A method of fuzzy preference relation to authorize the worldwide interoperability for microwave access license in Taiwan

This study proposes a preference relation based evaluation framework to help the National Communication Commission (NCC) in Taiwan authorize a worldwide interoperability for microwave access (WiMAX) license under a fuzzy environment where the uncertainty, subjectivity and vagueness are dealt with linguistic variables parameterized by triangular fuzzy numbers. This study applies the fuzzy multi-criteria decision making approach to determine the importance weights of evaluation criteria and consolidate the performance ratings of possible alternatives. Aggregated the evaluators’ opinions toward the criteria and alternatives, the fuzzy preference relation approach is utilized to obtain the non-dominated degree of each alternative for the decision makers to make a final decision. Simultaneously, an empirical case involving sixteen quantitative and fifteen qualitative evaluation criteria, thirteen telecommunication applicants assessed by twelve specialists from various fields of telecommunication industry in Taiwan is solicited to demonstrate the proposed approach.     

Efficient coupled PHY and MAC use of physical bursts by ARQ-enabled connections in WiMAX/IEEE 802.16e networks

In this paper we address an aspect of the mutual influence between the PHY layer budding blocks (FEC Blocks) and the MAC level allocations in the Uplink and Downlink of IEEE 802.16e/WiMAX networks. In these networks it is possible to transmit MAC level frames, denoted MAC PDUs, such that a PDU contains an integral number of fixed size Data Blocks. PDUs are transmitted over PHY Bursts, which are divided into FEC Blocks. We suggest several algorithms to compute the best way to define PDUs in a Burst in order to maximize several performance criteria. We also give guidelines on how to choose the best Modulation/Coding Scheme (MCS) to use in the Burst, given the SNR of the channel and the performance criteria.     

一种WiMAX上行可变步长功率的控制算法

功率控制技术是无线通信系统需实现的关键技术,根据IEEE802.16协议要求和WiMAX系统同频干扰特性,WiMAX系统上行链路需要一种合理的功率控制算法.因此,通过改进传统闭环功率控制算法,使得算法中功率控制步长可根据上行链路信道质量而改变,并由此得到一种应用于WiMAX系统上行链路的可变步长功率控制算法.最后通过仿真对比得到算法收敛因子的合理取值,验证了可变步长功率控制算法可有效提高功率控制精度和收敛速度.     

移动WIMAX安全问题分析

WIMAX(Worldwide Interoperability for Microwave Access),即全球微波互联接入。WiMAX的另一个名字是IEEE 802.16,讨论IEEE802.16e(Mobile WiMAX)标准,主要分析WiMAX的3个方面安全隐患、没有认证保护的管理消息、未加密的管理消息以及多播广播中的共享公钥问题。同时提出一些     

Cost-effective radio over fiber system for multi service wireless signal

The feasibility of the simultaneous transmission of several wireless signals over a cost-effective Radio over Fiber (RoF) link is investigated. A RoF link simulation tool is presented and applied to validate the experimental results in the case of the transmission of two wireless signals, one compliant to Universal Mobile Telecommunications Service (UMTS) and one to Worldwide Interoperability for Microwave Access (WiMAX) standards. The cross-talk between the transmitted signals is showed and related to the RoF transmitter's characteristic in terms of frequency chirping. Both for uplink and downlink of the wireless signal RoF distribution system practical design aspects are finally evidenced.     

利用OFDMA进行资源分配的投机算法

正交频分复用OFDM(Orthogonal Frequency Division Multiplexing)系统以其优良的对抗频率选择性衰落和信号码间串扰的能力,被看作是Beyond 3G移动通信的主要技术.IEEE802.16工作组将OFDM和OFDMA(Orthogonal Frequency Division Multiple Accessing)作为802.16d/e的物理层选择.802.16e重点采用OFDMA来保证移动性,它的物理层可以支持四种不同的子载波数量,信号带宽与子载波数量成正比,这就可以在移动环境中灵活适应信道带宽的变化.本文对单蜂窝系统中下行链路的资源分配(包括子载波的分配和功率的分配)进行了研究探讨,提出了一个投机算法,目的是最大化系统的瞬时数据吞吐量.     

ONU型网关融合接口的设计和实现

【】网关型ONU作为网关及PON技术的融合,不仅保持了PON原有的管理方式,还支持运营商实现远端管理。PON系统具有高带宽和低成本等优势。在ONU网关上开发融合无线接口,可以在支持传统有线业务的基础上,丰富光纤系统的接口种类。既保持原有优势,又增加系统的无线资源。传统的方法是在有线接入设备上开通无线接入通道,不能实现集中控制和管理。针对现有技术的不足,提出了新的设计方法,采用基于FPGA和嵌入式处理器的方法。进一步给出了详细的实现过程。测试验证表明该设计比原有方案有优势。     

Enabling Optical Network Test Bed for 5G Tests

In this work, we show some experimental approaches concerning optical network design dedicated to 5G infrastructures. In particular, we show some implementations of network slicing based on Carrier Ethernet forwarding, which will be very suitable in the context of 5G heterogeneous networks, especially looking at services for vertical enterprises. We also show how to adopt a central unit (orchestrator) to automatically manage such logical paths according to quality-of-service requirements, which can be monitored at the user location. We also illustrate how novel all-optical processes, such as the ones based on all-optical wavelength conversion, can be used for multicasting, enabling development of TV broadcasting based on 4G–5G terminals. These managing and forwarding techniques, operating on optical links, are tested in a wireless environment on Wi-Fi cells and emulating LTE and WiMAX systems by means of the NS-3 code.     

Design Validation of UWB MIMO Antenna with Enhanced Isolation and Novel Strips for Stop-Band Characteristics

This article introduces a novel Ultra Wide Band (UWB) Multiple Input Multiple Output (MIMO) antenna with Triple-band notched characteristics. The overall dimensions of the antenna are 18 × 34 mm². The designed antenna has two similar flower-shaped radiators with L-shape strips, common ground with two flag-shaped decoupling stubs and T-shape strips for notched band characteristics. Two flag-shaped stubs are used to achieve 22 dB improved isolation. The S₁₁ of the designed antenna is less than −10 dB between 3.07 GHz and 12.40 GHz, having various stopped bands of WiMAX, WLAN and X bands. The presented antenna is examined and investigated in terms of S-parameters, Mutual Coupling, Gain, Envelope Correlation Coefficient (ECC), Efficiency and Diversity Gain (DG).     

基于嵌入式平台802.16 AES-CCM算法的优化及实现

通过深入分析AES-CCM算法原理,对AES算法中运算量最大的轮变化过程进行优化,将轮变化中的4个步骤转变为查表和异或运算,进一步简化了算法的执行过程;并对802.16协议中CCM模式应用规则存在的安全隐患提出了改进措施,增强了算法在抗重放攻击方面的能力.通过在富士通3400 WiMAX开发板＂ARM＋VxWorks＂平台下设计和实现了采用AES-CCM算法的数据传输加密方案,最后采用应用模块对算法进行测试,结果表明了改进后算法模块的正确性和有效性.