This document discusses the implementation of an OFDM kernel for WiMAX systems. It begins with an introduction to OFDM and how it is used in WiMAX networks. It then provides an overview of the key components in the WiMAX physical layer, including bit-level processing, OFDMA symbol-level processing, and digital intermediate frequency processing blocks. It specifically focuses on the OFDM kernel, which includes the inverse fast Fourier transform, cyclic prefix insertion, fast Fourier transform, and cyclic prefix removal blocks. Finally, it discusses how FPGAs are well-suited for implementing OFDM kernels due to their high speed complex multiplication capabilities.
The document analyzes the performance of LDPC coded WLAN physical layer under BPSK and 16-QAM modulation. It finds that an LDPC encoded WLAN system with a code rate of (48,46) performs best under BPSK modulation in an AWGN channel, achieving the lowest bit error rate. Simulation results show LDPC coding improves performance by reducing bit error rates compared to without coding. The best performing configuration provides power efficiency through lower transmitted power requirements for a given bit error rate.
This document discusses improving the bit error rate of OFDM transmission using turbo codes. It provides an overview of OFDM and its benefits, including its ability to combat multipath interference. However, OFDM results in burst errors that can degrade coding efficiency. The document proposes using turbo codes with OFDM since turbo codes can achieve performance close to the Shannon limit. It reviews the basic principles of turbo code design and encoding/decoding. The rest of the document outlines simulations done to test the performance of a turbo code combined with OFDM over AWGN and impulsive noise channels.
This document describes the design and implementation of a wideband digital down converter (DDC) on an FPGA. It discusses the theoretical blocks of a DDC including a numerically controlled oscillator (NCO), mixer, cascaded integrate-comb (CIC) filter, compensation FIR filter, and programmable FIR filter. It also describes implementing each block using advanced methods and testing the design on an FPGA using Xilinx software and a Chip Scope Pro Analyzer tool. Simulation results showing the output at each DDC block are presented.
This document summarizes issues related to medium access control (MAC) protocols for wireless ad hoc networks. It discusses common MAC protocols like ALOHA, Slotted ALOHA, CSMA, and their variants. It also covers protocols specific to wireless networks like MACA, MACAW, and CSMA/CA. Additional topics covered include Bluetooth, wireless mesh networks, mobile ad hoc networks, and wireless sensor networks. Simulation tools for modeling wireless ad hoc networks are also mentioned.
Generation and Implementation of Barker and Nested Binary codesIOSR Journals
This document discusses the generation and implementation of Barker and nested binary codes for use in radar applications. It begins with background on Barker codes and nested binary codes, which are types of phase coded waveforms used for pulse compression. Barker codes have the optimal autocorrelation sidelobe properties but are limited in length. Nested binary codes are formed by taking the Kronecker product of two Barker codes, which allows the generation of longer codes while maintaining good autocorrelation. The document then presents the methodology for implementing Barker and nested binary codes using linear feedback shift registers (LFSRs). Finally, it discusses measures for comparing signal performance such as merit factor and proposes an efficient VLSI architecture using LFSRs to generate these codes for implementation
LTE in a Nutshell: Protocol ArchitectureFrank Rayal
The document provides an overview of the protocol stack for LTE, including the control plane and user plane architectures. In the control plane, the Radio Resource Control layer handles radio-specific functionality like system information broadcasting and connection control. In the user plane, the Packet Data Convergence Protocol layer performs header compression, the Radio Link Control layer handles segmentation/concatenation and retransmission, and the Medium Access Control layer includes scheduling and hybrid ARQ.
This document discusses enhancements to the physical layer of LTE-Advanced (3GPP Release 10). It describes the downlink and uplink physical layer designs, including orthogonal multiple access schemes, reference signals, control signaling, and data transmission methods. It also covers support for time division duplexing, half-duplex frequency division duplexing, and UE categories defined in 3GPP Release 8. The goal of LTE-Advanced is to further improve the LTE standard to meet the requirements of IMT-Advanced.
The document analyzes the performance of LDPC coded WLAN physical layer under BPSK and 16-QAM modulation. It finds that an LDPC encoded WLAN system with a code rate of (48,46) performs best under BPSK modulation in an AWGN channel, achieving the lowest bit error rate. Simulation results show LDPC coding improves performance by reducing bit error rates compared to without coding. The best performing configuration provides power efficiency through lower transmitted power requirements for a given bit error rate.
This document discusses improving the bit error rate of OFDM transmission using turbo codes. It provides an overview of OFDM and its benefits, including its ability to combat multipath interference. However, OFDM results in burst errors that can degrade coding efficiency. The document proposes using turbo codes with OFDM since turbo codes can achieve performance close to the Shannon limit. It reviews the basic principles of turbo code design and encoding/decoding. The rest of the document outlines simulations done to test the performance of a turbo code combined with OFDM over AWGN and impulsive noise channels.
This document describes the design and implementation of a wideband digital down converter (DDC) on an FPGA. It discusses the theoretical blocks of a DDC including a numerically controlled oscillator (NCO), mixer, cascaded integrate-comb (CIC) filter, compensation FIR filter, and programmable FIR filter. It also describes implementing each block using advanced methods and testing the design on an FPGA using Xilinx software and a Chip Scope Pro Analyzer tool. Simulation results showing the output at each DDC block are presented.
This document summarizes issues related to medium access control (MAC) protocols for wireless ad hoc networks. It discusses common MAC protocols like ALOHA, Slotted ALOHA, CSMA, and their variants. It also covers protocols specific to wireless networks like MACA, MACAW, and CSMA/CA. Additional topics covered include Bluetooth, wireless mesh networks, mobile ad hoc networks, and wireless sensor networks. Simulation tools for modeling wireless ad hoc networks are also mentioned.
