Downlink Transmit Power Allocation in Soft Fractional Frequency Reuse Systems

Downlink transmit power allocation schemes are proposed for soft fractional frequency reuse (FFR) in loose and tightly coordinated systems. The transmit powers are allocated so that the loss of spectral efficiency from the soft FFR is minimized, and the required cell edge user throughput is guaranteed. The effect of the soft FFR on spectral efficiency is evaluated depending on the power allocation schemes and the number of subbands. Results show that the loss of spectral efficiency from the soft FFR can be reduced by configuring an appropriate number of subbands in the loosely coordinated systems. In tightly coordinated systems, results show that the loss of spectral efficiency can be minimized regardless of the number of subbands due to its fast coordination.     

Application of Adaptive Neuro-Fuzzy Inference System for Interference Management in Heterogeneous Network

Femtocell (FC) technology envisaged as a cost-effective approach to attain better indoor coverage of mobile voice and data service. Deployment of FCs over macrocell forms a heterogeneous network. In urban areas, the key factor limits the successful deployment of FCs is inter-cell interference (ICI), which severely affects the performance of victim users. Autonomous FC transmission power setting is one straightforward way for coordinating ICI in the downlink. Application of intelligent control using soft computing techniques has not yet explored well for wireless networks. In this work, autonomous FC transmission power setting strategy using Adaptive Neuro Fuzzy Inference System is proposed. The main advantage of the proposed method is zero signaling overhead, reduced computational complexity and bare minimum delay in performing power setting of FC base station because only the periodic channel measurement reports fed back by the user equipment are needed. System level simulation results validate the effectiveness of the proposed method by providing much better throughput, even under high interference activation scenario and cell edge users can be prevented from going outage.     

Coexistence of OFDM‐Based IMT‐Advanced and FM Broadcasting Systems

Coexistence analysis is extremely important in examining the possibility for spectrum sharing between orthogonal frequency‐division multiplexing (OFDM)‐based international mobile telecommunications (IMT)‐Advanced and other wireless services. In this letter, a new closed form method is derived based on power spectral density analysis in order to analyze the coexistence of OFDM‐based IMT‐Advanced systems and broadcasting frequency modulation (FM) systems. The proposed method evaluates more exact interference power of IMT‐Advanced systems in FM broadcasting systems than the advanced minimum coupling loss (A‐MCL) method. Numerical results show that the interference power is 1.3 dB and 3 dB less than that obtained using the A‐MCL method at cochannel and adjacent channel, respectively. This reduces the minimum separation distance between the two systems, which eventually saves spectrum resources.     

Modelling of short‐term frequency scaling for rain attenuation using ITALSAT data

In this article we describe a statistical model for the assessment of the short‐term frequency scaling ratio between rain attenuations at cm and mm wavelengths, taking into consideration the fluctuations arising from the type of rain (mainly the raindrop size distribution). The model has been derived from measured data, using the large attenuation database collected in Spino d'Adda, Italy, during the ITALSAT 8‐years experiment at 18.7, 39.6 and 49.5 GHz, but can be applied to any pair of frequencies. By applying the model it is possible to generate, by means of a generator of random Gaussian numbers, samples of the up‐link attenuation, for a given down link attenuation, to be employed in the simulation of up‐link power control (ULPC) slant path channels. Copyright © 2006 John Wiley & Sons, Ltd.     

Optimization of Power Control Function for Downlink

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Uplink Power Control for MIMO-OFDMA Cellular Systems

In this paper, we propose a novel uplink power control algorithm, SMST, for multiple-input multiple-output orthogonal frequency-division multiple access (MIMO-OFDMA).We perform an extensive system-level simulation to compare different uplink power control algorithms, including the FPC adopted in 3GPP LTE and LTE-Advanced. Simulations show that SMST adopted in IEEE 802.16m outperforms other algorithms in terms of spectral efficiency, cell-edge performance, interference control, and trade-off control between sector-accumulated throughput and cell-edge user throughput. The SMST performance gain over FPC can be more than 40%.     

