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Reducing the complexity and power consumption of the Viterbi decoder is one of the important design goals for high throughput wireless systems. Recently, a low complexity decoding algorithm was proposed to reduce the average number of ACS (Add Compare Select) operation of the Viterbi algorithm (VA) using the information of syndrome. Unfortunately, it has two limitations: the large computation overhead...
A new RF modified linear amplifier using nonlinear components (LINC) architecture for wireless communication links is proposed and evaluated in this work. The layout of the new architecture is presented and the simulation results are presented to show the performance under different operation conditions and channel types. Results show that the overall power efficiency of this architecture is improved...
A novel biquad circuit is presented that allows the loop filter of a high-order continuous-time sigma-delta modulator to be implemented by cascading low-order biquad sections, considerably easing the design and implementation of the high-order continuous-time sigma-delta modulator. Experiment on a 4th-order bandpass continuous-time sigma-delta modulator is conducted successfully and the results are...
In this paper we address the potential gain of using compact MIMO antenna array configurations in conjunction with HAP diversity techniques in order to increase the data rates in HAP communication systems. Simulation results show that the MIMO system provides superior performance as compared to the single HAP case.
A multi-LO frequency synthesizer block for MB-OFDM UWB systems is proposed, which is implemented in 0.18 mum CMOS technology. The proposed frequency synthesizer can provide three LO tones and quadrature IF LO tone from only one VCO. Based on an optimized frequency plan, it uses fewest nonlinear components like divide-by-N and mixer to suppress unwanted spurious tones. Its measured in-band sideband...
Fast Fourier transform (FFT) is a key building block for orthogonal frequency division multiplexing (OFDM) systems. Due to the development of wireless portable devices, it is important to minimize the size and power of a FFT processor. One of the methods to satisfy such demands is reducing the size of twiddle coefficient memory. This paper presents an effective coefficient memory reduction scheme...
This investigation presents a modified selected mapping (SLM) scheme for reducing the peak-to-average power ratio (PAPR) of an OFDM transmitted signal using a discrete Fourier transform (DFT) and a discrete cosine transform (DCT) kernel is proposed and investigated. The coefficient array of DFT or DCT is designed to reduce the correlation among original QAM constellations. In this technique, the preprocessing...
In this paper, we introduce a successive cancellation channel estimation scheme based on the preamble structure suggested in the DS-UWB proposal of IEEE P802.15.TG3a. In order to improve the transmission efficiency, we reduce the length of preamble defined in the proposal without sacrificing the channel estimation performance. The gain on the transmission efficiency is discussed for different data...
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