Generation and Implementation of Barker and Nested Binary codesIOSR Journals
This document discusses the generation and implementation of Barker and nested binary codes for use in radar applications. It begins with background on Barker codes and nested binary codes, which are types of phase coded waveforms used for pulse compression. Barker codes have the optimal autocorrelation sidelobe properties but are limited in length. Nested binary codes are formed by taking the Kronecker product of two Barker codes, which allows the generation of longer codes while maintaining good autocorrelation. The document then presents the methodology for implementing Barker and nested binary codes using linear feedback shift registers (LFSRs). Finally, it discusses measures for comparing signal performance such as merit factor and proposes an efficient VLSI architecture using LFSRs to generate these codes for implementation
LTE in a Nutshell: Protocol ArchitectureFrank Rayal
The document provides an overview of the protocol stack for LTE, including the control plane and user plane architectures. In the control plane, the Radio Resource Control layer handles radio-specific functionality like system information broadcasting and connection control. In the user plane, the Packet Data Convergence Protocol layer performs header compression, the Radio Link Control layer handles segmentation/concatenation and retransmission, and the Medium Access Control layer includes scheduling and hybrid ARQ.
This document discusses enhancements to the physical layer of LTE-Advanced (3GPP Release 10). It describes the downlink and uplink physical layer designs, including orthogonal multiple access schemes, reference signals, control signaling, and data transmission methods. It also covers support for time division duplexing, half-duplex frequency division duplexing, and UE categories defined in 3GPP Release 8. The goal of LTE-Advanced is to further improve the LTE standard to meet the requirements of IMT-Advanced.
The document describes the V5 protocol, which is an open standard digital interface for integrated access between telecommunications networks and switches. It summarizes the key features and limitations of previous V1-V4 interfaces and introduces the V5 interface, which supports more flexible integrated access and dynamic time slot allocation. The V5 protocol consists of physical, data link, and application layers that allow signaling and transmission of voice calls over the digital interface using both communication and signaling channels. Call setup and release procedures using the V5 interface for PSTN services are also outlined.
AMD's new Bobcat core architecture is a low power x86 core designed for small die area and optimized for cloud clients. It features dual x86 decoders, out-of-order execution, 32KB L1 caches, a 512KB L2 cache, and advanced power reduction techniques to target sub-one watt operation. The goal of Bobcat is to provide 90% of the performance of mainstream notebook CPUs while using half the die area.
H.120 was the first digital video coding standard developed in 1984. H.261 in the late 1980s was the first widespread success and established the modern structure for video compression that is still used today. MPEG-1 and MPEG-2/H.262 built upon H.261 with improvements like bidirectional prediction and half-pixel motion compensation. H.263 further enhanced compression performance and is now dominant for videoconferencing, adding features such as overlapped block motion compensation.
The document summarizes research on using Run Length Encoding (RLE) to reduce Peak-to-Average Power Ratio (PAPR) in Orthogonal Frequency Division Multiplexing (OFDM) systems. Simulation results showed that RLE reduced PAPR by about 3 dB at a probability of 10-2 while maintaining a compression ratio of 1.7. The symbol error rate performance in additive white Gaussian noise and Rayleigh fading channels was unchanged with RLE. Thus, RLE is an effective PAPR reduction technique that does not degrade system performance.
This document provides information on SAF Tehnika's point-to-point microwave radio equipment for data and voice communication. It discusses their main product lines, which include the CFIP series for 1.4 GHz and license-free 24 GHz spectrum, offering capacities up to 720 Mbps. The CFIP series includes the CFIP-108 FODU for Fast Ethernet and the CFIP Lumina FODU for Gigabit Ethernet. It also discusses their CFIP PhoeniX split mount system for hybrid TDM/IP networks with capacities up to 366 Mbps. The document provides detailed specifications for these products.
The document summarizes a project report on comparing the MPEG-2 and H.264 video coding standards, with a focus on their main profiles. It finds that while MPEG-2 is widely used in digital broadcasting and DVD applications, H.264 provides better compression performance. However, MPEG-2 and H.264 are incompatible, but this can be addressed through transcoding. The report discusses the MPEG-2 and H.264 standards in detail and compares their encoding schemes, profiles and levels before analyzing different transcoding methods.
Pacific Quay has a core network with separately routed domains for users, television playout, radio production, post production, and a digital library. The fully converged network uses common hardware and protects core broadcast functions. It has a high bandwidth 40Gbps core with edge access switches connecting 22 hub rooms. Integration of different file formats, codecs, audio formats, metadata, and protocols between real-time and non-real-time systems presents challenges that require mapping schemas and determining if coupling is direct or loose. Questions can be directed to Brendan Mallon.
1. The document discusses different types of networking devices like repeaters, bridges, routers, and gateways and how they operate at different layers of the OSI model.
2. It provides examples of how these devices like repeaters, bridges, and routers are used to connect different local area networks and extends the physical length and coverage of a network.
3. The document also discusses concepts like routing tables, link state routing, and the Dijkstra algorithm that are used to determine the best paths between nodes in a network.
The document provides an overview of SONET (Synchronous Optical Network) standards:
1) SONET was developed to address the lack of interoperability between proprietary fiber optic transmission equipment from different manufacturers.
2) SONET defines optical carrier interfaces and rates to allow transmission of lower-rate signals at a common synchronous rate. This allows equipment from multiple vendors to interconnect.
3) SONET uses a layered approach, with section, line, and path overhead to monitor performance and isolate faults between network elements.
This document summarizes Laurent Leyssenne's thesis on the design of reconfigurable radiofrequency power amplifiers for wireless applications. The thesis aims to develop novel adaptive power amplifier architectures using silicon to improve battery life. It explores two families of adaptive mechanisms: discretized power amplifiers and adaptive bias power amplifiers. For discretized power amplifiers, it investigates architectures based on power stage bypass and parallel switched power cells to allow fast reconfiguration over a wide power range with low distortion. The switched power cell approach digitizes the envelope signal and uses control bits to dynamically modulate Volterra kernels, with quantization noise requiring oversampling and resolution techniques.
1) The document describes the FPGA implementation of a digital upconverter (DUC) and digital downconverter (DDC) for a WCDMA system.
2) The DUC converts a baseband signal to an intermediate frequency signal by upsampling and mixing with a carrier frequency. The DDC performs the opposite conversion from an intermediate frequency to baseband.
