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2013 | Buch

A Modified Scheme for PAPR Reduction in OFDM System Based on Clipping Method Kapitel lesen Erstes Kapitel lesen

Multiple Access Communcations

6th International Workshop, MACOM 2013, Vilnius, Lithuania, December 16-17, 2013. Proceedings

herausgegeben von: Magnus Jonsson, Alexey Vinel, Boris Bellalta, Ninoslav Marina, Desislava Dimitrova, Dieter Fiems

Verlag: Springer International Publishing

Buchreihe : Lecture Notes in Computer Science

Enthalten in: Springer Professional "Wirtschaft+Technik" , Springer Professional "Technik" , Springer Professional "Wirtschaft"

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Über dieses Buch

This book constitutes the refereed proceedings of the 6th International Workshop on Multiple Access Communications, MACOM 2013, held in Vilnius, Lithuania, in December 2013. The 16 full papers presented were carefully reviewed and selected from various submissions. They describe the latest advancements in the field of multiple access communications with an emphasis on OFDM techniques, channel coding, spectrum management, medium access control protocols and different aspects of wireless access networks.

Inhaltsverzeichnis

Frontmatter

OFDM

A Modified Scheme for PAPR Reduction in OFDM System Based on Clipping Method
Abstract
Reducing the peak-to-average power ratio (PAPR) of Orthogonal frequency division multiplexing (OFDM) has become the most popular technology for high data rate transmission in recent years. However, most of the proposed schemes either have a high computational complexity or poor bit error rate (BER) performance. Among them, signal clipping is the simplest method to improve the OFDM system’s PAPR performance, but it results in serious degradation of the BER performance. In this paper, a modified Clipping scheme based on quantization method is proposed by quantizing the transmitted signal to a group of preset threshold. Simulation results show that the new scheme can significantly improve the BER and the out-of-band radiation performance while guaranteeing the PAPR performance of the QAM-OFDM system.
Jing Yan, Jianping Wang, Zhen He
Impulse Noise Mitigation for OFDM by Time-Frequency Spreading
Abstract
This paper deals with the impulse interferences in modern vehicles and assesses the suitability of establishing in-vehicle wireless links replacing standard data cable bundles. According to our experiments, the standard UMTS Long Term Evolution (LTE) is highly affected by impulse noise. We compare it with a novel 2D signal spreading method exploiting the orthogonal Walsh-Hadamard sequences in order to spread the transmitted signal in time and frequency. This method requires minor modification of the 3GPP LTE standard while no additional bandwidth nor noticeable computational power is required. In the presence of impulse noise, the novel 2D spreading method outperforms the standard compliant LTE significantly.
As a system model, we used an open source LTE downlink simulator developed at Vienna University of Technology and the Middleton Class A impulse noise model.
Jiri Blumenstein, Roman Marsalek, Ales Prokes, Christoph Mecklenbräuker

Channel Coding

Analog Joint Source Channel Coding for Gaussian Multiple Access Channels
Abstract
We investigate the problem of transmiting independent sources over the Gaussian Multiple Access Channel (MAC) using a CDMA-like access scheme that allows users to transmit at different rates. Rather than using standard digital communications systems, we focus on analog joint source-channel coding techniques to encode each user’s source. We analyze the performance of the proposed scheme and demonstrate its optimality. Simulation results with practical analog joint source-channel codes optimized for point-to-point communications show that the resulting performance is very close to the theoretical limits.
Mohamed Hassanin, Oscar Fresnedo, Javier Garcia-Frias, Luis Castedo
Inner Convolutional Codes and Ordered Statistics Decoding in a Multiple Access System Enabling Wireless Coexistence
Abstract
The problem of wireless coexistence will become crucial in years to come. Future generation communication systems will have to endure interference induced by communication systems operating within the same frequency bands. Coded DHA FH OFDMA using ordered statistics is well suited for the task. This paper addresses the problem of transmission rate increase in a coded DHA FH OFDMA system. It will be demonstrated that using q-ary convolutional codes constructed from punctured Reed-Solomon codes as inner codes in a coded DHA FH OFDMA provides rates sufficiently higher than those ensured by block inner codes ensuring at the same time reasonable decoding complexity, relatively small codeword length and low probability of error.
Dmitry Osipov
Delay-Doppler Space Division-Based Multiple-Access Solves Multiple-Target Detection
Abstract
Non-coherent signal with unknown delay and Doppler is recovered by Gabor Division/Spread Spectrum System (GD/S3). A transmitted signal in GD/S3 is expressed by a Gabor expansion whose expansion coefficient is a product of time domain (TD) and frequency domain (FD) spread spectrum (SS) codes. A receiver in GD/S3 employs multiple TD integrators with TD SS codes and a prescribed delay and FD integrators with FD SS codes and a prescribed Doppler. These integrators estimate and update Doppler and delay cooperatively and individually. The receiver of GD/S3 is applicable to a multiple-target problem by borrowing an idea from code division multiple access (CDMA) philosophy. Namely, a delay-Doppler space is partitioned into four sub-spaces and their associated two-dimensional (2D) SS codes are assigned. Four delay-Doppler targets can be resolved and detected by four pairs of TD and FD correlators using the assigned SS codes.
Yutaka Jitsumatsu, Tohru Kohda, Kazuyuki Aihara

