FMT Modulation for Wireless Communication用于无线通信的调制.pptVIP

FMT Modulation for Wireless Communication Santosh V Jadhav (Advisor: Prof V M Gadre) Multicarrier System: Spectral partitioning: -sinc(f) overlapping (OFDM) -Non-overlapping (FMT) OFDM: FMT : Spectral characteristics:OFDM Spectral characteristics:FMT OFDM Communication System OFDM v/s FMT: OFDM: -perfect detection(zero ISI, zero ICI) under ideal channel and absence of noise. -simple equalization scheme with cyclic prefix -high spectral overlap. FMT: -nearly rectangular frequency-domain amplitude characteristic -High spectral containment, negligible ICI -The absence of the cyclic prefix, together with the reduced no of virtual carriers -Equalizer is required even under ideal channel condition and absence of noise Why to prefer FMT over OFDM? -Cyclic Extension in OFDM - Loss of transmission efficiency -High spectral overlap in OFDM - Frequency offset sensitivity -In OFDM side lobes are just 13dB lower than the main lobe - Significant power leakage into adjacent band FMT System: Direct implementation Efficient implementation: DFT based FMT system - Contd…FMT Receiver- Prototype Design: Prototype filter h(n) completely defines the system. Allows tradeoff between- - No. of subcarriers - Level of spectral containment - Complexity of implementation and latency Can be designed by any standard FIR filter design method. Typical design parameters are- - fcutoff : determines the ISI per subchannel - Stopband energy : determines ICI introduced by adjacent subchannels, so should as low as possible Contd…e.g. - Equalization in FMT System: Due to negligible ICI, each subchannel will be independent of adjacent channel(s) as shown - Simplified