CN106301688B - Method for supporting inter-cell joint detection in PRACH anti-interference technology - Google Patents

Abstract

A method for supporting inter-cell joint detection in prach anti-interference technology. If local cell A detects interference before adjacent cell B and triggers the prach anti-jamming process, local cell A needs to detect interference from the frequency domain and the PRACH frequency of adjacent cell B. Select an available PRACH location from a frequency domain location other than the domain location; if this cell A detects interference from a neighboring cell B and triggers the prach anti-interference process, this cell A needs to obtain the frequency domain interference and the updated neighboring cell B from the frequency domain. Select an available PRACH location for a frequency domain location other than the PRACH frequency domain location; if two cells detect interference at the same time and trigger the anti-interference process, each will invalidate the current PRACH frequency domain location and notify the other side, one of which will first perform After adjustment, the new PRACH frequency domain location will be notified to the other party, and the other party will select a new PRACH frequency domain location based on the current interference location, effectively solving the problem of overlapping Prach resources in adjacent cells due to the uncontrollable Prach location after the anti-interference function takes effect. It has the characteristics of high efficiency and high accuracy.

Description

A method for supporting inter-cell joint detection in PRACH anti-jamming technology

technical field

The present invention relates to the technical field of PRACH anti-interference, in particular to a method for supporting inter-cell joint detection in the PRACH anti-interference technology.

Background technique

The existing PRACH (Physical Random Access Channel) anti-interference technology is implemented based on the noise floor measurement of a single cell. When continuous time domain or impulse interference for the uplink subframe of the LTE system occurs within the cell coverage, the eNB (evolved Node B , evolved base station) can obtain the noise average value of each prb (PHYSICAL RESOURCE BLOCK: physical resource block) in the frequency domain for a period of time (the timer can be set by itself) through noise floor measurement. When the noise average value of a prb When it is higher than a certain threshold (the noise threshold can be set by yourself), the prb is regarded as the interfered prb, and anti-interference processing will be performed on it. If the prb falls in the resource position reserved by PRACH, The PRACH anti-jamming process will be triggered.

When at least one PRACH is interfered in the resources reserved by PRACH, the PRACH anti-interference process will be initiated. The current PRACH anti-interference processing is based on the PRACH configuration of a single cell. When the PRACH is interfered, the eNB will automatically change the frequency of PRACH. If there is less than 6 prbs in the high frequency area outside the interference area, the PRACH will be reselected from prb 0 to the high frequency direction with the larger prb number. After the PRACH frequency offset adjustment is completed, the RRC (referring to Radio Resource Control) layer will update the system information, and send out paging of SIB update requesting the UE in the cell to update the system information.

Using the current anti-interference solution, the purpose of PRACH anti-interference can be effectively achieved in the scenario of single cell coverage or few cells (PRACH positions can be distinguished from the time domain by manual configuration), but when there are many covered cells, due to When the location in the time domain is limited and the PRACH resource location cannot be completely distinguished in the time domain through manual configuration, if the same interference exists in a large area of the coverage area, the existing implementation scheme will cause a collision of PRACH resources, resulting in PRACH False or missed inspections.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned deficiencies of the prior art, the purpose of the present invention is to propose a method for supporting inter-cell joint detection in the PRACH anti-interference technology, which can effectively solve the problem of PRACH in adjacent cells caused by the uncontrollable PRACH position after the anti-interference function takes effect. The problem of overlapping resources to reduce the occurrence of PRACH false detection and missed detection has the characteristics of high efficiency and high accuracy.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A method for supporting inter-cell joint detection in PRACH anti-interference technology, the steps are as follows:

If this cell A detects interference and triggers the PRACH anti-interference process, the adjacent cell B has not performed anti-interference in the PRACH frequency domain, then this cell A obtains the PRACH frequency domain location of the adjacent cell B, and the PRACH locations of the two cells do not overlap. , the local cell A needs to select an available PRACH position from the frequency domain position of the frequency domain interference and the PRACH frequency domain position of the neighboring cell B;

If this cell A detects interference and triggers the PRACH anti-interference process, the neighboring cell B has completed the PRACH frequency domain anti-interference, and the PRACH frequency domain location of the neighboring cell B has been updated. Select an available PRACH location in a frequency domain location other than the PRACH frequency domain location of the neighboring cell B;

If the local cell A and the neighboring cell B detect interference at the same time and trigger the anti-interference process, each will invalidate the current PRACH frequency domain position, and notify the other cell. Location selection, after the selection, the new PRACH frequency domain location is notified to the opposite cell. When the opposite cell obtains the latest PRACH frequency domain location of the preferentially selected cell, the new PRACH frequency domain location is selected in combination with the current interference location of the cell.

