2009 IEEE International Advance Computing Conference (IACC 2009)Patiala, India, 6-7 March 2009

Address Borrowing In Wireless Personal AreaNetwork

2Debabrato Giri' Uttam Kumar RoyDept. of Information Technology Dept. of Information Technology

Jadavpur University, Salt Lake Campus Jadavpur University, Salt Lake CampusBlock-LB, Plot-8, sector-Ill, Block-LB, Plot-8, sector-Ill,

Kolkata-700098, India Kolkata-700098, Indiadebabrato.giriktcs.com' u_roy(itjusl.ac.in

Abstract-IEEE 802.15.4-2003 is a standard for Low rate, Low node being the only node that has no other node above it in thepowered, Low memory wireless personal area network hierarchy - the hierarchy of the tree is symmetrical[2], each(WPAN).The Physical layer (PHY) and Medium access control node in the network having a specific fixed number, f, of(MAC) specification has been given by IEEE [12, l1]and the nodes connected to it at the next lower level in the hierarchy,Network layer by ZigBee Alliance[17]. They support two kind of the number, f, being referred to as the 'branching factor' of thenet work Tree/Mess. In tree network no routing table is required hierarchical tree.for routing. After the great success in PAN this technique hasalso been tried to apply in business Network too. The mainproblem with this routing is that the maximum length of the network is 16 hops and in some cases the network can not growbecause of the exhaustion of address in some part while the otherpart is very poorly loaded. Here In this paper we have provideda unified address borrowing scheme which can be easily appliedto grow the network beyond 16 hops and overcome the address------_exhaustion problem by borrowing address.

Index Terms-PAN;WPAN;Tree; Mesh; Address Borrowing;Routing

Figure 1: Tree NetworkI. INTRODUCTION

Wireless Personal Area Networks (WPANs) are used toconvey information over relatively short distances. Unlike A. Distrubuted address assignmentwireless local area networks (WLANs), connections effected gvia WPANs involve little or no infrastructure. This feature Given values for the maximum number of children a parentallows small, short-range operation, reliable data transfer, and may have, nwkMaxChildren (Cm), the maximum depth in thea reasonable battery life, power-efficient, inexpensive network, nwkMaxDepth (Lm), and the maximum number ofsolutions to be implemented for a wide range of devices. routers a parent may have as children, nwkMaxRouters (Rm),

then CGkip(d), essentially the size of the address sub-block beingTwo topologies are used in this kind of network Tree and distributed by each parent at that depth to its router-capable

Mesh. The beauty of tree address allocation is that it does not child devices for a given network depth, d, is:require any routing table to forward a message. It uses a simplemathematical equation for address assignment and routing.

1+ Cm.(Lm-d-1), IjRm = 1II. OVERVIEW OF TREE ROUTING Lm -d-I

There are different kinds of routing, Distance vector Routing C (d+)= Rm mm,Ri[1, 10, 16], Compact Routing etc. but tree routing is simplest sk-p 1 Ramong them as it does not require any Routing table. The typeof network topology in which a central 'root' node (the toplevel of the hierarchy) is connected to one or more other nodesthat are one level lower in the hierarchy (i.e., the second level)with a point-to-point link between each of the second level Network addresses to the end devices are assigned using thenodes and the top level central 'root' node, while each of the following equation [17].second level nodes that are connected to the top level central'root' node will also have one or more other nodes that are one An= Parent - Cskjp(D).Rm Hlevel lower in the hierarchy (i.e., the third level) connected toit, also with a point-to-point link, the top level central 'root' 1 n Cm - Rm And Apar.ent is address of parent

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B. Networkformation III. PROPOSED ADDRESS BORROWING SCHEME

Let Cm=2, Lm=4, Rm=2 In this scheme a node will be allowed to join a network at anode even if it has exhausted its available address byborrowing a address from a different node which is having free

[Depth in the Network | OffestValue [Cskip(d)] address and assigning it to the requesting node i.e. the new0 15 node will physically be attached to some node and will have1 7 the physical address of some other node with addition of very

2 3small routing table.

F3 1 In the following Figure 3 Node 25 is physically attached tonode 28 but the address '25' has been borrowed from node 24.

4 0 The dotted line indicates that relation ship.

A. Design consideration.1. PAN devices are very low powered device i.e. they

require very lesser amount ofpower to drive2. PAN devices have very lesser amount of memory

typically several Bytes to a few KB.

I SW16 | B. RequiredData StructureProbable address available table: This table will be

maintained at the PAN coordinator i.e. Node 0 in Figure 3. It17X 3 1 will have 3 colunm Router address, Child Router free and

Child end device free.

