Healing plasma current ramp-up by Nitrogen seeding in the full Tungsten environment of WEST

Achieving a successful plasma current ramp-up in a full Tungsten tokamak can be challenging due to the large core radiation (and resulting low core temperature) that can be faced with this heavy metallic impurity if its relative concentration is too high. Nitrogen injection during the plasma current ramp-up of WEST discharges greatly improves core temperature and Magneto-Hydro-Dynamic stability. Experimental measurements and integrated simulations with the RAPTOR code complemented with the Qualikiz Neural Network for computing turbulent transport allow a detailed understanding of the mechanisms at play. Increased edge radiation during this transient phase is shown to improve confinement properties, driving higher core temperature and better MHD stability. This also leads to increased operation margins with respect to Tungsten contamination.

6G Vision and Challenges: Complexity Analysis of M-MIMO Rate-less Based System with Various Pre-Coding Schemes

Due to the expected essential role of the rate-less digital fountain codes and Massive-Multi-Input Multi-Output (M-MIMO) techniques in the 5G and 6G mobile wireless networks, this paper investigates the performance of M-MIMO enhancing system employing the Raptor code. The proposed M-MIMO-Raptor code based system has been tested over the different wireless communications channel conditions with respect to the various Frequency Doppler (FD). The various promising technologies for the beyond 5G and 6G have been presented with focusing on the advanced error control techniques. The flexible adaptive interleaved pre-code based on the channel conditions is suitable for 6G mobile wireless networks which integrates the various environments of the communications. The complexity of the advanced and fixed code rate schemes is discussed. Several computer simulation experiments are carried out for evaluating the performance of M-MIMO-rate-less code system. These experiments prove the superiority of the presented wireless rate-less system compared to the fixed rate wireless system due to the improved results of BER and the throughput values which are utilized as a performance evaluating metrics. Theoretical analysis of the M-MIMO throughput proves the enhancing of M-MIMO utilizing the rate-less Raptor code and its applicability for the next mobile wireless networks generations.

Rateless Coded Uplink Transmission Design for Multi-User C-RAN

Cloud radio access network (C-RAN) is a promising technology for the Internet of Things (IoT). In C-RAN, the remote radio head (RRH) and baseband unit (BBU) in the conventional base station are separated, and each BBU is backward centralized into a virtual BBU pool. In this paper, we consider the uplink transmission for the two-user C-RAN with two RRHs under a block fading channel. A novel rateless coded transmission scheme is designed. During each transmission round, each user keeps transmitting to the RRHs using Raptor code until the BBU pool feeds back an acknowledgement (ACK). With the proposed scheme, each user does not require the instant channel state information, which greatly reduces the system overhead. We also design the quantizer at the RRHs and the iterative multi-user detector and decoder at the BBU pool, based on the belief propagation (BP) algorithm. For the Raptor code applied at each user, we optimize the corresponding output node degree profile, based on extrinsic information transfer (EXIT) analysis for the decoding process at the BBU pool. The resulted degree profiles are optimal in an average sense under all possible channel states. The simulation results show that the rateless coded transmission scheme with the optimized degree profiles outperforms the benchmark degree profile in both bit error rate and average system throughput. Moreover, the achieved performance is close to the theoretical limit.