上行多用户MIMO系统的功率控制

多用户多输入多输出技术会带来系统干扰噪声比变大。功率控制技术可以很好地抑制小区间干扰和提高扇区吞吐量。首先介绍经典功率控制方案,在此基础上提出改进,以降低系统平均IoT值并保证5%边缘用户频谱效率。通过仿真,给出了用户功率调整参数,在系统吞吐量和小区干扰水平之间取得最佳折中。     

微机模糊控制在功率电子学中的应用

针对市用交流电网电压不稳定，以致一般的负载很难在其额定电压下工作，本文提出了把微机模糊逻辑控制应用于功率电子学领域的交流稳压调压系统．通过对晶闸管导通角的模糊控制以达到控制各种负载不同的额定电压的目的。用该方法实现的稳压调压系统为微机模糊控制在功率电子学中的应用提供了一种新的思路。     

Adaptive Data Transmission Control for Multilane‐Based Ethernet

We propose a reconciliation sublayer (RS)‐based lane and traffic control protocol for energy‐efficient 40‐G/100‐G Ethernet. The RS performs active/inactive lane control and data rate adaptation depending on active lane information received from the upper layer. This protocol does not result in a processing delay in the media access control layer, nor is an additional buffer required at the physical layer for dynamic lane control. It ensures minimal delay and no overhead for the exchange of control frames and provides a simple adaptive data rate.     

Double Gate MOSFET Modeling Based on Adaptive Neuro‐Fuzzy Inference System for Nanoscale Circuit Simulation

As the conventional silicon metal‐oxide‐semiconductor field‐effect transistor (MOSFET) approaches its scaling limits, quantum mechanical effects are expected to become more and more important. Accurate quantum transport simulators are required to explore the essential device physics as a design aid. However, because of the complexity of the analysis, it has been necessary to simulate the quantum mechanical model with high speed and accuracy. In this paper, the modeling of double gate MOSFET based on an adaptive neuro‐fuzzy inference system (ANFIS) is presented. The ANFIS model reduces the computational time while keeping the accuracy of physics‐based models, like non‐equilibrium Green's function formalism. Finally, we import the ANFIS model into the circuit simulator software as a subcircuit. The results show that the compact model based on ANFIS is an efficient tool for the simulation of nanoscale circuits.     

基于改进自适应协同控制方法的电力系统混沌控制

针对4阶混沌电力系统,该文提出一种具有快速收敛特性的自适应协同控制方案。首先基于Lyapunov稳定性定理和全局快速收敛理论,设计了一种具有快速收敛特性的协同控制器,该控制器可使宏变量快速到达不变流形并可以得到平滑无抖振的控制输入,实现宏变量的精确收敛。然后将所设计的控制器应用于4阶电力系统的混沌控制中。由于电力系统中的能量过剩会引起混沌振荡,在控制回路中引入储能装置,通过控制储能装置吸收电力系统中多余的有功功率来抑制其混沌振荡。在此基础上通过设计自适应律,消除了控制器设计过程中出现的复杂项,增加了控制器的实用性。最后通过数值仿真,验证了该控制方案的有效性与优越性。     

GPRS中的一种下行功率控制算法及其改进

通用分组无线业务GPRS是覆盖于GSM移动通信网之上的分组交换数据网络。提出了一种基于载干比C/I的下行功率控制算法。在此基础上,根据载干比C/I与误码率BER的函数关系,提出一种基于误码率的下行功率控制算法。最后,通过使用基于MLD平台设计的仿真软件,分析比较了这两种算法对系统性能的改善。     

Rainfall propagation impairments for medium elevation angle satellite‐to‐earth 12 GHz in the tropics

Rain attenuation is the dominant propagation impairment for satellite communication systems operating at frequencies above about 10 GHz. The rainfall path attenuation at 12.255 GHz measured at Universiti Sains Malaysia (USM) for 4 years (2 January to 5 December) is presented. This paper presents an empirical analysis of rain rate and rain attenuation cumulative distribution functions obtained using 1‐min integrated rainfall data and comparison of the measured data with data obtained from well‐established rain model attenuation predictions. Copyright © 2008 John Wiley & Sons, Ltd.     