3) Both circuits were designed using Xilinx System Generator and implemented on a Virtex-4 FPGA. Experimental results verified the functionality of the DUC and DDC for WCDMA signal processing.
This document summarizes the porting and optimization of the ITU-T G.729.1 speech coding algorithm to the SC3850 DSP core. The authors modified the reference G.729.1 code to fix-point C and optimized it for the SC3850 architecture through techniques like replacing functions with intrinsics, inlining small functions, and restructuring loops and memory accesses. They achieved over 90% improvement in cycles per second (MCPS) through these optimizations while maintaining bit-exact accuracy against the ITU test vectors. The G.729.1 codec is an 8-32 kbps scalable wideband speech codec standardized by ITU, useful for applications like VoIP, audio conferencing, and
1) The document discusses techniques for envelope tracking power amplifiers, including reconfigurable depth adaptive biasing, to improve linearity and efficiency.
2) Reconfigurable depth adaptive biasing modifies the current consumption of the power amplifier based on the envelope signal using a controllable gain parameter.
3) This allows balancing nonlinear distortion effects to improve linearity, with the potential for degradation if the injected envelope exceeds a threshold. Memory effects must also be considered.
The document describes an 8-bit pipelined analog-to-digital converter (ADC) with a selectable resolution of 5-8 bits. The ADC was fabricated in a 0.13-micron CMOS process and achieves an effective number of bits of 6.10 in 8-bit mode with a 162 MHz input signal. Key aspects of the ADC include double sampling to relax amplifier settling times, redundant sign digit correction to compensate comparator offsets, and a two-stage op-amp design to provide sufficient gain and signal headroom given the low 1.2V supply voltage. Measured performance meets the requirements for medium resolution and sampling rate ADCs in modern synthetic aperture radar systems.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Presentation from SIEPON Seminar on 20 April in Czech Republic, sponsored by IEEE-SA & CAG. Opinions presented by the speakers in this presentation are their own, and not necessarily those of their employers or of IEEE.
Este documento presenta una introducción a la nanotecnología, incluyendo su definición como una tecnología emergente que permite agrupar átomos y moléculas para construir ordenadores a escala nanométrica. Explica brevemente los antecedentes históricos clave y las aplicaciones futuras potenciales en campos como la computación, la medicina y el medio ambiente. También menciona algunas consideraciones éticas relacionadas con esta tecnología.
El documento presenta un experimento sobre electrostática con los siguientes objetivos: estudiar la inducción de carga eléctrica en el vidrio y el plástico, y estudiar el campo eléctrico y las curvas equipotenciales generados por un sistema de cargas. El procedimiento incluye medir la carga inducida en varillas de vidrio y PVC, y trazar curvas equipotenciales usando un sensor de voltaje.
This document investigates various wavelength-shifting compounds to improve counting efficiency when 32P-Cerenkov radiation is measured in aqueous samples. Of the compounds tested, esculin, β-methyl-umbelliferon, and sodium salicylate led to the greatest improvement in counting efficiency, by factors of about 1.3, 1.2, and 1.2, respectively. The concentrations and pH levels of these compounds were also examined to determine optimal conditions. Using ethanol as a solvent along with wavelength shifters soluble in both water and ethanol did not improve counting efficiency compared to using water alone.
Comparative analysis of multi stage cordic using micro rotation techniqIAEME Publication
This document summarizes a research paper that proposes a novel pipelined multi-stage CORDIC processor architecture using a micro-rotation selection technique. The CORDIC (coordinate rotation digital computer) algorithm is used to compute trigonometric and other functions through iterative coordinate rotations. The proposed design improves speed by pipelining multiple stages of computation. It also improves efficiency by using a generalized micro-rotation sequence selection based on most-significant bit detection, avoiding complex search algorithms. The architecture reduces computation time and area requirements compared to other CORDIC implementations.
The document describes the V5 protocol, which is an open standard digital interface for integrated access between telecommunications networks and switches. It summarizes the key features and limitations of previous V1-V4 interfaces and introduces the V5 interface, which supports more flexible integrated access and dynamic time slot allocation. The V5 protocol consists of physical, data link, and application layers that allow signaling and transmission of voice calls over the digital interface using both communication and signaling channels. Call setup and release procedures using the V5 interface for PSTN services are also outlined.
AMD's new Bobcat core architecture is a low power x86 core designed for small die area and optimized for cloud clients. It features dual x86 decoders, out-of-order execution, 32KB L1 caches, a 512KB L2 cache, and advanced power reduction techniques to target sub-one watt operation. The goal of Bobcat is to provide 90% of the performance of mainstream notebook CPUs while using half the die area.
H.120 was the first digital video coding standard developed in 1984. H.261 in the late 1980s was the first widespread success and established the modern structure for video compression that is still used today. MPEG-1 and MPEG-2/H.262 built upon H.261 with improvements like bidirectional prediction and half-pixel motion compensation. H.263 further enhanced compression performance and is now dominant for videoconferencing, adding features such as overlapped block motion compensation.
The document summarizes research on using Run Length Encoding (RLE) to reduce Peak-to-Average Power Ratio (PAPR) in Orthogonal Frequency Division Multiplexing (OFDM) systems. Simulation results showed that RLE reduced PAPR by about 3 dB at a probability of 10-2 while maintaining a compression ratio of 1.7. The symbol error rate performance in additive white Gaussian noise and Rayleigh fading channels was unchanged with RLE. Thus, RLE is an effective PAPR reduction technique that does not degrade system performance.
This document provides information on SAF Tehnika's point-to-point microwave radio equipment for data and voice communication. It discusses their main product lines, which include the CFIP series for 1.4 GHz and license-free 24 GHz spectrum, offering capacities up to 720 Mbps. The CFIP series includes the CFIP-108 FODU for Fast Ethernet and the CFIP Lumina FODU for Gigabit Ethernet. It also discusses their CFIP PhoeniX split mount system for hybrid TDM/IP networks with capacities up to 366 Mbps. The document provides detailed specifications for these products.
