非周期擴(kuò)頻的同步CDMA系統(tǒng)下行信道的分?jǐn)?shù)階間隔信道估計(jì)
Fractionally Spaced Channel Estimation for Synchronous DS-CDMA Downlink with Aperiodic Spreading Code
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摘要: 使用正交擴(kuò)頻碼的同步CDMA系統(tǒng)具有對(duì)抗同信道干擾的能力，但是多徑傳播導(dǎo)致信號(hào)失去正交性，互相關(guān)值增加。在這些情況下，需要對(duì)信道進(jìn)行估計(jì)以提高接收機(jī)檢測(cè)性能。以往的基于子空間的CDMA信道估計(jì)算法都是在chip速率采樣的基礎(chǔ)上得到的，其條件是接收信號(hào)滿足Nyquist定理且信道是最小相位系統(tǒng)，這些條件在實(shí)際情況中是很難滿足的。該文提出一種應(yīng)用于非周期擴(kuò)頻的同步CDMA系統(tǒng)的下行信道的分?jǐn)?shù)階間隔信道估計(jì)的算法。計(jì)算機(jī)仿真表明了算法是有效的。Abstract: Synchronous Code-Division Multiple-Access (CDMA) techniques possess intrinsic protection against co-channel interference when orthogonal codes are used. However, in the presence of multipath propagation, the signals lose their orthogonality property, leading to increased cross correlation. In these cases, channel estimation may be needed in order to improve detection. The former algorithms for estimating the channel response of CDMA system are used for signal sampled with chip rate. The received signal sampled in chip rate does not satisfy the Nyquist theory and the channel may be not a minimumphase system that the former algorithms do not work. An algorithm for fractionally spaced channel estimation of a synchronous CDMA system is proposed that uses aperiodic spreading code. Simulations demonstrate the performance of proposed algorithm.
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