A Time-Domain Pilot Design For Co-Channel Interference Suppression In Channel Estimation Of OFDM Systems

Orthogonal frequency division multiplexing (OFDM) technology has become the core technology in the next generation communication. As the spectral efficiency increases, the co-channel interference (CCI) gradually replaces the Gaussian noise and becomes one of the most important factors which affect the communication. CCI has the impact on channel estimation in OFDM systems, and the performance of the channel estimation directly relates to the quality of the demodulation at the receiver.This paper proposes a novel time-domain pilot design in OFDM systems, and then develops some algorithms of channel estimation for CCI suppression based on these pilots. This paper firstly analyzes simple and orthogonal time-domain pilots, the word "simple" means the time-domain pilots only capture a sample point in time-domain, and the word "orthogonal" means the time-domain pilots satisfy some orthogonal rules. Theoretical analysis indicates that these time-domain pilots not only improve the performance of the channel estimation, but also reduces the complexity. However, the time-domain pilots increase the peak to average power ratio (PAPR) of the OFDM signal, and the number of CCI transmitters which can be distinguished at the receiver decreases as the maximum channel delay increases. To solve these two problems, this paper designs the optimal pilot length and the optimal pilot sequence to reduce the PAPR through utilizing the minimize-maximum rule, then eliminates the last channel paths which contain relatively small channel power to increase the number of CCI transmitters which can be distinguished at the receiver. Simulation results verify the theoretical analysis of the simple and orthogonal time-domain pilots, and show that the improved time-domain pilots can also achieve better performance compared with some conventional algorithms.