If 5G is to support infinite variety, it needs diversity in the standards process
Just as 5G is charged with supporting a far wider variety of use cases and services than 4G, so its platforms need to be more diverse in their capabilities, and that means broadening the ecosystem right from the starting point in the standards work. Increasingly, developments that are taking place in adjacent sectors such as WiFi, cable or satellite will influence, or be directly incorporated into, official 5G platforms.
Examples spotted just in the past week include initiatives in the 60 GHz unlicensed band, which have relevance to 5G millimeter wave; a new CableLabs technology which could help solve ultra-low latency challenges in wireless; and work on deploying 5G over satellite, rather than treating radio and satellite as perennial enemies as they battle over spectrum.
Such developments need to be welcomed and embraced by 3GPP processes and by vendors and operators. Hopes for greater cooperation and convergence between cellular and WiFi in the 5G platform were largely dashed, although in reality, developments like WiFi 6 and the 60 GHz 802.11ay will find their role in pragmatic multi-network implementations by cellular and alternative operators.
But the 5G, and future 6G, platforms would benefit more if expertise and innovation were pooled from the start, rather than shoehorned in later. Bodies like CableLabs are getting more and more involved in cellular standards as the lines between wireless and wireline, and even terrestrial and satellite, blur. What is needed for 5G to achieve its aims is a huge, unified pool of capacity which can be harnessed dynamically for any use case. This dream will be best realized with a great deal more cooperation between different R&D and standards camps.
Terragraph and 60 GHz are infiltrating the 5G camp
The US operators’ decision to use millimeter wave spectrum for their first 5G deployments may have been forced on them by their lack of virgin C-band airwaves, but it has driven a great deal of innovation into the high frequency bands. However, most operators outside the USA see mmWave capacity, coupled with sub-GHz spectrum coverage, as a second or third phase in their 5G journey – for now, the 3.5 GHz band has plenty of capacity for deploying 5G hotspots while LTE provides the coverage.
When they do come to adopt mmWave, their US counterparts – and a few others, for instance in South Korea – will have done them the favor of driving forward a device ecosystem and some robust technology. But there are still challenges regarding propagation, indoor penetration, and risk of interference in the dense architectures that these low-range bands can support.
Many of the challenges are actually being addressed first in the 60 GHz band, the first mmWave spectrum to be commercially used for wireless broadband, but for a WiFi-like technology, WiGig, not for 5G. The ready availability of this spectrum, which is unlicensed in most countries, makes it a good target for R&D and for devices.
The latest example comes from IMDEA Networks Institute, one of nine R&D groups set up by the Spanish government in different branches of research from food to nanotechnology. The Networks Institute aims to improve network algorithms and protocols to support new architectures and operational models. It claims a major breakthrough with its new conceptual architecture, known as Searchlight.
This, according to team leader Professor Joerg Widmer, will enable hyperdense, but highly scalable networks in the 60 GHz band, and potentially other mmWave bands in future.
They have designed a means of aligning directional mmWave antennas rapidly in very dense deployments. Widmer claims the breakthrough is analogous to “the evolution of wired Ethernet from a shared medium to a fully switched network”. In wireless, he said, “we envision that future wireless networks will consist of many highly directional LOS (line of sight) channels for communication between access points and end devices”.
Searchlight uses angle information to align the antennas in order to deal with extremely dynamic radio environments where channels may appear and disappear over very short time intervals. Widmer said: “The architecture integrates a location system and learns a map of the radio environment, which allows us to rapidly select the most suitable access point and antenna beam pattern and allocate radio resource using predicted location as context information. Access points are deployed ubiquitously to provide continuous connectivity even in face of mobility and blockage and the project developed very low overhead network management mechanisms to cope with the high device density.”
IMDEA sees its work as part of a far larger, industry-wide effort to make communications more ubiquitous and affordable by harnessing plentiful resources in the millimeter wave bands and by using novel approaches to base station and antenna design. It believes the scalability results of its work will be very applicable to others’ mmWave deployments in future.
Widmer gave the examples of Google Loon, whose high altitude balloons have mmWave links, and Facebook’s Terragraph, which can bring connectivity to areas with limited physical infrastructure including towers or backhaul. mmWave “also has extremely interesting properties for large scale networks of small satellites to provide worldwide connectivity, such as the planned Starlink network of SpaceX and PointView Tech (Facebook), and is very likely to be used in such networks”.
