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HD Voice: What Does It Mean To You?

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These days we do a lot more than making calls on our mobile handsets. Many spend much more time on internet browsing or instant messaging than using the device for calling someone. But that doesn’t mean we shouldn’t see any innovation on the voice call front; given the ultimate purpose of phones, is to call others. In the last few weeks Mobile HD Voice has been one of the much publicised topics in the country. As the name suggests, we are talking about high quality voice calls in mobile networks, with an improved user experience.

A new innovation?

HD Voice service was first introduced to Sri Lanka by Dialog, back in early 2012. Dialog was the 42nd operator, globally, to introduce the service to their customers. Last month Etisalat became the second operator in Sri Lanka (and 107th operator globally) to add this feature to their network offerings. So, clearly it is not entirely new to Sri Lanka.

So what exactly does HD Voice mean? And how does it work?

To start with, HD Voice is an umbrella term that refers  to the technologies that enhance the quality of an audio call (or even the ‘audio’ part of a video call). Yes, that means there are more than one technology used together or separately to achieve the ¨HD Voice functionality¨…or rather the improvement.

HD Voice improves the quality of the voice call. It provides more natural sounding calls. HD Voice also helps people hear better in noisy environments by reducing the background noise, using noise cancelling techniques. Which means, with HD Voice, your caller’s voice will sound less robotic and you will be able to differentiate between ‘s’ and ‘f’ easily. Overall HD Voice improves the user experience. This is not something new. VoIP services like Skype has been using such feature for a long time and probably you have used it too, but we are talking about bringing the feature to mainstream mobile voice communication.

The technology behind HD Voice

There are three mechanisms that are widely used to achieve the HD Voice functionality.

Frequency Range: Narrowband vs Wideband. (Image Source: road2it)

Frequency Range: Narrowband vs Wideband. (Image Source: road2it)

First, doubling the audio bandwidth. Instead of limiting a voice call to the current narrow-band frequency range of 300 Hz and 3.4 KHz, HD Voice makes use of Wideband audio technology that transmits at the range of 50 Hz to 7 KHz. To achieve this, operators use an audio codec called Adaptive Multi-Rate Wideband (AMR-WB), which doubles the audio bandwidth compared to traditional  telephony. In ITU Telecommunication Standardization Sector (ITU-T) terms AMR-WB is codified as G.722.2 codec.

Secondly, improved acoustic design. This is more or less something that the device manufacturers need to focus on. Since HD Voice utilizes greater bandwidth with the help of AMR-WB codec, the devices too need to be designed in a way to utilize the greater bandwidth offered to them. Here’s where acoustic design comes into play. Components like the microphone and speaker need to be of good quality and they need to be well integrated to the device, in such a way to optimize the HD voice features.

Thirdly, redesigned signal processing algorithms. Processing of the audio (in the background ) is an essential part of the whole process. The algorithms that handle this part, are capable of handling higher ‘sampling rate’ compared to regular voice calls. Regular voice calls take 8000 audio samples per second (8 KHz) to process the call. In HD Voice it is doubled to 16000 audio samples per second (16 KHz). Hence, users will be able to hear ‘more details’ from a person’s voice. Another algorithm used in this process is a noise suppressor. This helps in reducing the background noise while a person is using HD Voice.

Global availability

According to the latest report published by Global mobile Suppliers Association (GSA) on 2nd June 2014, 109 mobile operators across 73 countries around the world have launched the HD Voice service for public. And Sri Lanka is one of the 22 countries which has more than one operator offering the service.

HD Voice: Global Availability. (Image Courtesy: Global Mobile Suppliers Association)

HD Voice: Global Availability.
(Image Courtesy: Global Mobile Suppliers Association)

As I mentioned before, Dialog (the largest mobile service provider in Sri Lanka) introduced the service on their 3G/HSPA network back in February, 2012. Etisalat joined the club last month (May 2014) by upgrading their 3G/HSPA framework with this capability. On GSM/HSPA platforms, all it takes the operator is to upgrade their existing network infrastructure(i.e no need to add new base station components), in order to offer HD Voice service. Since HD Voice feature is an upgrade to the operators existing infrastructure, they will not be charging you extra for the service. You will be charged the regular rates when you make a call, while the call quality gets better. Sounds cool, right? Well, read further!

Requirements to experience HD Voice

That brings us to the important part. As an end user (customer/ subscriber) what does it take you to experience mobile HD? Well there are few requirements.

