Friday 13 October 2023

The Digital Railway supported by FRMCS

As discussed in our earlier post, the long-standing 2G cellular standard for rail communication, known as the Global System for Mobile Communications–Railway (GSM–R), remains in use across Europe, China, India, Africa, and Australia. However, software and hardware vendors predict that this early digital cellular technology will start to be phased out in 2025, as a new 5G-based system specifically for railway applications is expected to be introduced.

According to the European Union Agency for Railways (ERA), GSM–R supports communication between train drivers and traffic control centres with features such as group communication, location-dependent addressing, priority levels, railway emergency calls, and shunting communication. This system enables data transmission between trains and control centres at speeds exceeding 300 mph.

Yet, GSM–R is beginning to show its age. While it is adequate for basic voice communication, its 4 MHz bandwidth, which supports multiple 200 KHz channels, limits its functionality. Downlink communications use the 876–880 MHz range, while the uplink operates at 921–925 MHz.

The maximum data transmission rate for GSM–R is just 9.6 kbit/s, making it unsuitable for real-time data communication. Its capabilities are essentially limited to sending SMS text messages, with little capacity for anything more advanced.

The Future Railway Mobile Communication System (FRMCS), a 5G-based successor to GSM–R, will provide both voice and data services for railway communications. The FRMCS project is being led by the International Union of Railways (UIC) in collaboration with major rail infrastructure companies and telecom solution providers. It is set to be based on the 5G 3GPP standard, meaning it will not require a railway-specific cellular network technology.

FRMCS, which will use the standalone 5G NR specification, is expected to be finalised by the end of 2022. This new standard will operate on harmonised frequencies at 900 MHz and 1900 MHz to ensure interoperability for rail command and control systems as they transition from GSM–R to FRMCS.

Mobile network operators will also be able to offer 5G connectivity for train passengers, collaborating with railway companies to provide the high-bandwidth digital services needed to streamline modern train operations.

Currently, many rail operators offer Wi-Fi onboard or install repeaters to enhance mobile network coverage within carriages. However, these solutions can be costly to maintain and upgrade, and repeated signals can cause interference when train doors open. An alternative solution is for public mobile operators to provide passenger connectivity through their existing 5G networks, with additional 5G towers placed along major rail lines.

To improve 5G signal penetration, train windows can be fitted with special “5G-friendly” glass, which allows signals to pass through more easily (standard window glass is often coated to reduce solar radiation inside the carriage). This approach reduces the need for expensive Wi-Fi and repeater systems, enabling mobile operators to deliver high-speed broadband services to passengers more efficiently.

In their webinar last year, Wray Castle stated that FRMCS is not simply a replacement for GSM-R nor is it a single specific technology. In fact, UIC have stated that FRMCS is technology agnostic. The webinar discussed:

  • What is FRMCS and how does it differ from GSM-R?
  • How soon will railways be replacing GSM-R?
  • Is there a migration strategy?
  • Do we have sufficient radio spectrum?
  • What is the most probable technology that will be used?

The video of that is embedded below:

Wray Castle also conducts regular courses on this topic. Details here.

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Wednesday 4 October 2023

Presentations from 2nd IEEE Open RAN Summit

The second IEEE SA (Standards Association) Open RAN summit, hosted by the Johns Hopkins University Applied Physics Lab, took place on 9-10 Aug 2023. It covered the topics related to the standardization of Open RAN including O-RAN Alliance, 3GPP, IEEE, various deployment scenarios, testing and integration, Open RAN security, RAN slicing, and RAN optimization among others. 

The videos of the presentations can be viewed on the summit page here or though the video playlist here.

The talk from Dr. Chih-Lin I, O-RAN Alliance TSC Co-Chair and CMCC Chief Scientist, Wireless Technologies on 'AI/ML impact, from 5.5G to 6G' is embedded below:

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Wednesday 13 September 2023

Private Networks Introductory Series

Private Networks has been a hot topic for a while now. We made a technical introductory video which has over 13K views while its slides have over 25K views. The Private Networks blog that officially started in April is now getting over 2K views a month. 

