Self-backhauling: Integrated access and backhaul links for 5G

One of the items that was proposed during the 3GPP RAN Plenary #75 held in Dubrovnik, Croatia, was Study on Integrated Access and Backhaul for NR (NR = New Radio). RP-17148 provides more details as follows:

One of the potential technologies targeted to enable future cellular network deployment scenarios and applications is the support for wireless backhaul and relay links enabling flexible and very dense deployment of NR cells without the need for densifying the transport network proportionately. 

Due to the expected larger bandwidth available for NR compared to LTE (e.g. mmWave spectrum) along with the native deployment of massive MIMO or multi-beam systems in NR creates an opportunity to develop and deploy integrated access and backhaul links. This may allow easier deployment of a dense network of self-backhauled NR cells in a more integrated manner by building upon many of the control and data channels/procedures defined for providing access to UEs. An example illustration of a network with such integrated access and backhaul links is shown in Figure 1, where relay nodes (rTRPs) can multiplex access and backhaul links in time, frequency, or space (e.g. beam-based operation).

The operation of the different links may be on the same or different frequencies (also termed ‘in-band’ and ‘out-band’ relays). While efficient support of out-band relays is important for some NR deployment scenarios, it is critically important to understand the requirements of in-band operation which imply tighter interworking with the access links operating on the same frequency to accommodate duplex constraints and avoid/mitigate interference. 

In addition, operating NR systems in mmWave spectrum presents some unique challenges including experiencing severe short-term blocking that cannot be readily mitigated by present RRC-based handover mechanisms due to the larger time-scales required for completion of the procedures compared to short-term blocking. Overcoming short-term blocking in mmWave systems may require fast L2-based switching between rTRPs, much like dynamic point selection, or modified L3-based solutions. The above described need to mitigate short-term blocking for NR operation in mmWave spectrum along with the desire for easier deployment of self-backhauled NR cells creates a need for the development of an integrated framework that allows fast switching of access and backhaul links. Over-the-air (OTA) coordination between rTRPs can also be considered to mitigate interference and support end-to-end route selection and optimization.

The benefits of integrated access and backhaul (IAB) are crucial during network rollout and the initial network growth phase. To leverage these benefits, IAB needs to be available when NR rollout occurs. Consequently, postponing IAB-related work to a later stage may have adverse impact on the timely deployment of NR access.

There is also an interesting presentation on this topic from Interdigital on the 5G Crosshaul group here. I found the following points worth noting:

• This will create a new type of interference (access-backhaul interference) to mitigate and will require sophisticated (complex) scheduling of the channel resources (across two domains, access and backhaul).
• One of the main drivers is Small cells densification calling for cost-effective and low latency backhauling
• The goal would be to maximize efficiency through joint optimization/integration of access and backhaul resources
• The existing approach of Fronthaul using CPRI will not scale for 5G, self-backhaul may be an alternative in the shape of wireless fronthaul

Let me know what you think.

Related Links:

• Backhauling problems driving up deployment costs?

Latest on 5G Spectrum - March 2017

In an earlier post I mentioned that there will be three different types of spectrum that would be needed for 5G; coverage layer, capacity layer and high throughput layer. There is now a consensus within the industry for this approach.

In a 5G seminar, back in Jan, there were a few speakers who felt that there is an informal agreement about the frequencies that will be used. One such slide from Ofcom could be seen in the picture above. Ofcom has also recently released a report expanding on this further.

Analysys Mason has nicely summarized the bands suggested by Ofcom and possibly available in the UK for 5G in the picture above.

Global mobile Suppliers Association (GSA) has also nicely summarised the bands under investigations and trials as follows:

Coverage Layer: 600 MHz, 700 MHz, 800 MHz, 900 MHz, 1.5 GHz, 2.1 GHz, 2.3 GHz and 2.6 GHz

Capacity Layer:

Europe                     3400 – 3800 MHz (awarding trial licenses)

China                       3300 – 3600 MHz (ongoing trial), 4400 – 4500 MHz, 4800 – 4990 MHz

Japan                       3600 – 4200 MHz and 4400-4900 MHz

Korea                       3400 – 3700 MHz

USA                          3100 – 3550 MHz (and 3700 – 4200 MHz)

High Throughput Layer:

USA:      27.5 – 28.35 GHz and 37 – 40 GHz pre-commercial deployments in 2018

Korea:   26.5 – 29.5 GHz trials in 2018 and commercial deployments in 2019

Japan:   27.5 – 28.28 GHz trials planned from 2017 and potentially commercial deployments in 2020

China:    Focusing on 24.25 – 27.5 GHz and 37 – 43.5 GHz studies

Sweden: 26.5 – 27.5 GHz awarding trial licenses for use in 2018 and onwards

EU:        24.25 – 27.5 GHz for commercial deployments from 2020

Finally, as a reminder, list of bands originally approved for IMT-2020 (5G) as follows:

Another potential band, not being mentioned above is the 66-76GHz spectrum. This band is adjacent to the 60 GHz Wi-Fi (57 GHz - 66 GHz). Lessons learned from that band can be applied to the 5G band too.