认知无线电中一种基于干扰温度的功率控制算法

基于干扰温度模型,应将认知无线电网络中认知用户与主用户共享频谱时应满足各自的用户服务质量（QoS）问题转化为有约束的非线性功率控制优化问题。运用迭代算法和拉格朗日相关理论探讨出一种近似最优的功率分配算法。理论分析和仿真表明,该算法既能满足主用户的干扰温度容限,同时又能使认知用户获得很好的信噪干扰比,增大系统的吞吐量。     

Reduce‐complexity fuzzy‐inference‐based iterative multiuser detection for wireless communication systems

In recent years, combining multiuser detection and intelligence computer scheme have received considerable attention. In this paper, adaptive fuzzy‐inference multistage matrix wiener filtering (FI‐MMWF) techniques, based on the minimum mean‐square error criterion, are proposed for ultra‐wideband (UWB) impulse radio communication systems. These FI‐MMWF‐based algorithms employ a time‐varying fuzzy‐inference‐controlled filter stage. Consequently, the proposed approaches accomplish a substantial saving in complexity without trading off the system performance and dynamic‐tracking characteristic. In addition, the fuzzy‐logic‐controlled matrix conjugate gradient algorithm is adopted to reduce the system complexity without trading off the bit‐error‐rate (BER). Simulations are conducted to evaluate the convergence and tracking behavior of the proposed MMWF algorithm, and the BER of the time‐hopping‐UWB system in a realistic UWB channel is investigated. Copyright © 2011 John Wiley & Sons, Ltd.     

电力系统提高电能质量的方法研究

电能质量对于电力系统的生产效率及电能的上网传输十分重要,文章在分析电能质量诸多影响因素的基础上,对提高电能质量的方法展开探讨,给出了具体提高电能质量的方法与措施,有助于进一步提高电力系统电能生产质量。     

A model for the estimation of the carrier‐to‐noise plus total interference ratio between two adjacent dual polarized satellite links sharing the same frequency band

In modern satellite communications, matters such as frequency congestion, transmission of dual polarized carriers and increase of the number of geostationary satellites in use, necessitate the implementation of interference analysis in neighbouring networks so as to ensure satisfactory quality of service. In this paper, a recently proposed model for the prediction of the degradation of the carrier‐to‐interference ratio due to differential rain attenuation and cross‐polarization, which is applicable only for the noise‐dominant case, has been properly modified to include the general case. The proposed model is based on the lognormal assumption for the point rainfall rate statistics and the convective raincell model. Due to complexity of the proposed analysis, some simple regression‐derived formulas have been generated forming a very useful tool for the system engineer. The elaborations of numerical results examine the influence of various parameters upon the total availability performance and the optimum utilization of the geostationary orbit. Copyright © 2005 John Wiley & Sons, Ltd.     

Energy‐Efficiency Power Allocation for Cognitive Radio MIMO‐OFDM Systems

This paper studies energy‐efficiency (EE) power allocation for cognitive radio MIMO‐OFDM systems. Our aim is to minimize energy efficiency, measured by “Joule per bit” metric, while maintaining the minimal rate requirement of a secondary user under a total power constraint and mutual interference power constraints. However, since the formulated EE problem in this paper is non‐convex, it is difficult to solve directly in general. To make it solvable, firstly we transform the original problem into an equivalent convex optimization problem via fractional programming. Then, the equivalent convex optimization problem is solved by a sequential quadratic programming algorithm. Finally, a new iterative energy‐ efficiency power allocation algorithm is presented. Numerical results show that the proposed method can obtain better EE performance than the maximizing capacity algorithm.     

Adaptive Standby Mode Scheduling Method Based on Analysis of Activation Pattern for Improving User Experience of Low‐Power Set‐Top Boxes

The lowest power mode (passive‐standby mode) was proposed for reducing the power consumption of set‐top boxes in a standby state when not receiving content. However, low‐power set‐top boxes equipped with the lowest power mode have been rarely commercialized because of their low‐quality user experience. In the lowest power mode, they deactivates almost all of operational modules and processes, and thus require dozens of seconds for activation latency (that is, the latency for activating all modules of the set‐top boxes in a standby state). They are not even updated in a standby state because they deactivate their network interfaces in a standby state. This paper proposes an adaptive standby mode scheduling method for improving the user experience of such boxes. Set‐top boxes using the proposed method can analyze the activation pattern and find the frequently used time period (that is, when the set‐top boxes are frequently activated). They prepare for their activation during this frequently used time period, thereby reducing the activation latency and enabling their update in a standby state.     

网络控制系统建模与控制

数据总线传输方案能够有效克服传统通信的弊端,但由于信息传输分时复用通信总线,系统时延不可避免。时延不但会降低网络控制系统的控制性能,而且还是引起系统不稳定的潜在因素。从网络时延这一问题出发,对网络控制系统的建模方法进行了分析研究,并基于此提出利用模糊控制来补偿系统时延影响。该方法通过模糊控制调节PID控制器输出,从而改善系统性能。最后通过仿真实例验证了上述方法的有效性。