Efficiency of Filter Bank Multicarrier Techniques in Burst Radio Transmission

The filter bank multicarrier (FBMC) technique has been proposed in the FP7 European research program, as an enhancement to the OFDM technique for future broadband radio systems. Besides gains in efficiency, mainly due to the absence of cyclic prefix, an important feature of FBMC is the absence of spectral leakage, which makes it particularly appealing for cognitive radio. However, in burst transmission, the filter impulse response introduces transitions which extend the length of the burst with respect to OFDM and may reduce the gains in efficiency. After a brief overview of the FBMC technique, the exploitation in burst transmission is discussed. The effect of cutting the initial and final transitions of the burst is investigated. The level of temporary spectral leakage introduced by this operation is assessed. It is shown that cuts leading to an increase in burst length of half a symbol with respect to OFDM affect the first and the last symbol only, resulting in a minor reduction in bit loading for these symbols. Application to the time division duplex access mode is considered, as well as the case of the presence of a preamble in the burst. For implementation, it is proposed to resort to a simple memory preloading technique, which has the advantage of compatibility with OFDM in dual mode systems.