable to cope with present requirement. The ICorganization, movement management etc. support us toachieve our goals.

VII. CONCLUSION

Mobility management is an extremely important issue intoday's fast-upcoming and tremendously moving world.Location management, in this perspective, is one of the mostvital affairs to be reflected upon. The fundamental concepts of

Figure 19: Searching the 1st level cells Figure 20: Searching neighboring location management and several techniques of locating anyhigher level cells mobile node are explained in the earlier sections of this paper.

Then various location management scheme proposals forwireless environment are surveyed to find out their advantagesand development scopes. We have proposed the framework ofthe scheme TPRLM that looks for better interactivity,decreased location management cost and reduced locationupdate and paging delay. It also attempts to reduce thenetwork bandwidth wastage and improve the performance oflocation management for wireless cellular networks. We areunable to produce final simulation results in this paper. Thework of simulation is presently going on. The algorithm maybe augmented further to track other critical situations that arenot covered in the present work. Analytical comparison of

Figure 21: Searching the 2nd level cells Figure 22: Searching the neighboring performance with other competent related proposals arehigher level cells another scope of future expansion of our work.

REFERENCES

[1] Demetres Kouvatos, Salam Adli Assi, Is-Haka Mkwawa, Vicente CasaresGiner, Hermann Demeer and Amine Houyou, "An Information-TheoreticApproach to Mobility Location Management: An Overview",http.://www.comp.brad.ac.uk/het-net/HET-NETsO5/ReadCameraO5/TlJO.pdf[2] Douglas E. Coiner, "Internetworking with TCP/IP", Volume 1, 1991?| orhttp://www.leapforum.org/published/internetworkMobility/split

