5G Small Cells at Home

Last year, NGMN published a whitepaper on '5G Small Cells at Home'. The whitepaper is available here. The summary on the website states:

The first objective of this white paper is to explore the potential technologies that could help improve the performance of local connectivity at home.

In addition to this, the second objective is to look for solutions of radio resources management at home that would be controlled by the network. The current situation is that the local connectivity is selected by a connectivity manager embedded in the operating system of smartphones that may not have a complete view of what happens, for instance in terms of traffic on cellular networks.

The global objective for operators is then to keep home users connected wirelessly to their local – fixed access network based – connectivity (delivered e.g. by Wi-Fi, a “small cell at home”) with a “premium” quality of service instead of adding pressure on the Radio Access part of the mobile macro network. Challenges for mobile macro networks are for example a lack of (licensed) spectrum that can cover efficiently indoors from outdoor macro network (e.g. low bands spectrum), cost of the radio sites, incl. equipment.

The abstract from the whitepaper as follows:

It is observed that traffic offload - from cellular networks to indoor local Wi-Fi connectivity - takes place when users are at home, but tends to decrease, due to increasing cellular data volumes and due to sometimes better user experience (coverage, throughputs) offered by 4G compared to Wi-Fi 5 (mainly available today at home).

In order to reverse the current trend, this white paper proposes to consider 5G New Radio- Unlicensed (NR-U) technology (that will be part of the future 3GPP Release 16 – Dec. 2019) as a potential (additional) candidate for future small cells deployed at home.

It is expected that small cells at home using NR-U technology will provide – at least – radio performance as good as what Wi-Fi 6 could do, will enable the optimization of the management of radio resources as NR-U could be connected to operators’ core network. Furthermore, the deployment of small cells at home can ensure that the traffic generated at home will be transported via the fixed network, regardless if the Wi-Fi interface of the device is switched on or off.

It's available here.

Related Posts:

• The 3G4G Blog: 5G and Fixed-Mobile Convergence (FMC)
• The 3G4G Blog: Introduction to 5G ATSSS - Access Traffic Steering, Switching and Splitting
• The 3G4G Blog: Exploring Network Convergence of Mobile, Broadband and Wi-Fi
• Operator Watch Blog: BT's Converged Core to Launch in 2023
• 3G4G Small Cells Blog: Malaysia Looks at Small Cells for 5G
• 3G4G Small Cells Blog: 5G CrowdCell: World's First 5G OpenRAN Small Cell
• 3G4G Small Cells Blog: SK Telecom's In-building 5G NR Repeaters and 'Layer Splitter'

Small Cell Forum Releases 5G FAPI API Specifications

SCF has announced the release of 5G FAPI: PHY API Specifications. In the press release titled 'Small Cell Forum Publishes Specification to Drive Unified 5G Open RAN', SCF announced:

5G FAPI Release provides common APIs to support interoperability between 5G small cell hardware components and software layers enabling interoperability and preventing fragmentation.

Small Cell Forum (SCF), the telecoms organization making mobile infrastructure solutions available to all, has published the PHY API for 5G to stimulate a competitive ecosystem for vendors of 5G small cell hardware, software and equipment. The PHY API provides an open and interoperable interface between the physical layer and the MAC layer. 3G and LTE versions are already used in most small cells today.

The specification has been developed through a successful collaboration of companies from across the small cell eco-system, including; Intel, Qualcomm Technologies, Inc., Airspan Networks and Picocom Technology.

5G FAPI is an initiative within the small cell industry to encourage competition and innovation among suppliers of platform hardware, platform software and application software by providing a common API around which suppliers of each component can compete. By doing this, SCF provides an interchangeability of parts ensuring that the system vendors can take advantage of the latest innovations in silicon and software with minimum barriers to entry, and the least amount of custom re-engineering.

Operators are looking for a radically different cost model for 5G networks, one that relies on interoperability and an open, competitive ecosystem. As networks are disaggregated, a critical interface is the fronthaul between a distributed unit (DU) for radio functions and a centralised unit (CU) for protocol stacks and baseband functions. Open specifications such as SCF’s FAPI will enable operators to mix and match protocol stacks, basebands and radios from different vendors, and realize the benefits of deploying disaggregated, virtualized RAN (vRAN) networks.

The Forum also maintains the widely adopted FAPI specifications for 3G and LTE, as well as networked FAPI (nFAPI) for LTE supporting a MAC/PHY functional split, a key enabler for virtualisation of higher layer base station functions. In 5G this split point was also identified by 3GPP and called split option 6.

The Forum’s motivation for defining nFAPI in LTE was to establish a scalable ecosystem with a converged approach to virtualization across multiple suppliers, and the continued adoption of NFV/SDN make this is even more crucial for 5G. As such, the Forum plans to expand 5G FAPI to operate across split option 6 as 5G nFAPI.