Facebook’s Terragraph design, which it contributed to the Telecom Infra Project (TIP), is gaining a prominent place in the 60 GHz ecosystem, where it is heavily supported by Intel and others as a way to bring broadband wireless to underserved areas (and, for Intel, is the latest in a long line of non-3GPP technologies which it can support as a counterweight to a cellular network in which it has not played a major role).
Widmer thinks it is exciting for bringing economies of scale, and deployability, to 60 GHz because it uses a mesh of reconfigurable mmWave links to provide Internet access in urban and suburban environments.
Any developments which bring mmWave into the mainstream will be welcome to the survivors of a large group of start-ups which developed mmWave backhaul products in the mid-2000s, hoping to target an explosion in outdoor small cells which largely failed to materialize. Now that densification is happening – and will be driven further by mmWave access networks – those still standing may find a second wind and Terragraph reference designs may help them reduce costs and achieve scale.
For instance, Siklu, which develops backhaul and fronthaul equipment in the 60 GHz, 70 GHz and 80 GHz bands, recently said that its third generation Multihaul product line will incorporate Facebook’s Terragraph technology.
One of the challenges in mmWave bands is the size of the antennas, since these high frequencies are often used close to street level for access or small cell backhaul and fronthaul. Nokia recently asked the FCC to change US rules on antenna gain in the E-band (70/80 GHz) to allow for smaller, less obtrustive antennas which would make the spectrum more usable for backhaul in dense city networks.
Specifically, Nokia is asking the regulator to amend its microwave rules to reduce the minimum antenna gain from 43 dBi to 38 dBi, which would allow for deploying lower gain antennas where the use case demands it, while retaining the discretion to deploy higher gain antennas where applicable. It argued that 38 dBi gain is necessary for street level applications to reduce visual impact and weight/space constraints on street furniture.
The Fixed Wireless Communications Coalition (FWCC) has been asking for similar changes since 2012, pointing out in a 2018 submission that the rise in data traffic means small cells will require either fiber or point-to-point microwave backhaul, and in some environments only wireless is possible.
“For emerging small cell backhaul applications, including the necessarily small cells for 5G services, 70/80 GHz is often the best choice,” the FWCC said. “The very high available radio bandwidth—up to 10 GHz total—can manage needed data loads, while the high directivity and space attenuation simplify designs for frequency reuse.”
The 5G Americas group last month added its voice to the calls, saying service providers need greater flexibility to decide on size based on use case. And T-Mobile USA has argued that the E-Band is ideally suited for LTE and 5G backhaul because it is lightly licensed in the USA, and there is a full 10 GHz of available spectrum. It told the FCC last year that it had conducted extensive tests with backhaul supplier Ceragon Networks to show how current E-Band antenna rules are poorly suited to supporting the extensive antenna deployments needed for expanding LTE and 5G networks.
CableLabs says its sub-millisecond latency specs will apply to wireless
CableLabs, the standards and technology arm of the US cable industry, has been increasingly active in 5G efforts as its members look to expand their wireless networks and even invest in 5G spectrum. And some of the its developments, though initially targeted at cable networks, will become applicable to wireless and could drive deeper commonality across access networks.
This will be important to operators which see the 5G era as one in which fiber and wireless converge. This is not just about fixed/mobile services and hand-off, but a common core for all access technologies, and the ability to route traffic dynamically across wired and wireless connections depending on use case requirements and network conditions.
Some of the technologies which are being tested as possible important elements of 5G were first developed in the cable environment. These include full duplex (in which transmit and receive can take place on the same channel, doubling spectral efficiency).
Another example may prove to be low latency DOCSIS, final specs for which were recently released by CableLabs as an annex to its DOCSIS 3.1 standards. These support round trip response rates of one millisecond. Although low-latency DOCSIS is initially targeted at the cablecos’ HFC (hybrid fiber-coax) networks, CableLabs stressed that it will also be applicable to many access technologies, including FTTP (fiber-to-the-premise) and wireless.
In fact, this goes for most of the technologies included in the cable industry’s ‘10G’ programme, led by CableLabs, Cable Europe and Internet & Television Association, which sets out the roadmap for next generation networks, starting from 2020. It seeks to support speeds at least 10 times faster than current top end cable networks, as well as many other new capabilities – ambitions which CableLabs is clear will require multiple technologies used in unison.
The 10G technologies include:
- 25G-PON and 50G-PON (passive optical network fiber standards)
- FDX (full duplex)
- Point-to-point coherent optics
- DOCSIS 3.1, the latest release of the cable standard, along with FDX DOCSIS and low latency DOCSIS
- Various WiFi technologies, namely WiFi Easy Mesh, Passpoint, Vantage and WiFi PNM (proactive network maintenance)
- Low latency mobile backhaul.
