Research & Development White Paper

WHP 368

October 2019

5G RuralFirst: Broadcast Radio Use Case Completion Reports

Andrew Murphy, Raj Khokhar, Simon Chirgwin

BRITISH BROADCASTING CORPORATION

White Paper WHP 368

5G Rural First: Broadcast Radio Use Case Completion Reports

Andrew Murphy, Raj Khokhar, Simon Chirgwin

Abstract

As part of the 5G RuralFirst project, we have been working on a 5G Broadcast Radio trial, testing 4G/5G broadcast to deliver live radio services. The delivery of radio is of particular interest in the context of 5G since radio is a naturally mobile medium and a significant proportion of radio listening is in vehicles and on the move.

The project ran from June 2018 until the end of September 2019.

This White Paper outlines the work done in the project and the results obtained in the form of BBC inputs to the Use Case completion reports that were written to track contributions to the work of the project.

Additional key words:

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White Paper WHP 368

5G Rural First: Broadcast Radio Use Case Reports

Andrew Murphy, Raj Khokhar, Simon Chirgwin

1 Overview As part of the 5G RuralFirst project, we have been working on a 5G Broadcast Radio trial, testing 4G/5G broadcast to deliver live radio services. The delivery of radio is of particular interest in the context of 5G since radio is a naturally mobile medium and a significant proportion of listening is in vehicles and on the move. 5G RuralFirst is one of six projects funded under the UK Government’s 5G Phase 1 testbeds and trials programme and aims to demonstrate new approaches to the deployment of connectivity in rural areas, which traditionally suffer from poor coverage and low bandwidth on both fixed and mobile networks. The project targets a number of use-cases ranging from farming and fishing to Internet of Things (IoT) applications. Traditional unicast distribution of broadcast content to mobile devices on 3G and 4G networks has a number of limitations. In urban and suburban areas, unicast is wasteful of resources as multiple copies of the same data are sent to each terminal, which ultimately leads to network congestion and a poor user experience. In rural environments, it is not usually cost effective to deploy a dense network of mobile base stations, so the coverage tends to be uplink limited. As a consequence, the cell sizes supported for unicast delivery are typically smaller than for broadcast delivery using the downlink alone. The aim of the trial was to investigate the role that 5G could have in delivering BBC services to areas that have traditionally been hard to reach and to understand the benefits 5G could bring beyond super-fast connections in densely populated areas. The 5G Broadcast Radio trial comprised two parts; a public trial based on commercially-available 4G equipment and the in-house development of a standalone ‘5G broadcast’ modem that implements the latest mobile broadcast features that won’t be available in commercial handsets until they support 5G. The first phase of the project ran from June 2018 to end of March 2019. An extension to the project, known as Phase 2, was subsequently approved and ran for six months from the beginning of April 2019 until the end of September 2019. The White Paper outlines the work done in the project and the results obtained in the form of BBC inputs to the project Use Case completion reports that were used to track inputs to the project.

2 The First Phase This section details the BBC’s contributions to the Use Case Completion Report submitted at the end of the first phase of the project in March 2019.

2.1 Use of 5G to Broadcast Live Radio Content

2.1.1 Introduction The Internet is becoming increasingly important to deliver the BBC’s programmes and services and it’s important that everyone in the UK can benefit from these even if they live in areas where Internet capacity has typically been limited. Distribution networks have traditionally been application-specific with dedicated networks deployed to deliver fixed TV reception, radio services,

1 emergency service communications or cellular telephony & mobile Internet access. However, 5G offers the possibility of a single family of technology to deliver these different services.

Figure 1 – Stronsay location

The trial was based on the island of Stronsay in Orkney, an island with a population of around three hundred. This location was chosen in consultation with Orkney Islands Council (OIC) and was picked since it was felt it the technology could bring real benefits to the local people since it currently has almost no mobile coverage, limited fixed broadband capability and limited digital radio coverage. The transmission location was chosen as Stronsay Junior High School, a location which is at the heart of the community both metaphorically and physically. This use case made use of 4G/5G broadcast technology to deliver live radio stations to twenty public trialists who were given a special broadcast-capable Android smartphone. In addition, the participants in the trial benefitted from mobile Internet access for the first time. The aim was to explore whether a more general-purpose infrastructure could be used to deliver radio services and to demonstrate the benefits of combining broadcast delivery for live services with the availability of mobile broadband capability for catch-up services and general Internet use.

2.2 Initial Objectives At the start of the project, we declared a number of specific technical objectives: • Does the technology work? Does it scale? • Switching between broadcast/unicast for efficiency • Broadcast interface aspects between content provider/mobile network and on the handset

2.3 Procurement and Use Case Development In order to try to address the initial objectives, a number of components had to be procured and developed for the trial. Initial predictions for coverage were carried out by the BBC’s Distribution Department and these allowed us to write the specification for the base station transmit power and associated antenna system components. The trial made use of 700 MHz spectrum, 3GPP Band 28. This was chosen due to its good propagation characteristics and the availability of consumer handsets due to the existing use of this band in the Asia Pacific Region.

Figure 2 – Initial predicted coverage based on initial transmission parameter assumptions and an omni- directional transmitting antenna

The base station (eNodeB) was provided by partner Lime Microsystems based on their software- defined radio platform. The design of the RF components is shown below. Note that two antenna options were specified since, with the omni-directional antenna, the initial predictions suggested that Whitehall Village was on the edge of service. Since it was felt important to provide solid coverage in this location, a directional panel antenna was also obtained to concentrate coverage in this area in the event that there wasn’t sufficient field strength delivered by the omni antenna.