In addition, there are quite a few questions and enquiries that I receive on them on a regular basis. With this background, it makes sense to add these Introductory video series by Firecell in a post. Their 'Private Networks Tutorial Series' playlist, aiming to demystify private networks, is embedded below:

The playlist has five videos at the moment, hopefully they will add more:

  • Introduction to different kinds of mobile networks: public, private and hybrid networks
  • Different Names for Private Networks
  • Drivers and Enablers of Private Networks
  • Mobile Cellular vs Wi-Fi Private Networks
  • Architecture of Mobile Private Networks

I also like this post on different names for private networks.

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Thursday 24 August 2023

Prof. Ted Rappaport Keynote at EuCNC & 6G Summit 2023 on 'Looking Towards the 6G Era - What we may expect, and why'

Prof. Ted Rappaport has featured a few times in our blog posts (see here and here). Today we look at his recent keynote at the EuCNC & 6G Summit 2023 on the topic 'Looking Towards the 6G Era - What we may expect, and why'. The abstract of the talk says:

Recent work has shown that the fundamentals of the radio propagation channel will enable mobile communications all the way to 900 GHz, offering bandwidths of tens of GHz. An amazing fact that is all but disregarded is that the three fundamental technological breakthroughs of 5G, namely millimeter wave technology, small cell densification, and massive multiple-input multiple-output (massive-MIMO) antenna systems, are paving the way for the next several decades of the wireless industry. This talk demonstrates how the 5G era will futureproof wireless networks as we enter the 6G era and beyond — an era of wireless cognition and human-style computing. In fewer than 20 years, wireless networks will carry information at the computation speed of the human brain. Yet, how will engineers ensure that we build these networks with sustainability and power efficiency in mind? This talk offers some solutions and promising areas of exploration to ensure the future 6G era is lightning fast yet kind to planet earth.

Recently I had a discussion about mmWave, sub-THz, THz, etc. This chart in the Tweet above is handy with deciphering the 5G/6G spectrum terminology.

Prof. Rappaport covered quite a few topics on spectrum above 100 GHz and made a strong case for mmWave and Terahertz. The mmWave adoption for 5G hasn't yet taken off so we will have to see how enthusiastic the industry is for even higher frequencies. The other keynotes from the conference (see references below) argued for cmWave as the mid-band for 6G. We will have to wait and see where all this discussion goes.

The talk is embedded below:

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Thursday 3 August 2023

Tutorial: A Quick Introduction to 3GPP

We recently made a beginners tutorial explaining the need for The 3rd Generation Partnership Project (3GPP), its working, structure and provides useful pointers to explore further. The video and slides are embedded below.

You can download the slides from here.

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Wednesday 12 July 2023

Small Data Transmission (SDT) in LTE and 5G NR

One of the features that was introduced part of 5G NR 3GPP Release 17 is known as Small Data Transmission (SDT). When small amount of data, in case of an IoT device, needs to be sent, there is no need to establish data radio bearers. The information can be sent as part of signalling message. A similar approach is available in case of 4G LTE. 

Quoting from Ofinno whitepaper 'Small Data Transmission: PHY/MAC', 

The SDT in the 3GPP simply refers to data transmission in an inactive state. Specifically, the SDT is a transmission for a short data burst in a connectionless state where a device does not need to establish and teardown connections when small amounts of data need to be sent.

In the 3GPP standards, the inactive state had not supported data transmission until Release 15. The 3GPP standards basically allowed the data transmission when ciphering and integrity protection are achieved during the connection establishment procedure. Therefore, the data transmission can occur after the successful completion of the establishment procedure between the device and network.

The problem arises as a device stays in the connected state for a short period of time and subsequently releases the connection once the small size data is sent. Generally, the device needs to perform multiple transmissions and receptions of control signals to initiate and maintain the connection with a network. As a payload size of the data is relatively smaller compared with the amounts of the control signals, making a connection for the small data transmission becomes more of a concern for both the network and the device due to the control signaling overhead.

The 3GPP has developed the SDT procedure to enable data transmission in the inactive state over the existing LTE and NR standards. The device initiates the SDT procedure by transmitting an RRC request message (e.g., SDT request message) and data in parallel instead of transmitting the data after the RRC request message processed by a network. Additional transmission and/or reception are optional. The device performs this SDT procedure without transition to the connected state (i.e., without making a connection to the network).

