Chapter 18

5G and beyond

Abstract

This chapter provides an outlook into mobile networks beyond 5G. Standardization activities and time plans for the evolution beyond 5G are described. The evolution of cellular IoT is discussed including the areas of massive IoT, critical IoT, broadband IoT and industrial IoT.

Keywords

5G; Beyond 5G; Cellular internet of things (CIoT); Internet of things (IoT); Long-term evolution (LTE); LTE-M; Machine-to-machine (M2M); low power wide-area (LPWA); Machine-type communications (MTC); Narrowband IoT (NB-IoT); Third generation partnership project (3GPP); Massive machine-type communications (mMTC); Massive IoT; Critical machine-type communications (cMTC); Critical IoT; Ultra-reliable and low latency communications (URLLC); Industrial IoT (IIoT)

1. References 

The mobile communication networks that have been specified by 3GPP until today, in April 2019, lay a solid foundation for cellular IoT, in addition to enhanced mobile broadband services required by a connected society. Long-Term Evolution (LTE) is, and will remain the dominating radio access technology globally in mobile networks for the many years to come, but a fast introduction of 5G networks based on the 5G New Radio access technology is foreseen reaching 1.5 billion subscriptions by 2024 [1]. These networks address a broad range of cellular Internet of Things (IoT) use cases and requirements, supporting massive IoT applications as well as critical IoT services. LTE-M and Narrowband IoT (NB-IoT) are the technology solutions for massive IoT in cellular networks, as described in Chapters 2, 5–8 and 16. LTE-M and NB-IoT can be well combined and integrated into both LTE and NR networks as shown in Chapters 5 and 7. For critical IoT both LTE and NR provide novel capabilities for ultra-reliable and low latency communication (URLLC) as described in Chapters 9–12 and 16. There is a high excitement about the possibilities that critical IoT will bring for new services that may affect many new market segments, like connected energy networks, industrial systems, etc. However, as the related standards have only recently been finished, no commercial deployments for critical IoT exist today; so far real deployments are limited to promising trial systems for technology validation. As LTE URLLC and NR URLLC become ready for market introduction at the same time, we foresee that NR will become the main technology for critical cellular IoT due to its higher flexibility and even better performance.

Based on this foundation the mobile network evolution will continue. In 3GPP the standardization evolves continuously in phases defined in standard releases. The specification phase for a 3GPP release lasts between 12 and 18 months and brings new features to the standard. Like this, the LTE mobile networks have evolved significantly from the original specification in 3GPP release 8 in 2008 up to the release 15 that was finalized in in mid-2018. In release 15, also the first 5G new radio systems were specified. Currently, the 3GPP standardization is working on its release 16, which will be ready by the end of 2019; and the definition of the next release 17 is in early preparation and is expected to last until the first half of 2021. After that, a continuous evolution in further releases continues.

For massive IoT the following evolution can be anticipated. 3GPP has agreed that an Machine-Type Communications transmission mode in NR that addresses low power wide-area (LPWA) massive IoT use cases is not planned in the first NR releases [2]. This IoT segment is already very well addressed by LTE-M and NB-IoT, and tight integration of LTE-M and NB-IoT into an NR carrier has already been ensured in standardization. Thus, the combination of NR with LTE-M and NB-IoT addresses the 5G needs for LPWA massive IoT. A unique NR-based massive IoT LPWA communication mode could only be motivated if significant improvements over LTE-M/NB-IoT could be achieved and a large market demand could be anticipated. Technical motivations could be, for example, to address new NR frequency bands or define an massive Machine-Type Communications mode which can exploit the full TDD flexibility of NR. We do not foresee that such an approach will become reality for several years to come. One segment, in which an evolution of cellular IoT capabilities is desirable, is the support for demanding sensors. Those can be sensor devices, that do not transmit only infrequently small amounts of data, but higher data volumes. Examples can be industrial sensors for advanced monitoring like machine vision or acoustic sensing. Other examples are sensors which transmit infrequently but require reliable low latency, like alarms. This category can be described by having higher requirements e.g. data rate, latency, reliability than the massive IoT category defined today, while at the same time still striving for cheap devices of low complexity and long battery operation. This category can be placed in the requirements triangle of Figure 1.4 in-between massive MTC, critical Machine-Type Communications and enhanced mobile broadband, and is described as broadband IoT in Ref. [3]. Such a category could leverage the design principles of NR, like the flexible numerology, the flexible TDD, the beam management, and address all NR frequency bands [4,5].

