Description: 文章中分析了OFDM系统的频谱利用率，研究了OFDM系统中的信道判决反馈均衡问题-Article analyzes the spectral efficiency of OFDM systems to study the OFDM system channel decision feedback equalizer problem Platform: |
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Author:王云峰 |
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Description: Abstract—In this paper we present an initial performance
evaluation of the 3GPP UTRA Long Term Evolution (UTRA
LTE) uplink with baseline settings. The performance results
are obtained from a detailed UTRA LTE uplink link level
simulator supporting OFDMA and SC-FDMA schemes. The basic
transmission scheme for uplink direction is based on singlecarrier
transmission in the form of DFT Spread OFDM with
an MMSE receiver. Two antenna configurations, SISO and 1x2
SIMO are considered in the analysis of spectral efficiency in
addition to Adaptive Modulation and Coding (AMC) and L1-
HARQ. For assessment purposes, the performance results of
SC-FDMA are compared with OFDMA. It is shown that 1x2
SIMO greatly increases the spectral efficiency of SC-FDMA
making it comparable to OFDMA, especially for high coding
rate. Furthermore, SC-FDMA has a flexibility to increase BLER
performance by exploiting frequency diversity. Platform: |
Size: 160768 |
Author:ashokec |
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Description: Iterative receiver techniques, multiple-input – multiple-output (MIMO) processing, and
orthogonal frequency division multiplexing (OFDM) are amongst the key physical layer
technologies when aiming at higher spectral efficiency for a wireless communication system.
Special focus is put on iterative detection, decoding, and channel estimation for a MIMO-OFDM
system. After designing separately efficient algorithms for the detection, channel decoding, and
channel estimation, the objective is to optimize them to work together through optimizing the
activation schedules for soft-in soft-out (SfISfO) components. Platform: |
Size: 3104768 |
Author:ashish |
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Description: Reaching Higher data rate and spectral efficiency are among the challenges expected for 4G wireless systems. Combining OFDM modulation and multiple-input multipleoutput (MIMO) help for that. In this paper, performances of a WiMAX MISO-OFDM based system are studied through
measurements done in a reverberation chamber. The used antennas’ specifications are given as well as the numerical blocks description. The results obtained are compared to a reference
case with single-input single-output (SISO) in order to evaluate the studied system’s real performances Platform: |
Size: 466944 |
Author:satish |
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Description: This M Code simulate the effects of clipping and filtering on PAPR reduction in OFDM-based wireless standard.Also the performance of BER versus SNR of original OFDM signals with PAPR reduction based on clipping and filtering schemes over AWGN channel is evaluated.
The simplest and most widely used technique of PAPR reduction is to basically clip the part of signals that are outside the allowed region.Clipping methode introduces both in band distortion and out of band radiation into OFDM signals which degrades the performance including the BER and spectral efficiency.Filtering can reduce out of band radiation after clipping although it can not reduce in-band radiation distortion.However, clipping may cause some peak regrowth so that the signal after clipping and filtering will exceed the clipping level at some point.To reduce peak regrowth a repeated filtering and clipping operation can be used to obtain a desirable PAPR at a cost of computational complexity increase.
-This M Code simulate the effects of clipping and filtering on PAPR PAPR reduction in OFDM-based wireless standard.Also the performance of BER versus SNR of original OFDM signals with PAPR reduction based on clipping and filtering schemes over AWGN channel is evaluated.
The simplest and most widely used technique of PAPR reduction is to basically clip the part of signals that are outside the allowed region.Clipping methode introduces both in band distortion and out of band radiation into OFDM signals which degrades the performance including the BER and spectral efficiency.Filtering can reduce out of band radiation after clipping although it can not reduce in-band radiation distortion.However, clipping may cause some peak regrowth so that the signal after clipping and filtering will exceed the clipping level at some point.To reduce peak regrowth a repeated filtering and clipping operation can be used to obtain a desirable PAPR at a cost of computational complexity increase.
Platform: |
Size: 11770880 |
Author:shahram |
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Description: basic ofdm with interlever:
The
transmitter section converts digital data to be transmitted, into a mapping of
subcarrier amplitude and phase. It then transforms this spectral representation of
the data into the time domain using an Inverse Discrete Fourier Transform
(IDFT).
