# Software-Defined NB-IoT Uplink Framework--The Design, Implementation and Use Cases
## 6 Analysis of the Results and the Use Cases
It means that the impact in the total uplink efficiency of the blocks from CRC module to the mapping to physical resources increases for the good propagation conditions, which results in using the multitone transmission that is available only in the \(\Delta f=15\) kHz subcarrier spacing variant. Thus, the 128 point FFT and IFT transformations are used rather than the 512 point one, which, with the less number of matrix operations during OFDM symbols formulation, leads to more meaningful impact in that block chain. Based on the obtained results, especially from the educational point of view, it is important to learn the relations between the decomposed sections of the modules. In Figures 8 and 9, the decomposed functional sections and their normalized execution times, with respect to the total execution times of the whole framework, are presented as box-and-whisker plots. It consists of the boxplot limited by the first quartile (25 th percentile), median, and third quartile (75 th percentile) values, and whisker that points to the minimum and maximum values. However, the minimum and maximum values are the lowest and highest data points excluding the outliers, which were marked as additional dots in the figures. In addition, in Table 8, the calculated reference normalized execution time results including the outliers are presented, for each integrated or decomposed module. The NB-IoT scrambling, i.e., the pseudorandom sequence generation for the NPUSCH formulation, is one of the most computationally intensive modules in this chain. In this  
Figure 7: Normalized execution time of all the modules except the OFDM generation as a function of the generated number of radio frames. module, the sequence which is further used for generating the scrambling sequence and scrambled with the input code word must be initialized. As it can be seen, the bitwise operations, if properly implemented even with the use of procedural C/C++ language, are more efficient than operations on the floating point values. However, modules that occur after the scrambling one, even when they are operating on the floating point complex signals, are still processed faster. This results from the effectiveness of the low-leveled memory blocks copying and performance of the FFT library [39] with assembler parts. It should be also noted that the DMRS module uses the same scrambling methods as in the scrambling module. However, the difference is in the output of the scrambling base module. The output length is based on the \(N_{RU}\) and \(N_{slots}^{UL}\) and the number of repetitions, which results in a much higher amount of data for analysis, with respect to the DMRS sequences that can be copied efficiently into the proper RUs. This section of the uplink signal processing can be efficiently implemented in the FPGA, especially taking into consideration the bitwise operations and the parallel processing ability. This can be crucial, especially in the harsh propagation environments where the number of security mechanisms needed to be used in order to provide the quality of service (QoS) in the wireless sensor networks (WSNs) is higher. In addition, such approach of duplicating the modules in the hardware is highly desirable from the educational point of view. Learning the process of designing and developing the proper projects may show a great advantage of using the FPGA in the signal processing performed in the dynamically reconfigurable remote radio heads in the LTE eNB and the 5G New Radio Next Generation NodeB (NR gNB), and also enable the use of practical solutions based on the theoretical description. Figure 8: Normalized execution time of modules in the block chain between CRC and mapping to physical resources. On the other hand, as was previously presented, the OFDM generation module is computationally demanding, mainly due to the numerous matrix operations. Each OFDM symbol preparation is based on the IFFT processing and the CP attachment, which is essential in providing the orthogonality.