CN104469804A - Blind detection method of physical downlink control channel - Google Patents

Abstract

The present application discloses a method for blind detection of a physical downlink control channel, which uses the detection status of the PDCCH format and DCI information used by the UE to detect the DCI last time to adjust the detection priority of each PDCCH format in the PDCCH format candidate set, so that In the current blind detection, the UE can quickly use the correct PDCCH format to detect DCI information, thereby reducing the number of PDCCH format attempts during blind detection, improving blind detection efficiency, and reducing UE power consumption.

Description

Blind detection method of physical downlink control channel

technical field

The invention relates to mobile communication technology, in particular to a blind detection method of a physical downlink control channel (PDCCH).

Background technique

In the LTE system, uplink and downlink resource scheduling is performed through a physical downlink control channel. For downlink resource allocation, the eNodeB first transmits resource allocation related information to the UE through the physical downlink control channel (PDCCH). After the UE detects the PDCCH sent to itself, it detects the data channel according to the control information in the PDCCH. Shared channel (PDSCH). For uplink, when the UE needs to send uplink data, it needs to initiate a scheduling request to the eNodeB, and the eNodeB indicates the uplink physical resources allocated to the UE through the PDCCH, and then the UE can send uplink data on the allocated physical resources. Therefore, in the LTE system, the control channel PDCCH plays a very important role in uplink and downlink scheduling.

One or more pieces of downlink control information (DCI) can be carried on the PDCCH. The content of each DCI includes downlink or uplink scheduling information, or uplink power control commands and the like. There are multiple DCI formats, and the specific DCI format to be used may be determined according to the transmission mode of the UE. A DCI message is transmitted on one or more Control Channel Elements (CCE), a CCE consists of 9 Resource Element Groups (ResourceElement Groups, REG), and a REG contains 4 available Resource Elements ( Resource Element, RE). The format of PDCCH is shown in Table 1 below:

PDCCH format Number of CCEs Number of REGs Number of PDCCH bits 0 1 9 72 1 2 18 144 2 4 36 288 3 8 72 576

Table 1

It can be seen from the above content that the transmission of the PDCCH needs to first determine the format of the PDCCH, that is, determine the number of CCEs occupied by the PDCCH. Usually, the PDCCH format (that is, the number of CCEs occupied by the PDCCH) is determined according to the channel condition, and then rate matching is performed according to the number of CCEs occupied by the PDCCH. When the channel conditions are good, you can configure a PDCCH format that occupies fewer CCEs to increase the code rate of the PDCCH channel, thereby improving the channel utilization of the PDCCH; when the channel conditions are poor, allocate more CCEs to reduce the PDCCH channel The code rate can improve the reliability of transmission, so as to ensure the correct transmission of control information.

When the UE receives the PDCCH signal in the current subframe, it does not know which PDCCH format is used by the network side (eNodeB). Within the scope of the set of PDCCH formats, try to use each PDCCH format for detection.

In order to reduce the complexity of searching, the concept of search space is defined in TS36.213. Each UE searches for control information in a specific search space. Specifically, for subframe k, the search space when the CCE aggregation degree is L defined as:

Formula 1)

in:

N _CCE,k is the number of CCEs included in subframe k.

i=0,...,L-1, L is the CCE aggregation degree, m=0,...,M ^(L) -1, M ^(L) is the number of candidate PDCCHs to be detected in a given search space.

For the common search space: Y _k =0, L=4 or L=8.

For UE-specific search space: L∈{1,2,4,8}, Y _k =(A Y _k-1 )modD, k is the subframe number, Y _-1 =n _RNTI ≠0, A=39827, D=65537.

The position of the PDCCH information on subframe k can be calculated by using the formula (1) when the PDCCH format corresponding to L CCEs is adopted.

At present, there are mainly two methods for detecting the DCI information of the PDCCH channel:

The first method is: decode the PDCCH in the downlink control information format; descramble the decoded PDCCH using the terminal identifier to obtain DCI including the redundancy check code CRC; when the CRC is correct, analyze the The obtained DCI content; when the obtained DCI content is a sequence in which the DCI to be detected does not appear, the subsequent blind detection of the PDCCH is stopped.

The above method traverses different PDCCH formats in a fixed order. Since the number of times of PDCCH blind detection is relatively large, adopting this fixed sequence traversal detection method will result in a long processing time delay of the algorithm and a high computational complexity.

