In order to simplify the decoding algorithm, it is usually assumed in previously reported work on... more In order to simplify the decoding algorithm, it is usually assumed in previously reported work on space-frequency block coded orthogonal frequency division multiplexing (SFBC-OFDM) systems utilizing space-time block codes (STBC) that the frequency responses of adjacent subchannels are approximately constant for a STBC block length (K.F. Lee and D.B. Williams, 2000). Under this assumption, the conventional linear decoder proposed for STBC in V. Tarokh et al. (1999) can be equivalently used in SFBC-OFDM systems to achieve the maximum diversity gain with the lowest computational complexity. However, this assumption is not accurate when the number of OFDM sub-carriers is small or the system operates in a severe multipath environment. The conventional decoder will give rise to interference due to the channel frequency response variations in adjacent subchannels. This result in an irreducible error floor in the high signal-to-noise ratio (SNR) region of the bit error rate (BER) curve and decreased diversity gain. In this paper, we propose a parallel interference cancellation (PIC) detection scheme with inner and outer iterations for G4 (V. Tarokh et al., 1999) coded SFBC-OFDM transmit diversity systems over frequency selective fading channels. Simulation results will show that the proposed scheme can mitigate the interference effect and make the error floor occur at a very low BER, which can be neglected
... 1, n jl j l jjl a k P k A k z Ĥ (6) 1, 1, 1, n li ii i l iil ii i n n ji j ji j j ji j ji aka... more ... 1, n jl j l jjl a k P k A k z Ĥ (6) 1, 1, 1, n li ii i l iil ii i n n ji j ji j j ji j ji akak P k B k N ak P k N ak P k ak P k z z z § · § · ¨ İ ı İ ı Ĥ Ĥ Ĥ (7) ... In all these diagrams zero power is shown as black; full power as white, with equal power allocated to all channels appearing as dark red. ...
We present bounds and estimates of the uplink spectral efficiency of cellular systems employing v... more We present bounds and estimates of the uplink spectral efficiency of cellular systems employing various multiple access schemes, in particular TDMA and CDMA in conjunction with FEC coding. We determine the cumulative distribution function of co-channel interference using a Monte Carlo technique and use this in conjunction with Shannon's (1949) bound on channel capacity to obtain upper bounds. Estimates are also obtained using simulated performance of practical codes. We show that coded TDMA with 100% re-use gives a greater capacity than with cluster size 3, and that CDMA with voice activation has approximately twice the capacity of either. Adaptive TDMA is identified as promising scheme for further capacity improvement
From the Book: Preface It is superfluous to expatiate here on the importance of wireless communic... more From the Book: Preface It is superfluous to expatiate here on the importance of wireless communications in the modern world. However, the central role of modulation and coding in wireless communications is the main subject of this book. Modulation and coding provide the fundamental link between the user (the customer) and the wireless channel, and determine the performance of the system and its use of the resources of bandwidth and signal power. I write this preface shortly after the auction of the third generation mobile radio spectrum in the UK for in excess of £20 billion, after which no one can doubt the monetary value of these resources! This book, then, is concerned with the principles of modulation and coding as they apply to wireless systems (although other systems are also mentioned), and with the actual modulation and coding schemes that are found in modern wireless systems. It is therefore pitched at a somewhat higher level than most introductory undergraduate textbooks on communications, in order to provide the necessary theoretical underpinning for these schemes. In fact, the book has developed from the notes of a successful MSc module (also taken as a week-long stand-alone short course for industry), which I have taught for some years at the University of York and elsewhere. This in turn developed from a final year MEng course on 'Advanced Modulation and Coding' at York, as well as from 15 years of research in wireless communications. The book is thus aimed primarily at final year undergraduate or Master's level postgraduate students, with the implications that some prior exposure to basic communication principles would be helpful. In an academiccontext, then, I hope it will support courses towards the end of a Bachelor's program (or an equivalent first degree in Europe), or Master's level courses or in support of Doctoral programmes. While it is designed as an integrated whole, many of the chapters will stand alone, so it could also be used in courses on modulation or coding only. However, it is also my hope that it will be suitable for practising communications engineers, both to provide an introduction