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The following topics are dealt with: VLSI; OFDM; embedded systems; filters; MIMO; cellular and integrated systems; media processing; Internet; image processing; network routing; QoS and resource allocation; network management; channel modelling and equalization; ad hoc networks; communication signal processing; WSN; channel estimation; WLAN and WWAN; coding and detection; security; UWB; cognitive...
This paper presents performance analysis of Residue Number System (RNS) based Finite Impulse Response (FIR) digital filters and traditional FIR filters. This research is motivated by the importance of an efficient filter implementation for digital signal processing. The comparison is done in terms of speed and area requirement for various filter specifications. RNS based FIR filters operate more than...
When employing multibit data converters the necessity arises to compensate for digital to analog converter (DAC) element mismatch. The most widespread compensation techniques are based on digital element matching (DEM) and, if properly designed, these can achieve almost arbitrary DAC mismatch noise shaping. This paper gives a closed form expression for the optimal DEM noise shaping profile. It depends...
Due to the development of wireless communication systems, the linearity requirement of power amplifiers (PAs) is very stringent. A new concept was proposed to model a predistorter directly without modeling a PA firstly. The algorithm can not only improve the linearity of amplifier, but also adjust the gain of PAs dependently. Based on this algorithm, the behavioral model and structure of the predistorter...
A dual-planar RFID tag is designed and developed. Its performance is verified with both simulated and experimental results. The novel design proposed here gives a 3-dB beamwidth of 152deg and a gain of 4.65 dBi at 2.44 GHz. The proposed design greatly reduces the sensitivity to orientation and to conductive material of the conventional RFID system, which degrades its performance. The dual-planar RFID...
An important challenge in Optical Burst Switching (OBS) is to reduce the burst loss caused by contention. In this paper we develop a new method that improves the burst loss probability by burst re-routing in case of contention. Our rerouting method guarantees that bursts (that are not discarded) are routed towards the egress on a loop-free path We have made a detailed discrete event simulation model...
In this work, we propose a quick response circuit to improve the load transient response of fully low dropout voltage linear regulator (LDO) which is operable with a very low power consumption. Simulating by HSPICE with 0.35 mum CMOS technology shows that we can achieve the transient responses with less transient overshoot or undershoot when driving large current loads. Comparing to the generic LDO,...
In this paper a novel structural silicon on insulator (SOI) LDMOS with trench gate and field plate and trench drain (TGFPTD) is firstly proposed. The proposed TGFPTD SOI LDMOS is mainly characterized of a vertical channel and channel current spreading area, a lateral drift region, a field-stopping doped area, a trench drain as well as nearly the most homogenous current flowing through the drift region...
This article presents the modified design for a basic current-mode building block for analog signal processing, named as current controlled current differencing buffered amplifier (CCCDBA). Its parasitic resistances at two current input ports can be controlled by an input bias current. The output current and voltage offsets including power consumption are low compared to ordinary CCCDBA description...
This paper presents a novel approach for model order reduction of linear time varying system based on Response Dependent Condensation (RDC). The proposed scheme is developed through introducing RDC to time-varying transfer functions. This scheme does not require solution of large system of equations to construct a basis for the time-varying moments. Instead, it computes such a basis through time-domain...
Analog-to-digital converter designs are considerably becoming critical parts of wireless receiver improvement studies. Delta-sigma ADCs, which offer high-resolution, low cost and low power benefits are tested for aptness for the ZigBee standard - an emerging standard developed to address the needs of wireless sensing and control based on IEEE 802.15.4. Eight fully integrated delta-sigma analog-to-digital...
This paper presents a quadrature voltage-controlled oscillator (QVCO) based on the coupling of two LC-tank VCOs. The QVCO could be tuned between 2.41 and 2.64 GHz, and showed a phase noise of -139 dBc/Hz at 1 MHz offset frequency from the carrier across the whole tuning range, for a current consumption of 20 mA with 2.5-V power supply. A figure-of-merit of -190 dBc/Hz is observed.
The paper presents the design and implementation of six operational amplifiers with rail-to-rail input and output capability. The study characterizes several rail-to-rail input and output stages and the dependence of the op-amp's operation on different design parameters to formulate a standard design methodology that can serve as a guide for future researches and projects in the area of rail-to-rail...
Orthogonal frequency division multiplexing (OFDM) has been used widely in many communication systems. However, the major drawback of OFDM is the high peak-to-average-power ratio (PAPR) which results in the bit error rate (BER) performance degradation in nonlinear environments. In this paper, we introduce a new phase weighting method to reduce the nonlinear distortion of OFDM signals in the nonlinear...
Interleaving method belongs to the phase rotation group which is one of the famous PAPR (peak to average power ratio) reduction method in orthogonal frequency-division multiplexing (OFDM) system. The phase rotation method has advantage to reduce the PAPR without spectrum distortion and very flexibly. But, it needs so many IFFT blocks and the side information must be additional included for the correct...
This paper proposes a new approach to block spread OFDM called parallel concatenated spreading matrices OFDM (PCSM-OFDM). While BSOFDM improved the overall BER performance on OFDM in frequency selective channels, this new approach further improves the BER of BSOFDM by a 3 dB gain. This is achieved through increasing the diversity of the transmitted samples by concatenating two spreading matrices in...
In this paper we propose an interleaved spread spectrum orthogonal frequency division multiplexing (ISS-OFDM) transmission scheme and demonstrate its reduced peak-to-average power ratio (PAR). The proposed ISS-OFDM signal is realized by two steps. The first step is to modulate the data symbol by complex exponential spreading and the second is to use an interleaving technique to spread the signal spectrum...
OFDM (Orthogonal frequency division multiplexing) is one of the key techniques for 4th generation high data rate communications system. However OFDM suffers from high peak-to-average power ratio (PAPR) which substantially degrades the efficiency of a linear power amplifier. A new nonlinear companding transform using hyperbolic tangent sigmoid transfer function is proposed for PAPR reduction in this...
A new tone reservation (TR) scheme for the Peak-to-average power ratio (PAPR) reduction in the orthogonal frequency division multiplexing (OFDM) system is proposed. Different from the conventional TR scheme, the cancellation signals are generated by using FFT/IFFT iteration. Simulation results show that the new TR scheme based on FFT/IFFT has a perfect PAPR reduction performance and the number of...
For a multi-user orthogonal frequency division multiplexing (OFDM) system, system reliability, availability and fairness should be guaranteed simultaneously. Resource allocation problem for such systems can be described as maximizing overall throughput while satisfying requirement of fairness, subject to power restriction and quality of service (QoS) requirement. Existing researches provide solution...
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