The 3G4G Blog

Saturday 31 December 2016

Saturday 10 December 2016

Free Apps for Field Testing

People who follow me on Twitter may have often noticed I put photos when I am doing surveys, field testing, debugging, etc. In the good old days we often had to carry a lot of different kind of specialised test equipment to do basic measurements. Nowadays a lot of these can be done with the help of free apps on Android phones. The best tool that can provide a great amount of info is Qualcomm's QXDM but its really expensive.

Here are a few tools that I use. If you have one that I havent listed below, please add it in comments.

The screen shot shows the main tools along with my favourite, SpeedTest. While I agree that Speedtest is not the most reliable approach to speed of your connection, I think its the most standard one being used.

WiFi Analyzer is another great app that can be used at home and other locations where people complain about not getting good WiFi speeds. I have been at locations where the 2.4GHz is absolutely packed with APs. 5GHz is also getting busier, though there are still a lot of free channels.

G-NetTrack Lite is a great tool to keep track of the cells you have been visiting. In case you are driving this can collect a lot of valuable info. The paid version, G-NetTrack Pro can collect the info in form of a map that can be used for offline viewing with the help of Google Earth.

I use LTE Discovery mainly for finding the band I am currently camped on. It would be great if a tool can give the exact frequency and earfcn but the band is good enough too. I was once in a situation where I could see two different cells but they had the same PCI. Only after using this, I figured out they were on different bands.

Finally, Network Cell Info Lite gives neighbour cells which can often be useful. I am not sure of these are the neighbours from System Info or from Measurement Control messages sent by network or just something like Detected cells that the phone sees around.

Pind and IPConfig are other tools that can come handy sometimes.

Are there any other tools that you like? Please share using comments.

Free Apps for Field Testing - Part 2

Sunday 4 December 2016

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:

Wednesday 23 November 2016

Facebook's Attempt to Connect the Unconnected

I am sure that by now everyone is aware of Facebook's attempt to connect the people in rural and remote areas. Back in March they published the State of Connectivity report highlighting that there are still over 4 billion people that are unconnected.

The chart above is very interesting and shows that there are still people who use 2G to access Facebook. Personally, I am not sure if these charts take Wi-Fi into account or not.

In my earlier post in the Small Cells blog, I have made a case for using Small Cells as the best solution for rural & remote coverage. There are a variety of options for power including wind turbines, solar power and even the old fashioned diesel/petrol generators. The main challenge is sometimes the backhaul. To solve this issue Facebook has been working on its drones as a means of providing the backhaul connectivity.

Recently Facebook held its first Telco Infra Project (TIP) Summit in California. The intention was to bring the diverse set of members (over 300 as I write this post) in a room, discuss ideas and ongoing projects.

There were quite a few interesting talks (videos available here). I have embedded the slides and the talk by SK Telecom below but before I that I was to highlight the important point made by AMN.

As can be seen in the picture above, technology is just one of the challenges in providing rural and remote connectivity. There are other challenges that have to be considered too.

Embedded below is the talk provided by Dr. Alex Jinsung Choi, CTO, SK Telecom and TIP Chairman and the slides follow that.

View more on edocr

For more info, see:

Download the TIP slides from here.

Thursday 17 November 2016

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.

Saturday 12 November 2016

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:

Sunday 6 November 2016

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:

Saturday 29 October 2016

M2M vs IoT

This post is for mainly for my engineering colleagues. Over the years I have had many discussions to explain the difference between Machine-to-Machine (M2M) or Machine Type Communication (MTC) as 3GPP refers to them and the Internet of Things (IoT). Even after explaining the differences, I am often told that this is not correct. Hence I am putting this out here. Please feel free to express your views in the comments section.

Lets take an example of an office with 3 floors. Lets assume that each floor has a coffee machine like the one in this picture or something similar. Lets assume different scenarios:

Scenario 1: No connectivity
In this case a facilities person has to manually go to each of the floor and check if there are enough coffee beans, chocolate powder, milk powder, etc. He/She may have to do this say 3-4 times a day.

