In this paper, an improved and low-complexity sampling clock frequency offset (SFO) estimation scheme is proposed for orthogonal frequency division multiplexing (OFDM) based digital radio mondiale(DRM) systems. In order to devise the low-complexity SFO estimator, some modifications on the conventional estimator are highlighted with an emphasis on the selection of pilot subcarrier.
The method based on Bag-of-visual-Words (BoW) deriving from local keypoints has recently appeared promising for video annotation. Spatial partition scheme has critical impact to the performance of BoW method. In this paper, we propose a new adaptive annular spatial partition scheme. The proposed scheme firstly determines the centroid of partition according to the distribution of keypoints. And then the image is partitioned into several annular regions. In the end, BoW histograms are computed according to the annular regions, which are utilized to train SVM classifiers. A systematic performance study on TRECVID 2006 corpus containing 20 semantic concepts shows that the proposed scheme is more effective than other popular spatial layout partition schemes such as 2 × 2 grid scheme.
This study proposes an improved data-directed carrier frequency offset (CFO) estimator for ultra-wideband multi-band orthogonal frequency division multiplexing (UWB MB-OFDM) systems. Our approach is based on two adjacent OFDM symbols which convey the identical information on an UWB-OFDM system. To demonstrate the efficiency of the proposed CFO estimator, comparisons were made with existing data-aided estimators in terms of mean square error.
This paper presents a highly linear mm-wave low noise amplifier utilizing a linear attenuating output stage. An analytical method is given for optimum design of this stage by Volterra series. Using a 0.13µum CMOS technology, the IIP3 is improved by more than 10dB reaching to +6dBm, without any extra power consumption. The LNA has a flat gain of 12.7dB with less than ±0.1dB variation from 26 to 35.8GHz and consumes 15.6mW of power. While the input-output matching requirements are well satisfied for this LNA, its noise figure is below 3.7dB over the entire band.
The coded cooperative communication technique utilizes single antenna mobiles in a multi-user environment that share their antennas and incorporate channel coding schemes in order to achieve transmit diversity. This letter presents a new coded cooperation system based on Reed Solomon codes. The RS codes are very effective in correcting random symbol errors and random burst errors over fading channels. The new coded cooperation system splits the data into two frames, using a vector arithmetic operation. The performance of the new system as compared to the coded cooperation system that utilizes the Rate-Compatible Punctured Convolutional (RCPC) coded cooperation is significantly superior with improvement for full diversity gain is around 10dB under variety slow fading channel conditions.
In the shortest path routing algorithm for communication networks, the end-to-end path of each session is found such that the sum of weights of links on the path is minimized. Hence, to find a `good' path for each session, it is important to assign the appropriate weight to each link in the network. In this paper, we study this problem considering the utilization of each link. Since this problem is known to be NP-hard, we use a heuristic approach. Our algorithm is based on the simulated annealing algorithm. However, with taking into account the properties of our problem, we modify the basic simulated annealing algorithm, which results in a faster and more robust convergence.
Thermal effects were investigated in a liquid crystal display (LCD) backlight unit (BLU) that was composed of light emitting diode (LED) arrays. The driving power for a single LED in a BLU is determined by the desired brightness of the LCD panel and the pitch distance between adjacent LEDs. As the pitch distance increases, individual LEDs need to be driven by a higher power in order to maintain the same brightness. Since the junction temperature of an LED plays an important role in LED performance, such as optical efficiency, intensity degradation, and lifetime, the maximum driving power for an LED should be limited by a critical level of the junction temperature. A guideline for designing LED BLU panels taking account of the junction temperature is presented using various parameters of LED arrays.