For critical cellular IoT services the foundation has been laid in release 15 for LTE and NR with the support of ultra-reliable and low latency communication (URLLC), which enables to transmit small messages over the radio access network with a latency not exceeding 1   ms and a reliability of 1-10 ⁻⁵. In release 16 further improvements for NR are developed, that increase the reliability level to 1-10 ⁻⁶ for even lower latency bounds of 0.5   ms [6], and provide better support for the multiplexing of URLLC traffic flows with different service requirements. Other standard efforts have the objective to make a NR critical IoT solution that better supports communication services of different vertical use cases. Many vertical use cases will introduce 5G as wireless communication solution into an existing communication system. For industrial communication as an example, there are already communication solutions based on fieldbus technologies and Ethernet. 5G would complement such solutions and need to integrate into the existing systems. NR release 16 specifies how the NR system can integrate into such an industrial local area network [7,10–12]. Furthermore, the 5G system shall be able to provide non-public networks, which are networks that are intended for non-public use and reserved to a defined set of devices. For example, if the 5G system is used for connecting devices for the monitoring and automation of the energy grid, the 5G system should provide a non-public network access to those devices. A similar situation exists for the devices monitoring and automation of industrial systems, like smart mines, smart harbors or smart factories; also those should be able to make use of a 5G non-public network. A non-public network can be setup in different means. It can either be a standalone non-public network, or a non-public network which is integrated into the public 5G network infrastructure. The latter can be realized by a logical separation of public and non-public network services, for example, by means of network slicing or network sharing, where it needs to be ensured that the usage of transmission resources of the non-public network services can be protected from access attempts of non-authorized devices. In order to increase the reliability and availability of the 5G system, also methods for redundant data transmissions are being specified in release 16 [8,9].

One part of the customization of 5G for vertical use cases is to interwork with relevant communication technologies in such areas. The most prominent wired communication technology for critical IoT communication is time-sensitive networking as extension of Ethernet. By bringing 5G communication into industrial communication systems, an interworking with time-sensitive networking is a pre-requisite. Work is ongoing in 3GPP to facilitate such interworking [7,9], which comprises time-sensitive communication schemes where the transmission latencies are loss-free, bounded and deterministic. Further, it must be possible to provide time-synchronization to one or more reference clocks, to devices over the communication system.

Extending 3GPP solutions for operation in unlicensed bands has always been a topic of interest. In release 16, 3GPP will introduce NR-based radio access to unlicensed spectrum. This feature is generally referred to as NR-U. Although the primary focus of NR-U in release 16 is enhanced mobile broadband use cases, we foresee that NR-U will be further enhanced beyond release 16 to also support IoT use cases.

There are several areas for longer-term evolution of 5G systems [14,15]. From a radio perspective, more spectrum may be addressed in a 5G evolution. This can go beyond the 52.6   GHz defined for 5G in release 16, all the way to 100   GHz and in the long run possibly even to Tera-Hertz spectrum. For the latter a re-evaluation of the fundamental radio access design may be required. Another area is to widen the topology options of a beyond 5G system. Integrated Access Backhaul is already investigated in standardization, where the same spectrum band is used for the backhaul connection of a base station and the access connection of the devices. This could be extended to multi-hop and mesh topologies. One motivation may be to provide extreme reliability by managing the inherent redundancy of mesh topologies, but also to provide efficient system coverage in very high spectrum bands with limited reach. Part of the flexible topology and increased reliability and efficiency can motivate the introduction of device-to-device communication with cooperative relaying. By cooperation, multiple devices can for example form a virtual antenna array. This could significantly extend the functionality of device-to-device communication schemes as defined for LTE. A side-effect of such schemes is that the sharp border in mobile networks between network and devices blurs, since devices can become network nodes toward other devices.

In the past few years there has been a growing interest in extending 3GPP's reach from the earth to the sky. LTE has been optimized to support drone communication since Release 15, and NR is expected to become equipped with similar capabilities. It the area of non-terrestrial networks 3GPP is currently studying the ability of NR to provide a unified non-terrestrial networks communications solution for satellite constellations in low earth orbits, medium earth orbits and geosynchronous orbits. This extension of NR has the potential of supporting use cases requiring coverage in areas where it is challenging to provide terrestrial network coverage [16].