Medium Access Control Protocols

A Real-Time Medium Access Protocol Supporting Dynamic Spectrum Allocation in Industrial Networks
Abstract
Cognitive radio with spectrum sensing and spectrum reuse has great opportunities for industrial networking. Adapting to the current interference situation and utilising the available frequencies in an effective manner can greatly improve the data delivery capabilities. At the same time, real-time demands must be met. In this paper, we present a medium access control protocol supporting dynamic spectrum allocation as done in cognitive radio networks, providing deterministic medium access for heterogeneous traffic. The possibility of spectrum sensing in the nodes opens up for the possibility of increasing successful data transmissions, and a real-time analysis framework with three formalized constraints to be tested provides support for guaranteed timely treatment of hard real-time traffic. The real-time analysis framework includes a new type of delay check that more exactly bounds the delay compared to earlier work. Simulation experiments and performance comparisons are provided.
Magnus Jonsson, Kristina Kunert, Urban Bilstrup
CSMA/CA Bottleneck Remediation in Saturation Mode with New Backoff Strategy
Abstract
Many modern wireless networks integrate carrier sense multiple access/collision avoidance (CSMA/CA) with exponential backoff as medium access control (MAC) technique. In order to decrease the MAC overhead and the collision probability, we propose in this paper a new backoff strategy leading to better saturation throughput and access delay performance comparing to the classical protocol. We investigate the CSMA/CA with RTS/CTS technique, and we show that our strategy reaches better saturation throughput and access delay especially in dense networks. This proposed strategy distributes users over all the backoff stages to solve the bottleneck problem present in the first backoff stage. Finally, we analyze our strategy and we compare it to the classical one modeled by Markov chain. Analytical and simulation results show the improvment in term of saturation throughput. Cumulative density function (CDF) of the access delay illustrates the important gain obtained by the proposed strategy.
Baher Mawlawi, Jean-Baptiste Doré
Prototyping Distributed Collision-Free MAC Protocols for WLANs in Real Hardware
Abstract
Carrier Sense Multiple Access with Enhanced Collision Avoidance (CSMA/ECA) is a totally distributed, collision-free MAC protocol for IEEE 802.11 WLANs. It is capable of achieving greater throughput than the MAC protocol used in the current standard, called Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA), by means of picking a deterministic backoff after successful transmissions. This work is the first implementation of the main concept behind CSMA/ECA on real hardware. Experimental results confirm the advantages of CSMA/ECA over CSMA/CA in terms of throughput and set the ground for its complete prototyping on real hardware using OpenFWWF.
Luis Sanabria-Russo, Jaume Barcelo, Boris Bellalta
Performance Analysis of Cooperative Cognitive Distributed MAC Protocol with Full Duplex Links
Abstract
Recent advancements in Full Duplex (FD) wireless system opens up many research opportunities in the Medium Access Control (MAC) layer. In this paper, we propose Cooperative Cognitive Distributed MAC (CCD-MAC) protocol in which the FD Secondary User (SU) will help Primary User (PU) by relaying PU’s packet when the primary link quality is bad. We consider two-state primary link quality model with fixed Average Non-Fade Duration for ‘Good’ state followed by exponentially distributed fading duration for ‘Bad’ state. When the PU is idle, SUs use p-persistent CSMA protocol for channel access. An analytical model has been developed for the proposed protocol. Using our model, throughput of secondary network and the delay experienced by PU’s packet are calculated. The validity of the analytical work is supported with simulation results.
Senthilmurugan S., T. G. Venkatesh

