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- Blind Carrier Frequency Offset Estimation in SISO, MIMO, and Multiuser OFDM Systems
- Relying on a kurtosis-type criterion, a low-complexity blind carrier frequency offset CFO estimator is developed for orthogonal frequency-division multiplexing OFDM systems. The paper demonstrates analytically how identifiability and performance of this blind CFO estimator depend on the channel's frequency selectivity and the input distribution. The paper shows that this approach...
- Tags: MIMO, OFDM, Wireless
- White papers 2005-01-01
- Delay Spread and Time Dispersion Estimation for Adaptive OFDM Systems
- Time dispersion is one of the most important characteristics of the wireless channel. The knowledge about the time dispersion of a channel can be used for designing better systems which can adapt themselves to the changing nature of the transmission medium. In this paper, algorithms for estimating the time dispersion...
- Tags: Channel, Dispersion, OFDM, Engineering, Digital Rights Management (DRM), Wi-Fi, Wireless, Security
- White papers 2006-01-22
- BER Performance of OFDM System in Frequency-Selective Rician Fading With Diversity Reception
- This paper theoretically studies the Bit Error Rate BER performance of OFDM systems with MDPSK modulation for subchannels in frequency-selective flat Rician fading and Additive White Gaussian Noise AWGN. Both the Rayleigh and Rician fading conditions are considered. The differential detection technique is used to avoid the need of a...
- Tags: Performance, Singapore, Detection Technique, OFDM, Performance Management, Wireless, Human Resources, Workforce Management
- White papers
- PAPR Reduction in OFDM Systems Using Constellation Shaping
- Orthogonal Frequency Division Multiplexing OFDM is a multicarrier transmission technique, which is widely adopted in different communication applications. OFDM prevents Inter Symbol Interference ISI by inserting a guard interval and mitigates the frequency selectivity of a multi-path channel by using a simple equalizer. This simplifies the design of the receiver...
- Tags: OFDM, Wireless
- White papers
- Pilot-Tone Based ZP-OFDM Demodulation for an Underwater Acoustic Channel
- Existing coherent underwater acoustic communication systems rely on single carrier transmission and adaptive decision feedback equalization to deal with time-varying and highly dispersive UnderWater Acoustic UWA channels. Equalization complexity prevents any substantial rate improvement with the existing single-carrier approach, as the channel frequency selectivity increases considerably when the symbol rate...
- Tags: Channel, Equalization Complexity, OFDM, Wireless
- White papers 2006-07-26
- System Design Considerations for High Data Rate Communications Over Multi-Wire Overhead Power-Lines
- Broadband power-line communications over multi-wire overheard lines using Orthogonal Frequency Division Multiplexing OFDM is considered in this paper. From earlier investigations, it is known that this channel suffers with multipath fading and frequency selectivity. Nevertheless, the calculated channel capacity limit promises very high data rates over this channel, subject to...
- Tags: Pennsylvania State University, Powerline, OFDM, Wireless
- White papers 2005-07-01
- Performance Degradation of OFDM Systems Due to Doppler Spreading
- The focus of this paper is on the performance of Orthogonal Frequency Division Multiplexing OFDM signals in mobile radio applications, such as 802.11a and Digital Video Broadcasting DVB systems, e.g., DVB-CS2. The paper considers the evaluation of the error probability of an OFDM system transmitting over channels characterized by frequency...
- Tags: Performance, OFDM, Wireless
- White papers 2006-06-01
- Bluetooth Operation
- The networking standards of Bluetooth will transmit data via low power radio frequency. Bluetooth communicates on a 2.45 GHz frequency. This very band of frequency has been set aside by international agreement for the use of industrial and medical devices. Many devices that one already known and use take advantage...
- Tags: Frequency, Bluetooth, Wi-Fi, Wireless
- White papers
- Computer Simulation of Interactions Responsible for Length and Width Tuning in the Striate Cortex
- This paper describes a simulation of the long-range inhibitory interactions that produce end-stopping, surround-stopping and side-stopping in the primary visual cortex. Unlike previous models, but in line with recent understanding, the approach used here incorporates a divisive rather than a subtractive influence from the receptive field surround, and includes phase...
- Tags: Length, Computer, Productivity
- White papers 2005-11-17
- Frequency Counter (zip)
- Frequency Counter is an easy to use utility to assist with classical cryptanalysis. It takes a text file, up to 2G, and computes the frequency of characters A-Z. Results are displayed numerically and graphically. Great for students of cryptology.
