Coexistence Techniques for Heterogeneous Mobile Devices Operating in Uncoordinated Radio Spectrum

This dissertation, "Coexistence Techniques for Heterogeneous Mobile Devices Operating in Uncoordinated Radio Spectrum" by Cho-hoi, Michael, Chek, 戚祖凱, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled Coexistence Techniques for Heterogeneous Mobile Devices Operating in Uncoordinated Radio Spectrum submitted by CHEK Cho Hoi, Michael for the degree of Master of Philosophy at the University of Hong Kong December 2003 Short range wireless technologies are becoming increasingly important in enabling useful mobile applications. Bluetooth and IEEE 802.11b standards are the most commonly deployed technologies for WPAN and WLAN. However, because both standards share the same unlicensed ISM (Industrial, Scientific, Medical) radio spectrum, severe interference is inevitable and performance can be impaired significantly when heterogeneous devices using the two technologies come into close proximity. The most notable solution to this problem is a frequency domain non-collaborative coexistence mechanism called adaptive frequency hopping (AFH). However, we find that the efficiency of the "channel classification" sub- process in non-collaborative mechanisms is by and large ignored in the literature. Moreover, we also find that there is no system resources awareness and no interference source genre concerns in IEEE 802.15 Task Group 2 AFH (TG2 AFH) design. Thus, we suggest a new approach called ISOAFH (Interference Source Oriented AFH). With the above considerations, we propose a customized channel classification process, thereby simplifying the time and space complexity of the mechanism. Through our detailed implementation of various coexistence mechanisms in MATLAB Simulink, it is observed that TG2 AFH performance is sensitive to memory and power limitations, while ISOAFH is much less sensitive to these constraints and can keep a much lower channel collision rate. On the other hand, in this thesis we also study some open issues of a time domain mechanism called MDMS (Master Delay MAC Scheduling). We compare different coexistence mechanisms and find that the performance of each approach very much depends on the efficiency of its sub-processes. Through our experiments, we also determine the optimal operating points for different coexistence mechanisms. In particular, we find that AFH is effective for achieving good system performance and spectrum utilization, while MDMS with multi-slot packets is good when AFH is impractical and environmental interference level is less than 60%. (Total words: 302) Signature DOI: 10.5353/th_b2933072 Subjects: Radio - Interference Wireless communication systems Mobile communication systems