Evaluation of Interpolation Methods for Estimating the Fading Channels in Digital TV Broadcasting
Subject Areas : ICTAli Pouladsadeh 1 , Mohammadali Sebghati 2
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Keywords: Channel Estimation, One-dimensional Interpolation, Fading Channels, DVB-T2 standard,
Abstract :
Variations in telecommunication channels is a challenge of the wireless communication which makes the channel estimation and equalization a noteworthy issue. In OFDM systems, some subcarriers can be considered as pilots for channel estimation. In the pilot-aided channel estimation procedure, interpolation is an essential step to achieve channel response in data subcarriers. Choosing the best interpolation method has been the subject of various researches, because there is no interpolator as the best method in all conditions, and their performance depends on the fading model, signal-to-noise ratio and pilot overhead ratio. In this paper, the effect of different interpolation methods on the quality of DVB-T2 broadcast links is evaluated. A simulation platform is prepared in which different channel models are defined according to the real-world measurements. The interpolation is performed by five widely-used methods (nearest neighbor, linear, cubic, spline, and Makima) for different pilot ratios. After channel equalization by the results of the interpolator, the bit error rate is calculated as the main criterion for evaluation and comparison. The rules of selecting the appropriate interpolator in different conditions is presented. It is generally concluded that for fading scenarios close to flat fading or high pilot overhead ratio, the simple interpolators such as linear interpolator are proper choices. But in harsh conditions, i.e. severe frequency-selective fading channels or low pilot overhead ratio, the more complicated interpolators such as cubic and spline methods yield better results. The amount of improvements and differences are quantified in this study.
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