With the upcoming pervasive deployment of wireless networks and devices on the unlicensed band, co-channel interference caused by frequency collisions among coexisting networks have become one of the major performance limiting challenges. In recent years the coexistence issue has gained increasing attention. However, many collision avoidance schemes are not applicable to multiple frequency hopped (FH) networks, mainly due to the fact that the frequency channels of FH signals are constantly changing and the hop sequence of one network to another is unknown. In this dissertation, a comprehensive framework for co-channel interference mitigation and robust coexistence of multiple FH networks is developed. The main components of this framework include a dual channel transmission technique in the medium access control layer, a diversity scheme for single-antenna multi-carrier systems over frequency-selective channels, and a signal processing method for collision resolution based on blind multiuser detection in the physical layer. This dissertation discusses the system modeling, design, theoretic analysis, simulation, and testbed implementation involved in the aforementioned framework. This design enables robust coexistence of multiple uncoordinated FH networks. The diversity techniques and signal processing methods developed in this dissertation are also applicable to other wireless systems.
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