Distributed cooperative data transfer for UWB adhoc network

Published versio

Spectral efficiency optimization with distributed beamforming in UWB based implant body area networks

Copyright © 2014 ICST. In this paper, a distributed beamforming problem is investigated based on spectral efficiency (SE) optimization for ultra-wideband (UWB) based implant body area networks (IBANs). We consider a relay network consisting of one implant source, several wearable relays, and one body network coordinator under the assumption that the individual relay power is constrained due to the Federal Communications Commission (FCC) regulations for UWB signals. Taking into account realistic wireless channels and relay locations, the SE optimization problem is mathematically formulated and solved by using convex optimization. Simulation results show that the proposed beamforming scheme is superior to other transmission schemes. Moreover, our numerical examples reveal that the relay location has a significant impact on the beamforming performance and the proposed beamforming scheme provides an efficient way to prolong the lifetime of the implant node

Cooperative communications in wireless networks : novel approaches in the mac layer

Master'sMASTER OF ENGINEERIN

Cooperative Wireless Systems

This Ph.D. dissertation reports on the work performed at the Wireless Communication Laboratory - University of Bologna and National Research Council - as well as, for six months, at the Fraunhofer Institute for Integrated Circuit (IIS) in Nürnberg. The work of this thesis is in the area of wireless communications, especially with regards to cooperative communications aspects in narrow-band and ultra-wideband systems, cooperative links characterization, network geometry, power allocation techniques,and synchronization between nodes. The underpinning of this work is devoted to developing a general framework for design and analysis of wireless cooperative communication systems, which depends on propagation environment, transmission technique, diversity method, power allocation for various scenarios and relay positions. The optimal power allocation for minimizing the bit error probability at the destination is derived. In addition, a syncronization algorithm for master-slave communications is proposed with the aim of jointly compensate the clock drift and offset of wireless nodes composing the network

Self-concatenated coding for wireless communication systems

In this thesis, we have explored self-concatenated coding schemes that are designed for transmission over Additive White Gaussian Noise (AWGN) and uncorrelated Rayleigh fading channels. We designed both the symbol-based Self-ConcatenatedCodes considered using Trellis Coded Modulation (SECTCM) and bit-based Self- Concatenated Convolutional Codes (SECCC) using a Recursive Systematic Convolutional (RSC) encoder as constituent codes, respectively. The design of these codes was carried out with the aid of Extrinsic Information Transfer (EXIT) charts. The EXIT chart based design has been found an efficient tool in finding the decoding convergence threshold of the constituent codes. Additionally, in order to recover the information loss imposed by employing binary rather than non-binary schemes, a soft decision demapper was introduced in order to exchange extrinsic information withthe SECCC decoder. To analyse this information exchange 3D-EXIT chart analysis was invoked for visualizing the extrinsic information exchange between the proposed Iteratively Decoding aided SECCC and soft-decision demapper (SECCC-ID). Some of the proposed SECTCM, SECCC and SECCC-ID schemes perform within about 1 dB from the AWGN and Rayleigh fading channels’ capacity. A union bound analysis of SECCC codes was carried out to find the corresponding Bit Error Ratio (BER) floors. The union bound of SECCCs was derived for communications over both AWGN and uncorrelated Rayleigh fading channels, based on a novel interleaver concept.Application of SECCCs in both UltraWideBand (UWB) and state-of-the-art video-telephone schemes demonstrated its practical benefits.In order to further exploit the benefits of the low complexity design offered by SECCCs we explored their application in a distributed coding scheme designed for cooperative communications, where iterative detection is employed by exchanging extrinsic information between the decoders of SECCC and RSC at the destination. In the first transmission period of cooperation, the relay receives the potentially erroneous data and attempts to recover the information. The recovered information is then re-encoded at the relay using an RSC encoder. In the second transmission period this information is then retransmitted to the destination. The resultant symbols transmitted from the source and relay nodes can be viewed as the coded symbols of a three-component parallel-concatenated encoder. At the destination a Distributed Binary Self-Concatenated Coding scheme using Iterative Decoding (DSECCC-ID) was employed, where the two decoders (SECCC and RSC) exchange their extrinsic information. It was shown that the DSECCC-ID is a low-complexity scheme, yet capable of approaching the Discrete-input Continuous-output Memoryless Channels’s (DCMC) capacity.Finally, we considered coding schemes designed for two nodes communicating with each other with the aid of a relay node, where the relay receives information from the two nodes in the first transmission period. At the relay node we combine a powerful Superposition Coding (SPC) scheme with SECCC. It is assumed that decoding errors may be encountered at the relay node. The relay node then broadcasts this information in the second transmission period after re-encoding it, again, using a SECCC encoder. At the destination, the amalgamated block of Successive Interference Cancellation (SIC) scheme combined with SECCC then detects and decodes the signal either with or without the aid of a priori information. Our simulation results demonstrate that the proposed scheme is capable of reliably operating at a low BER for transmission over both AWGN and uncorrelated Rayleigh fading channels. We compare the proposed scheme’s performance to a direct transmission link between the two sources having the same throughput

Cooperative routing in wireless ad hoc networks.