Wireless Networks

Large-Scale Femtocell Network Deployment and Measurements
Abstract
Modern, advanced mobile radio networks have billions of users and an increasing amount is using the mobile networks indoors. Smartphones are designed for data consumption and thus the demand is for higher and higher throughput rates. At the same time the users and operators of mobile radio networks encounter difficulties with coverage gaps, especially indoors. Femtocells are a new concept that aims for ease of use, low cost and high performance in providing coverage and capacity for indoor users. This paper presents measurement results for an arbitrary, large-scale, indoor femtocell deployment. The measurements revealed clear promise in the technology, but at the same time difficulties with interference in such a high density femtocell environment. Power management is increasingly important in femtocell deployments as the placement is uncontrolled by the operator. Femtocell network parameters and density have a clear impact on the performance.
Miika Kankare, Ari Asp, Yaroslav Sydorov, Jarno Niemelä, Mikko Valkama
Empirical Study on Local Similarity of Spectrum Occupancy in the 2.4 GHz ISM Band
Abstract
The 2.4 GHz frequency band is used by various devices, including WiFi, microwave ovens and Bluetooth. For WiFi devices, it is desirable to have information about occupancy of the spectrum available to select optimal channels and to predict link performance. As only few devices are capable of acquiring such information, devices may share it. However, using these information only makes sense if the measurements are made by a device that is nearby. In this paper, we suggest using information about present WiFi devices to assess proximity. We present the design and results of an extensive indoor study carried out to assess locality of spectrum occupancy and usefulness of the described nearness measure.
Till Wollenberg, Andreas Dähn
Analyzing Coexistence Issues in Wireless Radio Networks: Simulation of Bluetooth Interfered by Multiple WLANs
Abstract
In many fields of technology more mobile transmission paths will be used in the future. In order to ensure a secure transmission of data, studies for coexistence of the used radio technologies with other currently wide used radio systems (WLAN, Bluetooth, ZigBee, etc.), are needed. Since an analytical treatment is too complex and a real test set is usually too expensive, the objective is the construction of a suitable simulation environment to investigate the performance of co-existing wireless systems in an economical way. Investigations of a variety of representative application scenarios indicated, that a universal applicability and adaptability of such a simulation framework can be achieved by a high-grade modular design. To keep the simulation results as realistic as possible, the use of statistical radio channel data was largely omitted. Instead, an accurate recording of the simulated scenario is done to compute the required channel characteristics by ray-tracing/-launching algorithms. The signal processing chains of the transmitters and receivers (user- and jammer-radio) were reproduced precisely to their specifications and for easy interchangeability they are connected to the channel via a universal defined interface. Finally an application scenario (Bluetooth connection interfered by multiple WLAN transmitters) is presented and the results of the simulations are shown and discussed.
Roland Neumeier, Gerald Ostermayer
Capacity Analysis of IEEE 802.11ah WLANs for M2M Communications
Abstract
Focusing on the increasing market of the sensors and actuators networks, the IEEE 802.11ah Task Group is currently working on the standardization of a new amendment. This new amendment will operate at the sub-1GHz band, ensure transmission ranges up to 1 Km, data rates above 100 kbps and very low power operation. With IEEE 802.11ah, the WLANs will offer a solution for applications such as smart metering, plan automation, eHealth or surveillance. Moreover, thanks to a hierarchical signalling, the IEEE 802.11ah will be able to manage a higher number of stations (STAs) and improve the 802.11 Power Saving Mechanisms. In order to support a high number of STAs, two different signalling modes are proposed, TIM and Non-TIM Offset. In this paper we present a theoretical model to predict the maximum number of STAs supported by both modes depending on the traffic load and the data rate used. Moreover, the IEEE 802.11ah performance and energy consumption for both signalling modes and for different traffic patterns and data rates is evaluated. Results show that both modes achieve similar Packet Delivery Ratio values but the energy consumed with the TIM Offset is, in average, 11.7% lower.
T. Adame, A. Bel, B. Bellalta, J. Barcelo, J. Gonzalez, M. Oliver

Information Theory

Braess-Type Paradox in Self-optimizing Wireless Networks
Abstract
The Braess’s paradox, also called Braess paradox, in transportation networks states that adding extra capacity to a network, when moving entities with incomplete information selfishly choose their routes, can in some cases reduce the overall network performance. In this paper, we observe a similar phenomenon in wireless networks. More specifically, we consider a single-cell system with two different types of access points, one of them with a fixed rate and one of them with a variable rate, i.e., a rate that depends on the number of users connected to that access point. We observe that, under certain conditions, the intersystem connection between these two types of access points does not necessarily improve the overall system performance. In other words, after the interconnection, the individual rates of users as well as their sum rate might get worse. This is similar to the original Braess paradox where adding a new route does not necessarily improve the overall traffic throughput. We develop a general model that describes under which conditions and for which families of variable rate functions this paradox happens. abstract environment.
Ninoslav Marina
Stationary Equilibrium Strategies for Bandwidth Scanning
Abstract
In this paper we investigate the problem of designing a spectrum multi-step scanning strategy to detect an intelligent Invader who wants to utilize spectrum undetected for his/her unapproved purposes. To deal with this problem, we model it as a two stage game, along with specifying an algorithm of scanning the spectrum and evaluating the stationary bandwidth of spectrum to scan. The game is solved explicitly and reveal interesting properties. In particular, we have found a discontinuous dependence of the equilibrium strategies on the network parameters, fine and the Invader’s intention for illegal activity, which can lead even to multi-equilibrium situation. To select a proper equilibrium strategy the best response strategy algorithm can be applied which in the multi-equilibria case always converges for a finite number of iteration, meanwhile for mono-equilibria situation it does not converge, circling around the equilibrium. Also, we have shown that the detection probability and payoffs in some situation can be very sensible to fine and the Invader’s intention to intrude into the network longer, what yields that the network provider has to carefully make a value judgement of fine and estimation of the Intruder’s intentions.
Andrey Garnaev, Wade Trappe
Backmatter
Metadaten
Titel
Multiple Access Communcations
herausgegeben von
Magnus Jonsson
Alexey Vinel
Boris Bellalta
Ninoslav Marina
Desislava Dimitrova
Dieter Fiems
Copyright-Jahr
2013
Verlag
Springer International Publishing
Electronic ISBN
978-3-319-03871-1
Print ISBN
978-3-319-03870-4
DOI
https://doi.org/10.1007/978-3-319-03871-1

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