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Showing posts with label LTE Technical. Show all posts
Showing posts with label LTE Technical. Show all 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:

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, 22 May 2016

QCI Enhancements For Mission Critical Communications

Its been quite a while since I posted about QCI and end-to-end bearer QoS in EPC. In LTE Release-12 some new QCI values were added to handle mission critical communications.


This picture is taken from a new blog called Public Safety LTE. I have discussed about the Default and Dedicated bearers in an earlier post here (see comments in that post too). You will notice in the picture above that new QCI values 65, 66, 69 & 70 have been added. For mission critical group communications new default bearer 69 would be used for signalling and dedicated bearer 65 will be used for data. Mission critical data would also benefit by using QCI 70.


LTE for Public Safety that was published last year provides a good insight on this topic as follows:

The EPS provides IP connectivity between a UE and a packet data network external to the PLMN. This is referred to as PDN connectivity service. An EPS bearer uniquely identifies traffic flows that receive a common QoS treatment. It is the level of granularity for bearer level QoS control in the EPC/E-UTRAN. All traffic mapped to the same EPS bearer receives the same bearer level packet forwarding treatment. Providing different bearer level packet forwarding treatment requires separate EPS bearers.

An EPS bearer is referred to as a GBR bearer, if dedicated network resources related to a Guaranteed Bit Rate (GBR) are permanently allocated once the bearer is established or modified. Otherwise, an EPS bearer is referred to as a non-GBR bearer.

Each EPS bearer is associated with a QoS profile including the following data:
• QoS Class Identifier (QCI): A scalar pointing in the P-GW and eNodeB to node-specific parameters that control the bearer level packet forwarding treatment in this node.
• Allocation and Retention Priority (ARP): Contains information about the priority level, the pre-emption capability, and the pre-emption vulnerability. The primary purpose of the ARP is to decide whether a bearer establishment or modification request can be accepted or needs to be rejected due to resource limitations.
• GBR: The bit rate that can be expected to be provided by a GBR bearer.
• Maximum Bit Rate (MBR): Limits the bit rate that can be expected to be provided by a GBR bearer.

Following QoS parameters are applied to an aggregated set of EPS bearers and are part of user’s subscription data:
• APN Aggregate Maximum Bit Rate (APN-AMBR): Limits the aggregate bit rate that can be expected to be provided across all non-GBR bearers and across all PDN connections associated with the APN.
• UE Aggregate Maximum Bit Rate (UE-AMBR): Limits the aggregate bit rate that can be expected to be provided across all non-GBR bearers of a UE. The UE routes uplink packets to the different EPS bearers based on uplink packet filters assigned to the bearers while the P-GW routes downlink packets to the different EPS bearers based on downlink packet filters assigned to the bearers in the PDN connection.

Figure 1.5 above shows the nodes where QoS parameters are enforced in the EPS system.

Related links:



Saturday, 2 January 2016

End to end and top to bottom network design…


A good way to start 2016 is by a lecture delivered by Andy Sutton, EE at the IET conference 'Towards 5G Mobile Technology – Vision to Reality'. The slides and the video are both embedded below. The video also contains Q&A at the end which people may find useful.




Videos of all other presentations from the conference are available here for anyone interested.

Wednesday, 18 November 2015

Cellular IoT (CIoT) or LoRa?

Back in September, 3GPP reached a decision to standardise NarrowBand IOT (NB-IOT). Now people familiar with the evolution of LTE-A UE categories may be a bit surprised with this. Upto Release-11, the lowest data rate device was UE Cat-1, which could do 10Mbps in DL and 5Mbps in UL. This was power hungry and not really that useful for low data rate sensor devices. Then we got Cat-0 as part of Release-12 which simplified the design and have 1Mbps in DL & UL.

