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CDMA spectral efficiency refers to the system spectral efficiency in bit/s/Hz/site or Erlang/MHz/site that can be achieved in a certain CDMA based wireless communication system. CDMA techniques (also known as spread spectrum) are characterized by a very low link spectral efficiency in (bit/s)/Hz as compared to non-spread spectrum systems, but a comparable system spectral efficiency. The system spectral efficiency can be improved by radio resource management techniques, resulting in that a higher number of simultaneous calls and higher data rates can be achieved without adding more radio spectrum or more base station sites. This article is about radio resource management specifically for direct-sequence spread spectrum (DS-CDMA) based cellular systems. ==CDMA based standards== Examples of DS-CDMA based cellular systems are: * the 3GPP/UMTS 3G radio interfaces WCDMA, HSDPA and HSUPA used globally. * the 3GPP2 2G standard cdmaOne (IS-95) and 3G standards CDMA2000 1x and 1xEV-DO, used especially in the U.S. and South Korea * the Chinese TD-SCDMA system. The terminology used in this article is firstly based on 3GPP2 standards. CDMA is not expected to be used in 4G systems, and is not used in pre-4G systems such as LTE and WiMAX, but is about to be supplemented by more spectral efficient frequency-domain equalization (FDE) techniques such as OFDMA. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「CDMA spectral efficiency」の詳細全文を読む スポンサード リンク
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