Time delay difference compensation method for multi-point cooperation orthogonal frequency division multiplexing (OFDM) system based on subband precoding
A technology of sub-band precoding and cooperative multi-point, applied in the field of time delay difference compensation, can solve the problem of no solution, and achieve the effect of reducing the computational complexity and simplifying the calculation scheme
Inactive Publication Date: 2012-09-19
TSINGHUA UNIV
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[0006] Xidian University's patent "Compensation method for inter-cell delay difference in cooperative multi-point transmission system", Fujitsu's proposal R1-091502 "Pseudo Transmission Timing Control using Cyclic Shift for Downlink CoMP Joint Transmission" and Datang Telecom's proposal R1-090193" Aspects of Joint Processing in Downlink CoMP” both provide solutions to the problem of delay difference between different base stations in coordinated multi-point transmission systems, but the proposed solutions are all aimed at OFDM systems with subcarriers as units, and through the delay difference Compensation makes the transmission delay difference between base stations of each user zero, but for the optimal delay compensation problem in the multi-user OFDM system with subband as the unit, the above patents do not give a corresponding solution
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[0024] The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.
[0025] Taking the coordinated multi-point downlink where two base stations participate in cooperation as an example, the attached figure 1 It represents a multi-point coordinated downlink broadcast system with two base stations and K single-antenna users. The specific implementation steps are as follows:
[0026] Step 1, establish the received signal model
[0027] Assume that each base station has M antennas, and the system adopts N-point FFT OFDM modulation, in which the number of useful subcarriers for transmitting data is G, and every B continuous subcarriers are defined as a subband, and there are a total of L subbands, that is, G =BL. Different subcarriers in each subband adopt a unified precoding vector, that is, for user k, the precoding vectors of subcarriers in subband l are all w kl .
[0028] The received signal of user k on su...
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The invention discloses a time delay difference compensation method for multi-point cooperation orthogonal frequency division multiplexing (OFDM) system based on subband precoding. In the multi-point cooperation OFDM system based on subband precoding, a user feeds estimated channel station information molecular band back to a base station and feeds transmission time delay differences from different base stations to the user at the same time; the base station calculates a time delay compensation value of each user selected by each subband according to the feedback information and then performs phase rotation on data of the user in a frequency domain to finish time delay compensation. A simulation result shows that the obvious system and rate gain can be obtained through the time delay compensation method.
Description
technical field [0001] The invention belongs to the technical field of wireless communication, and in particular relates to a time delay difference compensation method in a multi-point coordinated OFDM system based on sub-band precoding. Background technique [0002] In order to improve the service quality of cell edge users and reduce the interference of adjacent base stations, cooperation between base stations has become one of the key technologies in future mobile communication systems. [0003] Currently, 3GPP defines two coordinated multi-point transmission schemes: Coordinated Beamforming (CB) and Joint Processing (JP). Among them, the user data in the CB scheme is transmitted by a single cooperative base station, and the joint scheduling between the base stations reduces the interference between different cells, which can obtain multiplexing gain; the user data in the JP scheme is jointly transmitted by multiple cooperative base stations, which can obtain diversity ga...
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IPC IPC(8): H04W56/00H04L27/26H04B7/02
Inventor 张秀军赵熠飞周春晖许祥祥周世东
Owner TSINGHUA UNIV