Things start to become a bit complex in Release-13. The above picture from Qualcomm explains the evolution and use cases very well. However, to put more details to the above picture, here is some details from the 4G Americas whitepaper (embedded below)


In support of IoT, 3GPP has been working on all several related solutions and generating an abundance of LTE-based and GSM-based proposals. As a consequence, 3GPP has been developing three different cellular IoT standard- solutions in Release-13:
  • LTE-M, based on LTE evolution
  • EC-GSM, a narrowband solution based on GSM evolution, and
  • NB-LTE, a narrowband cellular IoT solution, also known as Clean Slate technologies
However, in October 2015, the 3GPP RAN body mutually agreed to study the combination of the two different narrowband IoT technical solutions, EC-GSM and NB-LTE, for standardization as a single NB-IoT technology until the December 2015 timeframe. This is in consideration of the need to support different operation modes and avoid divided industry support for two different technical solutions. It has been agreed that NB-IoT would support three modes of operation as follows:
  • ‘Stand-alone operation’ utilizing, for example, the spectrum currently being used by GERAN systems as a replacement of one or more GSM carriers,
  • ‘Guard band operation’ utilizing the unused resource blocks within a LTE carrier’s guard-band, and
  • ‘In-band operation’ utilizing resource blocks within a normal LTE carrier.

Following is a brief description of the various standard solutions being developed at 3GPP by October 2015:

LTE-M: 3GPP RAN is developing LTE-Machine-to-Machine (LTE-M) specifications for supporting LTE-based low cost CIoT in Rel-12 (Low-Cost MTC) with further enhancements planned for Rel-13 (LTE eMTC). LTE-M supports data rates of up to 1 Mbps with lower device cost and power consumption and enhanced coverage and capacity on the existing LTE carrier.

EC-GSM: In the 3GPP GERAN #62 study item “Cellular System Support for Ultra Low Complexity and Low Throughput Internet of Things”, narrowband (200 kHz) CIoT solutions for migration of existing GSM carriers sought to enhance coverage by 20 dB compared to legacy GPRS, and achieve a ten year battery life for devices that were also cost efficient. Performance objectives included improved indoor coverage, support for massive numbers of low-throughput devices, reduced device complexity, improved power efficiency and latency. Extended Coverage GSM (EC-GSM) was fully compliant with all five performance objectives according to the August 2015 TSG GERAN #67 meeting report. GERAN will continue with EC-GSM as a work item within GERAN with the expectation that standards will be frozen by March 2016. This solution necessarily requires a GSM network.

NB-LTE: In August 2015, work began in 3GPP RAN Rel-13 on a new narrowband radio access solution also termed as Clean Slate CIoT. The Clean Slate approach covers the Narrowband Cellular IoT (NB-CIoT), which was the only one of six proposed Clean Slate technologies compliant against a set of performance objectives (as noted previously) in the TSG GERAN #67 meeting report and will be part of Rel-13 to be frozen in March 2016. Also contending in the standards is Narrowband LTE Evolution (NB-LTE) which has the advantage of easy deployment across existing LTE networks.

Rel-12 introduces important improvements for M2M like lower device cost and longer battery life. Further improvements for M2M are envisioned in Rel-13 such as enhanced coverage, lower device cost and longer battery life. The narrowband CIoT solutions also aim to provide lower cost and device power consumption and better coverage; however, they will also have reduced data rates. NB CleanSlate CIoT is expected to support data rates of 160bps with extended coverage.

Table 7.1 provides some comparison of the three options to be standardized, as well as the 5G option, and shows when each release is expected to be finalized.

Another IoT technology that has been giving the cellular IoT industry run for money is the LoRa alliance. I blogged about LoRa in May and it has been a very popular post. A extract from a recent article from Rethink Research as follows:

In the past few weeks, the announcements have been ramping up. Semtech (the creator of the LoRa protocol itself, and the key IP owner) has been most active, announcing that The Lace Company, a wireless operator, has deployed LoRa network architecture in over a dozen Russian cities, claiming to cover 30m people over 9,000km2. Lace is currently aiming at building out Russian coverage, but will be able to communicate to other LoRa devices over the LoRa cloud, as the messages are managed on cloud servers once they have been transmitted from end-device to base unit via LoRaWAN.

