Opportunistic unsynchronized cognitive radio networks

In this presentation, a new wireless communication scheme “adaptation-to-environment type baseband radio” which realizes a software radio and/or cognitive radio concept is proposed, and a fundamental experiment is performed to confirm the feasibility of the proposed scheme. The baseband radio discussed here means the scheme which generates a radio wave directly by baseband digital signal processing. Although the transmission scheme proposed as an example is similar to OFDM modulation, a major difference is to radiate the baseband signal directly from an antenna as a real number signal without carrying out an up conversion to radio frequencies. A preliminary experiment for transmitting QPSK and 16QAM signals is carried out. The results show that very flexible error-free transmission can be realized based on the proposed baseband radio.