1- Your phone and the phone on the other end need to be HD Voice compatible.

Imagine this like calling someone on Skype. Just like you both need to have Skype installed on your devices to make the video call, both devices need to be ‘HD Voice compatible’ to use the HD Voice service offered by your mobile service provider.
According to GSA report of March, 2014, there are at-least 329 mobile phones from 19 manufacturers that support HD Voice (AMR-WB, currently available. Most of the new devices introduced daily, are compatible with the feature. You can have a look at the device list here.

Does my phone needs to be a smartphone?

Not really. AMR Wideband was first developed by Nokia. HD Voice technology was first implemented in 2009, when the number of smartphones were limited. And Nokia was one of the first manufacturer to integrate the technology in their handsets including the ones that ran S40 and Symbian S60 OS. Hence, your device does not need to fit into ‘smartphone’ category to experience HD voice. But it should be compatible with AMR-WB. Most new devices released these days support it. (So, in my opinion, ‘lack of smartphones in the market’ is not the only reason for ‘less public awareness’ about the service, over the years). Given many phones don’t come with extensive user manuals these days, you can simply Google the model name or refer to this list provided by GSA to check the availability of AMR-WB on your device.

2- Both devices need to be connected to HD capable base station

Both the caller and receiver need to be connected to the HD Voice capable base station of their respective network. In Sri Lanka’s case it should be 3G/HSPA stations of Dialog and Etisalat since both networks support HD Voice over 3G/HSPA network. (Instead of GSM(2G) or LTE).

Does that mean you need to be connected HSPA (Data)?

No. Actually some media outlets have reported that you have to be connected to 3G (as in data) to experience this. Even Etisalat’s media report claims you need to be ‘connected to 3G’ – but what they actually mean is that you need to be connected to a 3G capable  base station.

This should not be confused with VoLTE or Voice over LTE which puts voice and data in a single radio layer. Here calls are carried over IP technology (same as data) instead of circuit switched path (regular calls) used in HSPA networks like Dialog or Etisalat. VoLTE supporting networks are currently limited  to 8 worldwide, and VoLTE supporting device are limited too. LTE offered by Sri Lankan networks is limited to data only at the moment. (i.e – you can’t make voice calls when your network mode is set to ‘LTE Only’ on Dialog or Mobitel)

Again, just because your carrier supports HD voice does not mean they support it all around the country. Reason is, there are places that have only GSM(2G) base stations instead of HSPA ones. So if your device is connected to a 3G base station and your friend’s is not, even though you both have compatible devices, then you will not be able to experience it.

Interoperability: Another less publicised, but very important requirement for HD Voice is that when the call involves two different networks, they both need to be using HD Voice on compatible network modes in-order for HD Voice to work. (Wait, what?) Yes, that is because HD Voice technology is not inter-operable at the moment. At the time of writing, as I mentioned above, both Etisalat and Dialog support HD voice on their HSPA network. But, I have not got enough data that confirms that both networks are compatible with each other. Which means there is a chance that caller and receiver need to be on the same network to experience the feature. The problem widely exists in the US since different networks support HD Voice in different modes like GSM, CDMA and LTE. And not many devices are compatible with all these modes. Now, you know why HD Voice has not got great public attention over the years. That is because not many people have been able to experience it even though they have a compatible phone and they are on a compatible network.

Growth of HD Voice (Image Courtesy: Global Mobile Suppliers Association)

Growth of HD Voice
(Image Courtesy: Global Mobile Suppliers Association)

So that brings us to the important question…is HD Voice another gimmick?

I will safely say it is not. It has been practically proved that HD Voice improves user experience by increasing call quality and reducing background noises. (Simply do a YouTube search to check some demos). In my opinion it should be supported by default on all handsets and all networks should adopt to it. What is keeping us behind is the compatibility issues, which is a shame.

What does the future hold?

Sri Lanka has been one of the first countries to bring latest mobile innovations to public, thanks to our wonderful service providers (yes, seriously). We are one of the first to have LTE in the region. VoLTE or Voice over LTE is seen as the next big trend in voice communications. GSA says that Sri Lanka is actually testing this service. I foresee a future where major networks in Sri Lanka adopt to VoLTE that provides seamless connectivity and HD Voice on the same platform without any hassle. It is always good to be optimistic!

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