“Our network allows the user to connect to an unlimited number of smart sensors,” said Igor Shirokov, CEO of Lace Ltd. “We are providing connectivity to any device that supports the open LoRaWAN standard. Any third party company can create new businesses and services in IoT and M2M market based on our network and the LoRaWAN protocol.”

Elsewhere, Saudi Arabian telco Du has launched a test LoRa network in Dubai, as part of a smart city test project. “This is a defining moment in the UAE’s smart city transformation,” said Carlos Domingo, senior executive officer at Du. “We need a new breed of sensor friendly network to establish the smart city ecosystem. Thanks to Du, this capability now exists in the UAE Today we’ve shown how our network capabilities and digital know-how can deliver the smart city ecosystem Dubai needs. We will not stop in Dubai; our deployment will continue country-wide throughout the UAE.”

But the biggest recent LoRa news is that Orange has committed itself to a national French network rollout, following an investment in key LoRa player Actility. Orange has previously trialed a LoRa network in Grenoble, and has said that it opted for LoRa over Sigfox thanks to its more open ecosystem – although it’s worth clarifying here that Semtech still gets a royalty on every LoRa chip that’s made, and will continue to do so until it chooses not to or instead donates the IP to the non-profit LoRa Alliance itself.

It would be interesting to see if this LoRa vs CIoT ends up the same way as WiMAX vs LTE or not.

Embedded below is the 4G Americas whitepaper as well as a LoRa presentation from Semtech:






Further reading:


Monday, 9 November 2015

5G and Evolution of the Inter-connected Network


While there are many parameters to consider when designing the next generation network, speed is the simplest one to understand and sell to the end user.

Last week, I did a keynote at the International Telecom Sync Forum (ITSF) 2015. As an analyst keynote, I looked at how the networks are evolving and getting more complex, full of interesting options and features available for the operator to decide which ones to select.

There wont just be multiple generations of technologies existing at the same time but there will also be small cells based networks, macro networks, drones and balloons based networks and satellite based networks.

My presentation is embedded below. For any reason, if you want to download it, please fill the form at the bottom of this page and download.



Just after my keynote, I came across this news in Guardian about 'Alphabet and Facebook develop rival secret drone plans'; its an interesting read. As you may be aware Google is actively working with Sri Lanka and Indonesia for providing seamless internet access nationally.


It was nice to hear EE provide the second keynote which focused on 5G. I especially liked this slide which summarised their key 5G research areas. Their presentation is embedded below and available to download from slideshare.




The panel discussion was interesting as well. As the conference focused on timing and synchronisation, the questions were on those topics too. I have some of them below, interested to hear your thoughts:

  • Who cares about syncing the core? - Everything has moved to packets, the only reason for sync is to coordinate access points in wireless for higher level services. We have multiple options to sync the edge, why bother to sync the core at all?
  • We need synchronisation to improve the user’s experience right? - Given the ever improving quality of the time-bases embedded within equipment, what exactly would happen to the user experience if synchronisation collapsed… or is good sync all about operators experience?
  • IoT… and the impact on synchronisation- can we afford it? - M2M divisions of network operators make a very small fraction of the operator’s revenue, is that going to change and will it allow the required investment in sync technology that it might require?

Sunday, 1 November 2015

Quick Summary of LTE Voice Summit 2015 (#LTEVoice)

Last year's summary of the LTE voice summit was very much appreciated so I have created one this year too.

The status of VoLTE can be very well summarised as can be seen in the image above.
‘VoLTE network deployment is the one of the most difficult project ever, the implementation complexity and workload is unparalleled in history’ - China Mobile group vice-president Mr.Liu Aili
Surprisingly, not many presentations were shared so I have gone back to the tweets and the pictures I took to compile this report. You may want to download the PDF from slideshare to be able to see the links. Hope you find it useful.



Related links:


Sunday, 26 July 2015

LTE vs TETRA for Critical Communications

Sometime back I was reading this interview between Martin Geddes and Peter Clemons on 'The Crisis in UK Critical Communications'. If you haven't read it, I urge you to read it here. One thing that stuck out was as follows:

LTE was not designed for critical communications.

