Channel estimation in OFDM systems with unknown interference
Channel estimation in OFDM systems with unknown interference
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DOI：
10.1109/twc.2009.090270
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发表时间：
2009-10
影响因子：
10.4
通讯作者：
M. Morelli;M. Moretti
中科院分区：
文献类型：
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作者：
M. Morelli;M. Moretti
研究了在未知窄带干扰（NBI）下正交频分复用（OFDM）系统的信道估计问题。这种场景出现在许多实际环境中，包括蜂窝应用和新兴的频谱共享系统，其中不同类型的无线服务在相同频带上的共存可能导致显著的同信道干扰。为传统OFDM传输设计的估计算法预计将遭受NBI存在下的显着性能下降。为了克服这个困难，在本工作中，我们遵循一种新的导频辅助的方法，每个导频子载波上的干扰功率被视为一个滋扰参数，这是平均从相应的似然函数。然后根据期望最大化（EM）原理或通过应用雅可比-牛顿算法以迭代方式使后者最大化。由此产生的方案具有负担得起的复杂性，并且对NBI具有固有的鲁棒性。通过计算机模拟研究了它们的精度，并与相关的Cramer-Rao界进行了比较.
We investigate the problem of channel estimation in an orthogonal frequency-division multiplexing (OFDM) system plagued by unknown narrowband interference (NBI). Such scenario arises in many practical contexts, including cellular applications and emerging spectrum sharing systems, where coexistence of different types of wireless services over the same frequency band may result into remarkable co-channel interference. Estimation algorithms devised for conventional OFDM transmissions are expected to suffer from significant performance degradation in the presence of NBI. To overcome this difficulty, in the present work we follow a novel pilot-aided approach where the interference power on each pilot subcarrier is treated as a nuisance parameter which is averaged out from the corresponding likelihood function. The latter is then maximized in an iterative fashion according to the expectation-maximization (EM) principle or by applying the Jacobi-Newton algorithm. The resulting schemes have affordable complexity and are inherently robust to NBI. Their accuracy is investigated by means of computer simulations and compared with the relevant Cramer- Rao bound.