A node architecture for disaster relief networking

In this paper we present node architecture for a personal node in a cognitive ad-hoc disaster relief network. This architecture is motivated from the network system requirements, especially single-hop distance and jamming-resilience requirements. It is shown that the power consumption of current-day analog to digital converters (ADCs) limits the channel bandwidth that can be used, both for a baseband processing system and the scanning system. We therefore propose to use a form of frequency hopping time division multiplexing (FH/TDD) system, similar to Bluetooth. However, we propose to use OFDM as modulation scheme instead of GFSK and show that the OFDM symbol length for the frequency range at hand (400-1000 MHz) is consistent with a Bluetooth-alike FH/TDD scheme. We propose to modify the FH/TDD scheme to incorporate a radio-spectrum measurement phase. Based on these measurements carriers in the OFDM-based scheme are selected in such a fashion that legacy users are avoided. In case of too much legacy-user spectral usage hopping patterns may be altered