Table 210 Summary of GFDM statement comments 1 A general framework to partition the GFDM has the flexibility of covering regular CP-OFDM given time/frequency resource based on (e.g., ), or SC-FDE (e.g., ). specific requirements[14] 2 OOB leakage can be improved by Most of the suppression comes from windowing (similar as prototype filter [14]. Tx-WOLA). Spectrum property of the prototype filter is lost from non-smooth transition between blocks, as shown in Figure 232. 3 Prototype filter may require more Maybe can get rid off special prototype filter, as it gives no complicated modulation/receiver, e.g. obvious benefit in OOB suppression. OQAM, similar as in FBMC. Figure 231 GFDM modulator and demodulator with rectangle pulse shaping Figure 232 PSD of GFDM with and without windowing Figure 233 PSD of GFDM with windowing for different clipping at transmitter Summary of waveform synthesis implementation In general, most of FFT/IFFT based waveform synthesis can be practically implemented based on the diagram shown in Figure 234. Note that is essentially a guard sequence of zeros prior to the waveform synthesis blocks, while “zero-tail” refers to post-fix of zeros and is the standard cyclic prefix constructed from the tail of the IFFT block “zero-guard” “CP” output. The zero-guard absorbs the filter delay imposed by UFMC, as shown in a previous section. Figure 234 Waveform synthesis using FFT/IFFT Notice that for a specific waveform synthesis, certain blocks are simply bypassed depending on the waveform to be synthesized. To compare the implementation of different waveform synthesis, we summarize in Table 211 which blocks are skipped/enabled for individual waveform, respectively. Table 211 Waveform synthesis implementations
Table 210 Summary of GFDM statement comments 1 A general framework to partition the given time/frequency resource based on specific requirements[14] GFDM has the flexibility of covering regular CP-OFDM (e.g., ), or SC-FDE (e.g., ). 2 OOB leakage can be improved by prototype filter [14]. Most of the suppression comes from windowing (similar as Tx-WOLA). Spectrum property of the prototype filter is lost from non-smooth transition between blocks, as shown in Figure 232. 3 Prototype filter may require more complicated modulation/receiver, e.g. OQAM, similar as in FBMC. Maybe can get rid off special prototype filter, as it gives no obvious benefit in OOB suppression. Figure 231 GFDM modulator and demodulator with rectangle pulse shaping Figure 232 PSD of GFDM with and without windowing Figure 233 PSD of GFDM with windowing for different clipping at transmitter Summary of waveform synthesis implementation In general, most of FFT/IFFT based waveform synthesis can be practically implemented based on the diagram shown in Figure 234. Note that “zero-tail” is essentially a guard sequence of zeros prior to the waveform synthesis blocks, while “zero-guard” refers to post-fix of zeros and “CP” is the standard cyclic prefix constructed from the tail of the IFFT block output. The zero-guard absorbs the filter delay imposed by UFMC, as shown in a previous section. Figure 234 Waveform synthesis using FFT/IFFT Notice that for a specific waveform synthesis, certain blocks are simply bypassed depending on the waveform to be synthesized. To compare the implementation of different waveform synthesis, we summarize in Table 211 which blocks are skipped/enabled for individual waveform, respectively. Table 211 Waveform synthesis implementations