Electrical Engineering
      and Computer Sciences

Electrical Engineering and Computer Sciences

COLLEGE OF ENGINEERING

UC Berkeley

   

2009 Research Summary

Challenges of Coexistence Between 802.15.4 and 802.11

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Ahmad Bahai, Sofie Pollin, Ian Tan and Carl Chun

National Semiconductor, European Commission and Interuniversity Micro-Electronics Center (IMEC)

Due to recent advances in wireless technology, a broad range of standards catering to a diverse set of users are currently emerging. Interoperability and coexistence between these heterogeneous networks are becoming key issues, and proper mitigation of these issues requires a good understanding of how and why heterogeneous networks may harm each other’s performance. In this project, we focus on the coexistence of 802.11 (wireless LAN) and 802.15.4 (sensor networks) in the ISM band. These networks have very different transmission characteristics that result in asymmetric interaction patterns. Consequently, many studies assume that the impact of 802.15.4 on 802.11 is negligible. After examining this assumption in detail we show that, in many cases, 802.15.4 significantly impacts 802.11 performance. Even when 802.15.4 is executing a listen-before-send, which should theoretically prevent interference, a notable 802.11 performance degradation frequently occurs due to disparate slot sizes between the two protocols. These results raise important coexistence issues for 802.15.4 and 802.11 in particular, but even more so for dynamic spectrum sharing between heterogeneous devices in general.

[1]
S. Pollin, I. Tan, B. Hodge, C. Chun, and A. Bahai, "Harmful Coexistence Between 802.15.4 and 802.11: A Measurement-based Study," International Conference on Cognitive Radio Oriented Wireless Networks and Communications, 2008.