The local cell A calculates the PRACH time-frequency position of the neighboring cell B according to the obtained PRACH configuration index and frequency offset of the neighboring cell B, and the specific method is as follows:

If the physical cell identifier PCI of cell B is less than the PCI of cell A, first calculate the new PRACH frequency domain offset of cell B, the PRACH time domain position of cell B depends on the PRACH configuration index, and confirm cell B by checking the table of the 3GPP protocol. The time domain subframe received by the PRACH; Cell B obtains the current uplink interference situation through the uplink IOT measured by the current B cell, and confirms the PRACH frequency domain of the current B cell by judging the interference noise IOT and the PRACH frequency domain offset currently configured in the B cell Whether the location is available; if available, it is not necessary to adjust the PRACH frequency domain offset of cell B, and the parameter can be notified to cell A; if the interference and the PRACH frequency domain location overlap, that is, the currently configured PRACH frequency domain offset of cell B cannot be used. If it is used, then adjust: select the frequency domain position of 6 consecutive PRB lengths whose IOT is lower than the threshold, as the new PRACH frequency domain position of B cell, notify A cell of the PRACH frequency offset value at this time, A cell According to this, the PRACH frequency domain position to be used is selected, and the PRACH frequency domain offset is obtained according to the PRACH frequency domain position.

Before performing PRACH adjustment in the local cell A, the frequency domain position of the PRACH in the local cell A is set to invalid, which is used to indicate that the local cell A is about to perform PRACH adjustment.

Compared with the prior art, the present invention has the following beneficial effects:

On the basis of the prior art, this invention adds joint detection between neighboring cells during PRACH anti-interference adjustment, and performs PRACH adjustment of the local cell not only according to the interference situation, but also in combination with the PRACH current configuration of the neighboring cell, which effectively avoids the need for When the same interference exists in the area, PRACH resource collision occurs in different cells after PRACH anti-interference adjustment, which leads to the problem of false detection and missed detection of PRACH.

Even if adjacent cells cannot avoid PRACH positions in the time domain, and the same interference exists in a large coverage area, PRACH anti-interference can be effectively implemented to avoid PRACH resource collision after automatic adjustment.

Effectively improve the terminal access success rate of each cell in the interference state, ensure the network access success rate, reduce the false detection probability of PRACH between cells, reduce the interference in the frequency domain where PRACH is located between cells, and ensure the stability of the network.

Description of drawings

FIG. 1 is a flow chart of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings.

Referring to Figure 1, a method for supporting joint detection between cells in a PRACH anti-interference technology, the specific implementation steps are as follows:

Since the start time and length of the noise floor detection timer between cells may be different, when there is interference in the coverage area, different cells may start PRACH anti-interference at different times.

When the interference position of cell A is [X, Y], the PRACH frequency domain position of cell A is [M, N], and the interference position includes the PRACH frequency domain position, then cell A needs to adjust the frequency domain position of PRACH. Neighboring cell B has not yet detected interference, and neighboring cell B has not yet performed anti-interference in the PRACH frequency domain, so the PRACH of neighboring cell B has interference at this time, so this cell A has obtained the PRACH frequency domain location of neighboring cell B at this time. [P, Q], and the PRACH positions of the two cells do not overlap, at this time, cell A needs to interfere in the frequency domain [X, Y] and the adjacent cell B's PRACH frequency domain position [P, Q] other than the frequency domain position [P, Q] Find new PRACH locations available for A cell.

When the interference position of cell A is [X, Y], the PRACH frequency domain position of cell A is [M, N], and the interference position includes the PRACH frequency domain position, then cell A needs to adjust the frequency domain position of PRACH. Neighboring cell B has completed the PRACH frequency offset adjustment at this time, that is, cell B has completed the anti-interference in the PRACH frequency domain, and the PRACH frequency domain position [P, Q] of the original neighboring cell B is updated to [U, V]. The PRACH of B is outside the interference area. At this time, cell A obtains the latest PRACH frequency domain position [U, V] of neighboring cell B. In order to ensure that the PRACH positions of the two cells do not overlap, cell A needs to Frequency domain interference [X, Y] and the frequency domain location outside the PRACH frequency domain location [[U, V] of neighboring cell B to find a new PRACH location available for cell A.

When the interference location of cell A is [X, Y], the PRACH frequency domain location of cell A is [M, N], and the interference location includes the PRACH frequency domain location, then cell A needs to adjust the PRACH frequency domain location. The interference position [S, T] of the neighboring cell B, the PRACH frequency domain position [P, Q] of the neighboring cell B, and the interference position includes the PRACH frequency domain position. At this time, the neighboring cell B needs to adjust the PRACH frequency domain position.

When two cells perform PRACH anti-interference at the same time, each of them sets the current PRACH frequency domain position invalid, and notifies the other cell. Domain location selection. Since the obtained configuration of the other party is an invalid value, it indicates that the other party is about to adjust, so the party who adjusts first does not need to consider the configuration of the other party at this time, and can only adjust according to the interference situation.