Related links:

• How much spectrum would 5G need?
• IMT-2020 (5G) Requirements
• Ofcom: Update on 5G spectrum in the UK - Feb 2017 [PDF]
• Analysys Mason: A spectrum roadmap towards 5G - Mar 2017
• GSA: 5G Spectrum Bands - Feb 2017

Satellite Industry is Gearing up for The Next Revolution in Communications

Source: Intelsat

I have been talking about the role of satellites in future communications on my blog and various industry fora. While most of the telecom industry is focused on 5G, it’s good to see that the satellite industry is getting ready for the next revolution.

Source: New York Times

Masayoshi Son, chief executive of SoftBank has made it his mission to merge satellite operators Intelsat and OneWeb. While on the surface they may seem as competitors, in reality they complement each other. Intelsat operates geostationary (GEO) satellites while OneWeb is building low earth orbit (LEO) satellites. They both serve overlapping but different purposes and it makes sense for them to work together. LEO satellites which are roughly at 1200km have far lower latency than compared to GEO satellites that are 36,000km away. On the other hand LEO satellites do not appear stationary unlike GEO satellites.

We in CW are already aware of Masayoshi Son’s ambition and vision. Last year Softbank acquired ARM for approximately £24 billion. In a recent keynote delivered at the Mobile World Congress 2017 (#MWC17), Son explained his vision and reasoning for this purchase. In fact he mentioned that he has a 30 year vision which is why he thinks ‘cell towers from space’ are the next step in evolution. While he refers to them as fiber from the space, I wouldn’t go that far in comparison but do admit they have the potential to deliver high speed connectivity anywhere on earth.

The most obvious application of high speed connectivity ubiquitously available anywhere on earth are connected cars. While there is Wi-Fi to provide connectivity and software updates when parked at home, it will be complemented by mobile connectivity within the cities and the major roads. What is missing is anywhere and everywhere connectivity that the satellites can bring.

The big barrier for satellite connectivity in the cars had been the need for satellite dish mounted on the top of a car roof. Kymeta, an innovative company based in Washington, USA has been trying for years to solve this problem. In May, they will start selling  their “lightweight flat-panel antennas, meant to bring fast satellite-transmitted internet connections to cars, trains and boats”.

Source: Seattle Times

Kymeta is partnering with Toyota and Intelsat to bring a complete solution for future connectivity in the cars. They are not the only ones, there are other similar interesting projects ongoing in many different parts of the world.

The telecom industry cannot ignore satellite communications forever. Satellites have already proved themselves beyond doubt in broadcasting, navigation, earth observation, etc. It’s just a matter of time before they prove their while in communications as well.

Originally Posted on CW Blog here.

IMT-2020 (5G) Requirements

ITU has just agreed on key 5G performance requirements for IMT-2020. A new draft report ITU-R M.[IMT-2020.TECH PERF REQ] is expected to be finally approved by  ITU-R Study Group 5 at its next meeting in November 2017. The press release says "5G mobile systems to provide lightning speed, ultra-reliable communications for broadband and IoT"

The following is from the ITU draft report:

The key minimum technical performance requirements defined in this document are for the purpose of consistent definition, specification, and evaluation of the candidate IMT-2020 radio interface technologies (RITs)/Set of radio interface technologies (SRIT) in conjunction with the development of ITU-R Recommendations and Reports, such as the detailed specifications of IMT-2020. The intent of these requirements is to ensure that IMT-2020 technologies are able to fulfil the objectives of IMT-2020 and to set a specific level of performance that each proposed RIT/SRIT needs to achieve in order to be considered by ITU-R for IMT-2020.


Peak data rate: Peak data rate is the maximum achievable data rate under ideal conditions (in bit/s), which is the received data bits assuming error-free conditions assignable to a single mobile station, when all assignable radio resources for the corresponding link direction are utilized (i.e., excluding radio resources that are used for physical layer synchronization, reference signals or pilots, guard bands and guard times). 

This requirement is defined for the purpose of evaluation in the eMBB usage scenario. 
The minimum requirements for peak data rate are as follows:
– Downlink peak data rate is 20 Gbit/s.
– Uplink peak data rate is 10 Gbit/s.


Peak spectral efficiency: Peak spectral efficiency is the maximum data rate under ideal conditions normalised by channel bandwidth (in bit/s/Hz), where the maximum data rate is the received data bits assuming error-free conditions assignable to a single mobile station, when all assignable radio resources for the corresponding link direction are utilized (i.e. excluding radio resources that are used for physical layer synchronization, reference signals or pilots, guard bands and guard times).

This requirement is defined for the purpose of evaluation in the eMBB usage scenario.
The minimum requirements for peak spectral efficiencies are as follows: 
– Downlink peak spectral efficiency is 30 bit/s/Hz.
– Uplink peak spectral efficiency is 15 bit/s/Hz.


User experienced data rate: User experienced data rate is the 5% point of the cumulative distribution function (CDF) of the user throughput. User throughput (during active time) is defined as the number of correctly received bits, i.e. the number of bits contained in the service data units (SDUs) delivered to Layer 3, over a certain period of time.

This requirement is defined for the purpose of evaluation in the related eMBB test environment.
The target values for the user experienced data rate are as follows in the Dense Urban – eMBB test environment: 
– Downlink user experienced data rate is 100 Mbit/s. 
– Uplink user experienced data rate is 50 Mbit/s. 


