Coexistence of Zigbee and Wi-Fi Using White Space Aware HMM Protocol

In this information age, there are two trends that have reflective impact on our lives (i) we depend more and more on information technologies, (ii) and our mobility is getting higher and higher. The demand on wireless handheld devices just keeps on increasing. One particular type is gaining wide-spread acceptanceshort range wireless technology, due to its low cost. They are WLAN and WPAN. Nowadays, wireless technologies have been incorporated into various communication and networking applications embedded in many military, industrial and civilian products. WPANs focus on the space around a person or object that typically extends up to 10 meter in all directions. The aims of WPANs are low-cost, low power, short range and very small size. The IEEE 802.15 working group was formed to create WPAN standards, which has currently defined three classes of WPANs that are differentiated by data rate, battery drain and quality of service (QoS) capabilities [1] 1) High data rate WPANs (IEEE 802.15.3) that require very high speed and strong QoS support, and are normally used for multimedia applications, 2) Medium data rate WPANs (IEEE 802.15.1/Bluetooth) that handle a number of various tasks such as cell phones and PDA communications (among themselves or with peripherals, e. g. earphones, printers) and provide QoS suitable for voice communications, 3) Low data rate WPAN (IEEE 802.15.4/LRWPAN) that are intended for a set of industrial, residential and medical applications with requirements of very low power consumption and cost and relaxed needs for data rate and QoS. Wireless Sensor Networks discussed in this paper belong to the third class of WPAN. This paper aims at solving the problem occurring due to the coexistence of Zigbee and wifi in the same environment. The high power wifi signals end to override the Zigbee signals and thus deterioting the Zigbee data. This problem has been addressed using white space available in the wifi spectrum and accommodating the small Zigbee packets in this white space using the hidden markov model system.