The SDT enables for the network to accept data transmission without signaling intensive bearer establishment and authentication procedure required for the RRC connection establishment or resume procedure. For example, in the SDT procedure, the device needs only one immediate transmission of a transport block (TB) that contains data and RRC request message. Furthermore, the device does not need to perform procedures (e.g., radio link monitoring) defined in the connected state since the RRC state is kept as the inactive state. This results in improving the battery life of the device by avoiding control signaling unnecessary for transmission of small size data.

The principle of the SDT is very simple. The network configures radio resources beforehand for the data transmission in the inactive state. For example, if the conditions to use the configured radio resources satisfy, the device transmits data and the RRC request message together via the configured radio resources. In the 3GPP standards, there are two types of the SDT depending on the ways to configure the radio resources: (1) SDT using a random access (RA) and (2) SDT using preconfigured radio resources. 

Figure 2 (top) illustrates different types of the SDT referred in 3GPP LTE and NR standards. The SDT using the random access in LTE and NR standards is referred to as an EDT (early data transmission) and RA-SDT (Random Access based SDT), respectively. For both the EDT and the RA-SDT, the device performs data transmission using shared radio resources of the random access procedure. Thus, the contention with other devices can occur over the access to the shared radio resources. The shared radio resources for the SDT are broadcast by system information and are configured as isolated from the one for a nonSDT RA procedure, i.e., the legacy RA procedure. On the other hands, the CG-SDT uses the preconfigured radio resources dedicated to the device. The SDT using the preconfigured radio resource is referred to as transmission via PUR (Preconfigured Uplink Resource) in the LTE standards. The NR standards refers the SDT using the preconfigured radio resource as CG-SDT (Configured Grant based SDT). The network configures the configuration parameters of the preconfigured radio resources when transiting the device in the connected state to the inactive state. For example, an RRC release message transmitted from the network for a connection release contains the configuration parameters of PUR or CG-SDT. No contention is expected for the SDT using the preconfigured radio resource since the configuration parameters are dedicated to the device. 

You can continue reading the details in whitepaper here. Ofinno has another whitepaper on this topic, 'Small Data Transmission (SDT): Protocol Aspects' here.

3GPP also recently published an article on this topic here. Quoting from the article:

With SDT it is possible for the device to send small amounts of data while remaining in the inactive state. Note that this idea resembles the early GSM systems where SMS messages where sent via the control signalling; that is, transferring small amounts of data while the mobile did not have a (voice) connection.

SDT is a procedure which allows data and/or signalling transmission while the device remains in inactive state without transitioning to connected state. SDT is enabled on a radio bearer basis and is initiated by the UE only if less than a configured amount of UL data awaits transmission across all radio bearers for which SDT is enabled. Otherwise the normal data transmission scheme is used.

With SDT the data is transmitted quickly on the allocated resource. The IoT device initiates the SDT procedure by transmitting an RRC request message and payload data in parallel, instead of the usual procedure where the data is transmitted after the RRC request message is processed by a network.

It is not only the speed and the reduced size of the transmitted data which make SDT such a suitable process for IoT devices. Since the device stays in the inactive state, it does not have to perform many tasks associated with the active state. This further improves the battery life of the IoT device. Additional transmission and/or reception are optional.

There are two ways of performing SDT:

  1. via random access (RA-SDT)
  2. via preconfigured radio resources (CG-SDT)

Random Access SDT

With RA-SDT, the IoT device does not have a dedicated radio resource, and it is possible that the random access message clashes with similar RA-SDT random access messages from other IoT devices. The device gets to know the radio resources for the RA procedure from system information messages, in a similar way to non RA-SDT devices. However, the RA radio resources for SDT and non SDT devices are kept separate; that is, these device types do not interfere with each other in random access

The RA-SDT procedure can be a two-step or a four-step random access procedure. In two-step procedure the payload data is already sent with the initial random access message, whereas in four-step procedure the device first performs contention resolution with the random access request - random access response message pair, and then sends the UL payload with RRC Resume Request. The procedure may continue with further uplink and downlink small data transmissions, and then it is terminated with an RRC Release from the network.

