Implementation of ZigBee Network Layer Based on AODVjr and Tree Hirarchical Route Algorisms

doi:10.4236/jsea.2011.48056

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Journal of Software Engineering and Applications, 2011, 4, 487-490

doi:10.4236/jsea.2011.48056 Published Online August 2011 (http://www.SciRP.org/journal/jsea)

487

Implementation of ZigBee Network Layer Based

on AODVjr and Tree Hirarchical Route Algorisms

Qiyong Pan1, Jin Wu2, Yihuai Wang2, Jingfei Ni2

1College of Physics & Electronic Engineering, Changshu Institute of Technology, Changshu, China; 2College of Computer Science

& Technology, Soochow University, Suzhou, China.

Email: [email protected]

Received June 20th, 2011, revised July 22nd, 2011, accepted July 30th, 2011.

ABSTRACT

The basic functions and the relative concepts of ZigBee network are analyzed in this paper. The implementation method

of ZigBee network layer is proposed, it includes how to build a new network, add a node to th e network, send data and

receive data. The distributing address assigning mechanism, the tree hierarchical route algorism and AODVjr algorism

are implemented. Finally, the ZigBee network layer protocol is tested.

Keywords: ZigBee Network, AODVjr, Route Choosing, Route Finding

1. Introduction

ZigBee [1] network layer is between MAC layer and ap-

plication layer. It can provide the suitable service inter-

face for the application layer. The basic functions and the

relative concepts are generalized in this paper. The proc-

ess of network building is proposed in this paper. The

AODVjr route algorism is introduced.

2. ZigBee Network Layer

In the ZigBee network, due to the energy limit, the nodes

can not be communicated directly, usually needing the

intermediate nodes to transfer the data to the destination

nodes by the multi-hop method.

ZigBee network layer is responsible for the route

finding and the maintenance, and it includes two func-

tions such as route choosing and data transferring. Route

choosing is finding the optimum path from the source

node to the destination node. Data transferring is trans-

ferring data along the optimized path.

The reference model of ZigBee network layer is

showed as Figure 1, where MCPS-SAP is the data ser-

vice interface for MAC layer providing to network layer.

MLME-SAP is the management service interface of

MAC layer providing to network layer.

NLDE-SAP (Network Layer Management Entity-

Service Access Point) is the data service interface of net-

work layer providing for the application layer. NLDE-

SAP assembles the data provided by application layer to

network layer protocol data unit (Network layer Protocol

Data Unit, NPDU), and transfer it to the destination node

of the network layer. At the same time, NLDE-SAP can

unpack the received NPDU and transfer the unpacked

data to the application layer. Therefore, NLDE-SAP can

achieve data transferring between two equal application

layers.

The network layers mainly do the following works:

NLDE have the ability of generating NPDU, route

choosing according to the specific network topology

structure and executing some safe operation. NLME have

the ability to configure protocol stack according the op-

erations need, build a new network, add or leave a net-

work, configure the address for the device of the network

and execute neighbor finding and route finding.

ext Higher Layer Entity

LDE -SAP

LME

-SAP

MCPS -SAP MLME

SAP

MAC Layer Entity

LDE

LME

Figure 1. ZigBee network layer reference model.

Implementation of ZigBee Network Layer Based on AODVjr and Tree Hirarchical Route Algorisms

488

ZigBee network layer supports star, tree and mesh

topological structure. The mesh network is used in this

paper.

3. ZigBee Network Route Protocol

The protocols of ZigBee has several different types [2,3]

includes DSR [4], AODV [5] and AODVjr [6]. AODVjr

(AODV junior) [7,8] is the simplified version of AODV.

AODVjr removes the sequence numbers and hop count,

only permitting destination node replying to the first ar-

rived route request. The HELLO messages, Route Error

and precursor lists in AODV are not considered in

AODVjr. AODVjr make s rou te f indin g more efficien t [9-

11].

AODVjr has the same ability with AODV, but

AODVjr is relative simple, easy to be understood and

implemented. In the process of route maintenance, the

spending of control package of AODVjr is less than

AODV. Therefore, AODVjr and tree layer algorism are

combined in the process of route protocol implementa-

tion of protocol stack.

