Distributed Cognitive Coexistence of 802.15.4 with 802.11: Paper

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Distributed Cognitive Coexistence of 802.15.4 with 802.11: Paper

Introduction
Interest in wireless technology has experienced an explosive growth over the last decades. The finalization of diverse standards has eased the development of wireless applications. As a result, the spectrum is getting used by a variety of heterogeneous devices, standards, and applications. This is especially the case for the Industrial, Scientific, and Medical (ISM) bands that are unlicensed and hence host the most heterogeneous range of networks.

In this paper we focus on the coexistence between two major wireless standards that operate in the 2.4GHz ISM band, namely 802.11g Wireless LAN and 802.15.4 Sensor Networks. The characteristics of both networks are very different, resulting in a problem that is asymmetric in nature. Indeed, the output power of 802.15.4 devices is typically as low as 0dBm, whereas the output power of 802.11g devices is 15dBm or above. Also, 802.15.4 sensor networks are designed to monitor the environment or buildings, and can be very large, while 802.11 networks are mostly local hotspots organized around an Access Point (AP). Finally, sensor network applications are not demanding in terms of throughput, but however require a high reliability and robustness against attacks or unknown events. They should also be self-organizing since it is impossible to maintain such large networks efficiently. In comparison, 802.11 networks are typically used by a limited number of throughput-intensive applications. There is in fact only one common requirement: both 802.15.4 and 802.11 devices are battery-powered so that energy consumption is a major design criterion. Any algorithm for those networks should take the energy cost into account, including the non-negligible hardware power contribution associated with idle mode operation, scanning and receive processing.

Read the full Distributed Cognitive Coexistence of 802.15.4 with 802.11 White Paper.