Below are the signalling diagrams for both two-step and four-step RA-SDT procedures. Note that in both cases the UE stays in the RRC inactive state during the whole process.

Configured Grant SDT

For CG-SDT, the radio resources are allocated periodically based on the estimation of the UE’s traffic requirements. This uplink scheduling method is called Configured Grant (CG). With CG-SDT there will be no message clashes with other IoT devices since the radio resources are dedicated for each device. The resource allocation is signalled to the IoT device by the network when the device leaves the connected state.

If the amount of data in the UE's tx buffer is larger than a defined limit, then the data transmission is done using the normal non-SDT procedure.

For SDT process, the device selects the CG-SDT as the SDT type if the resources for the CG-SDT are configured on the selected uplink carrier. If the resources for the CG-SDT are unavailable or invalid, the RA-SDT or the non-SDT RA procedure will be chosen if those are configured. If no SDT type configuration is available then a normal non-SDT data transmission is performed.

With IoT devices proliferating, it makes sense to optimise data transfer and anything else that will reduce the power consumption and let the battery in the devices last for much longer.

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Wednesday 21 June 2023

3GPP TSG RAN and TSG SA Release-19 Workshop Summary

3GPP recently announced the milestone of reaching 100th plenaries of the three Technical Specification Groups (TSGs) in 3GPP which took place in Taipei last week. If you are unsure what TSGs are, we recently made a tutorial of 3GPP, available here.

During the plenary TSG SA and TSG RAN held workshops on Release 19. The top level link for RAN workshop is here while that for SA is here. SA also has HTML link of the documents here.

The slide above is from the RAN chair's summary provides list of topics that were discussed. The following is the executive summary from the draft workshop report:

The 3GPP TSG RAN Rel-19 face-to-face workshop was held June 15 - June 16, 2023 in Taipei hosted by TAICS (Taiwan Association of Information and Communication Standards) and MediaTek with 174 participants (see Annex A) and 491 Tdocs (see Annex B). A GotoWebinar conference call was carried out during the whole workshop to display discussed documents and to allow listen & talk access for people joining remotely.

The workshop agenda was provided in RWS-230001 and split into 3 main parts:

  • High-level overview proposals for Rel-19: 18 Tdocs handled, 46 not treated, 1 in the end endorsed (RP-230488)
  • Specific RAN1/2/3-led Rel-19 topics: 29 Tdocs handled, 369 not treated
  • RAN4-led Rel-19 topics (for information only): 20 not treated

Note: High-level overview proposals for Rel-19 and RAN4-led Rel-19 topics had the restriction of maximum one contribution led per company.

Some guidance about the workshop was provided on the RAN email reflector on 28.04.23 and 02.05.23.

Time plan versions of the workshop were provided on 02.05.23, 11.06.23 and on 15.06.23.

Workshop inputs were possible from 28.04.23 until the submission deadline 31.05.23 9pm UTC.

(Late Tdoc requests as well as revisions of Tdocs after the Tdoc request deadline 30.05.23 9pm UTC were avoided in order to not complicate the Tdoc handling, like quotas for AI 4 and 6, preparations of the workshop in parallel to RAN #100 and preparations of the summary etc.)

Originally, Thursday 15.06.23 and Friday 16.06.23 morning were planned for presentations of a limited set of 47 workshop contributions (selected by the RAN chair trying to achieve a fair coverage of the topics and interests and taking into account that there were many more inputs that can be handled in a 2 days workshop) and Friday afternoon was reserved for the discussion of a summary of the RAN chair (in RWS-230488). Note: Since the presentation part went faster and the Friday lunch break was skipped, the workshop ended on Friday afternoon earlier than originally planned.

Finally, the RAN chair's summary in RWS-230488 was endorsed indicating the motivations and handling of the workshop, the Rel-19 timeline and load plans and the management and categorization of topics.

