Improving the Bandwidth Efficiency of Multiple Access Channels Using Network Coding and Successive Decoding PDF Download

Author: Mohammad Jabbari Hagh
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Mohammad Jabbari Hagh
Publisher: LAP Lambert Academic Publishing
ISBN: 9783659454172
Category :
Languages : en
Pages : 132

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In this work, different approaches for improving the bandwidth efficiency of Multiple Access Channels have been proposed. Such improvements can be achieved with methods that use network coding or with methods that implement successive decoding. Both of these two methods have been discussed here. Under the first method, two novel schemes for using network coding in cooperative networks have been proposed. In the first scheme, network coding generates some redundancy in addition to the redundancy that is generated by the channel code. In the second scheme, the relay by use of the network code, sends a compressed version of the parts missing from the original transmission. The second method, involves a scheme to increase the channel capacity of an existing channel. This increase is made possible by the introduction of a new Raptor coded interfering channel to an existing channel. Through successive decoding at the destination, the data of both main and interfering sources is decoded. Finally, we generalize our work to allow the possibility of decoding either the secondary source data or the main source data first. We will investigate the performance and delay for each decoding scheme.

Author: Lele Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 187

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Next-generation wireless networks aim to enable order-of-magnitude increases in connectivity, capacity, and speed. Such a goal can be achieved in part by utilizing larger frequency bandwidth or by deploying denser base stations. As the number of wireless devices is exploding, however, it is inevitable that multiple devices communicate over the same time and same spectrum. Consequently, improving the spectral efficiency in wireless networks with multiple senders and receivers becomes the key challenge. This dissertation investigates low-complexity channel coding techniques that implement canonical random coding schemes in network information theory, such as universal channel coding, superposition coding, rate-splitting, successive cancellation, simultaneous decoding, decode-forward relaying, compress-forward relaying, and Slepian--Wolf coding. In representative communication scenarios, such as compound channels, interference channels, broadcast channels, and relay channels, the proposed channel coding techniques achieve the best known information theoretic performance, some utilizing the recently invented polar codes and some making use of the commercial off-the-shelf codes, e.g., turbo and LDPC codes. These techniques have a potential to become important building blocks towards a general theory of channel coding techniques for the next-generation high-spectral-efficiency, low-power, broad-coverage wireless communication.

Author: Ezio Biglieri
Publisher: IOS Press
ISBN: 1586037285
Category : Computers
Languages : en
Pages : 360

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Surveys general results on multiple-access channels, and gives an overview of the problems of CDMA solutions. This work includes chapters devoted to the information-theoretical aspects of multiple-access communication. It discusses multiple-access techniques and covers coding techniques.

