The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The paper deals with the estimation method of a carrier and time of arrival by chirp-like phase-coded sequence. The developed estimation method of the carrier and time of arrival is suitable for primary synchronization upon signal detection in phase and frequency modulation modems. This method is of less computational complexity relative to the realization of matched filter assembly. To implement...
The problem of carrier frequency and phase synchronization exists in most wireless digital communication systems. These offsets are generally results from the Doppler effect, oscillator instabilities, and unknown transmission delays between receiver and transmitter. In this paper, we propose a joint synchronization algorithm applicable for short-burst PSK modulation systems. In the coarse estimation,...
In this paper, we present the simulation results of FFO(fractional frequency offset) influences on PLC preamble correlation based PLC synchronization in DOCSIS 3.1 Downstream. FFO makes inter-carrier interferences and breaks orthogonality in OFDM based transmission system. It degrades the performance of OFDM by reducing SNR(signal to noise ratio). The performance of PLC synchronization is influenced...
Although the Filter bank multicarrier with offset quadrature amplitude modulation (FBMC-OQAM) systems are robust against double selective fading channels, it unfortunately is still sensitive to timing offset and carrier frequency offset (CFO) errors. To solve this synchronization problem, in this paper, we propose a new data-aided timing and CFO synchronization scheme, that exploits the conjugate-symmetry...
In this paper, we propose a comparison method of training symbol (or preamble) and Cyclic Prefix (CP) to improved the frequency synchronization in orthogonal frequency division multiplexing (OFDM). The problems that arise in OFDM system is the time-shift and frequency mismatch between the oscillators in the transmitter and the receiver. It is known as a Carrier Frequency Offset (CFO) problem. By exploring...
A low rate of signal element transmissions in a communication system and a low SNR at the receiving side results in a normalized large frequency offset. To address this problem, the paper compares the performance from the aspect of the computational complexity, stability, noise immunity, and estimation accuracy. The performance is evaluated under different carrier frequency synchronization algorithms...
In this paper, a pilot-aided frequency synchronization scheme for orthogonal frequency division multiplexing (OFDM) systems is proposed. A maximum likelihood (ML) estimator based on Double Dwell Synchronization (DDS) is employed for offset estimation and correction. The proposed DDS scheme provides an accurate estimate over a wide estimation range with reduced computational complexity for both AWGN...
In the IEEE 1588 Precision Time Protocol (PTP), the recovery of clock frequency and phase from packet timestamps must be modeled as a statistical estimation problem, due to the random nature of end-to-end delays that is inherent to packet-switched networks. Recently, a new minimax optimum estimator for phase offset estimation was proposed by the authors. This approach assumes that perfect frequency...
Traditional algorithms of HF burst signal detection and synchronization acquisition usually can't work well under low signal noise ratio (SNR). Aiming at the character of HF channel, a reliable synchronization acquisition scheme for HF channels based on spectrum analysis method was obtained by modulated m-sequences pilots to get some dispreading gains. The integer and fractional frequency shift can...
In an OFDM-based cooperative relay system, the arrival times and carrier frequency offsets (CFOs) of the signals from different relays are most likely different. Estimation of these timing offsets and CFOs is a crucial and challenging task. In this paper, a new preamble structure is designed, and an efficient time and frequency offset estimator is proposed for the OFDM-based cooperative system. The...
Multi-hop networks have been proposed as a new type of autonomous networks recently. Various multi-hop routings employ flooding mechanisms, where all terminals retransmit a same packet to a whole network to distribute information. It is well known that flooding mechanisms consume a lot of wireless resources. Additionally, broadcast storm problems occur when a number of nodes or traffic increase in...
In this paper, a novel joint time-frequency synchronization algorithm was developed for orthogonal frequency division multiplexing systems based on fraction Fourier transform (FrFT-OFDM) in multipath fading channel. It can eliminate the ambiguity of the first arriving path estimation in multipath channels. And the digital synchronization structure implementation based on the proposed algorithm for...
In this paper, we investigate the synchronization for OFDMA-based wireless mesh networks and analyze the effect of carrier frequency misalignment between distributed nodes. Based on our previous work, so called, Distributed Frequency Synchronization (DFS), we propose a modified DFS (mDFS). The proposed scheme incorporates some practical issues, not considered in the previous DFS scheme. Simulation...
Synchronization in Orthogonal Frequency Division Multiplexing (OFDM) based systems, is a primordial task due to the sensitivity to symbol timing and carrier frequency offset of OFDM. There are two ways to synchronize the air access in wireless systems: unframed (packet based) and framed transmission. Both of them are based on well designed sequences, with a low Peak Average to Power Ratio (PAPR),...
Orthogonal Frequency Division Multiplexing (OFDM) is a promising technology for combating the frequency selective fading, multipath propagation, and narrowband interference in power line communication. However, OFDM systems are extremely sensitive to synchronization deviation. Slight synchronization deviation can affect the performance of OFDM systems. This paper presents a design and implementation...
In order to estimate frequency offset accurately in the process of downlink synchronization, a new fraction frequency offset estimation algorithm is derived for TD-LTE system. The proposed algorithm utilized the time-domain symmetry character of primary synchronization signal (PSS) to estimate normalized fraction frequency offset. Compared to the conventional algorithms, it can estimate fraction frequency...
In order to reduce the influences of synchronization signals in CMMB (China Mobile Multimedia Broadcasting) system, which caused by multipath and frequency offset in wireless channel. This paper combined the specific frame structure of CMMB standard protocol, analyzed some influences for symbol synchronization, and proposed a coarse symbol timing synchronization algorithm that was based on traditional...
In this paper, an improved algorithm of coarse synchronization in the downlink of 3GPP LTE system is presented. This new algorithm can reduce the MSE (mean square error) of detected fractional carrier frequency offset (FCFO) by an order of magnitude and improve the accuracy rate of start point estimation by near 80 percent when SNR equals 0 in contrast with conventional coarse synchronization algorithms,...
In this paper we propose a reduced-complexity two-stage time and frequency synchronization approach for OFDM systems, operating in multipath channels. The proposed approach exploits a single-symbol preamble with a repetitive structure, composed of two identical m-sequences. The first coarse stage, based on a sliding correlation, finds out the reduced uncertainty interval over which the second fine...
Frequency offset estimation is an important issue in digital transceiver design, especially for coherent wireless transmission such as in WiMAX systems based on the IEEE 802.16e orthogonal frequency-division multiple access (OFDMA). The downlink synchronization, in WiMAX systems, involves synchronization of carrier frequency and timing as well as identification of the preamble index. This paper introduces...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.