Mast-mounted Inside cabinet/building LNA Duplex Cable (pre-amp) filter Downlink Antenna Amplifier Lime SDR

LNA Duplex Cable (pre-amp) filter Downlink Target 10m height Amplifier Gaming PC plus AW3464, omni PCI card 1200x296 mm LimeNET 13.5 kg amplifier chassis +6 dBi (2x20W) (2x 90 W EIRP) AW3463, sector 1000x280x120 mm 10.5 kg +12 dBi (2x 317 W EIRP)

Figure 3 – RF architecture

The conventional unicast network components are supplemented by additional elements to provide the broadcast services, namely a Broadcast Multicast Service Centre (BM-SC) and a MBMS Gateway (MBMS-GW). The resulting network architecture is shown below. Initially a stand-alone core network was used. However, the aspiration is to connect into the 5G RuralFirst core hosted by DataVita.

192.168.0.2 IP Power Switch

192.168.0.100 Spectrum Analyser

WAN: Backhaul Port 1: eNodeB Port 2: BM-SC Port 3: Power distribution Port 4: Spectrum analyser

Amarisoft 192.168.0.77 192.168.0.1 Backhaul Internet eNodeB S1

Asus RT-AC3200 M1 wireless router

192.168.30.77 192.168.30.1 192.168.0.179 MBMS GW BMSC SGmb/ HTTP Content source SGi-mb

LimeNET Core PC eBox PC 5GRF Core

Stronsay Junior High School Site DataVita Figure 4 – Network architecture including broadcast components

The delivery of the broadcast audio is based on MPEG-DASH, a standard that is already used for the BBC’s Internet streaming radio services. It was therefore possible to directly use the BBC’s existing radio feeds to deliver thirteen live radio stations, including BBC Radio Orkney.

Figure 5 – The thirteen live BBC radio stations delivered over broadcast in the trial

After initial delivery of the base station, a significant amount of collaborative work was carried out with Lime to ensure that the performance of the base station was sufficient. In particular, detailed link-budget calculations for both the uplink and downlink were carried out and used to optimise the settings of the base station including Peak to Average Power (PAPR) reduction algorithms and the use of supplemental pre-amplifiers to improve uplink performance. A significant amount of lab- based testing was carried out at the BBC to confirm the performance of the system before deployment.

Figure 6 – Testing of the base station in the BBC R&D laboratory

In order to conduct the trial, a full General Data Protection Regulation (GDPR) impact assessment was carried out. This informed the drafting of the trialist agreement that participants were asked to sign in order to gain the appropriate consent as well as ensuring that trialists’ personal data is handled appropriately.

2.3.1 Application Development A "BBC 5G Radio" Android application was created to allow trialists to consume the live BBC radio services over 5G broadcast. Starting the app presents the user with a list of discovered broadcast services. Selecting one of them loads it into the BBC player component with default user interface which allows the user to play and stop the stream.

Figure 7 – The user interface of the 5G Radio app

The app supports background audio playback to allow the user to use other applications while listening to the radio. An Android notification is used to provide visual feedback to the user, provide another mechanism to stop the stream, and critically to prevent the operating system from terminating the app while multitasking. There are inbuilt mechanisms to communicate with the trialists; a server-driven messaging channel to inform them about developments and a send email action to receive qualitative feedback. 5

Figure 8 – An example message for trialists from the messaging channel

Client-side telemetry was implemented to collect data about the quality of the service being provided and consumption and usage patterns. The app reports playback events when streams are started and stopped and well as periodically reporting if the streams are playing back successfully or were buffering. Information about the user’s geolocation, signal strength and quality are also transmitted so that we can understand the performance characteristics of the network in different parts of the island. Trialists were required to accept Android permissions to enable this before being able to use the app. The BBC Standard Media Player (SMP) component is a shared library for consuming BBC DASH content on the Android platform, so it was important to demonstrate the concepts of consuming multicast streams using this technology. Due to the hexagonal architecture of the component, the player could be customised to play back the broadcast streams without modification or forking of the source code; an extension point was added so that when attempting to play back a discovered broadcast service, the third-party 5G broadcast component was invoked to surface the service as a locally served DASH stream, which was then returned back to the player.

2.3.2 Network Deployment An initial site visit to Stronsay Junior High School was carried out by CloudNet in July 2018. This was followed by a later visit by BBC, OIC and CloudNet in October that included a presentation to a meeting of the Stronsay Community Council to explain the ideas behind the trial. The Ofcom licence applications were coordinated through University of Strathclyde who made the specific applications to Ofcom for the use case. Similarly, SIM cards and PLMN values were supplied and coordinated by the University of Strathclyde. The relevant ICNIRP calculations were also carried out as part of the planning permission process and the safety of the system confirmed by the use of a Radio Frequency (RF) hazard meter. With procurement and initial testing complete, the equipment was shipped and installed in the loft space at Stronsay Junior High School in December 2018 ahead of the antenna installation.

Figure 9 – 4G/5G base station equipment installed in the roof void of Stronsay Junior High School

CloudNet, as well as providing the Internet backhaul, were tasked with installing the antennas for the trial. They therefore liaised directly with the relevant building control officers at OIC to gain approval for the physical antenna installation at Stronsay Junior High School. After a couple of aborted attempts at the installation due to both weather conditions, complications relating to the building fabric and the need to construct additional steelwork, CloudNet successfully completed the antenna installation in mid-February.

Figure 10 – CloudNet completing the installation of the antennas at Stronsay Junior High School (top - omni antenna; bottom - panel sector antenna)

2.3.3 Public Trial Launch The main trial launch was scheduled for the week commenting 18th February. Ahead of this, and in order to recruit members of the public to take part in the trial, a promotion campaign was instigated. In consultation with the head teacher of Stronsay Junior High School, it was agreed that ten handsets would be set aside for interested parents of senior school pupils at the school, leaving ten for other people living on Stronsay. We setup a dedicated support email address and phone number with voicemail for the trial. Given the radio-focussed nature of the trial, we were keen to recruit regular radio listeners and were grateful for the help of colleagues from BBC Radio Orkney in publicising the trial. We also took out an advert in the local Orcadian newspaper (below) as well as the Stronsay Limpet.

