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The paper introduces an OFDM signal detector based on cyclic correlation function. The detector belongs to the class of blind SCD detectors. The paper presents the main relations connected with the idea of cyclostationarity and cyclostationary features of OFDM signals. Results of simulations are presented as well.
Discrete Fourier transform spread orthogonal frequency division multiplexing (DFTs-OFDM) has recently attacked much interest in research and developments on wireless communication systems. The combination of direct sequence code division multiple access (DS-CDMA) and DFTs-OFDM potentially offers the degradation of bit error rate (BER) performance as indicated in literatures. This paper presents the...
In this paper, we utilize the minimum mean squared error (MMSE) prediction to compensate imperfect channel reciprocity in achieving physical-layer confidentiality enhancement, particularly for our recently developed secure OFDM system with dynamic subcarrier coordinate interleaving [1]. In the proposed method, the transmitter first estimates the correlation coefficient between the forward and backward...
In this paper, we propose a timing synchronization method for orthogonal frequency division multiplexing (OFDM) systems by exploiting the averaged differential correlations of preamble symbol. For the designed simple preamble whose second half-symbol is the complex conjugate of the first one in the time-domain, the proposed timing synchronization method has an impulse-shaped timing metric. Simulation...
With the explosive development in Internet of Things (IoT) and Internet of Vehicles (IoV) technologies, massive connections with sporadic transmission will commonly exist in the future communication network. Upon that, compressive sensing based multi-user detection (CS-MUD) technique was proposed in previous works. However, CS-MUD has not been considered in high mobility scenario which will be widely...
This paper presents a possible utilization of Two-Dimensional Comlete Complenetary Codes (2D OCCC) in radar technologies. The aim is to evaluate the ambiguity function and cross-ambiguity function of phase modulated signals based on the second family of 2D OCCC. Signal is generated by modulation technique known as Orthogonal Frequency Division Multiplexing (OFDM). Complementarity of the codes is achieved...
In rate-adaptive orthogonal frequency division multiplexing (OFDM) systems, limited feedback schemes are essential to reduce the number of subchannels for which the channel state information is fed back by the users. For the practically important best-M scheme, in which each user feeds back only its M strongest subchannels and their indices to the base station (BS), we derive a throughput-optimal...
We survey our constructions of pseudo random sequences (binary, , ...) from Galois rings. Techniques include a local Weil bound for character sums, and several kinds of Fourier transform. Applications range from cryptography (boolean functions, key generation), to communications (multi-code CDMA), to signal processing (PAPR reduction).
The advancement in 4G technology mainly depends upon the Orthogonal Frequency Division Multiplexing (OFDM) scheme. OFDM scheme has much betterment like efficient spectrum usage, mitigation of selective fading effects, reduces ICI and ISI, etc. The major disadvantage of this scheme is a high peak to average power ratio (PAPR) which requires a costlier high power amplifier for processing. Partial Transmit...
Orthogonal Frequency Division Multiplexing (OFDM) is a advance bandwidth efficient digital modulation technique highly adopted for the broadband wireless services because it gives high performance in the multipath fading environments. It is very robust against narrowband interference, but it is not totally free from drawbacks. There are timing and frequency synchronization error for which this technique...
The main features for future Machine Type Communication (MTC) cellular networks enable low-power, low-cost, narrow band, and extended coverage system. To support these features, new challenges for the system design have emerged. For instance, the device shall be able to setup a call at a signal to noise ratio (SNR) of −15dB in the extended coverage mode with only one receive antenna and almost no...
In this paper a novel low complexity scheme that achieves also reduced feedback overhead is studied for reporting the channel state information in Carrier aggregation MIMO systems. Such systems usually involve a large number of carriers and users, so the calculation and reporting of the required RI/PMI/CQI indexes could result in high computational complexity and feedback overhead. Given that the...
Given that L-band digital aeronautical communications system type 1 (LDACS1) may share the same spectrum with the legacy Distance Measuring Equipment (DME) system, DME, impulsive interference would be the main issue of this aeronautical communications system. To improve the performance of the LDACS1, a time-domain Correlative Interference Mitigation (CIM) aiming at DME impulse is proposed in this...
Space-Frequency block codes (SFBC) and lattice-reduction (LR) aided linear receivers are proposed for next generation wireless communication system. Both techniques are well known and extensively studied. In this paper, we analyze the performance of the Alamouti SFBC over correlated channel and LR-aided receiver in terms of the probability of error. Lower and upper bounds on the probability of error...
Owing to the growing demand for the high-speed wireless communications which uses Orthogonal Frequency Division Multiplexing (OFDM), there is a need to provide high-quality to overcome various channel impairments appearing over the transmission link. One of the main problems in providing such mechanisms is Doppler shift. which reduces the spectral efficiency of the system, raising a need to determine...
High data rate wireless communication system introduces the unavoidable inter symbol interference (ISI), for which orthogonal frequency division multiplexing (OFDM) gives a best solution by utilizing the property of orthogonality among the sub carriers. In addition, estimating the channel characteristics under non-linear time varying random channel environment, is always a tough task for a successful...
To solve the signal separation problem in the integration system of radar and communication, a signal model based on random stepped frequency Orthogonal Frequency Division Multiplexing(OFDM) radar pulses is proposed, where the communication data is modulated on the radar pulses. The target range image can be acquired from the correlation of the echo and the reference signal, while the communication...
Quality of detection systems using matching Altering particularly depends on signals correlation characteristics. Resolution, maximum range and noise characteristic of radar based on such characteristics of correlation function as main lobe width, main lobe level and side-lobe level. It is necessary to research the influence of receiver non-linear amplifier mode to BPSK signal correlation characteristics...
In communications, a spread-spectrum sequence can be used for frame synchronization in order to detect the packets arrival. This sequence is usually detected by means of a matched filter with the original code, which ideally provides a distinguishable peak among the correlation noise. The detection of this peak is crucial, since the information contained in the data packet will be lost if the peak...
Interleaving is a process of making a system efficient by arranging its data in a noncontiguous manner. It is mostly used in wireless communication and storage systems in addition to forward error correcting codes thus enhancing their performance. The quality of digitally transmitted data over the radio fading channel is improved by this process. As every other process, interleaving has its own drawbacks...
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