The second method is to use the transmission mode and historical scheduling information configured by the network to the UE to determine the DCI format candidate set of the PDCCH for blind detection, and use the signal-to-noise ratio measurement results and channel changes during two adjacent schedulings to make a preliminary Determine the number of CCE resources carrying the PDCCH (that is, the PDCCH format), and use the initially determined PDCCH format and the DCI format candidate set to perform PDCCH detection.

The above second method first prioritizes the candidate PDCCH formats and then performs blind detection. Compared with the first method, the number of PDCCH blind detection attempts can be reduced, and the calculation efficiency can be improved. However, the above-mentioned second method needs to sort the PDCCH formats according to the measurement result of the noise variance of each subframe, so the accuracy of the noise variance measurement algorithm has a great influence on the algorithm. In addition, the noise variance measurement results reflect the channel status of the PDSCH channel. Due to the different transmission methods and power control methods of the PDSCH and PDCCH channels, the PDSCH noise variance measurement results cannot fully reflect the PDCCH channel status. Therefore, the above-mentioned second method is limited by the accuracy of the noise variance measurement result, and cannot ensure the accuracy of the prioritization of the PDCCH format, and thus cannot effectively improve the blind detection efficiency.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a method for blind detection of physical downlink control channels, which can effectively improve the speed of blind detection.

In order to achieve the above object, the technical scheme proposed by the present invention is:

A method for blind detection of a physical downlink control channel, comprising:

a. After the user equipment UE performs demapping, demodulation and descrambling processing on the PDCCH received signal of the current subframe, according to the CCE aggregation degree used when the downlink control information DCI was detected last time and the downlink allocation index DAI value carried by the DCI, Adjust the search priority of the candidate CCE aggregation degree in the current CCE aggregation degree search candidate set; determine the DCI format candidate set according to the downlink transmission mode of the UE;

b. Select a candidate CCE aggregation degree that is not currently selected and has the highest search priority in the CCE aggregation degree search candidate set as the currently detected CCE aggregation degree; select a DCI format from the DCI format candidate set as the current The detected DCI format;

c. Using the currently detected CCE aggregation degree and the currently detected DCI format, perform decoding and CRC check on the descrambled PDCCH received signal;

d. If the CRC check is correct, then execute step e; otherwise, determine whether there is a DCI format that is not selected under the currently detected CCE aggregation degree in the DCI format candidate set, and if so, select one of the DCI format candidates If the above-mentioned unselected DCI format is used as the currently detected DCI format, perform step c, otherwise, perform step f;

e. According to the CCE aggregation degree corresponding to the currently detected DCI, adjust the search priority of the candidate CCE aggregation degree in the CCE aggregation degree search candidate set, and end the method;

f. Judging whether there is an unselected candidate CCE aggregation degree in the CCE aggregation degree search candidate set, if yes, execute step b, otherwise, end the method.

To sum up, the blind detection method of the physical downlink control channel proposed by the present invention uses the detection status of the PDCCH format and DCI information when the UE detects DCI last time to adjust the detection priority of each PDCCH format in the PDCCH format candidate set , so that the UE can quickly detect DCI information using the correct PDCCH format, thereby reducing the number of PDCCH format attempts during blind detection, improving blind detection efficiency, and reducing UE power consumption.

Description of drawings

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

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

The core idea of the present invention is: in order to avoid the inaccuracy of using the PDSCH noise variance measurement results to perform PDCCH format detection priority ranking in the traditional method, the present invention uses the PDCCH format and DCI information detection situation of the latest DCI detected by the UE to Adjust the detection priority of each PDCCH format in the PDCCH format candidate set, so that the UE can preferentially use the correct PDCCH format to detect DCI information, thereby reducing the number of PDCCH format attempts during blind detection, improving blind detection efficiency, and reducing UE power consumption overhead.

Fig. 1 is a schematic flow chart of Embodiment 1 of the present invention, as shown in Fig. 1, this embodiment mainly comprises:

Step 101: After the UE performs demapping, demodulation and descrambling processing on the PDCCH received signal of the current subframe, according to the CCE aggregation degree used when the DCI information was detected last time and the downlink allocation index (DAI) value carried by the DCI information, Adjusting the search priority of candidate CCE aggregation degrees in the current CCE aggregation degree search candidate set; determining a DCI format candidate set according to the downlink transmission mode of the UE.