Since it is feasible for either side of the two cells to adjust first, and the PCI of adjacent cells will be avoided as much as possible during network planning, the one with the larger PCI of the two cells is selected to be adjusted first, and the one with the smaller PCI will wait for the other side to complete the adjustment. Then trigger the process again. At this time, since the PCI of cell B is smaller than the PCI of cell A, the new PRACH frequency domain offset of cell B is calculated first. The PRACH time domain position of cell B depends on the PRACH configuration index. By checking the 3GPP protocol table, it can be confirmed that B The time domain subframe of the PRACH reception of the cell; the B cell can obtain the current uplink interference through the uplink IOT measured by the current B cell, and confirm the current PRACH frequency of the B cell by judging the IOT and the PRACH frequency offset currently configured in the B cell. If the domain location and interference overlap, that is, the PRACH frequency domain offset of the currently configured B cell is not available, then adjust: select the frequency domain location of 6 consecutive PRB lengths whose IOT is lower than the threshold as the new PRACH frequency domain of the B cell. If the location is determined, notify cell A of the new PRACH frequency domain location [E, F] at this time. After cell A obtains the latest PRACH frequency domain location of cell B, it selects a new PRACH frequency domain based on the current interference location of cell A. Location.

The LTE frequency domain bandwidth is divided according to the subcarrier bandwidth, and then a PRB is located according to every 12 consecutive subcarriers and 7 time domain symbols in the frequency domain. In this way, the 20MHz frequency domain bandwidth is defined as 100 effective PRBs, and the PRBs are numbered from the low frequency and are 0. -99.

The PRACH receiving position is: starting from 0, 6 consecutive PRBs starting from the PRB after the PRACH frequency domain offset. For example, the frequency domain offset value is 15, starting from 0PRB to 14PRB (that is, 15 starting from 1) is the offset range, and the PRB starting from 15PRB is the PRB starting from the PRACH frequency domain position.

In this scenario, the PRACH configuration is set to an invalid value to prevent both cells from simultaneously acquiring the value before each other's adjustment, resulting in the situation that both parties adjust to the same position.

Claims (3)

1. A method for supporting inter-cell joint detection in PRACH anti-interference technology is characterized by comprising the following steps:

if the adjacent cell B does not perform anti-interference of a PRACH frequency domain when the cell A detects interference and triggers a PRACH anti-interference flow of a physical random access channel, the cell A acquires the PRACH frequency domain position of the adjacent cell B, the PRACH positions of the two cells are not overlapped, and the cell A needs to select an available PRACH position from the frequency domain interference and the frequency domain position except the PRACH frequency domain position of the adjacent cell B;

if the neighboring cell B finishes the anti-interference of the PRACH frequency domain when the cell A detects the interference and triggers the PRACH anti-interference process, and the PRACH frequency domain position of the neighboring cell B is updated, the cell A needs to select an available PRACH position from the frequency domain interference and the frequency domain position outside the PRACH frequency domain position of the updated neighboring cell B;

if the cell A and the adjacent cell B simultaneously detect interference and trigger an anti-interference process, respectively setting the frequency domain position of the current PRACH as invalid and informing the opposite cell, selecting the larger PCI one of the two cells to preferentially select the frequency domain position, informing the new PRACH frequency domain position to the opposite cell after selection, and after the opposite cell obtains the latest PRACH frequency domain position of the preferentially selected cell, selecting the new PRACH frequency domain position by combining the interference position of the current cell.

2. The method for supporting inter-cell joint detection in the PRACH anti-interference technology according to claim 1, wherein the cell a calculates the PRACH time-frequency position of the neighboring cell B according to the acquired PRACH configuration index and frequency offset of the neighboring cell B, and the specific method is as follows:

if the physical cell identification PCI of the cell B is smaller than the PCI of the cell A, calculating a new PRACH frequency domain offset of the cell B, wherein the PRACH time domain position of the cell B depends on a PRACH configuration index, the cell B obtains the current uplink interference condition through the uplink IOT measured by the current cell B, and whether the PRACH frequency domain position of the current cell B is available is determined by judging the interference noise IOT and the PRACH frequency domain offset currently configured by the cell B; if the time domain position is available, the PRACH frequency domain offset of the cell B is not required to be adjusted, and the time domain position is informed to the cell A; if the interference and the PRACH frequency domain position are overlapped, namely the PRACH frequency domain offset of the currently configured B cell is unavailable, adjusting: selecting the frequency domain position of 6 continuous physical resource blocks PRB length with IOT lower than threshold as the new PRACH frequency domain position of the cell B, informing the PRACH frequency domain deviation value of the time to the cell A, selecting the PRACH frequency domain position used by the cell A according to the PRACH frequency domain position, and obtaining the PRACH frequency domain deviation according to the PRACH frequency domain position.

3. The method of claim 1, wherein the frequency domain position of the PRACH of the cell a is set to be invalid before the PRACH adjustment is performed in the cell a, and the method is used to mark that the PRACH adjustment is to be performed in the cell a.

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