Robin Kent writes:
After initially suffering from slow pick up by consumers, 4G has begun to accelerate, and is now well on the way to the forecasted one billion subscribers by 2017. In fact EE, owner of T-Mobile and Orange, recently announced the addition of 493,000 new 4G customers to its existing base of 1.2 million.
Combine this development with the fact that smartphones recently overtook the sale of feature phones for the first time and are now seeing a fundamental shift in the way mobile services are provided. While new mobile technology presents a great deal of opportunity, unprepared network operators are also facing serious issues as the rapidly increasing number of users will put them at risk of a ‘bottleneck’ in their signaling network.
Global smartphone sales led the market for the first time in August, with Gartner reporting a 46.5 per cent increase in sales compared to a 21 per cent drop for feature phones. With 435 million mobile phones shipped in Q2 2013 in total, this represents a staggering number of new smart phones. Gartner also predicts that global tablet shipments will increase by 53.4 per cent in 2014.
Impressive though the number of devices is, it is the way they are used that will have a real impact on network signaling infrastructure. With the current generation of devices connected to 3G networks, most users will only have one or two applications running at a time. However, running on a 4G network smart devices are capable of smoothly running multiple applications at the same time.
Every time an application is used it sends a Diameter signaling request to the network and receives an acknowledgement, or ‘attach’. When a user, device or application tries to connect to the network, Diameter sends a ‘start attach’ request and the user is validated. The session is then created and a ‘complete attach’ happens so that the data is sent. Finally, when the session is complete a ‘detach’ is sent. During that session Diameter also has to track the device to manage the location and move the user between network areas, or cells.
Every Diameter transaction therefore includes a minimum of four messages, but could use many more depending on the application. Standard mobile functions like placing calls and sending text messages require a signal exchange at the start and end of the process, but newer applications such as Facebook, Twitter and online gaming require constant updates.
There are approximately 40,000-45,000 Diameter transactions per second (TPS) for every one million subscribers, with the average message size standing at 200 bytes. While it’s not a massive amount of bandwidth, it is a huge number of transactions and they all have to be executed in real time. Enough TPS can easily consume up to 80 per cent of even the most powerful central processing unit on the host’
Networks experiencing more signaling traffic than they can handle will see major issues in the form of slowdown and timeouts – or in extreme cases may even crash entirely. With this slowdown the signaling request is severely delayed, and timeout occurs when the request fails and is resent. This can lead to an event called a retry curve, with users creating even more traffic by trying to connect again, thus adding even more strain to the network.
The second annual LTE Diameter Signaling Index published by Oracle Communications predicts that LTE Diameter signaling traffic will increase at a 140 per cent compound annual growth rate (CAGR) worldwide, expanding from 1.2 million messages per second (MPS) in 2012 to 99 million MPS in 2017. This means we’re set to go from around 300,000 TPS today to 25 million by 2017.
While today’s LTE infrastructure is able to cope with the current level of traffic, it is vital that network operators prepare themselves for this exponential surge. Diameter Routers for example are designed to offer respite to the core network during times of heavy signaling traffic by offloading the Diameter signaling from the network nodes such as the Mobility Management Entity (MME), Home Subscriber Server (HSS) and Policy and Charging Enforcement Function (PCEF).
Operators must make sure their chosen solution is flexible and can be scaled upwards as demand increases. Operators that do not equip themselves with an adaptable solution will face much larger expense in the near future when they are forced to expand again in a few years’ time, as well as risking being caught off guard by sudden surges. By keeping themselves ahead of the curve and making the investment a matter of CAPEX rather than OPEX, operators can ensure a smooth and consistent level of service and keep customer satisfaction high.
Customer expectations are also changing quickly, making a reliable and consistence service even more important. 3G users are used to long waits and timeouts for activities like video streaming and internet browsing, but 4G is being heavily promoted around its high level of speed and reliability and customers will be much less tolerant of delay.
The new market is dominated by media and video content as illustrated by the current Vodafone, Sky and BT campaigns offering exclusive content deals. This will increase both the demand for a reliable service, and the level of traffic generated. Network operators that are unprepared for this new surge are at risk of everything from unhappy customers to total service crashes, while those that have equipped themselves to handle it are set to benefit from a lucrative and fast growing new market.
|Robin Kent is director of European operations at Adax, which describes itself as an industry leader in high-performance packet processing, security, and network infrastructure for the All-IP network.