The Inverse Fast Fourier Transform (IFFT) performs the same operations as an
IDFT, except that it is much more computational efficiency, and there is used in
all practical systems. In order to transmit the OFDM signal the calculated time
domain signal is then mixed up to the required frequency. Platform: |
Size: 2048 |
Author:asmaa |
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Description: As a multicarrier transmission system Orthogonal frequency division multiplexing (OFDM) has
been widely applied in wireless communication systems due to its numerous advantages like
robustness against multipath fading and delay, high data rate transmission capability, high
spectral efficiency, allows adaptive modulations Platform: |
Size: 120832 |
Author:archana |
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Description: Spectral Efficiency Analysis in OFDM and
OFDM/OQAM based Cognitive Radio Networks
The future wireless communication is expected to
be able to improve the efficiency of spectrum usage. To solve the challenge of spectrum shortage, an innovative opportunistic spectrum access strategy, called Cognitive Radio (CR) has been proposed. Platform: |
Size: 165888 |
Author:Honaleum |
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Description: JIOO算法，用于在下行OFDM系统中进行能量效率和频谱效率的权衡优化-JIOO algorithm used for energy efficiency and spectral efficiency tradeoff optimization in the downlink OFDM systems Platform: |
Size: 1024 |
Author:张玉洁 |
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Description: systems (GNSS) signal modulation schemes. MSK is used
in global system for mobile communications because of its
spectral efficiency, while OFDM is used in WLAN and
digital video broadcast-terrestrial because of its multipath
mitigation capability. These advantages of MSK and Platform: |
Size: 1389568 |
Author:杨松 |
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Description: Multiple Input Multiple Outputs, a wireless or radio communications technology normally used with OFDM for many wireless and radio communications. Multiple-input multiple-output, or MIMO, is a radio communications technology or RF technology that is being mentioned and used in many new technologies these days. Wi-Fi, LTE (3G long term evolution) and many other radio, wireless and RF technologies are using the new MIMO wireless technology to provide increased link capacity and spectral efficiency combined with improved link reliability using what were previously seen as interference paths. Even now many there are many MIMO wireless routers on the market, and as this RF technology is becoming more widespread, more MIMO routers and other items of wireless MIMO equipment will be seen. Platform: |
Size: 129024 |
Author:nebiyu |
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Description: Multiple Input Multiple Outputs, a wireless or radio communications technology normally used with OFDM for many wireless and radio communications. Multiple-input multiple-output, or MIMO, is a radio communications technology or RF technology that is being mentioned and used in many new technologies these days. Wi-Fi, LTE (3G long term evolution) and many other radio, wireless and RF technologies are using the new MIMO wireless technology to provide increased link capacity and spectral efficiency combined with improved link reliability using what were previously seen as interference paths. Even now many there are many MIMO wireless routers on the market, and as this RF technology is becoming more widespread, more MIMO routers and other items of wireless MIMO equipment will be seen. Platform: |
Size: 579584 |
Author:nebiyu |
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Description: Here, wavelets are used in Orthogonal frequency division multiplexing. Wavelets are small waves having amplitude increase starting zero and reduces back to zero. In conventional OFDM, IFFT is used at the transmitter side and FFT is used at receiver. In case of Wavelet OFDM, IFFT is replaced with IDWT and DWT is used instead of FFT. In OFDM cyclic prefix is added to reduce inter channel interference and inter carrier interference. By using wavelet transform, cyclic prefix is not needed. Hence, it has high spectral efficiency. Wavelet transform the signal one domain to time and frequency domain. -Here, wavelets are used in Orthogonal frequency division multiplexing. Wavelets are small waves having amplitude increase starting zero and reduces back to zero. In conventional OFDM, IFFT is used at the transmitter side and FFT is used at receiver. In case of Wavelet OFDM, IFFT is replaced with IDWT and DWT is used instead of FFT. In OFDM cyclic prefix is added to reduce inter channel interference and inter carrier interference. By using wavelet transform, cyclic prefix is not needed. Hence, it has high spectral efficiency. Wavelet transform the signal one domain to time and frequency domain. Platform: |
Size: 1024 |
Author:Salini |
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Description: Low-density parity-check (LDPC) coded optical orthogonal frequency division multiplexing (OFDM) is shown to significantly outperform other coded OFDM over the fading channel in terms of both coding gain and spectral efficiency. Platform: |
Size: 662776 |
Author:mustafa1970 |
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Search - spectral efficiency in OFDM