TSG SA didn't have a summary slide but SWS-230002, output of drafting session on Consolidated SA WG2 Rel-19 Work, listed the following topics:

  • Satellite Architecure Enhancements
  • XRM Enhancements and Metaverse
  • AI/ML enhancements
  • Multi-access (Dual 3GPP + ATSSS Enh)
  • Integrated Sensing and Communication
  • Ambient IoT
  • Energy Efficiency / Energy Saving as a Service
  • IMS and NG_RTC enhancements
  • Edge Computing Enhancements
  • Proximity Services enhancements 
  • TSC/URLLC/TRS enhancements 
  • Network Sharing 
  • User identities + identification of device behind RG/AP
  • 5G Femto 
  • UAS enhancements 
  • VMR Enhancements 
  • UPEAS Enhancements 

Fattesinh Deshmukh has a summary of 3GPP RAN Rel-19 Workshop on LinkedIn here. Nokia has their summary of the workshop here.

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Wednesday 31 May 2023

New 5G NTN Spectrum Bands in FR1 and FR2

Release-17 includes two new FR1 bands for NTN; n255 (a.k.a. NTN 1.6GHz) and n256 (a.k.a. NTN 2GHz). The picture is from a slide in Rohde & Schwarz presentation available here. Quoting from an article by Reiner Stuhlfauth, Technology Manager Wireless, Rohde & Schwarz:

Currently, several frequency ranges are being discussed within 3GPP for NTN. Some are in the FR1 legacy spectrum, and some beyond 10 GHz and FR2. The current FR1 bands discussed for NTN are:

  • The S-band frequencies from 1980 to 2010 MHz in uplink (UL) direction and from 2170 to 2200 MHz in downlink (DL) direction (Band n256).
  • The L-band frequencies from 1525 to 1559 MHz DL together with 1626.5 to 1660.5 MHz for the UL (Band n255).1

These frequency ranges have lower path attenuation, and they’re already used in legacy communications. Thus, components are available now, but the bands are very crowded, and the usable bandwidth is restricted. Current maximum bandwidth is 20 MHz with up to 40-MHz overall bandwidth envisaged in the future [TR 38.811].

As far as long-term NTN spectrum use is concerned, 3GPP is discussing NR-NTN above 10 GHz. The Ka-band is the highest-priority band with uplinks between 17.7 and 20.2 GHz and downlinks between 27.5 and 30 GHz, based on ITU information regarding satellite communications frequency use.2 Among current FR2 challenges, one is that some of the discussed bands fall into the spectrum gap between FR1 and FR2 and that NTN frequencies will use FDD duplex mode due to the long roundtrip time.

Worth highlighting again that the bands above, including n510, n511 and n512 are all FDD bands due to the long round trip times.

The latest issue of 3GPP highlight magazine has an article on NTN as well. Quoting from the article:

The NTN standard completed as part of 3GPP Release 17 defines key enhancements to support satellite networks for two types of radio protocols/interfaces:

  • 5G NR radio interface family also known as NR-NTN
  • 4G NB-IoT & eMTC radio interfaces family known as IoT-NTN

These critical enhancements including adaptation for satellite latency and doppler effects have been carefully defined to support a wide range of satellite network deployment scenarios and orbits (i.e., LEO, MEO and GEO), terminal types (handheld, IoT, vehicle mounted), frequency bands, beam types (Earth fixed/Earth moving) and sizes. The NTN standard also addresses mobility procedures across both terrestrial and non-terrestrial network components. Release 17 further includes Radio Frequency and Radio Resource Management specifications for terminals and satellite access nodes operating in two FR1 frequency ranges allocated to Mobile Satellite Services (i.e., n255 and n256).

You can read it here.

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Tuesday 23 May 2023

Top 10 New (2022) Security Standards That You Need to Know About!

I had been meaning to add this session to the blog for a while. Some security researchers may find these useful. 

At RSA Conference 2022, Bret Jordan, CTO, Emerging Technologies, Broadcom and Kirsty Paine, Advisor - Technology & Innovation, EMEA, Splunk Inc. presented a talk covering what they described as the most important, interesting and impactful technical standards, hot off the press and so 2022. From the internet and all its things, to the latest cybersecurity defenses, including 5G updates and more acronyms than one can shake a stick at. 

The video is embedded below and the slides are available here.

