Coexistent heterogeneous wireless networks may interfere with each other and result in significant performance degradation when devices are collocated in the same environment. With the increasingly deployed Wireless Personal Area Network (WPAN) and Wireless Local Area Network (WLAN) devices, channel conflict has become very frequent and severe when one WPAN technology coexists with other WLAN technologies in the same interfering range. In this paper, we study the coexistence issue between IEEE 802.15.4 and IEEE 802.11b. We present analytical models on the non-conflicting channel allocation probabilities, focusing on the coexistence scenarios of IEEE 802.15.4 coexisting with IEEE 802.11b. The interference model of IEEE 802.15.4 wireless Personal area network (WPAN) affected by IEEE 802.11b wireless Local area network (WPAN) also presented. The packet error rate (PER) of the IEEE 802.15.4 under the interference of the IEEE 802.11b is analyzed, and is obtained by the bit error rate (BER) and the collision time. The BER is obtained from signal to noise and interference ratio. The safe distance ratio can be obtained from the PER. The analytic results are validated for various topologies using Qualnet 4.5 simulation. Further this paper investigates the PER of IEEE 802.15.4, with the consideration of the mobility models of the WLAN nodes.

Wireless Sensor Network (WSN) consists of low cost tiny sensor nodes with limited energy resource, so it is a tedious task to develop energy efficient routing schemes that enhances the network lifetime. In WSN, clustering is used to improve the efficiency of finite energy resource. LEACH protocol is one of the widely used clustering techniques in WSN. So, in this paper, an energy efficient LEACH protocol is designed with network coding for WSN. Initially, the clusters are formed with the LEACH protocol, where it uses the residual energy metric and drain rate to select the cluster heads.  Since network coding is an optimal technique to enhance the network performance by minimizing the number of transmissions, it is incorporated into the LEACH Protocol, where it has been applied at the cluster head levels. Furthermore, the next level of network coding is processed at a node by selecting any of the nodes as a master node. The simulation results show that the proposed scheme performs better than the EE-LEACH and LEACH protocol in terms of network lifetime, packet delivery ratio.

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