Scenario 2: Basic connectivity (M2M)
Lets say the coffee machine has basic sensors so it can send some kind of notification (on your phone or email or message, etc.) whenever the coffee beans, chocolate powder, milk powder, etc., falls below a certain level. In some cases you may also be able to check the levels using some kind of a app on your phone or computer. This is an example of M2M

Scenario 3: Advanced connectivity (IoT)
Lets say that the coffee machine is connected to the office system and database. It knows which employees come when and what is their coffee/drinks consumption pattern. This way the machine can optimize when it needs to be topped up. If there is a large meeting/event going on, the coffee machine can even check before the breaks and indicate in advance that it needs topping up with beans/chocolate/milk/etc.

Scenario 4: Intelligent Devices (Advanced IoT)
If we take the coffee machine from scenario 3 and add intelligence to it, it can even know about the inventory. How much of coffee beans, chocolate powder, milk powder, etc is in stock and when would they need ordering again. It can have an employee UI (User Interface) that can be used by employees to give feedback on which coffee beans are more/less popular or what drinks are popular. This info can be used by the machines to order the supplies, taking into account the price, availability, etc.

In many cases, API's would be available for people to build services on top of the basic available services to make life easier. Someone for example can build a service that if a cup is already at the dispenser and has been there for at least 2 minutes (so you know its not being used by someone else) then the person can choose/order their favourite drink from their seat so he/she doesn't have to wait for 30 seconds at the machine.

If you think about this further you will notice that in this scenario the only requirement for the human is to clean the coffee machine, top it up, etc. In future these can be automated with robots carrying out these kinds of jobs. There would be no need for humans to do these menial tasks.

I really like this slide from InterDigital as it captures the difference between M2M and IoT very well, especially in the light of the discussion above.

With the current M2M, we have:

Connectivity: connection for machines;
Content: massive raw data from things;

IoT is Communication to/from things which offer new services via cloud / context / collaboration / cognition technologies.

With evolution to IoT, we have:

Cloud: cloud service and XaaS (Everything as a Service) for IoT;
Context: context-aware design;
Collaboration: collaborative services;
Cognition: semantics and autonomous system adjustment

Let me know if you agree.

Sunday 23 October 2016

VoLTE Operator Case Study from LTE Voice Summit

Phil Sheppard, Director of Network Strategy & Architecture, Three UK was the keynote speaker of LTE Voice Summit held in London this month. Its been over a year that Three launched its VoLTE service in the 800MHz band. In fact recently, it has started showing adverts with Maisie Williams (Arya Stark from Game of Thrones) fighting black spots (not spots) with 4G Super-Voice.

As I highlighted in the LTEVoice 2015 summary where China Mobile group vice-president Mr.Liu Aili admitted "VoLTE network deployment is the one of the most difficult project ever, the implementation complexity and workload is unparalleled in history", Three UK's experience wasn't very different. Quoting from ThinkSmallCell summary of the event:

It was a huge project, the scope far exceeding original expectations and affecting almost every part of their operations. They spent 22,245 man days (excluding vendor staff time) – more than 100 man years of effort – mostly involved with running huge numbers of test cases on the network and devices.

There are some other interesting bits from the different summaries that are provided in references below but here are few things I found of interest with regards to Three UK VoLTE deployment:

170 million voice calls minutes have used VoLTE since the launch in Sept 2015
Only devices that can support VoLTE and 800MHz are allowed to camp on 800MHz band. This is to avoid disappointment with CS Fallback
There are plans to roll out VoLTE in other bands too once all niggles are ironed out in the 800MHz band.

