– The purpose of this paper is to show that a fingerprinting code is a set of code words that are embedded in each copy of a digital object, with the purpose of making each copy unique. If the fingerprinting code is c‐secure, then the decoding of a pirate word created by a coalition of at most c dishonest users, will expose at least one of the guilty parties., – The paper presents a systematic strategy for collusions attacking a fingerprinting scheme. As a particular case, this strategy shows that linear codes are not good fingerprinting codes. Based on binary linear equidistant codes, the paper constructs a family of fingerprinting codes in which the identification of guilty users can be efficiently done using minimum distance decoding. Moreover, in order to obtain codes with a better rate a 2‐secure fingerprinting code is also constructed by concatenating a code from the previous family with an outer IPP code., – The particular choice of the codes is such that it allows the use of efficient decoding algorithms that correct errors beyond the error correction bound of the code, namely a simplified version of the Chase algorithms for the inner code and the Koetter‐Vardy soft‐decision list decoding algorithm for the outer code., – The paper presents a fingerprinting code together with an efficient chasing algorithm.

xxiii 1 Work Context 1 1.1 Definitions and system model . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Overview and contribution of thesis . . . . . . . . . . . . . . . . . . . . 9 2 Information Theory and State of the Art 13 2.1 Information theory viewpoint . . . . . . . . . . . . . . . . . . . . . . . 14 2.1.1 Capacity of the noiseless K-user adder channel . . . . . . . . . . 14 2.1.2 Capacity of the Gaussian multiple access channel . . . . . . . . 14 2.1.3 Capacity of known systems . . . . . . . . . . . . . . . . . . . . . 16 2.1.4 Capacity of multi-antenna system . . . . . . . . . . . . . . . . . 19 2.2 State of the art . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 2.2.1 Multi-user detection . . . . . . . . . . . . . . . . . . . . . . . . 22 2.2.2 Multi-user coding . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.2.3 Multi-antenna and space-time codes . . . . . . . . . . . . . . . . 23 3 Joint Multi-user Decoding 25 3.1 Uncoded two users . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 3.1.1 The Gaussian channel . . . . . . . . . . . . . . . . . . . . . . . 26 3.1.2 The Rayleigh fading channel . . . . . . . . . . . . . . . . . . . . 27 3.2 Convolutional coded systems . . . . . . . . . . . . . . . . . . . . . . . . 30

xiii Chapter

v

this paper, we address Joint Source-Channel (JSC) decoding with low decoding complexity over wireless channel. We propose a unity rate accumulator based design for soft-input soft-out decoding for low complexity Chase-like decoding of arithmetic codes. Chase-like decoding is a low complexity algorithm, where a maximum a posteriori sequence estimation criterion is employed for maximum likelihood decoding of variable length codes like arithmetic codes. Previous contributions propose iterative decoding SISO arithmetic codes with convolutional codes and LDPC codes. We propose application of unity rate accumulator as inner encoder and decoder in the system, which improves the bit error performance of the system by 1.25 dB with same number of decoding iterations. We evaluate the performance of the proposed scheme for image transmission application.

t: The Business Transaction Protocol (BTP) is a carrier-neutral protocol to allow coordination of application work between multiple autonomous, cooperating participants. It defines protocol exchanges to ensure the overall application achieves a consistent result. This consistency may be defined a priori: all the work is confirmed or none is (an atomic business transaction or atom); or it can be determined by application intervention in the selection of the work to be confirmed (a cohesive business transaction or cohesion). The protocol is defined in terms of abstract messages s This specification defines communications protocol bindings to SOAP but als carriage of BTP messages over other communication protocols.

qbstruct-Capacity limits are obtained when binary codes are used for communications over channels in the presence of high levels of interference. The ideal additive Gaussian noise channel and the byleigh fading channel are considered. For each channel,, the performance of four types of decoders are considered. Both binary and channel measurement (soft decision) decoding are considered; for each of these cases, performance results are obtained when interference can and cannot be detected before decoding. Thus, capacity limits for the minimum achievable Eb/No as a function of the code ratel7 are obtained for eight different channel models of interest.

iii List of figures x List of abbreviations xiii List of notations xiv Chapter 1 Introduction 1 1.

Word error rate (WER) performance with soft decision decoding of linear block codes using a trellis is investigated in a Rayleigh fading channel. The signal envelopes corresponding to each bit in a received block are sampled and used for estimating the reliability of the bit. The WER performance is evaluated via laboratory experiments using Hamming (7, 4) code. A great improvement in WER performance can be achieved over conventionally-used minimum distance decoding.

