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In this paper, we present the baseband receiver design for IEEE 802.11ah. We study several key receiver algorithms, including coarse frequency offset estimation and coarse timing synchronization, fine frequency offset estimation, fine timing synchronization, channel estimation and MIMO equalization. For channel estimation, we propose to use decoded SIG field to improve its estimation. To further improve...
In this paper, we propose an efficient preamble structure for improving the timing synchronization in Multiple Input Multiple Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) systems. The proposed short preamble symbol consists of four equal duration sub symbols, the first and third of which are CAZAC sequences. The second sub symbol is comprised of PN sequences. The fourth sub symbol...
IEEE 802.11p is a new standard to support intelligent transport system (ITS) applications which is an approved amendment to the IEEE 802.11a standard to add wireless access in vehicular environments. Timing synchronization is studied a lot for IEEE 802.11a, but for IEEE 802.11p, there is few literature. Therefore, a new method is put forward and the characteristics of the timing synchronization samples...
In underwater acoustic communications, Doppler effect should be described by Doppler scale which adversely affects the performance of the communication system. This paper presents a method by employing the hyperbolic frequency modulation (HFM) signal as a channel probe to make Doppler estimation and timing synchronization simultaneously. The Doppler compensation is realized by linear interpolation...
A new preamble structure is proposed for Narrowband Power Line Communication (NB-PLC) system, and therefore a corresponding timing estimator with interval detection and pattern matching is put forward. In the new estimator, firstly the received signals are conducted cross-correlation with the preamble in the transmitter, then the cross-correlation values are obtained and divided into several groups...
In order to obtain the best possible time instant for the start of received frame, in this paper, we concentrate on designing an effective timing synchronization algorithm based on a modified training sequence for the MIMO-OFDM systems. Firstly, the framework of MIMO-OFDM system with synchronization is illustrated, which is made up of the sender module and the receiver module. Secondly, the formal...
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 this paper, a simple and effective synchronization scheme for NC-OFDM systems is proposed. To keep the autocorrelation in the scenario of subcarriers deficiency, the preamble is consists of two identical pseudo-noise (PN) sequences instead of ZC sequences. Coarse timing estimation and fractional CFO(carrier frequency offset) estimation are completed according to the correlation between the received...
A new training symbol with special structure is proposed aimed at the synchronization problem of orthogonal frequency division multiplexing (OFDM). Being different from many classical algorithm, the training symbol has special phase rotation relationship in the frequency domain. Based on this structure, a new joint symbol timing and frequency synchronization algorithm is presented. In the New algorithm,...
In orthogonal frequency division multiple access (OFDMA) uplink system, estimations of time delay and carrier frequency offset (CFO) are both particularly challenging. In this paper, a coarse CFO and time delay estimation method is proposed for interleaved OFDMA uplink system. By exploiting the special scheme of interleaved OFDMA, the repetitive time-domain training symbol is designed, and the training...
This paper studies the frame synchronization of Orthogonal Frequency Division Multiple Access-Time Division Duplexing (OFDMA-TDD) systems and proposes a new method for downlink of IEEE 802.16 to improve frame synchronization performance. In this paper, we adapt three existing timing metrics for frame synchronization in OFDM mode of WiMAX. Among the methods considered, it is shown that direct application...
Timing and frequency synchronization are the important task in receiver. In this paper, an efficient timing and carrier frequency offset (CFO) estimation method for orthogonal frequency division multiple access/ time division duplexing (OFDMA/TDD) mode in IEEE 802.16-2004 standard (WiMAX) is represented. This method has high performance and jointly estimates timing error and CFO. The performance is...
Timing and frequency synchronization is the important task in receiver. In this paper, an efficient timing and carrier frequency offset (CFO) estimation algorithm for orthogonal frequency division multiple access/ time division duplexing (OFDMA/TDD) mode in IEEE 802.16-2004 standard (WiMAX) is represented. This method has high performance and jointly estimates timing error and CFO. The performance...
The correlation-based method is the popular solution for timing synchronization. The performance of this method is decreased in low signal-to-noise ratio (SNR) because of the limited correlation peaks. In this paper, a new method based on more peaks by using a new structure of the short preamble is proposed. Simulation results show that the proposed approach greatly improves the estimation accuracy...
In orthogonal frequency division multiplexing (OFDM) system, synchronization and channel estimation are two important issues under the wireless fading channel in broadband wireless communication. The timing and frequency offset will affect the accuracy of channel estimation. These issues are studied in this paper, and a frequency selective fading channel under the OFDM system model is set up. This...
Monitoring of industrial and community environments and infrastructures are increasing targets for wireless sensor network (WSN) applications. Such applications are distributed by their nature and require essentially timing synchronization and location awareness of the sensor nodes. In this paper we present a WSN platform suitable for environment and condition monitoring applications. Time synchronization...
In the cooperative relay system, different frames from different relays are not aligned in the time domain, and have different carrier frequency offsets (CFOs). Estimation of these time offsets and multiple CFOs is a crucial and challenging task. In this contribution, a new preamble structure is proposed, and the corresponding timing and frequency synchronization algorithms are also presented for...
According to the feature of underwater acoustic channel (UWA), the implementation of time and frequency synchronization is introduced. In the sea area, the experiment result show that the synchronization method of OFDM system has the better performance.
In this paper, a complete solution to the initial synchronization for multi-cell OFDMA (orthogonal frequency division multiple access) systems is proposed. The proposed method consists of the following operations: timing synchronization, fractional carrier frequency offset (CFO) estimation, fractional CFO compensation, and joint integer CFO and preamble index estimation. To estimate multiple fractional...
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