The self-installation nature of femtocells sharing the same frequency band can lead to harmful femto-to-femto interference levels. The possibility for operators to share its licensed spectrum allows femtocells of one operator to exploit the frequency resources of other operators. In this paper we propose and analyze the performance of two dynamic frequency selection algorithms that permit to the generic femtocell the smart selection of its operating band, among those available from every operator, starting from the measurements of local interference.
The performance of the proposed techniques are analyzed by simulation in terms of outage probability and the achievable Signal-to-Interference Ratio (SIR). It is observed that, in a multioperator scenario this approach offers significant improvement in terms of achievable network capacity and quality of service to customers.

Introduction to SANDRA

The SANDRA concept consists of the integration of complex and disparate communication media into a lean and coherent architecture that:

• provides and manages seamless service coverage across all airspace domains and all aircraft classes
• sustains growth in the service market and enables easy plug – in of future radio technologies through modularity and reconfigurability
• is upgradeable, easy reconfigurable and radio technology independent
• is distributed and instantiated into consistent ground – based and airborne sub – networks ensuring full interoperability.

SANDRA covers from RF and avionics components up to the middleware layer of the on – board network, assembled and integrated under the most stringent safety and security requirements. Ultimately, SANDRA pursues the architectural integration of aeronautical communication system using:

• well – proven industry standards like IP, IEEE 802.16 (WiMAX), DVB – S2, Inmarsat SwiftBroadBand
• a set of common interfaces
• standard network protocols having IPv6 as final unification point to enable a cost – efficient global and reliable provision of distributed services across all airspace domains and to all aircraft classes.

The SANDRA validation activity will show the ability of the proposed integrated architecture to easily reconfigure and adapt for the flexible implementation of new communication services.

This paper describes implementation and computational performance of a proof-of-concept, real-time, fully-software receiver for Digital Video Broadcasting Terrestrial (DVB-T) signals named SRDVB. Following the Software Defined Radio (SDR) paradigm, all the signal processing functions are implemented through C++ software modules developed from scratch by the authors within an SDR framework called newRADIO. The well-know ETTUS Research Universal Software Radio Peripheral (USRP) provides Radio Frequency (RF) front-end and analogue to digital conversion for the system. Design choices and an SDR implementation technique called Memory Acceleration (MA) which made it possible to reach real-time performance even on low-end, off-the-shelf personal computers (PCs) are also outlined within this work.