A video of presentation by Clare Somerville, Intel & 5G FAPI lead from Small Cells World is embedded below:


In an interview in The Mobile Network last December, Prabhakar Chitrapu, who chairs SCF’s TECH Group said:

“Split RAN/Small Cell architectures have seven options, as identified by 3GPP. Of these, 3GPP has focused on Option-2 (RLC-PDCP) and ORAN on Option-7.2 (PHY-PHY). Option-6 (PHY-MAC) is not being addressed by any of these organisations. SCF seeks to fill this gap.”

“The PHY-MAC interface is important for the industry because it is an interface that has been highly successful in the 4G world, where it is called FAPI and nFAPI. It is therefore considered very important that we extend these interface specifications for 5G, as 5G-FAPI and 5G-nFAPI."

“FAPI helps Equipment Vendors to mix PHY & MAC Software from different suppliers via this open FAPI interface. So, FAPI is an 'internal' interface.”

“5G-nFAPI (network FAPI) is a 'network' interface and is between a Distributed Unit and Centralised Unit  of a Split RAN/Small Cell network solution. An open specification of this interface (nFAPI) will help network architects by allowing them to mix distributed and central units from different vendors.”

ShareTechNote also provides some details about FAPI and nFAPI as described by Small Cell Forim here.

Related Documents from SCF:

• SCF082.09.05: nFAPI and FAPI specifications
• 5G PHY API and Networked PHY API
• What is FAPI all about?

Small Cells Densification for 4G & 5G

The recent Small Cell Forum (SCF) press release mentions that: SCF forecasts that between 2015 and 2025, new non-residential small cell deployments will grow at a compound annual rate of 36%, to reach almost 8.5 million, and by 2025 deployments will be 22 times higher than in 2015.

The research also provides an insight into operator’s densification plans, with 40% of operators expecting to deploy between 100 and 350 small cells per square kilometer (indoors and outdoors) in the areas they densify by 2020. Additionally, in the first 2-3 years of deploying 5G New Radio, 58% expect to focus primarily on small cells. The research also shows that the industry is already seeing acceleration of deployments in the Enterprise, where small cell deployments rose by 98% between 2015 and 2017, and are set to grow by up to 1600% from 2015 to 2025.

In addition, SCF also published Release 10 (not a permanent link though), a collection of documents, presentations and videos that present the organization’s vision for the 5G era. This collection is a response to the requirements the Forum spent the summer collating resulting from regional and partner events in India, North America and Latin America. SCF listened to input from operators, across the various geographies, on their key challenges and created a work program designed specifically to resolve the key issues raised.

I will link some SCF documents at the bottom of this post.

Stephane Daeuble, Nokia also published a blog post on this topic not long back. In that he points out:

Nokia looked at the growth in demand facing one operator in a very busy US city. In 2014, traffic density was around 1 Gbps/km2 and was served by an average 20 macrocell sites per km2.

By 2017, traffic density hit 4 Gbps/km2. The operator simply adds 40 outdoor small cells and 50 indoor small cells per km2 to the network. Deploying relatively few small cells allows the operator to meet quadrupled capacity and coverage demand, both indoors and outdoors.

Let’s project these figures forward. By 2025, the operator will need a very dense network to support a ten-fold increase in traffic density. With no scope for deploying more macrocell sites and upgrades to macrocell base stations unlikely to meet the demand, even this extreme density can be supported with the help of small cells. Now we are looking at 150 outdoor and 500 indoor small cells deployed per km2, keeping to the intial 20 macrocell sites. Over the period covered by the study, the average inter-site distance plunges from 240m to 82m – a figure impossible to achieve without small cells.

The most obvious advantage of small cells is their compact physical size. They can be deployed unobtrusively to meet city regulations, giving the network a rapid, yet low cost boost in performance. Not only do they provide much-needed extra capacity and improve indoor coverage, but small cells can aid network balancing by off-loading traffic from the surrounding macrocells. Deployments have shown that, after deploying small cells, some macrocells stay above 60% average RF usage, indicating there was substantial unserved traffic with the macros alone.

If you prefer in-depth technical papers, this IEEE paper on small cell Ultra Dense Networks (UDN) is an interesting read.

Check out my introduction to macrocells & small cells and HetNets if you are looking for a quick refresher on these topics.

