Showing posts with label Voice Communications. Show all posts
Showing posts with label Voice Communications. Show all posts

Sunday, 29 March 2020

Mobile Voice Communications is neither Dying, nor Dead!

If you have been following the mobile industry for a long time, you could be forgiven for thinking that voice communications is dead. This 2013 article for example talks about the impending death of voice and this 2018 article talks about how smartphones have killed the art of conversation. These are just examples and I have read many similar articles in the last 5-10 years.

The thing is that a lot of unnecessary calls became SMS and messages once the price of SMS and data went down. Similarly, voice ceased to be a differentiator in many markets so they started offering unlimited voice and/or SMS locally. This does not necessarily solve my requirements for international calling so I moved on to Viber, WeChat and WhatsApp.

The annual TeleGeography Report and Database update (just released) estimates that international over-the-top (OTT) voice traffic reached 1 trillion minutes in 2019, compared to just 432 billion minutes of international carrier traffic.

Anyway, with the lockdown in many countries because of coronavirus COVID-19, people have re-discovered the use of voice communications again. While I prefer having meetings on the internet, sometimes it's just simpler to call using your phone. A friend discovered that while she has some 40 GB data allowance that was generally more than enough, working from home means that she is having to use her device as a hotspot that is using up all her data. Switching from OTT calling to unlimited voice calling in her package means that she doesn't have to worry about voice calls eating her data package.

She is not alone. Operators all over are reporting the rise in voice communications:

  • 27 Mar 2020 - O2 UK reported, "Since March 16th we have seen approximately 57% more voice traffic at the busiest point of the day. Typically voice traffic increases 5% year on year, and in a week we have experienced an increase of voice traffic comparable to nine years of regular demand." (link)
  • 26 Mar 2020 - Official numbers reported by CTIA from Verizon, AT&T, T-Mobile, Sprint and U.S. Cellular stated that mobile voice traffic was up 24.3% while mobile data traffic was up 9.2% (see photo above - link)
  • 24 Mar 2020 - Telenor Norwar tweeted, "Traffic has increased sharply since the coronary smith was seriously registered in this country. 50% increase in mobile voice, 25% increase in mobile data and 30-40% increase in fixed broadband"
  • 24 Mar 2020 - T-Mobile USA released some interesting stats including gaming, etc. With regards to voice, their announcement said, "People are talking and texting more. Messaging is up dramatically, with a 26% increase in SMS (texting) and a 77% increase in MMS (pictures, multi-party texts, etc.). And, the amount of time people spend on calls has increased 17% nationwide." (link)
  • 20 Mar 2020 - Telia in Denmark reported, "Thursday, March 12, the volume of speech in the network thus increased by 24% compared to the day before. Over the weekend 50% more was spoken - obviously due to a need to gain status on family and friends in the new situation. In the past working week, about 60% more has been spoken on the phone than on a normal week in March." (translated from original)
Is voice important for an operator? Probably not very much in the developed markets where users pay a good amount for data packages. In developing countries, voice is still a good source of revenue. At the TIP summit last year, Malaysian telecom giant Axiata said that ""every gigabyte costs about $1.40 to manufacture...generates only 80 cents in revenue...The 2G voice business currently funds any losses". This is not a long term sustainable model for these operators.


Funnily I just remembered that in a survey of over 1000 people in the USA regarding what they want from 5G, the third most important thing was "clearer voice quality". If you want to understand how voice quality is measured that see this tweet below


We may keep on seeing a boom in voice traffic as more lockdowns occur and they are even stricter. We will have to wait and see of this habit of talking sticks or it's just for this unusual situation.

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Friday, 21 February 2020

EPS Fallback in 5G Standalone Deployments

It can be expected that later this year some mobile network operators will launch their initial 5G standalone (5G SA) deployments.

Nevertheless there will remain areas with temporary or permanently weak 5G NR coverage. One possible reason might be that even when 5G and LTE antennas are co-located, which means: mounted at the same remote radio head, the footprint of the 5G NR cell is significantly smaller when it uses a higher frequency band than LTE - see figure 1.

Figure 1: Smaller footprint of co-located 5G NR cell with higher frequency
Especially UEs making Voice over New Radio (VoNR) calls from the 5G cell edge have a high risk of experiencing bad call quality, in worst case a call drop. To prevent this the UE is forced  during the voice call setup towards 5G core network (5GC) to switch to a LTE/EPS connection where the radio conditions are better for the voice service.