The document summarizes a project report on comparing the MPEG-2 and H.264 video coding standards, with a focus on their main profiles. It finds that while MPEG-2 is widely used in digital broadcasting and DVD applications, H.264 provides better compression performance. However, MPEG-2 and H.264 are incompatible, but this can be addressed through transcoding. The report discusses the MPEG-2 and H.264 standards in detail and compares their encoding schemes, profiles and levels before analyzing different transcoding methods.
Pacific Quay has a core network with separately routed domains for users, television playout, radio production, post production, and a digital library. The fully converged network uses common hardware and protects core broadcast functions. It has a high bandwidth 40Gbps core with edge access switches connecting 22 hub rooms. Integration of different file formats, codecs, audio formats, metadata, and protocols between real-time and non-real-time systems presents challenges that require mapping schemas and determining if coupling is direct or loose. Questions can be directed to Brendan Mallon.
1. The document discusses different types of networking devices like repeaters, bridges, routers, and gateways and how they operate at different layers of the OSI model.
2. It provides examples of how these devices like repeaters, bridges, and routers are used to connect different local area networks and extends the physical length and coverage of a network.
3. The document also discusses concepts like routing tables, link state routing, and the Dijkstra algorithm that are used to determine the best paths between nodes in a network.
The document provides an overview of SONET (Synchronous Optical Network) standards:
1) SONET was developed to address the lack of interoperability between proprietary fiber optic transmission equipment from different manufacturers.
2) SONET defines optical carrier interfaces and rates to allow transmission of lower-rate signals at a common synchronous rate. This allows equipment from multiple vendors to interconnect.
3) SONET uses a layered approach, with section, line, and path overhead to monitor performance and isolate faults between network elements.
This document summarizes Laurent Leyssenne's thesis on the design of reconfigurable radiofrequency power amplifiers for wireless applications. The thesis aims to develop novel adaptive power amplifier architectures using silicon to improve battery life. It explores two families of adaptive mechanisms: discretized power amplifiers and adaptive bias power amplifiers. For discretized power amplifiers, it investigates architectures based on power stage bypass and parallel switched power cells to allow fast reconfiguration over a wide power range with low distortion. The switched power cell approach digitizes the envelope signal and uses control bits to dynamically modulate Volterra kernels, with quantization noise requiring oversampling and resolution techniques.
1) The document describes the FPGA implementation of a digital upconverter (DUC) and digital downconverter (DDC) for a WCDMA system.
2) The DUC converts a baseband signal to an intermediate frequency signal by upsampling and mixing with a carrier frequency. The DDC performs the opposite conversion from an intermediate frequency to baseband.
3) Both circuits were designed using Xilinx System Generator and implemented on a Virtex-4 FPGA. Experimental results verified the functionality of the DUC and DDC for WCDMA signal processing.
This document summarizes the porting and optimization of the ITU-T G.729.1 speech coding algorithm to the SC3850 DSP core. The authors modified the reference G.729.1 code to fix-point C and optimized it for the SC3850 architecture through techniques like replacing functions with intrinsics, inlining small functions, and restructuring loops and memory accesses. They achieved over 90% improvement in cycles per second (MCPS) through these optimizations while maintaining bit-exact accuracy against the ITU test vectors. The G.729.1 codec is an 8-32 kbps scalable wideband speech codec standardized by ITU, useful for applications like VoIP, audio conferencing, and
1) The document discusses techniques for envelope tracking power amplifiers, including reconfigurable depth adaptive biasing, to improve linearity and efficiency.
2) Reconfigurable depth adaptive biasing modifies the current consumption of the power amplifier based on the envelope signal using a controllable gain parameter.
3) This allows balancing nonlinear distortion effects to improve linearity, with the potential for degradation if the injected envelope exceeds a threshold. Memory effects must also be considered.
The document describes an 8-bit pipelined analog-to-digital converter (ADC) with a selectable resolution of 5-8 bits. The ADC was fabricated in a 0.13-micron CMOS process and achieves an effective number of bits of 6.10 in 8-bit mode with a 162 MHz input signal. Key aspects of the ADC include double sampling to relax amplifier settling times, redundant sign digit correction to compensate comparator offsets, and a two-stage op-amp design to provide sufficient gain and signal headroom given the low 1.2V supply voltage. Measured performance meets the requirements for medium resolution and sampling rate ADCs in modern synthetic aperture radar systems.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Presentation from SIEPON Seminar on 20 April in Czech Republic, sponsored by IEEE-SA & CAG. Opinions presented by the speakers in this presentation are their own, and not necessarily those of their employers or of IEEE.
Este documento presenta una introducción a la nanotecnología, incluyendo su definición como una tecnología emergente que permite agrupar átomos y moléculas para construir ordenadores a escala nanométrica. Explica brevemente los antecedentes históricos clave y las aplicaciones futuras potenciales en campos como la computación, la medicina y el medio ambiente. También menciona algunas consideraciones éticas relacionadas con esta tecnología.
El documento presenta un experimento sobre electrostática con los siguientes objetivos: estudiar la inducción de carga eléctrica en el vidrio y el plástico, y estudiar el campo eléctrico y las curvas equipotenciales generados por un sistema de cargas. El procedimiento incluye medir la carga inducida en varillas de vidrio y PVC, y trazar curvas equipotenciales usando un sensor de voltaje.
This document investigates various wavelength-shifting compounds to improve counting efficiency when 32P-Cerenkov radiation is measured in aqueous samples. Of the compounds tested, esculin, β-methyl-umbelliferon, and sodium salicylate led to the greatest improvement in counting efficiency, by factors of about 1.3, 1.2, and 1.2, respectively. The concentrations and pH levels of these compounds were also examined to determine optimal conditions. Using ethanol as a solvent along with wavelength shifters soluble in both water and ethanol did not improve counting efficiency compared to using water alone.