Word error rate (WER) performance with soft decision decoding of linear block codes using a trellis is investigated for noncoherent FSK (frequency-shift keying) in a Rayleigh fading channel. The received signal envelopes corresponding to each bit of the code are sampled and used for estimating reliability of the bits. Hamming

With the rapid increase in the growth of digital broadcast technologies, there has been a demand for high data rate, power, and bandwidth efficient transmission, which, today, is aided by the high-performing low-density parity check (LDPC) codes. In this paper, we explore a novel alternative scheme to the LDPC decoder that performs detection, demodulation, and decoding jointly, coined the joint detector demodulator decoder (JDDD). We test the JDDD through simulation using the modulation schemes defined in the DVB-S2 satellite broadcasting standard. The JDDD is a more recently developed algorithm to the sum–product algorithm (SPA) that is used in decoding the LDPC codes. The JDDD is optimal over a modulated additive white Gaussian noise/intersymbol interference (ISI) channel when resources are sufficient, with the main constraint limiting the algorithm being the availability of computing resources. In this paper, we compare the performance of the system using the JDDD against that of the LDPC decoder. The main result is that the JDDD is able to outperform the iterative detector decoder (IDD) at shorter codeword lengths, when resource requirement is smaller, while the increase in computational requirements tends to favor the IDD at longer CWLs.

Wireless is a term used to describe telecommunications in which electromagnetic waves (rather than some form of wire) carry the signal over part or all of the communication path. Quite a few popular applications over the wireless communication networks get emerged just lately including, cellular telephony, SMS, MMS, world-wide-web browsing as well as video conferencing, to name a few. Data might be damaged during transmission. For reliable communication, error must be detected and corrected. Joint Channel Coding and Cryptography has been analyzed and simulated in this paper. The method is an extension of Soft Input Decryption with feedback, which is used for improvement of channel decoding of secured messages. we utilize the methods for data security as a tool for the detection and correction of transmission errors. Streaming applications are gaining popularity over not only the fixed Internet but also mobile handheld devices. Growth in wireless access technologies along with the advanced coding schemes show the promise of better streaming service for the mobile users. However, wireless channels are characterized by fluctuating bandwidth, thereby making it challenging for streaming applications to ensure good quality of user experience (QoE). In this paper, we adopt an objective approach and propose a cross-layer adaptive streaming technique, where we make use of the channel loss information to update the application layer encoding at a slower rate and the link layer modulation and coding scheme at a faster rate. In our adaptive scheme, we focus on a pause-free playback by preventing buffer underflow at the receiver. Our simulation experiments show that, the proposed adaptive technique improves the QoE of the streaming significantly by gracefully degrading quality in the face of pathological cases such as wireless channel error, while ensuring an uninterrupted services. Keywords— Soft Input Decryption, L-Values, Joint Channel Coding and Cryptography, RSA, coding gain, block length.

Wireless communication systems have found their applications in almost every field of life. Most popular of these applications being web browsing, cellular telephony, SMS, MMS and audio & videoconferencing, just to name a few. There are however a few inherent problems in the communication over a wireless channel. The first one is that it is inherently prone to transmission errors and the second one is the security of data transmitted over the channel. Both the problems are researched separately by researchers, giving separate solutions. Forward error correction mechanisms are under research for error correction at the receiver side and cryptography has been proposed as a mechanism for data security. However these mechanisms have been dealt separately so far. We hereby propose a novel scheme that combines the two mechanisms together i.e. in our scheme we use symmetric cryptography in the form of H-MAC for data integrity protection as well as a means for the detection and correction of transmission errors at the receiver. Simulation results are given for our proposed scheme. This technique is an extension of Soft Input Decryption. Results of simulations of Joint Channel Coding and Cryptography are compared to results of convolutional coding with the same coding rate. We also show that a coding gain is achieved in addition to solving both the outlined problems.

Wireless communication systems are under heavy investigations by the research community, especially since the past decade. Many popular applications over the wireless communication networks have emerged recently including, cellular telephony, SMS, MMS, web browsing and video conferencing, to name a few. Communication over wireless channel, however, is inherently prone to transmission errors. Additionaly efforts have also been made to secure the wireless transmission, using cryptography as a prominent tool. In this paper we introduce a novel method which combines cryptography and error correction together i.e. we utilize the methods for data security as a tool for the detection and correction of transmission errors. To support our research, we provide simulation results obtained using this method which we call as Joint Channel Coding and Cryptography. Joint Channel Coding and Cryptography is an extension of Soft Input Decryption with feedback, which is used for improvement of channel decoding of secured messages. Results of simulations of Joint Channel Coding and Cryptography are compared to results of convolutional coding with the same coding rate. In this way, Joint Channel Coding and Cryptography brings a coding gain of 0.72 dB, while fulfilling security requirements at the same time.

