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.
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.
N
ext Higher Layer Entity
N
LDE -SAP
N
LME
-SAP
MCPS -SAP MLME
-
SAP
MAC Layer Entity
N
W
K
IB
N
LDE
N
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
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
Y
N
Frame from lower laye
r
Is the destination
my end-device child? Route directl
y
to
destination
Y
N
Routing capacity? Route along the tree
N
Y
Routing entry fo
r
thi s destination?
Y
Route the next hop
Dis covery routes
N
Y
Initi ate rout e
discovery
N
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
D1
A1 ZR
m
D
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
f
the destination device is ZR or ZC, this
field shall contain the actual networ
k
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-
b
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
S
A
B
D
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
S
A
B
D
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
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