The low latency DOCSIS 3.1 standard will be supported by existing DOCSIS 3.1 equipment with a software upgrade and is particularly targeting virtual reality gaming, also an application beloved of 5G supporters. Indeed, one European operator recently confided that it had separate departments developing business cases for 5G and for FTTP, which found themselves competing over the same target revenue stream, VR gaming.
“Although VR is still struggling to gain widespread adoption, that low and reliable DOCSIS latency will be a boon to gamers in the short term and will enable split renderings of VR and augmented reality (AR) in the longer term,” wrote Steve Glennon, distinguished technologist of the Advanced Technology Group at CableLabs, in a recent blog post.
One US cableco, Cox Communications is already testing a low latency gaming service for PCs in Arizona that costs an extra $14.99 per month, and 5G operators are considering similar propositions to boost wireless revenue (though in mobile environments, AR will be more relevant).
CableLabs said it had worked on optimization of traffic flows in order to give latency-sensitive applications a higher priority without slowing down other traffic. That started with DOCSIS 3.1’s Active Queue Management (AQM) feature, which reduces latency, but the new specs aim to take the capability to a new level.
Sat5G group boasts multiple use cases for integrated satellite/5G
In the run-up to 5G, and to this year’s World Radio Conference, the satellite and mobile industries are often portrayed as being at loggerheads. Their competing claims for mid-band spectrum, and satellite accusations that regulators favor terrestrial mobile unfairly, are real, but so is the potential for the two communities to work together more effectively on converged platforms.
An example of such work come from the SaT5G Consortium, a group of satellite communications operators, MNOs and cellular researchers, which conducted six demonstrations at the recent European Conference on Networks and Communications (EuCNC 2019) in Valencia, Spain.
These demoes focused on 5G-over-satellite use cases including video streaming, content caching, airline connectivity and backhaul.
The SaT5G project was launched in 2017 with funding from the European Union’s Horizon 2020 program, with the goal of developing plug-and-play satcom systems for 5G. The consortium includes 16 participants from nine EU countries plus Israel.
“SaT5G is about integrating satellite links with heavy emphasis on standardization to allow trusted operations and to facilitate industry adoption,” said Mike Fitch, technical manager of SaT5 – and also a professor at the UK’s Surrey University, known for its satellite expertise and for housing the country’s 5G Innovation Center (5GIC).
He added: “The focus is on eMBB to fixed and mobile networks, including support for orchestration and slicing, with the satellite links providing backhaul connectivity either alone or in parallel (multilink) connectivity with terrestrial links.”
The six demoes focused on many areas considered important to future 5G use cases, including edge computing, in-flight connectivity and access for users in highly dense stadium environment.
- One of the demonstrations in Valencia focused on edge computing, with layered 4K video streaming over a 5G multilink satellite/terrestrial network. The trial used an Avanti HYLAS 4 GEO satellite, VT iDirect’s 5G-enabled satellite hub and terminals, and the University of Surrey’s 5GIC testbed network.
- The same three organizations also participated in a demo of over-the-air multicast over satellite video for caching and live content delivery, using Broadpeak’s content delivery network (CDN).
- In the airplane connectivity demo, SES’s O3b medium earth orbit (MEO) satellite constellation was used along with Gilat Satellite Networks’ Taurus VSAT unit and virtualized satellite hub, to demonstrate virtualized services for content distribution to planes over a combined satellite and terrestrial 5G network. The demo also used Zodiac Inflight Innovations’ virtualized A320 plane cabin mock-up and connectivity infrastructure, Broadpeak’s CDN, and i2CAT’s terrestrial satellite resource coordinator.
- There were also two showcases of hybrid satellite/5G backhaul networks. One was a demonstration of local edge computing content caching using an established satellite and terrestrial backhaul link, with User Plane Function (UPF) situated at the edge node for content delivery. The UPF was able to handle requests for the local content by selecting between satellite or terrestrial links depending on network characteristics such as available capacity, network policy and link performance. TNO, who conducted the demo, used a satellite emulator testbed.
- In the second demo, transport supplier Ekinops showed hybrid 5G backhauling for extending services in rural markets and big venue events. It used multipath protocols and combined satellite/terrestrial link bandwidths for fast upload and download traffic and terrestrial link low latency for interactive traffic.
- Finally, Finland’s University of Oulu highlighted 5G NR over satellite networks in a video demonstration at the event with Thales Alenia Space. The two companies showed the possibility of applying 5G NR over satellite links.