Having seamless Internet connection is highly desirable for wireless sensor network (WSN). IPv6 offers the most promising solution to deal with the large quantity of nodes or "things". This demonstration presents a versatile research and development (R&D) or prototyping platform, on which we implement generic hardware and software framework for sensing/monitoring as well as remote control applications.

The low-power, low-rate ZigBee wireless sensor networks are vulnerable to the interference of collocated Wi-Fi wireless local area networks (WLAN). The results acquired through our extensive experimental studies on ZigBee-WLAN coexistence indicate that ZigBee connections may experience severe packet losses, caused by combined effect of interference and relatively long receive to transmit (RX-TX) turnaround time in ZigBee devices, even when the Wi-Fi and ZigBee devices are able to detect each other's signal and apply CSMA/CA algorithm accordingly. This paper proposes a novel Adaptive Preamble Padding with Retransmission Control (APPRC) technique for ZigBee devices to address this issue, meet certain packet loss rate (PLR) requirement, and improve packet transmission efficiency when they are suffering time varying interference from the collocated WLAN. The experimental performance evaluation results showed that the proposed APPRC technique can achieve significantly higher transmission efficiency while satisfying PLR requirements of sensing applications than packet retransmission. The technique described in this paper is patent pending.

Recent studies have shown that the low-power ZigBee based wireless sensor networks (WSN) are vulnerable to the interference generated by nodes of Wi-Fi wireless local area networks (WLAN). Mutual interference can be mitigated at nodes of either technology when energy detection (ED) is enabled in clear channel assessment (CCA). From our experimental studies on ZigBee and Wi-Fi coexistence issue, it is determined that a significant amount of ZigBee packet losses occur due to the Wi-Fi interference induced corruption of the physical layer header of ZigBee packets, which could happen even when the ED mechanisms of the Wi-Fi and ZigBee devices are able to detect each other's signal and CSMA/CA algorithms are applied accordingly. To study this phenomenon, a series of experiments were carried out, followed by thorough analysis of the recorded data. The study led to the design of a simple but effective technique named Protective Dummy-byte Preamble Padding (PDBPP) that improves the performance of ZigBee packet transmission in terms of packet loss rate (PLR) and transmission efficiency. The experimental performance evaluation results confirmed the effectiveness of PDBPP in improving PLR and transmission efficiency of a ZigBee network exposed to interference generated by collocated WLAN. Some material in this paper is part of a pending patent.

Recent studies have shown that low-power ZigBee based wireless sensor networks (WSN) are vulnerable to the interference generated by Wi-Fi nodes. In this study, the effects of energy detection (ED) mechanism in clear channel assessment (CCA) of ZigBee transmitter under 802.11g Wi-Fi interference have been evaluated through experimentation. To improve the performance of ZigBee packet transmission, a preliminary adaptive mechanism is implemented and evaluated in our testbed.

The low-power, low-rate ZigBee/IEEE 802.15.4 wireless sensor network (WSN) is vulnerable to the interference from a collocated wireless local area network (WLAN), which operates with considerably higher power in the same 2.4GHz Industrial, Scientific, and Medical (ISM) band. In this paper, a novel and effective Interference Aware Adaptive Clear Channel Assessment (IAACCA) technique is proposed to countermeasure the presence of interference with consequence to improve the performance of packet transmission between ZigBee nodes. The performance evaluation has been done through experimentation performed on a testbed implemented by the authors.

The exact analysis of dynamic channel allocation (DCA) with first-in/first-out (FIFO) queuing of handover (QH) requests is highly complex, due to the dynamic nature of channel allocation to different cells. This letter presents an approximate but accurate analytical method to evaluate the performance of DCA in conjunction with FIFO-QH in low earth orbit mobile satellite systems. The accuracy of the proposed analysis has been verified by means of computer simulation.