Author: Nazli Ahmad Khan Beigi
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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The ubiquitous wireless networks in the next generation of communication systems have motivated advanced techniques with diverse ranges of connectivity, coverage, reliability, and throughput. The massive connectivity in the context of the heterogenous networks has conveyed to different sorts of challenges including inter-cell and intra-cell originated interferences. The complications aggravate due to the sporadic nature of the traffic generated by large-scale and low-powered networks over limited spectrum resources. In this thesis, different techniques in enhancing the reliability, as well as spectral and power efficiency in the future generations of the multi-point communication networks have been investigated. Our proposed schemes are based on the coordination of the transmitters in sharing the source information followed by the joint transmission and the iterative detection. in the context of the cooperative source and channel coding. The Non-Orthogonal Multiple Access (NOMA), Coordinated Multi-Point (CoMP) transmission and the Iterative Joint Detection and Decoding (IJDD) receivers are the frameworks that we have used to validate our proposed improvements. We have initially investigated the cooperative NOMA as the physical layer network coding scheme in the downlink of wireless communication systems. It is proposed to benefit from the so-called interference received from adjacent cells instead of ignoring or cancelling them, as in the state-of-the-art systems. The application of cooperative NOMA is evaluated in a system-level information theoretic framework to optimize the user-pairing strategy. The results show the cell edges with the strongest interference are the optimal vicinity for the NOMA applications. Further, we have evaluated the NOMA for the uplink in the dense Internet of Things (IoT) systems, where the sensor elements observe the correlated sources. Realizing that the separation of source coding from channel coding in NOMA systems with correlated sources is suboptimal, we propose our scheme based on the cooperative source and channel coding. The transmitters are assumed to be privy to the whole data through a high-rate and low-latency background connection. The cooperative source coding is then followed by the transmission over the non-orthogonal multiple access (NOMA) channel. As the transmit signals experience different delay-spreads through the channel, the data streams are received asynchronously, resulting in inter-symbol interference (ISI) at the receiver. We show that the correlated nature of the asynchronous channels can be exploited as the extra source of information, provided that a proper detection technique is adopted. The capacity region is developed, where the sum-rate exceeds that of the synchronous NOMA. The potency of the successive interference cancellation (SIC) receivers, as the main block in NOMA receivers, is investigated. By applying water-filling and geometric power allocation, we show that the NOMA performance degradation in asynchronous channels is caused by the nature of SIC. We have proposed our iterative joint detection and decoding (IJDD) receiver that outperforms SIC in asynchronous NOMA receivers. Moreover, we have addressed two key challenges in Coordinated Multi-point (CoMP) networks. The asynchronous downlink and imperfect channel state information (CSI) are jointly considered in an information theoretical framework. We assume delays from the Transmission and Reception Points (TRP) to the target user, in general, may exceed cyclic prefix (CP) length, causing symbol-asynchronous reception at the receiver. We characterize an accurate mathematical model for the asynchronous Rayleigh fading channel with imperfect CSI for multi-TRP schemes. We have derived the capacity region for asynchronous CoMP systems and have generalized it to the multi-TRP schemes. We propose a low-complexity iterative detection scheme targeting minimizing the mean square error (MMSE) in our asynchronous fading channel model. Finally, we have associated the coordinated multi-point transmission with NOMA methodology. We have considered the downlink CoMP in a Single-Frequency Network (SFN) of Digital Terrestrial Television (DTT) broadcasting network. The coordinated transmit signals are assumed to have embedded Layered-Division Multiplexing (LDM) to enhance the coverage, reliability, and spectral efficiency in multi-content broadcasting. We have extended the MMSE-IJDD receiver to higher order modulation formats and have evaluated the order of the computational complexity for our proposed receiver to be in a decent range. Our extensive simulations validate the proposed scheme providing a considerable boost in the channel reliability, while enhancing the spectral and power efficiency, even as the number of TRPs increases.

Author: Gamaethige Francis Robert Sulak Soysa
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Boulos Wadih Khoueiry
Publisher:
ISBN:
Category :
Languages : en
Pages : 162

