RPPK modulation with high data rates

With the development of communication technology, the precious frequency spectrum is becoming more and more crowded. Exploiting the particular filter with zero group delay, ultra narrow band (UNB) modulation is intended for acquiring the high frequency efficiency. Unfortunately, this UNB filter is confronted with great challenges from the classical communication theories. The validation on its realization is also difficult. This paper proposes a novel UNB modulation, namely random pulse position keying (RPP...     

一种多用户MIMO/OFDMA系统的资源分配和调度方案

针对下行多用户多入多出／正交频分复用系统,提出了一种适合多业务类型的资源分配和调
度算法. 综合考虑了不同业务类型的服务质量需求,根据用户的信道条件、吞吐量和队列状
态确定调度优先级;结合用户信道的空间相关性进行用户选择、功率分配和比特加载. 通过
充分利用空、时、频多用户分集增益,在保证实时业务最小时延要求和非实时业务最小速率
要求的同时,最大化系统的吞吐量. 仿真结果说明,所提算法在系统吞吐量、丢包率及最
小速率满足率方面得到了改善.     

基于格基约减的多天线预编码处理机制

针对闭环多天线系统提出一种基于格基约减（LR）的预编码处理机制. 接收端对估计出的信道衰落矩阵进行LR量化处理,并向发送端反馈量化信息;发送端据此对发送信号进行预编码. 该机制一方面可以使得接收端线性检测,即获得满分集;另一方面,可使等效信道的多个子链路性能接近,避免发送端进行多次调制编码方式选择,有效降低系统复杂度. 仿真结果表明,基于LR的预编码在系统吞吐量性能上优于现有的相同码本大小的预编码方案,在信噪比为16dB时,吞吐量的增益为28%.     

认知双向中继网络下分布式鲁棒波束成形

针对认知双向中继网络下信道状态信息不理想的情况,提出了基于信干噪比(SINR)平衡的分布式鲁棒波束成形算法. 该算法的最优波束成形因子在满足中继总功率和主用户接收端干扰功率受限的条件下,使认知用户在最差情况下的SINR最大化. 通过使用S-Procedure,并引入半正定松弛思想,可将原优化问题转化为凸优化可行性问题进行求解. 仿真结果表明,该算法可有效降低认知用户对主用户接收端的干扰,保证主用户的正常通信,验证了该算法的有效性和鲁棒性.     

An approach for concurrent evaluation of technical and social aspects of software development methodologies

The paper presents an approach for evaluation of software development methodologies (SDM) that considers the aspects of a SDM’s social adoption and technical efficiency. It builds on existing evaluation models used in the field of SDM. Case study approach was used to validate the model in four software development organisations. In all four cases the management confirmed that the model provided valuable new insights into adoption and efficiency of the companies’ SDM.     

A novel terminal-controlled handover scheme in heterogeneous wireless networks

In the next generation heterogeneous wireless networks, a mobile terminal (MT) with a multi-interface may have network access from different service providers using various technologies. In spite of this heterogeneity, seamless intersystem mobility is a mandatory requirement. One of the major challenges for seamless mobility is the creation of a vertical handover scheme, which is for users that move between different types of networks. In this article a seamless mobility handover scheme is presented. The novelty of the proposed scheme is that handover is fully controlled by the terminal. To improve the performance of the proposed handover scheme, a network discovery algorithm with fuzzy logic and a handover decision algorithm using multi criteria decision making (MCDM) based on vague sets are derived, which are both user-centric. With these algorithms, the handover scheme is power-saving, cost-aware, and performance-aware. Simulation results show that the novel handover scheme can perform network discovery in time to reduce handover dropping rate and present unnecessary activation of its interface to save the battery power, while effectively choose the optimum network through making trade-off among the user preference, network condition, and system performance.     

Microwave noise modeling for PHEMT using artificial neural network technique

An improved noise model for pseudomorphic high electron mobility transistors (PHEMT) based on the combination of the artificial neural network (ANN) and conventional equivalent circuit modeling technique is presented. The frequency dispersion of the gate noise model parameter P, drain noise model parameter R, and the correlation coefficient C have been taken into account by using an ANN model. The influence of the gate leakage current can be accommodated by using the proposed noise model. The noise model parameters are determined directly from on wafer noise parameters measurement based on the noise correlation matrix technique. Good prediction for noise parameters and significant improvements of the accuracy of noise parameters are obtained up to 26 GHz for 2 × 40 μm gate width (number of gate fingers × unit gate width) 0.25 μm Double Heterojunction δ‐doped PHEMTs over a wide range of bias points. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

Experimental investigation of MIMO relay channels statistics and capacity based on wideband outdoor measurements at 2.35 GHz

Relay,which serves to enhance the performance of future communication networks,is one of the most promising techniques for IMT-Advanced systems.The potential performance improvement of relay is investigated in this work.Our investigation consists of two steps.In the first step,to obtain a better understanding of the fundamental properties of relay channels,we conducted outdoor measurements at 2.35 GHz with 50 MHz bandwidth in a typical urban area of China.Three links constituting the relay transmission,i.e....     

Ergodic Capacity Analysis and Adaptive Transsmion Scheme in Multi-user Distributed Antenna Systems

This paper focuses on analyzing the ergodic capacity performance of limited feedback (LFB) beamforming in multi-user distributed antenna system (DAS). In such a system, multi-user interference (MUI) is inevitably due to the channel uncertainties caused by quantization error. Considering this, we propose a parameter named effective ergodic capacity rate (EECR), which denotes the capacity offset between finite rate feedback and perfect channel state information (CSI). The simulation results show that the derived approximated EECR is very tight to actual EECR. Based on the approximated EECR, an adaptive minimum bit feedback scheme is proposed, which can effectively reduce the overhead of feedback channel and the complexity of the system. The simulation results verify the effectiveness of the proposed scheme.     

Asymptotic analysis for transmission capacity of wireless Ad-hoc networks

This article puts forward a new solution to the bound of the outage probability and transmission capacity of Ad-hoc networks. For the proofs of the upper and lower bounds are too complex, a much easier way is introduced to get the same results, and by using Taylor series, the asymptotic bound is derived. By comparing with the simulation results, we found that the asymptotic bound is sufficient accurate when the network parameters are selected properly, and is tighter than the upper and lower bounds.