This letter addresses adaptive channel estimation for OFDM systems to reduce computational complexity. There are numerous methods suggested for low-complexity channel estimation, but some of them still suffer from a considerable complexity or performance degradation due to the channel energy leakage. We present an adaptive channel estimator based on the channel impulse response (CIR) length estimate to reduce the complexity without any performance degradation. We first introduce a simple and efficient method based on the sequential hypothesis test (SHT) to estimate the CIR length and then apply it to the adaptive implementation of the SVD-based LMMSE estimator. Simulation results demonstrate that the SHT method performs well with very low complexity and that the adaptive estimator not only reduces the complexity significantly but also provides better performance than the fixed estimators.

中文翻译：

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使用 CIR 长度估计的 OFDM 系统自适应信道估计

这封信解决了 OFDM 系统的自适应信道估计，以降低计算复杂度。有许多方法建议用于低复杂度信道估计，但由于信道能量泄漏，其中一些方法仍然存在相当大的复杂性或性能下降。我们提出了一种基于信道脉冲响应 (CIR) 长度估计的自适应信道估计器，以在不降低性能的情况下降低复杂性。我们首先介绍一种基于序列假设检验（SHT）的简单有效的方法来估计 CIR 长度，然后将其应用于基于 SVD 的 LMMSE 估计器的自适应实现。