Tensor-Based Channel Estimation Approach for One-Way Multi-Hop Relaying Communications

( Shuangzhi Li ),( Xiaomin Mu ),( Xin Guo ),( Jing Yang ),( Jiankang Zhang ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.12

Multi-hop relaying communications have great potentials in improving transmission performance by deploying relay nodes. The benefit is critically dependent on the accuracy of the channel state information (CSI) of all the transmitting links. However, the CSI has to be estimated. In this paper, we investigate the channel estimation problem in one-way multi-hop MIMO amplify-and-forward (AF) relay system, where both the two-hop and three-hop communication link exist. Traditional point-to-point MIMO channel estimation methods will result in error propagation in estimating relay links, and separately tackling the channel estimation issue of each link will lose the gain as part of channel matrices involved in multiple communication links. In order to exploit all the available gains, we develop a novel channel estimation model by structuring different communication links using the PARAFAC and PARATUCK2 tensor analysis. Furthermore, a two-stage fitting algorithm is derived to estimate all the channel matrices involved in the communication process. In particular, essential uniqueness is further discussed. Simulation results demonstrate the advantage and effectiveness of the proposed channel estimator.

Dynamic Spectrum Access with Spatial Reuse

Ying Liu,Guangqiang Shi,Xiaomin Mu 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.1

We investigate the problem of achieving utility function optimization for distributed channel selection using game theoretic solutions in opportunistic spectrum access system, where secondary users are spatially located and mutual interference only emerges between neighboring users. In addition, interference graph of spatial position is introduced to measure interference and evaluate the possible opportunities of spectrum access. Based on this we propose an optimization problem of minimizing loss throughput, which is solved by a game theory and an optimal channel selection set is derived. The main work of this paper is to prove that this game is an exact potential game, which has at least one pure strategy Nash equilibrium. Finally simulation results is given to verify the correctness of the theoretical analysis. Especially meanwhile after considering spatial reuse by users’ position, the system throughput is significantly increased, thus the spectrum utilization rate is effectively improved.

Energy Efficiency Optimization for Uplink Multiuser MIMO Systems

Lina Ma,Shuangzhi Li,Xiaomin Mu 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.8

To satisfy green communication needs, energy efficiency is regraded as one of the most important indicators to evaluate the effectiveness of a communication system. In this paper, we establish the energy efficiency optimization framework for uplink multiuser mutliple-input multiple-output system. Taking the circuit power, the antenna link power and signal processing power into consideration, an analytical expression of the achieveable energy efficiency is firstly established, which can better model the practical communication process. Furthermore, we simplify the objective function under some mild conditions. After demonstrating the existence of a unique golbally optimal energy efficiency, an adaptive water-filling power allocation algorithm is proposed to further improve the energey efficiency of the system. Finally some simulation results are given to verify the performance of our scheme. Our work can provide a fundamental principles for uplink mutiluser multiple-input multiple-output systems design.

Energy Efficiency of Very Large Multiuser MIMO Systems with Transmit Antenna Selection

Jie Li,Shuangzhi Li,Xiaomin Mu,Jiankang Zhang 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.6

In this paper, transmit antenna selection is performed to improve the energy efficiency of multiuser large scale MIMO systems, which is necessary for the energy efficiency maximization of large scale MIMO, because the RF chains which are connected with antennas are very expensive and consume a lot of power. However, the consumed power of the large scale MIMO systems should include not only transmit power but also the fundamental power for operating the circuit at the transmitter, because the effect of circuit power consumption is more serious when the transmitter is equipped with massive number of antennas. We evaluate the performance of the energy efficiency in the multiuser case where zero-forcing precoding is used to reduce the inter-user interference. The theoretical analysis indicates that there exists an optimal number of selected antennas to maximize the energy efficiency, and we derive optimal antenna number for different number of users. All the analytical results are verified through both mathematical analysis and numerical simulations.

Cooperative Spectrum Sharing in Cognitive Radio Networks : A Centralized Contracted-Based Approach

Guangqiang Shi,Ying Liu,Xiaomin Mu 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.3

In this paper, we study the relay-based communication schemes for cooperative spectrum sharing among multiple primary users (PUs) and multiple secondary users (SUs) with incomplete information. Inspired by contract theory, we model the network as a labor market. In this market, PUs and SUs are regarded as employer and employee respectively. Each PU proposes certain contracts to attract the SUs, the contract include relay power and spectrum access time, each SU maximize its utility by selecting the most suitable contract. But PUs and SUs have conflicting objectives in contract content. To tackle this problem, we put forward to a centralized maximizing expectation utility scheme, which convert the optimal contract design into an optimization problem. After that, a approximate method for solving the optimization problem is proposed. Simulation results show that the losses of PUs’ total utilities caused by incomplete information and approximate algorithm are relatively small, especially when the number of SUs is very large.

Energy Efficiency Resource Allocation for MIMO Cognitive Radio with Multiple Antenna Spectrum Sensing

( Bing Ning ),( Shouyi Yang ),( Xiaomin Mu ),( Yanhui Lu ),( Wanming Hao ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.11

The energy-efficient design of sensing-based spectrum sharing of a multi-input and multi-output (MIMO) cognitive radio (CR) system with imperfect multiple antenna spectrum sensing is investigated in this study. Optimal resource allocation strategies, including sensing time and power allocation schemes, are studied to maximize the energy efficiency (EE) of the secondary base station under the transmit power and interference power constraints. EE problem is formulated as a nonlinear stochastic fractional programming of a nonconvex optimal problem. The EE problem is transformed into its equivalent nonlinear parametric programming and solved by one-dimension search algorithm. To reduce searching complexity, the search range was founded by demonstration. Furthermore, simulation results confirms that an optimal sensing time exists to maximize EE, and shows that EE is affected by the spectrum detection factors and corresponding constraints.

Pilot Symbol Assisted Weighted Data Fusion Scheme for Uplink Base-Station Cooperation System

( Zhe Zhang ),( Jing Yang ),( Jiankang Zhang ),( Xiaomin Mu ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.2

Base Station Cooperation (BSC) has been a promising technique for combating the Inter-Cell Interference (ICI) by exchanging information through a high-speed optical fiber back-haul to increase the diversity gain. In this paper, we propose a novel pilot symbol assisted data fusion scheme for distributed Uplink BSC (UBSC) based on Differential Evolution (DE) algorithm. Furthermore, the proposed scheme exploits the pre-defined pilot symbols as the sample of transmitted symbols to constitute a sub-optimal Weight Calculation (WC) model. To circumvent the non-linear programming problem of the proposed sub-optimal model, DE algorithm is employed for searching the proper fusion weights. Compared with the existing equal weights based soft combining scheme, the proposed scheme can adaptively adjust the fusion weights according to the accuracy of cooperative information, which remains the relatively low computational complexity and back-haul traffic. Performance analysis and simulation results show that, the proposed scheme can significantly improve the system performance with the pilot settings of the existing standards.