Figure 11 – Advert placed in the Orcadian to publicise the trial

Following on from this publicity, we held a public meeting at Stronsay Community Hall on 20th February to explain, not only the trial itself, but 5G more generally (below). This was attended by around fifty people.

Figure 12 - The public meeting to explain the trial as well as 5G

While there was generally a lot of support for the trial, there was a significant minority of people concerned about the safety of 5G in general.

Figure 13 – Public interest in seeing the handsets at the end of the public meeting

Around the public meeting, the final setup of the base station equipment was completed and live testing carried out on Stronsay including drive testing to ascertain the extent of the coverage area.

Figure 14 – Network testing in Whitehall Village

Shortlisting was also carried out to select trialists after the public meeting; the main criterion being that they were inside the measured coverage area. There then followed two days in which the prospective trialists were contacted and invited to come along and sign up for the trial and be handed their phones. In addition to the handsets, trialists were given a Bluetooth speaker to offer enhanced audio volume and a car charger.

Figure 15 – Members of the public sign-up for the trial and collect their handsets

2.3.4 Public Trial Results During the course of the trial both quantitative and qualitative data were collected via technical telemetry information and a cycle of market research respectively. Technical Telemetry Data A Ruby on RAILS database server was developed as part of the trial to capture detailed telemetry data recorded by the handsets as people listened to the radio during the course of the trial. A dedicated web application has been developed to interrogate the database and to visualise the data. This enables us, for example, to build-up an anonymised, crowd-sourced coverage map across the whole island and to assess the performance of different transmission parameters on the quality of service. Crucially, it allows us to make an analysis over a much longer time period and over a wider area than drive testing alone would allow and, because the data is coming from real- life handsets, gives us a much more accurate picture of how the technology is working in reality. So far, over 10,000 data points have been collected, and while there is much more analysis to be done, the map below gives an indication of the received power from the base station across the island based on this data.

Figure 16 – An anonymised, crowd-sourced coverage map showing the received power (RSRP) from the base station across the island

Market Research The 5G RuralFirst 5G Broadcast trial is being supported by consumer research – conducted by MTM on behalf of the BBC – to explore the experiences of the nineteen trialists taking part. In particular, the research is exploring the impact of the trial service on participants’ internet habits, and their use of radio services via a bespoke app provided by the BBC. The consumer research is running over a period of around five weeks (February 25th – March 29th), with trialists completing a variety of tasks to chronicle their experiences. The tasks include four online surveys & four video blogs per trialist, eight telephone interviews with selected participants, and a wrap-up group discussion event to be held in Stronsay in mid-April. We’ve provided an initial snapshot of some emerging findings below, drawn from responses received over the first few weeks of the trial: Pre-trial habits • Internet use already a part of daily lives for trialists, but their online activities are currently limited by low speed and unreliable internet connections o Regular internet use is the norm for the vast majority of trialists, with around 8 in 10 using the internet several times a day o However, there’s widespread dissatisfaction with internet connectivity options currently available on Stronsay, with around three quarters feeling that it limits them from doing everything they’d want to do online o Almost all trialists listen to radio services daily, but face challenges in terms of the reception quality and reliability of reception available o Over half dissatisfied with the radio reception currently available on Stronsay, with issues including variable reception in different parts of the island, frequent loss of signal and a limited range of stations available Initial responses to the 5G trial internet service • There’s generally been a very positive response to the trial service and its impact, amidst a backdrop of dissatisfaction with existing internet and radio options

o Almost all (around 9 in 10) are satisfied with the trial internet service, with a similar number feeling that it’s lived up to their expectations o While signal strength varies in relation to proximity to the 5G antenna, over half of participants describe the trial phone internet as faster than previous options, with around two thirds feeling that it’s more reliable o The trial service is particularly valued for its consistent connection and the freedom offered to use it most places, whether in or out of home • Widespread satisfaction with the quality of signal and range of listening options provided by the radio app o While listening habits broadly reflect trialists’ existing service preferences, there’s evidence of a broader repertoire of stations being listening to via the trial app o In particular, there’s increased use of digital-born stations (e.g. Radio 1 Xtra, Radio 4 Extra), with limited reliable DAB previously forestalling use o Those preferring the trial radio app to previous alternatives cited its greater reliability (‘less wiggling of aerials’!), the flexibility to listen on the move and the variety of stations available

2.3.5 5G Modem Development With current off-the-shelf handsets and network equipment we are limited to using somewhat earlier releases of the broadcast specifications (typically 3GPP Rel-12). The development of our own 5G Broadcast Modem (transmitter and receiver) enables us to explore the capabilities of the latest features of 5G Broadcasting (3GPP Rel-14/15) including: • Free-to-air/SIM-free reception • Stand-alone transmissions • Transparent-mode operation • Transmission parameters to support handheld, vehicle-mounted and rooftop antenna reception Figure 17 below shows the modem hardware running in the lab. It is based on custom VHDL code running in a Xilinx FPGA to enable transmission of a Release 14/15 compatible signal.

