共查询到20条相似文献,搜索用时 156 毫秒
1.
1999年,IEEE成立了802.16211作组专门从事宽带无线接入标准的研究,到目前为止相继发布了IEEE802.16、IEEE802.16a、IEEE802.16d、IEEE802.16e等一系列的技术标准。IEEE802.16d对IEEE802.16和IEEE802.16a进行了整合和修订,是一项固定宽带无线接入技术的标准,主要用于固定、游牧等场景。而IEEE802.16e是基于IEEE802.16d标准的, 相似文献
2.
LDPC码由于其接近香农限的性能近年来引起了人们的广泛关注:IEEE802.16a采用OFDM(正交频分复用)作为物理层调制标准技术,是第二代无线城域网(WMAN:Wireless Metropolitan Area Network)空中接口协议IEEE802.16的修正版。介绍了LDPC码的线性编码和LLR BP译码算法.并在IEEE802.16a协议规定的环境下进行了仿真? 相似文献
3.
WiMAX技术是目前国际上影响力最大的宽带无线接入技术,该技术基于IEEE802.16空中接口,而WiMAX是IEEE802.16技术在市场推广中采用的名称。IEEE802.16标准的空中接口包括IEEE802.16d(802.16-2004)和IEEE802.16e(802.16-2005)两个空中接口规范,前者是固定宽带无线接入系统空中接口规范(频段:10GHz-66GHzN〈11GHZ),[第一段] 相似文献
4.
5.
6.
7.
以IEEE802.16d-2004,IEEE802.16e-2005和IEEE802.16Corrigendum2的Draft3.0为基础文稿分析了IEEE802.16e-2005协议描述的PowerControl,目的是希望对16e的PowerControl机制进行一个比较系统的描述总结。 相似文献
8.
IEEE 802.16和WiMax的组网技术 总被引:3,自引:0,他引:3
如何提高网络资源利用率和网络传输效率是无线通信领域面临的难题。作为宽带无线接入系统的标准,IEEE802,16在物理层采用正交频分复用技术和灵活的编码调制方式采提高传输速度和性能;在MAC层采用预约与竞争相结合的调度机制,以连接、服务流等与服务质量(QoS)相关的概念为基础。在入网与初始化、帧结构设计上优化设计,提高网络吞吐量,降低网络时延,使网络配置更加灵活。WiMAX基于IEEE802.16技术标准。采用点对多点(PMP)方式实现灵活组网,是宽带无线接入系统的典型血用技术。 相似文献
9.
10.
一、什么是WiMAX WiMAX(Worldwide Interoperability for Microwave Access)是定点宽带无线MAN(城域网)技术。WiMAX通常是指IEEE802.16a标准(2GHz~11GHz)。该技术是IEEE(电气电子工程师协会)于2002年4月发布的工作于10GHz至66GHz频段下的IEEE802.16标准的扩展,是针对微波和毫米波频段提出的一种新型空中接口标准。此外,也可以理解为是WiMAX论坛极力推介的IEEE802.16系列标准(目前有802.16a,802.16d,及802.16e等)。 WiMAX研发的目标是打算在MAN范围内提供一种性能可与Cable modem、DSL等基于线缆的宽带接入相竞争的,工作在10GHz到66GHz(现下频段已延伸到2GHz)频段的最后一千米的宽带接入技术。典型的802.16a通常由安装在建筑物上的基站和家庭 相似文献
11.
12.
Kee-Bong Song Ekbal A. Seong Taek Chung Cioffi J.M. 《Wireless Communications, IEEE Transactions on》2006,5(7):1685-1694
This paper proposes adaptive modulation and coding (AMC) as a method for the bit-interleaved coded OFDM (BIC-OFDM) packet transmission. Following a pair-wise error probability (PEP) analysis of AMC-BIC-OFDM in a slowly fading frequency selective channel, AMC scheme maximizes the total rate by optimally selecting the code and efficiently allocating rate and power over the frequency band. The proposed method improves upon the performance of uniform rate and power allocation scheme by 6.5 to 10 dB 相似文献
13.
14.