[3] Jun-Zhao Sun, Douglas Howie and Jakko Sauvola, "Mobility management [30] A. Bar-Noy and I. Kessler, "Tracking Mobile Users in Wirelesstechniques for the next generation wireless networks", Communications Networks", IEEE Transactions on Information Theory, vol.http.//www.mediateam.oulu.fl/publications/pdf/85.pdf 39, no. 6, November 1993, pp. 1877-1886.[4] Jingyuan Zhang, "Location Management in Cellular Networks", in [31] S. Tabbane, "An Alternative Strategy for Location Tracking", IEEEHandbook ofwireless networks and mobile computing, pp. 2 7--49. John Wiley Journal onSelected Areas in Communications, vol. 13, no. 5, June 1995, pp.& Sons, Inc., 2002. 880-892.[5] Fahd A. Batayneh, "Location Management in Wireless Data Networks", [32] J. Scourias and T. Knuz, "A Dynamic Individualized Locationhttp://www.cs.wustl.edu/-jain/cse574-06/ftp/wireless_location.pdf Management Algorithm", Proc. 8th IEEE International Symposium on[6] A. Bar-Noy, I. Kessler and M. Sidi, "Mobile users: To update or not to Personal, Indoor, and Mobile Radio Communications, Helsinki, Finland,update?", Wireless Networks, 1 (1995) 175-185. September 1997, pp. 1004-1008.[7] S. Ramanathan and M. Steenstrup, "A survey of routing techniques for [33] A. Bar-Noy, I. Kessler and M. Naghshineh, "Topology-based trackingmobile communication networks", Mobile Networks and Applications, 1 strategies for personal communication networks", Mobile Networks and(1996) 89-104. Applications, 1(1996) 49-56.[8] H. Xie, S. Tabbane, and D. J. Goodman, "Dynamic Location Area [34] A. Bhattacharya and S. K. Das, "LeZi-Update: An Information-TheoreticManagement and Performance Analysis", Proceedings of 43rd IEEE Approach to Track Mobile Users in PCS Networks", MOBICOM, Seattle,Vehicular Technology Conference, Secaucus, NJ, May 1993, pp. 536-539. WA, USA, 1999, pp. 1-12.[9] C. Rose, "Minimizing the average cost of paging and registration: A timer- [35] H. Levy and Z. Naor, "Active tracking: Locating mobile users in personalbased methods", Wireless Networks, 2 (1996) 109-116. communication service networks", Wireless Networks, 5 (1999) 467-477.[10] I. F. Akyildiz and J. S. M. Ho, "Dynamic mobile user location update for [36] Charles E. Perkins and David B. Johnson, "Mobility Support in IPv6wireless PCS networks", Wireless Networks, 1 (1995) 187-196. Proc. OfMOBICOM, New York, USA, 1996.[11] Travis Keshab, "Location management in Wireless Cellular Networks", [37] A. Campbell, J. Gomez, C-Y. Wan, S. Kim, Z. Turanyi, and A. Valko,http.://www. cs.wustl.edul jain/cse574-06/ftp/cellular_location.pdf "Cellular IP", Internet Draft, draft-ietf-mobileipcellularip-00, Dec. 1999.[12] J. S. M. Ho and I. F. Akyildiz, "Mobile user location update and paging [38] Bernd Gloss and Christian Hauser, "The IP Micro Mobility Approach",under delay constraints", Wireless Networks, 1 (1995) 413-425. Proc. of the EUNICE 2000 Open European Summer School on Innovative[13] I-F. Tsai and R.-H. Jan, "The lookahead Strategy for Distance-Based Internet Applications, Enschede, 2000.Location Tracking in Wireless Cellular Networks", ACM Mobile Computing [39] C. Castellucia and L. Bellier, "Towards a unified hierarchical mobilityand Communications Review, vol. 3, no. 4, 1999, pp. 27-38. management framework", Internet Draft, draftcastellucia-uhmm-framework-[14] B. Liang and Z. J. Haas, "Predictive Distance-Based Mobility 00,June 1999.Management for PCS Networks", INFOCOM, New York City, NY, USA, [40] S. Das, A. McAuley, A. Dutta, A. Misra, K. Chakraborty and S. K. Das,March 1999. "IDMP: An Intra-Domain Mobility Management Protocol for Next[15] F. G. Nocetti, I. Stojmenovic, and J. Zhang, "Addressing and routing in Generation Wireless Networks", IEEE Wireless Magazine, October, 2002.hexagonal networks with applications for location update and connection [41] A. Misra, S. Das, A. McAuley, A. Dutta and S. K. Das, "IDMP: Anrerouting in cellular networks", from Internet. intra-domain mobility management protocol using mobile agents ", Internet[16] S. K. Sen, A. Bhattacharya, and S. K. Das, "A selective location update Draft, draft-misra-mobileip-idmp-00.txt,July. 2000.strategy for PCS users", Wireless Networks, 5 (1999) 313-326. [42] K. Daniel Wang, Ilung-Yu Wei, Ashutosh Dutta, Kenneth Young,[17] Y.-B. Lin, "Reducing Location Update Cost in a PCS Network", "Performance of IP Micro-Mobility Management Schemes Using Host BasedIEEE/ACM Transactions on Networking vol.5, no.1, February 1997, pp.25-33. Routing", Proc. Of WPMC, 2001.[18] J. G. Markoulidakis, G. L. Lyberopoulos, D. F. Tsirkas, and E. D. Sykas, [43] S. Das, A. Misra, P. Agarwal and S. K. Das, "TeleMIP:"Evaluation of location area planning scenarios in future mobile Telecommunication Enhanced Mobile IP Architecture for Fast Intra-Domaintelecommunication systems", Wireless Networks, 1 (1995) 17-25. Mobility", IEEE Personal Communications Systems Magazine, Vol. 7, No. 4,[19] W. Stallings, "Wireless Communications & Networks", Prentice Hall of pp. 50-58, August 2000.India Private Limited, New Delhi, 2003. [44] I. S. Misra, M. Chakraborty, D. Saha, A. Mukherjee, B. Deb, and B.[20] C. Perkins, "Mobile IP", IEEE Communications Magazine, pp. 84-99, Chatterjee, "A Three Level Hierarchical Mobility Management ArchitectureMay 1997. for IPv4 Networks", Proceedings of International Conference IST Mobile and[21] N. Venkataraman, "Inside Mobile IP", Dr. Dobb's Journal, Sep. 2005, Wireless Summit 2004, pp. 358-362, June 2004, Lyon, France.pp. 24-30. [45] I. S. Misra, S. Dey and D. Saha, "TLMIPv6: A Next Generation Three[22] Sourav Saha and Sarmistha Neogy, "An Analytical Survey of Mobility Layer Mobile IPv6 Mobility Management Architecture", Proc. Of WorldManagement Schemes for Wireless Networks", unpublished. Wireless Congress, San Fransisco, May, 2005.[23] B. Krishnamachari, R. Gau, S.B. Wicker and Z.J. Haas, "Optimal [46] V. Casares-Giner and J. Mataix-Oltra, "On Movement-Based Mobilitysequential paging in cellular wireless networks", Wireless Networks. 10 Tracking Strategy - An Enhanced Version", IEEE Communications Letters,(2004) 121-131. vol. 2, no. 2, February 1998, pp. 45-47.[24] H. Xie, S. Tabbane and D. J. Goodman, "Dynamic Location Area [47] H. Xie, S. Tabbane, and D. J. Goodman, "Dynamic Location AreaManagement and Performance Analysis", Proc. Of the 43rd IEEE Vehicular Management and Performance Analysis", Proc. 43rd IEEE VehicularTechnology Conference. Pp. 536-539, 1993. Technology Conference, Secaucus, NJ, May 1993, pp. 536-539.[25] Wenye Wang, Ian F. Akyildiz, Gordon L. Stuber, "Effective Paging [48] Hongmin Chen and Nallasami Mani, "An Effective Scheme forSchemes with Delay Bounds as QoS Constraints in Wireless Systems", Minimising Average Paging Costs Under Delay Bounds In PCS Networks",Wireless Networks, 2001. http://atnac2003.atcrc.com/ORALS/Chen.pdf[26] Dong-Jun Lee and Dong-Ho Cho, "On Optimum Timer Value of Areaand Timer-based Location registration Scheme" , IEEE CommunicationsLetters, Vol. 5, No. 4, April, 2001.[27] G.L.Lyberopoulos, J.G.Markoulidakis, D.V.Polymeros, D.F.Tsirkas, andE.D.Sykas, "Intelligent Paging Strategies for Third Generation MobileTelecommunication Systems", IEEE Transactions on VehicularTechnologies, vol. 44, no. 3, p. 543-553, August 1995.[28] Ian.F. Akyildiz, Joseph .S.M Ho, and Yi-Bing Lin, "Movement-basedlocation update and selective paging for PCS network", IEEE/ACMTransaction on Networking. 4 (4)(1996) pp. 629-638.[29] Vicent Casares-Giner and Pablo Garca-Escalle, "On the fractional ____________________movement-distance based scheme for PCS location management withselective paging", First International Workshop in Wireless System and This work is done in Project CRPMCS, Centre for MobileMobility in Next Generation Internet. (2004) 202-218. Computing & Communication, Jadavpur University under the

UGC Scheme "Universities with Potential for Excellence".