TW201532453A - Method and user equipment for triggering network assisted interference cancellation and suppression - Google Patents

Abstract

The present invention relates to a method for a user equipment to trigger network assisted interference cancellation and suppression, comprising: testing for interference generated by neighboring cells; identifying, on the basis of results of said testing, neighboring cells causing interference; and reporting to the base station of the cell in which the user equipment is located information about the identified neighboring cells causing interference, said reporting being used to provide said base station assistance information for cancelling and suppressing interference and to enable the target receiving said assistance information to make a determination. The present invention also relates to a user equipment that implements said method.

Description

Method and user equipment for triggering network assisted interference cancellation and suppression

The present invention relates to communication technologies, and in particular, to a method and user equipment (UE) for triggering Network Assisted Interference Cancellation and Suppression (NAICS).

The current requirements for mobile networks to support data applications with high throughput and spectral efficiency have driven the development of Orthogonal Frequency Division Multiplexing (OFDM) 4G networks including WiMAX, 3GPP LTE and The needs of LTE-A. Both LTE and LTE-A are interference limited systems located in areas with dense cells. Therefore, an important research project for LTE and LTE-A systems is inter-cell interference coordination. In the discussion of Release-8/9, inter-cell interference coordination (ICIC) between macro cells based on RNTP/HII/OI is proposed. In the discussion of Release-10, CoMP and almost blank subframes are proposed for interference coordination between macro cells and micro cells. In Release-11, FeICIC interference suppression and cancellation with network-assisted CRS is proposed for One step performance improvement.

In order to cope with exponentially growing data services, dense cell placement and improved cell spectral efficiency are required. Co-channel interference (whether caused by inter-cell interference or by users in a co-scheduled cell) is a major limiting factor in achieving better network capabilities. Interference suppression or cancellation on the receiving side can also provide significant performance gains compared to coordination on the transmission side. Therefore, NAICS for LTE has been confirmed as a research project for Release-12.

The FeICIC interference suppression and cancellation mechanism with network-assisted CRS in Release-11 is mainly triggered by the network side, and only a small amount of network information is involved in the process of interference cancellation. However, the NAIC performs interference cancellation for the physical downlink shared channel (PDSCH), and thus involves a large amount of network information. In this case, if the existing interference cancellation trigger mechanism is adopted, the auxiliary information for eliminating neighboring cells will be sent to all UEs without distinction, and each UE is required to have a large amount of storage space for storing these. A large amount of network information, but also has complex computing power for repeated iterative calculations. In addition, for each UE, the interference cancellation operation is not required at any time, and it needs to be eliminated only when the interference reaches a certain positioning time. Therefore, there is a need to provide a NAICS triggering mechanism that does not require significant changes in the processing capabilities of the UE and is more targeted for each UE.

In order to overcome the above problem, an embodiment of the present invention provides a method for triggering network-assisted interference cancellation and suppression by a user equipment, including: detecting interference generated by a neighboring cell; and causing the interference-causing phase according to the result of the detection. The neighboring cell performs screening; and reports, to the base station of the local cell where the user equipment is located, the filtered information of the neighboring cell that causes interference, and is used for assisting the base station of the local cell to eliminate and suppress interference. The content of the information and the object receiving the auxiliary information are determined.

Specifically, the detecting the interference generated by the neighboring cell includes detecting, by a reference signal of the local cell, a power of a reference signal of the neighboring cell, and obtaining a ratio of the two; and/or detecting the user equipment. The data transmission quality in the present cell.

Specifically, the reference signal of the local cell and the reference signal of the neighboring cell include at least a common reference signal, a demodulation reference signal, or a channel state information reference signal.

Specifically, when the reference signal of the local cell and the neighboring cell is a demodulation reference signal, the demodulation reference signal includes at least a scrambling identifier, and is used to obtain a demodulation reference signal sequence, thereby obtaining the The power level of the reference signal.

Specifically, performing screening on the adjacent cell that causes interference according to the result of the detecting includes: using, by using, the adjacent cell that meets a ratio of the reference signal of the local cell to a reference signal of a neighboring cell in a predetermined interval The neighboring cells are filtered.

In particular, the criterion for screening the neighboring cell causing the interference is preset in the user equipment, or is the base station of the local cell. Configured.

Specifically, the detecting the data transmission quality of the user equipment in the local cell includes at least detecting a channel quality indication or a hybrid automatic repeat request.

In particular, the method further includes screening the interfered physical resource block pair according to the detection result of the data transmission quality, and the neighboring cell that interferes with the filtered physical resource block pair The information is reported to the base station of the community.

Another embodiment of the present invention provides a user equipment implementing any of the methods described above.