to the more advanced topics in this area, and also to give practical guidance in developing and applying the schemes described. To this end a number of practical examples are included, as well as tables and graphs and a full chapter on implementation issues. The implicit premise behind the book is that modulation and coding are best regarded as a single process, rather than as two separate processes. This implies not only that they should be implemented jointly, but also that they should be taught jointly. We then find, serendipitously, that there are a plethora of common principles between the two aspects, which greatly aid understanding. It also provides a natural basis for such techniques as coded modulation and coded orthogonal frequency division multiplexing (OFDM), in which coding and modulation are inextricably combined. Modulation and (especially) coding are notorious for being heavily mathematical subjects. I suspect this reputation is not entirely accurate—or it would be beyond my understanding! I have, therefore, tried to keep the mathematical content of the book to an absolute minimum (but now below!), and to make use of graphical and verbal explanations of the sort I have myself found helpful. Mathematics has been included either where it actually aids understanding, or where it is essential to allow numerical calculations. Detailed derivations of results have generally been omitted, with reference to the original literature for the interested reader. In a couple of cases mathematical detail has been relegated to appendices. An important motivation for the book has been to provide the basis for understanding the modulation and coding schemes actually used in modern wireless systems, and as mentioned above, this has largely dictated the level of the book. With such a rapidly developing field, however, it is impossible to keep up, and there have been some significant developments even during the gestation of the book which I have had to leave out. However, I have been able to include such advanced techniques as OFDM and turbo-codes, which are now appearing in 'live' systems and which are not well covered in other texts. Other content, such as the effect of multipath and of non-linear amplifiers, is peculiar to wireless systems and again is not often included in books of this sort. I should emphasize here, however, that 'coding' in this book refers to error control coding, and in particular to forward error correcting coding. Other very important types of code, such as speech/video coding and cryptography, are outside its scope. The book is accompanied by a Companion Web Site, hosted by Pearson Education at www.booksites.net/burr. This will include a variety of material, which I hope will helpfully supplement the book. In particular it will include worked solutions to the problems,…
Elektrotechnik Und Informationstechnik, Nov 1, 2002
Turbo-codes are by now well-known as a computationally-feasible coding scheme able to attain capa... more Turbo-codes are by now well-known as a computationally-feasible coding scheme able to attain capacities very close to the Shannon bound for the scalar (single-input, single-output) channel. Recently it has been shown that much greater capacities are possible on wireless MIMO (multiple-input, multiple-output) channels, attained by means of space-time codes. The proposed paper will review the application of turbo-codes to these channels, proposing an encoding scheme, together with criteria for optimum performance and decoding techniques based on the iterative decoding algorithm used conventionally for turbo-codes. Performance competitive with other published schemes is attained.ZusammenfassungTurbo-Codes bieten die Möglichkeit, Übertragungskanäle mit vertretbarem Aufwand fast bis zur theoretischen Grenze der Shannon’schen Kanalkapazität auszunützen. In letzter Zeit wurde gezeigt, dass die Kanalkapazität von Funkkanälen durch Verwendung von mehreren Antennen-Elementen beim Sender und beim Empfänger im Vergleich zu Übertragungssystemen mit nur einer Antenne an jedem Ende der Übertragungsstrecke wesentlich erhöht werden kann. In diesem Beitrag wird ein neues Verfahren vorgeschlagen, wie Turbo-Codes sehr effizient in solchen Mehr-Antennensystemen eingesetzt werden können und welche Ergebnisse dabei erzielt werden.
Future wireless communication in 5G and beyond will use millimetre waves (mmWave) because of the ... more Future wireless communication in 5G and beyond will use millimetre waves (mmWave) because of the available bandwidth: however this requires directional antenna gain to overcome the pathloss in these bands. This paper explores the significant issue of multipath propagation characteristics for mm Wave communication. We propose the novel distinction between the effective and the environmental K-factor for Ricean channels, and we further derive an approximation in closed form for the effective K-factor for the one ring scattering channel model, and corroborate it by comparison with simulation results.
