IP Multimedia Subsystem (IMS) Support for Service Based Architecture (SBA)

I looked at IMS briefly in my LTE voice tutorial here. The Nokia Lectures covered IMS in-depth in part 5 of the video. I recently came across a short overview of IMS for SBA. You can see our old tutorial on Service Based Architecture (SBA) for 5G Core (5GC) here.

I came across this short video from Mpirical that nicely explains the IMS support for SBA. It's embedded below. The related posts at the bottom may also be worth checking out.

Related Posts:

• The 3G4G Blog: A quick starter on 4G voice (for beginners)
• The 3G4G Blog: Nokia Lectures in Collaboration with Bangalore University
• The 3G4G Blog - Tutorial: Service Based Architecture (SBA) for 5G Core (5GC)
• The 3G4G Blog: A look at 5G Applications, Application Functions & Application Servers
• The 3G4G Blog: EPS Fallback in 5G Standalone Deployments
• The 3G4G Blog: Voice over New Radio (VoNR) Establishment and Release between NG RAN and 5G Core
• The 3G4G Blog: Two Types of SMS in 5G
• The 3G4G Blog: 5G User Plane Redundancy
• The 3G4G Blog: Network Slicing using User Equipment Route Selection Policy (URSP) 

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:

• VoLTE Roaming with RAVEL (Roaming Architecture for Voice over IMS with Local Breakout)
• S8HR: Standardization of New VoLTE Roaming Architecture
• VoLTE Roaming: LBO, S8HR or HBO

Diameter Security is worse than SS7 Security?

Back in December last year, there was a flurry of news about SS7 security flaw that allowed hackers to snoop on an unsuspecting users calls and SMS. The blog readers will also be aware that SS7 is being replaced by the Diameter protocol. The main reason being to simplify roaming while at the same time being able to manage the signalling storm in the networks.


The bad news is that while is case of SS7, security issues are due to network implementation and configuration (above pic), the security issues in Diameter seem to be due to the protocol and architecture themselves (below pic)

Diameter is very important for LTE network architecture and will possibly continue in the future networks too. It is very important to identify all such issues and iron them before some hackers start exploiting the network vulnerabilities causing issues for everyone.

The presentation by Cédric Bonnet, Roaming Technical Domain Manager, Orange at Signalling Focus Day of LTE World Summit 2015 is embedded below:

From SS7 to Diameter Security from Zahid Ghadialy

Some important information from this post has been removed due to a valid complaint.

Diamater: Market Status, Roaming, NFV and Case Studies

Some more interesting presentations from the Signalling Focus Day of LTE World Summit. Good overview of market by Greg Collins of Exact ventures is embedded below.

Diameter Signaling Market Update from Zahid Ghadialy

A good presentation by Tieto where they presented some good case studies for Diameter Interworking. Presentation embedded below:

Diameter routing & interworking in NFV from Zahid Ghadialy

The final presentation by Diametriq is very interesting because they presented interesting way of mining the control plane. Thee case study presented was of a 'silent roamer' who is not going to spend money while roaming because he is not sure how much money is spent. This can be exploited by the operator to offer flat packages, 1 day pass, etc. to get some revenue from these roamers. Their presentation included some animations that cannot be shown while being embedded. Please download the PPT from Slideshare to view them.

Unlocking New Value in the Diameter Signaling Path from Zahid Ghadialy

LTE Roaming using IPX

A very interesting presentation from Raphaël Glatt of Bics in the Signalling Focus Day of LTE World Summit 2014. IPX is probably the most popular solution as its already being used by many operators for roaming agreements. Anyway, his presentation was the most detailed one I have come across and he was happy to share it with me for this blog. His complete presentation is embedded below:

Enabling Effective Roaming Through IPX from Zahid Ghadialy

International LTE Data and VoLTE Roaming - NTT Docomo

Quick recap of the Bearer Architecture: Remember the interface between S-GW and P-GW is known as S5/S8. S5 in case the S-GW and P-GW are part of the same network (non-roaming case) and S8 in case where P-GW belongs to another network than S-GW (roaming case). The S5/S8 interfaces are generally exactly the same. There is a possibility of different types of S5/S8 interfaces like GTP based and PMIP based but lets not discuss that here.