4. Implementation of Network Layer

Function

4.1. Building Network

ZigBee network can just be implemented by the device

having cooperative ability. The device is initialized to a

ZigBee coordinator (ZC) after building the network. The

ZigBee network just has one ZC. The building flow for

the ZigBee network is sh owed as Figure 2.

The top layer set the process of the new network by

using primitive language NLME-NETWORK-FOR-

MATION request.

After the setting is finished, NLME firstly execute the

energy check scan to choose the acceptable channel, and

then execute the active scan in the acceptable channel to

choose the channel to build the new network on it. Then

NLME choose a PANID less than 0x3fff for the new

network, set the own 16 bit network address as 0x0000

and execute the checking and initializing the attribute

nwkExtendedPANID value. Finally, NLME uses the

primitive language MLME-START request of the MAC

layer to start PAN, announce to top layer and build the

network state.

4.2. Adding Nodes to Network

When a device in the network admits a new device add-

ing to the network, the new adding node is the son device.

The first device is parent device. A son device can be

added to the network by the following ways: throug h the

MAC layer association process or t he pre-appoi nt ed parent

device, it can be added to the network directly. Moreover ,

NLME-NETWORK-

FORMATION.confirm

MLME-SET.confirm

MLME-SCAN.request

MLME-START.request

MLME-START.confirm

MLME-SCAN.request

MLME-SCAN.confirm

NLME-NETWORK-

FORMATION.request

ZigBee Coord.APLZigBee Coord.NWK ZigBee Coord.MAC

MLME-SET.request

Select channel,PAN ID

and logic address

detection scan

Perorm energy

detection scan

Figure 2. Establishing a new netw or k.

isolated point device can be added or read to the network

by isolated point manner.

4.3. Sending or Receiving Data of Network Layer

The Network layer transfer NPDU to the data service

entity of MAC layer, and request MAC layer sends

NPDU. MAC layer returns the data sending result to

network layer.

The process of network layer receiving data is as fol-

lows: after the data frame received from MAC layer, the

network layer does validity check and examines whether

the destination address of the frame is accord with the

network address of the device. If the address matched,

then the frame will be send to the top layer to be man-

aged, otherwise, if the address is not matched and the

device has no rou te ability, the device ne twork will query

the route table to choose the suitable next hop to do the

data transfer.

5. Implementation of Route Function of

Network Layer

5.1. Basic Route Algorism of ZigBee

When the device network layer receive a single broadcast

data frame from MAC layer or the top layer, the frame is

routed according to the route algorism showed in Figure

3. The device having route ability should find the route

record of the destination address of the frame, forward

the frame and set the route finding process when there is

no route records. For the device having no route ability,

Implementation of ZigBee Network Layer Based on AODVjr and Tree Hirarchical Route Algorisms489

Is i t for m e? Send frame to

higher layer

Frame from lower laye

Is the destination

my end-device child? Route directl

destination

Routing capacity? Route along the tree

Routing entry fo

thi s destination?

Route the next hop

Dis covery routes

Initi ate rout e

discovery

Figure 3. The basic route algorism of ZigBee.

if the NIB attribute nwkUse-TreeRouting is equal to

TRUR, the device will forward the frame along with tree

by using the hierarchical route.

5.2. The Tree Hierarchical Route Algorism

In the tree hierarchical route algorism, if the destination

device of the frame is offspring of the current device,

then it is forwarded to the offspring device, otherwise, it

is forwarded to the parent device. So the offspring device

and the hierarchical route algorism can be assured as

follows:

In the ZigBee network every device is the offspring

device of ZC, but for any ZED it has no offspring device.

For the device ZR with the address A and the depth d, if

the following logic express is established, then the desti-

nation device is the offspring device of ZR showed in

Equation (1).



1ADACskipd 



(1)

When the destination device of the frame is the off-

spring of the current receiving device, then the address N

of the next hop is as the Equation (2):











  

ZEDwhenD

A1 ZR

Thesun device isARCskipd

NACskipdsundevice is

Cskip d

 







 









，

(2)

5.3. Route Table Structure

ZR and ZC maintain a route table to record and maintain

the route information to reach some destination devices,

the format of stored information is showed as Table 1.