5th percentile user spectral efficiency: The 5th percentile user spectral efficiency is the 5% point of the CDF of the normalized user throughput. The normalized user throughput is defined as the number of correctly received bits, i.e., the number of bits contained in the SDUs delivered to Layer 3, over a certain period of time, divided by the channel bandwidth and is measured in bit/s/Hz. 

This requirement is defined for the purpose of evaluation in the eMBB usage scenario.
– Indoor Hotspot – eMBB - Downlink: 0.3 bit/s/Hz Uplink: 0.21 bit/s/Hz
– Dense Urban – eMBB - Downlink: 0.225 bit/s/Hz Uplink: 0.15 bit/s/Hz
– Rural – eMBB - Downlink: 0.12 bit/s/Hz Uplink: 0.045 bit/s/Hz


Average spectral efficiency: Average spectral efficiency  is the aggregate throughput of all users (the number of correctly received bits, i.e. the number of bits contained in the SDUs delivered to Layer 3, over a certain period of time) divided by the channel bandwidth of a specific band divided by the number of TRxPs and is measured in bit/s/Hz/TRxP.

This requirement is defined for the purpose of evaluation in the eMBB usage scenario.
– Indoor Hotspot – eMBB - Downlink: 9 bit/s/Hz/TRxP Uplink: 6.75 bit/s/Hz/TRxP
– Dense Urban – eMBB - Downlink: 7.8 bit/s/Hz/TRxP Uplink: 5.4 bit/s/Hz/TRxP
– Rural – eMBB - Downlink: 3.3 bit/s/Hz/TRxP Uplink: 1.6 bit/s/Hz/TRxP


Area traffic capacity: Area traffic capacity is the total traffic throughput served per geographic area (in Mbit/s/m2). The throughput is the number of correctly received bits, i.e. the number of bits contained in the SDUs delivered to Layer 3, over a certain period of time.

This requirement is defined for the purpose of evaluation in the related eMBB test environment.
The target value for Area traffic capacity in downlink is 10 Mbit/s/m2 in the Indoor Hotspot – eMBB test environment.


User plane latency: User plane latency is the contribution of the radio network to the time from when the source sends a packet to when the destination receives it (in ms). It is defined as the one-way time it takes to successfully deliver an application layer packet/message from the radio protocol layer 2/3 SDU ingress point to the radio protocol layer 2/3 SDU egress point of the radio interface in either uplink or downlink in the network for a given service in unloaded conditions, assuming the mobile station is in the active state. 
This requirement is defined for the purpose of evaluation in the eMBB and URLLC usage scenarios.
The minimum requirements for user plane latency are
– 4 ms for eMBB
– 1 ms for URLLC 
assuming unloaded conditions (i.e., a single user) for small IP packets (e.g., 0 byte payload + IP header), for both downlink and uplink.


Control plane latency: Control plane latency refers to the transition time from a most “battery efficient” state (e.g. Idle state) to the start of continuous data transfer (e.g. Active state).
This requirement is defined for the purpose of evaluation in the eMBB and URLLC usage scenarios.
The minimum requirement for control plane latency is 20 ms. Proponents are encouraged to consider lower control plane latency, e.g. 10 ms.


Connection density: Connection density is the total number of devices fulfilling a specific quality of service (QoS) per unit area (per km2).

This requirement is defined for the purpose of evaluation in the mMTC usage scenario.
The minimum requirement for connection density is 1 000 000 devices per km2.


Energy efficiency: Network energy efficiency is the capability of a RIT/SRIT to minimize the radio access network energy consumption in relation to the traffic capacity provided. Device energy efficiency is the capability of the RIT/SRIT to minimize the power consumed by the device modem in relation to the traffic characteristics. 
Energy efficiency of the network and the device can relate to the support for the following two aspects:
a) Efficient data transmission in a loaded case;
b) Low energy consumption when there is no data.
Efficient data transmission in a loaded case is demonstrated by the average spectral efficiency 

This requirement is defined for the purpose of evaluation in the eMBB usage scenario.
The RIT/SRIT shall have the capability to support a high sleep ratio and long sleep duration. Proponents are encouraged to describe other mechanisms of the RIT/SRIT that improve the support of energy efficient operation for both network and device.


Reliability: Reliability relates to the capability of transmitting a given amount of traffic within a predetermined time duration with high success probability

This requirement is defined for the purpose of evaluation in the URLLC usage scenario. 
The minimum requirement for the reliability is 1-10-5 success probability of transmitting a layer 2 PDU (protocol data unit) of 32 bytes within 1 ms in channel quality of coverage edge for the Urban Macro-URLLC test environment, assuming small application data (e.g. 20 bytes application data + protocol overhead). 
Proponents are encouraged to consider larger packet sizes, e.g. layer 2 PDU size of up to 100 bytes.


Mobility: Mobility is the maximum mobile station speed at which a defined QoS can be achieved (in km/h).