Comparative analysis of multi stage cordic using micro rotation techniqIAEME Publication
This document summarizes a research paper that proposes a novel pipelined multi-stage CORDIC processor architecture using a micro-rotation selection technique. The CORDIC (coordinate rotation digital computer) algorithm is used to compute trigonometric and other functions through iterative coordinate rotations. The proposed design improves speed by pipelining multiple stages of computation. It also improves efficiency by using a generalized micro-rotation sequence selection based on most-significant bit detection, avoiding complex search algorithms. The architecture reduces computation time and area requirements compared to other CORDIC implementations.
Information quality in personality judgment: The value of personal disclosure
Andrew Beer e Cody Brooks
Resumo: Examinada a qualidade relativa de diferentes tipos de informação e seus efeitos sobre a precisão no julgamento sobre tipos de personalidade. Trata-se do exame do uso de Informação e seus efeitos. São abordados temas como percepção; características da informação (precisão) e aspectos de qualidade. Aplicação específica de um campo de conhecimento.
Local: Journal of Research in Personality 45 (2011) 175–185
The document provides an introduction to cryptography including definitions of terms and topics covered. It discusses symmetric-key cryptography and algorithms like substitution ciphers, transposition ciphers, DES, AES and their modes of operation. It also covers asymmetric-key cryptography including RSA and Diffie-Hellman key exchange with examples of encrypting and decrypting messages.
Wireless Reducing Overall Delay In Multi Radio WobanShahab Shahid
The document proposes a technique to reduce overall delay in multi-radio wireless-optical broadband access networks (WOBANs) with minimal per-node processing overhead on data packets. WOBANs combine the high-speed, high-bandwidth optical back-end with a wireless front-end to provide flexible broadband access. However, the wireless front-end introduces delays from transmission, queueing, and synchronization at nodes. The authors aim to minimize these delays to match the performance of the optical back-end. They discuss existing routing algorithms for WOBANs and their limitations in addressing delays and load balancing. The proposed technique is intended to choose paths with minimal delay and maximize throughput while balancing network loads.
This article summarizes the story of five orphaned siblings - Keren, Corrie, Kimberly, Nathaniel, and Benjamin Bunnell - who lost both of their parents to cancer within a year of each other. The oldest sibling, Keren, became the legal guardian of her younger brothers and sisters at age 21. Despite their loss, the siblings have stayed close through their shared faith and musical talents, with Keren providing stability and leadership. They continue to cope with the grief of losing both parents at a young age.
The document summarizes research comparing different modulation formats for an 8 channel wavelength division multiplexed (WDM) optical network operating at 40 Gbps per channel (320 Gbps total). It analyzes the performance of non-return-to-zero (NRZ), return-to-zero (RZ) with duty cycles of 0.5 and 0.67, carrier-suppressed return-to-zero (CSRZ), duo binary RZ (DRZ) and modified duo binary RZ (MDRZ) modulation formats. It varies the input power and transmission distance to evaluate each format's tolerance to nonlinearity. Dispersion compensation is performed using dispersion compensating fiber in a symmetrical configuration. The best modulation format is
Revista brazilian journal of analytical chemistry - 1patfrg
The Brazilian Journal of Analytical Chemistry (BrJAC) is launching to promote discussion around the role of analytical chemistry in Brazil's development. BrJAC will publish scientific papers and editorials to foster academic-industrial integration and innovation. Analytical chemistry is important as technological innovation plays a larger role in public policy and business in Brazil. The journal aims to help change Brazil's scenario where most PhD students remain in academia rather than working in industry.
Radio is a form of wireless communication that uses electromagnetic waves of frequencies below visible light to transmit signals. Radio waves are produced by oscillating electric currents and can travel through space. Antennas are devices that convert the electric currents into radio waves for transmission and pick up radio waves for reception, allowing communication over long distances. In the late 1800s, Guglielmo Marconi began working on developing radio into a commercial wireless telegraph system and built some of the first radio transmission equipment, making discoveries about how antenna height impacts transmission range.
Numbers are used for more than just math, as they are essential for keeping track of dates in history, labeling and describing in science, and identifying pages when reading. Numbers are ubiquitous in everyday life as well, appearing on clocks, streets, and at sporting events to help quantify and organize information.
This document tests the compatibility of document formatting and elements across different applications. It contains various formatted text, images, tables, and other elements to check if they display correctly when opened in other word processors besides the original Microsoft Word format. The document tests things like bulleted lists, styles, colors, links, fonts, headers/footers, comments, track changes, comments, and more. The goal is to determine what formatting and elements are compatible across applications for editing documents on different devices.
The document discusses the PROMISE community and ways its members can collaborate more effectively. It describes several case studies where collaboration between PROMISE researchers led to improved results, new data, and funding opportunities. It then proposes several online tools like chat rooms, discussion forums, and code libraries to further foster collaboration within the PROMISE community between annual meetings.
This document summarizes several geographical routing protocols for wireless sensor networks:
1) Small World Topology-Aware Routing (SWTAR) uses topological awareness to discover routes and avoid voids, achieving high delivery ratios with short paths.
2) Geographic Wireless Reliable Multicast (GeoWiReM) provides efficient multicast delivery within ad hoc regions using passive acknowledgments and local recovery.
3) Energy-aware interference-sensitive geographic routing (EIGR) minimizes energy use and interference by selecting next hops along an anchor list that guides packets along energy-optimal low-interference paths.
Adequate and Precise Evaluation of Predictive Models in Software Engineering ...Tim Menzies
The document discusses challenges in evaluating software defect prediction models and summarizes key points:
1. Experimental results in research papers are often inadequately reported, hiding shortcomings of machine learning algorithms on imbalanced and correlated defect data.
2. Performance measures like accuracy can provide a one-sided view, and alternatives like F-measure and G-mean are proposed to better capture performance.
3. Visual tools like ROC curves and margin plots are useful for comparing classifiers, revealing their flexibility at different operational points depending on misclassification costs.
Este documento presenta el método de investigación mixta, el cual integra métodos cuantitativos y cualitativos para obtener una perspectiva más amplia y profunda del fenómeno bajo estudio. El método mixto busca utilizar las fortalezas de ambos enfoques y minimizar sus debilidades, produciendo datos más ricos y variados. Además, fomenta la creatividad teórica y permite llevar a cabo indagaciones más dinámicas.