Commercial mobile operators have moved from GSM to UMTS to WCDMA networks to reflect the strong growth in demand for mobile data services. Smartphones are now used for social media and streaming video. LTE technology fulfils a need to supply cheap mass market data communications.

So LTE is a data service at heart, and reflects the consumer and enterprise market shift from being predominantly voice-centric to data-centric. In this wireless data world you can still control quality to a degree. So with OFDM-A modulation we have reduced latency. We have improved how we allocate different resource blocks to different uses.

The marketing story is that we should be able to allocate dedicated resources to emergency services, so we can assure voice communications and group calling even when the network is stressed. Unfortunately, this is not the case. Even the 3GPP standards bodies and mobile operators have recognised that there are serious technology limitations.
This means they face a reputational risk in delivering a like-for-like mission-critical voice service.

Won’t this be fixed by updated standards?
The TETRA Critical Communications association (TCCA) began to engage with the 3GPP standards process in 2012. 3GPP then reached out to peers in the USA and elsewhere: the ESMCP project here in the UK, the US FirstNet programme, and the various European associations.

These lobbied 3GPP for capabilities specifically aimed at critical communications requirements. At the Edinburgh meeting in September 2014, 3GPP set up the SA6specification group, the first new group in a decade.

The hope is that by taking the critical communications requirement into a separate stream, it will no longer hold up the mass market release 12 LTE standard. Even with six meetings a year, this SA6 process will be a long one. By the end of the second meeting it had (as might be expected) only got as far as electing the chairman.

It will take time to scope out what can be achieved, and develop the critical communications functionality. For many players in the 3GPP process this is not a priority, since they are focusing solely on mass market commercial applications.

Similar point was made in another Critical communications blog here:

LTE has emerged as a long term possible replacement for TETRA in this age of mobile broadband and data. LTE offer unrivalled broadband capabilities for such applications as body warn video streaming, digital imaging, automatic vehicle location, computer-assisted dispatch, mobile and command centre apps, web access, enriched e-mail, mobile video surveillance apps such as facial recognition, enhanced Telemetry/remote diagnostics, GIS and many more. However, Phil Kidner, CEO of the TCCA pointed out recently that it will take many LTE releases to get us to the point where LTE can match TETRA on key features such as group working, pre-emptive services, network resilience, call set-up times and direct mode.
The result being, we are at a point where we have two technologies, one offering what end users want, and the other offering what end users need. This has altered the discussion, where now instead of looking at LTE as a replacement, we can look at LTE as a complimentary technology, used alongside TETRA to give end users the best of both worlds. Now the challenge appears to be how we can integrate TETRA and LTE to meet the needs and wants of our emergency services, and it seems that if we want to look for guidance and lessons on the possible harmony of TETRA and LTE we should look at the Middle East.
While I was researching, I came across this interesting presentation (embedded below) from the LTE World Summit 2015





The above is an interesting SWOT (Strengths, Weaknesses, Opportunities and Threats) analysis for TETRA and LTE. While I can understand that LTE is yet unproven, I agree on the lack of spectrum and appropriate bands.

I have been told in the past that its not just the technology which is an issue, TETRA has many functionalities that would need to be duplicated in LTE.



As you can see from this timeline above, while Rel-13 and Rel-14 will have some of these features, there are still other features that need to be included. Without which, safety of the critical communication workers and public could be compromised.

The complete presentation as follows. Feel free to voice your opinions via comments.


Monday, 4 May 2015

New LTE UE Categories: 11, 12, 13 and 14 in 3GPP Rel-12

While checking 3GPP TS 36.306, I noticed some new LTE categories have been defined. We now have all the way up to category 14. I also noticed that Wikipedia page has up to Category 15, not sure how/where they got it from. 


The LG Space page has some more details for anyone interested in exploring further.

A Qualcomm demo from MWC for LTE Category 11, if interested.



