Design challenges of open spectrum access

The use of licensed spectrum for wireless communication is driven by the need to control interference between different operators. However, with this mode of regulation, spectrum utilization is far from efficient and the growth of wireless networks is hindered by the shortage of free frequency bands and the vast investments for the acquisition of a license. In view of this situation, we present an alternative evolution path for the unobstructed growth of wireless networks and the efficient use of spectrum. The proposed architecture is based on the use of unlicensed spectrum and the open access of users to all public networks without prior contracts with operators. We highlight and discuss the inherent technical challenges that must be tackled before the proposed solution can be realized. Special attention is paid to the inherent need for alternative interference mitigation strategies.