Cisco talks QoS issues, virtualization potential
The drive toward network simplicity continues to run up against the need for mobile operators to support two separate networks in order to handle voice traffic (2G/3G) and growing data demand (LTE).
The solution everyone is looking to move toward is running voice traffic over data networks, whether LTE or Wi-Fi. However, challenges remain before such a seemingly simple move can be made.
The biggest challenge is ensuring a level of service quality consumers have come to expect from 2G/3G-based cellular services. While often not perfect when compared with landline voice services, consumers have been trained over the past 30 years to expect a certain experience when using their cellular phone to make voice calls.
Mobile operators and their equipment vendors appear to be making strides in this space, with some carriers having already begun rolling out voice over LTE and voice over Wi-Fi services.
RCR Wireless News spoke with Dan Kurschner, marketing manager of Cisco’s service provider mobility business, to gain insight into how the vendor community is progressing in terms of supporting VoLTE and VoWi-Fi, as well as what challenges remain to be tackled.
RCR Wireless News: How important is the transition of mobile voice traffic to data networks for mobile operators?
Dan Kurschner: VoLTE is a necessity for an LTE network as there is no more dedicated circuit-switch domain for carrying voice in LTE. While mobile operators can still rely on the 3G/2G network for voice, with LTE roll out they are looking at limiting the investment on legacy 2G and 3G networks. Adding more coverage for LTE is expensive.
VoWi-Fi:
• Complements indoor macro radio VoLTE coverage for residential and enterprise
• Offers international VoIP roaming.
• Offers voice on non-SIM devices (like a Wi-Fi-only iPad)
RCRWN: What are some of the biggest challenges for this transition?
DK: For VoWi-Fi the biggest challenges are handsets, mobility and quality of service. The requirement of a VoIP client in handsets and lack of Wi-Fi mobility has been one of the obstacles for VoWi-Fi. Apple’s iOS 8 Wi-Fi calling solves part of the problem by offering a native VoIP client (VoWi-Fi and cellular voice use the same phone application) and VoLTE/VoWi-Fi mobility. It is expected the world of Android will follow soon.
We have also seen reluctance from some operators to use Wi-Fi technology. They look at it as potentially opening the door to over-the-top competition for voice. Some operators have expressed that they could become a generic roaming system between Wi-Fi locations where most users spend most of their time: at the home and office. Other operators have discussed limiting voice over Wi-Fi to on-campus enterprise accounts, or via operator-owned “trusted” Wi-Fi hot spots. The technology to leverage Wi-Fi has been around for a while. Apple’s move coupled with some aggressive, forward-looking operators is effectively pushing legacy operators to change.
RCRWN: How well are mobile operators and their vendor partners doing in handling the QoS issues that seems to be of most concern for VoLTE and VoWi-Fi?
DK: For VoLTE, Cisco has extensive capabilities to deliver QoS. These solutions are currently in place with almost all of the LTE operators using Cisco solutions. We leverage our policy systems as well as third parties to set up dedicated bearers on LTE for VoWi-Fi. If we lose LTE coverage we can fall back to 3G or, if available, VoWi-Fi.
For VoWi-Fi, mobile operators are looking at limiting the Wi-Fi networks that are allowed to have VoWi-Fi in the near term. In this way only the Wi-Fi networks with QoS acceptable to the mobile operator is allowed. Cisco is working on solutions that can bring forth the best VoWi-Fi QoS/quality of experience.
RCRWN: How important is policy control in this move toward voice over data networks?
DK: Policy control is critical for QoS control in voice over data. Dedicated bearers often used in VoLTE and VoWi-Fi rely on policy control to establish connections.
RCRWN: What changes/challenges are needed to handle these policy control needs?
DK: The mobile device and the Wi-Fi network need to indicate to the gateway the capabilities to handle VoWi-Fi traffic. Much of this technology is available in Hot Spot 2.0 and ANDSF.
RCRWN: What challenges remain for bridging the gap between handing off voice traffic over licensed and unlicensed data networks?
DK: There are similarities and differences in terms of QoS for VoLTE and VoWi-Fi. Both VoLTE and VoWi-Fi rely on session initiation protocol-based IP multimedia subsystems for call control and evolved packet core for bearer. End-to-end QoS can be archived in VoLTE by leveraging the LTE radio access network together with EPC for QoS. However, in VoWi-Fi there are differences as Wi-Fi in general has much less QoS capabilities. Cisco is working on VoLTE QoS from an end-to-end perspective.
RCRWN: What impact will virtualization have on VoLTE, VoWi-Fi plans?
DK: Virtualization offers the flexibility for our software to reside on varied hardware platforms. This allows operators to customize the install to suit their needs. We are coupling or virtualizing solutions with advanced orchestration and automation systems for both the new virtualized systems as well as existing hardware based solutions like switches and routers. VoLTE IMS/telecommunication application server core and VoWi-Fi evolved packet data gateway and EPC can benefit from virtualization. Cisco has a virtualized telco cloud solution for VoLTE and a virtualized packet core based on our StarOS software. These solutions address both VoLTE and VoWi-Fi virtualization requirements.
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