NTT Docomo published an excellent article in their magazine recently showing the different approaches to International Data roaming.

The different scenarios above are based on the guidelines provided in GSMA PRD IR.88. Each operator has to adopt one of the scenarios above, NTT Docomo has selected scenario 4. The Home PLMN (HPLMN) and the Visited PLMN (VPLMN) connect via IP eXchange (IPX).

As can be seen above, the MME in VPLMN communicates with HSS in HPLMN using Diameter Edge Agent (DEA).

Finally, it is well known that NTT Docomo is not launching VoLTE untill 2015. The above is their proposal on how they handle VoLTE while in Japan and when roaming.

The paper is an interesting read, embedded below:

NTT Docomo: Implementing LTE International Data Roaming from Zahid Ghadialy

Another article worth a read is the VoLTE roaming with RAVEL here.

Diameter, Signalling and LTE

Last year, I blogged about Signalling storm and Diamater here and here. Embedded below is a similar sort of presentation from the Fokus Fuseco Forum 2012.

What kind of signalling issues have to be solved by introducing LTE? from Zahid Ghadialy

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

Martin pineiro telecom-personal_focus-day--tues from ceobroadband

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.

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.

Diameter and LTE Roaming

View more presentations from Zahid Ghadialy

Happy to hear more on this topic if anyone else wants to contribute. Please feel free to add comments.

#LTEWS: Highlights and Pictures of Signalling day from 8th LTE World Summit

I got a chance to attend the 'Handling the Surge in Signalling Traffic Focus day' at the LTE World Summit. In fact I got this opportunity through Diametriq, who were the sponsors of this event and were kind enough to provide me a free pass :) As a result, they get a little plug below.

We got off to a flying start with an Introduction to the need of Signaling followed by a brilliant presentation by Martin Pineiro from Telecom Personal, Argentina.

This was the only presentation that looked at the Access Network Signalling. All other presentations focussed on Diameter signaling. Telecom Personal have 4 carriers, 1 is used for 3G and other 3 for GSM.

Above is their revenue share for different services. The data services really took off for them when they offered a flat rate if 1 peso per day for unlimited data.

Their average dongle data consumption is 2GB/month and average smartphone is 200MB/month.

They do have a simple definition of Smartphone, which is a device that produces 10+ packet connections per day. The device that is most popular in their network is Motorola and Apple devices produce highest data load but their comparison of devices from different manufacturers showed they all produced similar signalling traffic. 

One final point highlighted was that OS & Apps are not part of test and certification so we should get better understanding of that to help avoid signalling overload in future.

Ron de Lange from Tekelec was up next:

Interesting to hear that they are 40 year old company with 300+ customers in 100+ countries.

There is a shift coming in the usage plans with multi access roaming. Some sessions will go over WiFi and some over the mobile network. Plans with OTT allowance are already here and will be more common. There may be opportunity for end users to earn allowance as part of loyalty scheme. The main thing for operator to think is how to get a revenue share from advertisement.

Diameter 2.0 is coming. The signalling storms, if not handled properly can cause disruption (congestion) internationally, if the interconnect is not handled properly.

Next up was Ben Volkow, F5 Traffix:

Today we use Diameter 1.0, tomorrow it would be Diameter 2.0. Diamater 2.0 us "nervous system" approach.

Diamater is much less predictable than SS7 but this could be because of Immaturity of Diameter.

Real networks like the one above is out in the field. An example of n/w is one with 140 point to point connections.

DRA (Diameter Routing Agent) is a new topology introduced by 3GPP and DEA (Diameter Edge Agent) was introduced by GSMA.

