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A novel method of single channel speaker segregation using the group delay cross correlation function is proposed in this paper. The group delay function, which is the negative derivative of the phase spectrum, yields robust spectral estimates. Hence the group delay spectral estimates are first computed over frequency sub-bands after passing the speech signal through a bank of filters. The filter...
We precisely measure the time-energy correlation of broadband, spontaneously generated four waves mixing, and demonstrate surprising intensity dependent splitting of the correlation in both time and frequency and coupling effects between the domains.
In this paper, the nonstationary statistical analysis of data obtained from mobile channel measurement campaign in a suburban environment is presented. The analysis is based on the non-WSSUS concept where the region of stationarity is defined. This region is defined bearing in mind that the interval over which WSSUS can be assumed is limited and dependent on the properties of the transmit signal and...
The innovative spreading codes used to modulate the new Galileo signals creates new challenges for receiver designers. It is well known in GNSS systems that longer integration times are needed to obtain a better sensitivity. However, the existence of the new tiered code concept that consists of the presence of a secondary code on top of the primary code to modulate the RF signal puts a limitation...
The uncoded performance of an Alamouti space-frequency block code operating in a frequency-selective channel is studied in the presence of channel estimation errors. The Alamouti Maximum Likelihood (ML) symbol detector with linear combining is considered at the receiver. Imperfect channel estimates are provided by a realistic Wiener interpolator. The impact of channel estimation errors and correlation...
The design and deployment of efficient vehicle-to-vehicle (V2V) communications systems require the knowledge of the propagation channel in which it will operate. Due to the mobility of the transmitter/receiver terminals as well as the existence of dynamic scatterers, the V2V channel is nonstationary. To account for the nonstationarity, channel characterization methods that employs the non wide-sense...
RS is a popular FH code whose chaotic features of frequency sequence is analyzed in this article and such a conclusion is achieved that RS code is of chaotic features in terms of frequency sequence. According to this conclusion, a method of FH prediction about the degree of incidence is suggested based on the phase space reconstruction of chaotic system. It is more accurate than the chaos prediction...
Due to the self rotation and revolution of the earth and the satellite moving comparatively, the delay rate changes intricately and that affects correlation result when we use VLBI to detect Satellite. To solve the problem, a new method of delay-delay rate 2-D correlation is proposed which based on time-frequency 2-D correlation. This method applies ambiguity function calculation of time-frequency...
Communication in acoustic particle velocity channel using vector sensors is recently proposed for the underwater medium. Due to the presence of multiple propagation paths, a mobile receiver collects the transmitted signal with different delays and Doppler shifts. This introduces certain delay and Doppler spreads in particle velocity communication channels. In this paper, these channel spreads are...
In this work we study the relation between time reversal and wave transport in (mainly 2D) systems with anisotropic disorder. It is shown, in particular, that for relatively short wavelengths which are comparable to the correlation scales of the disorder, the transport properties of random media are essentially different in the directions along and across the correlation ellipse. Fast propagation...
Ergodic capacity is not a suitable information-theoretic measure for delay sensitive applications over fading channels. On the other hand, delay-limited capacity becomes zero for Rayleigh channels. In this case, the Capacity with Probabilistic Delay Constraint becomes useful. In, the maximum constant source rate that may be supported in a wireless system with a probability ?? of exceeding certain...
Traditional Orthogonal frequency-division multiplexing channel realization methods need transformations of transmission symbols between time and frequency domains and therefore result in quite a high computational complexity. In this paper, a channel realization method only in the frequency domain is proposed to reduce the complexity of simulation. An example following the IEEE 802.16m standard is...
In the OFDMA downlink, obtaining channel state information (CSI) from users is necessary for the base station (BS) to optimize network performance by intelligently allocating resources and scheduling mobile stations (MS). However, the overhead of obtaining CSI is a large burden and therefore, schemes to reduce CSI are necessary for a realizable system. By considering a MS's coherence time Deltatcoh...
This paper derives the theoretical bit error rate (BER) of the multiband orthogonal frequency division multiplexing (MB-OFDM) system for ultra wideband (UWB) communication. The proposed derivation takes into account the fading correlation caused by time and frequency spreading, which is one of the most significant factors in MB-OFDM UWB system. Moreover, the proposed formula gives consideration to...
In this paper, we described the correlations between uplink TCP packet latency, behavior of TCP and behavior of application. Pearson product moment correlation analysis and partial correlation analysis are worked out to characterize correlations between five user perceived parameters. Our study demonstrated that the packet latency in uplink direction mainly caused by TCP setup time instead of the...
SAW based RFID sensors can offer wireless, passive operation over harsh environments, and various device embodiments are used for retrieval of the sensed data. SAW has many unique advantages over possible competing technologies, including the following characteristics: passive, radiation hard, operable over wide temperature ranges, small, rugged, inexpensive, and identifiable. In a multi-sensory environment,...
As a basic multipath property required to allocate the pilot signal in orthogonal frequency division multiplexing (OFDM) and compose antennas in the multiple-input multiple-output (MIMO) technique, correlation coefficients of the complex envelope in the received signal level and phase in multipath channels were studied theoretically and by computer simulation in a domain with time, frequency, and...
This paper utilizes a novel evolutionary approach to proceed with signal acquisition in Global Navigation Satellite Systems (GNSS). The method controls search space bound of frequency shift and code delay to shorten signal acquisition time. Simulation results show that the proposed scheme can acquire more accurate signal parameters and take less signal acquisition time than the traditional method.
This paper considers a general approach for the computation of all functional characteristics of a probabilistic wireless channel model using a bidirectional parametric description. It is shown that under mild conditions the WSSUS property is valid for these models and explicit relations are derived for the computation of the time-frequency autocorrelation from which one can easily derive the Doppler...
In a slot-synchronized wireless communication system, a set of signature sequences can be derived by circularly shifting a base sequence with good auto correlation properties. In a time-dispersive channel, the sequences with different circular time shifts can be uniquely identified as long as their minimum separation in time is greater than the channelpsilas maximum delay spread. In this paper, we...
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