Finally, other related posts:


Sunday, 19 April 2015

3GPP Release-13 work started in earnest


The 3GPP news from some months back listed the main RAN features that have been approved for Release-13 and the work has already started on them. The following are the main features (links contain .zip files):

  • LTE in unlicensed spectrum (aka Licensed-Assisted Access) - RP-150055
  • Carrier Aggregation enhancements - RP-142286
  • LTE enhancements for Machine-Type Communications (MTC) - RP-141865
  • Enhancements for D2D - RP-142311
  • Study Item Elevation Beamforming / Full-Dimension MIMO - RP-141831
  • Study Item Enhanced multi-user transmission techniques - RP-142315
  • Study Item Indoor positioning - RP-141102
  • Study Item Single-cell Point-to-Multipoint (SC-PTM) - RP-142205


Another 3GPP presentation from late last year showed the system features that were being planned for Rel-13 as shown above.

I have also posted a few items earlier relating to Release13, as follows:


Ericsson has this week published a whitepaper on release 13, with a vision for 'Networked Society':
The vision of the Networked Society, where everything that benefits from being connected will be connected, places new requirements on connectivity. LTE is a key component in meeting these demands, and LTE release 13 is the next step in the LTE evolution.
Their whitepaper embedded below:



It should be pointed out that 5G work does not start until Release-15 as can be seen from my tweet

xoxoxo Added Later (26/04/2015) xoxoxo
I came across this presentation from Keysight (Agilent) where Moray Rumney has provided information in much more detail.


Sunday, 12 April 2015

LTE-Hetnet (LTE-H) a.k.a. LTE Wi-Fi Link Aggregation (LWA)


We have talked about the unlicensed LTE (LTE-U), re-branded as LTE-LAA many times on this blog and the 3G4G Small Cells blog. In fact some analysts have decided to call the current Rel-12 non-standardised Rel-12 version as LTE-U and the standardised version that would be available as part of Release-13 as LTE-LAA.

There is a lot of unease in the WiFi camp because LTE-LAA may hog the 5GHz spectrum that is available as license-exempt for use of Wi-Fi and other similar (future) technologies. Even though LAA may be more efficient as claimed by some vendors, it would reduce the usage for WiFi users in that particular spectrum.

As a result, some vendors have recently proposed LTE/WiFi Link Aggregation as a new feature in Release-13. Alcatel-Lucent, Ruckus Wireless and Qualcomm have all been promoting this. In fact Qualcomm has a pre-MWC teaser video on Youtube. The demo video is embedded as follows:



The Korean operator KT was also involved in demoing this in MWC along with Samsung and Qualcomm. They have termed this feature as LTE-Hetnet or LTE-H.

The Korean analyst firm Netmanias have more detailed technical info on this topic.

Link aggregation by LTE-H demonstrated at MWC 2015 (Source: Netmanias)

As can be seen the data is split/combined in PDCP layer. While this example above shows the practical implementation using C-RAN with Remote Radio Head (RRH) and BaseBand Unit (BBU) being used, the picture at the top shows LTE Anchor in eNodeB. There would be a need for an ideal backhaul to keep latency in the eNodeB to minimum when combining cellular and WiFi data.

Comparison of link level Carrier Aggregation technologies (Source: Netmanias)

The above table shows comparison between the 3 main techniques for increasing data rates through aggregation; CA, LTE-U/LAA and LTE-H/LWA. While CA has been part of 3GPP Release-10 and is available in more of less all new LTE devices, LTE-U and LTE-H is new and would need modifications in the network as well as in the devices. LTE-H would in the end provide similar benefits to LTE-U but is a safer option from devices and spectrum point of view and would be a more agreeable solution by everyone, including the WiFi community.

A final word; last year we wrote a whitepaper laying out our vision of what 4.5G is. I think we put it simply that in 4.5G, you can use WiFi and LTE at the same time. I think LTE-H fulfills that vision much better than other proposals.

Sunday, 8 March 2015

LTE Category-0 low power M2M devices


While we have talked about different LTE categories, especially higher speeds, we have not yet discussed Category-0 or Cat-0 for M2M.