Figure 17 – 5G Modem hardware and transmitted output spectrum (5 MHz bandwidth)

2.3.6 Conclusions The interim conclusion is that the broadcast system works well and has been generally well received by the trialists and the original objectives have been satisfied. It’s clear that the technology works and that a software-defined radio approach is capable of providing a reliable and robust service to the public. While there wasn’t been time to address seamless switching between broadcast and unicast for efficiency, the expectation is that this will be explored within a potential extension to the project. The fact that it has been possible to use the BBC’s existing MPEG-DASH sources directly for the broadcast as well as re-use existing BBC Application components 12 unchanged has demonstrated a path to how 5G Broadcast could be delivered to users in the future. As a result of the work to deliver the 5G Broadcast use case, several key issues have been identified, specifically: • Uncertainty around the PLMN allocation process as a result of the 5G RuralFirst use cases not being delivered by an established Electronic Communications Code operator or Mobile Network Operator; • More widespread public concerns over the safety of 5G than anticipated; • The importance of controlling the Peak to Average Power Radio (PAPR) of the transmitted signal in order to maximise amplifier performance; • The importance of up-link sensitivity of the base station and resulting link budget calculation to ensure that this isn’t a limiting factor in coverage of general Internet access; • The start-up time on the broadcast streams being longer than desired due to the re-use of MPEG-DASH streams optimised for unicast (rather than broadcast) Internet streaming; • The bit-rate of the live audio streams appearing to be somewhat higher than expected resulting in the broadcast streams running behind in time and the need to dimension the fixed bit-rate broadcast bearers at a higher rate than expected to solve this; and • The broadcast part of the signal only being emitted from one of the antenna ports of the base station rather than both, resulting in 3 dB less signal than anticipated.

2.3.7 Future Work A number of areas have been identified for work within the potential extension of the project, specifically: • Integration of the use case with the 5G RuralFirst 5G core; • Further testing of the dedicated 5G Modem; • Development and roll-out of the broadcast-enabled BBC Sounds Application to users; • Seamless broadcast/unicast switching; • Testing of different transmission parameters (modulation, coding and audio segment duration); • Further, detailed data analysis; and • Programme production and contribution tests.

2.3.8 Acknowledgements The authors would like to particularly thank Stronsay Junior High School and the Stronsay Community for hosting and taking part in the trial.

3 The Second Phase

The extension of the overall 5G RuralFirst project for a further six months allowed a number of additional use cases to be developed. The BBC was involved with two of these, entitled: • “The Extended Application Use Case on 5G Broadcast”; and • “5G Broadcast: Additional Broadcast Use Cases”. The completion reports addressing each of these are presented in the following clauses.

3.1 The Extended Application Use Case on 5G Broadcast

3.1.1 Overview of Use Case (5G Broadcast) The Internet is becoming increasingly central in delivering the BBC’s programmes and services and it’s important that everyone in the UK can benefit from these even if they live in areas where Internet capacity has typically been limited. Distribution networks have traditionally been application-specific with dedicated networks deployed to deliver fixed TV reception, radio services, emergency service communications or cellular telephony & mobile Internet access.

Figure 1 – Stronsay location

The trial was based on the island of Stronsay in Orkney, an island with a population of around three hundred. This location was chosen in consultation with Orkney Islands Council (OIC) and was picked since it was felt it the technology could bring real benefits to the local people since it currently has almost no mobile coverage, limited fixed broadband capability and limited digital radio coverage. The transmission location was chosen as Stronsay Junior High School, a location which is at the heart of the community both metaphorically and physically. This use case made use of 4G/5G broadcast technology to deliver thirteen live BBC radio stations to twenty public trialists who were given a special broadcast-capable Android smartphone with a dedicated ‘5G Radio’ app installed. In addition, the participants in the trial benefitted from mobile Internet access for the first time. The aim was to explore whether a more general-purpose infrastructure could be used to deliver radio services and to demonstrate the benefits of combining broadcast delivery for live services with the availability of mobile broadband capability for catch-up services and general Internet use. The work in Phase 2 allowed for further audience research, data collection and analysis.

3.1.2 Network Infrastructure Supporting the Use Case The Phase 2 work used the existing network infrastructure that had been deployed in the first phase of the project as set out in the use case final report from the first phase. To summarise, the system made use of a software-defined eNodeB supplied by Lime Microsystems with a stand- alone unicast core network supplemented by additional elements to provide the broadcast services, namely a Broadcast Multicast Service Centre (BM-SC) and a MBMS Gateway (MBMS- GW). Internet Backhaul was provided over a wireless link by Cloudnet.

3.1.3 Use Case Operation Over the course of the extension, we have continued to support the twenty trialists who have been taking part, including arranging for the return and repair of a number of handsets which failed over the course of the second phase. We have also carried out both qualitative and quantitative research on the performance of the system. Trialist Engagement 14

To keep a dialogue with trialists remotely we encouraged email feedback which was supported directly from the 5G Radio application. One particularly helpful trialist kept us abreast of network and power outages on the island, which supported the installation of an Uninterruptable Power Supply (see WP8). Technical clinics were run on the island to provide support for any issues such as how to use the app or the service, deploying updated app versions and returning devices for repair. Community engagement was high, and meetings provided an opportunity to ask about their personal experiences of the trial. Some educational support was also provided by helping one of the trialist's children to develop their first mobile application, which followed on from a short career talk we had given at the school on a previous visit to the island. Audience Research We commissioned an audience research company to engage with the trialists during a five-week period to determine qualitatively how the trial service was received. The research consisted of: • Four online self surveys served across the five-week research period, grounded in understanding current internet and radio habits, through to exploring online and listening experiences across the trial; • Four self-filmed video blogs alongside each of the four surveys, where participants were tasked with chronicling experiences in their own words across the trial; and • Eight telephone interviews split between four at the midpoint of the trial and four at the end. The interviews were up to 45 minutes with selected trialists to delve further into emerging insights from surveys and video blogs. In addition, a wrap-up group discussion event was held at Stronsay Community Hall on 16th April 2019. The aim was to explore trialists’ experiences vs. expectations of the service and radio broadcasting over the 5G trial network. It was also an opportunity for the BBC to engage directly with the trialists and to gain a more nuanced understanding of their experience by hearing it directly from the participants. In summary, before the trial period: • Internet use was already a part of daily lives for trialists, but their online activities were limited by low speed and unreliable connections. • Regular Internet use was the norm for the vast majority of trialists, with around 8 in 10 using the internet several times a day. • However, there was widespread dissatisfaction with Internet connectivity options currently available on Stronsay, with around three quarters feeling that it limits them from doing everything they’d want to do online. • Almost all trialists listen to radio services daily, but face challenges in terms of the reliability and quality of reception available. • Over half were dissatisfied with the radio reception currently available on Stronsay, with issues including variable reception in different parts of the island, frequent loss of signal and a limited range of stations available. During the trial period: • A very positive response to the trial service and its impact during the research period, amidst a backdrop of dissatisfaction with existing Internet and radio options. • Almost all, around 9 in 10, were satisfied with the trial Internet service during the research period, with a similar number feeling that it lived up to their expectations.

• While signal strength varies in relation to proximity to the 5G antenna, over half of participants described the trial phone internet as faster than previous options, with around two thirds feeling that it’s more reliable. • The trial service was particularly valued for its consistent connection and the freedom offered to use it most places, whether in or out of home. • Widespread satisfaction with the quality of signal and range of listening options provided by the radio app. • While initial listening habits broadly reflected trialists’ pre-trial service preferences, there’s evidence of a broader repertoire of stations being sampled. • Those preferring the trial radio app to previous alternatives cited its greater reliability (‘less wiggling of aerials!’), the flexibility to listen on the move and the variety of stations available. At the end of the trial period: • A large majority of participants retained positive perceptions of the trial internet service, which was mainly used to enhance existing online activities. • Most lasting value among those receiving a reliable connection (residing well within the 5G coverage area) and larger households (especially those with school age children). • While most used it to boost existing online activities, the majority recognised wider potential benefits in helping people remain connected out of home and in streaming audio and video content. • While generally positively perceived at the end of the trial period, there were reservations around technical issues impacting the radio app. • Greatest enduring impact among those living in areas with previously poor radio receptions and avid consumers of radio and other audio content. • Impact of 5G radio services likely to be significantly boosted if technical teething problems can be overcome, since they can currently frustrate trialists and make the radio app seem like hard work compared to existing radio options. • A large majority of trialists positively perceived the BBC’s involvement in the 5G trial. • Valued for being a public institution not seeking to profit and for serving people like them in rural areas Data Collection The extension to the trial allowed the collection of quantitative data from trialists for a further six months and to perform more detailed analysis on it. This has allowed us to characterise the performance of the broadcast system in some detail. The transmission parameters for the broadcast components were set as follows: • Antenna: Omni directional, +6 dBi gain • Transmission power: 90W EIRP • eMBMS sub-frame allocation: 60% • Signalling Modulation and Coding Scheme (MCS): 2 • Data Modulation and Coding Scheme (MCS): 3 • Application Layer FEC Overhead: 75 % One metric of interest is the signal strength (RSRP) required for the broadcast streams to be received correctly. The first step is to work to identify when the stream is working and when it is not. To this end we consider heartbeat, buffer and stop events that are reported by the telemetry from the device when the radio services are being listened to and recorded in the logging database. 16

Where a sequence of X (X = 10, for example) consecutive heartbeat events, or buffer or stop events, are found then: • If we have X heartbeat events, then the stream is deemed to be working, and we record the RSRP and RSRQ for the events at position X, X+1, X+2, … until we encounter a non-heartbeat event. This period of heartbeat events is considered a working session. • If we have X buffer or stop events, then the stream is deemed to be not working, and we record the RSRP and RSRQ for the events at position X, X+1, X+2, … until we encounter a non-buffer or non-stop event. This period of buffer or stop events is considered a not working session. Note that it is not possible to simply use a single buffer event to determine if the stream is working, since we might expect a buffer event when a stream is first started for example. By plotting the proportion of working versus not working sessions against the signal strength level we achieve Figure 18 below. Here we see that the proportion of not working sessions begins to increase at an approximate RSRP of -113dBm and drastically decreases at approximately -124dBm. We can plot these working and not working sessions geographically, see Figure 19. Here we see, as expected, that the streams tend to work less as the distance from the base station increases. This is supported by Figure 20, in which we see a heatmap of the RSRP. Onto this heatmap we have drawn lines at approximately -124dBm (which we see from Figure 18 is the point where a significant increase in the proportion of not working sessions is observed).

Figure 18: Bar chart of the proportion of working sessions (in green) and not working sessions (in red) against the RSRP. We remove data for power levels with less than 50 data points.

Figure 19: Working against not working sessions plotted geographically. The marker in the centre indicates the base station.

Figure 20: A heatmap of the RSRP. The area enclosed by the red lines has approximately a higher proportion of working sessions to not working sessions. The marker in the centre indicates the base station.

3.1.4 Outcomes from Use Case The audience research indicates that there was a very positive reaction to the 5G broadcast radio trial among the participants. The trialists identified a number of technical issues with the broadcast radio service provided by the application which have been addressed by the network coverage optimisation addressed in WP8. The quantitative data analysis has given a good indication of the required signal strength for a given set of technical parameters for the broadcast service to work on the trial handsets.

3.1.5 Conclusions This use case report outlines the audience research and further data collection and analysis carried out in Phase 2 of the 5G Broadcast use case. The audience research identified a number of network optimisations to be examined in WP8 including: • Reducing the delay in the radio streams; • Improving service reliability; and • Improving start-up times of the streams. Overall there was a very positive response to the trial service and its impact during the research period.

