Boosting network efficiency for smartphones
What are the network signaling system challenges facing operators as smartphone sales increase?
New signaling features boost network efficiency for smartphones
Increasing smartphone usage is good news from a revenue point of view, but it can also present a challenge for operators if their network signaling system has not been optimized for these devices.
Many popular smartphone applications – including push email, instant messaging, social networking and news services – are ‘chatty’ and instigate regular data connections for updates. It is not uncommon for smartphones to make many tens of such requests per hour, which could result in signaling congestion in poorly configured or dimensioned networks.
While there is a lot of attention paid to smartphone data usage – which is actually only around 200–500 MB per month for the typical smartphone user (compared with five to ten times this figure for mobile broadband-enabled laptop users) – the way the signaling system has been configured is a key factor in determining smartphone performance and user experience.
Optimizing device states
In WCDMA/HSPA networks, user devices can be assigned different ‘states’ to optimize the trade-off between always-on connectivity, data speed and battery life. There are five possible connection states:
Idle – there is no connection between the network and the smartphone, meaning a significant amount of signaling is needed to start a connection
URA_PCH – the smartphone is in ‘sleep’ mode, but the connection is maintained based on most recent UTRAN Registration Area (URA) location, which can be a single cell or an area comprising a number of cells. URA permits much faster network access than in idle mode at same power consumption, with half the number of messages – substantially reducing signaling
Cell_PCH – as URA_PCH, but the most recent location of the device is known at the cell level, rather than registration area, which means signaling is required each time the user changes cell
Cell_FACH – this state maintains data connectivity through a shared channel, which is good for ‘chatty’ applications with low data demands.
Cell_DCH – in this state, there is a dedicated HSPA channel, which provides excellent responsiveness and high throughput to ensure good user experience of more demanding applications.
The recommended ‘default’ state from a battery power-saving perspective is URA_PCH. If this state is not deployed, the most power-efficient issue state is ‘idle’, which will mean significantly more signaling load. This is because moving from the idle state to the Cell_FACH or Cell_DCH state involves re-establishing a connection each time – perhaps involving up to 30 signaling messages – which results in delays in the data channel becoming available and has a negative effect on user experience.
By enabling URA_PCH in their networks – which usually only involves software changes – operators can greatly reduce both the signaling load and the time it takes for data transfers to begin. For example, moving from URA_PCH to Cell_FACH involves only three signaling messages.
Enhanced network efficiency
Measurements made by Ericsson in live networks have shown that keeping devices in the URA_PCH state – rather than allowing them to drop back to idle mode each time a data transfer is completed – reduces the number of channel establishment requests by more than 50 percent.
Another feature that improves network efficiency is network-controlled Fast Dormancy. Rather than the device deciding by itself when to drop down to idle state – which most smartphones do today – this 3GPP-standardized feature returns control to the network. This improves overall efficiency by preventing repeated dormancy and reconnection requests.
Two enhancements to the Cell_FACH state are available to provide faster access to higher throughput for the short connections needed by chatty applications. Known a s HS_FACH and EUL_FACH, these ‘intermediary’ states allow the operator to keep more data users in the lower states, while giving them a ‘snappier’ experience of social networking and similar applications.
By optimizing their signaling system in this way, and dimensioning the signaling capacity where needed, operators can ensure they deliver the best smartphone user experience while maintaining an efficient network.
New signaling features boost network efficiency for smartphones
Increasing smartphone usage is good news from a revenue point of view, but it can also present a challenge for operators if their network signaling system has not been optimized for these devices.
Many popular smartphone applications – including push email, instant messaging, social networking and news services – are ‘chatty’ and instigate regular data connections for updates. It is not uncommon for smartphones to make many tens of such requests per hour, which could result in signaling congestion in poorly configured or dimensioned networks.
While there is a lot of attention paid to smartphone data usage – which is actually only around 200–500 MB per month for the typical smartphone user (compared with five to ten times this figure for mobile broadband-enabled laptop users) – the way the signaling system has been configured is a key factor in determining smartphone performance and user experience.
Optimizing device states
In WCDMA/HSPA networks, user devices can be assigned different ‘states’ to optimize the trade-off between always-on connectivity, data speed and battery life. There are five possible connection states:
Idle – there is no connection between the network and the smartphone, meaning a significant amount of signaling is needed to start a connection
URA_PCH – the smartphone is in ‘sleep’ mode, but the connection is maintained based on most recent UTRAN Registration Area (URA) location, which can be a single cell or an area comprising a number of cells. URA permits much faster network access than in idle mode at same power consumption, with half the number of messages – substantially reducing signaling
Cell_PCH – as URA_PCH, but the most recent location of the device is known at the cell level, rather than registration area, which means signaling is required each time the user changes cell
Cell_FACH – this state maintains data connectivity through a shared channel, which is good for ‘chatty’ applications with low data demands.
Cell_DCH – in this state, there is a dedicated HSPA channel, which provides excellent responsiveness and high throughput to ensure good user experience of more demanding applications.
The recommended ‘default’ state from a battery power-saving perspective is URA_PCH. If this state is not deployed, the most power-efficient issue state is ‘idle’, which will mean significantly more signaling load. This is because moving from the idle state to the Cell_FACH or Cell_DCH state involves re-establishing a connection each time – perhaps involving up to 30 signaling messages – which results in delays in the data channel becoming available and has a negative effect on user experience.
By enabling URA_PCH in their networks – which usually only involves software changes – operators can greatly reduce both the signaling load and the time it takes for data transfers to begin. For example, moving from URA_PCH to Cell_FACH involves only three signaling messages.
Enhanced network efficiency
Measurements made by Ericsson in live networks have shown that keeping devices in the URA_PCH state – rather than allowing them to drop back to idle mode each time a data transfer is completed – reduces the number of channel establishment requests by more than 50 percent.
Another feature that improves network efficiency is network-controlled Fast Dormancy. Rather than the device deciding by itself when to drop down to idle state – which most smartphones do today – this 3GPP-standardized feature returns control to the network. This improves overall efficiency by preventing repeated dormancy and reconnection requests.
Two enhancements to the Cell_FACH state are available to provide faster access to higher throughput for the short connections needed by chatty applications. Known a s HS_FACH and EUL_FACH, these ‘intermediary’ states allow the operator to keep more data users in the lower states, while giving them a ‘snappier’ experience of social networking and similar applications.
By optimizing their signaling system in this way, and dimensioning the signaling capacity where needed, operators can ensure they deliver the best smartphone user experience while maintaining an efficient network.
Posts
No comments: