The performance of existing frequency-domain channel estimation and equalization algorithms for faster-than-Nyquist (FTN) signaling is seriously hampered with the noise enhancement phenomenon that results from their inverse or pseudo-inverse operations. Through simulations, we show that the linear precoding can effectively mitigate the above-mentioned noise enhancement phenomenon. At first, a low complexity precoding-based channel estimation (PCE) algorithm is proposed for FTN signaling over frequency-selective fading channels. In contrast with most existing frequency-domain channel estimation algorithms, the proposed PCE algorithm has much better mean square error performance, and the performance improvement enlarges with the increase of signal to noise ratio. Furthermore, a joint channel estimation and precoding (JCEP) algorithm is proposed to perform data detection for FTN signaling over frequency-selective fading channels. On the one hand, compared with the existing frequency-domain channel estimation and equalization algorithms, the JCEP algorithm greatly reduces the complexity of signal processing at receivers since it performs the linear precoding processing at transmitters. On the other hand, even with estimated channel state information (CSI), the proposed JCEP algorithm can approach the bit error rate (BER) performance of the Nyquist signaling for all the modulation types adopted in digital video broadcasting-satellite-second generation extension (DVB-S2X). More precisely, the BER performance degradation with perfect and estimated CSI is 0.06 dB and 0.07 dB respectively when the time acceleration parameter equals to 0.7 and the rolling factor is 0.45.

Beam-hopping technology has become one of the major research hotspots for satellite communication in order to enhance their communication capacity and flexibility. However, beam hopping causes the traditional continuous time-division multiplexing signal in the forward downlink to become a burst signal, satellite terminal receivers need to solve multiple key issues such as burst signal rapid synchronization and high-performance reception. Firstly, this paper analyzes the key issues of burst communication for traffic signals in beam hopping systems, and then compares and studies typical carrier synchronization algorithms for burst signals. Secondly, combining the requirements of beam-hopping communication systems for efficient burst and low signal-to-noise ratio reception of downlink signals in forward links, a decoding assisted bidirectional variable parameter iterative carrier synchronization technique is proposed, which introduces the idea of iterative processing into carrier synchronization. Aiming at the technical characteristics of communication signal carrier synchronization, a new technical approach of bidirectional variable parameter iteration is adopted, breaking through the traditional understanding that loop structures cannot adapt to low signal-to-noise ratio burst demodulation. Finally, combining the DVB-S2X standard physical layer frame format used in high throughput satellite communication systems, the research and performance simulation are conducted. The results show that the new technology proposed in this paper can significantly shorten the carrier synchronization time of burst signals, achieve fast synchronization of low signal-to-noise ratio burst signals, and have the unique advantage of flexible and adjustable parameters.

The power allocation optimization problem is investigated for improving the physical-layer security in two-way relaying networks, where a full-duplex relay based half-jamming protocol (HJP-FDR) is considered. Specially, by introducing a power splitter factor, HJP-FDR divides the relay's power into two parts: one for forwarding the sources' signals, the other for jamming. An optimization problem for power split factor is first developed, which is proved to be concave and closed-form solution is achieved. Moreover, we formulate a power allocation problem to determine the sources' power subject to the total power constraint. Applying the achieved closed-form solutions to the above-mentioned problems, a two-stage strategy is proposed to implement the overall power allocation. Simulation results highlight the effectiveness of our proposed algorithm and indicate the necessity of optimal power allocation.

Satellite array receivers must suppress interference whose spatial, spectral, and temporal characteristics vary across operating conditions, often with limited known symbols for adaptation. This paper studies when learned subspace augmentation is useful under finite pilot support. The receiver retains the instantaneous complex-linear receive subspace and adds a low-dimensional orthogonal complement generated from temporal and spectral features, with all basis coefficients estimated jointly from known symbols. A finite-sample analysis separates oracle representation gain from the additional pilot-to-payload estimation error caused by basis enlargement. Across 720 seen-family conditions, the proposed receiver achieves mean uncoded bit error rate (BER) 0.06521, versus 0.06572 for the receive-span ablation and 0.06719 for minimum-variance distortionless response; the 0.78% reduction relative to receive-span is modest and concentrated in spatially loaded narrowband regimes. A same-frame trained-versus-untrained comparison shows an average benefit from parameter optimization in the reference realization. Independent retraining from three initializations yields closely clustered held-out performance, while the selected model order varies between $L=1$ and $L=2$. For three unseen interference families, mean net augmentation gain is negative and aggregate MSE does not improve over receive-span. The results therefore identify a condition-dependent regime in which subspace augmentation is useful when representation gain exceeds finite-pilot estimation cost, rather than a broadly transferable advantage across interference types.

Enhancing user access capacity in satellite beam-hopping systems remains challenging due to dynamic traffic and limited beam dwell times. Conventional Multi-Frequency Time-Division Multiple Access (MF-TDMA) proves highly inefficient under such constraints. To overcome this, we propose a novel scheme that integrates power-domain Non-Orthogonal Multiple Access (NOMA) with MF-TDMA, employing Successive Interference Cancelation (SIC) for multi-user signal separation. A bi-directional adaptive carrier synchronization method and optimized burst structure are introduced, which collectively reduce synchronization overhead by over 40% compared to MF-TDMA. Simulations demonstrate a dramatically improved frame error rate of 0.0005% at 4 dB SNR—30 times lower than the 0.016% achieved by MF-TDMA—and a transmission efficiency of 92–97%, significantly outperforming conventional MF-TDMA. These results validate the proposed method’s substantial gains in capacity and efficiency for next-generation satellite systems.