International Refereed Journal of Engineering and Science (IRJES) is a peer reviewed online journal for professionals and researchers in the field of computer science. The main aim is to resolve emerging and outstanding problems revealed by recent social and technological change. IJRES provides the platform for the researchers to present and evaluate their work from both theoretical and technical aspects and to share their views.
www.irjes.com
Road accidents are a major cause of deaths in India, with over 1,330 people dying every day. Rash driving by young people is a primary reason, as many drive recklessly at high speeds without following traffic rules after getting a new vehicle. Not wearing helmets and drinking alcohol are also significant contributing factors. Parents share responsibility when they give vehicles to youngsters before they are properly trained, or are unaware that their children are consuming alcohol. Everyone needs to drive safely and follow traffic rules to protect both themselves and others.
Tranzeo has announced a new TR-5amp series of 5GHz radios that can function as an access point, point-to-point bridge, or client adapter. The radios have dual Ethernet ports, support for tunneling protocols like VPN, and security features including WPA and WEP. They also have alignment LEDs, adjustable transmit power, and high gain external antenna options up to 32dBi.
This document provides an overview and analysis of coding techniques used in 4G LTE-Advanced networks. It describes the core coding steps of randomization, Reed-Solomon encoding, convolutional encoding, interleaving, and modulation. Reed-Solomon coding uses a (255,239) block with 8 bytes of error correction. Convolutional encoding uses a rate 1/2 constraint length 7 code. Interleaving is performed between convolutional and Reed-Solomon encoding to improve performance. Coding blocks are then mapped to the time domain with IFFT and a cyclic prefix is added before transmission over the channel.
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International Journal of Computational Engineering Research(IJCER)
1. International Journal Of Computational Engineering Research (ijceronline.com) Vol. 2 Issue. 8
Implementation of an OFDM FFT Kernel for WiMAX
Lokesh C. 1, Dr. Nataraj K. R.2.
1
Assistant Professor,Department of Electrical and Electronics Engineering.Vidyavardhaka College of Engineering,
Mysore, Karnataka, India.
2
Professor, Department of Electronics and Communications Engineering.SJB Institute of Technology, Bangalore,
Karnataka, India.
Abstract:
In this paper we focus on the OFDM Kernel which refers to the inverse fast Fourier transform and cyclic
prefix insertion blocks in the downlink flow and the FFT and cyclic prefix removal blocks in the uplink flow. To
support orthogonal frequency-division multiple access (OFDMA) an extension to the OFDM kernel is required that
allows each user to be allocated with a portion of the available carriers. This process is referred to as sub
channelization. The WiMAX building blocks include bit-level, OFDMA symbol-level, and digital intermediate
frequency processing blocks. For bit-level processing, Altera provides symbol mapping/demapping reference
designs and support for forward error correction using the Reed- Solomon and Viterbi MegaCore® functions. The
OFDMA symbol-level processing blocks include reference designs that demonstrate subchannelization and
desubchannelization with cyclic prefix insertion supported by the fast Fourier transform, and inverse fast Fourier
transform MegaCore functions. Other OFDMA symbol-level reference designs illustrate ranging, channel
estimation, and channel equalization. The digital IF processing blocks include single antenna and multiantenna
digital up converter and digital down converter reference designs, and advanced crest-factor reduction and digital
predistortion.
Keywords: inverse fast Fourier transform (IFFT), orthogonal frequency-division multiple access (OFDMA),
intermediate frequency (IF), forward error correction (FEC), digital up converter (DUC), digital down converter
(DDC), crest-factor reduction (CFR), digital predistortion (DPD, WiMAX (Worldwide Interoperability for
Microwave Access).
1. Introduction
The Altera® orthogonal frequency division multiplexing (OFDM) kernel can be used to accelerate the
development of wireless OFDM transceivers such as those required for the deployment of mobile broadband
wireless networks based on the IEEE 802.16 standard. OFDM is one of the key physical layer components
associated with mobile worldwide interoperability for microwave access (WiMAX) and is widely regarded as an
enabling technology for future broadband wireless protocols including the 3GPP and 3GPP2 long term evolution
standards.
The OFDM kernel has the following key features:
Support for 128, 512, 1K, and 2K FFT sizes to address variable bandwidths from 1.25 to 20 MHz
Parameterizable design
Optimized for efficient use of Cyclone II, Stratix II, and Stratix III device resources
2. Introduction to WiMAX
WiMAX (Worldwide Interoperability for Microwave Access) is a wireless communications standard
designed to provide 30 to 40 megabit-per-second data rates, with the 2011 update providing up to 1 Gbit/s for fixed
stations. WiMAX refers to interoperable implementations of the IEEE 802.16 family of wireless-networks standards
ratified by the WiMAX Forum. Similarly, Wi-Fi, refers to interoperable implementations of the IEEE 802.11
Wireless LAN standards certified by the Wi-Fi Alliance. WiMAX Forum certification allows vendors to sell fixed or
mobile products as WiMAX certified, thus ensuring a level of interoperability with other certified products, as long
as they fit the same profile.
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2. International Journal Of Computational Engineering Research (ijceronline.com) Vol. 2 Issue. 8
MAC/PHY Interface
Randomization Derandomization
Uplink
Downlink
FEC Encoding FEC Decoding
Interleaving Deinterleaving
Bit Level Processing
Symbol Mapping Symbol Demapping
Subchannalization Channel Estimation and Equilization To MAC
Plot Insertion
Desubchannalization
plot extension OFDMA Ranging
IFFT
FFT
OFDM Symbol Level
Cyclic Prefix
Processing
Remove Cyclic prefix
DUC DDC
CFR Digital IF Processing
From ADC
DPD
To DAC
Figure 1. WiMAX Physical Layer Implementatio, an overview of the IEEE 802.16e-2005 scalable orthogonal
frequency-division multiple access (OFDMA) physical layer (PHY) for WiMAX basestations.
