Method for compensating delay difference among cells in cooperative multi-point transmission system

Abstract

The invention discloses a method for compensating delay difference among cells in a cooperative multi-point transmission system, mainly solving the problems that the traditional method can not naturally combine signals at air interfaces and not fully develop the potential of CoMP. The realization process comprises the following steps: (1) a user calculates out the delay difference among the cellsand delayed sampling points according to CSI-RS; (2) the user calculates out a phase rotation factor according to the delayed sampling points, and the phase rotation factor is fed back to a serving cell which shares the phase rotation factor with a cooperative cell; (3) the cooperative cell compensates the phase rotation of a signal according to the phase rotation factor; (4) the user calculates out the carrier phase deviation factor of the cooperative cell according to the delay difference, and the phase deviation factor is fed back to the serving cell which shares the phase deviation factorwith the cooperative cell; and (5) the cooperative cell compensates the phase deviation of the signal according to the phase deviation factor. The method can naturally combine signals received by theuser at the air interfaces, thereby obtaining extra array gain.

Description

technical field [0001] The invention belongs to the technical field of communication, and in particular relates to a compensation method for different delays of arriving users due to different cells, and is applied in a coordinated multi-point transmission CoMP system. Background technique [0002] Long Term Evolution (LTE) is the largest new technology research and development project launched by 3GPP in the past two years to meet future communication needs, and is regarded as the mainstream technology for the evolution from 3G to 4G. At the 3GPP RAN1#53 meeting, Ericsson summarized the concepts of "Multi-cell MIMO" and "Network MIMO" proposed by many companies before, and proposed the term "CoMP" to express a large number of multi-cell collaborations with the same essence Program. Coordinated multi-point transmission can effectively reduce inter-cell interference and improve user performance at the cell edge. [0003] Currently, 3GPP defines two joint multipoint transmis...

AI Technical Summary

Problems solved by technology

For the joint processing scheme, because the data comes from multiple cells, it can obtain diversity gain and improve the performance of the edge cell. However, due to the different distances from different cells to the user, the arrival time will be out of sync, resulting in a delay difference between cells.

[0004] In the proposal R1-091502 "Pseudo Transmission Timing Control using Cyclic Shift for Downlink CoMP Joint Transmission", Fujitsu proposed to use cyclic shift to perform pseudo-time control in downlink CoMP JP transmission to solve the problem of different delays due to different cells reaching users, but this This method cannot make the signals of different cells combine naturally at the air interface, which will degrade the system performance

In addition, the coherent joint transmission proposed by Datang Telecom in the proposal R1-090193 "Aspects of Joint Processing in Downlink CoMP" is to multiply the data streams of each cell by different phase factors so that the signals of different cells are naturally combined at the air interface. , on the basis of obtaining precoding gain, power gain and diversity gain, additional transmission array gain is obtained, but this method has a great impact on the time delay difference between different cells arriving at users, and causes system failure when the time delay is large. performance drops dramatically

Images