Optimization For Channel Estimation Of Wireless Communitcations With Short Packets In URLLC

With the progress and development of technology,the delay expected to achieve in the fifth-generation wireless communication scenario is much lower than that the current wireless system can meet.The main challenge in solving these problems is to develop short packet transmission,however most wireless standards currently use long packet transmission.Compared to the long packet communication,the short packet structure is very different,and the resources that can be used to estimate the channel are limited by the packet size,too small will cause an inaccurate estimation,while too big will occupy the period of transmitting effective data.So it is crucial to find a effective method to estimate the channel and interference covariance in the short packet communication scenario.Accurate and reliable estimation should be given without wasting useful signal resourcesBased on the common IT of Things system,I first compares two common pilot-based channel estimation algorithms,namely LS and MMSE estimation algorithms,and then propose an efficient channel estimation technology combining pilot and data symbols,using useful information during data transmission to improve the reliability of short packet transmission.Different from the previous method that specifically use pilot and interference sequences to estimate the channel,in this method,the receiver filter calculates MSE of the channel using different data symbols as virtual pilot,then the minimum MSE symbols are selected to combine with the pilot for channel estimation.Simulation results show that the algorithm does improve the channel estimation quality and data symbol selection is very important for its reliability.The most reliable data symbols and random selected data symbols have a great influence on the accuracy of channel estimation.Moreover,this paper analyzes the performance of traditional MMSE receiver and finds that the signal-to-noise ratio received by the traditional MMSE is bad for short packet transmission,thus it is not suitable for short packet transmission.Therefore,a method to estimate the interference covariance matrix with the data symbols instead of interference sequences is proposed.The simulation results do improve the performance of the receiver.The proposed channel estimation method based on joint pilot and data symbol is applied to this receiver,at the same time,convolution coding and soft judgment Viterbi decoding are adopted to further improve the performance of the receiver.The simulation results show that the receiver greatly improves the reliability of the transmission without wasting packet resources.