3.2 5G Broadcast: Additional Broadcast Use Cases

3.2.1 Overview of Use Case (5G Broadcast: Additional Broadcast Use Cases) The Additional Broadcast Use Cases for 5G Broadcast encompassed three main aspects: • Network coverage optimisation of the existing network on Stronsay supporting the 5G Broadcast use case; • Connection of the Stronsay base station to the 5G RuralFirst 5G core; and • Programme making and contribution over 5G networks, i.e. a demonstration of the use of the 5G RuralFirst network for making broadcast programmes from an Outside Broadcast. In the following text, each of these aspects is addressed, along with details of trialist engagement activities.

3.2.2 Network Infrastructure Supporting the Use Case For the network coverage optimisation piece, the Phase 2 work used the existing network infrastructure on Stronsay that had been deployed in the first phase of the project as set out in the use case final report from this first phase. To summarise, the system made use of a software- defined eNodeB supplied by Lime Microsystems with a stand-alone unicast core network supplemented by additional elements to provide the broadcast services, namely a Broadcast Multicast Service Centre (BM-SC) and a MBMS Gateway (MBMS-GW). Internet backhaul was provided over a wireless link by Cloudnet. In addition, further audio encoding and packaging infrastructure was provided within BBC R&D’s laboratory environment. In the case of the programme making and contribution demo, tests were carried out from other sites in Orkney where the 5G RuralFirst network was available since it had not been possible to connect the Stronsay base station to the 5G Core.

3.2.3 Use Case Operation The operation of the network on Stronsay continued in this Phase 2 as it had in the first phase. In the case of the programme contribution trial, infrastructure from other parts of the 5G RuralFirst network were utilised as set out below. Trialist Engagement Throughout the project the team have endeavoured to maintain a high level of engagement with the trialists. They were able to provide a valuable insight into the perception of service quality and further describe their needs from the service.

One of the key activities was an audience research session facilitated by a third-party (detailed in WP2). Trialists were asked to feedback on a range of themes such as the quality of broadcast radio, speed and reliability of network connectivity, and their internet usage before and after the trial. The outcomes from both activities were used to shape the network coverage optimisation work carried out in WP8 in this use case, in particular: • Reducing the delay in the radio streams; • Improving service reliability; and • Improving start-up times of the streams. Reducing the delay in the radio streams Experiments in the laboratory at BBC R&D on a mirror of the broadcast system deployed on Stronsay quickly identified that, over time, the delay of the radio services delivered over the Broadcast was increasing compared with conventional analogue radio services meaning that the programmes heard on the 5G Broadcast service were increasingly behind live. Further investigation revealed that this was due to there not being enough capacity for each of the broadcast streams due to the significant overheads of the protocol (FLUTE) used in eMBMS to convey the relatively small MPEG-DASH segments of the radio streams. This effect was characterised by taking captures of the network traffic carrying the broadcast services and making appropriate changes to the configuration of the broadcast transmissions to correct it. Following soak testing in the laboratory, the relevant changes were rolled out to the base station on Stronsay via the remote access on 04/03/2019 and a notification sent to users of the radio application. Additional telemetry information was also added into the 5G Radio App to track and log the difference between the actual time of day and the ‘play head’ time of the broadcast streams. Improving service reliability – Uninterruptable Power Supply Limitations on the available transmit power meant that it was not possible to make an increase in order to extend the coverage area of the service. However, one source of significant disruption was the relatively regular occurrence of short mains power interruptions, after which a manual re-start of the equipment was required to ensure it was still operating within specification. The procurement and installation of an Uninterruptable Power Supply (UPS) addressed these problems (shown in bottom right of the picture). The UPS was found to be very beneficial in terms of improving the reliability of the trial network on Stronsay, as illustrated by this snapshot (Table 1 below) of the power interruptions seen by the UPS over the last 30 days of the trial. Previously each of these would have resulted in an outage and a remote reset of the network the next working day whereas with the UPS, only the outage on September 3rd required manual intervention following a longer power outage that overwhelmed the capacity of the UPS back-up batteries.

Status Time Event INFO September 25 2019 18:07:11 Power Restored WARNING September 25 2019 18:07:10 UPS On Battery INFO September 25 2019 17:43:24 Power Restored WARNING September 25 2019 17:43:22 UPS On Battery INFO September 15 2019 01:40:40 Power Restored WARNING September 15 2019 01:40:37 UPS On Battery INFO September 03 2019 09:52:57 Communications Established CRITICAL September 03 2019 08:52:42 Communications Lost Table 1 - Power outages on Stronsay

Improving service reliability – Improved Retry Mechanism The audience research with the trialists indicated that they were discontented with quality of the radio experience when travelling in and out of areas with poor connectivity. The BBC Standard Media Player (SMP) User Interface (UI) has a retry button for when failback fails but users were not accustomed with having to manually restart radio streams, and this is obviously not advised in situations such as when driving. SMP also has a mechanism for automatic retries, ContentConnection getConnection/failover methods, which are typically used for Content Delivery Network failover. However, it had the following limitations for our use-case: • Failover operates transparently by design; the user receives no feedback about retries being attempted and the app remains in the buffering state with a loading spinner displayed. • What constitutes a timeout or playback failure is dictated by the decoder, and in our case ultimately Exoplayer, so we were unable to create a predictable experience. In answer to this we implemented a retry mechanism outside of SMP, based upon our own timer. We could present the user with visual feedback using a progress bar to show them how long before we would attempt to restart the stream (shown in Figure 21 below). When the timeout occurs, we call SMP stop and load APIs to tear down the playback session and start again without any internal SMP state.

