Preamble design-based cooperative diversity orthogonal frequency division multiplexing (OFDM) timing and frequency offset estimation method

Abstract

The invention discloses a preamble design-based cooperative diversity orthogonal frequency division multiplexing (OFDM) timing and frequency offset estimation method in the field of wireless communication, which aims to mainly solve the problems of low accuracy, high complexity and low transmission efficiency of timing and frequency offset estimation from relays to a destination in a conventional cooperative diversity OFDM system. The method is implemented by the following steps of: (1) designing training sequences of each relay; (2) simultaneously transmitting the training sequences to the destination by using each relay; (3) estimating rough timing offset between the relays and the destination; (4) estimating fine timing offset between each relay and the destination; (5) calculating estimation values of the timing offset between each relay and the destination; (6) estimating decimal frequency offset between each relay and the destination; (7) estimating integral frequency offset between each relay and the destination; and (8) calculating the estimation values of the frequency offset between each relay and the destination. By the method, the timing and frequency offset estimation performance can be improved, the operational complexity can be reduced and the transmission efficiency can be improved.

Description

technical field [0001] The invention belongs to the technical field of communication, and relates to a method for estimating timing and frequency offset in a wireless communication system, in particular to a method for estimating timing and frequency offset from a relay to a destination in a cooperative diversity OFDM system, which is used for the destination Demodulates the received signal. Background technique [0002] In wireless communication networks, diversity in time, frequency and space can reduce the impact of channel fading on received signals. Cooperative diversity technology enables each single-antenna user in the network to share each other's antennas to form a virtual multi-antenna array to achieve transmission or Receive diversity is a virtual multiple-input multiple-output MIMO technology, which was originally proposed by Laneman and Womell. Orthogonal frequency division multiplexing OFDM technology can resist the frequency selective fading of wireless channe...

AI Technical Summary

Problems solved by technology

However, the OFDM system is very sensitive to synchronization errors such as timing offset and frequency offset, and non-ideal synchronization will seriously affect the performance of the OFDM system, so synchronization technology is one of the key technologies in the cooperative diversity OFDM system

[0003] In response to this problem, some researchers have proposed the use of anti-delay transmission technology to avoid timing offset estimation. Although these methods are very novel, they impose many conditions on data transmission and cooperation between users, thus limiting its application

In 2008, Andreas Ibing published "MMSE channel estimation and time synchronization tracking for cooperative MIMO-OFDM with propagation delay differences" in "5th IEEE International Symposium on Wireless Communication Systems" (5th IEEE International Symposium on Wireless Communication Systems) (2008) ("MMSE Channel Estimation and Timing Synchronization Tracking in Cooperative Diversity MIMO-OFDM System with Transmission Delay Difference Environment") considered timing offset estimation, but did not involve frequency offset estimation; in 2009, Yusi Cheng et al. in "Proceedings of the2009 IEEE 70th Vehicular Technology Conference" (the 70th IEEE VTC International Conference) (2009) published "Preamble design and synchronization algorithm for cooperative relay systems." ("Research on training sequence design and synchronization algorithm in cooperative diversity systems" ) considers timing and frequency offset estimation at the same time, but its timing and frequency offset estimation accuracy is not high, and because its training sequence length is close to three OFDM symbols, the transmission efficiency is low, and in timing offset estimation, especially coarse timing In offset estimation, each relay needs to do sliding correlation at different intervals, which has high complexity

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