Interview: Head of Strategic Wireless Technology and Core Network, HKT: “The launch of VoLTE is just the beginning of the journey to a new era of mobile voice communications.”

Dr. Henry Wong is head of Strategic Wireless Technology and Core Network at Hong Kong Telecommunications (HK) Limited

Dr. Henry Wong is head of Strategic Wireless Technology and Core Network at Hong Kong Telecommunications (HK) Limited. Here we find out more about how HKT’s network innovations have brought it to the attention of the judges of the LTE Asia Awards, taking place at the Marina Bay Sands on the 24^th September.

You’ve been nominated at the inaugural LTE Asia awards? Why do you think your product attracted the attention of the judges?

Well firstly, being the first operator to launch VoLTE in Kong Kong and the world’s first commercial deployment of the 3GPP R10 eSRVCC technology is a remarkable achievement. However, the main attractions of our service lie in the way we have engineered it and make it different from other deployments so that we can deliver a fully transparent and improved experience for our customer. Key aspects are:

• Improved User Experience on VoLTE over 3G
  • HKT’s Voice over LTE (VoLTE) promises to deliver an elevated experience for users of voice services on LTE. This includes better voice call setup rate, faster call setup time, lower call drop rate, improve in voice quality (MOS), and better Quality of Service.
• VoLTE Call Resume
• HKT’s LTE network can hold VoLTE calls for a short period during PS call re-establishment upon intermittent PS call drop. This will save the user from the need of redialing when encountering radio interruptions.
• eSRVCC (enhanced Single Radio Voice Call Continuity) – enables seamless handover and continuation of voice calls to 3G when user moves out of 4G coverage
• Separate layering for VoLTE and LTE Data
• With better coverage continuity and in-building penetration, HKT uses L1800 as the primary layer to deliver VoLTE service, while data calls are redirected to L2600 for capacity offload.
• This maximizes the service continuity of VoLTE on LTE, while minimizing chances of call interruptions due to handover to different layers or invocation of eSRVCC to 3G.
• Integrated HLR / SAE-HSS / IMS-HSS
• This enables full synchronization of user’s supplementary service setting between 2/3G and VoLTE so as to ensure voice service parity across 2G, 3G and 4G coverage.

What are the main challenges you expect to face over the next 12 months?

The launch of VoLTE is just the beginning of the journey to a new era of mobile voice communications. The key challenge is to build a large VoLTE community in order to maximize the customer benefits. In fact, we have planned the following actions:

• Continue to work with different handset vendors to introduce more VoLTE devices.
• Enable end-to-end IP based VoLTE-to-VoLTE interconnect with other local or overseas mobile networks on VoLTE.
• Enable VoLTE services that can interconnect with HKT’s own VoIP apps and SIP based service on NGN fixed network.
• Enable VoLTE roaming to overseas

By late August 2014, HKT commenced commercial service for VoLTE interconnect between the two separated VoLTE networks of HKT using equipment from two different vendors. While HKT is also working with other HK MNOs for VoLTE local interconnect, we will soon start work on VoLTE interconnect with overseas VoLTE networks and offer International VoLTE Calls in the near future.

What impact do you think VoLTE will have on your customers?

HKT VoLTE lifts the customer experience to a new level in terms of:

• Faster voice call set-up (3G CS voice : ~7s vs VoLTE : ~1s)** – For on-net VoLTE to VoLTE calls
• Improved voice clarity (MOS for 3G CS voice: 3.2 vs VoLTE: 4.2) with significantly reduced background noise
• Improved voice call set-up successful rate from 99.5% to 99.9%
• Improved call drop rate from 0.8% to 0.45%
• Enhanced video call quality to 640 pixel x 480 pixel or above
• Instant switching between voice and video calls

Apart from the above, VoLTE removes the need of CSFB where customers do not need to fall back on 3G for voice call. This not just significantly reduce the call setup time, more importantly, it maintains the data connection on LTE so that the customer can preserve the LTE data experience during and after the call. On the other hand, this not just helps HKT offload the heavily loaded 3G network by shifting voice traffic on LTE, but at the same time reduces chances for users to stay on 3G.

Like other operators, HKT is facing competition from OTTs that are offering multi-media rich services. VoLTE is unique, with a dedicated bearer to protect the voice quality from mixing other traffic loading such as web browsing, video streaming. VoLTE is instrumental in building a modernized IMS core network for HKT that paves the way the evolution of multimedia services.

How have you gone about approaching VoLTE pricing?

HKT is dedicated to continuous improvement of the customer experience by bringing the latest mobile technology its customers. HKT does not charge its customer an additional fee for VoLTE activation, while the VoLTE voice and video calls are charged in the same manner as 3G. This shall give a true seamless experience for customer when migrating onto VoLTE.

What are the next steps for your network after VoLTE?

HKT doesn’t treat VoLTE as a purely voice service but as the foundation for a new IP communications network that delivers services that can be used by integrated apps, web sites and devices. We will continue to explore the opportunities in the mobile IMS space, in order to provide innovative services to our customers across devices. Instant messaging, file transfer, HD video browsing, and video communication will be the mainstream for communication in the future. With the available spectrum on hand, HKT will continue to explore new technologies like LTE-A Carrier Aggregation in order to provide the best experience our customer.

The 9^th annual LTE Asia conference is taking place on the 23rd-25th September 2014 at the Marina Bay Sands, Singapore. Click here to download a brochure for the event.