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Blind Channel Estimation in Aperiodic Time-Hopping Ultra-Wideband Communications

机译:非周期性跳时超宽带通信中的盲信道估计

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Impulse radio ultra-wideband (UWB) communication systems employ a time-hopping technique to enable multiple access. Each user is assigned a distinct time-hopping sequence, either periodic or aperiodic, to suppress multiuser interferences. Aperiodic codes have many promising features compared with periodic codes, such as smoothed spectrum and enhanced security. But they pose additional challenges to channel estimation. This paper studies channel estimation issues in aperiodic time-hopping systems. Both a least squares technique and a correlation matching technique are developed. An instantaneous estimate of the mean or correlation of received signals is exploited for simultaneous estimation of all users' channels based on a pulse-rate discrete-time model. If only the desired user's time-hopping codes are available, single-user channel estimators are developed by utilizing the time-varying property of aperiodic time-hopping codes. Performance of each proposed channel estimator is analyzed and numerically evaluated by computer simulations. This paper shows that the correlation matching approach has better performance while the least squares approach has lower complexity. Matched filter receivers based on proposed channel estimators yield detection performance close to corresponding ones with known channel state information. Significant improvement of detection performance is observed by using modified matched filter receivers or multiuser receivers that explicitly take into account interferences to the desired signal.
机译:脉冲无线电超宽带(UWB)通信系统采用时跳技术来实现多路访问。为每个用户分配了不同的时间跳变序列(周期性的或非周期性的)以抑制多用户干扰。与周期性代码相比,非周期性代码具有许多有希望的功能,例如平滑频谱和增强的安全性。但是它们给信道估计带来了额外的挑战。本文研究非周期性跳时系统中的信道估计问题。最小二乘技术和相关匹配技术都得到了发展。对接收信号的均值或相关性的瞬时估计被用于基于脉冲率离散时间模型同时估计所有用户的信道。如果只有所需的用户跳时代码可用,则可以利用非周期性跳时代码的时变特性来开发单用户信道估计器。每个提议的信道估计器的性能都会通过计算机仿真进行分析和数值评估。本文表明,相关匹配方法具有更好的性能,而最小二乘法则具有较低的复杂度。基于建议的信道估计器的匹配滤波器接收器产生的检测性能接近具有已知信道状态信息的相应接收器。通过使用经过修改的匹配滤波器接收器或多用户接收器,可以显着提高检测性能,这些接收器或多用户接收器明确考虑了对所需信号的干扰。

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