Showing posts with label Network Architecture. Show all posts
Showing posts with label Network Architecture. Show all posts

Sunday 30 June 2013

Multi-RAT mobile backhaul for Het-Nets

Recently got another opportunity to hear from Andy Sutton, Principal Network Architect, Network Strategy, EE. His earlier presentation from our Cambridge Wireless event is here. There were many interesting bits in this presentation and some of the ones I found interesting is as follows:

Interesting to see in the above that the LTE traffic in the backhaul is separated by the QCI (QoS Class Identifiers - see here) as opposed to the 2G/3G traffic.




This is EE's implementation. As you may notice 2G and 4G use SRAN (Single RAN) while 3G is separate. As I mentioned a few times, I think 3G networks will probably be switched off before the 2G networks, mainly because there are a lot more 2G M2M devices that requires little data to be sent and not consume lots of energy (which is an issue in 3G), so this architecture may be suited well.


Finally, a practical network implementation which looks different from the text book picture and the often touted 'flat' architecture. Andy did mention that they see a ping latency of 30-50ms in the LTE network as opposed to around 100ms in the UMTS networks.


Mark Gilmour was able to prove this point practically.

Here is the complete presentation:



Tuesday 28 May 2013

NEC on 'Radio Access Network' (RAN) Sharing

Its been a while we looked at anything to do with Network Sharing. The last post with an embed from Dr. Kim Larsen presentation, has already crossed 11K+ views on slideshare. Over the last few years there has been a raft of announcements about various operators sharing their networks locally with the rivals to reduce their CAPEX as well as their OPEX. Even though I understand the reasons behind the network sharing I believe that the end consumers end up losing as they may not have a means of differentiating between the different operators on a macro cell.

Certain operators on the other hand offer differentiators like residential femtocells that can enhance indoor coverage or a tie up with WiFi hotspot providers which may provide them wi-fi access on the move. The following whitepaper from NEC is an interesting read to understanding how RAN sharing in the LTE would work.



Saturday 23 March 2013

LTE for Public Safety Networks

The last presentation on this topic couple of months back has reached nearly 7K views so here is another one from a recent article on the same topic from IEEE Communications Magazine



Thursday 14 March 2013

What is WebRTC and where does it fit with LTE and IMS

This simple video from MWC should give an idea on what WebRTC is and can do:


So what exactly WebRTC is in technical terms. Here is a recent presentation from WebRTC Conference and Expo



And here is another presentation that explains where it fits in with the LTE Architecture.



Dean Bubley from Disruptive Analysis has writted extensively on this topic and his recent post "Is the telephony "threat" from VoIP & WebRTC about competition or contextualisation?" is an interesting read.

Iain Sharp from Netovate recently pointed out that 3GPP have 'nearly' approved a work item for WebRTC access to IMS.

It would be interesting to see how operators will view WebRTC. As an opportunity or as a threat. Please feel free to air your opinions via comments.

Wednesday 27 February 2013

Wi-Fi & Packet Core (EPC) Integration

Yesterday I wrote a blog post on whether Wi-Fi is the third RAN in the Metrocells blog. Today I am posting this excellent presentation that details how this Wi-Fi integration with EPC will be done.



Monday 15 October 2012

Machine Type Communications (MTC): Architecture, Features, Standards in 3GPP Rel-10



The following 14 MTC Features have been identified during the 3GPP Release-10 timelines:


  • Low Mobility
  • Time Controlled
  • Time Tolerant
  • Packet Switched (PS) Only
  • Small Data Transmissions
  • Mobile Originated Only
  • Infrequent Mobile Terminated
  • MTC Monitoring
  • Priority Alarm Message (PAM)
  • Secure Connection
  • Location Specific Trigger
  • Network Provided Destination for Uplink Data
  • Infrequent Transmission
  • Group Based MTC Features




In Rel 10, 3GPP will focus on the general functionality required to support these features:

  • Overload control (Radio Network Congestion use case, Signalling Network Congestion use case and Core Network Congestion use case)
  • Addressing
  • Identifiers
  • Subscription control
  • Security



The following specifications are associated with the MTC work

Spec   - Specifications associated with or affected by MTC work
22.011 - Service accessibility
22.368 - Service requirements for Machine-Type Communications (MTC); Stage 1
23.008 - Organization of subscriber data
23.012 - Location management procedures
23.060 - General Packet Radio Service (GPRS); Service description; Stage 2
23.122 - Non-Access-Stratum (NAS) functions related to Mobile Station (MS) in idle mode
23.203 - Policy and charging control architecture
23.401 - General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access
23.402 - Architecture enhancements for non-3GPP accesses
23.888 - System improvements for Machine-Type Communications (MTC)
24.008 - Mobile radio interface Layer 3 specification; Core network protocols; Stage 3
24.301 - Non-Access-Stratum (NAS) protocol for Evolved Packet System (EPS); Stage 3
24.368 - Non-Access Stratum (NAS) configuration Management Object (MO)
25.331 - Radio Resource Control (RRC); Protocol specification
29.002 - Mobile Application Part (MAP) specification
29.018 - General Packet Radio Service (GPRS); Serving GPRS Support Node (SGSN) - Visitors Location Register (VLR); Gs interface layer 3 specification
29.060 - General Packet Radio Service (GPRS); GPRS Tunnelling Protocol (GTP) across the Gn and Gp interface
29.118 - Mobility Management Entity (MME) - Visitor Location Register (VLR) SGs interface specification
29.274 - 3GPP Evolved Packet System (EPS); Evolved General Packet Radio Service (GPRS) Tunnelling Protocol for Control plane (GTPv2-C); Stage 3
29.275 - Proxy Mobile IPv6 (PMIPv6) based Mobility and Tunnelling protocols; Stage 3
29.282 - Mobile IPv6 vendor specific option format and usage within 3GPP
31.102 - Characteristics of the Universal Subscriber Identity Module (USIM) application
33.868 - Security aspects of Machine-Type Communications
36.331 - Evolved Universal Terrestrial Radio Access (E-UTRA); Radio Resource Control (RRC); Protocol specification
37.868 - RAN Improvements for Machine-type Communications
43.868 - GERAN Improvements for Machine-type Communications
44.018 - Mobile radio interface layer 3 specification; Radio Resource Control (RRC) protocol
44.060 - General Packet Radio Service (GPRS); Mobile Station (MS) - Base Station System (BSS) interface; Radio Link Control / Medium Access Control (RLC/MAC) protocol
45.002 - Multiplexing and multiple access on the radio path


Here are couple of presentations I have extracted the above information from:



Sunday 8 July 2012

3GPP based 'Sponsored Data Connectivity'


One of the features being investigated and added is the Sponsored Data Connectivity feature in the Evolved Packet System. This feature has lots of backers as this is deemed to be a new source of revenue for the operators.

In Release-10 one of the items for this is titled 'Policy Enhancements for Sponsored Connectivity and Coherent Access to Policy related Databases (PEST)'

The justification for PEST is as follows:


With the emerging of innovative IP services, the transactional data usage is becoming more and more prevalent on the mobile. For example, the user downloads a purchased ebook from an online store; the user purchases and downloads a game from an operator store; the user views free trailer clip from an online library to determine whether to buy the entire movie or not. In many cases, the Sponsor (e.g., Application service provider) pays for the user’s data usage in order to allow the user to access the Application Service Provider’s services. This enables additional revenue opportunities for both the Application service providers and the operators.


In particular, such dynamic data usage provided by the Sponsor allows the operator to increase revenues from the users with limited data plans. The user may have limited data plans allowing only a nominal data volume per month and the Sponsor may dynamically sponsor additional volume for the user to allow access to the services offered by the Application service providers.


The PCC framework can be enhanced to enable such use cases, in particular, it allows the operator to provide service control based on such sponsored services. For example, it allows a dynamic IP flow to be excluded from the user’s data plan since a Sponsor might sponsor the data usage for the identified IP flows. For example, the user may use the limited data plan to browse an online store for interested books; but once a book is purchased, the data usage for downloading the book can be granted for free. In addition, the IP flow may also be granted certain level of QoS (e.g. video streaming).



TR 23.813 studied the feasibility of these scenarios of sponsored connectivity in the key issue 1 and converged into a set of extensions to the PCC procedures which will allow the operator to provide sponsored connectivity to sponsor entities.


In addition to Key Issue 1, SA2 also studied the feasibility of Key issue 2 - Coherent access to Policy related databases within TR 23.813. It enables UDR (User Data Repository) in the PCC architecture as an optional functional entity where PCC related subscriber data can be stored and retrieved by the PCRF through the Ud interface. This deployment scenario does not require SPR and allows the PCRF access to the PCC related subscriber data stored in the UDR.

In Release-12 PEST is linked to another new feature titled, 'Interworking between Mobile Operators using the Evolved Packet System and Data Application Providers (MOSAP)'

The Justification of this is as follows:


Mobile operators have to deal with increasing flexibility of data services delivery on different devices. 


The data services could be hosted by the mobile operators in their data centers within 3GPP domain or could be hosted by 3rd party data application providers that could be outside of the mobile operator domain. 


