Satellite networks have become central to the evolution of modern communications systems due to their potential for extensive global coverage. However, high latency in satellite systems poses critical challenges for delay-sensitive applications, underscoring the need for performance metrics that characterize ultra-reliable low-latency communications. To address these challenges, data-oriented approach, which is already widely studied in terrestrial networks, provides a fresh perspective by evaluating the transmission performance where it prioritizes both reliability and latency. This work introduces the data-oriented approach to uplink hybrid satellite-terrestrial networks (HSTNs), focusing on non-orthogonal multiple access (NOMA)-assisted semi-grant-free (SGF) transmission where terrestrial relays support the transmission between the satellite and users. Specifically, a novel grant-free user (GFU) admission protocol based on distributed contention control, the corresponding power allocation scheme for GFUs, and the relay selection procedure presented following the data-oriented approach. Then, the maximum number of GFUs that can be admitted under given data-oriented design requirements is determined. The analytical results are verified by extensive Monte-Carlo simulations, while a wide body of numerical results are also offered to understand and demonstrate the impacts of different system parameters. The proposed analytical framework offers useful insights toward the design of practical HSTNs, particularly in the context of delay-sensitive applications, by revealing the relationship between the amount of information data, the power consumption, and the satellite distance. The results demonstrate that the proposed scheme improves the DOR performance compared to conventional grant-free access and frequency division multiple access methods by dynamically selecting GFUs and allocating transmit power based on channel conditions. It is also shown that more GFUs can be admitted, especially with larger bandwidths and/or relaxed threshold settings.

Satellite networks have become central to advancing modern communication standards due to their potential for extensive global coverage. Despite this, high latency in satellite systems poses critical challenges for delay-sensitive applications, underscoring the need for reliable metrics that reflect ultra-reliable, low-latency communication. To address these challenges, data-oriented approaches, widely adopted in terrestrial networks, offer a fresh perspective by assessing transmission performance through delay outage rates. This work introduces the data-oriented approach to hybrid satellite-terrestrial networks (HSTNs), focusing on an uplink non-orthogonal multiple access (NOMA) scheme where grant-based and grant-free users coexist. The proposed analytical framework reveals the relationship between the amount of information data, power consumption, and the satellite distance, providing valuable pathway for optimizing the performance of HSTNs in the context of delay-sensitive applications.

As wireless systems move toward 6G, ensuring ultra-reliable low-latency communication (URLLC) securely is a key design challenge. Addressing the strict latency and reliability demands requires a shift in performance evaluation. The delay-outage rate (DOR) has recently emerged as a data-oriented metric that captures the probability of transmission time exceeding a threshold under ideal conditions. This work extends the data-oriented framework to include physical layer security, focusing on jamming and eavesdropping threats. We analyze how constant and random jamming affect DOR in the multi-antenna systems, highlighting the role of spatial and spectral resources in mitigation. Our analysis, supported by empirical simulations, offers new insights for designing secure, low-latency systems resilient to jamming—supporting robust ultra- or hyper-reliable low-latency communications in future 6G networks.

In this article, we study the timely notion of short-packet communications, with specific focus onuplink rate-splitting multiple access (RSMA) systems under the finite blocklength regime. Specifically, we consider rate-adaptive and power-adaptive uplink RSMA mechanisms, incorporating multiple user groups, and derive analytical expressions for the fundamentaldelay-outage rate (DOR)metric. The analytical derivations are validated through the corresponding Monte Carlo numerical simulations, reflecting high accuracy. Then, the derived DOR expressions are exploited for providing optimal DOR performance under diverse individual transmission parameters, such as different information delivery time thresholds, varying blocklengths and channel bandwidths, while also considering the non-orthogonal multiple access (NOMA) as a particular special case. Importantly, DOR optimization in terms of the message splitting ratio is also pursued, and a feasible optimization algorithm is proposed. A vast collection of numerical results is then provided, comparing between the rate-adaptive and the power-adaptive schemes, assessing the impact of message splitting ratio optimization while also comparing between RSMA and NOMA. Additionally, the overall power efficiency and impacts of imperfect channel state information (CSI) are assessed and shown. Overall, the offered analysis methods and numerical results provide valuable tools and insight for deploying, designing and optimizing data-oriented uplink RSMA mechanisms in future wireless systems such as the emerging 6G networks.

The so-called data-oriented approach has gathered significant attention in the context of short-packet communications in fifth-generation (5G) and beyond networks. Specifically, it introduces a transient performance metric for small data transmissions, where the amount of data and available bandwidth play crucial roles. Such data-oriented approach has recently been introduced in downlink rate-splitting multiple access (RSMA) system context, which represents a flexible and promising non-orthogonal multiple access paradigm. Building upon such prior-art, this paper introduces the data-oriented approach to uplink RSMA systems under the finite blocklength regime. Specifically, we consider rate-adaptive and power-adaptive uplink RSMA mechanisms, under the data-oriented approach, and derive analytical expressions for the delay-outage ratio (DOR) metric. The analytical derivations are validated through corresponding Monte Carlo numerical simulations. The numerical results show that the DOR performance is directly linked with the transmit antenna diversity, while being also dependent on the accuracy of the channel state information as well as on the power budget of the uplink users. The obtained results highlight the importance of the new data-oriented DOR metric for efficient design of the uplink RSMA mechanism in future networks.