Interference cancellation interleaving OFDMA uplink CFO estimation method

Abstract

The invention relates to an interleaved OFDMA uplink carrier frequency deviation CFO estimation method for iterative multi-user interference cancellation. The CFO of the OFDMA can damage the orthogonality between subcarriers, serious inter-carrier interference ICI is generated, and multiple access interference MAI can also be brought. In the scheme of the invention, the method comprises the following steps: the base station sorts the users according to the received signal intensities; the base station estimates from the user with the strongest receiving power to the user with the lowest power; feedback signals of the estimated users with the higher receiving power and feedback signals of the weak users estimated in the last iteration are all subtracted from the receiving signals, interference of frequency deviation of other users on pilot frequency point signals of the users is eliminated and then multiplied by a phase compensation factor, and the CFO of the current user is obtained by maximizing the power of the pilot frequency point. And the next iteration is entered until the CFO of the user with the weakest receiving power is estimated. The estimation method has the advantages that the estimation precision is high, the convergence speed is high, a small number of pilots are inserted into data sent by a user, and a large number of frequency bands do not need to be occupied.

Description

technical field [0001] The present invention relates to the field of communication technology, and more specifically, relates to an interleaved OFDMA uplink carrier frequency offset CFO estimation method based on iterative multi-user interference elimination and pilot assistance. Background technique [0002] OFDMA (Orthogonal Frequency Division Multiple Access) is an efficient wireless communication system multiple access scheme based on OFDM, which realizes multiple users communicating with the base station at the same time by dividing disjoint subcarriers for users. Although OFDMA inherits the advantages of OFDM against intersymbol interference (ISI) caused by multipath fading channels, high spectrum efficiency, and easy implementation using FFT / IFFT, it also inherits OFDM's high sensitivity to carrier frequency offset (CFO). Disadvantages, especially in the OFDMA uplink, different users arrive at the receiving end through different channels, and the CFO of all users is d...

AI Technical Summary

Problems solved by technology

These methods not only reduce the efficiency of spectrum utilization, but also when the total number of subcarriers in the system is constant, as the number of users increases, the pilot spacing and the number of pilots for each user are mutually constrained, and the reduction of pilot spacing will increase the inter-pilot interference. , the reduction in the number of pilots used by each user will be affected by deep channel fading, both of which will degrade the estimation performance

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