Current practices involve individual mobile operators negotiating agreements with data application providers resulting in proprietary additional functionalities in 3GPP networks which results in  non-standard 3GPP interfaces. With the advent of new models of services delivery like cloud computing and Application Stores, it is important that the mobile operator minimises upgrades to the network  and associated backend integration. 


Also the mobile operator has the opportunity to explore various charging models in this interworking scenario with data service providers. 


Sample services/capabilities that mobile operators can provide to data application providers are customised billing/charging, promotional services, group addressing capabilities, identity services, statistics, etc.


This WI proposes to enable the mobile operator to use enhanced functionalities and interfaces to meet the needs of the rapidly changing industry models. The WI is expected to develop requirements and architectural frameworks for authentication, authorization, policy, charging, mobility and session continuity aspects for various interworking scenarios.


The existing schemes for authentication/authorization and charging need to be studied and updated/enhanced, when deemed necessary, by liaising with other 3GPP Working Groups/SDOs/fora in charge of them.


This WI was de-prioritised in Rel-11. The Rel-12 work will take into consideration the new TS 23.682 developed in Rel-11 (Architecture Enhancements to facilitate communications with Packet Data Networks and Applications).

What are you your thoughts on sponsored data connectivity?

xoxoxoxoxoxo  Added on 08/07/2012 - 14.00 xoxoxoxoxoxo



I had a quick discussion with Dean Bubley on twitter and here is what he thinks:

Key question is what use cases & how the biz model / sponsor interaction works. 1-800 model is a #UselessCase for example. I think tollfree/1-800 apps is a nice idea, but totally unworkable when you drill into the practicalities. There are a few corner-cases & niche exceptions (eg govt-supplied apps) but proposed case for general apps / content is a chimera. 

More details on what Dean Bubley means is on his blog post here.

The comment at the end is very interesting, summarising the hurdles that exist in providing 'Toll-free data'.

My belief is that since the operators are running out of the options in generating new revenues, they may make a compromise and find a middle ground for making the 'Sponsored-data' to work

Monday 11 June 2012

The 'Virtual' Femtocell and a competition for OTT Apps

Over the last few months we have been thinking of so many ideas around small cells and this is something that we thought. It looks very simple and straightforward and having talked to a few small cells experts, off the record, none of them seem to be able to see anything wrong with this concept. With the 'Small Cells World Summit' just round the corner I am sure this could be something worth a discussion.

I am explaining the concept using an HSPA+ setup but there is no reason why this would not work in an LTE Setup. This is a typical connection for HSPA+ Femtocell setup with the gateway acting as a concentrator for all Iuh connections and having a single Iu connection towards the core. I have not shown CS/PS connection separately for simplicity. 
We propose a 'Virtual' or 'Invisible' Femtocell concept where we think that the Femtocell is redundant but the concept can be used to avoid the coverage and capacity problems faced by the operators and at the same time avoid the 'Signalling storm', atleast on the access network side. Now most smartphones have WiFi stack inbuilt. For this concept to work, WiFi in the phone is a must. Instead of having a Femtocell in between, a modified stack could be embedded in the phone itself. The output of the phone over WiFi are the Iuh messages that can terminate at the gateway and no difference would be needed from the core network side. This is illustrated in the picture below.
The phones would also need to have an enhanced UI to be able to allow a user to select only this option when roaming. You don't want a situation where the user thinks that he is camped on the 'Virtual' femtocell and making/receiving calls while he is not and run up a huge bill.

Advantages of this approach:

  • The Femtocells are no longer really needed and the end customer does not require to buy a separate equipment, which is different for different operators.
  • The phones can be working whenever a reliable WiFi connection is available, even if they are abroad without incurring costly roaming charges.
  • Some operators that do not have a lot of spectrum available avoid using Femtocells as they can cause interference and black holes in the coverage. 
  • There is no worry of a femtocell being used abroad illegally thereby causing interference with spectrum in another country.
  • Some security issues can be totally avoided and it would be worth for the operators that the keys being used cannot be seen by others.
  • A lot of people use OTT apps like Skype, Viber, Whatsapp when abroad, being camped on WiFi to avoid costly roaming charges. This approach would mean that the normal Voice and Messaging becomes similar to OTT and can help operator avoid losing out to the OTT apps. 


Disadvantages of this approach:

  • WiFi spectrum is already congested and does not always give reliable coverage.
  • Security issues would have to be looked in detail to make sure this would be secure enough. Since this concept is similar to creating a VPN between the phone and the gateway, I wouldnt think there would be any issues though.
  • Roaming revenues are a big cash cow for the operators, most of them would be unwilling to lose this if the phones are using this approach.

