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Nowadays many logging communication systems adapt the Orthogonal Frequency Division Multiplexing (OFDM) for the implementation of high transmission rate. In order to realize higher rate, adaptive bit allocation is proposed, which is based on signal-to-noise ratio (SNR). SNR is a significant evaluation parameter for the channel quality in the communication systems. In this paper, we derive a SNR estimation...
Channel estimation is an important issue in orthogonal frequency division multiplexing (OFDM) systems to improve the performance of system. For OFDM based IEEE 802.11ad wireless local area network (WLAN), two types of symbols, training symbols and pilot symbols, can be used for channel estimation in the OFDM receiver. We analyze the algorithms of channel estimation methods based on symbol types, training...
Localization, a process of determining the position of a blind node, can be used in various applications. Signal-strength localization provides a low-cost and lowpower solution to positioning. Signal-strength positioning approaches using fingerprinting or calibrated approaches require a time-consuming calibration phase. Existing selfcalibrating approaches, which do not require a priori calibration,...
Many wideband wireless propagation media, including millimeter-wave and underwater acoustic channels, exhibit sparse impulse responses. Exploiting the sparse character of such channels using compressed sensing techniques can potentially lead to substantial savings in pilot overhead. In this paper, we address sequential Bayesian estimation of sparse/compressible channels with a Kalman tracking filter...
Many wireless communication media (e.g., underwater acoustic and mm-wave radio channels) exhibit sparse impulse responses that can be exploited at the receiver using compressed sensing methods in order to reduce the pilot overhead required for channel estimation. The success of sparse recovery methods, however, heavily depends on whether the received samples admit an exactly sparse representation...
The single-carrier frequency-division multiple access (SC-FDMA) or the discrete Fourier transform (DFT) pre-coded orthogonal frequency-division multiple access (OFDMA) technique has been adopted in the uplink transmission of the long term evolution (LTE) terrestrial communication standard, for its lower peak-to-average power ratio (PAPR) and similar receiver complexity, compared with OFDM. It is,...
Accurate and efficient channel estimation methods have the ability to realize the theoretical gain in multi-input multi-output (Massive MIMO) systems which have a massive number of antennas. However, the pilot contamination in Massive MIMO channel estimation process, rooted from the pilot reuse, is a critical problem that severely degrades the performance of the system. This work aims to address the...
The present work offers the solution for a target speed estimation in two dimensional space by the distributed radar systems. The proposed method supposes initial separated estimation of speeds in all channels (as it is done in conventional systems) and further refined estimation of the target speed by the joined least squares optimization. It was shown that the refined estimation allows obtaining...
Inter-vehicular communication is a major research field in the intelligent transportation systems (ITS) industry. It has been increasingly growing due to recent advances in mobile and wireless communication technologies. This paper aims to present a novel cross layer channel estimation technique for inter-vehicular communication based on Bayesian network theory. It proposes a multi-criteria estimation...
Filter bank multi-carrier with offset QAM(FBMC/OQAM) is a multi-carrier modulation technique that can be an alternative to conventional orthogonal frequency division multiplexing(OFDM) with cyclic prefix (CP) in wireless network. FBMC has a higher spectrum efficiency and effective emission power without CP. Because the orthogonality only exists in real domain, the channel estimation in FBMC/OQAM system...
In multichannel systems, acoustic time delay estimation (TDE) is a challenging problem in reverberant environments. Although blind system identification (BSI) based methods have been proposed which utilize a realistic signal model for the room impulse response (RIR), their TDE performance depends strongly on that of the BSI, which is often inaccurate in practice when the identified responses are under-modelled...
Knowledge of interacting channels is essential for characterizing the performance of a cognitive radio system in terms of interference power received by a primary receiver and throughput at a secondary receiver. Baseline models considered for the performance characterization assume perfect knowledge of the interacting channels. Recently, an analytical framework has been proposed that incorporates...
In this paper we present a decision feedback channel estimation way for the mobile satellite communication system in order to improve the bit error performance. The transmission is disturbed not only by shadowing and multipath effects and additive white Gaussian noise, but also by the weather attenuation. The conventional Least Square(LS) is not well suited to detect the transmitter sequence, whereas...
Visible light communication (VLC) has been a research hotspot for broad bandwidth, high speed, and anti-interference. Power line communication (PLC) has the advantages of low cost and flexible access, which is connected and combined with VLC to be a hybrid communication system. We set up a communication system model of PLC&VLC based on orthogonal frequency division multiplexing (OFDM) modulation,...
This paper presents the use of recursive least squares for online estimation of the self interference channel for an In Band Full Duplex communications link without the use of half duplex pilot signals. By using a long effective filter length it is possible to overcome the extra interference of the receieved signal, and it proves to be an effective way to estimate the channel in all scenarios, but...
Estimation of carrier frequency offset (CFO) is a challenging task in practical systems specifically in the uplink of multiuser systems where multiple CFOs are present in the received signal. Massive MIMO as a multiuser technique has recently attracted a great deal of attention among researchers. However, to the best of our knowledge, there is no study looking into the joint estimation of CFOs and...
Orthogonal frequency division multiplexing (OFDM) technique, with a broad usage in recent communication technologies, provides a good performance that is mostly appropriate for target quality of service levels. Yet, it will not be effective for future requirements due to its synchronization and spectral efficiency related communication system drawbacks. To address these issues, universal filtered...
The 5G network prospect of seamlessly connected global devices with delay-tolerant communication, millisecond latency and gigabits per second data rate suggests the need for high resolution location-aware systems with new methods for positioning services. Traditional geo-positioning methods have been characterized by detection and mitigation of NLOS paths where discrimination between LOS and NLOS...
In this paper, we restore images degraded by scattering and absorption such as hazy, sandstorm, and underwater images. By calculating the difference between the observed intensity and the ambient light in a degraded image scene, which we call the scene ambient light differential, we estimate the transmission map. In the restoration process, we first enhance the degraded images based on the proposed...
Haze removal, which is also referred to as image dehazing, has been extensively used to improve the visibility in images captured under inclement weather. In particular, the dark channel prior (DCP)-based single image dehazing has received the greatest amount of interest due to its superior performance. However, since the DCP is based on the characteristics of natural outdoor images, its reliability...
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