The Signal Processing Challenges of Flexible Radio

Digital radio communication systems today typically operate well short of the theoretical capacity of the channel. This paper discusses how far greater bandwidth efficiency can be obtained on wireless channels through the use of adaptive procedures in the transmitter. These procedures require knowledge of the channel which is acquired at the receiver and fed back to the transmitter via a high integrity path. The use of reconfigurable hardware is an important aspect of this approach. The challenges involved in the deployment of adaptive modulation, adaptive precoding, flexible channel coding and cognitive radio systems are described