16922329
A New Transmit Scheme Combining Beamforming with Space-Time Block Coding
In this paper, a new transmit scheme combining beamforming (BF) with space-time block coding (STBC) is proposed for correlated fading channels. Based on maximizing the output mean signal-to-noise ratio (SNR) at the receiver, the transmitter BF weight vectors are first derived. Then, utilizing the minimal bit error rate (BER) upper bound as the design criterion, a simple power allocation algorithm is developed. Next, the BER performance of the system with the proposed transmit scheme is analyzed by considering an M-QAM constellation. Finally, computer simulation results are given to verify the effectiveness of the proposed scheme.
8006585
Linear Transceiver Design for Multiuser MIMO Downlink
An iterative linear transceiver design scheme under sum mean squared error minimization criterion is proposed. By modifying the structure of transceiver, the complex computation of Lagrangian multiplier within traditional MMSE transceiver design can be effectively obviated, and thus the whole system complexity can be greatly reduced. Because the Lagrangian multiplier has analytical solution, transmit preceding matrix also has closed-form solution, and can be solved easily with fixed- point iterations. The receiver filter is worked out independently with MMSE criterion at each terminal, and the downlink signaling of each receive filter from base station is not necessary- Simulations demonstrate that the proposed scheme is effective.
16889097
Limited Feedback Precoding Based on Hierarchical Codebook and Linear Receiver
The analysis shows that the conventional codebook construction of Grassmannian subspace packing can not control the performance loss caused by a linear receiver, while a proper unitary perturbation to the codebook is capable of compensating for this performance loss. This paper therefore proposes a novel hierarchical codebook to exploit the gain of unitary perturbation. The hierarchical codebook consists of a Grassmannian subcodebook and a proposed perturbation subcodebook. To implement precoding, this paper also presents a successive codeword selection scheme, thus the receiver would successively selects two preferred codewords from Grassmannian and perturbation subcodebooks. With the feedback binary indices of these selections, the transmitter uses the product of two preferred codewords as the precoder. The theoretical analysis of the proposed precoding technique shows that the usage of the perturbation subcodebook can improve to a certain degree the system performance in terms of throughput as well as BER, with a small additional feedback overhead, and the proposed codebook would reduce the computational and storage requirements in contrast to the conventional codebook. It is also shown via computer simulations that the proposed technique gives a better BER performance than the single Grassmannian codebook based precoding technique does, even if the feedback overhead remains the same.
15163844
Towards a Coordination Infrastructure for Pervasive Computing Environment Based on Tuplespace and Semantic Web
Pervasive computing is an emerging computing paradigm, which is expected to be part of our everyday life in the foreseeable future. The coordination among heterogeneous devices, services, and software agents will be vital for ensuring the success of their interactions. Tuplespace (TS) offers a coordination infrastructure for communication. With pervasive computing environment which is characterized as an open and dynamic distributed system become more ubiquitous, autonomous, and complex, this can pose some limitations to TS. In this paper we introduce Semantic Tuplespaces (STS) based on a combination of Semantic Web technologies and tuplespace computing. It acts as a middleware to enable communication and coordination based on the principle of publish and retrieve of semantic information. We describe overview of the conceptual model and discuss the necessary extensions to the original tuplespace. An initial version of the STS prototype system has been implemented based on Jena and Pellet, a DL reasoner. Finally, through an elaborate use case, we show the usability and benefits of our approach.
38238585
Exploiting multi-scale support vector regression for image compression
Unlike traditional neural networks that require predefined topology of the network, support vector regression (SVR) approach can model the data within the given level of accuracy with only a small subset of the training data, which are called support vectors (SVs). This property of sparsity has been exploited as the basis for image compression. In this paper, for still image compression, we propose a multi-scale support vector regression (MS-SVR) approach, which can model the images with steep variations and smooth variations very well resulting in good performance. We test our proposed MS-SVR based algorithm on some standard images. The experimental results verify that the proposed MS-SVR achieves better performance than standard SVR. And in a wide range of compression ratio, MS-SVR is very close to JPEG in terms of peak signal-to-noise ratio (PSNR) but exhibits better subjective quality. Furthermore, MS-SVR even outperforms JPEG on both PSNR and subjective quality when the compression ratio is higher enough, for example 25:1 for Lena image. Even when compared with JPEG-2000, the results show greatly similar trend as those in JPEG experiments, except that the compression ratio is a bit higher where our proposed MS-SVR will outperform JPEG-2000.
19385120
DJ DreamFactory
DJ DreamFactory is a web-based integrated platform for interactive broadcasting over the Internet. In DJ DreamFactory, users are able to set up Internet-based broadcasting stations with minimal effort. Audience not only can receive broadcasting programs from multiple stations through this unified platform, but can also "talk" and "write" to the broadcasters as well as to other audience via real-time text and/or audio interactions.
3197098
A Multi-Objective Hw-sw Co-Synthesis Algorithm Based on Quantum-Inspired Evolutionary Algorithm
Hardware–Software (HW–SW) co-synthesis is one of the key steps in modern embedded system design. Generally, HW–SW co-synthesis is to optimally allocate processors, assign tasks to processors, and schedule the processing of tasks to achieve a good balance among performance, cost, power consumption, etc. Hence, it is a typical multi-objective optimization problem. In this paper, a new multi-objective HW–SW co-synthesis algorithm based on the quantum-inspired evolutionary algorithm (MQEAC) is proposed. MQEAC utilizes multiple quantum probability amplitude vectors to model the promising areas of solution space. Meanwhile, this paper presents a new crossover operator to accelerate the convergence to the Pareto front and introduces a PE slot-filling strategy to improve the efficiency of scheduling. Experimental results show that the proposed algorithm can solve the typical multi-objective co-synthesis problems effectively and efficiently.
14518520
Design and Implementation of an Automated Microscope Stage
Optical microscopes remain keen instruments for scientific research nowadays. Widely used in hospitals and laboratories, such equipment helps people deal with various kinds of tasks, most of which, however, are both onerous and tedious; therefore, operations on these manually executed instruments are lengthily and subject to human errors. To alleviate this problem, we equip an optical microscope with two stepper motors and implement the automatic control of the microscope stage. This paper introduces the control system architecture and discusses in detail the development of the communication subsystem and the stepper motor controllers. Test results with a practical application are also provided to illustrate the performance of this system.