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:
Further Reading:



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:

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:



Related posts:

Friday 7 October 2016

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:

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:




Related Articles:

Monday 26 September 2016

QoS in VoWiFi

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



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.



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:



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:



Sunday 11 September 2016

How much spectrum would 5G need?


The above picture is a summary of the spectrum that was agreed to be studied for IMT-2020 (5G). You can read more about that here. I have often seen discussions around how much spectrum would be needed by each operator in total. While its a complex question, we cannot be sure unless 5G is defined completely. There have been some discussions about the requirements which I am listing below. More informed readers please feel free to add your views as comments.


Real Wireless has done some demand analysis on how much spectrum is required for 5G. A report by them for European Commission is due to be published sometime soon. As can be seen in the slide above, one of the use cases is about multi gigabit motorway. If the operators deploy 5G the way they have deployed 4G then 56 GHz of spectrum would be required. If they move to a 100% shared approach where all operators act as MVNO and there is another entity that deploys all infrastcture, including spectrum then the spectrum requirement will go down to 14 GHz.

This is in addition to all the other spectrum for 2G, 3G & 4G that the operator already holds. I have embedded the presentation below and it can be downloaded from here:



The UK Spectrum Policy Forum (UKSPF) recently held a workshop on Frequency bands for 5G, the presentations for which are available to download on the link I provided.


Its going to be a huge challenge to estimate what applications will require how much amount of spectrum and what would be the priority as compared to other applications. mmMagic is one such group looking at spectrum requirements, use cases, new concepts, etc. They have estimated that around 3.1GHz would be required by each operator for 99% reliability. This seems more reasonable. It would be interesting to see how much would operators be willing to spend for such a quantity of spectrum.



Related posts: