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.