The method and user equipment for triggering NAICS provided in the embodiment of the present invention fills in the blank of the 3GPP LTE technology related to the NAICS trigger mechanism, and provides a low-cost mechanism for the UE to trigger the NAICS. This mechanism is not only more targeted for the UE, but also considers the interference factors in the data while considering the power interference, so that the interference cancellation can be more accurately distinguished, and the interference cancellation is improved. effectiveness.

500‧‧‧User equipment

502‧‧‧ receiving module

504‧‧‧Transmission module

506‧‧‧Monitoring module

FIG. 1 is a flowchart of a method for triggering NAICS by a UE according to an embodiment of the present invention; FIG. 2 is a schematic diagram of DM-RS partial configuration information for an X2 interface according to an embodiment of the present invention; Shown by the UE according to an embodiment of the present invention A schematic diagram of a portion of the message content of the reporting by the base station; FIG. 4 is a schematic diagram showing part of the message content reported by the UE according to an embodiment of the present invention; and FIG. 5 is a flowchart showing execution triggering according to an embodiment of the present invention. Schematic diagram of the structure of the UE.

The making and using of the embodiments of the present invention are discussed in detail below. However, it should be understood that the present invention provides many possible and innovative concepts that can be implemented in various specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the invention and are not intended to limit the scope of the invention.

1 is a flow chart of a method for triggering NAICS by a UE according to an embodiment of the present invention. At step 102, the UE detects interference generated by neighboring cells. The detection of interference generated by neighboring cells may include multiple aspects. According to an embodiment, the detecting may include detecting a reference signal of a local cell where the UE is located and a power of a reference signal of a neighboring cell, and obtaining a ratio of the two.

According to an embodiment, the reference signal of the current cell and the neighboring cell may be a cell-specific reference signal (CRS). In the LTE system using the CRS, the UE can detect the reference signal received power (RSRP) of the CRS reference signal of the local cell and the neighboring cell, and obtain the ratio of the two. The LTE-A system no longer uses the CRS signal, so it can also use the demodulation reference signal (demodulation reference signal). DM-RS) or channel state information reference signal (CSI-RS) is used to detect interference of neighboring cells.

According to one embodiment, in a system employing DM-RS, DM-RS signals of different cells will share the same resource location. Since different DM-RS signals are transmitted with the PDSCH packet, if the called resource is reused by the neighboring cell, if the UE can obtain the DM-RS signal sequence of the neighboring cell, the neighboring cell pair can be known. Interference generated by PDSCH.

Further explanation can be made through the following examples. It is assumed that there is one serving cell A and two cells B and C adjacent to A in the system. The signal received by the UE in A is Y, the DM-RS sequences of the three cells are S _A , S _B and S _C respectively, and the power constant matrices for precoding the corresponding base stations are X _A , X respectively. _B and X _C , and the wireless channels experienced by precoding are H _A , H _B and H _C . Then Y can be expressed by the following formula (1):

Since the precoding operation does not change the power level of the transmitted signal, the equivalent channel It can also represent the transmit power level after channel path loss. That is, if the UE can learn the S _A , S _B and S _C sequences, it can be obtained. , , Average power.

According to the existing DM-RS sequence generation mechanism, the initialization of the sequence is indicated by the scrambling identifier to indicate the n _SCID and the scrambling identifier. The effect of n _SCID is "0" or "1", and Then an integer between {0,...,503}. Therefore, as long as the UE knows the two parameters of the DM-RS signal transmitted by the neighboring cell, the power level of the DM-RS signal can be known. Therefore, whether it is to trigger NAICS or to achieve interference cancellation of PDSCH to PDSCH, the UE needs to know the configuration information of the DM-RS signal of the neighboring cell. Therefore, it is necessary to make certain adjustments to the existing DM-RS configuration.

Figure 2 shows a schematic diagram of the DM-RS part configuration information for the X2 interface. Of course, the configuration information of the DM-RS can also adopt many other methods as long as the scrambling identifiers for the DM-RS signals of the respective neighboring cells can be known to each other.

According to another embodiment of the application, the detecting of the interference of the neighboring cell may further comprise detecting the data transmission quality of the UE. The reason for this operation is that in the existing radio resource management/radio resource management (RRM/radio link management, RLM for short) detection, although the power of the neighboring cell may be higher than the power of the local cell. It is much higher, but if the traffic of the neighboring cell is very limited, it will not cause serious interference to the UE of the cell. In this case, the same channel interference does not cause a large performance loss. For this reason, the channel quality indicator (CRI) and the hybrid automatic repeat request (HARQ) can be detected to obtain the data transmission quality of the UE.

