output symbol 1 IFFT output symbol 2 Transmit filtering x[k] = F. n, k Vn, n, S n. Nsb-1 Transmit waveform symbol 1 Transmit waveform symbol 2 S(Nsb-2)n UFMC processing at the transmitter FFT size S(Nsb-1)n Received waveform Zero padding Subband block filtering 2x size FFT input UFMC processing at the receiver Figure 3.23 UFDM signal processing [42,47]. New Radio Access Physical Layer Aspects (Part 1) 343 3.2.3.4 Generalized Frequency Division Multiplexing Generalized frequency division multiplexing (GFDM) is a flexible multicarrier modulation scheme. The process is performed block-by-block, where each GFDM block consists of a number of K subcarriers and M sub-symbols. By setting the number of subcarriers and the number of sub-symbols to one, GFDM reduces to single-carrier frequency domain equaliza- tion and CP-OFDM as its special cases. Furthermore, pulse shaping with a prototype filter go,((n) is another flexibility in GFDM to reduce OOB emissions. In contrast to linear convo- lution used in FBMC, GFDM uses circular convolution. Let gk,m(n) denote the pulse- shaping filter corresponding to the data symbol Sk,m that is transmitted at subcarrier m and time k. It can be shown that In the above equation N denotes the number of symbols within a GFDM block (GFDM block size). Thus, the time-domain signal x(n) of a GFDM block is expressed as n=0,1,...,N - A CP and a cyclic suffix can be optionally added in the GFDM data block. Furthermore, a raised-cosine filter with configurable roll-off factor B is used for filtering. The GFDM sig- nal processing stages are illustrated in Fig. 3.24. M samples across S0,0 *** SO,M- SK-1,0 ... SK-1,M-1 g(n) n =0,1 LEN- LF M S N (n) pj2tknIN OFDM Data Data Data Data Data (K-2)n (K-2)n W(K-1)n (K-1)n Figure 3.24 Illustration of GFDM signal processing [45,47]. Chapter 3 GFDM signal in the frequency domain OFDM signal in the frequency domain FFT bins Figure 3.25 Comparison of OFDM and GFDM signals in the frequency domain [38]. In one aspect, GFDM is similar to FBMC where a prototype filter