Here is a list of new SCF documents on densification

SCF Release 10 Vision for Densification into 5G Era

Overall Vision and Requirements gathering
[SCF110] Vision for densification into the 5G Era: Release overview
[SCF200] Ten trends SCF has driven and vision for 2027
[SCF201] Partners’ Day: Industry alignment on densification roadmap
[SCF202] Mumbai Densification Summit: Asia Market Requirements

Technologies for Densification
[SCF014] Edge Computing made simple
[SCF197] mmWave-based 5G eMBB 5G

Standards and Interoperability
[SCF085] SCF Plugfests and long term vision
[SCF208] Private ePC PlugFest report
[SCF209] Test cases for the Private ePC PlugFest
[SCF196] TR196 Small cell updates to 3GPP SA5

Operations
[SCF203] Operational aspects of densification into the 5G Era
[SCF079] Enterprise deployment process (2017 revision)

Business Models
[SCF204] 5G Era business models and stakeholder engagement
[SCF206] Business case for small cells in healthcare

Market Status and Engagement
[SCF050] Small cells market status report December 2017
[SCF194] SCF operator survey: Deployment plans and business drivers for a dense HetNet
[SCF205] Connectivity in healthcare - an essential service

References of the form [SCFXXX] are linked to their landing page on www.scf.io, where they can be downloaded free of charge.

Multi-vendor LTE Small Cells SON

Before we proceed further, in case the reader is not aware of Self-Organizing Networks (SON), please refer to my old tutorial here.

BT has recently published a white paper on multi-vendor LTE SON based on tests using LTE small cells provided by Node-H and Qucell. From the news posted on Node-H website:

The white paper focuses on the important issue of interference management between small cells. The paper is the result of a joint effort by British Telecom's Research and Innovation group and the technical teams of Qucell and Node-H. It addresses some of the major challenges of LTE HetNets and expands on the work of the 2016 ETSI Plugfest, which was run under the auspices of the Small Cell Forum. The authors’ conclusion is that interoperability between different vendors' SON implementations is achievable and so operators can look forward to robust, seamless and tailored solutions from multiple vendors.

The white paper shows that it is possible to operate mobile networks in which the individual LTE cells execute different ICIC algorithms. These findings challenge preconceptions about SON that are common in the mobile industry and make the case towards larger multi-vendor deployments of LTE small cells and call for bolder efforts in multi-vendor SON testing.

The ICIC algorithms used during these tests have been developed independently and without exchange of technical details between two separate HeNB vendors. Despite this, it has been shown that both algorithms can gracefully co-exist in the same LTE network. ICIC standardization efforts within 3GPP, along with the Small Cell Forum's Plugfest activities, have been key to this success.

The whitepaper embedded as follows and is available to download from here:

Related posts:

• Interoperability and Plugfests for Multi-vendor HetNet's
• X2: The necessity for Interoperability and Interference management in HetNets

Small Cells: Best solution for rural coverage?

I drive around the UK a great deal. While I rely mostly on my phone to call and message/text, I also use it to check tweets, Facebook, emails and most important of all as a Satnav (I'm a big fan of Waze). I often end up in scenarios where I have no coverage so a wrong turn results in my Satnav route failure. This can mean I have to drive around for miles before I can get back on route.

In most countries (including UK) when an operator mentions its coverage, its means population based coverage. The problem is that one may have reasonable coverage in a big town/cities but not on small roads and villages but the operator would have still met their coverage obligation. However this will be changing, at least in UK, with the announcement by EE that they will do a 95% geographic coverage. Kudos to them!

Picture Source: Point-Topic

This map I came across recently shows the rural challenges in Europe for providing connectivity. Whilst not that detailed, I can definitely say from a UK point of view, there are many places outside big towns and cities that have coverage gaps.

Picture Source: GSMA: Digital inclusion in Latin America and the Caribbean - Feb 2016

Picture Source: GSMA: Consumer barriers to mobile internet adoption in Africa - July 2016

As can be seen above, a similar problem is present in Africa and Carribean and Latin America (CALA). In these regions, in addition to the coverage gap, affordability and lack of relevant content are also major issues.

To put it simply in most countries, there is that last 10% of the population for whom coverage is not deemed feasible for the operator.  The problem is that the investment would generally outweigh the revenues. The installation (site, backhaul, etc.) and the maintenance cost would almost always outweigh the profits.

This is one of the challenges that Parallel Wireless* is trying to solve.

What if you can make the deployment very simple and reduce the installation cost and have minimal maintenance cost?

The operator would be far more willing to give it a try. There was an announcement between Parallel Wireless and Telefonica I+D for exactly this reason recently. The small communities wherein these small cells are deployed also have a vital role to play. Not only could they help by making sites available, they can have directly report any issues that would arise. An example of this can be seen in the picture above, demonstrating a small cell deployment in a community center.

An important thing to bear in mind is the support for different types of backhaul for small cells. While cellular/LTE backhaul can allow quick deployment, additional type of backhaul can become available much quicker than anticipated. The small cell deployment should be flexible enough to be able to handle this new change.

A real life example of the above statement can be seen in the picture from a recent site survey.