In step 104, the UE may perform screening on neighboring cells according to the detection result of step 102. Because it does not need to interfere with all detected The neighboring cells are all performing interference cancellation processing. Only interference generated by neighboring cells whose detection result exceeds a predetermined index needs to be eliminated. The predetermined indicator may be preset in the production process of the UE, or may be configured by the base station, and transmitted to the UE through, for example, system broadcast information (SIB-x) or UE-specific RRC signaling.

According to an embodiment, the range of the predetermined indicator for the power ratio may be [-9 dB, +9 dB], that is, the reference signal power of the local cell and the reference signal power ratio of the neighboring cell may fall within the range of the adjacent cell. Used as a filtered neighboring cell that produces interference. Of course, this range is just an example, and different indicators can be set according to different application situations.

According to another embodiment, the UE may also filter out a physical resource block (PRB) that is severely interfered based on the detected CQI, HARQ, and the like according to a predetermined indicator.

In step 106, the UE reports the filtered information of the neighboring cell causing the interference to the base station of the local cell. FIG. 3 is a schematic diagram showing the content of a message part of a neighboring cell that the UE reports to the base station of the local cell, and the report can be transmitted by using any form of message. According to one embodiment, the identified neighboring cells may be ranked in the report in descending order of power.

According to another embodiment, for the data transmission quality situation, the UE may report the filtered information of the severely interfered PRB pair to the base station of the local cell, and the information of the neighboring cell that interferes with the PRB pair. Figure 4 shows that the UE reports to the base station of the cell that it has been filtered. A schematic diagram of a portion of a message of a heavily interfered PRB pair, including the identity of the PRB pair and the identity of the neighboring cell to which the interference occurs. This report can be transmitted in any form of message. In addition, the PRB group can also be used as a unit to report interference, and the PRB group can include a predetermined number of PRB pairs.

According to the information reported by the UE, the base station of the local cell sends targeted auxiliary information to different UEs according to the received screening result, which is used to eliminate and suppress the influence of neighboring cells that cause interference to the specific UE. .

The method described in the present invention can be applied to a serving cell or a UE in another cell.

According to an embodiment, the UE may decide whether to report to the base station to trigger the NAICS according to the detection result described above. If the interference caused by the neighboring cell is lower than the predetermined level, both in terms of reference signal power and data transmission, the UE may choose not to report to the base station of the cell.

FIG. 5 is a schematic structural diagram of a UE for performing the foregoing method according to an embodiment of the present invention. The user equipment 500 includes a receiving module 502 and a transmitting module 504 for performing receiving and transmitting operations in the above method, and a monitoring module 506 for performing operations such as detection and determination and control in the above method.

It will be readily apparent to those skilled in the art that materials and methods can be varied within the scope of the invention. It should also be understood that the present invention provides many applicable innovative aspects in addition to the specific context for illustrating the embodiments. Read. Accordingly, the scope of the patent application is intended to cover such processes, machines, manufactures, compositions, compositions, methods, or steps.

Claims (9)

A method for triggering network-assisted interference cancellation and suppression by a user equipment, comprising: detecting interference generated by a neighboring cell; screening the neighboring cell that causes interference according to the detection result; and the local cell to which the user equipment is located The base station reports the filtered information of the neighboring cell causing the interference, and is used for determining, by the base station of the local area, the content of the auxiliary information for canceling and suppressing interference and the object receiving the auxiliary information. The method of claim 1, wherein the detecting the interference generated by the neighboring cell comprises detecting the power of the reference signal of the local cell and the reference signal of the neighboring cell, and obtaining a ratio of the two; and/or Detecting the data transmission quality of the user equipment in the local cell. The method of claim 2, wherein the reference signal of the local cell and the reference signal of the neighboring cell at least comprise a common reference signal, a demodulation reference signal or a channel state information reference signal. The method of claim 3, wherein when the reference signal of the local cell and the neighboring cell is a demodulation reference signal, the demodulation reference signal includes at least a scrambling identifier for obtaining a demodulation reference signal sequence. Thereby obtaining the power level of the reference signal. The method of claim 2, wherein screening the neighboring cell causing interference according to the result of the detecting comprises: meeting the The neighboring cell with a ratio of the reference signal of the cell to the reference signal power of the neighboring cell in a predetermined interval is used as the neighboring cell that is filtered. The method of claim 2, wherein the criterion for screening the neighboring cell causing the interference is preset in the user equipment or configured by the base station of the local cell. The method of claim 2, wherein the detecting the data transmission quality of the user equipment in the local cell comprises at least detecting a channel quality indication or a hybrid automatic repeat request. The method of claim 7, further comprising screening the interfered physical resource block pair according to the detection result of the data transmission quality, and the neighboring cell that interferes with the filtered physical resource block pair The information is reported to the base station of the community. A user equipment that triggers network-assisted interference cancellation and suppression according to the method of any one of claims 1 to 8.