Multicast/Broadcast Services in 6G Wireless
Point-To-Multipoint (PTM), also referred as multicast/broadcast delivery is considered as a suitable transport mechanism for simultaneously delivering the same content to multiple devices within the covered area with a defined quality of service (QoS). While 5G presents trade-offs on latency, energy, costs, hardware complexity, throughput, and end-to-end reliability addressing the requirements of mobile broadband and ultra-reliable, low-latency communications by different configurations of 5G networks, 6G, on the contrary, will be developed to jointly meet stringent network demands in terms of ultra-high reliability, capacity, efficiency, and low latency required by the use cases envisaged for the incoming decade.
The 4G systems unlocked the potential of video-over-wireless for Augmented Reality (AR) and Virtual Reality (VR), and the 5G adoption of new mmWaves spectrum will trigger the early adoption of AR/VR. However, it is likely that the proliferation of AR/VR applications will drain the 5G spectrum, just like video-over-wireless did with 4G networks, pushing system capacity requirements for 6G far beyond to the 20 Gbps target defined for 5G.
Moreover, pervasive connectivity will be a target of 6G due to the extensive growth in the number of Internet-of-Things (IoT) devices which will realize advanced services such as smart traffic, environment monitoring, virtual navigation, telemedicine, digital sensing, high definition (HD), and UHD video transmission in connected drones and robots with also integration of non-terrestrial access such as LEO satellite constellations. Meanwhile, IoT have become a prevalent system in which people, processes, data, and things connect to the Internet and each other. Globally, M2M connections will grow 2.4-fold, from 6.1 billion in 2018 to 14.7 billion by 2023, and therefore, it is very challenging for the existing multiple access techniques to accommodate such a massive number of devices.
Moreover, 6G networks will require a higher overall energy efficiency (10-100x with respect to 5G), to enable scalable, low-cost deployments, with low environmental impact, and better coverage. The support of PTM from the initial 6G design stages is therefore especially needed to address requirements of the forthcoming IoT deployments such as massive software updates, or multimedia data acquisition also beyond AR/VR, rising severe communication challenges in 6G networks. For instance, for Teleportation the datarate requirements of a 3D holographic display a raw color hologram, full parallax, and 30 fps, would require 4.32 Tbps.
On the other hand, in current cellular IoT systems, the devices are still monitoring service announcements, even though firmware/software updates are rare. In that sense, novel on-demand paging methods would allow 6G IoT devices not to monitor service announcements but instead to be paged to receive multicast data, reducing energy consumption. In this framework, while evolved Multimedia Broadcast Multicast Services (eMBMS) [model defined by the 3rd Generation Partnership Project (3GPP) can be considered as a successful trend in 4G LTE for applications such as video-on-demand, further evolved Multimedia Broadcast Multicast Services (feMBMS) has not gained similar popularity in 5G because of its inefficiency in terms of resource utilization and energy consumption. However, some improvements have been proposed in literature to overcome the above limitations of feMBMS, which could enable efficient multicast transmission in 6G. The research at Net4U lab is investigating novel hybrid unicast-multicast techniques based on dynamic sub grouping and non-orthogonal multiple access.
Dynamic access and balancing for differentiated traffic demand over 6G networks
The huge increase in the data traffic, billions of connected devices, and the development of critical services with high data rate and ultra-reliable low latency require flexibility, scalability and availability. To manage these diverse traffic demands, the network slicing concept is crucial, dividing the physical network into several logical networks with specific functionality and performance requirements.
The sixt generation (6G) of mobile broadband communication systems will include a diversity of traffic demands and tight QoS requirements. This situation, jointly to billions of connected smart devices, heterogeneous network environment, and the “always best connected” (ABC) vision, constitutes a significant challenge.
According to the Cisco forecast, the Wi-Fi and mobile devices will account for 71 percent of IP traffic by 2022. Moreover, applications like 4K/8K ultra-high-definition video (UHD VI), virtual/augmented reality (VR/AR), cloud gaming (GM), and Internet of Things (IoT), are characterized by different Key Performance Indicators (KPIs), making more complex the management and exploitation of network resources.
In this cumbersome scenario, network slicing (NS) is a crucial concept to introduce flexibility, isolation and accommodate several services and requirements. On the other hand, Software-Defined Network (SDN) and Network Function Virtualization (NFV) play critical roles and complement the network slicing paradigm in future 6G systems.
In heterogeneous networks, user equipment (UE) should be associated with one or more NS via a macrocell, small-cell, or Wi-Fi access point (AP). The selection of the best combination of the radio access network (RAN) and NSs is a necessary and challenging task to optimize resource utilization and improve user’s satisfaction. The research at Net4U lab focuses on dynamic access control and NS allocation strategies to select the most efficient combination of the access network and NSs over 6G networks.