Reed-Solomon(RS)码是IEEE 802.16d标准中信道编码的重要组成部分。通过对标准中RS码特点的分析,对传统的RS译码器进行改进,提出了一种适用于该标准的RS译码方法。利用循环码的性质,改进伴随式计算模块,减少延迟时间;利用RS码中已知删除位置的特点,简化删除位置多项式计算电路;通过对RS码实际应用环境的分析,减少利用迭代方法解关键方程时所需的基本单元数目。最终利用Verilog语言实现硬件电路,在FPGA上验证通过并应用于WiMAX802.16d系统。 相似文献
15.
16.
为了研究无线光通信中数字脉冲调制与信道编码的联合编码调制问题,在给出调制时域结构的基础上,采用理论推导和数值仿真相结合的方法,分析了基于二进制线性分组码的开关键控、数字脉冲位置调制和数字脉冲间隔调制系统的差错性能,得出了信道编码纠错能力与调制阶数的结合关系。结果表明,采用开关键控调制的系统,其汉明距离与欧式距离等价,故不存在调制与信道编码参量匹配问题;脉冲位置调制系统在纠错个数大于调制阶数时,可取得较明显的编码调制增益,当纠错个数能被调制阶数整除时,编码和调制达到匹配;由于数字脉冲间隔调制的符号时隙不固定,存在错误传播现象,不宜与差错编码联合使用。所得结果可为无线光通信链路的设计提供参考。 相似文献
17.
In IEEE 802.16 networks, a subscriber station (SS) could be a single mobile user, a residence house, or an office building providing Internet service for multiple customers. Considering the heterogeneity among SSs which have diverse traffic demands, in this paper, we introduce the weighted proportional fair (WPF) scheduling scheme for the Best Effort (BE) service in IEEE 802.16 networks to achieve the flexible and efficient resource allocation. We develop an analytical model to investigate the performance of WPF in terms of spectral efficiency, throughput, resource utilization, and fairness, where the Rayleigh fading channel and the adaptive modulation and coding (AMC) technique are considered. Extensive simulations are conducted to illustrate the efficiency of the WPF scheduling scheme and verify the accuracy of the analytical model. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
18.
Soo-Yong Jeon Dong-Ho Cho 《Communications Letters, IEEE》2006,10(6):459-461
HSDPA (high-speed downlink packet access) is an evolved UMTS packet scheme that delivers increased user peak data rates and quality of service. A key technique supporting HSDPA is adaptive modulation and coding (AMC), in which the modulation scheme and the coding rate are changed adaptively according to the downlink channel quality reported by the user equipment (UE). Therefore, the channel quality indication (CQI) reporting scheme is directly related to the accuracy of AMC and the performance of HSDPA. This letter proposes channel adaptive CQI reporting schemes in which UEs report the CQI value intelligently by using information about channel quality. With the proposed schemes, the battery capacity of UE can be conserved and the uplink interference can be lowered by filtering off redundant CQI reports or the transmission error rate can be lowered by fast CQI reports. 相似文献
19.
IEE 802.16标准在物理层定义了多种可选的调制和编码方式,并可采用基于信道状态信息的自适应调制编码机制。本文提出一种新的适用于全球微波接入互操作网络的信噪比阈值区间可变式自适应调制编码机制,其自适应调制-编码模式不仅取决于物理层信道状态信息,还与高层多媒体服务流的目标误包率这一重要服务质量参数有关。与传统型和改进型自适应调制编码机制相比,信噪比阈值区间可变式自适应调制编码机制能够在满足各类业务目标误包率的同时获得较好的系统有效数据传输速率。 相似文献
20.
In this paper, we develop a novel framework for analyzing radio link level performance for opportunistic scheduling with automatic repeat request (ARQ)-based error control in multi-rate wireless networks. The multi-rate transmission is assumed to be achieved through adaptive modulation and coding (AMC) to adjust the transmission rate according to the channel condition. The residual error effect due to each AMC setting is counteracted by means of a limited persistence ARQ protocol. The novelty of the proposed analytical framework lies in the fact that we are able to derive complete statistics (in terms of probability mass function) for both short-term and long-term performance measures such as system throughput, per-flow throughput, inter-success delay under both uncorrelated and correlated wireless channels. These performance measures can also be obtained in case of non-identical channels for different users. Analytical results are validated through simulations and the impacts of channel behavior on the different radio link level performance metrics are investigated. 相似文献