This paper presents an architecture to support dynamic spectrum access (DSA)
in general wireless networks. Our architecture advocates a new spectrum virtualization layer (SVL), directly below the wireless physical layer (PHY or baseband processing).
We call it Layer 0.5.
SVL presents a virtual baseband to traditional wireless PHY, which is designed for a fixed contiguous spectrum band with fixed width. When spectrum allocation changes under DSA,
SVL performs real-time reshaping of baseband signals so that the baseband of traditional wireless PHY maps to the current physical spectrum band allocation, which can be of different width, or even in separate non-contiguous bands.
All operations inside SVL are agnostic and transparent to upper PHY, making it possible to enable DSA without changing the traditional PHY designs.
We have implemented a prototype of SVL on a software radio platform and demonstrated the flexibility and effectiveness of SVL in supporting DSA. We believe this is the right architecture model for enabling DSA for general wireless networks.