In this step, the demapping, demodulation, and descrambling processing of the received signal can be implemented by using existing technologies, which will not be repeated here.

In this step, before performing blind detection, it is necessary to adjust the search priority of the candidate CCE aggregation degrees in the CCE aggregation degree search candidate set according to the last detection situation, so that the search priority of the CCE aggregation degrees with a higher possibility is advanced to reduce The number of blind detection attempts.

Preferably, the following method can be used to adjust the search priority of candidate CCE aggregation degrees in the current CCE aggregation degree search candidate set:

Step 1011, according to d=N _DAI,n -N _DAI,n-1 , calculate the difference d between the DAI values carried by the two latest detected DCI information respectively, where n is the blind value d of the latest currently detected DCI information The detection number, N _DAI,n is the DAI value carried by the DCI information detected for the nth time, and N _DAI,n-1 is the DAI value carried by the DCI information detected for the n-1 time.

Step 1012, when d=1, calculate Δ=Δ+λ ₁ ; when d is greater than 1, calculate Δ=Δ-nλ ₂ ; the λ ₁ is the preset first adjustment step, λ ₁ >0, the λ ₂ is a preset second adjustment step size, and λ ₂ >0.

Here, if d=1, it means that the UE has correctly received a piece of DCI information, and it needs to obtain Δ according to Δ=Δ+λ ₁ ; nλ ₂ to get Δ. In this way, Δ can reflect the latest PDCCH channel status, and the CCE aggregation degree on the network side (eNodeB) is configured according to the current PDCCH channel status. DCI is quickly detected with the correct degree of CCE aggregation.

In practical applications, the _λ1 and _λ2 can be set to appropriate values by those skilled in the art according to actual needs.

Step 1013. When Δ>Γ _max , adjust the aggregation degree of CCEs that are one level lower than the aggregation degree of CCEs corresponding to the nth detection of DCI information to the highest search priority position, and set the CCEs corresponding to the detection of DCI information for the nth time The aggregation degree is adjusted to the second highest search priority position, and the Δ is updated according to Δ=0, and the Γ _max is a preset maximum adjustment threshold.

Here, Δ>Γ _max indicates that the DCI information can basically be received correctly, and the PDCCH channel condition is better. Therefore, the CCE level will be lowered, that is, the CCE aggregation degree of the lower level will be adjusted to the highest search priority position to improve the channel efficiency. utilization rate.

Step 1014, when Δ<Γ _min , adjust the CCE aggregation degree one level higher than the CCE aggregation degree corresponding to the nth detection of DCI information to the highest search priority position, and set the CCE aggregation degree corresponding to the nth detection of DCI information The CCE aggregation degree is adjusted to the second highest search priority position, and the Δ is updated according to Δ=0, the Γ _min is a preset minimum adjustment threshold, and Γ _min ≤ Γ _max .

Here, Δ<Γ _min indicates that the missing detection rate of DCI information is high, and the PDCCH channel condition is poor. Therefore, the level of aggregation degree of the CCE with the highest priority will be increased, that is, the aggregation degree of the higher-level CCE will be adjusted to the highest search priority position.

For the case of Γ _min ≤ Δ ≤ Γ _max , no adjustment is required, and the priority sequence of the CCE polymerization degree obtained after the last detection can be used.

The specific method of determining the DCI format candidate set in step 101 under a given UE downlink transmission mode is known by those skilled in the art, and will not be repeated here.

Step 102: Select a candidate CCE aggregation degree that is not currently selected and has the highest search priority in the CCE aggregation degree search candidate set as the currently detected CCE aggregation degree; select a DCI format from the DCI format candidate set as the The currently detected DCI format.

Step 103: Using the currently detected CCE aggregation degree and the currently detected DCI format, perform decoding and cyclic redundancy check (CRC) on the descrambled PDCCH received signal.

The specific implementation method of this step is within the grasp of those skilled in the art and will not be repeated here.

Step 104 , judging whether the CRC check is correct, if yes, execute step 105 , otherwise, execute step 106 .

Step 105 , according to the CCE aggregation degree corresponding to the currently detected DCI information, adjust the search priority of the candidate CCE aggregation degree in the CCE aggregation degree search candidate set, and end the method.