The network does not want to spend million of dollars in one go so they start by deploying individual components first and then depending on the use cases this scales up as they add more components.

Next up was the Panel Discussion:

Key points:

• Diameter is first protocol that has dedicated vendors offering monetisation of protocol as well
• Early operators would have deployed Diameter 1.0 so they can evolve by putting DRA for one use case and so on.
• When operators want to monetise using diameter, the signalling problems may become worse
• Adding VoLTE may increase Diameter Signalling by 3 times
• What is meant by monetisation of Diamater is that in SS7, the focus was on reliability, etc. but in Diameter, the operators can leverage PCRF and as a result monetisation. A new use case can also be a OTT proxy that can leverage advertisement revenue. 
• The forecast for Diameter is couple of 100 million for this year and growing. There are many components including Router, Roaming, Charging, Security, Interconnect capability, Aggregating relationships with small carriers and OTT service providers, etc.

Next up was Marjan Mursec of Telecom Slovenia: 

Some interesting facts from them is that they have a public WLAN n/w, GSM with EDGE as fallback and have rolled out HD voice. Their Data usage surpasses voice and Voice and SMS is still growing as can be seen below.

Above shows the data usage increase after they rolled out all you can eat package. They were then forced to introduce fair usage policy.

Their upgrade paths include RAN, Core, Backhaul.

They think they have a big signalling challenge over S1-MME interface. One wrong configured user is sending 4 requests/second. 12,500 users can be enough to reach congestion (ZG: Maybe they should look at PDP Context Parking). Over the S1-U interface, Narrowband users can send 50 packets/sec. 40,000 users at 13.6kbps can saturate the network and the routers will be overloaded.

Next up was Ajay Joseph from iBasis:

Interesting to see that GRX is a service in IPX above.

I think the main point of above is that Diameter by itself is not enough and a mechanism like IPX is required for roaming scenario.

For LTE a new service called LTE Signalling exchange (LSX) can be created within IPX. iBasis has just launched Sandbox for testing Roaming, Charging, Interoperability, etc.

Will LSX bring the roaming costs down? Its operators call but it does provide a foundation and in the next 2-3 years, data roaming costs should come down dramatically.

It should be noted that GRX is an IP network without QoS. Its a service within IPX. Security is also a service within IPX and GSMA based compliance should be there for proper and secure interoperability.

Voice over IPX is not of much interest, especially because there is no return of investment and HD voice cant be send over IP.

Next up was Douglas Ranalli from NetNumber:

His slides are self explanatory

One question during Q&A was, why not put this functionality in the cloud and avoid complexity of having another physical box in the system. The answer was that CDRB is implemented to be compliant with cloud deployment but operators have not yet taken this step. The customers are deploying physical boxes but shared infrastructure would be much more efficient.

Next up was Doug Alston from Sprint:

Next up was Anjan Ghosal from Diametriq:

Everyone is talking about LTE-LTE roaming but there is a need for LTE-3G and LTE-2G so some translation may be required between Diameter and SS7.

Diametriq provides a single platform for signalling between any service (2G/3G/4G) and possibility to enhance.

Next up was another Panel Discussion:

One observation is made is that as compared to the ITM Optimisation event, where the operators were more worried about the OTT players eroding revenues, the focus here was that how Diameter can help monetise the OTT services,

Next up was Edward Gubbins from Current Analysis:

The Final presentation was from Julius Mueller from Fraunhofer FOKUS:

As usual, Dimitris Mavrakis was up to the mark and chaired the whole day very well.

To end an enjoyable day even better, iBasis invited the attendees for drinks on the Hilton Terrace, which is next to CCIB and complemented the drinks with some delicious Tapas as can be seen below :)

E&OE. In case if have misheard, misquoted, etc. please feel free to correct me via comments in this post.

For all the action from LTE World Summit for the next 2 days, please follow twitter #LTEWS.

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