Wireless communication systems and the applications developed for it are increasing day by day, mainly due to the inherent mobility that it offers. Amongst the most popular applications over the wireless communication networks are cellular telephony, web browsing, Simple Messaging Service, Multimedia Messaging Service and video conferencing. Communication over a wireless channel, however, has two inherent problems namely security and transmission errors. Both the issues are researched and dealt separately with sufficient literature available. However these solutions were dealt separately so far. The authors have developed and published earlier some results on the method of joint channel coding and cryptography, which combines data security and error correction by utilizing the data produced by a digital signature scheme, for the correction of transmission errors. This paper takes further the idea of joint channel coding and cryptography and analyses the serial and parallel soft input decryption schemes for joint channel coding and cryptography. We have already shown that joint channel coding and cryptography provides a coding gain over a convolutional code of same rate. Here in this paper we discuss and evaluate the performance of two schemes namely the serial and parallel methods for Soft input decryption and show that the parallel technique provides a further coding gain over the serial scheme.

Wireless communication is undoubtedly one of the most significant advancements by the mankind for improving quality of life. Information is transmitted from one point to another via electromagnetic waves. After Shannon’s landmark paper “A Mathematical Theory of Communication” in 1948, significant advancements have occurred in providing reliable point to point wireless communication. With ever growing need for reliable high speed links, Cooperative communication and Network coding have emerged as viable technologies to bridge the gap. In today’s wireless network, different users have different demands for reliability based on their respective application. In this context, we propose flexible network coding scheme to adapt to user needs. We develop coding rules which achieve maximal diversity of the system, yet provide differentiated class of service to the users. The proposed scheme can be adjusted to accommodate the dynamic changes in quality of service(QoS) demand of users. Second we consider the issue of security in multiple access relay network. Security has always been a primary concern in wireless networks due to it broadcast nature of transmission. The intermediate relay nodes in a wireless network could be modified by adversary to transmit corrupted information. We propose a novel iterative packet recycling methodology which gives performance improvement over traditional approach of discarding received corrupted packets at the destination. Finally, we consider the problem of choosing relay for transmission. We propose a novel selection scheme which provides balanced relay utilization and reduces relay switching rate compared to the traditional selection algorithms. This cuts down energy wastage at the relay and improves the overall network lifetime.

When selecting an error correcting code, it is desired to fulfill a data error rate criterion, but also the code that is selected does this without being excessively complicated. For specific channel conditions it is quite difficult to optimize the error correcting code parameters' analytically. This work proposes multi-objective optimization by applying the Genetic Algorithm (GA) in the selection of Turbo Product Codes (TPC) parameters' that are used for transmission of data over an AWGN channel. The results show that the GA is capable of converging to a set of sensible solutions and giving the pareto-optimum set for error performance against code complexity.

We study the problem of list decoding with focus on the case when we have a list size limited to two. Under this restriction we derive general lower bounds on the maximum possible size of a list-of ...

We study the minimum distance of the binary expansion of high-rate Reed-Solomon (RS) codes and product codes in the polynomial basis and show that the binary codes obtained in this way usually have minimum distance equal to the designed symbol minimum distance. We then show that a judicious choice for the code roots may yield binary expansions with larger binary minimum distance and better asymptotic performance. This result is used to design high-rate RS product codes with significantly lower error floors compared to classical constructions.

We study the decoding of product codes and a class of parallel concatenated product codes (PCPC). PCPC improves the minimum distance while retaining the merit of low decoding complexity of turbo product codes (TPC). We prove that using the Fibonacci interleaver does help increasing the minimum distance. The regularity of the interleaver also reduces the implementation complexity and makes parallel interleaving feasible. We show that Pyndiah's algorithm for decoding product codes produce an annealing effect similar to that of the so-called annealed belief propagation (ABP) algorithms which adjusts the "temperature" of an augmented cost surface. Decoding methods based on modified Pyndiah and annealed BCJR algorithms for both PC and PCPC are proposed and their performance is compared.