专业英语论文.doc

文档介绍：worksincreaseinpopularityandpervasiveness,,radiolinktransfer,,second-andthird-generationmobilesystemsdependedontheemploymentoftheradiospectrumthatwaseitherunlicensed(availableforpublicuse)(terminals)(4G)putingthroughseamlessmobility[1].Eventhough4Giscurrentlyundefined,,4Gwillhavelargerbandwidth,higherdatarates,smootherandquickerhandoff,(intra-system)andvertical(intersystem)handoffaswellasseamlessmobility,qualityofservice,dependability,,,handoffsmustexhibitlowlatency,sustainminimalamountsofdataloss,,works(WWANs),works,suchaswirelessLANs(WLANs),