Finally, I would like to embed this video that explains the Parallel Wireless Rural Solution very well.


Please feel free to add your suggestions in the comments below.

*Full Disclosure: I work for Parallel Wireless as a Solutions Architect. This blog is maintained in my personal capacity and expresses my own views, not the views of my employer or anyone else. Anyone who knows me well would know this.

Wireless densification via HetNet orchestration

According to a whitepaper that was published late last year by ThinkSmallCell:

There are commonly thought to be three ways to densify wireless traffic capacity:
1. More spectrum (expensive, limited)
2. More spectrally efficiency (e.g. LTE rather than 2G)
3. More spatial reuse (i.e. small cells)
But there is also a fourth aspect which can deliver significant additional benefit
4. Orchestration and tighter control. (e.g. SON (Self Organising Networks), traffic steering/shaping across and between all available wireless resources)

This has been a key factor driving replacement of outdated macrocells with “Single RAN” basestation equipment that supports all generations of radio interface. These specifically address (1) and (2) above. What’s needed next is investment in tools and equipment that provides similar flexibility for (3) and (4), scaling to cope with an influx of small cells and introducing real-time management and co-ordination across all available wireless technologies, both cellular and Wi-Fi.

While we dont generally hear a lot about SON nowadays, I know most of the vendors have implemented some or the other aspects of SON in their equipment. Orchestration can definitely have a much bigger impact than SON by itself on the densification.

In 5G, we talk about 'edgeless cells', 'no-edge networks', etc. Orchestration of the network will have a big part to play in this too.

Anyway, here is the whitepaper embedded below and available to download from Slideshare

Super Macros and HetNets

The other day I read the following on Light Reading:

UK operator EE wants to turn its existing macro cell sites into "super macros," according to Andy Sutton, the carrier's principal network architect, speaking at the recent Base Station conference in London.

EE 's plan to super size its macro cell sites fits in to a broader Heterogeneous Network (HetNet) strategy for adding capacity and extending coverage. The operator rolled out the first LTE network in the UK last year, and has now covered 55 percent of the UK population and has 1 million 4G customers.

"Super macro is the first step toward building a HetNet,” said Sutton. “Evolving the macro is the most cost-optimized way to adding capacity into our networks."

But what makes a macro super?

According to Sutton, a super macro would typically have multiple radio access technologies (RAT), three-to-six base station sectors, and operate in multiple frequency bands using carrier aggregation techniques. It could be a standalone base station or a hub for subtended, smaller micro cells. He added that infrastructure sharing is vital to the strategy as well.

Once the operator has sufficiently beefed up its macro cell sites, then it can look to smaller cells to be deployed indoors and outdoors in hotspots or cell edge locations. Sutton described a small cell deployment as an "underlay" to the super macro.

The term super macro isn't exactly new, but the fact that operators are talking about it now indicates just how much more they are looking to do with their existing radio access network (RAN) infrastructure before introducing new small cells or while planning a small cell deployment.

"Within the super macro concept, there's quite a lot operators can do to improve performance," says Heavy Reading senior analyst Gabriel Brown.

Along with adding sectors, using more spectrum bands, or employing carrier aggregation, Brown also includes in the super macro concept using 4x4 and 8x8 MIMO, active antenna systems, vertical sectorization, or beamforming.

The advantage of improving macro sites is that many of the basic elements that go into the total cost of ownership of a cell site are already in place, such as power, real estate rental, and backhaul, according to Brown.

I remember the folks from Ericsson mentioning about Super macros but I had not given any thoughts to it. Well, I went back to see what they have been talking about and found this:

Since it was not very clear, I found some additional information from an NGMN presentation as follows:

The growing synergy between Small Cells and Wi-Fi

The growing synergy between Small Cells and Wi-Fi from Zahid Ghadialy

What is a Metrocell? - definition by Alcatel-Lucent

Looking through an old ALU whitepaper, I found another way of describing Metrocell, so here it is:

Metro cells, the latest evolution in small cells, are based on the same low cost femtocell technology that has been successfully used in home and enterprise cells, but with enhanced capacity and coverage. With higher processing and transmit power, the first generation of metro cells is engineered to serve from 16 to 32 users and provide a coverage range from less than 100 meters in dense urban locations to several hundred meters in rural environments. However, unlike home and enterprise cells, metro cells are owned and managed by a MSP and typically used in public or open access areas to augment the capacity or coverage of a larger macro network.

Small Cells deployment report

Today, I went through the Informa's report on small cells. Some interesting points from the report as follows:

Microcells and picocells are already widely deployed in market but on a lower scale compared with femtocells. Metrocells are expected to enter the market during 2012 through operator trials or pilots and expand significantly during 2014 and 2015 primarily for 3G networks in developed markets and LTE in the US market.