The following classes of mobility are defined:
– Stationary: 0 km/h
– Pedestrian: 0 km/h to 10 km/h
– Vehicular: 10 km/h to 120 km/h
– High speed vehicular: 120 km/h to 500 km/h

Mobility classes supported:
Indoor Hotspot – eMBB: Stationary, Pedestrian
Dense Urban – eMBB: Stationary, Pedestrian, Vehicular (up to 30 km/h)
Rural – eMBB: Pedestrian, Vehicular, High speed vehicular 


Mobility interruption time: Mobility interruption time is the shortest time duration supported by the system during which a user terminal cannot exchange user plane packets with any base station during transitions.

This requirement is defined for the purpose of evaluation in the eMBB and URLLC usage scenarios.
The minimum requirement for mobility interruption time is 0 ms.


Bandwidth: Bandwidth is the maximum aggregated system bandwidth. The bandwidth may be supported by single or multiple radio frequency (RF) carriers. The bandwidth capability of the RIT/SRIT is defined for the purpose of IMT-2020 evaluation.

The requirement for bandwidth is at least 100 MHz. 
The RIT/SRIT shall support bandwidths up to 1 GHz for operation in higher frequency bands (e.g. above 6 GHz). 

In case you missed, a 5G logo has also been released by 3GPP

Related posts:

• Some more thoughts on 5G
• 5G Network Architecture and Design Update - Jan 2017
• 5G New Radio (NR), Architecture options and migration from LTE
• LTE-Advanced Pro (a.k.a. 4.5G)
• Gigabit LTE?
• 4G / LTE by stealth

What's '5G' in one word for you?

Last month in the IET 'Towards 5G Mobile Technology – Vision to Reality' seminar, Dr. Mike Short threw out a challenge to all speakers to come up with one word to describe 5G technology. The speakers came up with the following 'one words':

• Professor Mischa Dohler, Centre for Telecommunications Research, King's College London, UK - Skills
• Professor Maziar Nekovee, Professor,University of Sussex UK - Transformative or Magic
• Professor Andy Sutton, Principal Network Architect, BT, UK - Opportunity
• Professor Mark Beach, University of Bristol, UK - Networked-Society
• Mark Barrett, CMO, Bluwireless, UK - Gigabit
• Dr Nishanth Sastry, Centre for Telecommunications Research, Kings’ College London, UK - Flexibility or Efficiency
• Dr Reiner Hoppe, Developer Electromagnetic Solutions, Altair - Radio
• Professor Klaus Moessner, 5G Innovation Centre, University of Surrey, UK - Capacity
• Joe Butler, Director of Technology, Ofcom, UK - Ubiquity
• Dr Deeph Chana, Deputy Director, Institute for Security Science and Technology, Imperial College London, UK - Accessibility

What is your one word to describe 5G? Please add in comments. I welcome critical suggestions too :-)

Anyway, for anyone interested, the following story summarises the event:

This section contained story from Storify. Storify was shut down on May 16, 2018 and as a result the story was lost. An archived version of the story can be seen on wayback machine here.

Related links:

• 5G Network Architecture and Design Update - Jan 2017
• Videos from IET TV: Towards 5G Mobile Technology – Vision to Reality

5G Network Architecture and Design Update - Jan 2017

Andy Sutton, Principal Network Architect at BT recently talked about the architecture update from the Dec 2016 3GPP meeting. The slides and the video is embedded below.

5G Network Architecture and Design from 3G4G

You can see all the presentations from IET event 'Towards 5G Mobile Technology – Vision to Reality' here.

Eiko Seidel recently also wrote an update from 3GPP 5G Adhoc regarding RAN Internal Functional Split. You can read that report here.

Related posts:

• 5G New Radio (NR), Architecture options and migration from LTE
• 5G Fronthaul: Crosshaul & XHaul
• Some more thoughts on 5G
• Verizon's 5G Standard
• 5G Network Architecture Options - Video

Augmented / Virtual Reality Requirements for 5G

Ever wondered whether 5G would be good enough for Augmented and Virtual Reality or will we need to wait for 6G? Some researchers are trying to identify the AR / VR requirements, challenges from a mobile network point of view and possible options to solve these challenges. They have recently published a research paper on this topic.

Here is a summary of some of the interesting things I found in this paper:

• Humans process nearly 5.2 gigabits per second of sound and light.
• Without moving the head, our eyes can mechanically shift across a field of view of at least 150 degrees horizontally (i.e., 30:000 pixels) and 120 degrees vertically (i.e., 24:000 pixels).
• The human eye can perceive much faster motion (150 frames per second). For sports, games, science and other high-speed immersive experiences, video rates of 60 or even 120 frames per second are needed to avoid motion blur and disorientation.
• 5.2 gigabits per second of network throughput (if not more) is needed.
• At today’s 4K resolution, 30 frames per second and 24 bits per pixel, and using a 300 : 1 compression ratio, yields 300 megabits per second of imagery. That is more than 10x the typical requirement for a high-quality 4K movie experience.
• 5G network architectures are being designed to move the post-processing at the network edge so that processors at the edge and the client display devices (VR goggles, smart TVs, tablets and phones) carry out advanced image processing to stitch camera feeds into dramatic effects.
• In order to tackle these grand challenges, the 5G network architecture (radio access network (RAN), Edge and Core) will need to be much smarter than ever before by adaptively and dynamically making use of concepts such as software defined networking (SDN), network function virtualization (NFV) and network slicing, to mention a few facilitating a more flexible allocating resources (resource blocks (RBs), access point, storage, memory, computing, etc.) to meet these demands.
• Immersive technology will require massive improvements in terms of bandwidth, latency and reliablility. Current remotereality prototype requires 100-to-200Mbps for a one-way immersive experience. While MirrorSys uses a single 8K, estimates about photo-realistic VR will require two 16K x 16K screens (one to each eye).
• Latency is the other big issue in addition to reliability. With an augmented reality headset, for example, real-life visual and auditory information has to be taken in through the camera and sent to the fog/cloud for processing, with digital information sent back to be precisely overlaid onto the real-world environment, and all this has to happen in less time than it takes for humans to start noticing lag (no more than 13ms). Factoring in the much needed high reliability criteria on top of these bandwidth and delay requirements clearly indicates the need for interactions between several research disciplines.