ZR and ZC may obligate some route table item to use it

in route modifying an d route ability running out.

5.4. Route Finding Process of AODVjr

Route finding is the pr ocess of d evices cooperating in the

network, finding and building the route. Routing finding

is always executed aiming at the specific source device

and the destination device .

AODVjr algorism is interest-driven and the route is

selected by source node. Considering the factors such as

saving energy, cost and application convenience, AODVjr

simplifies the features of AODV protocol, just using

RREQ (Route Request,) and route reply command

(Route Reply, RREP). It threw off sequence number of

AODV, immediate node reply, the seasonal HELLO in-

formation packet, route mistake command (Route Error,

RERR) and usher list [5,10], still keep the main func-

tion of AODV. In AODVjr due to exist no sequence

number, after the destination node is permitted then

RREP command can be replied. Therefore, the route cy-

cle problem can be avoided. The inefficient information

packet can emerge improving the communication effi-

ciency. The route finding process of AODVjr is showed

in Figure 4 and Figure 5.

Table 1. Route table item format.

Field name Size Description

Destination

address 2 bytes

16-bit network address or group ID. I

the destination device is ZR or ZC, this

field shall contain the actual networ

layer address; if the destination device is

a ZED, this field shall contain the net-

work address of that device’s parent

status 3 bitsThe status of the route

Many to one 1 bit A flag indicating that the destination is a

concentrator that issued a many to one

route request

Route records

required 1 bit A flag indicating that the a route record

command frame should be sent to the

destination prior to the next da t a p a cket

Group ID flag 1 bit A flag indicating that the destination

address is a Group ID

Next hop address 2 bytesThe 16-

it network address of next hop

on the way to the destination

Implementation of ZigBee Network Layer Based on AODVjr and Tree Hirarchical Route Algorisms

490

Sou rce node

Destination node

6. The Test for the Network Layer

The test of network layer is similar to the MAC layer.

The content of data frame received from the network

layer is justified correct or not. Th e record s in rou te table

and the route finding table is justified correct or not in

the route finding process. For only the route request

command and route reply command is realized in proto-

col stack, so the content can be checked by using sequen-

tial port according to some form.

Figure 4. Source node S broadcasting RREQ. 7. Conclusions

Source node

Destina ti on node

The reference model and the basic function are general-

ized. The network frame type and the format definition

are given. The network building, adding node, data

sending and receiving are realized. The common route

protocol is summarized in wireless communication. The

tree hierarchical route algorism is expounded in route

table structure and distributing address assigning mecha-

nism. The network layer is tested finally.

Figure 5. Destination node D single broadcasting RREP. REFERENCES

[1] ZigBee Alliance, “ZigBee Specification,” 053474r17, 17

January 2008.

When the source node S sending data to the destina-

tion node D, if the route connecting to the destination

node D is not found, the RREQ command frame is

broadcasted by network layer, and ask neighbor node to

find the path to the destination node. Every node receiv-

ing RREQ command frame maintains route information

to the source node, and help source node S broadcast

RREQ command frame. RREQ command frame will be

forwarded to the destination node D. When the destina-

tion node D received the RREQ command frame, ac-

cording to the route cost of RREQ to decide whether

renew the route table, choose the minimum cost path to

the source node S and r eply RREQ command frame. The

protocol stack using the arrival time of RREQ command

frame as the route cost, the first reached cost path is se-

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The process of source node finding the destination

node is through the broadcast RREQ. In the process the

reverse route is built from the destination node to the

source node, and the reply RREP is single broadcasted

from destination node to source node. Then the positive

route is built between source node and destination node.

After the positive route is built, the sour ce node can send

the data to the destination node.

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[8] X.-Q. Zheng, “Wireless Ad Hoc Technical and Practical

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In the route maintenance, the positive route can be

maintained from source node. If the destination node does

not need to send data to source data, it can send a con-

necting information packet to the source node to main-

tain reverse route. If the source node has not received

data from the destination node at an interval, it is thought

the path is invalid and the route finding can be renewed.

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