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To provide a quantitative description for noisy multiuser performance of chaos-based communications, this paper presents an simple and effective approach for analyzing the noisy multiuser performance of coherent CSK (chaos-shift-keying) system with two basis functions under a noisy multiuser environment. Using a Logistic map as the chaotic signal and assuming ideal synchronization at receiver, the...
For non-contiguous OFDM (NC-OFDM) based cognitive radio (CR) systems, one of huge challenges is to establish spectrum synchronization before data transmissions. In this paper, we propose a novel active subchannel detection scheme for the NC-OFDM receiver without out-of-band spectrum synchronization information. The key idea of the proposed scheme is to employ the received training symbol to calculate...
Multi-gigabit per second wireless network devices are emerging for personal area networks (PAN) in the 60 GHz band. Such devices are typically power hungry, largely due to the requisite high speed analog to digital converters (ADCs) that can consume from tens to hundreds of milliwatts of power. This paper studies the use of analog equalization before the ADC to reduce the required ADC resolution....
The existing transmit diversity schemes for time domain synchronous OFDM (TDS-OFDM) is only suitable either for fast time-varying but weakly frequency-selective channels, or strongly frequency-selective but slow fading channels. In this paper, the space-time shifted constant amplitude zero autocorrelation (CAZAC) sequence based TDS-OFDM transmit diversity scheme is proposed for doubly selective channels...
The performance in fading of two dual signal-plus-noise (S+N) selection combining (SC) diversity structures employing different filtering is examined. The proposed structure includes either a minimum mean square error filter or a lowpass filter designed to reduce the noise in the signal used for determining the antenna switching times. The switching rate and the bit error rate of the proposed structures...
We propose the use of a complex orthogonal distributed space-time code within a two-hop cooperative wireless four relay network, which can achieve asymptotically full rate and full cooperative diversity. In this scheme the four relay nodes are arranged as two groups of two relay nodes, both of which employ the Alamouti distributed space time block coding (DSTC) design, but with offset transmission...
Land mobile satellite (LMS) channels can be modelled accurately by the shadowed-Rice (SR) fading model. Recently, an approximate SR model is proposed by the author for LMS channels. Compared with the existing models, the proposed model is analytically tractable and makes it possible to approximate very accurately the probability density function (PDF) of the SR random variable (RV) by a finite weighted...
In this contribution, a multi-user receiver for M-QAM MIMO-OFDM operating in time-varying and frequency-selective channels is derived. The proposed architecture jointly performs semi-blind estimation of the channel weights and noise inverse variance, serial interference cancellation and decoding in an iterative manner. The scheme relies on a variational message-passing approach, which enables a joint...
We study and propose power control schemes for cognitive radios in Nakagami fading channels. A general model is adopted, which includes the effects of transmit power control from the primary user (PU) transmitter, as well as the transmit power control from multiple secondary user (SU) transmitters, to the PU and each SU. We found that for high signal-to-interference-ratio (SIR) case in Nakagami and...
In this paper we propose current-mode echo cancellation technique for full-duplex chip-to-chip data communication. A new hybrid circuit topology suitable for current-mode echo cancellation is presented. The hybrid circuit topology is shared integration of an operational transconductance amplifier(OTA) and a transimpedance amplifier(TIA). The output/back-port impedance of the hybrid is matched with...
This paper describes low power architecture by using a dynamic wordlength technique in wireless orthogonal frequency division multiplexing (OFDM) system. The number of wordlength in digital signal processing (DSP) has to be carefully determined because wordlength affects system performance and hardware cost. Dynamic wordlength technique is applied to a fast Fourier transform (FFT) processor and a...
In this paper, the difference in performance between using a matched filter and an integrate and dump filter to implement a correlator in a GPS receiver is studied; in case of infinite and of limited bandwidth; and in case of infinite and of finite sampling frequency. Obviously, the matched filter outperforms the much easier to implement integrate and dump filter on accuracy of synchronization and...
This paper presents the experimental results of single carrier digital modulation schemes for underwater sensor networks. To obtain a real sea data of acoustic communications, an experiment was performed at the shallow water environments. ASK and FSK were used as non-coherent modulation scheme and QPSK and 16-QAM are used as coherent modulation scheme. Except for 16 QAM, the experimental results represent...
In the MIMO-OFDM system, the carrier frequency offset and phase noise cause loss of orthogonality among subcarriers and leads to intercarrier interference (ICI). This paper considers ICI self-cancellation schemes using space frequency block code (SFBC) in MIMO-OFDM system. In this paper we have analytically derived expression for common phase error (CPE), ICI, carrier to interference (CIR) and BER...
Orthogonal frequency-division multiplexing (OFDM) has been able to successfully exploit channel state information (CSI) at the transmitter, allowing to implement dynamic resource allocation schemes that improve spectral efficiency and error resilience. In most wireless communication systems, though, achieving a perfect CSI at the transmitter is difficult. For this reason a limited-rate feedback mode...
Simulation of vehicular communications is demonstrated to strongly depend on a plethora of settings which are often managed in a simplistic way. For instance heavy impact on bit-error-rate and packet-error-rate may come from physical layer phenomena which are either neglected - to make the overall simulation process faster - or managed by computationally heavy simulators - as in ray-tracing. As a...
Systems employing multiple FPGAs to handle distributed processing require data communication among FPGAs for unified operation. This paper describes implementation of a multi-lane Low Voltage Differential Signaling (LVDS) interface to form 10 Gbps full duplex communication link interconnecting multiple FPGAs on a board. The design utilizes advanced IO resources available in the latest Virtex and Spartan...
Contrast to the adaptive equalization method, which need a training period, blind equalization technique, which only the output signal is known, is needed in many communication systems, such as multipoint data network or wireless communication systems. In this paper, a new blind equalization approach, called expectation maximization blind equalization (EM-BE), is proposed. First, transform the convolution...
Software Defined Radio (SDR) based tools of identification may increase with the diffusion of frequency agnostic modes of radio frequency identification (RFID). Similarly, fixed frequency readers may be replaced with interrogators that can operate in any frequency. SDR is a feasible solution for RFID signal, which can perform different functions at different times on the same hardware. Pilot Symbol...
A joint filter using lattice predictor based adaptive Volterra filter(LVF) is proposed to effectively suppress narrowband interference (NBI) in Global Positioning System (GPS) receiver. A lattice structure is employed for whitening the input signal. The performance is expressed in terms of BER and SNR improvement. Computer simulation results show that LVF can achieve excellent performance in terms...
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