Figure 21 - Radio app retry mechanism 21

The new release of the 5G Radio application was made available to trialists ahead of a trialist’s drop-in session that was organised at Stronsay Community Centre on the evening of 24th July. This was advertised to trialists so that they could come and ask us about any aspect of the service as well as receive help in upgrading the software on their phones. This included an upgrade to the ‘middleware’ broadcast component that could not be delivered to the handsets remotely. The event was also advertised to the wider community through the Stronsay Community Council so that members of the community outside of the trial participants could get an update on the trial. Reducing stream start-up time In order to reduce the start-up time of the radio services, it was necessary to reduce the length of the MPEG-DASH segments used for the broadcast services. At start-up, the audio player has to buffer one of more segments before starting to play and, since the segments are delivered in real- time over the broadcast, the player must wait for at least one or two complete segments to be received. Initially the broadcasts were fed by the standard streams that the BBC publishes for Internet delivery over MPEG-DASH and these are optimised for conventional streaming (unicast). With a segment length of 6.4 s, there is a potentially significant start-up delay. An internal BBC R&D server was used to re-package the streams into shorter segments of one second. Crucially the design of this system is such that it does not require the audio to be re- encoded, thereby maintaining the audio quality. The new streams were then soak tested in the laboratory at BBC R&D before being later deployed in Stronsay. Implementing shorter stream start-up times was mostly transparent to the application and Exoplayer was able to handle the smaller segments sizes successfully. With the changes there was increased incidence of re-buffering in the player occurring shortly after the stream had commenced. It was suspected this was buffer underflow caused by loading subsequent segments at the same time as other player start-up overheads. This time was previously much greater. In order to compensate for this, a configuration parameter was changed in the broadcast ‘middleware’ software installed on the handsets (the ‘MPDNotificationThreshold’ parameter was set to 3 seconds). This extended the buffering time inside the middleware before the application was provided with the DASH manifest URL, which alleviated the problem while largely maintaining the improved user experience. Experimentally the start-up time is defined as the time between a start event (which is triggered when the user starts a stream) and the next heartbeat event (which is triggered when the stream begins to play). The change to improve the start-up delay was made on the 23/08/2019. We can see from Figure 22 that in the region of time before the 23/08/2019 the stream start-up time is notably higher than afterwards; we have discounted start-up times greater than 20 seconds, since these are very rare and so likely due to other factors.

Figure 22: Time to start, in seconds, for the period between 1/6/2019 and 23/9/2019.

Connection to the 5G Core There was an aspiration to connect the Stronsay base station to the Cisco 5G core hosted by DataVita as outlined conceptually in Figure 23 below. This would have replaced the core running locally on the ‘LimeNet Core PC’ depicted in the figure.

5G Broadcast Radio use case, Stronsay: 192.168.0.2 IP Power Switch Proposed connection to 5G Core

192.168.0.100 Spectrum Analyser

WAN: Backhaul Port 1: eNodeB Port 2: BM-SC Port 3: Power distribution Port 4: Spectrum analyser

Amarisoft eth0 192.168.0.77 192.168.0.1 Backhaul Internet eNodeB S1

Asus RT-AC3200 M1 HTTP wireless router S1 (over secure tunnel) eth1 192.168.30.77 192.168.30.1 192.168.0.179 MBMS GW BMSC eth1 eth0 SGmb/ Internet-facing Content source SGi-mb tunnel end-point

LimeNET Core PC eBox PC 5GRF Core

Stronsay Junior High School Site DataVita Figure 23 - Proposed architecture for 5G Core connection (new components in red)

Unfortunately, a number of technical hurdles were encountered, in particular the need to separate the user (data) and control traffic that is not natively supported by the Amarisoft software being used in the Stronsay base station. The original intention had been to deploy the 5G core connection while the BBC team visited Stronsay for a trialist drop-in session in July since it is not possible to make such fundamental changes to network configuration remotely. Unfortunately, it was not possible to find a solution to this issue ahead of the site visit, which meant that it was not possible to deploy this solution in the field. Programme Contribution over 5G The original intention based on the editorial plan had been to carry out a live programme contribution test from Stronsay once it was connected to the 5G Core. However, since it was not possible to make the connection to the 5G core, it was decided to carry out this test from other sites in Orkney where the 5G RuralFirst network is available. 23

The site chosen for this was the Ness of Brodgar where this year’s archaeological activity would be wrapping up with the end of summer, providing a good pretext for the broadcast. However, further delays by our supplier in providing a stereo, bi-directional audio circuit between Glasgow and Kirkwall (needed in order to insert the programme into the BBC Scotland’s fixed broadcast path) pushed the likely test date beyond the date for the dig’s closure. As no other event warranting a full transmission was going to take place within range of the Rural First network before the end of the trial on the 30th September, the extent of testing was scaled back, removing the live transmission aspects but crucially nonetheless allowing the main points of the assessment criteria to be met. The four original assessment criteria had been identified as: • Audio Quality – measured both in terms of the achieved stream bandwidth and the stability and fidelity of the decoded audio stream as perceived by a listener; • Network Delay – both directly as experienced when a connection is made from encoder to decoder and also when the connection is passed via interim decoding/encoding at an intermediary location such as Glasgow; • Ease of use – the complexity involved in connecting to the 5G network using standard broadcast equipment; and • Effect of network slicing – It was hoped that the effect of isolating the contribution from the effects of network contention across the whole 5G network would be able to be assessed, at least in an emulated form. Due to the configuration of the network in Orkney it was not possible to test against the fourth criterion, intended to gauge the effect of network slicing on constant-bitrate traffic; however, given the availability of more than enough bandwidth for our purposes, it is unlikely that we would have been able to easily simulate contention in the first place. The following tests were carried out at locations where there was access to the 5G core, around the fourth Churchill Barrier, linking South Ronaldsay to the smaller island of Burray: 1. Network performance tests, using the command line tool iperf, to assess any limitations of capacity resulting in packet loss over time. 2. Spoken contribution tests of audio made between the test location and an ‘interviewer’ in the Radio Orkney studio. Data streams consisted of speech (rather than music) quality audio, represented the sort of content that would be required for contribution to a live radio news programme. 3. Long-duration stereo audio tests decoded and recorded at the BBC’s premises in Birmingham; data streams were uncompressed, carrying high-quality audio, simulating the sort of traffic that would be used for live concerts to be broadcast by Radio 3. All data streams were carried over the 5G core as far as the Datavita data centre in Glasgow; from there they transited the public internet to the BBC’s firewalls, before reaching their destination inside the BBC network. The interview material (test 2 above) was connected by the BBC’s Session Initiation Protocol (SIP) Session Border Controllers (SBCs) with the Real-time Protocol (RTP) audio streams being decoded at BBC Glasgow before being passed on to the studio in Kirkwall. The stereo streams were connected directly to decoders in the English Regions test facility Birmingham, where the decoded audio was passed as ‘AES’ digital audio streams to be recorded.