Altera’s WiMAX building blocks include bit-level, OFDMA symbol-level, and digital intermediate
frequency (IF) processing blocks. For bit-level processing, Altera provides symbol mapping/demapping reference
designs and support for forward error correction using the Reed- Solomon and Viterbi MegaCore® functions. The
OFDMA symbol-level processing blocks include reference designs that demonstrate subchannelization and
desubchannelization with cyclic prefix insertion supported by the fast Fourier transform, and inverse fast Fourier
transform MegaCore functions. Other OFDMA symbol-level reference designs illustrate ranging, channel
estimation, and channel equalization. The digital IF processing blocks include single antenna and multiantenna
digital up converter and digital down converter reference designs, and advanced crest-factor reduction and digital
predistortion.
3. Introduction to OFDM Kernal
The OFDM Kernel refers to the inverse fast Fourier transform (IFFT) and cyclic prefix insertion blocks in
the downlink flow and the FFT and cyclic prefix removal blocks in the uplink flow. To support orthogonal
frequency-division multiple access (OFDMA) an extension to the OFDM kernel is required that allows each user to
be allocated with a portion of the available carriers. This process is referred to as subchannelization. The physical
layer is based around OFDM modulation. Data is mapped in the frequency domain onto the available carriers. For
this data to be conveyed across a radio channel, it is transformed into the time domain using an inverse fast Fourier
transform (IFFT) operation. To provide multipath immunity and tolerance for synchronization errors, a cyclic prefix
is added to the time domain representation of the data. Multiple modes are supported to accommodate variable
channel bandwidths. This scalable architecture is achieved by using different FFT/IFFT sizes. This reference design
supports transform sizes of 128, 512, 1,024, and 2,048.
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3. International Journal Of Computational Engineering Research (ijceronline.com) Vol. 2 Issue. 8
4. Implementing OFDM Kernal for WiMAX
FPGAs are well suited to FFT and IFFT processing because they are capable of high speed complex
multiplications. DSP devices typically have up to eight dedicated multipliers, whereas the Stratix III EP3SE110
FPGA has 112 DSP blocks that offer a throughput of nearly 500 GMACs and can support up to 896 18x18
multipliers, which is an order of magnitude higher than current DSP devices.
Sign a
Zero Loopback sign b
Zero Acc round
clk [3..0] zero Chain ouyt saturate
ena [3..0] Round Chain out rotate
Chain In Chain out
alcr [3..0] Saturate Chain out Shift Saturation /
Previous Cascade Overflow
Data A0
First Stage Adder
Second Stage Adder / Accumulator
Second Adder Register Bank
Second Round / Saturation
Data B0
First Round / Saturate
Pipelined Register bank
Output Register bank
Input register bank
Chain out Adder
Data A1
Shift / Rotate
Data Out
MUX
Data B1
Data A2
First Stage Adder
Data B2
Data A3
Data B3
Half DSP Block
Next Cascade
Figure2. Embedded DSP Blocks Architecture in Stratix III Devices
Such a massive difference in signal processing capability between FPGAs and DSP devices is further
accentuated when dealing with basestations that employ advanced, multiple antenna techniques such as space time
codes (STC), beam forming, and multiple-input multiple-output (MIMO) schemes. The combination of OFDMA
and MIMO is widely regarded as a key enabler of higher data rates in current and future WiMAX and 3GPP long
term evolution (LTE) wireless systems. When multiple transmit and receive antennas are employed at a basestation,
the OFDMA symbol processing functions have to be implemented for each antenna stream separately before MIMO
decoding is performed. The symbol-level complexity grows linearly with the number of antennas implemented on
DSPs that perform serial operations. For example, for two transmit and two receive antennas the FFT and IFFT
functions for WiMAX take up approximately 60% of a 1-GHz DSP core when the transform size is 2,048 points. In
contrast, a multiple antenna-based implementation scales very efficiently when implemented with FPGAs. Using
Altera devices, we can exploit parallel processing and time-multiplexing between the data from multiple antennas.
The same 2×2 antenna FFT/IFFT configuration uses less than 10% of a Stratix II 2S60 device.
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5. Functional description of OFDM kernal for WiMAX
Altera provides the reference design as clear text VHDL. The reference design also demonstrates the use of
the FFT MegaCore function. To accelerate integration with Altera intellectual property (IP) or other subsystems, the
interfaces support the Altera Avalon® Streaming (Avalon-ST) interface specification. Altera has verified the RTL
behavior against a fixed point model of the algorithms. The reference design includes RTL testbenches that
stimulate the designs using golden reference data from the fixed point model and check for correct functionality.
The OFDM kernel handles the FFT operations and cyclic prefix addition and removal. The FFT size is a parameter
that we must specify at synthesis time, but we can change the guard interval at run time.
Downlink Transmit
The downlink OFDM kernel module performs an inverse Fourier transform of the frequency domain input
data and adds a cyclic prefix to the resulting time domain data. The cyclic prefix addition block contains a controller
that buffers the output packets from the FFT, and adds the appropriate proportion of the end of the output packet to
the beginning of the output packet. As this requires a fairly significant memory resource, the hardware architecture
has been designed so that the embedded memory may be shared with the uplink OFDM kernel if the modem is
operating in time division duplex (TDD) mode.
Avalon – ST Embedded
status source memory
Interface
Avalon – ST
Avalon – ST IFFT Mega Add Cyclic data source
Data Sink Core Function Prefix Interface
Interface
Clock 2
Clock 1
Figure 3 shows a block diagram of the downlink OFDM kernel.