- Tags: Frequency, Frequency Counter, Cellular Phones, Consumer Electronics, Personal Technology
- Software downloads 2005-09-14
- Noncoherent Space-Frequency Coded MIMO-OFDM
- Recently, the use of coherent space-frequency coding in orthogonal frequency division multiplexing OFDM-based frequency-selective multiple-input multiple-output MIMO antenna fading channels has been proposed. Acquiring knowledge of the fading coefficients in a MIMO channel is already very challenging in the frequency-flat fast fading case. In the frequency-selective case, this task becomes...
- Tags: Channel, MIMO, IEEE, MIMO-OFDM, OFDM, Wireless
- White papers 2005-02-14
- Space-Frequency Bit-Interleaved Coded Modulation for MIMO-OFDM
- This paper presents the design of a novel space-frequency bit-interleaver for MIMO-OFDM systems. The proposed Space-Frequency Interleaver SFI interleaves convolutionally coded bits across transmit antennas and frequency tones. Performance is analyzed for a simplified channel model and is demonstrated for a modeled IEEE 802.16e OFDM PHY layer using ITU channel...
- Tags: Performance, Stanford University, MIMO-OFDM, Space-frequency Interleaver, OFDM, Wireless
- White papers 2005-11-02
- Joint Time-Domain Tracking of Channel and Frequency Offset for OFDM Systems
- This paper addresses the problem of joint channel and frequency offset estimation and tracking for OFDM systems. The proposed method is based on Extended Kalman filtering. The channel taps and the frequency offset are estimated in time-domain while equalization is performed in frequency domain. Simulation results demonstrate accurate tracking capability...
- Tags: Frequency, Channel, Method, OFDM, Wireless
- White papers 2006-03-21
- Experimental Studies on a OFDM Carrier Frequency Offset Estimator
- In OFDM carrier frequency offset must be estimated and compensated at the receiver to maintain orthogonality. OFDM carrier frequency synchronization performance can be improved by using diversity. This paper examines the sensitivity of the carrier frequency estimator against key system parameters in a practical implementation using real data obtained on...
- Tags: OFDM, Wireless
- White papers
- An Interpolation-Based Frequency-Synchronization Scheme for OFDM Systems
- The mismatch of the oscillators in the transmitter and receiver, or Doppler shift, introduces an offset in the expected carrier frequency. In orthogonal frequency-division multiplexing OFDM systems, this frequency offset causes large errors in the signal values and therefore it is important to minimize this offset. This paper proposes an...
- Tags: Helsinki University, Offset, OFDM, Wireless
- White papers 2005-04-28
- Multiuser Interference Cancellation for OFDM Systems With Frequency Offset
- This paper proposes a method to counteract the effect of different frequency offsets of the users in a OFDMA uplink system with frequency selective Rayleigh fading channel. The multiple access interference is reduced by reconstructing and removing the interfering signals. This is done by accomplish Successive or Selective Cancellation. The...
- Tags: Frequency, Access Interference, OFDM, Wireless
- White papers 2003-07-15
- A Blind Frequency Offset Estimator for OFDM/OQAM Systems
- Like other OFDM-like systems, OFDM/OQAM systems are very sensitive to carrier frequency offset. A new blind carrier frequency estimator is introduced herein for OFDM- /OQAM systems by exploiting the non-circularity of the received signal. Since the received signal exhibits conjugate cyclic frequencies at twice the carrier frequency offset, a frequency...
- Tags: Frequency, Texas A&M University, OFDM, Wireless
- White papers
- Performance of an Adaptive Multiuser OFDM Uplink With Carrier Frequency Offsets
- Using an OFDM based uplink for the future cellular network has been controversial issue due to difficulties in time and frequency synchronization and high Peak-to-Average Power Ratio PAPR. In this paper, a model is provided to quantify the effects of carrier frequency offsets in a multiuser OFDM uplink. The paper...
- Tags: Performance, Carrier Frequency Offset, Frequency Division Duplex, OFDM, Wireless
- White papers
- Joint Channel and Frequency Offset Estimation for OFDM Systems
- In this paper, a joint channel and frequency o set estimation algorithm is proposed. The time variation of the effective Channel Impulse Response CIR due to frequency o set is tracked using a channel tracker. This variation is used to estimate the frequency o set as well as the actual...
- Tags: Algorithm, Frequency, OFDM, Engineering, Productivity, Wireless
- White papers
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