Enhanced mobile broadband (eMBB) wireless communications in 5G and beyond will use millimetre-wav... more Enhanced mobile broadband (eMBB) wireless communications in 5G and beyond will use millimetre-wave bands because of the bandwidth available, but this will require multi-element arrays to provide the antenna gain required to overcome the path loss in these bands. In this paper we consider the use of multiple arrays to provide distributed beamforming to serve multiple users, using a simplified precoding approach based on zero forcing to avoid inter-user interference. We also consider the effect of Ricean fading using a simple ring-of-scatterers model, and show that the Rice factor observed by the user is increased due to the effect of beamforming
Using token passing and carrier sense multiple access (CSMA) as examples we show how routing in r... more Using token passing and carrier sense multiple access (CSMA) as examples we show how routing in radio LANs can be implemented. For the case of token passing we present numerical results on the performance of the combined routing and channel access protocol, obtained using Monte Carlo simulation. (6 pages)
In order to simplify the decoding algorithm, it is usually assumed in previously reported work on... more In order to simplify the decoding algorithm, it is usually assumed in previously reported work on space-frequency block coded orthogonal frequency division multiplexing (SFBC-OFDM) systems utilizing space-time block codes (STBC) that the frequency responses of adjacent subchannels are approximately constant for a STBC block length (K.F. Lee and D.B. Williams, 2000). Under this assumption, the conventional linear decoder proposed for STBC in V. Tarokh et al. (1999) can be equivalently used in SFBC-OFDM systems to achieve the maximum diversity gain with the lowest computational complexity. However, this assumption is not accurate when the number of OFDM sub-carriers is small or the system operates in a severe multipath environment. The conventional decoder will give rise to interference due to the channel frequency response variations in adjacent subchannels. This result in an irreducible error floor in the high signal-to-noise ratio (SNR) region of the bit error rate (BER) curve and decreased diversity gain. In this paper, we propose a parallel interference cancellation (PIC) detection scheme with inner and outer iterations for G4 (V. Tarokh et al., 1999) coded SFBC-OFDM transmit diversity systems over frequency selective fading channels. Simulation results will show that the proposed scheme can mitigate the interference effect and make the error floor occur at a very low BER, which can be neglected
... 1, n jl j l jjl a k P k A k z Ĥ (6) 1, 1, 1, n li ii i l iil ii i n n ji j ji j j ji j ji aka... more ... 1, n jl j l jjl a k P k A k z Ĥ (6) 1, 1, 1, n li ii i l iil ii i n n ji j ji j j ji j ji akak P k B k N ak P k N ak P k ak P k z z z § · § · ¨ İ ı İ ı Ĥ Ĥ Ĥ (7) ... In all these diagrams zero power is shown as black; full power as white, with equal power allocated to all channels appearing as dark red. ...
We present bounds and estimates of the uplink spectral efficiency of cellular systems employing v... more We present bounds and estimates of the uplink spectral efficiency of cellular systems employing various multiple access schemes, in particular TDMA and CDMA in conjunction with FEC coding. We determine the cumulative distribution function of co-channel interference using a Monte Carlo technique and use this in conjunction with Shannon's (1949) bound on channel capacity to obtain upper bounds. Estimates are also obtained using simulated performance of practical codes. We show that coded TDMA with 100% re-use gives a greater capacity than with cluster size 3, and that CDMA with voice activation has approximately twice the capacity of either. Adaptive TDMA is identified as promising scheme for further capacity improvement
From the Book: Preface It is superfluous to expatiate here on the importance of wireless communic... more From the Book: Preface It is superfluous to expatiate here on the importance of wireless communications in the modern world. However, the central role of modulation and coding in wireless communications is the main subject of this book. Modulation and coding provide the fundamental link between the user (the customer) and the wireless channel, and determine the performance of the system and its use of the resources of bandwidth and signal power. I write this preface shortly after the auction of the third generation mobile radio spectrum in the UK for in excess of £20 billion, after which no one can doubt the monetary value of these resources! This book, then, is concerned with the principles of modulation and coding as they apply to wireless systems (although other systems are also mentioned), and with the actual modulation and coding schemes that are found in modern wireless systems. It is therefore pitched at a somewhat higher level than most introductory undergraduate textbooks on communications, in order to provide the necessary theoretical underpinning for these schemes. In fact, the book has developed from the notes of a successful MSc module (also taken as a week-long stand-alone short course for industry), which I have taught for some years at the University of York and elsewhere. This in turn developed from a final year MEng course on 'Advanced Modulation and Coding' at York, as well as from 15 years of research in wireless communications. The book is thus aimed primarily at final year undergraduate or Master's level postgraduate students, with the implications that some prior exposure to basic communication principles would be helpful. In an academiccontext, then, I hope it will support courses towards the end of a Bachelor's program (or an equivalent first degree in Europe), or Master's level courses or in support of Doctoral programmes. While it is designed as an integrated whole, many of the chapters will stand alone, so it could also be used in courses on modulation or coding only. However, it is also my hope that it will be suitable for practising communications engineers, both to provide an introduction to the more advanced topics