News: Li-Fi – pushing the IoT forward

Do you switch-off  your smartphone or wifi, when you go to sleep? Many people do. I’m not going to discuss if the waves have any real effect on our health or psyche. But undoubtedly in the industry with more and more active devices we have to think about possible interference. Especially in the electromagnetic sensitive areas such as in aircrafts, hospitals or chemical plants.

Fortunately there is a new technology which doesn’t utilize the radio waves but still belongs to the same standard family 802.11 as Wi-Fi. Li-Fi is a bidirectional, high speed and fully wireless communication technology, that uses light from light-emitting diodes (LEDs) as a medium. The visible light spectrum is 10,000 times larger than the entire radio frequency spectrum. On the other hand the light waves cannot penetrate walls which makes a much shorter range. Still the direct line of sight isn’t a must. A light reflected off the walls can achieve 70 Mbit/s!

So what is the real data rate? The Estonian Velmenni startup  just announced that they are able to send data at up to 1GBps. That means 100-times faster than via Wi-Fi. As the British scientists have even reached the data rates of over 10 Gbit/s, which is more than 250 times faster than current broadband, we can expect further improvements in the future.



User Data Convergence – HSS-FE

I remember when I started with artificial neural networks. I read two books describing the mathematical models. Theoretically I had all information I needed, still I had no clue how to make a program which would do something.  It took me quite some time to understand how to implement such a thing in C. Those were the days before the Internet and Google 🙂   But even nowadays there is a long, long way from an IMS functional design to a real network deployment.

No, I’m not going to go through the virtualization and all the networking stuff. Instead we will look at one of the options for HSS implementation. Usually we understand the Home Subscriber Server (HSS) as a database which is providing a support and capabilities for User Identity Handling and User Security, Access Authorization, Mobile Management, Service Profile and Authorization. We can also use Subscriber Location Function (SLF) in order to map a particular subscriber to the right HSS or for loadsharing.

The definition above associates a big monolithic system, which often it is. However for some operators this can be impractical as they have to store a lot of information about their subscribers in several different databases, they have to introduce new provisioning procedures etc. Instead they could have just one ldap data-storage and the HSS would only work with the data from this database. And that’s exactly what is known as User Data Convergence (UDC) concept. In fact this is not limited only to the HSS, but the approach applies also to other systems as HLR, Provisioning Server, or ENUM. (Technicaly there can be also more than one LDAP database – e.g. we can have a dedicated cAAA LDAP database, etc.)

User Data Convergence - HSS-FE

User Data Convergence – HSS-FE

In this case we don’t talk about HSS, but about HSS Front End (HSS-FE) and User Data Repository (UDR). The interface between the HSS-FE and UDR is called Ud and you can find its description in the 3GPP TS29.335 and 3GPP TS23.335.

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News: Are the Codec Wars over?

If you are interested in the WebRTC technology, you probably know what pain it was to define Mandatory To Implement (MTI) codecs. But compromise is not always the best solution. So the key players decided to form an Alliance for Open Media – an open-source project that plans to develop next-generation media formats, codecs and technologies. The Alliance’s founding members are Amazon, Cisco, Google, Intel Corporation, Microsoft, Mozilla and Netflix. The Alliance wants to come with an open-source common standard for media sharing. It is nice to see Google, Microsoft and Mozilla to work together on web standards 🙂 Along with the HTML5 this can push forward the development of real-time communication apps a lot. On the other hand there are still many other players, many different interests, so let’s wait for the first real outcomes.

I admit this news slipped my attention. I noticed only that Edge does support the getUserMedia and then I got a bit lost in what is the WebRTC 1.0, what 1.1 and what is the Next Version (NV) 🙂 There are also other news, e.g. Google introduced a new open-source tool for developers which tests network conditions, and if camera and microphone work properly. If you missed these information as I did, you can find a nice summary with many other updates in the following video


Presence – from the other site

You know it. When you see a new smart phone/navigation/camera or any other gadget for the first time, it seems to be complex. It takes some time and you get used to. And then finally you get bored. It’s the same with the IMS. The VoLTE flows are not challenging for you any more. Maybe the conferencing or SRVCC – a bit. But in general there isn’t anything really complex. That’s why I like presence. There are many various flows and use-cases. (And I don’t deliver these trainings that often as VoLTE :)).

Sure, we’ve went through a couple of presence topics and flows (Is the Presence Social?, Presence – More than you wanted to know, What are you capable of?, Someone is watching). This time we can do it slightly more complex and check how it looks like from multi-site perspective.

Presence - two sites

Presence – two sites

We’ll go through the most basic flows and we’ll focus on what service is originating and what service is terminating. Each site can belong to a different operator or it can be just one network. For simplicity the DNS will assign the primary AS based on geolocation. Geo-redundancy scenarios will be described some other time.

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XCAP Protocol

The more protocols you know, the more of the IMS you are. Right, the IMS is not only about SIP, Diameter or RTP. There are many various protocols involved. This time we’ll take a look at self-provisioning and configuration of services via http, more specifically XML Configuration Access Protocol (XCAP). We have seen it already in the posts about Ut Interface and Aggregation Gateway.

XCAP protocol is a kind of RESTful protocol. If you know a bit about the RESTfull approach, then you should easily become familiar with XCAP.

However the XCAP was created separately and has its own specifics. It was designed as a dedicated protocol for telecommunication environment as a set of conventions for mapping XML documents and document components into HTTP URIs, along with operations allowing to read/write/modify/delete these documents. That means it is not a general purpose XML search protocol. Still the XCAP is meant to support the configuration needs for a multiple applications such as supplementary services, capabilities, resource lists, presence rules and others.

Let’s take as an example the management of VoLTE supplementary services. XCAP allows an user to retrieve the information about the provisioned services and manage the content.





As we want to limit the amount of the exchanged data, XCAP allows to define the scope of the document we are working with. The scope can be the whole document, or an xml element or even only an attribute.

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