A recent news report stated the following:

CAT-1 and CAT-0 are lower speed and power versions of the LTE standard which dramatically extend the addressable market for carriers and chip makers alike. They introduce new IoT targeted features, extend battery operation and lower the cost of adding LTE connectivity.
“While chipsets supporting these lower categories are essential for numerous applications, including wearable devices, smart home and smart metering, there has been an industry development gap that we had anticipated two years ago,” said Eran Eshed, co-founder and vice president of marketing and business development at Altair. “We’ve worked hard to address this gap by being first to market with true CAT-1 and 0 chipsets featuring a power/size/cost combination that is a massive game-changer.”
Ericsson has an interesting presentation that talks about LTE evolution for cellular IoT. While Rel-12 Cat-0 would use the normal allocated bandwidth (upto 20MHz), Rel-13 plans further enhancements to save even more power by reducing the bandwidth to 1.4Mhz. Another possible saving of power comes from the use of Half Duplex (but its optional). There is a very interesting presentation from Mstar semiconductors on half duplex that I have blogged about here. Anyway, the presentation from Ericsson is here:



When we talk about 50 billion M2M devices, a question that I regularly ask is how many of them will be using cellular and how many will use other technologies. Its good to see that my skepticism is shared by others as well, see the tweet below.

Click on the pic.twitter.com/Z7s6wqxkBM to see the actual media.

Nokia has also got an interesting whitepaper on this topic which talks about optimizing LTE and the architectural evolution that will lead cellular LTE to become a compelling technology so that it can be widely adopted. That paper is embedded as well below.



Sunday, 1 March 2015

Monday, 23 February 2015

Static/Dynamic IP Address Allocation in LTE


I recently came across a discussion on how static and dynamic IP address are allocated in LTE for a UE. Luckily, there is a recent document from Netmanias that discussed this topic. The document is embedded below.



If you enjoyed reading the document (part 1) above, then there is a part 2 here. While in part 1, we saw that IP addresses can be either dynamic or static depending on their allocators, part 2 presents a specific case of IP address allocation – allocation in geographically-separated locations within an LTE network. In case of dynamic allocation, no matter where a user accesses, a dynamically selected P-GW dynamically allocates an IP address to the user for PDN connection. In case of static allocation, however, there is always one specific P-GW and one IP address for a user - the designated P-GW allocates a static IP address for the user’s PDN connection. A case study shows an LTE network that serves two cities as an example to describe different ways and procedures of IP address allocation, and see how they are different from each other.

Wednesday, 21 January 2015

Voice over WiFi (VoWiFi) technical details

VoWiFi is certainly a hot topic, thanks to the support of VoWiFi on iPhone 6. A presentation from LTE World Summit 2014 by Taqua on this topic has already crossed 13K views. In this post I intend to look at the different approaches for VoWiFi and throw in some technical details. I am by no means an expert so please feel free to add your input in the comments.

Anybody reading this post is not aware of S2a, S2b, Samog, TWAG, ePDG, etc. and what they are, please refer to our whitepaper on cellular and wi-fi integration here (section 3).

There are two approaches to VoWiFi, native client already in your device or an App that could be either downloaded from the app store or pre-installed. The UK operator '3' has an app known as ThreeInTouch. While on WiFi, this app can make and receive calls and texts. The only problem is that it does not handover an ongoing call from WiFi to cellular and and vice versa. Here are a few slides (slides 36-38) from them from a conference last year:



The other operators have a native client that can use Wi-Fi as the access network for voice calls as well as the data when the device is connected on the WLAN.

A simple architecture can be seen from the picture above. As can be seen, the device can connect to the network via a non-3GPP trusted wireless access network via the TWAG or via a non-3GPP untrusted wireless access network via ePDG. In the latter case, an IPSec tunnel would have to be established between the device and the ePDG. The SIM credentials would be used for authentication purposes so that an intruder cannot access ePDG and the core.