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Wednesday 3 May 2023

Qualcomm Webinar on 'Realizing mission-critical industrial automation with 5G'

Private 5G networks have immense potential to transform industries by improving flexibility within the shop floor of the industries. Industrial 5G networks hold the promise to transform mission-critical industrial automation by using the built-in 5G features of higher bandwidth, lower latency, greater reliability, and improved security.

Some of the ways in which Industrial 5G (I5G) networks will help transform mission-critical industrial networks using automation include:

  • Enhanced Communication: I5G networks will offer faster and more reliable communication between machines, sensors, and other devices. This will lead to better synchronization, increased efficiency, and reduced downtime in industrial processes.
  • High-Quality Video: I5G networks will provide high-quality video streaming, enabling real-time monitoring of industrial processes. This will be particularly useful in applications such as remote inspections, quality control, and process optimization.
  • Edge Computing: I5G networks will support edge computing, that will enable processing of data close to where it is generated. This will help to keep latency to a minimum thereby improve response times and making it possible to perform critical tasks in real-time.
  • Improved Security: I5G networks will provide improved security features along with network slicing, which will enable the creation of secure virtual networks for specific applications or users. This will in-turn help to protect against cyberattacks and ensure the integrity of data.
  • Reduced Downtime: I5G networks will help to reduce downtime by providing real-time monitoring and predictive maintenance capabilities. This will allow identification of potential problems before they cause downtime thereby enabling proactive maintenance and repairs.

Overall, I5G networks have the potential and the capability to significantly improve mission-critical industrial automation by providing faster, more reliable, and secure communication, enabling real-time monitoring and control, and reducing downtime through predictive maintenance capabilities.

In addition, Private/Industrial 5G will help with Time-Sensitive Networking (TSN) by providing a highly reliable and low-latency wireless communication network that can support real-time industrial control and automation applications. TSN is a set of IEEE standards that enable time-critical data to be transmitted over Ethernet networks with very low latency and high reliability.

I5G networks provide a wireless alternative to wired Ethernet networks for TSN applications, which can be advantageous in environments where deploying Ethernet cabling is difficult or costly. With I5G, TSN traffic can be prioritized and transmitted over the network with low latency and high reliability, which is critical for industrial automation and control applications that require precise timing and synchronization.

Moreover, I5G networks can be deployed with network slicing capabilities, allowing for the creation of multiple virtual networks with different performance characteristics tailored to specific applications or user groups. This means that TSN traffic can be isolated and prioritized over other types of traffic, ensuring that critical data is always transmitted with the highest priority and reliability.

Last year, Qualcomm hosted a webinar on 'Realizing mission-critical industrial automation with 5G'. The webinar is embedded below:

Here is the summary of what the webinar includes:

Manufacturers seeking better operational efficiencies, with reduced downtime and higher yield, are at the leading edge of the Industry 4.0 transformation. With mobile system components and reliable wireless connectivity between them, flexible manufacturing systems can be reconfigured quickly for new tasks, to troubleshoot issues, or in response to shifts in supply and demand. 

5G connectivity enables flexibility in demanding industrial environments with key capabilities such as ultra-reliable wireless connectivity, wireless Ethernet, time-sensitive networking (TSN), and positioning. There is a long history of R&D collaboration between Bosch Rexroth and Qualcomm Technologies for the effective application of these 5G capabilities to industrial automation use cases. At the Robert Bosch Elektronik GmbH factory in Salzgitter, Germany, this collaboration has reached new heights by demonstrating time-synchronized control of an industrial robot, and remote positioning of an automated guided vehicle (AGV) over a live, ultra-reliable 5G private network.

Watch the session to learn how:

  • Qualcomm Technologies and Bosch Rexroth are collaborating to accelerate the Industry 4.0 transformation
  • 5G technologies deliver key capabilities for mission-critical industrial automation
  • Distributed control solutions can work effectively across 5G TSN networks
  • A single 5G technology platform solves connectivity and positioning needs for flexible manufacturing

The video is also available on Qualcomm site here and the slides are here.

A shorter video looking behind the tech to see how Qualcomm and Bosch are partnering to enable mission-critical industrial automation over a 5G private network is as follows:

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