International Journal of Computer Applications (0975 – 8887) Volume 92 – No.3, April 2014 40 Deviation of Mobile Nodes in Beacon Enable Zigbee Sensor Network Amritpal Kaur M-Tech Scholar Deptt. of ECE SBSSTC, Ferozepur, Punjab, India Jaswinder Kaur Asst. Prof. Deptt. of ECE SBSSTC, Ferozepur, Punjab, India Gurjeevan Singh DIC-ECE Deptt. of ECE SBSSTC(Polywing), Ferozepur, Punjab, India ABSTRACT This research work is based on IEEE 802.15.4/ Zigbee wireless sensor network. The main aim of this research is to analyze the performance of Zigbee network topologies in beacon enable mode by giving the random waypoint mobility model to its nodes. The scenarios have investigated the performance of network by varying speed and mobility of nodes. Results are evaluated using parameters throughput, data traffic sent and data traffic received and number of hops. The simulation is done by OPNET modeler 14.5. The results conclude that tree topology give good performance in case of data traffic sent and data traffic received, the throughput is also efficient. Hence tree topology constructs a robust network using mobile nodes. Keywords WSN, Zigbee, CSMA/CA, Mobility, Topologies. 1. INTRODUCTION There are many numbers of small sensors spread everywhere in a wireless sensor network either inside or very close to the event to be sensed. Sensor nodes consist of sensing, data processing, and communicating components. Different wireless technologies like IEEE 802.11 WLANs, WPANs, and Bluetooth etc. can be used as Wireless sensor networks. Now these days the requirement of applications are low- power having a range of about 30 to 200 feet with data rates around 300 kbps. IEEE 802.15.4 is the approved low-rate standard for a simple, short range wireless communication with long battery life up to a single year. The low rate (LR) wireless personal access network (WPAN) (IEEE 802.15.4/LRWPAN) has to be implemented in industrial, residential, and medical applications with very low power , low cost, and low data rate and QoS. The low data rate to consume little power in the LR-WPAN [1]. ZigBee is a network and application layer specification developed by a multi-vendor consortium called the ZigBee Alliance. The IEEE 802.15.4 standard provides the physical (PHY) layer and medium access control (MAC) sublayer specifications for low data rate wireless connectivity [2]. The PHY layer performs functions like in-channel power energy detection, link quality indication, channel selection, Clear Channel Assessment (CCA), and also the transmission and reception of packet through the radio channel. The standard defines three bands: 868 - 868.6 MHz, 902 - 928 MHz, and 2400 - 2483.5 MHz, in which 26 separate channels are available with the bandwidth of 3 MHz. The MAC layer is responsible for channel assessment. Two different types of operating schemes are available in Mac layer for channel assessment. The first one is beacon mode based on CSMA/CA with time- slot allocation to schedules the network access. The second is non-beacon mode, which based on a pure CSMA/CA protocol. In non-beacon mode, each station wishing to transmit data after sensing the channel for desired time duration [3] In beacon-enabled mode a superframe structure constructed based on the Beacon Interval (BI) and define by the network coordinator, where BI defines the time between two consecutive beacon frames and on the Superframe Duration (SD), basically the active portion of the BI, and transmission of frames has been done by dividing BI into 16 equally-sized time. If BI > SD an inactive period is defined. During the inactive period all nodes save energy by moving in sleeping mode. There are many ZigBee applications for home-appliance networks, healthcare, medical monitoring, consumer electronics, and environmental sensors. Mobility is the necessary requirement of wireless networks in many applications that also impose QoS requirements. A mobile node has to listen to neighbor attachment points periodically so that it updates its neighbor list. IEEE 802.15.4/ZigBee nodes usually have less energy capacity, thus mobility management approach has to ensure low energy [4]. A network with highly mobile users raises challenging mobility issues, as the ZigBee specification defines a device discovery procedure activate by central server which is difficult to find out certain mobile end device. For this purpose, the central server simply over supplies the message in the whole network to find out the displaced end device. Due to the geographical structure of the network the mobility patterns of sensor nodes are inherently regular in many applications. To construct a proper routing topology the regularity should be developed which provides useful information for sensing data deliveries [5]. Doubtlessly mobility is a part of the ZigBee vision, and it is significant for the proper functioning of many visualized ZigBee applications. Since mobility is estimated and obligatory. A tolerable mobility support is necessary to make certain connections between mobile devices which are omnipresent [6]. In this paper, the behavior of Zigbee topologies has been investigated by giving mobility to nodes and also analyzed the performance of network, if it is totally mobile. 2. SYSTEM MODEL The IEEE 802.15.4 can operate either in a Beacon enabled or a non-Beacon enabled mode. The coordinator sends periodic Beacons in a Beacon enabled network, which allows the network nodes to make synchronization with each other and nodes communicate with a superframe structure. The non Beacon enabled mode is often used for light traffic between the network nodes. The MAC control and Beacon frames uses a slotted CSMA/CA mechanism to access the channel. Data frame that follows the acknowledgment of a data request command but acknowledge frame doesn’t follow the slotted CSMA/CA mechanism [7, 8]. An IEEE 802.15.4 WSN is consist of a parent PAN coordinator and a set of children and parent nodes. There are two types of devices used in this