Now, I dont want to talk about VoLTE bearers establishment, etc. which I have already done here earlier. In order to establish S2a (trusted) and S2b (untrusted) connection, the AAA server selects an APN among those which are subscribed to in the HLR/HSS. The PDN-GW (generally referred to as PGW) dynamically assigns an IP address out of a pool of addresses which is associated with this APN. This UE IP address is used by the VoWiFi SIP UA (User Agent) as the contact information when registering to the SIP soft switch (which would typically be the operators IMS network).

If for any reason the SIP UA in the device is not able to use the SIM for authentication (needs ISIM?) then a username/password based authentication credentials can be used (SIP digest authentication).

Typically, there would be a seperate UA for VoLTE and VoWiFi. They would both be generally registering to the same IMS APN using different credentials and contact addresses. The IMS network can deal with multiple registrations from the same subscriber but from different IP addresses (see 3GPP TS 23.237 - 'IMS Service Continuity' for details).

Because of multiple UA's, a new element needs to be introduced in order to 'fork' the downstream media streams (RTP/RTCP packets) to different IP addresses over time.

3GPP has defined the Access Transfer Gateway (ATGW) which is controlled by the Access Transfer Control Function (ATCF); the ATCF interfaces to the IMS and Service Centralization and Continuity Application Server (SCC AS). All these are not shown in the picture above but is available in 3GPP TS 23.237. The IMS networks in use today as well as the one being deployed for VoLTE does not have ATGW/ATCF. As a result vendors have to come up with clever non-standardised solutions to solve the problem.

When there is a handover between 3GPP and non-3GPP networks, the UE IP address needs to be preserved. Solutions like MIP and IPSec have been used in the past but they are not flexible. The Release-12 solution of eSAMOG (see 3GPP TS 23.402) can be used but the solution requires changes in the UE. For the time being we will see proprietary solutions only but hopefully in future there would be standardised solutions available.

3GPP TS 23.234 describes more in detail the interworking of 3GPP based system and WLAN. Interested readers can refer to that for further insight.

Wednesday, 7 January 2015

Enhancing voice services using VoLTE


VoLTE has been a very popular topic on this blog. My overview of the LTE Voice Summit missed out narrowly from the Top 10 posts of 2014 but there were other posts related to VoLTE that made it.

In this magazine article, NTT Docomo not only talks about its own architecture and transition from 3G to 4G for voice and video, it provides some detailed insights from its own experience.

There is also discussion into technical details of the feature and examples of signalling for VoLTE registration and originating/terminating calls (control, session and user plane establishment), SMS, SRVCC, Video over LTE (ViLTE) and voice to video call switching.

The paper is embedded below and available from slideshare to download.



Related links:

Thursday, 23 October 2014

Detailed whitepaper on Carrier Aggregation by 4G Americas

4G Americas has published a detailed whitepaper on Carrier Aggregation (CA). Its a very good detailed document for anyone wishing to study CA.


Two very important features that have come as part of CA enhancements were the multiple timing advance values that came as a part of Release-11 and TDD-FDD joint operation that came part of Release-12

While its good to see that up to 3 carriers CA is now possible as part of Rel-12 and as I mentioned in my last post, we need this to achieve the 'Real' 4G. We have to also remember at the same time that these CA makes the chipsets very complex and may affect the sensitivity of the RF receivers.

Anyway, here is the 4G Americas whitepaper.


LTE Carrier Aggregation Technology Development and Deployment Worldwide from Zahid Ghadialy

You can read more about the 4G Americas whitepaper in their press release here.

Thursday, 2 October 2014

Envelope Tracking for improving PA efficiency of mobile devices

I am sure many people would have heard of ET (Envelope Tracking) by now. Its a technology that can help reduce the power consumption by our mobile devices. Less power consumption means longer battery life, especially with all these new features coming in the LTE-A devices.
As the slide says, there are already 12 phones launched with this technology, the most high profile being iPhone 6/6 Plus. Here is a brilliant presentation from Nujira on this topic:



For people who are interested in testing this feature may want to check this Rohde&Schwarz presentation here.