This is a guest post from Warren Dumanski, vice president of sales and marketing at Newfield Wireless.

Most people in the wireless ecosystem understand the inherent value proposition of LTE: more efficient spectrum utilisation and better end-to-end QoS capabilities due to its new internet protocol (IP) network architecture. What many don’t understand is that the initial deployments of LTE, which consider all sessions as data, do not support voice calls “as data”.  Note: We are excluding over-the-top (OTT) calls made through Skype, Google Talk and others as these would be seen as any data application by the network, but are also typically understood to be best-effort services as opposed to “toll-quality” voice expected by most  mobile subscribers.

Until an operator deploys VoLTE, LTE voice calls are supported in the 3G network through an implementation known as Circuit Switched Fallback (CS Fallback) in 3GPP networks. While CS Fallback is an interim measure via core network upgrades until a more robust VoLTE implementation is deployed, operators currently employing the strategy in their initial LTE networks are often unaware of the unintended consequences on their LTE and 3G network.

When a subscriber on the LTE network makes or receives a voice call, the network redirects the device to the 3G network where the voice call is attempted. Upon completion of the voice call and any active data session, the device must reselect the LTE network. An unintended consequence of this standardised approach to call completion is that if an LTE subscriber is using an application (e.g., Facebook) on the 4G network at the time of the call, both the voice and data session are moved back to the 3G network. Perhaps even more troubling to the network operator, until the data session is completed or the user equipment (UE) is reset, the subscriber will camp on the 3G network.

This has a whole host of ramifications to the LTE operator employing CS Fallback, including:

–          Underutilisation of their LTE network, represented by islands of unused capacity

–          Poor data network performance with UEs unknowingly camped on 3G networks

–          Subscriber perception that 4G data experience is no better than that offered by 3G

Until recently, operators were “in the dark” about the real performance of their LTE network. However, applications such as TrueCall LTE from Newfield Wireless, provide network operators with a harmonised view of their 4G/3G networks. These types of applications will enable an LTE operator to:

–         Understand the critical handoff zones in and out of 4G

–          Know where LTE subscribers are camping on 3G networks

–          Evaluate how much data capacity is really being provided by its LTE network for any given area

Like any new technology, there are bound to be challenges in initial LTE network deployments. Thankfully, the shortcomings of CS Fallback can be addressed by network engineers enabled with a complete understanding of their LTE subscriber experience through advanced visualisation and optimisation solutions.

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