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Description: matlab信道模型，用于模拟OFDM系统对ISI的改善。-Matlab channel model to simulate OFDM system to improve the ISI.
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Size: 1238 |
Author: 客户 |
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Description: matlab信道模型，用于模拟OFDM系统对ISI的改善。-Matlab channel model to simulate OFDM system to improve the ISI.
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Size: 1024 |
Author: 客户 |
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Description: OFDM程序，这么安排矩阵的目的是为了构造共轭对称矩阵
共轭对称矩阵的特点是 在ifft/fft的矢量上 N点的矢量
在0，N/2点必须是实数 一般选为0
1至N/2点 与 （N/2）+1至N-1点关于N/2共轭对称- BPSK simulation using a carrier cosine wave with ISI
clc
close all
clear all
figure(1)
n=160
for i=1:n
data(i)= 2*round(rand)-1
end
create modulated BPSK signal
first expand the bit stream
exdata=[]
for i=1:length(data)
for rep=1:5
exdata= [exdata data(i)]
end
end
ts=.1
t=1:ts:80.9
carrier=cos(pi*t)
multiply expanded bitstream by cosine wave with carrier frequency
this is the BPSK that is to be transmitted over the channel
bpsk=carrier.*exdata
bpsk=[bpsk(length(bpsk)-1) bpsk(length(bpsk)) bpsk]
plot(bpsk)
generating the noise
p=rand(1,800)*2*pi
p=rand*2*pi
snr=10
r=sqrt(-1*(1/snr*log(1- rand)))
no = 5*(r.* exp(j*p))
no = (r.* exp(j*p))
value of alpha
al=rand+j*rand
al=1
Spreading channel with the alpha as the variable
for k=5:5:795
for l = 1:5
al=round(rand)+j*round(rand)
rec(k+l)=bpsk(k+l)+al*bpsk(k-5+l)
end
end
rxdata=rec+ no
begin demodulation
first multiply recie
Platform: |
Size: 6146048 |
Author: 卞敏捷 |
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Description:
应用OFDM可以有效地对抗多径时延扩展。循环前缀不仅可以消除符号间干扰（ISI），还能消除子载波间干扰（ICI).本项目完整地仿真了OFDM系统。-Application of OFDM can effectively combat multipath delay spread. Cyclic prefix can not only eliminate inter-symbol interference (ISI), can eliminate Inter-carrier interference (ICI). This project a complete simulation of the OFDM system.
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Size: 41984 |
Author: 吏继斌 |
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Description: 正交频分复用源程序，交含逆快速傅立叶变换，ISI，傅立叶变换-main OFDM
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Size: 38912 |
Author: coofy |
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Description: 正交频分复用技术是近年来发展起来的新技术,在高速无线数据传输领域有很大的应用前景。文章在分析和总结相关文献的基础上,介绍了正交频分复用(OFDM)技术的发展历史,讨论了正交频分复用技术的基本原理和实现方法。通过分析表明,在高速无线通信中OFDM对于消除符号间干扰(ISI),降低系统的复杂度等方面具有很大优势。正交频分复用(OFDM)是一种多载波宽带数字调制技术,它能有效地克服传输中的多径干扰和消除码间串扰,适合于高速率的地面信道视频传输。本文就OFDM技术进行了较为详尽的分析,并对OFDM的传输特性进行了基于FFT算法实现的MATLAB软件模拟及模拟结果分析。 -OFDM is a new technology developed in recent years, high-speed wireless data transmission in the field of great applications. This paper analyzes and summarizes the basis of relevant literature, describes orthogonal frequency division multiplexing (OFDM) technology, history, orthogonal frequency division multiplexing discussed the basic principles and implementation methods. The analysis shows that in the high-speed wireless communication in OFDM symbol for the elimination of interference (ISI), and so reduce the complexity of the system has great advantages. Orthogonal frequency division multiplexing (OFDM) is a multi-carrier wideband digital modulation techniques, can effectively overcome the transmission of multi-path interference and the elimination of intersymbol interference, the ground for high-speed video transmission channel. In this paper, OFDM technology, a more detailed analysis, and transmission characteristics of OFDM FFT algorithm based on the MATLAB software simulation
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Size: 71680 |
Author: 罗萍 |
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Description: 传统均衡器无法有效地同时对抗这两种信道衰落，而Turbo均衡技术作为一种联合信道均衡和信道译码的方法，能有效地对抗符号间干扰（ISI），提供迭代增益，提高接收机的整体性能。因此，本文根据下一代无线通信系统的设计要求，分别对单载波和OFDM系统的Turbo均衡算法进行了研究。
-Conventional equalizer can not effectively fight both at the same time fading, while the Turbo equalization as a joint channel equalization and channel decoding method is robust against inter-symbol interference (ISI), provides iteration gain, improved receiver overall performance. Therefore, this next-generation wireless communication system according to the design requirements, namely, the single carrier and OFDM systems Turbo equalization algorithm is studied.
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Size: 703488 |
Author: w |
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Description: the paper is relavent to ISI and ICI that occurs in wireless medium
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Size: 197632 |
Author: shining |
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Description: Orthogonal Frequency Division Multiplexing (OFDM) is a multicarrier modulation method with the initial idea to overcome multipath fading in a wireless environment. Multipath effect causes an unacceptable symbol in multiple copies but with a different time causing inter symbol interference (ISI) between the symbols in the receiver.
