Table 1 Summary of transmit signal model in the standardized digital mobile systems
Generation | Modulation | Frequency spacing (F) | Symbol period (T) | Pulse shaping g tx(t) | Signal generation s(t) (simplified) : |
|---|---|---|---|---|---|
2G | GMSK | Single Carrier Only | Laurent pulses | \(s(t)\approx \sum _{n} j^{A_{n}} g_{\text {tx}}(t-nT) \) A n : Laurent approximation of n-th transmit symbol | |
3G | DSSS | Single Carrier Only | Root Raised Cosine | \(s(t)= \sum _{n} a_{n} \sum _{c=1}^{N} s(c) g_{\text {tx,c}}(t-n T/N)\) c: chip of a spreading code | |
4G | CP-OFDM (DL) | 15 or 7.5 kHz | T F=1.07 or 1.25 | Rectangular | \(s(t)= \sum _{m} \sum _{n} a_{m,n} g_{\text {tx}}(t-nT) e^{j2\pi m F t}\) |
DFTs-OFDM (UL) | Single carrier T F=1.07 or 1.25 | Dirichlet | \(s(t)= \sum _{n} a_{n} g_{\text {tx}}(t-nT)\) | ||
5G | CP-OFDM compatible | Configurable set | Configurable set | Configurable set | \(s(t)= \sum _{m} \sum _{n} a_{m,n} g_{\text {tx}}(t-nT) e^{j2\pi m F t}\) |
waveform | |||||