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Cognitive radio (CR) is a promising technology that can enhance the radio spectrum utilization by enabling unlicensed users to exploit the spectrum in an opportunistic manner. However, the main challenge is to share the licensed spectrum without interfering transmissions of other licensed users. A CR node needs to vacate the spectrum upon detection of licensed users on a particular frequency band (e.g., spectrum handoff or spectrum mobility) leading to significant network performance drops and switching overheads. This chapter aims to propose a proactive spectrum handoff management scheme to overcome the problem of handoff latency management in CR ad hoc networks. The proposed scheme is modeled and its performance is evaluated using an OPNET simulation tool. Simulation results are presented to evaluate the performance of the proposed system. The chapter concludes with a brief discussion and future research directions.

Next generation wireless networks will be heterogeneous, where several primary users (PU e.g. licensed users) and secondary users (SU e.g. unlicensed users) can operate in the same dynamic and reconfigurable networks at a given time. The major challenge in this heterogeneous radio environment is to enable the coexistence between PU and SU which will further improve the efficient use of radio spectrum. Most of the existing coexistence techniques encounter with challenges due to lack of a priori knowledge about the primary system. Therefore Cognitive pilot channel (CPC) is a proposed approach which could enhance the coexistence by conveying some priori information. However, to achieve a peaceful coexistence it is essential to adopt a mitigation technique according to the CPC information. There is no algorithm has been described so far to integrate the CPC information with existing mitigation technique. In this paper, we proposed a novel power adaptation and integrated zone model (PAIZM) CPC algorithm for peaceful coexistence in heterogeneous networks. Moreover we have implemented and evaluated the PAIZM-CPC model as a coexistence enabler. The results show an enhancement compared with the existing coexistence techniques.

Next generation wireless networks will be heterogeneous, where several primary users (PU e.g. licensed users) and secondary users (SU e.g. unlicensed users) can operate in the same dynamic and reconfigurable networks at a given time. The major challenge in this heterogeneous radio environment is to enable the coexistence between PU and SU which will further improve the efficient use of radio spectrum. Most of the existing coexistence techniques encounter with challenges due to lack of a priori knowledge about the primary system. Therefore Cognitive pilot channel (CPC) is a proposed approach which could enhance the coexistence by conveying some priori information. However, to achieve a peaceful coexistence it is essential to adopt a mitigation technique according to the CPC information. There is no algorithm has been described so far to integrate the CPC information with existing mitigation technique. In this paper, we proposed a novel power adaptation and integrated zone model (PAIZM) CPC algorithm for peaceful coexistence in heterogeneous networks. Moreover we have implemented and evaluated the PAIZM-CPC model as a coexistence enabler. The results show an enhancement compared with the existing coexistence techniques.