This step is used to adjust the search priority of candidate CCE aggregation degrees according to the current CCE aggregation degree that can correctly detect DCI, so that the next time the CCE aggregation degree can be preferentially used for blind detection, so as to reduce the number of attempts to detect during detection. frequency.

Preferably, the adjustment in this step can be achieved by the following methods:

Adjust the CCE aggregation degree corresponding to the currently detected DCI information to the highest search priority position.

Step 106 , judging whether there is a DCI format that is not selected under the currently detected CCE aggregation degree in the DCI format candidate set, if yes, execute step 107 ; otherwise, execute step 108 .

This step is used to traverse the DCI formats in the DCI format candidate set for detection under the condition of a given CCE aggregation degree until the DCI can be detected correctly.

Step 107. Select one of the unselected DCI formats as the currently detected DCI format, and execute step 103.

Step 108 , judging whether there is an unselected candidate CCE aggregation degree in the CCE aggregation degree search candidate set, if yes, execute step 102 , otherwise, end the method.

This step is used to trigger traversal of the CCE aggregation degree search candidate set for detection until the DCI can be detected correctly.

To sum up, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (3)

1. A blind detection method of a physical downlink control channel, characterized in that, comprising: a. After the user equipment UE demaps, demodulates and descrambles the received signal of the physical downlink control channel PDCCH in the current subframe, according to the control channel cell CCE aggregation degree and the DCI used when the downlink control information DCI was detected last The carried downlink allocation index DAI value adjusts the search priority of the candidate CCE aggregation degree in the current CCE aggregation degree search candidate set; determines the DCI format candidate set according to the downlink transmission mode of the UE; b. Select a candidate CCE aggregation degree that is not currently selected and has the highest search priority in the CCE aggregation degree search candidate set as the currently detected CCE aggregation degree; select a DCI format from the DCI format candidate set as the current The detected DCI format; c. Using the currently detected CCE aggregation degree and the currently detected DCI format, perform decoding and cyclic redundancy check (CRC) inspection on the descrambled PDCCH received signal; d. If the CRC check is correct, then execute step e; otherwise, determine whether there is a DCI format that is not selected under the currently detected CCE aggregation degree in the DCI format candidate set, and if so, select one of the DCI format candidates If the above-mentioned unselected DCI format is used as the currently detected DCI format, perform step c, otherwise, perform step f; e. According to the CCE aggregation degree corresponding to the currently detected DCI, adjust the search priority of the candidate CCE aggregation degree in the CCE aggregation degree search candidate set, and end the method; f. Judging whether there is an unselected candidate CCE aggregation degree in the CCE aggregation degree search candidate set, if yes, execute step b, otherwise, end the method. 2. The method according to claim 1, characterized in that, adjusting the search priority of the candidate CCE aggregation degree in the current CCE aggregation degree search candidate set in step a comprises: According to d=N _DAI,n -N _DAI,n-1 , calculate the difference d between the DAI values carried by the two latest DCI information respectively, where n is the blind detection number of the latest DCI detected at present, N _DAI,n is the DAI value carried by the DCI detected for the nth time, N _DAI,n-1 is the DAI value carried by the DCI detected for the n-1th time; When d=1, calculate Δ=Δ+λ ₁ ; when d is greater than 1, calculate Δ=Δ-nλ ₂ ; the λ ₁ is the preset first adjustment step, λ ₁ >0 , the λ ₂ is the preset second adjustment step size, λ ₂ >0; When Δ>Γ _max , adjust the CCE aggregation degree one level lower than the CCE aggregation degree corresponding to the nth detection of DCI to the highest search priority position, and adjust the CCE aggregation degree corresponding to the nth detection of DCI to the second A high search priority position, and update the Δ according to Δ=0; the Γ _max is the preset maximum adjustment threshold; When Δ<Γ _min , adjust the CCE aggregation degree one level higher than the CCE aggregation degree corresponding to the nth detection of DCI to the highest search priority position, and adjust the CCE aggregation degree corresponding to the nth detection of DCI to The second highest priority position is searched, and the Δ is updated according to Δ=0, the Γ _min is a preset minimum adjustment threshold, and Γ _min ≤ Γ _max . 3. The method according to claim 1, wherein the adjustment in the step h comprises: Adjust the CCE aggregation degree corresponding to the currently detected DCI to the highest search priority position.