These key research directions and scientific challenges are summarized in Fig. 3 (above), and discussed in the paper. I advice you to read it here.

Related posts:

• Have researchers moved on past 5G on to 6G Wireless?
• Quantum Technology and Future Telecommunications
• 'Mobile Edge Computing' (MEC) or 'Fog Computing' (fogging) and 5G & IoT

5G, Hacking & Security

It looks like devices that are not manufactures with security and privacy in mind are going to be the weakest link in future network security problems. I am sure you have probably read about how hacked cameras and routers enabled a Mirai botnet to take out major websites in October. Since then, there has been no shortage of how IoT devices could be hacked. In fact the one I really liked was 'Researchers hack Philips Hue lights via a drone; IoT worm could cause city blackout' 😏.

Enter 5G and the problem could be be made much worse. With high speed data transfer and signalling, these devices can create an instantaneous attack on a very large scale and generating signalling storm that can take a network down in no time.

Giuseppe TARGIA, Nokia presented an excellent summary of some of these issues at the iDate Digiworld Summit 2016. His talk is embedded below:



You can check out many interesting presentations from the iDate Digiworld Summit 2016 on Youtube and Slideshare.

Related posts:

• Three Presentations on 5G Security
• New whitepaper on Narrowband Internet of Things
• 5G New Radio (NR), Architecture options and migration from LTE
• M2M vs IoT
• Some more thoughts on 5G
• LTE, 5G and V2X
• 5G, Debates, Predictions and Stories

5G, Debates, Predictions and Stories

This post contains summary of three interesting events that took place recently.

CW (Cambridge Wireless) organised a couple of debates on 5G as can be seen from the topics above. Below is the summary video and twitter discussion summary/story.

The second story is from 'The Great Telco Debate 2016' organised by TM forum

I am not embedding the story but for anyone interested, they can read the twitter summary here: https://storify.com/zahidtg/the-great-telco-debate-2016

Finally, it was 'Predictions: 2017 and Beyond', organised by CCS Insight. The whole twitter discussion is embedded below.

Verizon's 5G Standard

Earlier this year I wrote a Linkedin post on how operators are setting a timetable for 5G (5G: Mine is bigger than yours) and recently Dean Bubley of Disruptive Analysis wrote a similar kind of post also on Linkedin with a bit more detail (5G: Industry Politics, Use-Cases & a Realistic Timeline)

Some of you may be unaware that the US operator Verizon has formed 'Verizon 5G Technology Forum' (V5GTF) with the intention of developing the first set of standards that can also influence the direction of 3GPP standardization and also provide an early mover advantage to itself and its partners.

The following from Light Reading news summarizes the situation well:

Verizon has posted its second round of work with its partners on a 5G specification. The first round was around the 5G radio specification; this time the work has been on the mechanics of connecting to the network. The operator has been working on the specification with Cisco Systems Inc., Ericsson AB, Intel Corp., LG Electronics Inc., Nokia Corp., Qualcomm Inc. and Samsung Corp. via the 5G Technology Forum (V5GTF) it formed late in 2015.

Sanyogita Shamsunder, director of strategy at Verizon, says that the specification is "75% to 80% there" at least for a "fixed wireless use case." Verizon is aiming for a "friendly, pre-commercial launch" of a fixed wireless pilot in 2017, Koeppe notes.

Before we go further, lets see this excellent video by R&S wherein Andreas Roessler explains what Verizon is up to:



Verizon and SKT are both trying to be the 5G leaders and trying to roll out a pre-standard 5G whenever they can. In fact Qualcomm recently released a 28 GHz modem that will be used in separate pre-standard 5G cellular trials by Verizon and Korea Telecom

Introducing #Snapdragon X50, our first #5G modem. https://t.co/MBmAS86WaH pic.twitter.com/ewOdm4OVzE

— Qualcomm (@Qualcomm) October 18, 2016

Quoting from the EE times article:

The Snapdragon X50 delivers 5 Gbits/second downlinks and multiple gigabit uplinks for mobile and fixed-wireless networks. It uses a separate LTE connection as an anchor for control signals while the 28 GHz link delivers the higher data rates over distances of tens to hundreds of meters.

