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For the unlicensed spectrum, the occupied bandwidth requirement is demanded by some regulations. The legacy scheme of Physical Random Access Channel (PRACH) for Long Term Evolution (LTE) cannot satisfy it. In this paper, we propose a novel PRACH transmission scheme to satisfy the requirement of unlicensed spectrum based on preamble pairing, and show some other candidates. We analyze and evaluate the...
A minimum mean square error estimation (MMSE) using a virtual pilot channel estimation scheme was proposed by our researchers for improving the error performance of the IEEE 802.11p. However, compared to the STA channel estimation scheme, the MMSE scheme cannot provide an acceptable error performance in a low SNR region. To alleviate this, we propose an adaptive channel estimation scheme, which selectively...
This paper presents a vehicle positioning method based on joint estimation of time of arrival (TOA) and direction of arrival (DOA) with Vehicle-to-Roadside (V2R) communications. By analyzing the measured channel frequency response (CFR) between vehicles and the roadside unit (RU), the enhanced two-dimensional matrix pencil (2-D MP) algorithm is implemented to design the parameter estimator, which...
One of the orthogonal frequency division multiplexing (OFDM) schemes is the Time Domain Synchronous OFDM (TDS-OFDM) scheme, in which, the guard intervals between consecutive OFDM symbols contain Pseudo Noise (PN) sequences which are known to the receiver and are used for channel estimation and synchronization. In this paper, a joint channel estimation algorithm is proposed for TDS-OFDM scheme, the...
A novel method for distance estimation is introduced, based on an OFDM signal combined with the Zadoff-Chu Sequences. By exploiting the properties of these sequences it is possible to evaluate the distance between a transmitter and a receiver with a very good precision and accuracy. The technique effectiveness is demonstrated in a real operating environment by measuring the distance between two active...
Doubly selective channels or time-varying multipath channels occur when communication systems are expected to work in a highly mobile environment. The estimation and the subsequent equalization of such channels is a non-trivial task. Thus, a channel estimation scheme that is robust, precise and works with a complexity that is applicable for consumer applications is vital to overcome the effects of...
This article discusses the problems of time shift estimation in passive radar systems, radio monitoring systems, also in measuring and control equipment. Existing methods of time shift estimation are considered. A new method to improve the accuracy of estimation of the time shift is proposed. Simulation of the known methods and the proposed method produced. The effectiveness of the proposed method...
In this paper, we propose a tracking mechanism for the residual sampling clocking offset (SCO) with corresponding pilot and auxiliary pilot arrangements for filter bank multi-carrier (FBMC) offset QAM (OQAM) baseband receiver in the 60 GHz band. This work can effectively compensate the non-ideal effects on the high-band subcarriers while using more data subcarrier for increasing bandwidth efficiency...
This paper presents a computationally efficient cyclostationarity detection based spectrum sensing in cognitive radio. Traditionally, several cyclostationarity detection based spectrum sensing techniques with a low computational complexity have been presented, e.g., peak detector (PD) or maximum cyclic autocorrelation selection (MCAS), and so on. Compared to both techniques, PD can be affected the...
In this paper, a novel pilot-aided algorithm is proposed for the detection of integer frequency offset (IFO) in orthogonal frequency division multiplexing (OFDM) systems. By transforming the IFO into two new integer parameters, the proposed method can largely reduce the number of trial values for the true IFO. The two new integer parameters are detected using two different pilot sequences, a periodic...
This paper presents a novel super-resolution time of arrive (TOA) estimation algorithm, which utilizes the primary synchronization signal (PSS) in LTE downlink. Unlike the conventional coherent detection algorithm with sample-level estimation accuracy, the proposed algorithm fully takes advantage of phase characteristic of the sampled orthogonal frequency division multiplexing (OFDM) signal to reach...
Emerging cellular networks integrate the user terminal geo-localization function besides the communication function. The conventional positioning approach is to estimate the terminal location in two-steps: first the distance to all connected base stations is assessed based on signal time-of-flight measurements, then the location is deduced from the distances by multi-lateration. The two-step approach...
In LTE-Advanced (LTE-A) demodulation reference symbols are employed for pilot aided channel estimation to perform coherent detection. Since these reference symbols are allocated on the same time-frequency positions for all users in Multi-User MIMO (MU-MIMO) operation or for all spatial layers in Single-User MIMO (SU-MIMO), they are designed to be code-domain orthogonal in order to be separable at...
A new method of applying EMD (empirical mode decomposition) algorithm to realize the CFO (carrier frequency offset) estimation of single channel OFDM (orthogonal frequency division multiplexing) system is proposed in this paper. Firstly, the observation signal is extracted by using correlation detection technology to process the received OFDM signal. Then the data with CFO information is obtained...
This paper deals with simple and effective residual carrier frequency offsets (CFO) estimation approaches for interleaved orthogonal frequency division multiple access (OFDMA) uplink systems. It has been shown that the propagator method (PM) has low computational load and is efficient in noise free environments. However, the PM is not robust to noise. With the forward-backward (FB) correlation matrix...
In this paper, we present a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) based backhaul link in the presence of hardware impairments, such as phase noise (PN), residual carrier frequency offset (RCFO), and sampling frequency offset (SFO). Focusing on these adverse hardware effects on the MIMO-OFDM system, we propose corresponding signal processing algorithms...
With the rapid deployment of the high speed railway (HSR), the wireless communication in HSR has been one of the indispensable scenarios in the fifth generation (5G) communications. In order to improve the performance of the orthogonal frequency division multiplexing (OFDM) system in the HSR scenarios, we propose an enhanced linear minimum mean square error channel estimation scheme based on multi-path...
In this paper a simple algorithm for the estimation of the Direct Path (DP) Time of Arrival (TOA) in an OFDM-based telecommunications system is proposed. It is shown that, under certain conditions, it is possible to infer the TOA of the direct path by estimating the phase slope across the subcarriers. The proposed algorithm exploits the intrinsic properties of a multi-carrier OFDM system to perform...
The estimation of the noise power is a core issue in wireless communication systems. In broadcasting, every OFDM frame starts with a preamble symbol, which facilitates the noise power estimation. However, the performance of preamble-based noise estimation schemes worsens in fast-changing environments and cannot efficiently track the noise variation well. In order to track the noise variation symbol...
This work addresses the problems of frequency synchronization and channel estimation for OFDM/OQAM systems in Rayleigh fading channel. A two-step preamble based approach using a new frame structure is proposed. The first step is coarse carrier frequency offset (CFO) estimation and the second step is joint fine CFO (FCFO) and channel estimation. We also propose a FCFO estimator under the assumption...
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