Here is the presentation from 3 UK:

Blog posts summarizing LTEVoice 2016:

LTE Voice Summit 2016 Event Report - David Chambers, ThinkSmallCell
The Wi-Fi last operators, Alberto Diez
LTE Voice Summit 2016: Going beyond VoLTE to advance network performance
Summary of LTE Voice Summit 2016 - Tweet collection by Zahid Ghadialy

Related posts:

Sunday 16 October 2016

Inside 3GPP Release-13 - Whitepaper by 5G Americas

The following is from the 5G Americas press release:

The summary offers insight to the future of wireless broadband and how new requirements and technological goals will be achieved. The report updates Release 13 (Rel-13) features that are now completed at 3GPP and were not available at the time of the publication of a detailed 5G Americas report, Mobile Broadband Evolution Towards 5G: 3GPP Release 12 & Release 13 and Beyond in June 2015.

The 3GPP standards have many innovations remaining for LTE to create a foundation for 5G. Rel-12, which was finalized in December 2014, contains a vast array of features for both LTE and HSPA+ that bring greater efficiency for networks and devices, as well as enable new applications and services. Many of the Rel-12 features were extended into Rel-13. Rel-13, functionally frozen in December 2015 and completed in March 2016, continues to build on these technical capabilities while adding many robust new features.

Jim Seymour, Principal Engineer, Mobility CTO Group, Cisco and co-leader of the 5G Americas report explained, “3GPP Release 13 is just a peek behind the curtain for the unveiling of future innovations for LTE that will parallel the technical work at 3GPP on 5G. Both LTE and 5G will work together to form our connected future.”

The numerous features in the Rel-13 standards include the following for LTE-Advanced:

Active Antenna Systems (AAS), including beamforming, Multi-Input Multi-Output (MIMO) and Self-Organizing Network (SON) aspects
Enhanced signaling to support inter-site Coordinated Multi-Point Transmission and Reception (CoMP)
Carrier Aggregation (CA) enhancements to support up to 32 component carriers
Dual Connectivity (DC) enhancements to better support multi-vendor deployments with improved traffic steering
Improvements in Radio Access Network (RAN) sharing
Enhancements to Machine Type Communication (MTC)
Enhanced Proximity Services (ProSe)

Some of the standards work in Rel-13 related to spectrum efficiency include:

Licensed Assisted Access for LTE (LAA) in which LTE can be deployed in unlicensed spectrum
LTE Wireless Local Area Network (WLAN) Aggregation (LWA) where Wi-Fi can now be supported by a radio bearer and aggregated with an LTE radio bearer
Narrowband IoT (NB-IoT) where lower power wider coverage LTE carriers have been designed to support IoT applications
Downlink (DL) Multi-User Superposition Transmission (MUST) which is a new concept for transmitting more than one data layer to multiple users without time, frequency or spatial separation

“The vision for 5G is being clarified in each step of the 3GPP standards. To understand those steps, 5G Americas provides reports on the developments in this succinct, understandable format,” said Vicki Livingston, Head of Communications for the association.

The whitepaper as follows:

Whats up with VoLTE Roaming?

I have been covering the LTE Voice Summit for last couple of years (see here: 2015 & 2014) but this year I wont be around unfortunately. Anyway, I am sure there will be many interesting discussions. From my point of view, the 2 topics that have been widely discussed is roaming and VoWiFi.

One of the criticisms of VoWiFi is that it does not the QoS aspect is missing, which makes VoLTE special. In a recent post, I looked at the QoS in VoWiFi issue. If you haven't seen it, see here.

Coming back to VoLTE roaming, I came across this recent presentation by Orange.

This suggests that S8HR is a bad idea, the focus should be on LBO. For anyone who is not aware of the details of S8HR & LBO, please see my earlier blog post here. What this presentation suggests is to use LBO with no MTR (Mobile Termination Rates) but instead use TAP (Transferred Account Procedures). The presentation is embedded below:

Another approach that is not discussed too much but seems to be the norm at the moment is the use of IP eXchange (IPX). I also came across this other panel discussion on the topic

IPX is already in use for data roaming today and acts as a hub between different operators helping to solve inter-operability issues and mediating between roaming models. It can work out based on the calling and callee party what kind of quality and approach to use.

Here is the summary of the panel discussion:

Hopefully the LTE Voice Summit next week will provide some more insights. I look forward to hearing them.