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Radio access technologies for mobile communications are characterized by multiple access (MA) strategies. Orthogonal MA techniques were a reasonable choice for achieving good performance with single user detection. With the tremendous growth in the number of mobile users and the new internet of things (IoT) shifting paradigm, it is expected that the monthly mobile data traffic worldwide will exceed 24.3 exabytes by 2019, over 100 billion IoT connections by 2025, and the financial impact of IoT on the global economy varies in the range of 3.9 to 11.1 trillion dollars by 2025. In light of the envisaged exponential growth and new trends, one promising solution to further enhance data rates without increasing the bandwidth is by increasing the spectral efficiency of the channel. Non-orthogonal MA techniques are potential candidates for future wireless communications. The two corner points on the boundary region of the MA channel are known to be achievable by single user decoding followed by successive decoding (SD). Other points can also be achieved using time sharing or rate splitting. On the other hand, machine-to-machine (M2M) communication which is an enabling technology for the IoT, enables massive multipurpose networked devices to exchange information among themselves with minor or no human intervention. This thesis consists of three main parts. In the first part, we propose new practical encoding and joint belief propagation (BP) decoding techniques for 2-user MA erasure channel (MAEC) that achieve any rate pair close to the boundary of the capacity region without using time sharing nor rate splitting. While at the encoders, the corresponding parity check matrices are randomly built from a half-rate LDPC matrix, the joint BP decoder employs the associated Tanner graphs of the parity check matrices to iteratively recover the erasures in the received combined codewords. Specifically, the joint decoder performs two steps in each decoding iteration: 1) simultaneously and independently runs the BP decoding process at each constituent sub-graph to recover some of the common erasures, 2) update the other sub-graph with newly recovered erasures and vice versa. When the number of erasures in the received combined codewords is less than or equal to the number of parity check constraints, the decoder may successfully decode both codewords, otherwise the decoder declares decoding failure. Furthermore, we calculate the probability of decoding failure and the outage capacity. Additionally, we show how the erasure probability evolves with the number of decoding iterations and the maximum tolerable loss. Simulations show that any rate pair close to the capacity boundary is achievable without using time sharing. In the second part, we propose a new cooperative joint network and rateless coding strategy for machine-type communication (MTC) devices in the multicast settings where three or more MTC devices dynamically form a cluster to disseminate messages between themselves. Specifically, in the basic cluster, three MTC devices transmit their respective messages simultaneously to the relay in the first phase. The relay broadcasts back the combined messages to all MTC devices within the basic cluster in the second phase. Given the fact that each MTC device can remove its own message, the received signal in the second phase is reduced to the combined messages coming from the other two MTC devices. Hence, this results in exploiting the interference caused by one message on the other and therefore improving the bandwidth efficiency. Furthermore, each group of three MTC devices in vicinity can form a basic cluster for exchanging messages, and the basic scheme extends to N MTC devices. Furthermore, we propose an efficient algorithm to disseminate messages among a large number of MTC devices. Moreover, we implement the proposed scheme employing practical Raptor codes with the use of two relaying schemes, namely amplify and forward (AF) and de-noise and forward (DNF). We show that with very little processing at the relay using DNF relaying scheme, performance can be further enhanced. We also show that the proposed scheme achieves a near optimal sum rate performance. In the third part, we present a comparative study of joint channel estimation and decoding of factor graph-based codes over flat fading channels and propose a simple channel approximation scheme that performs close to the optimal technique. Specifically, when channel state information (CSI) is not available at the receiver, a simpler approach is to estimate the channel state of a group of received symbols, then use the approximated value of the channel with the received signal to compute the log likelihood ratio. Simulation results show that the proposed scheme exhibits about 0.4 dB loss compared to the optimal solution when perfect CSI is available at the receiver.

Author: K.C. Raveendranathan
Publisher: CRC Press
ISBN: 1040134955
Category : Technology & Engineering
Languages : en
Pages : 315

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Book Description
The reference text discusses signal processing tools and techniques used for the design, testing, and deployment of communication systems. It further explores software simulation and modeling tools like MATLAB, GNU Octave, Mathematica, and Python for modeling, simulation, and detailed analysis leading to comprehensive insights into communication systems. The book explains topics such as source coding, pulse demodulation systems, and the principle of sampling and aliasing. This book: Discusses modern techniques including analog and digital filter design, and modulation principles including quadrature amplitude modulation, and differential phase shift keying. Covers filter design using MATLAB, system simulation using Simulink, signal processing toolbox, linear time-invariant systems, and non-linear time-variant systems. Explains important pulse keying techniques including Gaussian minimum shift keying and quadrature phase shift keying. Presents signal processing tools and techniques for communication systems design, modeling, simulation, and deployment. Illustrates topics such as software-defined radio (SDR) systems, spectrum sensing, and automated modulation sensing. The text is primarily written for senior undergraduates, graduate students, and academic researchers in the fields of electrical engineering, electronics and communication engineering, computer science, and engineering.

Author: Ezio Biglieri
Publisher: Springer Science & Business Media
ISBN: 1402080840
Category : Technology & Engineering
Languages : en
Pages : 433

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Accessible introduction to the theoretical foundations of modern coding theory Including numerous applications to wireless transmission systems The author is famous in the field of coding and wireless communications for his work in the area of faded channels & communcations.

Author: Mojtaba Vaezi
Publisher: Springer
ISBN: 3319920901
Category : Technology & Engineering
Languages : en
Pages : 692

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Book Description
This book presents comprehensive coverage of current and emerging multiple access, random access, and waveform design techniques for 5G wireless networks and beyond. A definitive reference for researchers in these fields, the book describes recent research from academia, industry, and standardization bodies. The book is an all-encompassing treatment of these areas addressing orthogonal multiple access and waveform design, non-orthogonal multiple access (NOMA) via power, code, and other domains, and orthogonal, non-orthogonal, and grant-free random access. The book builds its foundations on state of the art research papers, measurements, and experimental results from a variety of sources.