Figure 2: Address Allocation 23

C. Advantage 2

Simplicity-It's a very simple network no complex path isformed. A device only communicates with its Parent and 28Childs.

Scalability - The tree network can grow more than that ofmesh networks.

D. DisadvantageThe address is 16 bit so the maximum length of the network Figure 3: Address Borrowing

is 16, and available address at a node can not be used in othernodes.

Now in Figure 2 the Cskip (d) for node 28 and 29 is 0 that is Router Address Child Router Child endno address is available at these nodes, so if any node wants to free device freejoin the network at either of these two nodes will fail even 1 P Fthough free address is available at other node. The proposed 17 B Balgorithm discussed next section suggests a way to overcome 27FFthis. 24 |T Fl

1182 2009 IEEE Internlationlal Advance Computing Conference (IACC 2009)

Router address is the address of the Node where free address replyGetFreeAdd:might be available. Description- This message will be sent to inform the

Child Router address free and child end device free colunm available address.will indicate the availability of the address it can have 4 values Sender - PAN Coordinator.E=Empty P=Partially Full and F=Full T= Threshold Reached. Receiver- Address requesting node.

Initially these two columns will be marked as E for all the Parameters: Free Address, Donor Address, Address rangeRouters, and will be updated by the PAN coordinator as (Cskip(d)) in case of router address.Network grows using the algorithm discussed later.

deallocateVisitingAddress:Visiting child table: This table will be maintained at the Node Description- This will be send when the visiting nodewhich has borrowed the address from other node i.e. Node 28 wnsctionn from the network.in Figure 3. For most of the node this table will be empty. Sendet Parentof the node.

Sender - Parent of the visiting node.Actual Address Parent Address Receiver- Address donor whose address has been fetched

25 24 from visiting child table.Parameters: Actual address.

This table will be storing the actual address of the visitingnode. emptyChild:Tunnel table: This table will be maintained at the node which Description- This message will be send when any nodehas given the address i.e. Node 24 in Figure 3. This table will become empty i.e. have no child.be used to tunnel the packet to the intended receiver. This table Sender Any node.will have two columns one for Actual address and the other for Receiver- PAN coordinator.tunnel address. Parameters: End device free/router free

Actual Address Tunnel Address25 28 addressFull:Description- This message will be send when a node has

This table will be empty for most of the nodes. exhausted all its available address.Sender - Any node which has exhausted its address.

C. Messages and their Descriptions Rcie-PNcodntrReceiver- PAN coordinator.Following messages will be used in order to borrow a free Parameters: Router/end device address full

address from any node. The address can be a single end deviceaddress or a full address block (router address).

getFreeAdd: D. Method descriptionsDescription-This message will be send to get free address. hasFreeAdd: This method will be invoked by any node afterSender - Any node which has exhausted its address. receiving joinNetwork message from a node. If the node hasReceiver- PAN coordinator. exhausted its available address it will send getFreeAddParameters: Router/End device address required. message to the PAN coordinator.

hasFreeAdd: choseProbableNode: This method will be invoked by theDescription- It will be sent to query the availability of free PAN coordinator after receiving getFreeAddress messageaddress at any node. from any node. It will look in the Probable AddressSender - PAN coordinator. Available Table (PAAT)§ and select a probable node whichReceiver- Any node selected by Pan Coordinator using can donate address based on the following logic [Figure 4].Chose Probable node algorithm. In Figure 3 the address is available at node 1, 17 and 24 as

ParameteProbableRouter/Ende device addressrequithe node 24 is closest to node 24 the algorithm will select it forParameters: Router/End device address required. the 1st time.

replyHasFreeAdd: If some node say node 29 wants to send a message to nodeDescription-It will be send in reply to hasFreeAdd. 25 the message will traverse in the following way.Sender - Any node which has received hasFreeAdd.Receiver- PAN coordinator. 29427-23-24(Tunnel the packet to 28)423-27-28Parameters: No of available address, donated address, (Route to visiting child) -25Address range (Cskip (d)) in case of router address

§ Here the algorithm will look for the nearest node to theaddress requesting node so that message transmissionoverhead due to tunneling can be minimized.

2009 IEEE Internlationlal Advance Computing Conference (IACC 2009) :183

Look for a nearest node rer)lvHasFreeAddress/addressFull messaqewith status E (Empty)

Check the no of available address (Routeraddress,Child adderss)

/ Foundi NO;Lok__raeaes_nd\? / -| with status P (Partially full)eshold reached?