Interface Specifications
The block has two clock domains. In addition, there are two reset ports; one for each clock domain. The
reset ports are active low. Figure 4 shows the downlink OFDM kernel interfaces.
cp_width Configuration Interface cp_width_out
din_ready dout_ready
cp_width
din_valid dout_valid
Avalon – Avalon –
cp_width
din_real ST Sink ST Source
Interface dout_r
Interface
din_imag cp_width
dout_i
din_start_block
dout_exp
add_cp_rdy Status source Interface dout_start_block
Figure4. Downlink OFDM Kernel Interfaces
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5. International Journal Of Computational Engineering Research (ijceronline.com) Vol. 2 Issue. 8
The input interface has the following features:
Avalon-ST data sink and status source
Ready signal latency of one cycle—the earliest time valid data may be presented to the block after ready has
been signaled is one clock cycle
The output interface has the following features:
Avalon-ST data source
Ready signal latency of four cycles—the block responds to new data or stops delivering data four cycles after
an event on the ready signal
Support for back pressure and Dynamically changeable cyclic prefix
Uplink Receive
The uplink OFDM kernel module performs an FFT of the time domain input data and removes the cyclic
prefix. The Avalon-ST start of packet pulse should specify the start of the cyclic prefix. The remove cyclic prefix
block ignores the data during the cyclic prefix and writes the remaining samples to the FFT input buffer.
Embedded
memory
Avalon – ST IFFT Mega Add Cyclic Avalon – ST
Data Sink Core Function Prefix data source
Interface Interface
Clock 1 Clock 2
Figure5. Uplink OFDM Kernel Block Diagram
Because the channel characteristics can change, it is possible that the start of the packet pulse is not always
after the start of the cyclic prefix time. The hardware has been designed to deal with this scenario but with the
constraints that the variation of the pulse must be within the cyclic prefix time and that the start pulse will not be
before the preceding symbol has been fully clocked in.
Uplink Interface Specifications
The block has two clock domains. In addition, there are two reset ports; one for each clock domain. The
reset ports are active low.
Configuration Interface dout_ready
cp_width
cp_width
dout_valid
din_ready
cp_width
dout_r
din_valid
Avalon – Avalon – cp_width
dout_i
din_real ST Sink ST Source
Interface Interface
din_imag dout_exp
din_start_block dout_start_block
dout_end_block
Figure6. Uplink OFDM Kernel Interfaces
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The input interface has the following features:
Avalon-ST data sink
Ready signal latency of one cycle
Does not apply back pressure since data is continuous from RF card
The output interface has the following features:
Avalon-ST data source
Ready signal latency of one cycle
Does not accept back pressure from downstream sink
Dynamically changeable cyclic prefix
FFT MegaCore Function
The FFT MegaCore function is capable of performing both the forward and inverse transform. The
hardware architecture is chosen to minimize the resource usage and has the following parameters:
Burst mode
Single output engine
Single instance of engine
16-bit internal and data input/output precision widths
In addition, design implements two clock domains so that it is possible to exploit time sharing and
minimize resource utilization in the FFT MegaCore function by running Clock 1 faster than Clock 2. The FFT
MegaCore function generates block floating point output data and the output dynamic range is maximized for the
given input and output data widths.
Clock Requirements
The clocking requirements are as follows:
The two clock domains must be synchronous
The minimum Clock 2 frequency is the data sampling frequency given in Table 1. This would lead to a
constant output from the FFT MegaCore function
FFT Points Bandwidth (MHz) Clock 2 (MHz)
128 1.25 1.429
256 2.5 2.857
512 5 5.714
1,024 10 11.429
2,048 20 22.857
Table 1. Minimum Clock 2 Rate
The Clock 2 frequency may equal or exceed the Clock 1 frequency
The Clock 1 requirements are dictated by the FFT MegaCore function and are summarized in Table 2
FFT Points Required data rate FFT throughput Clock 1 minimum
(MHz) (Cycles/ N block) Speed (MHz)
128 1.429 858 9.579
256 2.857 1,626 18.146
512 5.714 3,693 41.214
1,024 11.429 7,277 81.220
2,048 22.857 16,512 184.285
Table 2. Clock 1 Requirements
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7. International Journal Of Computational Engineering Research (ijceronline.com) Vol. 2 Issue. 8
Table 2 ignores the cyclic prefix effect, which reduces the Clock 1 speed requirement slightly
The Clock 1 minimum speed = throughput/N × data rate
6. Conclusion
This application note has outlined the advantages of using Altera FPGAs for implementing OFDM systems
such as an IEEE 802.16e deployment. A flexible, high-throughput DSP platform needs an FPGA-based
implementation platform. In addition, this reference design demonstrates the implementation of a key function that
may be exploited to facilitate rapid system deployment.
7. Results
Symbol generator simulation output of an OFDM kernel for WiMAX as obtained in Model Sim®
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8. International Journal Of Computational Engineering Research (ijceronline.com) Vol. 2 Issue. 8
References
[1] K. Fazel and S. Kaiser, Multi-Carrier and Spread Spectrum Systems: From OFDM and MC-CDMA to LTE
and WiMAX, 2nd Edition, John Wiley & Sons, 2008, ISBN 978-0-470-99821-2
[2]. M. Ergen, Mobile Broadband - Including WiMAX and LTE, Springer, NY, 2009 ISBN 978-0-387-68189-4
[3]. Carl Weinschenk (April 16, 2010). "Speeding Up WiMax". IT Business Edge. "Today the initial WiMax
system is designed to provide 30 to 40 megabit-per-second data rates."
[4]. Wimax Forum Industry Research Report
http://www.wimaxforum.org/sites/wimaxforum.org/files/page/2011/03/Monthly_Industry_Report_March20
11.pdf
[5] Synthesis of band-limited orthogonal signals for multi-channel data transmission, Bell System Technical
Journal 46, 1775-1796.
[6] MATLAB 7.8.0 (R2009a), Help. s.l. : MathWorks, Inc., 2009.
[7] van Nee, R. and Prasad, R. OFDM for Wireless Multimedia Communications. s.l. : Artech House, 2000.
[8] Charan Langton. OFDM. Intuitive Guide to Principles of Communications. http://www.complextoreal.com/.
[9] Amalia Roca Persiva . Implementation of a WiMAX simulator in Simulink. Institute of Communications &
Radio-Frequency Engineering, Vienna University of Technology. Vienna : s.n., 2007. Master Thesis.
Issn 2250-3005(online) December| 2012 Page 81