Blog posts on related topics:

VoLTE Roaming – Let’s Take Away The Confusion - iBasis
VoLTE Roaming – Critical enabler or long term ideal? - 5G World
VoLTE Roaming Confusion and the IPX Provider Opportunity - Ovum
IPX providers must look internally for class-of-service customers - Ovum

Friday 30 September 2016

Quantum Technology and Future Telecommunications

Last year I posted an excerpt from an article in FT which implied that Quantum technology will play a big role in post-5G world. Earlier this month CW held their annual Technology & Engineering Conference (CW TEC). The topic was "The Quantum Revolution is coming". I have to admit that I knew next to nothing before the conference, however now I hope I know just enough to dabble in quantum technology related discussions.

The main question that I had before the conference was 'when will quantum technology be here?'. While there were different answers, depending on what you think Quantum is, I think the answer I feel comfortable is more like 2030 (just in time for 6G?)

There are already some great write-ups of the conference by others, please see links at the bottom of the post. Here are the presentations from the event:

How to build a universal quantum computer by John Morton, University College London
The end of cryptography as we know it by Michael Brown, Isara Corporation
The quantum challenge and opportunity by Paul Martin, Plextek
The UK Quantum Technology Programme and Funding Opportunities by Richard Murray, Innovate UK
Quantum sensing, positioning and navigation by Trevor Cross, e2v
The quantum challenge and opportunity by Zhiliang Yuan, Toshiba

Related Articles:

TelcoFuturism - the impact of Quantum Technology - Dean Bubley, Disruptive Analysis
Is Quantum Computing the future? Cambridge conference has the answers - Cambridge News
Quantum 2.0 has potential to create step change in computing and communications - Cambridge Wireless
Are you ready for the Quantum Revolution? - Mark England, Cambridge Consultants
Does cryptography offer data protection a quantum of solace? - David Reed, DataIQ
CW TEC 2016: The Quantum Revolution is coming! Quantum Communications & Computing: How will quantum technologies disrupt wireless?
CW TEC main page

Monday 26 September 2016

QoS in VoWiFi

Came across this presentation by Eir from last year's LTE Voice Summit.

VoWLAN: Call Quality from 3G4G

As the summary of the above presentation says:

Turning on WMM (or WME) at access point provides significant protection for voice traffic against competing wireless data traffic
Turning on WMM at the client makes only a small difference where there are a small number of clients on the wireless LAN. This plus the “TCP Unfairness” problem means that it can be omitted.
All Home gateways support WMM but their firmware may need to be altered to prioritise on DSCP rather than layer two

As this Wikipedia entry explains:

Wireless Multimedia Extensions (WME), also known as Wi-Fi Multimedia (WMM), is a Wi-Fi Alliance interoperability certification, based on the IEEE 802.11e standard. It provides basic Quality of service (QoS) features to IEEE 802.11 networks. WMM prioritizes traffic according to four Access Categories (AC): voice (AC_VO), video (AC_VI), best effort (AC_BE), and background (AC_BK). However, it does not provide guaranteed throughput. It is suitable for well-defined applications that require QoS, such as Voice over IP (VoIP) on Wi-Fi phones (VoWLAN).

WMM replaces the Wi-Fi DCF distributed coordination function for CSMA/CA wireless frame transmission with Enhanced Distributed Coordination Function (EDCF). EDCF, according to version 1.1 of the WMM specifications by the Wi-Fi Alliance, defines Access Categories labels AC_VO, AC_VI, AC_BE, and AC_BK for the Enhanced Distributed Channel Access (EDCA) parameters that are used by a WMM-enabled station to control how long it sets its Transmission Opportunity (TXOP), according to the information transmitted by the access point to the station. It is implemented for wireless QoS between RF media.

This blog post describes how the QoS works in case of WMM.

Finally, this slide from Cisco shows how it will all fit together.

Further reading:

Friday 23 September 2016

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.

Sunday 18 September 2016

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