Next-Generation Wireless Networks: Forged in Resilience, Fueled by Sustainability
By Walid Saad, Rolls Royce Commonwealth Professor of Electrical and Computer Engineering, Virginia Tech
Wireless cellular networks are the backbone of modern society. Without broadband and pervasive communication, many essential services — ranging from critical infrastructure to everyday mobile interactions — would not be possible. The evolution of wireless cellular networks, from their early commercial launch in the 1980s to today’s fifth generation (5G) and the anticipated sixth generation (6G) networks, has been driven by the need to provide higher data rates, progressing from a few kilobits per second (kbps) to around 10 Gigabits per second (Gbps) for 5G, with an expected 100 Gbps for 6G. However, with the emergence of novel wireless services like AI-powered connected autonomy (e.g., autonomous robotics, self-driving cars, drones, AI agents, etc.), Industry 5.0, and immersive reality, throughput alone may no longer be the primary quality-of-service (QoS) priority for next-generation wireless systems, including 6G. Some even argue that advances in multi-antenna systems and other capacity-focused technologies have made achieving high throughput less challenging than before. This shift is reflected in the rise of ultra-reliable low-latency communications (URLLC) during the 5G era, designed to support Internet of Things (IoT) applications that prioritize reliability over throughput. These applications require highly reliable communication links capable of maintaining extremely low latency, in the sub-millisecond range. Despite the promise of URLLC, real-world deployment has faced significant challenges, including guaranteeing high reliability in the face of the wireless environment dynamics and addressing the economic complexities of offering these services at scale. As the focus shifts away from increasing throughput and minimizing latency, the big question for the next evolution of wireless systems, including 6G, will be: What are the key performance indicators (KPIs) that will truly drive these networks forward? The answer lies in resilience and sustainability.
Resilience is a fundamental concept, originally rooted in ecology, psychology, and environmental studies. It refers to a system’s ability to withstand disruptions, adapt to changing conditions, and recover swiftly, ensuring continued functionality amid unforeseen challenges. Resilience extends beyond traditional reliability, which aims to prevent failures, and robustness, which ensures performance under expected disturbances. In 5G, resilience was closely linked to security and trustworthiness in the face of vulnerabilities. In next-generation wireless systems like 6G, resilience must evolve beyond this rudimentary definition into an inherent network feature. It should enable cross-layer protocols and system-level frameworks to detect, absorb, and recover from disruptions, whether unintentional (e.g., failures, changes in wireless dynamics) or intentional (e.g., cyberattacks). Unlike reliability and robustness, which solely focus, respectively, on long-term and short-term objectives, resilience enables a network to address both through two key phases: absorption, where the network attempts to maintain its functionality in face of disruptions, and remediation (also called adaptation), during which it will execute strategies to adapt its operation and restore QoS. By adapting over time and learning from experienced disruptions, a resilient network can evolve to handle disruptions more effectively, maintaining service continuity and reducing the impact of adverse wireless conditions on its users. This design shift is already reflected in the ITU’s inclusion of resilience as a key principle for 6G. Furthermore, the emergence of complex network architectures, like non-terrestrial networks (NTNs) and high-frequency communications in the terahertz and millimeter wave bands, reinforces the need for resilience. To this end, a resilient-by-design approach must be embedded in a wireless system’s architecture, functions, and protocols from the outset, rather than relying on ad hoc solutions. Achieving this vision requires overcoming technical, architectural, and operational challenges. First, defining rigorous resilience metrics is key, incorporating both end-to-end and cross-layer perspectives. While resilience metrics for engineering domains like cyber-physical systems exist, they cannot be directly applied to wireless networks. Instead, concepts from economics and risk analysis can provide a valuable tool for defining wireless-centric resilience measures. Second, developing effective strategies for absorption and remediation is another significant challenge. Although artificial intelligence (AI) holds promise in designing such strategies, today’s deep neural networks are not suitable due to high training overhead and lack of performance guarantees. New AI techniques, such as those based on symbolic reasoning or category theory, may offer stronger foundations for adaptive decision-making. Third, building resilience into both network protocols and AI components is a major challenge for AI-native 6G systems. An end-to-end resilient-by-design framework will be essential to ensure the network and its AI components can jointly withstand disruptions. Finally, there is an important need to develop rapid recovery algorithms that can minimize time-to-recovery from diverse uncertainties and disruptions.
