ay increase. It requires a mini modem and router in each LEO satellite (https ://www.satellitephonereview.com/networks/). There are a few other alternatives to bent-pipe architecture, such as regenerative architecture and onboard processing architecture. In the regenerative architecture, the satellite processes the signal before retransmitting it. NG over Feeder link Uu over Service link Satellite Figure 16.16 - Satellite regenerative architecture We can see in Figure 16.16 that the Core Network (CN) is terrestrial, and the Radio Access Network (RAN) is in the satellite. In the case of bent-pipe architecture, both the CN and RAN are terrestrial, keeping the satellite's system simple. In this scenario, the satellite systems may also do error correction and signal quality improvement before retransmitting it. In the onboard processing architecture, the satellite may perform tasks such as error correction, encryption, and modulation. This makes the onboard processing more complex. However, it can make the satellite system more reliable efficient. It drives up the cost of satellite systems. Knowledge of 3GPP specifications such as R-17 and R-18 and their coverage of NTN helps to decide which satellite system to utilize when architecting a satellite-based 5G solution. While LEO provides lower latency (30 to 50 ms), it will have lower geographical coverage when compared to MEO/GEO. In turn, MEO and GEO have a lower deployment cost per unit of geographical coverage. For an LEO system, there will be different satellites in view of the UE, leading to handoffs. That can make the design of the 5G system more complex. 5G and Satellite Communications Next, let us look at the different spectrum frequencies allocated by 3GPP for NTN. There are two main Frequency Range (FR) groups, namely FR1 and FR2, as shown in Table 16.1: Frequency Range Bands 450 MHz to 6 GHz S-band and L-band 24.25 GHz to 52.6 GHz Not applicable For NTN, 3GPP has ratified the following S-band and L-band for FR1: S-band: It ranges from 1,980-2,010 MHz and 2,