Fourth generation communications calls for a high amount of computational power, due to multiantennas and multimode features. The level of flexibility required is growing rapidly with the number of modes to be supported for a single protocol and the number of protocols to be supported by a single receiver. Such high level of flexibility becomes a key feature of new and legacy radios applications in many domains (military radio, broadcast systems, aeronautic communications, etc.), which call for adopting a software-defined radio (SDR) approach or even for incorporating additional adaptive capabilities, such as suggested by cognitive radio (CR) research. For instance, CR is proposing promising solutions to improve spectrum usage thanks to new opportunistic access to spectrum resources.

In general, the design of flexible baseband platforms raises several critical problems, including the high level of required performance the dissipated power and the reconfiguration process itself. Several alternatives have been partially explored to implement flexible baseband building blocks, and a lot of research is still required to bring efficiency into programmable platforms.

The aim of the special issue is to collect recent contributions as far as review papers on this important and challenging research area. Potential topics include, but are not limited to:

• Channel decoding
• Multiuser and MIMO detection
• Turbo equalization and iterative processing
• Digital demodulation
• Hardware accelerators for flexible radios
• Digital front end architectures
• Design methodologies for reconfigurable platforms
• MPSoC- and NoC-based platforms
• Partial reconfiguration of FPGA for flexible radio
• Low-power solutions
• Reconfiguration management
• Hardware/software codesign
• Software approach to flexible radio implementation

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