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When the iPhone hit the street in July 2007 the early adopters were amazed at the short battery life, typically three to four hours. Software upgrades have improved that figure, but it is still an issue.  

 

The screen blanks out when not in use to save energy, but the device is only in a semi-idle state and it will continue to receive emails and instant messages. You’re informed because the phone bleeps or trembles, so the real energy savings are minimal at best. And if you get a stream of information throughout the day, then this “solution” actually makes thing worse because both the smartphone and the network have to handle a stream of signalling messages.

 

 

In order to understand the apparent anomaly whereby switching to a semi-idle state continues to drain the battery you have to understand the signalling process.

 

Smartphones can be forced into a semi-idle state when not sending or receiving any information, but when new information is sent a new connection has to be established. Each time there is an email or IM the network either has to find your device (if you have moved to another cell site), tell it to become active, check who you are, change your status in its database, allocate an IP address and finally set-up a dedicated connection from you all the way through the network to the Internet.

 

A regular network takes 21 signalling messages to complete this process. It only takes a split second, but it could happen every few minutes, so there is a significant impact on both battery life and network capacity. The latter can cause congestion, which results in a poorer service for all cell phone users.

 

So what can a smart network do to ameliorate this situation?

 

 

A smart network can perform the same process with just four messages and this reduced signalling load boosts battery life significantly. The precise figure will vary from one user to another, but according to Nokia Siemens (News - Alert) it can be doubled. 

 

The enabling technology is known as Paging Channel and it has been specified by 3GPP. It shuts down the device’s transmitter and receiver, putting them into a power saving state to reduce power consumption while maintaining a dedicated connection. And in addition to doubling battery life, it can reduce network signalling and congestion by five times. In addition, PCH can save the average service provider up to $60 million.

 

Nokia Siemens states that they are the only vendor that has implemented this complex technology i.e. got it to work in the field.

Moreover, it was implemented before smartphones were introduced. The reason why this vendor is ahead of the curve comes from the fact that Nokia Networks preceded Nokia Siemens Networks (News - Alert) and at that time there was a very close relationship with Nokia Phones. Therefore both parties were aware of the issues that would arise when the processing power of cell phones increased to the level at which these devices became hand-held computers.

 

Critics were quick to point out the march that Apple (News - Alert) stole over Nokia when the iPhone was introduced, but the Finnish vendor obviously knew the direction in which cell phones were heading.

 

 

More recently the performance of 3G networks – particularly those in the States – has been severely criticized. The fact that networks are becoming congested is clearly caused by the number of smartphone subscriptions and the applications they enable. 

 

Gartner estimates that sales will grow 33 percent this year and reach 43 percent of mobile devices by 2013. In addition, a wide range of always-on applications is generating a huge increase in traffic that is expected to double each year for the foreseeable future. For example, according to Informa (News - Alert), Ovi generated around 1 million downloads in a single day and Apple has registered over 3 billion downloads. And when China Mobile opened their Mobile Market in 2009, there were 200 downloads in the first three weeks.

 

To get an impression of the impact on the network load: viewing a YouTube video on a smartphone uses as much network capacity as sending 500,000 text messages simultaneously.

 

 

AT&T’s network has received the most criticism and they have acknowledged that its US wireless service needs an upgrade. At the end of January the company announced that it is allocating an additional $2 billion or so on this upgrade, i.e. as one critic observed, “The company is putting its money where its apologetic mouth is.”  

 

Carriers clearly need to increase capacity in order to keep pace with market requirements, but Nokia Siemens are indicating that significant improvements can be made without breaking the bank. Paging Channel technology helps reduce congestion by minimizing the number of signalling messages. Another technology known as load sharing makes optimum use of existing resources.  

 

Mobility itself makes predicting traffic across a network tough. During rush hour, around the world, millions of people change their location, all at the same time, putting varying loads on changing locations across mobile networks at different times of the day. So how does a mobile operator cope with the fact that this expensive capacity is being wasted? 

 

For example, business districts will be geared to support peaks in traffic at certain times in the week, but empty at weekends and in the evenings. And in the evenings traffic will rise in areas where people go to socialize. Moreover it will be particularly high if it’s an area favored by the younger element since they are more likely to download a video, show it to their friends who will then go on and download it themselves.   

 

The network cells in mobile telephony systems must be dimensioned for the case of heavy load, although the average load is significantly lower. Radio Network Controller load sharing, as the term implies, is a technique that allows network capacity to be shared over a wide area. Thus, capacity would be moved from the business district to the social center of the city in the evenings and weekend. 

 

Nokia Siemens states that the ability to use all the resources for all the cells is a technique that they pioneered and here too they seem to be ahead of the curve. The ability to accommodate the movement of people and the change in network traffic it causes results in a better smartphone experience as well as savings of around $15 million for the average mobile operator.