Cheung, Man Hon.Thesis (M.Phil.)--Chinese University of Hong Kong, 2007.Includes bibliographical references (leaves 89-94).Abstracts in English and Chinese.Abstract --- p.iAcknowledgement --- p.iiiChapter 1 --- Introduction --- p.1Chapter 1.1 --- Rayleigh Fading Channels --- p.1Chapter 1.2 --- Ultra-Wideband (UWB) Communications --- p.2Chapter 1.2.1 --- Definition --- p.2Chapter 1.2.2 --- Characteristics --- p.3Chapter 1.2.3 --- UWB Signals --- p.4Chapter 1.2.4 --- Applications --- p.5Chapter 1.3 --- Cooperative Communications --- p.7Chapter 1.4 --- Outline of Thesis --- p.7Chapter 2 --- Background Study --- p.9Chapter 2.1 --- Interference-Aware Routing --- p.9Chapter 2.2 --- Routing in UWB Wireless Networks --- p.11Chapter 2.3 --- Cooperative Communications and Routing --- p.12Chapter 3 --- Cooperative Routing in Rayleigh Fading Channel --- p.15Chapter 3.1 --- System Model --- p.16Chapter 3.1.1 --- Transmitted Signal --- p.16Chapter 3.1.2 --- Received Signal and Maximal-Ratio Combining (MRC) --- p.16Chapter 3.1.3 --- Probability of Outage --- p.18Chapter 3.2 --- Cooperation Criteria and Power Distribution --- p.21Chapter 3.2.1 --- Optimal Power Distribution Ratio --- p.21Chapter 3.2.2 --- Near-Optimal Power Distribution Ratio β´ة --- p.21Chapter 3.2.3 --- Cooperation or Not? --- p.23Chapter 3.3 --- Performance Analysis and Evaluation --- p.26Chapter 3.3.1 --- 1D Poisson Random Network --- p.26Chapter 3.3.2 --- 2D Grid Network --- p.28Chapter 3.4 --- Cooperative Routing Algorithm --- p.32Chapter 3.4.1 --- Cooperative Routing Algorithm --- p.33Chapter 3.4.2 --- 2D Random Network --- p.35Chapter 4 --- UWB System Model and BER Expression --- p.37Chapter 4.1 --- Transmit Signal --- p.37Chapter 4.2 --- Channel Model --- p.39Chapter 4.3 --- Received Signal --- p.39Chapter 4.4 --- Rake Receiver with Maximal-Ratio Combining (MRC) --- p.41Chapter 4.5 --- BER in the presence of AWGN & MUI --- p.46Chapter 4.6 --- Rake Receivers --- p.47Chapter 4.7 --- Comparison of Simple Routing Algorithms in ID Network --- p.49Chapter 5 --- Interference-Aware Routing in UWB Wireless Networks --- p.57Chapter 5.1 --- Problem Formulation --- p.57Chapter 5.2 --- Optimal Interference-Aware Routing --- p.58Chapter 5.2.1 --- Link Cost --- p.58Chapter 5.2.2 --- Per-Hop BER Requirement and Scaling Effect --- p.59Chapter 5.2.3 --- Optimal Interference-Aware Routing --- p.61Chapter 5.3 --- Performance Evaluation --- p.64Chapter 6 --- Cooperative Routing in UWB Wireless Networks --- p.69Chapter 6.1 --- Two-Node Cooperative Communication --- p.69Chapter 6.1.1 --- Received Signal for Non-Cooperative Communication --- p.69Chapter 6.1.2 --- Received Signal for Two-Node Cooperative Communication --- p.70Chapter 6.1.3 --- Probability of Error --- p.71Chapter 6.2 --- Problem Formulation --- p.75Chapter 6.3 --- Cooperative Routing Algorithm --- p.77Chapter 6.4 --- Performance Evaluation --- p.80Chapter 7 --- Conclusion and Future Work --- p.85Chapter 7.1 --- Conclusion --- p.85Chapter 7.2 --- Future Work --- p.86Chapter 7.2.1 --- Distributed Algorithm --- p.87Chapter 7.2.2 --- Performance Analysis in Random Networks --- p.87Chapter 7.2.3 --- Cross-Layer Optimization --- p.87Chapter 7.2.4 --- Game Theory --- p.87Chapter 7.2.5 --- Other Variations in Cooperative Schemes --- p.88Bibliography --- p.8

Relaying Techniques for Multi Hop Differential Transmitted Reference IR-UWB Systems