The wireless sector may make major strides in building a more sustainable future by utilizing AI-native systems, integrating intelligent protocol and resource management designs, and utilizing efficient hardware designs and renewable energy.
While resilience-by-design will form the backbone of future wireless networks, sustainability will drive their evolution as well. Sustainability refers to a system’s capacity to operate efficiently over the long term while minimizing environmental impact, conserving resources, and promoting economic and social well-being. Clearly, designing sustainable wireless networks requires considering multiple dimensions beyond the classical metric of energy efficiency. While energy efficiency was a key focus in the wireless evolution toward 6G, achieving sustainability in practice still presents a major hurdle. For example, though 5G is 90% more efficient than 4G in terms of data bits per kilowatt, the anticipated increase in density and traffic could lead to net energy consumption 4 to 5 times higher, with radio access network (RAN) components being a major contributor. Therefore, even from an energy efficiency standpoint, sustainability remains elusive. Sustainability can be divided into two types: operational and embodied. Operational sustainability focuses on energy consumption, emissions, resource utilization, and environmental impact during active network operation. Embodied sustainability refers to the environmental impact throughout the network’s lifecycle, including production, manufacturing, and disposal. Several measures must be integrated into next-generation wireless networks to ensure operational sustainability. For instance, there is a need to design intelligent algorithms that can dynamically allocate system resources (e.g., energy, spectrum, data) based on both QoS needs and sustainability goals. Techniques like semantic communications, where AI algorithms are used to minimize data transmission by extracting minimalistic data structures, could further reduce resource consumption in wireless RANs. The network’s carbon footprint can also be decreased by utilizing efficient cooling systems and renewable energy sources. For AI-native networks, operational sustainability must also apply to the AI algorithms themselves, calling for novel low-complexity AI architectures that reduce computing power. Generalizable AI systems that operate with minimal training and process unknown datasets will also contribute to sustainability by cutting down on retraining and reducing energy consumption both on-device and at data centers. Moreover, developing open and unified RANs that can work across heterogeneous systems, such as NTNs, will enhance resource efficiency and long-term sustainability. For embodied sustainability, energy-efficient hardware, such as antenna arrays for high-frequency bands, can reduce environmental impact. Modular, reusable hardware designs and software patching also help reduce electronic waste. The development of such solutions will contribute to more sustainable network design, minimizing both operational and embodied impacts throughout the network lifecycle.
As wireless networks evolve toward 6G and beyond, the dual focus on resilience and sustainability will be crucial for addressing performance and environmental challenges. The transition from a throughput-centric model to one that emphasizes resilience, ensuring networks can absorb and recover from disruptions, will enable systems to maintain continuous service in dynamic and unpredictable environments. This will help support wireless services like connected autonomy and immersive reality, as well as new architectures like NTNs. Sustainability, encompassing both operational and embodied aspects, will be integral to the long-term viability of wireless networks. Operational sustainability must focus on energy efficiency, emission reduction, and resource utilization during active operation, while embodied sustainability focuses on environmental impact across the entire lifecycle of network hardware and processes. The wireless sector may make major strides in building a more sustainable future by utilizing AI-native systems, integrating intelligent protocol and resource management designs, and utilizing efficient hardware designs and renewable energy. Achieving these goals will not be without challenges, but by embracing a resilient and sustainable approach to network design, the future of wireless technology will be forged in resilience and fueled by sustainability, powering a connected world while minimizing its environmental impact.