Finally, the introduction of machine learning into communication systems is an area for future research [13]. In a first step, machine learning will play a role in optimization and configuration of the network and devices. The mobile network, as well as the devices comprise hundreds or even thousands of configurable parameters. Radio resource management algorithms are used for example for efficient allocation of radio resources, performing handovers and assigning devices to different frequency bands. The usage of machine-learning has potential to improve the network configuration and optimize radio resource management algorithms, in particular when multiple algorithms may interact. As a second step, 5G networks may be evolved to facilitate a broader application in machine learning. Machine learning essentially depends on the availability of data for training and analysis. A beyond 5G system could provide enhanced reporting mechanisms for supporting machine-learning based algorithms.

References

[1]. Ericsson. Ericsson mobility report. November 2018 Available at:. https://www.ericsson.com/en/mobility-report/reports/november-2018.

[2]. Ericsson. Interim conclusions on IoT for rel-16, RP-180581, 3GPP TSG RAN meeting #79, Chennai, India, March 19-22; 2018.

[3]. Ericsson. Cellular IoT evolution for industry digitalization. 2018 website, [Online]. Available at:. https://www.ericsson.com/en/white-papers/cellular-iot-evolution-for-industry-digitalization.

[4]. Ericsson. New SID on NR MTC for industrial sensors, RP-190432, 3GPP TSG RAN meeting #83, Shenzhen, China, March 18–21; 2019.

[5]. Ericsson. Motivation for new SID on NR MTC for industrial sensors, RP-190433, 3GPP TSG RAN meeting #83, Shenzhen, China, March 18–21; 2019.

[6]. Huawei, HiSilicon, Nokia, Nokia Shanghai Bell. New SID on physical layer enhancements for NR ultra-reliable and low latency communication (URLLC), RP-182089, 3GPP TSG RAN meeting #81, Gold Coast, Australia, September 10–13; 2018.

[7]. Third Generation Partnership Project. New WID: 5GS enhanced support of vertical and LAN services, SP-181120, 3GPP TSG SA meeting #82, Sorrento, Italy, December 12–14; 2018.

[8]. Third Generation Partnership Project. New WID on enhancement of ultra-reliable low-latency communication support in the 5G core network, SP-181122, 3GPP TSG SA meeting #82, Sorrento, Italy, December 12–14; 2018.

[9]. Nokia, Nokia Shanghai Bell. New WID: support of NR industrial internet of things (IoT), RP-190728, 3GPP TSG RAN meeting #83, Shenzhen, China, March 18-21; 2019. .

[10]. 5G Alliance for Connected Industries and Automation (5G-ACIA). 5G non-public networks for industrial scenarios, white paper. March 2019 Available at:. https://www.5g-acia.org/index.php?id=6958.

[11]. 5G Alliance for Connected Industries and Automation (5G-ACIA). 5G for Automation in Industry - primary use cases, functions and service requirements, white paper. March 2019 Available at:. https://www.5g-acia.org/index.php?id=6960.

[12]. 5G Alliance for Connected Industries and Automation (5G-ACIA). 5G for connected industries and automation - second edition, white paper. February 2019 Available at:. https://www.5g-acia.org/index.php?id=5125.

[13]. Dahlman E, Parkvall S, Peisa J, Tullberg H, Murai H, Fujioka M. Artificial intelligence in future evolution of mobile communication. In:  2019 international conference on artificial intelligence in information and communication (ICAIIC), Okinawa, Japan . 2019 Available at:. http://doi.org/10.1109/ICAIIC.2019.8669012.

[14]. Dahlman E, Parkvall S, Peisa J, Tullberg H, Murai H, Fujioka M. Future evolution of mobile communication. In:  IEICE general conference, Tokyo, Japan, March 19–22 . 2019.

[15]. Dahlman E, Parkvall S, Peisa J, Torsner J, Tullberg H. Wireless access evolution. In:  6G wireless Summit, Levi, Lapland, Finland, March 24–26 . 2019.

[16]. Third Generation Partnership Project. New Study item: Study on solutions evaluation for NR to support non-terrestrial network, RP-181370, 3GPP TSG RAN meeting #80, La Jolla, USA; 2018.