The X50 uses eight 100 MHz channels, a 2x2 MIMO antenna array, adaptive beamforming techniques and 64 QAM to achieve a 90 dB link budget. It works in conjunction with Qualcomm’s SDR05x mmWave transceiver and PMX50 power management chip. So far, Qualcomm is not revealing more details of modem that will sample next year and be in production before June 2018.

Verizon and Korea Telecom will use the chips in separate trials starting late next year, anticipating commercial services in 2018. The new chips mark a departure from prototypes not intended as products that Qualcomm Research announced in June.

Korea Telecom plans a mobile 5G offering at the February 2018 Winter Olympics. Verizon plans to launch in 2018 a less ambitious fixed-wireless service in the U.S. based on a specification it released in July. KT and Verizon are among a quartet of carriers that formed a group in February to share results of early 5G trials.

For its part, the 3GPP standards group is also stepping up the pace of the 5G standards efforts it officially started earlier this year. It endorsed last month a proposal to consider moving the date for finishing Phase I, an initial version of 5G anchored to LTE, from June 2018 to as early as December 2017, according to a recent Qualcomm blog.

Coming back to Verizon's 5G standard, is it good enough and compatible with 3GPP standards? The answer right now seems to be NO.

The following is from Rethink Wireless:

The issue is that Verizon’s specs include a subcarrier spacing value of 75 kHz, whereas the 3GPP has laid out guidelines that subcarrier spacing must increase by 30 kHz at a time, according to research from Signals Research Group. This means that different networks can work in synergy if required without interfering with each other.

Verizon’s 5G specs do stick to 3GPP requirements in that it includes MIMO and millimeter wave (mmWave). MmWave is a technology that both AT&T and Verizon are leading the way in – which could succeed in establishing spectrum which is licensed fairly traditionally as the core of the US’s high frequency build outs.

A Verizon-fronted group recently rejected a proposal from AT&T to push the 3GPP into finalizing an initial 5G standard for late 2017, thus returning to the original proposed time of June 2018. Verizon was supported by Samsung, ZTE, Deutsche Telecom, France Telecom, TIM and others, which were concerned the split would defocus SA and New Radio efforts and even delay those standards being finalized.

Verizon has been openly criticized in the industry, mostly by AT&T (unsurprisingly), as its hastiness may lead to fragmentation – yet it still looks likely to beat AT&T to be the first operator to deploy 5G, if only for fixed access.

Verizon probably wants the industry to believe that it was prepared for eventualities such as this – prior to the study from Signal Research Group, the operator said its pre-standard implementation will be close enough to the standard that it could easily achieve full compatibility with simple alterations. However, Signals Research Group’s president Michael Thelander has been working with the 3GPP since the 5G standard was birthed, and he begs to differ.

Thelander told FierceWireless, “I believe what Verizon is doing is not hardware-upgradeable to the real specification. It’s great to be trialing, even if you define your own spec, just to kind of get out there and play around with things. That’s great and wonderful and hats off to them. But when you oversell it and call it 5G and talk about commercial services, it’s not 5G. It’s really its own spec that has nothing to do with Release 16, which is still three years away. Just because you have something that operates in millimeter wave spectrum and uses Massive MIMO and OFDM, that doesn’t make it a 5G solution.”

Back in the 3G days, NTT Docomo was the leader in standards and it didn't have enough patience to wait for 3GPP standards to complete. As a result it released its first 3G network called FOMA (Freedom of Mobile Access) based on pre-standard version of specs. This resulted in handset manufacturers having to tweak their software to cope with this version and it suffered from economy of scale. Early version of 3G phones were also not able to roam on the Docomo network. In a way, Verizon is going down the same path.

While there can be some good learning as a result of this pre-5G standard, it may be a good idea not to get too tied into it. A standard that is not compliant will not achieve the required economy of scale, either with handsets or with dongles and other hotspot devices.


Related posts:

• AT&T's 5G Trials
• 5G New Radio (NR), Architecture options and migration from LTE
• Some more thoughts on 5G
• 3GPP Release-14 & Release-15 update

LTE, 5G and V2X

3GPP has recently completed the Initial Cellular V2X standard. The following from the news item:

The initial Cellular Vehicle-to-Everything (V2X) standard, for inclusion in the Release 14, was completed last week - during the 3GPP RAN meeting in New Orleans. It focuses on Vehicle-to-Vehicle (V2V) communications, with further enhancements to support additional V2X operational scenarios to follow, in Release 14, targeting completion during March 2017.

The 3GPP Work Item Description can be found in RP-161894.

V2V communications are based on D2D communications defined as part of ProSe services in Release 12 and Release 13 of the specification. As part of ProSe services, a new D2D interface (designated as PC5, also known as sidelink at the physical layer) was introduced and now as part of the V2V WI it has been enhanced for vehicular use cases, specifically addressing high speed (up to 250Kph) and high density (thousands of nodes).

...

For distributed scheduling (a.k.a. Mode 4) a sensing with semi-persistent transmission based mechanism was introduced. V2V traffic from a device is mostly periodic in nature. This was utilized to sense congestion on a resource and estimate future congestion on that resource. Based on estimation resources were booked. This technique optimizes the use of the channel by enhancing resource separation between transmitters that are using overlapping resources.

