Time-domain channel estimation method for MIMO OFDM downlink system

Abstract

The invention relates to a time domain channel estimation method of a multiple-input multiple-output orthogonal frequency-division multiplexing down system. A pilot frequency symbol sequence using orthogonal virtual pilot frequency symbol and code domain is assumed to be used; firstly, a receiving terminal estimates the frequency response of each sub-channel at the actual pilot frequency symbol sub-carrier; then, the channel estimation for the virtual pilot frequency symbol sub-carrier is obtained through the linear interpolation of channel estimation of adjacent symbols used for orthogonal frequency division; the received symbol is re-constructed by utilizing the virtual pilot frequency symbol and the channel estimation thereof, the impulse response estimation of each sub-channel is obtained by ranking the received symbol of the actual pilot frequency symbol sub-carrier in ascending order according to the index value of the sub-carrier and then applying the least square method for time domain regularization, and the channel estimation of all the pilot frequency symbol sub-carriers is obtained after partial Fourier transformation; and finally, the channel frequency response of each user data symbol sub-carrier is obtained through the linear interpolation of channel estimation of the pilot frequency symbol sub-carrier. The invention has the advantages that the channel estimation precision is high, and larger quantity of transmitting antenna can be supported.

Description

technical field [0001] The present invention relates to a time-domain channel estimation method of a Multiple-Input Multiple-Output Orthogonal Frequency Division Multiple Access (MIMO OFDMA) downlink system, in particular to an estimation method based on the partially used subcarrier (PUSC) symbol structure in the IEEE 802.16e standard , belonging to the field of wireless communication systems. Background technique [0002] In recent years, broadband wireless technology has developed rapidly, and WiMAX has gradually become the focus of the wireless communication industry. WiMAX is a broadband wireless access technology based on IEEE 802.16 series standards, and supports four application scenarios: fixed, nomadic, portable and fully mobile. Among them, the mobile broadband wireless access air interface standard 802.16e is regarded by the industry as a next-generation wireless broadband technology that can compete with 3G by virtue of its mobility support, high-speed data ser...

AI Technical Summary

Problems solved by technology

However, since the number of pilot symbols allocated by the IEEE 802.16ePUSC symbol structure is very small, if the frequency-domain least-squares channel estimation method using frequency-domain orthogonal (ie, frequency-division) pilot symbol sequences is used in a MIMO OFDMA system, it will cause Larger estimation error and larger performance loss compared to perfect channel

In related literature, there have been time-domain least squares channel estimation methods using code-domain orthogonal pilot symbol sequences. This method has high estimation accuracy, but requires that the pilot symbol sequence of each transmitting antenna is The time displacement of the pilot symbol sequence is between the channel length and the number of pilots per transmit antenna divided by the number of transmit antennas, so it cannot support more transmit antennas in some channel environments

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