in this area, and also to give practical guidance in developing and applying the schemes described. To this end a number of practical examples are included, as well as tables and graphs and a full chapter on implementation issues. The implicit premise behind the book is that modulation and coding are best regarded as a single process, rather than as two separate processes. This implies not only that they should be implemented jointly, but also that they should be taught jointly. We then find, serendipitously, that there are a plethora of common principles between the two aspects, which greatly aid understanding. It also provides a natural basis for such techniques as coded modulation and coded orthogonal frequency division multiplexing (OFDM), in which coding and modulation are inextricably combined. Modulation and (especially) coding are notorious for being heavily mathematical subjects. I suspect this reputation is not entirely accurate—or it would be beyond my understanding! I have, therefore, tried to keep the mathematical content of the book to an absolute minimum (but now below!), and to make use of graphical and verbal explanations of the sort I have myself found helpful. Mathematics has been included either where it actually aids understanding, or where it is essential to allow numerical calculations. Detailed derivations of results have generally been omitted, with reference to the original literature for the interested reader. In a couple of cases mathematical detail has been relegated to appendices. An important motivation for the book has been to provide the basis for understanding the modulation and coding schemes actually used in modern wireless systems, and as mentioned above, this has largely dictated the level of the book. With such a rapidly developing field, however, it is impossible to keep up, and there have been some significant developments even during the gestation of the book which I have had to leave out. However, I have been able to include such advanced techniques as OFDM and turbo-codes, which are now appearing in 'live' systems and which are not well covered in other texts. Other content, such as the effect of multipath and of non-linear amplifiers, is peculiar to wireless systems and again is not often included in books of this sort. I should emphasize here, however, that 'coding' in this book refers to error control coding, and in particular to forward error correcting coding. Other very important types of code, such as speech/video coding and cryptography, are outside its scope. The book is accompanied by a Companion Web Site, hosted by Pearson Education at www.booksites.net/burr. This will include a variety of material, which I hope will helpfully supplement the book. In particular it will include worked solutions to the problems,…
Elektrotechnik Und Informationstechnik, Nov 1, 2002
Turbo-codes are by now well-known as a computationally-feasible coding scheme able to attain capa... more Turbo-codes are by now well-known as a computationally-feasible coding scheme able to attain capacities very close to the Shannon bound for the scalar (single-input, single-output) channel. Recently it has been shown that much greater capacities are possible on wireless MIMO (multiple-input, multiple-output) channels, attained by means of space-time codes. The proposed paper will review the application of turbo-codes to these channels, proposing an encoding scheme, together with criteria for optimum performance and decoding techniques based on the iterative decoding algorithm used conventionally for turbo-codes. Performance competitive with other published schemes is attained.ZusammenfassungTurbo-Codes bieten die Möglichkeit, Übertragungskanäle mit vertretbarem Aufwand fast bis zur theoretischen Grenze der Shannon’schen Kanalkapazität auszunützen. In letzter Zeit wurde gezeigt, dass die Kanalkapazität von Funkkanälen durch Verwendung von mehreren Antennen-Elementen beim Sender und beim Empfänger im Vergleich zu Übertragungssystemen mit nur einer Antenne an jedem Ende der Übertragungsstrecke wesentlich erhöht werden kann. In diesem Beitrag wird ein neues Verfahren vorgeschlagen, wie Turbo-Codes sehr effizient in solchen Mehr-Antennensystemen eingesetzt werden können und welche Ergebnisse dabei erzielt werden.
Future wireless communication in 5G and beyond will use millimetre waves (mmWave) because of the ... more Future wireless communication in 5G and beyond will use millimetre waves (mmWave) because of the available bandwidth: however this requires directional antenna gain to overcome the pathloss in these bands. This paper explores the significant issue of multipath propagation characteristics for mm Wave communication. We propose the novel distinction between the effective and the environmental K-factor for Ricean channels, and we further derive an approximation in closed form for the effective K-factor for the one ring scattering channel model, and corroborate it by comparison with simulation results.
Enhanced mobile broadband (eMBB) wireless communications in 5G and beyond will use millimetre-wav... more Enhanced mobile broadband (eMBB) wireless communications in 5G and beyond will use millimetre-wave bands because of the bandwidth available, but this will require multi-element arrays to provide the antenna gain required to overcome the path loss in these bands. In this paper we consider the use of multiple arrays to provide distributed beamforming to serve multiple users, using a simplified precoding approach based on zero forcing to avoid inter-user interference. We also consider the effect of Ricean fading using a simple ring-of-scatterers model, and show that the Rice factor observed by the user is increased due to the effect of beamforming
Using token passing and carrier sense multiple access (CSMA) as examples we show how routing in r... more Using token passing and carrier sense multiple access (CSMA) as examples we show how routing in radio LANs can be implemented. For the case of token passing we present numerical results on the performance of the combined routing and channel access protocol, obtained using Monte Carlo simulation. (6 pages)
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