The last time we discussed 5G and IMS. One of the main drivers for 5G is Machine-2-Machine (M2M) communication. But surely 5G is not the only technology which enables Internet of Things (IoT). Many operators already do support proprietary technologies such as SigFox or LoRaWAN. But there are also 3GPP standardized (Release 13) networks for IoT other than 5G. They are LTE-M and NB-IoT, and they both operate on licensed spectrum. These technologies came a bit later, however now it seems they are gaining momentum.
On GSMA pages you can now find an interactive map with the existing IoT deployments.
GSMA IoT Map
Let’s compare LTE-M and NB-IoT and take a look how they can benefit us.
I like statistics. Sometimes it can be misleading or data can be hard to interpret. But it can help us when we struggle to see the forest for the trees.
The last two years the IP-based mobile technologies were booming. If you are working with 4G networks you know it well. This year however the number of new deployments decreased significantly (Sep 2017, source GSMA).
IP Deployments Sep-17
Well, there can be many reasons for that. Rather than guessing, let’s have a fun and take a look on how popular are some telco topics on Google in the last 3 years.
Diameter protocol is a corner stone of all-IP telco networks. There are two main signalling protocols in IMS. Session Initiation Protocol (SIP) and right, the Diameter.
The main purpose of the SIP protocol is to establish a real-time multimedia session. This session goes end-to-end between the phones (or other devices) of the originator and recipient.
Internally – within the operator’s network – during the session establishment, we have to trigger many network functions. That can be because of the authentication of users, charging, allocation of resources, application of services, etc. 3GPP mandates for this purpose the Diameter protocol. The Diameter is used by both ePC and IMS for requesting/triggering additional information. These requests are sent in a form of transactions. During one IMS session setup or one IMS registration procedure we have to perform several Diameter transactions.
Diameter triggering during VoLTE session setup
VoLTE is a communication standard defined by GSMA and 3GPP organizations. They created plenty of documents, but these documents are not good when one is a beginner. Still it’s no rocket science. Perhaps it is because the documents don’t contain more good pictures explaining the basic ideas. I believe if the standards would be written as comic books, they’d have much broader audience 🙂
What is VoLTE?
- VoLTE stands for Voice over LTE. LTE is a new standard for wireless communication of high-speed data for mobile phones.
- Sometimes we can see also ViLTE, which means Video over LTE.
T-Mobile USA is on the cutting edge. It was the the first operator who came with HD Voice back in 2013. This month they announced a new upgrade of their network – to Enhanced Voice Services (EVS). From the customer perspective it means a better audio quality – even better than HD. EVS does this with a broader audio frequency range, which translates to richer, more realistic-sounding voice audio. The EVS is supported for both VoLTE and VoWifi. Additionally for the LTE technology it also brings a higher reliability in areas of weaker signal.
T-Mobile has a pending patent for their solution where their customers with EVS compatible phones will benefit even if the B-party doesn’t have an EVS-capable device. Currently the technology is available for LG G5, Samsung Galaxy S7 and S7 edge. T-Mobile plans to support four more smartphones by the end of 2016. I wonder what will be the response of Alliance for Open Media for webRTC.
In IT and particularly in Telco we are obsessed with abbreviations. My wife always loughs and tries to mimic me when she listens to my calls. Today we should be very careful as many of them start on ‘P’ – PCC, PCRF, PCEF, P-CSCF, PGW, PDN, PDG, PDB, PHB. But no worries, there will be abbreviations starting on other letters as well 🙂
In the IMS we have separated signalling and media data. However a full independence of control and user plane is not desirable. We want to control when the media starts and stops, we want to be sure about media routing, we want to ensure Quality of Service (QoS). And, of course, we want to accordingly charge the users.
In order to achieve these requirements we use two techniques in the VoLTE architecture:
- Policy and Charging Control (PCC)
- Differentiated Services (DiffServ)
Policy and Charging Control
PCC functionality comprises of Policy Control (e.g. QoS, media gating, ..) and Flow Based Charging. The ETSI TS 29.212, 29.213, 29.214 and 29.203 define Policy and Charging Control Architecture. There are many PCC functions defined. For us the main 3 PCC elements are:
- Application Function (AF)
- Policy Charging and Rules Function (PCRF)
- Policy Control Enforcement Function (PCEF)
Policy and Charging Control (PCC) Architecture
In VoLTE is the AF incorporated within the Proxy-CSCF. The P-CSCF provides the information related to the control plane signaling. The information is taken from SIP/SDP session setup and it is forwarded to the PCRF via the Rx reference point. Each new SIP message that includes an SDP payload or session events (e.g. session termination, modification) can trigger a new request sent towards the PCRF. This ensures that the PCRF gets the proper information in order to perform reliable PCC.
It’s called convergence. Two different approaches end-up with the same solution. In the nature it can be a bird and a bat (mammal). The both fly using wings although their ways to the result were quite independent.
In technology we can also use the synergism of the convergence. Simply we can reuse a technology which is already in place instead of creating a new one. A good example is the activity of NASA and Verizon to use the LTE eNodeB towers for air traffic control of drones (UAVs). Amazing – just a few years ago there was no LTE and no Drones.
Yesterday Deutsche Telecom (T-Mobile Germany) along with Inmarsat and Lufthansa announced their plans to create a new LTE network which would enable high-speed Internet for aviation passengers in Europe.
The network is called European Aviation Network (EAN). It will consist of the Inmarsat S-band satellite with multi-beam pan-European coverage and approximately 300 LTE sites. Each of the LTE sites will have a range of more than 80 km (comparing to traditional range of 10 km or less) and will be able to transmit data to the planes’ operating altitude. Moreover they should be flexible enough to deal with the speed of a plane. Lufthansa should start with a flight trial program in 2017.
Update: First trials
One wonders (with the coming IoT), how far we’re from unpiloted flights now?