The same procedure for which the term "EPS Fallback" was coined by 3GPP also applies when the UE is served by a 5G cell that is not configured/not optimized for VoNR calls or when the UE does not have all needed VoNR capabilities.

Figure 2: Two options for EPS fallback

When looking at the RAN there are two options for executing the EPS Fallback as shown in figure 2.

In option A the 5G radio connection is released after the initial call attempt is successfully finished and with the 5G RRC Release the UE is ordered to reselect to a 4G cell where a new radio connection is started for the VoLTE call. In this case the UE context is transferred from the AMF to the MME over the N26 interface. 3GPP seems to use also the term "RAT fallback" for this option.

Option B is to perform a 5G-4G inter-RAT handover. Here the session management and user plane tunnels in the core network are handed over from SMF/UPF to MME/S-GW in addition. This is realized with the GTPv2 Forward Relocation procedure on N26 interface.

All in all the EPS fallback is expected to cause an additional call setup delay of approximately 2 seconds.

For the inter-RAT handover case it is easy to detect from signaling information that an EPS fallback was triggered. In the source-eNodeB-to-target-eNodeB-transparent-container sent by the gNB to the eNB a boolean "IMS voice EPS fallback from 5G" indicator will be found that is set to "true". This container is named according to the receiving entity and will be carried by the NGAP Handover Preparation, GTPv2 Forward Relocation Request and the S1AP Handover Request messages.

If a redirection for Voice EPS Fallback is possible or not is indicated in the NGAP Initial Context Setup Request, Handover Request (during 5G intra-system handover) and Path Switch Request Acknowledge (after Xn handover) messages, all sent by the AMF to the gNB.

Further the NGAP protocol provides the cause value "IMS voice EPS fallback or RAT fallback triggered" in the PDU Session Resource Modify Response message indicating that a requested VoNR session cannot be established.  





Sunday, 21 May 2017

Research on Unvoiced Speech Communications using Smartphones and Mobiles

A startup on kickstarter is touting world's first voice mask for smartphones. Having said that Hushme has been compared to Bane from Batman and Dr. Hannibal Lecter. Good detail of Hushme at Engadget here.

This is an interesting concept and has come back in the news after a long gap. Even though we are well past the point of 'Peak Telephony' because we now use text messages and OTT apps for non-urgent communications. Voice will always be around though for not only urgent communications but for things like audio/video conference calls.


Back in 2003 NTT Docomo generated a lot of news on this topic. Their research paper "Unvoiced speech recognition using EMG - mime speech recognition" was the first step in trying to find a way to speak silently while the other party can hear voice. This is probably the most quoted paper on this topic. (picture source).


NASA was working on this area around the same time. They referred to this approach as 'Subvocal Speech'. While the original intention of this approach was for astronauts suits, the intention was that it could also be available for other commercial use. Also, NASA was effectively working on limited number of words using this approach (picture source).

For both the approaches above, there isn't a lot of recent updated information. While it has been easy to recognize certain characters, it takes a lot of effort to do the whole speech. Its also a challenge to play your voice rather than a robotic voice to the other party.

To give a comparison of how big a challenge this is, look at the Youtube videos where they do an automatic captions generation. Even though you can understand what the person is speaking, its always a challenge for the machine. You can read more about the challenge here.

A lot of research in similar areas has been done is France and is available here.


Motorola has gone a step further and patented an e-Tattoo that can be emblazoned over your vocal cords to intercept subtle voice commands — perhaps even subvocal commands, or even the fully internal whisperings that fail to pluck the vocal cords when not given full cerebral approval. One might even conclude that they are not just patenting device communications from a patch of smartskin, but communications from your soul. Read more here.


Another term used for research has been 'lip reading'. While the initial approaches to lip reading was the same as other approaches of attaching sensors to facial muscles (see here), the newer approaches are looking at exploiting smartphone camera for this.

Many researchers have achieved reasonable success using cameras for lip reading (see here and here) but researchers from Google’s AI division DeepMind and the University of Oxford have used artificial intelligence to create the most accurate lip-reading software ever.
Now the challenge with smartphones for using camera for speech recognition will be high speed data connectivity and ability to see lip movement clearly. While in indoor environment this can be solved with Wi-Fi connectivity and looking at the camera, it may be a bit tricky outdoors or not looking at the camera while driving. Who knows, this may be a killer use-case for 5G.

By the way, this is not complete research in this area. If you have additional info, please help others by adding it in the comments section.

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