关于移动WIMAX的调查毕业设计外文翻译.docxVIP

翻译原稿A Survey on Mobile WiMAXBo Li, Hong Kong University of Science and Technology YangQin and Chor Ping Low, Nanyang Technological UniversityChoon Lim Gwee, Republic PolytechnicABSTRACTThe IEEE 802.16 standard, commonly known as WiMA X, is t he latest technology that has pro mised to offer broadband wireless access over long distance. Since 2001 WiMAX has evolved from 802.16 to 802.16d for fixed wireless access, an d to the new IEEE 802.16e standard with mobility support. In this article we provide an overview of the s tat e- of -t h e-art mo bile WiMAX technology and its development .We mobile WiMAX specification.INTRODUCTIONIEEE 802.16, a solution to broadband wireless access (BWA) commo nly kn own as Worldw- ide Interoperability for Microwave Access (WiMAX), is a recent wireless broad- band standa- rd th at has promised high bandwidth over longran- ge transmission. The standard specifies the air interface, including the medium access control (MAC) and physical (PHY) layers, of BWA. The key dev- elopment in t he PHY layer includes orthogo nal fre-mu ltiple access is achi- eved by assigning a subset of subcarriers to each individual user. This res- embles cod e- division mult ip le acc ess (CDMA) spread spectrum in that it can provid e different qu ality of service (QoS ) f or eac h user; users achieve different data rates by as- signing different cod e spreading fact ors or diff erent numbers of spreading codes. In an OFDM system, the data is divided into mult ip le parallel subst reams at a transmitted on a separate orthogonal subcarrier. This increases symbol duration and improves system robustness. OFDM is achieved by providing mult ip lexin g on u sers’d at a st reams on both uplink and downlink transmissions.First published in 2001, the I EEE 802.16 standard specified a frequency range of 10–66 GHz with a theoretic al maximum band width of 120 Mb/s and maximum transmission range of 50 line-o f-sight (LOS) transmission an d thus does not seem to favor depl