I think this concept is more suitable for the Residential Femtocells rather than the other Small Cells (enterprise, metro, pico, etc.) and there will always be a need for them. The main reason being that on a large scale, WiFi is extremely unreliable, prone to interference and not future proofed. A new device may cause interference that may take forever to resolve. Operating a small cell in the licensed spectrum would always make sense and the reliability would be much higher.

If you think this makes sense please click the 'Useful' checkbox so that I know.

As a company we are always looking to engage with other companies to discuss similar ideas. If you are a company dealing with Small Cells and are open to discussing similar ideas, please let us know.

Thursday 7 June 2012

On Signalling Storm... #LTEWS


The Signalling Storm is coming, its not the question of 'if' but when. This was the unanimous message from the Signaling Focus Day of the 8th LTE World Summit 2012. Several high profile outages have been associated to the Signalling storm, NTT Docomo and Verizon being the main one. Luckily the Telenor outage was due to software issues.

The problem is divided into two parts, the Access network part where the Air Interface is the bottleneck and the core network part which can easily be swamped by the overwhelming amount of Signalling due to more intelligent billing system and always on devices with background applications generating much more amount of traffic as would have on an older system. Lets look at them in turn.

Core Network Signalling Storm:

As I reported earlier, Diameter has been highlighted as a way of salvation for the operators with dozens of use cases but due to its immaturity has caused outages and have given it a bad name. As Connected Planet mentions, "According to one signaling expert, launching the iPhone’s browser, for example, instantly sets off about fifteen individual network signaling requests. Beyond that, 4G network software elements supporting increasingly sophisticated mobile service scenarios “talk” to each other at rates that traditional TDM/SS7-based networks never had to deal with." Hopefully a stable implementation of Diameter protocol will help not only solve the signalling storm but will help generate new models for charging and revenue generation.

A presentation by Ed Gubbins of Current Analysis, comparing the big vendors of Diameter Signalling is available here.

Access Network Signalling Storm:

My thinking is that the Core Network Signalling problem will become an issue some years down the road whereas the Access Network Signalling problem will be seen sooner rather than later. In fact for 3G/HSPA the problem is becoming more visible as the market has matured and more and more users are moving towards using smartphones, Since LTE rollouts are in its infancy (in most markets) the problem is still some way away.

One of the reasons for Signalling storm is the incorrect APN name. I reported earlier about Telefonica's approach to solve this problem by using 'Parking APN', see here.

Also embedded below are couple of presentations from the Signalling Focus day that talk about the problem from Access Network point of view



Other Interesting Reading Material

Finally there is an excellent whitepaper from Heavy Reading titled "The Evolution of the Signalling Challenge in 3G & 4G networks", available here to download.

Another excellent article summarising the problem is from Huawei magazine available here.

Friday 1 June 2012

On LTE Roaming ...

The IP eXchange (IPX) is used for data when the users roam between different networks. GPRS Roaming eXchange (GRX) is a service within IPX. One of the main areas of discussion within the LTE World Summit 2012 in the Signalling Focus day was roaming on LTE. Different vendors have different proposals and solutions; couple of them are as follows:



Interesting to see that iBasis has proposed LTE Signalling eXchange (LSX) as a way forward.

A presentation from Acme Packet (for an earlier conference) has interesting VoLTE roaming options proposal.

Finally, while everyone was focussing on LTE-LTE roaming, only Diametriq was looking at LTE-LTE/3G/2G Roaming. The relevant part of their presentation is embedded below.
Happy to hear more on this topic if anyone else wants to contribute. Please feel free to add comments.

Friday 11 May 2012

Updated LTE Architecture with LCS and MBMS entities

Here is an attempt to update the LTE Architecture with MBMS and Location Services (LCS) entities included



You can also refer to the following old posts:



Monday 26 March 2012

3GPP LTE Evolved Packet System & Application to Femtos

A video of the actual presentation is embedded below. Its quite long (94 minutes)



The presentation is available to download in PDF format from here.

Thursday 9 February 2012

Evolution towards ALL-IP Single RAN (SRAN)




Presented by Matthias Sauder and Dr. Volker Sebastian, VodafoneD2 GmbH in the 2nd FOKUS FUSECO Forum 2011, Berlin 17-18 Nov. 2011

Monday 30 January 2012

More on Policy and Charging in LTE

Continuing on the Policy and Charging in LTE from the previous post here.




Presented by Erik P. Neitzel, DMTS, Technology Development Group, U.S. Cellular in the LTE North America 2011 conference

Wednesday 25 January 2012

Introduction of HSS in the LTE

Click on the pic to enlarge

Interesting slides from E-Plus Mobilfunk GmbH & Co. KG presented in FUSECO Forum 17th-18th November 2011, Berlin.