ABSTRACT
Interference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185 7.2.1 Empirical Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
7.2.1.1 ZigBee in the Presence of a WLAN Interferer . 187 7.2.1.2 ZigBee in the Presence of a Microwave Oven
Interferer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 7.2.1.3 ZigBee in the Presence of both WLAN and
Microwave Oven Interferers . . . . . . . . . . . . . . . . . 190 7.2.2 Mathematical Modeling and Simulation . . . . . . . . . . . . . . . . . . . . 191
7.2.2.1 ZigBee in the Presence of Bluetooth
Interference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196 7.2.2.2 ZigBee in the Presence of WLAN Interference 198
7.3 Interference Avoidance/Mitigation Algorithms . . . . . . . . . . . . . . . . . . . . . . 200 7.3.1 Self-Interference Avoidance Algorithms . . . . . . . . . . . . . . . . . . . . 200
Self-Interference
Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 7.3.1.2 Adaptive Interference-Aware Multi-Channel
Clustering Algorithm . . . . . . . . . . . . . . . . . . . . . . . . 203 7.3.1.3 Adaptive and Dynamic Interference Avoidance
Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206 7.3.2 Network-aided Interference Mitigation Algorithms . . . . . . . . . 208
7.3.2.1 Portable Device Aided Coexistence Algorithm 210
7.3.2.2 Network-Centric Inter-System Interference
Mediation Algorithm . . . . . . . . . . . . . . . . . . . . . . . . 216 7.4 Discussion on Cognitive Radio as an Interference Mitigation
Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 7.4.1 Cognitive Radio for Interference Mitigation: RawPEACH
Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222 7.4.2 Performance Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224
7.5 Summary and Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228
As a ubiquitous communication era is emerging, various types of communication
protocols are expected to support diverse services with different requirements. In
particular, wireless local area networks (WLANs) like WiFi and wireless personal
area networks (WPANs) such as Bluetooth and ZigBee networks may coexist in the
same frequency band. However, since there is no central interference coordinator,
they may interfere with each other. Especially, since ZigBee devices have relatively
lower power emission, compared with other network protocol devices, they may suf-
fer from severe interference, resulting in significant performance degradation. There-
fore, we need to solve underlying coexistence problems between ZigBee and other
networks. This chapter consists of two main parts. In the first part, the performance
analysis of ZigBee networks is described in the presence of interference from het-
erogeneous communication systems. The performance of ZigBee networks is inves-
tigated based on both measurements in a real testbed environment and mathematical
analysis using a Markov chain concept. In the second part, two types of interference
avoidance/mitigation algorithms are introduced in order to enhance the performance
of ZigBee networks in overlaid networks environments. A cognitive radio concept as
interference mitigation technology is also discussed.