The design is scalable for different bandwidths including 10 MHz bandwidth.

Based on these fundamental link and system level changes there are two high level deployment configurations currently defined, and illustrated in Figure 3.

Both configurations use a dedicated carrier for V2V communications, meaning the target band is only used for PC5 based V2V communications. Also in both cases GNSS is used for time synchronization.

In “Configuration 1” scheduling and interference management of V2V traffic is supported based on distributed algorithms (Mode 4) implemented between the vehicles. As mentioned earlier the distributed algorithm is based on sensing with semi-persistent transmission. Additionally, a new mechanism where resource allocation is dependent on geographical information is introduced. Such a mechanism counters near far effect arising due to in-band emissions.

In “Configuration 2” scheduling and interference management of V2V traffic is assisted by eNBs (a.k.a. Mode 3) via control signaling over the Uu interface. The eNodeB will assign the resources being used for V2V signaling in a dynamic manner.

5G Americas has also published a whitepaper on V2X Cellular Solutions. From the press release:

Vehicle-to-Everything (V2X) communications and solutions enable the exchange of information between vehicles and much more - people (V2P), such as bicyclists and pedestrians for alerts, vehicles (V2V) for collision avoidance, infrastructure (V2I) such as roadside devices for timing and prioritization, and the network (V2N) for real time traffic routing and other cloud travel services. The goal of V2X is to improve road safety, increase the efficiency of traffic, reduce environmental impacts and provide additional traveler information services. 5G Americas, the industry trade association and voice of 5G and LTE for the Americas, today announced the publication of a technical whitepaper titled V2X Cellular Solutions that details new connected car opportunities for the cellular and automotive industries.

The whitepaper describes the benefits that Cellular V2X (C-V2X) can provide to support the U.S. Department of Transportation objectives of improving safety and reducing vehicular crashes. Cellular V2X can also be instrumental in transforming the transportation experience by enhancing traveler and traffic information for societal goals.

C-V2X is part of the 3GPP specifications in Release 14. 3GPP announced the completion of the initial C-V2X standard in September 2016. There is a robust evolutionary roadmap for C-V2X towards 5G with a strong ecosystem in place. C-V2X will be a key technology enabler for the safer, more autonomous vehicle of the future.

The whitepaper is embedded below:

Related posts:

• Feasibility Study on New Services and Markets Technology Enablers for 5G
• Connected and Autonomous vehicles: Beyond Infotainment and Telematics
• Connected and Autonomous Car Revolution

Further Reading:

• Personal View: LTE V2X Specifications approved by 3GPP RAN plenary – Eiko Seidel

5G New Radio (NR), Architecture options and migration from LTE

You have probably read about the demanding requirements for 5G in many of my blog posts. To meet these demanding requirements a 'next-generation radio' or 'new radio' (NR) will be introduced in time for 5G. We dont know as of yet what air interface, modulation technology, number of antennas, etc. for this NR but this slide above from Qualcomm gives an idea of what technologies will be required for this 5G NR.

The slide above gives a list of design innovations that will be required across diverse services as envisioned by 5G proponents.

It should be mentioned that Rel-10/11/12 version of LTE is referred to as LTE-Advanced and Rel-13/14 is being referred to as LTE-A Pro. Rel-15 will probably have a new name but in various discussions its being referred to as eLTE.

When first phase of 5G arrives in Rel-15, eLTE would be used for access network and EPC will still be used for core network. 5G will use NR and eventually get a new core network, probably in time for phase 2. This is often referred to as next generation core network (NGCN).

The slides below from Deutsche Telekom show their vision of how operators should migrate from eLTE to 5G.

The slides below from AT&T show their vision of LTE to 5G migration.

Eiko Seidel posted the following in 3GPP 5G standards group (i recommend you join if you want to follow technical discussions)


Summary RAN1#86 on New Radio (5G) Gothenburg, Sweden

At this meeting RAN1 delegates presented and discussed numerous evaluation results mainly in the areas of waveforms and channel coding.

Nonetheless RAN1 was not yet prepared to take many technical decisions. Most agreements are still rather general. 

First NR terminology has been defined. For describing time structures mini-slots have been introduced: a mini-slot is the smallest possible scheduling unit and smaller than a slot or a subframe.

Discussions on waveforms favored filtered and windowed OFDM. Channel coding discussions were in favor of LDPC and Turbo codes. But no decisions have been made yet.

Not having taken many decisions at this meeting, RAN1 now is behind its schedule for New Radio.
Hopefully the lag can be made up at two additional NR specific ad hoc meetings that have been scheduled for January and June 2017.

(thanks to my colleague and friend Dr. Frank Kowalewski for writing this short summary!)

Yet another post from Eiko on 3GPP RAN 3 on related topic.

The RAN3 schedule is that in February 2017 recommendations can be made for a protocol architecture.  In the meeting arguments came up by some parties that the work plan is mainly addressing U-Plane architecture and that split of C- and U-plane is not considered sufficiently. The background is that the first step will be dual connectivity with LTE using LTE RRC as control plane and some companies would like to concentrate on this initially. It looks like that a prioritization of features might happen in November timeframe. Beside UP and CP split, also the functional split between the central RAN node and the distributed RAN node is taking place for the cloud RAN fronthaul interface. Besides this, also discussion on the fronthaul interface takes place and it will be interesting to see if RAN3 will take the initiative to standardize a CPRI like interface for 5G. Basically on each of the three interfaces controversial discussion is ongoing.

