Lecture Series in Mobile Telecommunications and Networks (1583KB)

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From plain old Telephony to flawless mobile audio communication Matthew Baker (Philips Research): At the beginning of your presentation, you described the original model for the voice codecs, based around two filters modelling broadly the vocal tract. As we move towards new, higher data rate communication systems, like UMTS LTE, there may perhaps be greater use of the system not for listening to speech but for music and video. Do you see a need for new codec models built around filters or parameterisations perhaps based on musical instruments or other sound sources than the vocal tract? Peter Vary: I have two answers to that. There is a nice European research project called FLEXCODE – like flexible coding. If you type that in your WEB browser, you will end up with the server in Aachen and there is a nice project with KTH, Bastiaan Kleijn and with Nokia Ericsson and France Telecom. We tried to design a universal codec which might be used in the future, which could be the future codec – I don’t know. In the standardisation world, we observe presently the development that we take a standard codec – for example, there is an ITU codec, G.729, which has 8 kbits/s. On top of that bit rate, there is then additional bit rate, up to 12 to 14, 16, 18 up to 32 kbits/s. The add-on, beyond 12 to 14 kbits/s, is transform coding, so what we are seeing there is the base layer. It is a hierarchical coding scheme. If you transmit only the 8 kbits/s you can transmit speech. However, if the affordable bit rate is higher, you can have transparent quality for music. On top of the base layer, there is transform coding – techniques we know from audio coding. The reasoning behind that is that you could imagine, let us say, a broadcast service from a central station, and some of the subscribers have a DSL connection and would like to have the full bit rate, while some just have a GSM phone and they have a reduced bit rate, or just the base layer. For reasons of compatibility, that seems to be a good idea. However, you clearly see a convergence of speech coding and audio coding, which is mostly frequency domain-based coding. John Lowe: This question will involve Mike as well. It is appropriate that Keith Davis is here in particular. From my own background knowledge, Peter, I find what you have talked about this evening very exciting. However, we are in the hallowed halls here where they are doing something much bigger than this particular technology subject, which is encouraging young people to take up engineering. I suspect that the situation in your industry is no different than it is in mechanical engineering, where we have a shortage of young people at whatever level you might choose. Can we use this sort of exciting development to enhance the attraction of young people into engineering? And what, Mike, are Vodafone doing within this industry – and I am not particularly thinking of Vodafone but the industry as a whole – in this country and in others, particularly in Europe, to attract more young people? Can we use this to aid Keith Davis’s efforts, and those efforts taking place at the Institution of Mechanical Engineers and other places? Peter Vary: I can speak for Aachen University, where we have what we call the ‘science truck’. This is a truck which we drive to schools and then demonstrate experiments there, from mechanical engineering, electrical engineering, chemical engineering – all kinds, from all the faculties we have. From my group, we have an experiment there which is called ‘mobile radio’, where the pupils can have hands-on and listen to radio transmissions with bit errors and without bit errors, and vocoders. We try to attract them. We see the problem. We have open days, but we find that it is better to drive to the schools and give some lectures and show some experiments. John Lowe: If I could ask you to be generic, I know that taking technology to schools in individual areas works. I also run an industrial museum and we try to do that, with hands-on works and so on. However, I was looking for the general lessons that we can share across the broader picture. We cannot go into every school with a science truck – and I know our schools reasonably well. Peter Vary: I think we should educate the teachers. In their study schedules, there should be more engineering science, because the teachers do not know enough about engineering. John Lowe: I am really looking for practical help to make that happen. Michael Walker: Exactly on that point of helping the teachers, there is a project in the UK called Project Enthuse, which was started by the Wellcome Trust, and we are a member of that. The idea of Project Enthuse is that we provide continuous professional education to science teachers. We bring science teachers into the National Learning Centre and other places and we send engineers from industry to that centre and show those science teachers how their science is being applied today in industry. They can then take that back to the schools, to make their lessons perhaps more interesting to the pupils, to stimulate them to go on to study science and engineering at university. It aims to add that extra to the course. To go to your specific question, the Academy could take lectures like this, or the key parts of The Royal Academy of Engineering 59
them and perhaps leave out some of the more difficult equations which we didn’t get into here anyway, and take that into the schools. That is basic physics, with a bit of biology there. John Lowe: Thank you. That will do – otherwise we could spend two days discussing this. Professor Jiangzhou Wang (University of Kent): In classes, we teach students that the binaries of speech signal are 3.4 kHz. If my understanding is correct, according to your seminar, the binaries of speech signal should be 7 kHz instead of 3.4 kHz, in order to have good quality for the speech signal. Should we update our lecture notes in the future and teach our students that 3.4 kHz is not enough and that the binary for speech signal should be 7 kHz in order to have a high quality speech signal? What do you think? Peter Vary: I agree, but the reality is that we have the wideband coding standard for ISDN from 1985. The patterns are no longer valid, however, but we now see the first implementation, 20 years later, in DECT. It takes too long. John Ellis (London Artificial Intelligence Club): If doing speculative, blue sky research, would you be doing anything towards quantum computing and entanglement ideas of quantum mechanics, so that a sub-particle over here affects one over there? Peter Vary: That is a good idea, and I showed the picture of the dummy head at the meeting. I had the idea that, if you moved your head, the dummy head should also move. There are lots of improvements you could think about. Michael Walker: Peter, you started off showing a €1 phone, and we know how it got to €1 with standard codecs. Have you done work to look at what actually is the increase in cost and building materials in introducing wideband codecs? Peter Vary: As a university group, we are interested in cost and complexity but we are doing calculations in terms of computational complexity and power consumption. We have a big project at my university called the Cluster of Excellence, and the title is Ultra-High-Speed Mobile Information and Communication. That is a project of 20 chairs at my university, ranging from micro-electronics to applications. We have the guys from computer science there, and also from micro-electronics, and we talk to each other. We are acutely aware that the cost is very critical, and in addition to cost there is energy efficiency and spectral efficiency. We know that we have to improve – and we said the perceived order of magnitude, by one order of magnitude, in terms of bit rate, and not just the bit rate but what you perceive. We also have to improve in terms of costs. So all I would say is yes, at the university, we are really aware of that and we discuss it with our students, but we really cannot make a business plan for Vodafone and tell you how much you will have to invest. Michael Walker: But the costs in terms of complexity is fine, or energy increase – Peter Vary: But by the way, this funny proposal with the hidden bits is due to the awareness of the complexity and costs if you introduce AMR wideband. It is nice to say that we should have it there, but we know that you have to change each base station and the channel codec, which is very expensive. You also have to change the protocols and the transcoding units and so on. It is very expensive, and perhaps this could be a contribution to the discussion, to have cheaper solutions. Michael Walker: If there are no further questions, let me thank Peter for a very stimulating and interesting presentation, and a great conversation or discussion afterwards. I would also like to thank the audience for the very interesting question. Thank you very much. [Applause] 60 The Royal Academy of Engineering
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Lecture Series in Mobile Telecommun
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Foreword This compilation brings to
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From wireless networks to sensor ne
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From wireless networks to sensor ne
Page 9 and 10: As far as the routing of packets is
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Page 23 and 24: Welcome and introduction Professor
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Lecture Series in Mobile Telecommunications and Networks (1583KB)

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