The radio frequency spectrum is becoming scarce. Conventional fixed spectrum allocation however results in low utilization of the allocated spectrum. Cognitive radio is a novel technology which improves the spectrum utilization by allowing secondary networks (users) to borrow unused radio spectrum from primary licensed networks (users) or to share the spectrum with the primary networks (users). As an intelligent wireless communication system, cognitive radio is aware of the radio frequency environment, selects the communication parameters (such as carrier frequency, bandwidth and transmission power) to optimize the spectrum usage, and adapts its transmission and reception accordingly.

Using cognitive radio, tremendous economic benefits can be generated to both telecom operators and customers through reusing the unused or underutilized spectrum. The success of cognitive radio technology however depends on the interdisciplinary research and effort from various technical societies, including, e.g., signal processing, information theory, communications engineering, artificial intelligence as well as cooperation/game theory societies. For example, casual reasoning, which is an active area of research in the domain of artificial intelligence, can provide ways for a cognitive radio to increase its context awareness. Cooperation theory, on the other hand, is one of the highly valuable modeling tools for cognitive radio and cognitive wireless networks which can be used to model system sensitivity against non-cooperating or hostile users.  As the freedom of selecting different operational modes and parameters is increasing with number of terminals, it becomes important to understand what are the limitations and benefits of cooperation in such networked environment.

This special issue aims at bringing together the state-of-art research results on cognitive radio and its applications. We target academic research contribution in cognitive radio dealing with interdisciplinary research, as well as application-oriented contributions dealing with architecture, platform, signaling and multiple access schemes. Original contributions, previously unpublished and not currently under review by another journal, are solicited in relevant areas including (but not limited to) the following:

• Information theory for cognitive radio
• Multiple access scheme for cognitive radio
• Solutions for protecting primary users
• Biologically informed networks for cognitive radio
• Spectrum sensing mechanism and protocol support
• Efficient mulit-ban multi-resolution channel sensing algorithms
• Synchronization and channel estimation for cognitive radio
• Qos provisioning and MAC protocol for cognitive radio
• Radio knowledge representation language (RKRL) for cognitive radio
• Cooperation theory, game theory and causal reasoning for cognitive ratio networks
• Dynamic spectrum management
• Cross Layer design for cognitive radio
• Anti-jamming channel coding
• Interdisciplinary research for cognitive radio

Prospective authors should follow the IEEE J-SAC manuscript format described in the Information for Authors. There will be one round of reviews and acceptance will be limited to papers needing only moderate revisions. Authors should submit a PDF version of their complete manuscript (which should be compressed if the file size exceeds 1 Mbyte) via email to ycliang@i2r.a-star.edu.sg according to the following timetable: