A Wideband Precoding and Interference Suppression Method Considering User Delay Differences in a Two-User Distributed Cooperative Transmission System
A distributed collaboration and transmission system technology, applied in the field of wireless communication transmission, can solve problems such as large errors and inability to be solved by sending in advance, and achieve the effect of reducing complexity and performance
Active Publication Date: 2020-05-19
SOUTHEAST UNIV
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Problems solved by technology
However, for distributed multi-user MIMO-OFDM, since multiple nodes will "take care of one thing and lose another" for multiple users, it cannot be solved by sending in advance
Therefore, the traditional precoding design and interference suppression based on the coherent bandwidth will bring large errors
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[0057] Such as figure 1 and Figure 4 As shown, a wideband precoding and interference suppression method considering user delay difference in a two-user distributed cooperative transmission system includes the following steps:
[0058] (1) For the uplink, the access point performs time-frequency synchronization with the first arriving user respectively according to the uplink synchronization signal, and estimates the relative time delay difference of another user arriving later with respect to the user arriving earlier; Suppose there are two access points, user 1 is the closest to access point 1, and user 2 is the closest to access point 2. The cyclic prefix sampling deviation caused by delay difference between user 1 and access point 2 is τ 1 samples, the sampling deviation from user 2 to access point 1 is τ 2 samples;
[0059] (2) For the downlink, the base station calculates the relative delay difference between the access point and the user according to the uplink time-...
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The invention discloses a broadband pre-encoding and interference suppressing method considering user delay difference in a two-user distributed cooperative transmission system. The method includes the following steps: each access point synchronizes the time and frequency with a user arriving first according to a synchronization signal of an uplink, and estimates the relative delay difference of the other user arriving later relative to the user arriving first; the delay difference between a downlink access point and the users is calculated according to the time and frequency synchronization of the uplink; channel matrixes of the uplink and the downlink are obtained according to the result of channel estimation, and a downlink multi-user pre-encoding matrix is calculated; and a pre-codingmatrix and an interference suppressing matrix of a kth sub carrier are calculated according to the sampling deviation. According to the method of the invention, the pre-coding or interference suppressing matrix is calculated only once in the coherent bandwidth, and the matrixes of the other sub carriers can be generated by rotating the matrix. Therefore, channel change caused by sampling deviationis compensated, and the multi-user pre-encoding and interference suppressing complexity and performance of the transmission system are reduced.
Description
technical field [0001] The invention relates to the technical field of wireless communication transmission, in particular to a broadband precoding and interference suppression method considering user delay difference in a two-user distributed cooperative transmission system. Background technique [0002] Distributed multi-antenna cooperative transmission is a key technology of 4G and 5G. Combining distributed multi-antenna with OFDM can convert frequency-selective channels into flat MIMO channels on each subcarrier, so OFDM-based distributed MIMO cooperative transmission is adopted by 4G and 5G. However, with the increase of the number of base stations and users participating in the cooperation, the complexity of calculating precoding or joint detection for each subcarrier will be very large. When a point-to-point MIMO-OFDM system is implemented, it is usually assumed that channels are correlated within a coherent bandwidth, thereby reducing the number of precoding calculat...
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IPC IPC(8): H04B7/0413H04B7/0456H04L25/03
Inventor 王东明狄晓伟吕志伟王佳才尤肖虎
Owner SOUTHEAST UNIV