正交頻分復(fù)用技術(shù)（Orthogonal Frequency Division MULTIPLEXING， OFDM）非常適合高速通信系統(tǒng)，但存在高峰均功率比（PAPR）的問(wèn)題。對(duì)OFDM系統(tǒng)中如何降低PARR的問(wèn)題進(jìn)行了研究，討論了降低PAPR的主要方法，重點(diǎn)分析了選擇性映射法（SLM），并在此基礎(chǔ)上提出了一種基于預(yù)編碼矩陣的改進(jìn)算法，最后通過(guò)matlab進(jìn)行了算法仿真，仿真結(jié)果表明，改進(jìn)算法在使得OFDM系統(tǒng)在降低峰均功率比的性能上得到了進(jìn)一步的改善。
Abstract: While many questions still surround the creation and deployment of the smart grid, the need for a reliablecommunications infrastructure is indisputable. Developers of the IEEE 1901.2 standard identified difficult channel conditionscharacteristic of low-frequency powerline communications and implemented an orthogonal frequency division MULTIPLEXING (OFDM)architecture using advanced modulation and channel-coding techniques. This strategy helped to ensure a robust communicationsnetwork for the smart grid.
正交頻分復(fù)用 （Orthogonal Frequency Division MULTIPLEXING，OFDM）是一種多載波調(diào)制技術(shù)，由于具有良好的抗多徑干擾性能，適用于高速數(shù)據(jù)傳輸，OFDM成為近年來(lái)人們研究的熱點(diǎn)。但是其峰均比較高，應(yīng)用受到了限制，因此有必要研究降低PAPR的方法。本文首先介紹了OFDM的基本原理和PAPR的基本概念，然后討論了目前常用的降低PAPR的方法，最后對(duì)SLM和PTS方法進(jìn)行了MATLAB仿真。
This application note covers the design considerations of a system using the performance
features of the LogiCORE™ IP Advanced eXtensible Interface (AXI) Interconnect core. The
design focuses on high system throughput through the AXI Interconnect core with F
MAX
and
area optimizations in certain portions of the design.
The design uses five AXI video direct memory access (VDMA) engines to simultaneously move
10 streams (five transmit video streams and five receive video streams), each in 1920 x 1080p
format, 60 Hz refresh rate, and up to 32 data bits per pixel. Each VDMA is driven from a video
test pattern generator (TPG) with a video timing controller (VTC) block to set up the necessary
video timing signals. Data read by each AXI VDMA is sent to a common on-screen display
(OSD) core capable of MULTIPLEXING or overlaying multiple video streams to a single output video
stream. The output of the OSD core drives the DVI video display interface on the board.
Performance monitor blocks are added to capture performance data. All 10 video streams
moved by the AXI VDMA blocks are buffered through a shared DDR3 SDRAM memory and are
controlled by a MicroBlaze™ processor.
The reference system is targeted for the Virtex-6 XC6VLX240TFF1156-1 FPGA on the
Xilinx® ML605 Rev D evaluation board
This paper considers semiblind channel estimation
and data detection for orthogonal frequency-division MULTIPLEXING
(OFDM) over frequency-selective fading channels.
This project aim was to build wireless software modem for data communication
between two computers using an acoustic interface in the voice frequency range (20Hz–
20,000Hz). The transmitting antenna is a speaker (frequency response of: 90Hz –
20,000Hz) and the receiving antenna is a microphone (frequency response of: 100Hz –
16,000Hz). The test files used as information files were text files.
This goal was attained both in an incoherent scheme and in a coherent scheme.
Build under Matlab code, our modem uses OFDM (orthogonal frequency division
MULTIPLEXING) modulation, synchronization by LMS sequence, channel estimation (no
equalizer) via pilot tones. The symbols are either PSK or ASK for a constellation size of
2 or 4. To optimize the probability of error, these symbols were mapped using Gray
mapping.
Report
The TJA1040 is an advanced high speed CAN transceiver for use in
automotive and general industrial applications. It supports the differential
bus signal representation described in the international standard for
in-vehicle high speed CAN applications (ISO11898). CAN (Controller Area
Network) is the standard protocol for serial in-vehicle bus communication,
particularly for Engine Management and Body MULTIPLEXING.
The TJA1040 provides a Standby mode, as known from its functional
predecessors PCA82C250 and PCA82C251, but with significantly
reduced power consumption. Besides the excellent low-power behavior
the TJA1040 offers several valuable system improvements. Highlights are
the absolute passive bus behavior if the device is unpowered as well as
the excellent EMC performance.
This book gives a comprehensive overview of the technologies for the advances of
mobile radio access networks. The topics covered include linear transmitters,
superconducting filters and cryogenic radio frequency (RF) front head, radio over
fiber, software radio base stations, mobile terminal positioning, high speed
downlink packet access (HSDPA), multiple antenna systems such as smart
antennas and multiple input and multiple output (MIMO) systems, orthogonal
frequency division MULTIPLEXING (OFDM) systems, IP-based radio access networks
(RAN), autonomic networks, and ubiquitous networks.
