Ayman Elnashar
Convolutional neural receivers such as DeepRx outperform minimum mean-square error physical uplink shared channel detection on in distribution channel and waveform configurations, but their behavior under calibration drift when transmitter or channel parameters depart from the training envelope is poorly characterized.
Shimaa Naser, Maryam Tariq, Raneem Abdel-Rahim et al.
Direct handset-to-satellite (DHTS) communication is emerging as a core capability of 6G non-terrestrial networks, enabling standard devices to directly access low Earth orbit (LEO) satellites. While LEO provides the physical access layer for DHTS, large-scale device connectivity introduces challenges in mobility management, interference control, spectrum efficiency, and constellation-wide coordination. Relay-only LEO architectures are insufficient to manage massive handset access under dynamic traffic and energy constraints. This article introduces a hierarchical architecture in which direct handset-to-LEO access is supported by multi-orbit space-based data centers (SBDCs) spanning LEO, medium Earth orbit (MEO), and geostationary Earth orbit (GEO). In this framework, LEO satellites handle radio access and real-time inference, while higher orbital layers provide regional aggregation, global orchestration, and compute-aware routing. By embedding distributed in-orbit computing, energy-aware scheduling, and AI-driven hierarchical control, the constellation evolves from a passive relay network into an intelligent multi-layer system capable of supporting large-scale DHTS services. We discuss key enabling technologies, envisioned multi-orbit integrated Earth-space compute architecture, and open research challenges in integrating multi-orbit computing, highlighting pathways toward scalable and resilient 6G DHTS networks.
Ayman Elnashar, Mohamed A. El-Saidny, Mohamed Yehia
Voice over Long-Term Evolution (VoLTE) has been witnessing a rapid deployment by network carriers worldwide. During the phases of VoLTE deployments, carriers would typically face challenges in understanding the factors affecting the VoLTE performance and then optimizing it to meet or exceed the performance of the legacy circuit switched (CS) network (i.e., 2G/3G). The main challenge of VoLTE service quality is the LTE network optimization and the performance aspects of the service in different LTE deployment scenarios. In this paper, we present a detailed practical performance analysis of VoLTE based on commercially deployed 3GPP Release-10 LTE networks. The analysis evaluates VoLTE performance in terms of real-time transport protocol (RTP) error rate, RTP jitter and delays, block error rate (BLER) in different radio conditions and VoLTE voice quality in terms of mean opinion score (MOS). In addition, the paper evaluates key VoLTE features such as RObust Header Compression (ROHC) and transmission time interval (TTI) bundling. This paper provides guidelines for best practices of VoLTE deployment as well as practical performance evaluation based on field measurement data from commercial LTE networks.