Yet another basic question is, what is actually considered as a “New 5G RAN”? Is this term limited to a 5G eNB connected to the NG core? Or can it also be also an eLTE eNB with Dual Connectivity to 5G? Must this eLTE eNB be connected to the 5G core or is it already a 5G RAN when connected to the EPC? 

Finally, a slide from Qualcomm on 5G NR standardization & launch.

5G Fronthaul: Crosshaul & XHaul

I have written about Fronthaul as part of C-RAN in this blog as well as in the Small Cells blog. I am also critical of the C-RAN concept now that the Baseband Units (BBU) have become small enough to go on the cell cite. I have expressed this view openly as can be seen in my tweet below.

Someone finally said it - "Fronthaul is a manmade problem." #CRAN #5G https://t.co/B1uuJqLiQy

— Zahid Ghadialy (@zahidtg) September 1, 2016

While I am critical of the C-RAN approach, there are many vendors and engineers & architects within these vendors who are for or against this technology. I am going to leave the benefits and drawbacks of C-RAN in light of new developments (think Moore's law) for some other day.

The above picture from my earlier post explains the concept of Fronthaul and Backhaul for anyone who may not be aware. As data speeds keep on increasing with 4G, 4.5G, 4.9G, 5G, etc. it makes much more sense to use Fiber for Fronthaul. Dark fiber would be a far better choice than a lit one.

One thing that concerned me was what happens in case of MIMO or massive MIMO in 5G. Would we need multiple Fronthaul/Fibre or just a single one would do. After having some discussions with industry colleagues, looks like a single fiber is enough.

This picture above from an NTT presentation illustrates how WDM (Wavelength Division Multiplexing) can be used to send different light wavelengths over a single fiber thereby avoiding the need to have multiple of these fibers in the fronthaul.

There are 2 different projects ongoing to define 5G Fronthaul & Backhaul.

The first of these is 5G Crosshaul. Their website says:

The 5G-Crosshaul project aims at developing a 5G integrated backhaul and fronthaul transport network enabling a flexible and software-defined reconfiguration of all networking elements in a multi-tenant and service-oriented unified management environment. The 5G-Crosshaul transport network envisioned will consist of high-capacity switches and heterogeneous transmission links (e.g., fibre or wireless optics, high-capacity copper, mmWave) interconnecting Remote Radio Heads, 5GPoAs (e.g., macro and small cells), cloud-processing units (mini data centres), and points-of-presence of the core networks of one or multiple service providers. This transport network will flexibly interconnect distributed 5G radio access and core network functions, hosted on in-network cloud nodes, through the implementation of: (i) a control infrastructure using a unified, abstract network model for control plane integration (Crosshaul Control Infrastructure, XCI); (ii) a unified data plane encompassing innovative high-capacity transmission technologies and novel deterministic-latency switch architectures (Crosshaul Packet Forwarding Element, XFE).

The second is 5G XHaul. Their website says:

5G-XHaul proposes a converged optical and wireless network solution able to flexibly connect Small Cells to the core network. Exploiting user mobility, our solution allows the dynamic allocation of network resources to predicted and actual hotspots. To support these novel concepts, we will develop:

• Dynamically programmable, high capacity, low latency, point-to-multipoint mm-Wave transceivers, cooperating with Sub-6 GHz systems;
• A Time Shared Optical Network offering elastic and fine granular bandwidth allocation, cooperating with advanced passive optical networks;
• A software-defined cognitive control plane, able to forecast traffic demand in time and space, and the ability to reconfigure network components.

The well balanced 5G-XHaul consortium of industrial and research partners with unique expertise and skills across the constituent domains of communication systems and networks will create impact through:

• Developing novel converged optical/wireless architectures and network management algorithms for mobile scenarios;
• Introduce advanced mm-Wave and optical transceivers and control functions;
• Support the development of international standards through technical and technoeconomic contributions.

The differences are summarised in the document below:

5G Crosshaul vs 5G-XHaul from 3G4G

It remains to be seen if C-RAN will play a big role in 5G. If yes how much of Crosshaul and XHaul will help.

Further reading:

• Fronthaul and backhaul: Look out, a fusion is coming! - Alan Carlton, Interdigital
• RAN Evolution Project: Backhaul and Fronthaul Evolution - NGMN
• Examining the fronthaul opportunities for future radio access - Shigeru Kuwano, NTT Access Network Service Systems
• 5 Things You Need to Know About vRAN: “vRAN architecture: centralize or distribute” - Amir Atai, Parallel Wireless
• 5G-XHaul project looks at WDM-PON for mobile fronthaul, backhaul - Lightwave
• Why WDM is essential in C-RAN fronthaul networks? - Ultra high CPRI link capacity - Steve Shin and Dr. Harrison J. Son, Netmanias
• Fronthaul Evolution Toward 5G: Standards and Proof of Concepts