6780116
Joint MMSE Vector Precoding Based on GMD Method for MIMO Systems
We propose a geometric mean decomposition (GMD) based vector precoding (VP) for multiple input multiple output (MIMO) systems. Minimum mean square error (MMSE) criterion is used for the joint VP design. The application of GMD method eliminates the imbalance among subchannel gains and obtains a better perturbation vector than the conventional method. We then exploit the extended channel matrix for further performance improvement. Simulation results show the proposed schemes significantly outperform the existing VP schemes.
19596582
MMSE vector precoding with joint transmitter and receiver design for MIMO systems
The transmitter side (Tx) vector precoding (VP) shows excellent performance. However, joint transmitter and receiver (Tx-Rx) design might achieve further improvement. In this paper, we propose a novel joint Tx-Rx VP for multiple input multiple output (MIMO) systems. A unitary matrix is used at the receiver to partially equalize the channel. We design the joint Tx-Rx VP with the minimum mean square error (MMSE) criterion and deduce the general closed-form solution. Then we apply several methods including the singular value decomposition, QR decomposition and geometric mean decomposition (GMD) to specify the general joint Tx-Rx VP design. Moreover, by using the extended channel, we achieve an improved scheme to obtain further performance gain. Simulation results show that the specification with GMD method outperforms the other specifications and the Tx MMSE VP. The improved joint Tx-Rx MMSE VP with GMD is superior to other MMSE VP schemes.
35354920
Color text image binarization based on binary texture analysis
In this paper, a novel binarization algorithm for color text images is presented. This algorithm effectively integrates color clustering and binary texture analysis, and is capable of handling situations with complex backgrounds. In this algorithm, dimensionality reduction and graph theoretical clustering are first employed. As the result, binary images related to clusters can be obtained. Binary texture analysis is then performed on each candidate binary image. Two kinds of effective texture features, run-length histogram and spatial-size distribution related respectively, are extracted and explored. Cooperating with an LDA classifier, the optimal candidate of the best binarization effect is obtained. Experiments with images collected from Internet has been carried out and compared with existing techniques, both show the effectiveness of the algorithm.
32866926
Lattice-Reduction-Aided MMSE Tomlinson-Harashima Precoding for MIMO Systems
In this letter, a lattice-reduction-aided (LRA) minimum mean square error (MMSE) Tomlinson-Harashima precoding (THP) is proposed for multiple input multiple output (MIMO) systems. The extended channel is exploited to develop the LRA MMSE-THP based on the lattice reduction method. Simulation results show that the proposed scheme significantly outperforms the conventional MMSE THP and the LRA zero-forcing (ZF) THP and achieves full diversity order.
1077673
Low Complexity MMSE Vector Precoding Using Lattice Reduction for MIMO Systems
In this paper, a lattice-reduction-aided (LRA) minimum mean square error (MMSE) vector precoding (VP) is proposed for multiple input multiple output (MIMO) systems. Three schemes are provided for the perturbation vector design by Babai's approximation procedures based on lattice reduction method to reduce the complexity. Performance and complexity analysis are provided. Simulation results show that the proposed schemes significantly outperform the conventional MMSE Tomlinson-Harashima precoding (THP) and the zero forcing (ZF) VP. Compared with the MMSE VP via closest-point search, our LRA approach provides a simple alternative with little performance loss.
8081608
An analytic model for Ge/Si core/shell nanowire MOSFETs considering drift-diffusion and ballistic transport
In this paper an analytic model for Ge/Si core/shell nanowire MOSFETs (NWFETs) is developed. First, the electrostatic potential and charge model are derived out from classical device physics. Then the drift-diffusion drain current model is obtained and verified by comparisons with the numerical simulation. The ballistic current model is obtained with the approximately described quantummechanical effect through modifying the intrinsic carrier concentration under 2-dimensional confinement. With the proposed model, the performances of Ge/Si core/shell NWFETs are analyzed and significant characteristics are demonstrated in details. The analytic model in this paper provides a framework for further developing compact models of the NWFETs with Ge/Si core/shell heterostructure for circuit design and simulation.
15290782
The Performance Analysis of an Improved Robust Beamforming Algorithm
The conventional minimum variance beamformer (MVB) is known to have better resolution and much better interference rejection capability when the array steering vector is accurately known. However, the major problem of the MVB is that it lacks robustness against the unknown array steering vector errors. Therefore, diagonal loading and its extended versions have been a popular approach to improve the robustness of MVB. In this paper, we provide an improved robust MVB (RMVB) algorithm, which has been derived by enforcing a spherical uncertainty set constraint on the array steering vector. The new algorithm has reasonable computation complexity and more numerical stability. Simulation results show that the new algorithm is effective in the presence of array steering vector errors.
16207810
Web Services Methods for Communication over IP
In this paper, we study Web services methods and approaches to enable real-time communication services over IP. This approach extends Web services methodologies from service integration to a service-oriented approach for communication. In particular, we describe the generic Web service based application session management, WS-Session, the two-way full duplex Web service interaction framework, and most importantly, the development of Web service initiation protocol (WIP) which is a full featured Web service and SOA based communication framework for multimedia and voice communication over IP. We show that WIP provides a service oriented architecture which can be extended seamlessly from a P2P endpoint to an endpoint with advanced call control and switching capabilities typically requiring the assistance of a dedicated PBX. A prototype of WIP system is fully developed. Architectural design and system implementation of Web service based communication endpoints are studied and applied to realize service-oriented communication over IP. Advances of WIP indicate the beginning of a full Web service and SOA based communication paradigm that can reshape the converged communication over IP.
17180210
An efficient distributed algorithm for constructing delay- and degree-bounded application-level multicast tree
In this paper we investigate the problem of finding a delay- and degree-bounded maximum sum of nodes application level multicast tree. We then proved the problem is NP-hard, and its relationship with the well-studied degree-bounded minimum maximum-delay multicast tree problem. We propose a distributed algorithm - OverStream, which adopts PPAF heuristic for father node to choose optimal child nodes based on multiple network parameters. Simulation results show that our algorithm is better than OMNI, SpreadIt, HMTP, and Zigzag in general.
21928964
Energy-aware optimal workload allocation among the battery-powered devices to maximize the co-operation life time
Traditional low power design minimizes the total power consumption. However for systems that want to maximize co-operation life time among the battery-powered devices, the total power minimization strategy may not be the best. The workload allocation among these devices has a dramatic impact on the co-operation life time. In this paper, we address this problem by formulating it as a linear programming (LP) problem. A simplified energy-aware algorithm is proposed to provide the optimal solution according to the energy capacity ratio of the devices. This algorithm is simple enough to be embedded into real-time system and we illustrate this by an example using a configurable transmitter-receiver pair. Experimental results show that the proposed algorithm significantly outperforms the other workload allocation strategies by 400.66% in the randomly-generated systems and 23.20% in a point-to-point (P2P) communication system, respectively