Datavita 5GRF Core

Internet PoP

WWW

NETGEAR

Ethernet

COMREX Comrex Access Codec/Mixer Linear PCM (mono) & AAC Stereo Streams

iF Phone

BBC Luci App Firewalls (WebRTP)

iPerf Stereo Audio Stream WebRTP via SIP BBC Contribution Tests Audio Stream Decoded in Glasgow and then forwarded over BBC Core Radio BBC Orkney Recorders

High Bandwidth Audio Stream Decoded in iPerf Birmingham and Burray (Orkney Islands) recorded locally BBC Facilities Destination

LABEL 5G Contribution Testing, Burray, Orkney, 25th-27th September 2019

REV. DESCRIPTION DATE BY 1.0 Distribution Copy 29-ix-19 SMC Figure 24 - 5G Contribution Testing, Burray

While there has not yet been time to fully evaluate the results (the tests were carried out between Wednesday 25th and Friday 27th September) the initial impression is favourable, with some caveats. The ease of use was comparable to other carrier methods. The hub tethered to the 5G RuralFirst network without difficulty and thereafter connecting to the test endpoints was straightforward and simple (an important consideration given that much of the expected use of 5G connectivity will be made by non-technical editorial staff, operating on their own and often in less-than-ideal weather conditions). There were also times when the only method of connecting to colleagues in the BBC was over the 5G RuralFirst network as mobile reception and 4G availability was often non-existent in the south isles of Orkney; the ability to make calls using Skype or Facetime using an iPhone wirelessly connected to the tethered hub was a pleasing (and reassuring) bonus. Delay on the complete circuit was pretty much indiscernible by the user (at either end in the case of the interview-type tests carried out with the participation of Radio Orkney). Perceived audio quality was excellent in both use cases. Speech was clear and the longer actuality recordings also were markedly better than similar audio passed over 64kb/s ISDN connections without the need for additional channels or more complex encoding equipment. There were some instances of ‘glitching’ – sudden reductions in the quality of the audio stream and of ‘drop outs’ where the audio stopped for fractions of a second, but – without more detailed analysis of the traffic – it is not possible to tell whether these occurred due to some problem within the 5G core or during the transit of the public Internet (or at the 5G network’s point of presence on the public Internet) before it reached the BBC firewalls, prior to decoding. However, it should be noted that there was also significant packet loss during the network performance tests (carried out in Burray, in Cloudnet’s premises in Kirkwall and in the West Mainland on parts of the 5G RuralFirst network that used existing connectivity for its backhaul) whenever the iperf stream exceeded 10 Mb/s. It is possible that individual connections to the mast on South Ronaldsay have been capped at around the 10 Mb/s mark, but this is a technical constraint we will need to check with partners University of Strathclyde and Cloudnet. Again, it is possible that this was a restriction found within the public Internet section of the streams’ carriage, rather than anything to do with the 5G part of the path.

More analysis should be possible over the coming weeks, after the end of the trial proper in Orkney. Follow ups to this short series of tests – should the network continue to be available beyond 1st October – will include the originally-planned full broadcast and more long-term monitoring of all stages of the network chain between the contribution site and the final BBC destination.

3.2.4 Outcomes from Use Case A number of steps have been taken to optimise the network coverage and operation on Stronsay, based on feedback from engagement with the trialists. In particular, data collected from the telemetry shows that the average stream start-up time fell dramatically as a result of the configuration changes carried out. Unfortunately, it wasn’t possible to make the connection into the 5G core network due to a number of factors as previously detailed. The programme contribution demo has shown the possibilities of the 5G RuralFirst network for programme contribution. However, further work is needed to characterise some issues in the transmission path, particularly the sources of packet loss.

3.2.5 Conclusions The audience research and feedback from trialists have been used to optimise the 5G Broadcast network on Stronsay. It is particularly interesting to note that seemingly simple improvements, such as the deployment of an Uninterruptable Power Supply (UPS), can be very beneficial and significantly improve the service in the eyes of the trialists. It is also a reminder of the challenges of deploying this type of infrastructure in areas where there are more interruptions to the power supply than might be common in more urban areas. Valuable learnings around the overheads associated with the protocol used for the delivery of the broadcast radio streams will be used for capacity planning in future trials and the additional telemetry proved invaluable in confirming that the problem of increasing time delays in the radio streams had been addressed. The programme contribution demonstration showed the potential of the 5G RuralFirst network and 5G in general for changing the way that programmes and outside broadcasts are made in the future. However, there is more work to be done to understand certain aspects of the network performance and to also explore more advanced 5G features such as network slicing.