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Size: 1024 |
Author: oktavia |
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Description: Modern wireless communication systems are expected to support high data rate, allowing users to access high quality multimedia content, anytime-anywhere. To support high data rate, wideband frequency channels are required. However, frequency selective fading over wideband channels introduces inter-symbol interference (ISI) which in turn causes effective throughput to go below required level. Introduction of OFDM transforms wideband frequency selective fading problem to narrowband flat fading and solves the problem of ISI. Symbol detection under flat fading is simple and complicated equalizers at the receiver are not required.
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Size: 655360 |
Author: ravi |
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Description: 一种新的符号定时和载波频率同步算法,该算法将OFDM符号分成几部分。它使用相关性和积累在几个OFDM
符号获得估计函数。当部分的长度小于ISI自由地区,该算法可以识别它。然后估计的最优符号定时和载波频率偏移可以获得。计算机仿真结果表明,该算法不仅可以跟踪时变信道变化但也有较小的MSE比ML估计算法。-A new symbol timing and carrier frequency synchronization algorithm is presented and the algorithm divides the OFDM symbol into several parts. It uses correlation and accumulation in several OFDM
symbols to acquire estimation function. When the length of part is smaller than that of ISI free region , the algorithm can distinguish it. Then the estimation of optimal symbol timing and carrier frequency offset can be acquired .The computer simulation results show that the proposed algorithm not only can track time varying channel change but also has smaller MSE than that of ML
estimation algorithm.
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Size: 276480 |
Author: wujueying |
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Description: Multicarrier modulations attract a lot of attention ranging from wireline to wireless
communications compared to single carrier modulation because of theirs capability to
efficiently cope with frequency selective fading channels. Much of attention in the present
literature emphasizes on the use of conventional OFDM, which is able to avoid both inter -
symbol interference (ISI) and inter - channel interference (ICI) making use of a suitable cyclic
prefix.
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Size: 183296 |
Author: archana |
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Description: In a single carrier communication system, the symbol period must be much greater than the delay time in order to avoid inter-symbol interference (ISI) [1].-In a single carrier communication system, the symbol period must be much greater than the delay time in order to avoid inter-symbol interference (ISI) [1].
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Size: 9848832 |
Author: manita |
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Description: orthogonal division multiplixing(ofdm) is a new scheme used in wireless communication systems its also called multicarrier system and achieved this. cyclic prefix is used to minimize the intersymbol interference(ISI) and intercarrier interference
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Size: 1024 |
Author: awatif |
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Description: OFDM is multicarrier modulation (MCM) technique which provides an efficient means to
handle high speed data streams on a multipath fading environment that causes ISI. Normally
OFDM is implemented using FFT and IFFT’s. To decrease the BW waste brought by adding
cyclic prefix, wavelet based OFDM is employed.-OFDM is multicarrier modulation (MCM) technique which provides an efficient means to
handle high speed data streams on a multipath fading environment that causes ISI. Normally
OFDM is implemented using FFT and IFFT’s. To decrease the BW waste brought by adding
cyclic prefix, wavelet based OFDM is employed.
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Size: 37888 |
Author: awatif |
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Description: OFDM is multicarrier modulation (MCM) technique [1] which provides an efficient means to
handle high speed data streams on a multipath fading environment that causes ISI. Normally
OFDM is implemented using FFT and IFFT’s. To decrease the BW waste [4] brought by adding
cyclic prefix, wavelet based OFDM is employed.
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Size: 1024 |
Author: awatif |
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Description: 仿真OFDM传输系统，仿真不同的保护间隔的ISI影响，信道为AWGN或多径瑞利衰落信道。-Simulation OFDM transmission system, ISI impact simulation of different guard interval, the channel is AWGN or Rayleigh fading channels.
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Size: 2048 |
Author: stanshao |
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Description: 从抗ISI和ICI的角度来讲，总是希望能量集中在时频格点附近，而扩散到其他格点的能量越小越好，TFL正是描述这一特性的最直接的方法，从滤波器的角度看，TFL特性描述两个滤波器之间的相关性，描述TFL特性的方法包括TFL函数和TFL参数两大类，TFL函数又包含瞬时相关函数、模糊函数和干扰函数，而TFL参数包括Heisenberg参数和方向参数。
本代码使用matlab仿真常见的高斯、IOTA和HSIN等滤波器，与矩形滤波器进行对比与分析。(This code uses MATLAB to simulate common filters such as Gauss, IOTA and HSIN, and compares and analyzes rectangular filters.)
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Size: 1061888 |
Author: 圆妮
|
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Description: In a single carrier communication system, the symbol period must be much
greater than the delay time in order to avoid inter-symbol interference (ISI) [1].
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Size: 9832448 |
Author: N123 |
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Description: One of the major challenges which prevents the coordinated multipoint (CoMP) communications concept from being widely deployed in new cellular systems is timing synchronization. In order to achieve the gains promised by CoMP systems, the user equipments’ (UEs) signals in uplink (UL) or the base stations’ (BSs) signals in downlink (DL) should be synchronized such that the time difference of arrivals (TDOAs) do not exceed the cyclic prefix (CP) length of the transmitted signals; Otherwise the system suffers from unavoidable integer time offsets. These offsets lead to asynchronous interference in terms of inter-carrier, inter-block and inter-symbol interference (ISI). This limits the percentage of area within a cell which can be covered by cooperation and imposes an upper bound on this area. In this paper, we investigate this problem in the UL and by using geometrical and semi-analytical approaches, we define this upper bound. Also, by characterizing an accurate mathematical model for the asynchronous interference in Rayleigh fading channels, we were be able to employ a standard MMSE-based receiver that mitigates this interference. Furthermore, a typical joint channel and delay estimation block is incorporated into the receiver to examine its performance with estimation errors.
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Size: 1869319 |
Author: ahamza |
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