## 3 New Radio Link-Level Simulator
### Transmission Chain
The channel bandwidth and sub-carrier spacing (SCS) determine the size of the IFFT and the number of samples for each OFDM symbol. At this point a cyclic prefix is added at the beginning of each OFDM symbol, through a look-up table, with a duration selected between \"normal\" or \"extended\". The \"normal\" option is selected for the simulations according to the used sub-carrier spacing of 30 kHz. This value is compatible with the maximum delay of the channel that falls into the selected CP length. Oversampling and filteringAn oversampling step increases the number of samples for each symbol by a selected factor and the sampling frequency is increased accordingly. A raised cosine filter is used as the transmitting filter. Receiver sideAt the receiver side, a finite impulse response filter is applied to remove the undesired frequencies and a down-sampler stage re-samples the signal to the normal frequency, by the same factor as the up-sampler. To account for the delay due to the signal transmission and FIR filter, at each iteration, the signal at the receiver side is buffered and processed on a block basis, where the block length in time is equal to the slot duration. The receiver must then reverse all the signal-processing applied by the transmitter with suitable blocks, such as an OFDM signal demodulator, a sub-carrier demapper, and so on. The MIMO processing consists of the application of a combining matrix over the received symbols to exploit the antenna array at the receiver if more than one antenna is configured. The combining matrix can be used for various purposes, i.e., improving the SINR or for separating the different layers if more than one data stream is transmitted using spatial multiplexing. The LDPC decoder applies the offset min-sum (OMS) decoding algorithm. The performance measurements are applied on the CRC detection for the BLER, while the raw BER is computed on the number of actual erroneous bits before the LDPC decoding. The approximate peak throughput of the simulated NR configuration can be calculated by means of the formula provided in the TS 38.306 3 GPP [46] specification:  
\[\text{data rate }[\text{Mbps}]=10^{-6}\cdot\sum_{j=1}^{I}\left(v_{L}^{(j)} \cdot Q_{m}^{(j)}\cdot f^{(j)}\cdot R_{max}\cdot\frac{N_{LRW}^{BW(j),\mu,12}}{T _{s}^{\mu}}\cdot\left(1-OH^{(j)}\right)\right) \tag{1}\]  
where:  
* \(J\) is the number of aggregated component carriers in a band or band combination. * \(R_{max}=948/1024\) is the maximum LDPC code rate. * \(v_{L}^{(j)}\) is the maximum number of layers. * \(Q_{m}^{(j)}\) is the maximum modulation order
* \(f^{(j)}\) is the scaling factor (it can take the values 1, 0.8, 0.75 and 0.4) and is signalled per band or per band combination). * \(\mu\) is the numerology. * \(T_{s}^{\mu}\) is the average OFDM symbol duration in a subframe for numerology \(\mu\) and normal CP, i.e., \(T_{s}^{\mu}=\frac{10^{-3}}{14\cdot 2^{\mu}}\). * \(N_{PRR}^{BW(j),\mu}\) is the maximum RB allocation in maximum UE supported bandwidth BW(j) with numerology \(\mu\). * \(OH^{(j)}\) is the overhead (0.14 for DL FR1-0.18 for DL FR2-0.08 for UL FR1-0.10 for UL FR2).