This thesis develops novel relaying techniques to overcome the limited coverage of Impulse Radio Ultra Wideband (IR-UWB) systems based on Differential Transmitted Reference (DTR). Firstly, we describe a cooperative approach for two hop Amplify-and-Forward (A&F) relaying that exploits both the signal forwarded by the relay and the one directly transmitted by the source. After deriving the log-likelihood ratio based decision rule, we propose a semi-analytical power allocation strategy by evaluating a closed form expression for the effective Signal to Noise Ratio (SNR) at the destination, which is maximized by exhaustive search. Successively, we present a Joint Power Allocation and Path Selection (JPAPS) method for multi hop Decode-and-Forward (D&F) relaying. Starting from the heuristic consideration that the overall Bit Error Rate (BER) of the system is essentially driven by the quality of the path with the best performance, the proposed technique associates to each possible route a metric given by an approximation of the minimum BER which can be achieved as the power allocation coefficients vary and then takes into account only the path minimizing that metric. Specifically, we employ an equal SNR power allocation strategy that yields a closed form expression for the power allocation coefficients and we describe a path selection algorithm with polynomial complexity. Simulation results show the remarkable SNR gains obtained by the proposed schemes with respect to direct transmission and existing relaying techniques. Lo scopo di questa tesi è elaborare nuove tecniche di relaying per risolvere il problema della copertura limitata in sistemi radio ad impulsi a banda ultra larga (Impulse-Radio Ultra-Wideband, IR-UWB) basati su Differential Transmitted Reference (DTR). Innanzi tutto, si descrive un approccio cooperativo per singolo relay Amplify-and-Forward (A&F) che sfrutta sia il segnale inoltrato dal relay sia quello trasmesso direttamente dalla sorgente. Dopo aver introdotto una regola di decisione basata sul logaritmo del rapporto di verosimiglianza, si propone una strategia di allocazione di potenza semi-analitica valutando un'espressione in forma chiusa per il rapporto segnale rumore (SNR) effettivo al nodo destinazione, che viene massimizzato per mezzo di una ricerca esaustiva. Successivamente, si presenta un metodo congiunto di allocazione di potenza e scelta del cammino ottimo (Joint Power Allocation and Path Selection, JPAPS) per relay Decode-and-Forward (D&F) multipli. Partendo dalla considerazione euristica che la probabilità d'errore complessiva del sistema dipende essenzialmente dalla qualità del cammino migliore, la tecnica proposta associa ad ogni possibile percorso una metrica data da un'approssimazione della minima probabilità d'errore ottenibile al variare dei coefficienti di allocazione di potenza e poi prende in considerazione soltanto il cammino che minimizza tale metrica. Specificatamente, si adopera una strategia di allocazione di potenza in cui si impone l'uguaglianza degli SNR dei singoli link (equal SNR power allocation strategy), ottenendo un'espressione in forma chiusa per i coefficienti di allocazione di potenza. Inoltre, si descrive un algoritmo di scelta del cammino ottimo con complessità polinomiale. I risultati delle simulazioni mostrano i notevoli guadagni in termini di SNR ottenuti dagli schemi proposti rispetto alla trasmissione diretta e alle altre tecniche di relaying esistenti

Efficient approaches to robust and cooperative wireless network design

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 181-200).In wireless networks, relaying and user cooperation offer several attractive benefits such as higher throughput, better power efficiency, and larger coverage. As a result, cooperative networks are regarded as one of the most promising enabling technologies able to meet the increasingly high rate demands and quality of service requirements in wireless networks. In this dissertation, we investigate the efficient design of cooperative wireless networks from the perspectives of robust resource allocation, wideband communications, and energy efficiency. Given that the primary resource to be allocated is the relay node's transmission power, we propose robust and efficient relay power allocation algorithms when the global channel state information is subject to uncertainty. In addition, we propose practical algorithms that do not require frequent tracking of the global channel state information. This work reveals that ignoring global channel state information uncertainties and solving the relay power optimization problems often lead to poor performance, highlighting the importance of robust algorithm designs in practical wireless networks. Wideband cooperative networks allow for both higher data rate and higher resistance to interference. Since the gains achieved by using cooperation come at the cost of higher node complexity and substantial coordination overhead, it is important to study practical low-complexity signaling and receiver schemes suitable for wideband networks. In particular, we consider transmitted-reference signaling schemes and provide a unified performance analysis in terms of bit error rate. Since wideband networks are expected to coexist with many existing narrowband systems, it is important to characterize the effect of narrowband interference. We further extend the performance analysis of transmitted-reference signaling schemes to include the effect of narrowband interference..(cont) Finally, we conclude by studying the benefits of cooperation in a wireless sensor network, which aims at detecting the presence or absence of a certain physical phenomenon of interest using geographically dispersed sensor nodes. We propose a consensus flooding protocol and analyze its average energy consumption. We investigate the tradeoff between the detection reliability and the energy efficiency when nodes are allowed to cooperate. By addressing the above design challenges, this dissertation will be useful for obtaining insight into the theory and application of cooperative networks in future communication systemsby Tony Q.S. Quek.Ph.D