/Found\ NO node w statu t Update Child Router free/Child enddevice free_ < v >~~~P node with status TYE; \ : / |(Threshold reached) column of ProbableAddressAvailableTable to

| * I ~~~~~~~~~~~'T'(Threshold reached ) for address donor node

YES / Founid | |Update Child Router free/Child end devicer 4 P?N NO Pfree column of ProbableAddressAvailableTable

to 'P'( partially filed ) for address donor nodeThis Send HasFresAddfo hg plygetFree cnetr i.wtheselected node Addcommunicat with each other but if the devices areless the adUpdate Child Router free/Child end device

free column of *JFigure 4: Probable Node Selection a ProbableAddressAvailableTable to 'F'( Full ) for

Figure 5: Probable Address TableThis scheme will be use full for highly communicating Update

network i.e. where every participating node used to UpaeVstn. abe.hsmto.wl eivkdbcommunicate with each other but if the devices are less th adrs reusig nd.fe eevncommunicating i.e. they rarely send messages but require a reyGteAdesmsagfomPNCrinorofast response when they want to join the net work then a slidpate th Viitn chl tal tinethevsigciladvariation of the algorithm can be used where PAN coordinator update the Visiting child table toinsert the visitig child and

will chose the node which is closest to itself and thus minimaldelay will be incurred. So in that case PAN coordinator will E. Message Passing Overhead Calculationselect Node 1 as the probable node. Two message are required to join a network by any node

one for join request and the other for acceptance. FourUpdateTunnelTable: This method will insert a new row additional messages are required for borrowing address from

in the Tunnel table containing the address of the node to other nodewhich it is donating the address and the address itself. This let M= No of Node, X% is the percentage of addressinformation will be used to tunnel the packet to the actual borrowing required to form the net work average Distancerecipient. (No of hops) between PAN coordinator and address Borrower

be P, Between PAN Coordinator and Donor be Q and DonorUpdate ProbableAddressAvailableTable: This method and Borrower be R, the depth of the network be S, Total no of

will be invoked by the Pan coordinator to update message sent is T, and U%0 be the percentage of tunnelProbableAddressAvailableTable after receiving message. Figure 6 presents the address borrowing messagereplyHasFreeAddress message from address donor node or sequence, Figure 7 present packet routing sequence andaddressFull message from any node to reflect its updated Figure 8 represents Leaving the Networkmessage sequence.knowledge about the free address available node.

1184 2009 IEEE Internlationlal Advance Computing Conference (IACC 2009)

n : Now let's see the performance of the algorithm for_wed oed P ionddifferent network configuration. As address borrowing will

I I only take place when a node has exhausted its availableI I address, the percentage of borrowing will be lower, the no of

IjoinTheNetworkl hasFree tunneled message will also be very less compared to the total

[Al con nectAdd nno of message sent over the network as the 1st message from a

getFreeAdd choseProbable sender to a visiting node only require tunneling the subsequent

:h;asFreeAdd message will be send directly to the visiting node.

replyGetFreeAdd rep 4yHI-asFreeAdd IYe 1uate

joinNetwork Vis itin gTab e updateProbableAddress-AvailableTable

Figure 6: Address Borrowing Sequence W hout |crrc½n

:Sendemode IntermediateNode :Addressdonor :BindingParent VisitingNode

sendMessage i ± DetermineNextHop f

p[A]connect unowg|SPack

Tunnel ffor-ward i Figure9:Total No of message for Network Creation GraphFigure 7: PacketRoutig S eprocess

replyGet IILtOetermineW Borro*nFreeAdd NexHop

OinNetwork w Visiting

Fiegure 7:Fiacketegoutsngsequence || N Creat

'Visibnqnoe 'AddBorrwerN ode TAddes Dno

I . I I . I I . 1 11 1 1 ....................I 11~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~0

I I301N D ~ _ *| 1

leaveNire 8work S a(WOB) i 1 2 4 5 6 7lil lw~~~~iswnchildonlll1- -- NolfreeAddressj ll

Agceptf n upcdrti Figurel0:_Average_No_of_message_for_NetworkCreationA m AddressFreed2 F 1a

'IIupdatebVisitingTaS+ *

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Figure 8: LeaveNetworkSequence 11...........

Total message (TM) for network creation without borrowing 1 G_I 1

The Average distance (AV) traversed per data message11 _I1

(WOB) is S.11 1o-I 1fl ~~~~~~1.2 3 4 5 6 7 1Total messagye for network creation with borrowing(WB) I XiL

Total message Average no of Average distance REFERENCESParameters for network message to join traversed by

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186 2009 IEEE Internxational Advance Computing Conference (IACC 2009)}