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对于从事商务、娱乐和社会网络应用的用户而言,网络数据和信息服务接入的重要性在日益显现。处于完全运动状态的用户,更希望高速、可靠、高质量地接入到这些无所不在的信息服务网络中。本文描述了IEEE802.20标准,它能满足高速数据服务的要求,同时又支持用户充分的移动性。它是一个在移动环境中能提供(基于IP)最佳宽带无线互联网接入的标准。与以前没有使用这种优化的网络标准相比,它能向网络运营商提供具有更高性能(如较高数据传输速率和较低延迟)以及更低运营成本的网络。该标准包括了正交频分复用(OFDM)宽带模式和625k多载波模式。这两种模式都支持时分双工(TDD)工作方式,而频分双工(FDD)只能被正交频分复用宽带模式支持。这两种模式都被设计成具有支持全范围的QoS的属性,因而使这种技术很适合支持具有低时延和低抖动要求的实时流服务以及接近实时的数据服务。在这两种情况下,低误差率与时延可以做到平衡处理。802.20标准的这些特性,能很好地满足21世纪用户对无线移动接入的要求。
The importance of accessing network data and information services is increasingly apparent to users engaged in business, entertainment and social networking applications. Users in full motion prefer the high-speed, reliable and high-quality access to these ubiquitous information service networks. This article describes the IEEE 802.20 standard, which meets the requirements of high-speed data services while supporting the full mobility of users. It is a standard that offers (IP-based) best broadband wireless Internet access in a mobile environment. It offers network operators a network that offers higher performance (such as higher data rates and lower latency) and lower operating costs than previously unoptimized network standards. The standard includes orthogonal frequency division multiplexing (OFDM) broadband mode and 625k multi-carrier mode. Both modes support the time division duplexing (TDD) mode of operation, while the frequency division duplexing (FDD) can only be supported by the orthogonal frequency division multiplexing wideband mode. Both of these modes are designed with attributes that support a full range of QoS, making this technology well suited for supporting real-time streaming services with low latency and low jitter requirements as well as near-real-time data services. In both cases, low error rates and delays can be balanced. These features of the 802.20 standard fit well with 21st century users’ demands for wireless mobile access.