The ZigBee specification is a standard for low-power consuming wireless devices. The ZigBee protocol stack has a layered structure containing four distinct layers of which the two lowest layers are defined by the IEEE 802.15.4 standard. Building on this base the ZigBee standard defines a network layer and an application layer. Especially in science and education it is of use to implement each layer independent of the other layers. This makes it possible to compare different implementations and to use software from different manufactures. The network layer of the standard defines an on-demand routing protocol similar to the AODV routing protocol. Initiating route discovery in an on-demand protocol is important in order to keep routes up to date but it may not be done to often because of power consumption. This thesis describes the work of implementing a subset of the network layer in a strict layered approach and evaluates route discovery initiation. It is found that the hardware used in this work makes it not preferable to implement a strict layered network layer, because of timer issues. Having compromissed the strict layered approach, measurements performed in non-beaconing networks indicates a throughput of about 50Kbits/s. However, if no packet loss is tolerated the throughput is more like 40Kbits/s. In the evaluation of route discovery initiation it is found that the number of times route discovery is initiated can be slightly reduced by making use of the link quality indicator for the link between a parent and a router-capable child.
Author: Armholt, Magnus
Source: Lulea University of Technology
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