# Is Satellite Ahead of Terrestrial in Deploying NOMA for Massive Machine-Type Communications?
## 4 Developed E-SSA-Based NOMA System Elements
### The HyperCube Platform (MBI)  
The first F-SIM gateway commercial solution, named HyperCube, was developed by MBI in 2014 in collaboration with Eutelsat and the support of the European Space Agency (ESA) for the operation of the Eutelsat network in combination with SmartLNB terminals. The HyperCube platform is one of several different hardware and protocol evolutions of the first software-defined radio (SDR)-based prototype gateway used in 2009 to receive the very first E-SSA transmission (S-MIM) over the Eutelsat W2A satellite operating in the S band. The HyperCube platform is a bidirectional, satellite-based interactive system that provides an IP-based, fully compatible and transparent communication between a population of SmartLNBs (the satellite terminals) and the Internet backbone. It has been developed and commercially provided by MBI. A high-level architecture of the HyperCube platform is illustrated in Figure 10, in which the hub controls both the forward link (FL) gateway (GW) and the return link (RL) GW. As it can be seen in Figure 10, HyperCube supports an IP-routed environment, in which the hub behaves as an IP router across the different network segments. Customer-based specific routing policies are also supported. The terminal at the remote side can behave as an IP router too, which is capable managing its own local area network (LAN). A more detailed HyperCube platform functional block diagram is shown in Figure 11. A compact and turn-key HyperCube platform in its entry level version can easily fit within a 19\" rack, as shown in Figure 12.  
Figure 9: The Satixfy Diamond Ku-band antenna. Figure 11: Detailed block diagram of the HyperCube platform. Figure 10: High-level functional block diagram of the HyperCube platform. The HyperCube platform elements shown in Figure 11 have been integrated in a single 19\({}^{\prime\prime}\) rack hosted in the satellite GW (see Figure 12). In the case of a multi-beam high-throughput satellite (HTS) (e.g., Eutelsat Ka-Sat), each GW serves a subset of the HTS beams. The size of the beam cluster served by each gateway is related to the feeder link bandwidth. In this case, a number of FL/RL HyperCube GWs have to be geographically distributed. Such remote FL/RL GWs have been connected to the central hub through an IP-based backbone thanks to the modular HyperCube architecture. The RL side of the GW is based on a software-defined radio (SDR) architecture (see Figure 13): it adopts an off-the-shelf SDR device to perform down-conversion to the baseband, and to convert, through analogue-to-digital, the aggregated signal. Then, the I-Q digital samples are delivered through a 10 GBE connection to the demodulation chain composed of a number of demodulation nodes connected in a cascade configuration. Each node is built using a rack-mountable server equipped with a central processing unit (CPU) and graphical processor unit (GPU) that share the computational processing. All the digital signal processing (DSP) algorithms required to demodulate F-SIM bursts are executed in the software by running the C++ object code hosted on each demodulation node. DSP algorithms are based on the Intel Math Kernel Library and the NVIDIA Compute Unified Device Architecture (CUDA), respectively, for CPUs and GPUs. This SDR approach has changed the way gateway demodulator processing is developed, once only based on the traditional field-programmable gate array (FPGA) approach. In particular, this approach allows increasing the performance by adopting the newest CPUs/GPUs released on the market by major manufacturers, with marginal costs for the porting of the code. After about ten years of continuous operations, the viability of the SDR approach for the ground segment of the random access E-SSA system has reached full maturity. Figure 12: HyperCube platform hosted in a 19\({}^{\prime\prime}\) rack.