CN110708149A - Method and device for determining downlink MCS - Google Patents

Abstract

The present application provides a method and device for determining a downlink MCS. The method includes: for a user accessing a cell, assigning a corresponding coverage level to the user according to the distribution of the users; for any user, in a preset statistical window, if It is determined that the number of NACKs fed back by the user is greater than the first preset threshold, then the channel quality indicator CQI of the user is adjusted downward by a first preset step size; if it is determined that the number of ACKs fed back by the user is greater than the second preset threshold, Then adjust the CQI of the user upward by a second preset step size; if it is determined that the CQI of the user has been adjusted, use the adjusted CQI to determine the corresponding downlink MCS; wherein the preset statistics window, the first preset threshold , the values of the second preset threshold, the first preset step size and the second preset step size are configured according to the coverage level. The method can improve the user's transmission accuracy, user throughput and transmission efficiency.

Description

A kind of downlink MCS determination method and device

technical field

The present invention relates to the field of communication technologies, and in particular, to a method and device for determining a downlink MCS.

Background technique

A very important feature of wireless channels is that they have strong time variability, and the fading can reach ten or even tens of dB in a short period of time. The transmission efficiency of the communication system is greatly improved.

The basic principle is to estimate the channel of data transmission at the receiving end and feed it back to the transmitting end, so that the transmitting end can select the corresponding modulation and coding strategy (MCS) for data transmission according to the characteristics of the channel, so as to improve the overall throughput of the system. volume and transmission efficiency.

The downlink MCS selection method is to measure and report the CQI according to the channel quality indicator (CQI, Channel Quality Indicator) reporting mechanism, and convert the reported value of the CQI into the corresponding Signal to Interference plus Noise Ratio (SINR) according to the CQI mapping table. Noise Ratio), and then select the downlink MCS according to the SINR.

The downlink MCS determination is to determine the MCS based on the CQI reporting result. Once the CQI estimation is inaccurate, the determined MCS will be inaccurate.

In addition, because users are distributed in different positions of the cell, the deviation degrees of CQI estimation results of different users are different. If the CQI is adjusted according to a unified method, the selected MCS will also be inaccurate. This not only affects the transmission efficiency of the user, but also affects the overall throughput of the cell.

SUMMARY OF THE INVENTION

In view of this, the present application provides a method and apparatus for determining a downlink MCS, which can improve the user's transmission accuracy, user throughput and transmission efficiency.

In order to solve the above-mentioned technical problems, the technical solution of the present application is realized as follows:

A method for determining a downlink modulation and coding strategy MCS, the method comprising:

For users accessing the cell, assign the corresponding coverage level to the user according to the distribution of the users;

For any user, count the feedback results of the user's negative NACK and confirmed ACK in the preset statistics window;

If it is determined that the number of NACKs fed back by the user is greater than the first preset threshold, the channel quality indicator CQI of the user is adjusted downward by a first preset step size;

If it is determined that the number of ACKs fed back by the user is greater than the second preset threshold, the CQI of the user is adjusted upward by a second preset step size;

If it is determined that the CQI of the user has been adjusted, the adjusted CQI is used to determine the corresponding downlink MCS;

The values of the preset statistics window, the first preset threshold, the second preset threshold, the first preset step size, and the second preset step size are configured according to the coverage level.

in,

The distribution of users includes near-point distribution, mid-point distribution and far-point distribution.

in,

The distribution of users is determined according to the value of the reference signal received power RSRP or the signal-to-interference-plus-noise ratio SINR.

in,

When it is determined that the number of NACKs fed back by the user is greater than the first preset threshold, the method further includes: determining whether the CQI of the user has reached the minimum CQI value, and if so, not adjusting the CQI of the user; The channel quality of the user indicates that the CQI is adjusted downward by the first preset step size;

When it is determined that the number of ACKs fed back by the user is greater than the second preset threshold, the method further includes: determining whether the CQI of the user has reached the maximum CQI value, and if so, do not adjust the CQI of the user; The user's CQI is adjusted upward by a second preset step size.

A device for determining a downlink modulation and coding strategy MCS, the device comprising: an allocation unit, a statistics unit, an adjustment unit and a determination unit;

The assigning unit is configured to assign a corresponding coverage level to a user accessing the cell according to the distribution of the user; configure a preset statistical window, a first preset threshold, a second preset threshold, a first preset threshold, and a third preset threshold according to the coverage level. a preset step size and a second preset step size;

The statistical unit is configured to, for any user, count the feedback results of the negative NACK and the confirmed ACK of the user in a preset statistical window configured by the allocation unit;

The adjustment unit is configured to adjust the channel quality indicator CQI of the user downward to adjust the configuration of the allocation unit downward if the number of NACKs fed back by the user is determined by the statistics unit to be greater than the first preset threshold configured by the allocation unit If it is determined that the number of ACKs fed back by the user is greater than the second preset threshold configured by the allocation unit, then the CQI of the user is adjusted upward by the second preset step size configured by the allocation unit ;

The determining unit is configured to use the adjusted CQI to determine the corresponding downlink MCS if it is determined that the adjusting unit has adjusted the CQI of the user.

in,

The distribution of users includes near-point distribution, mid-point distribution and far-point distribution.

in,

The distribution of users is determined according to the value of the reference signal received power RSRP or the signal-to-interference-plus-noise ratio SINR.

in,

The adjustment unit is further configured to determine whether the CQI of the user has reached the minimum value of the CQI if it is determined that the number of NACKs fed back by the user is greater than the first preset threshold, and if so, do not adjust the CQI of the user; The channel quality of the user indicates that the CQI is adjusted downward by the first preset step size; if it is determined that the number of ACKs fed back by the user is greater than the second preset threshold, it is determined whether the CQI of the user has reached the maximum CQI value, and if so, no Adjust the CQI of the user; otherwise, adjust the CQI of the user upward by a second preset step size.

As can be seen from the above technical solutions, in this application, considering the factors of different CQI deviations reported by users with different coverage levels, the number of acknowledgments (NACKs) and acknowledgments (ACKs) fed back to users with different coverage levels is preset. The statistical window determines whether to adjust the CQI periodically. If the CQI is adjusted for any user, the adjusted CQI is used to determine the downlink MCS. This solution can improve the user's transmission accuracy, user throughput and transmission efficiency.

Description of drawings

1 is a schematic flowchart of determining a downlink MCS in an embodiment of the present application;

FIG. 2 is a schematic structural diagram of an embodiment of the present application applied to the above-mentioned device.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

A method for determining a downlink MCS is provided in the embodiment of the present application. Considering factors of different CQI deviations reported by users with different coverage levels, the number of acknowledgments (NACKs) and acknowledgments (ACKs) fed back to users with different coverage levels is based on the number of acknowledgments (NACKs). Whether to adjust the CQI is determined by taking the preset statistical window as a period, and if the CQI is adjusted for any user, the adjusted CQI is used to determine the downlink MCS. This solution can improve the user's transmission accuracy, user throughput and transmission efficiency.

When the embodiments of the present application are specifically implemented, for users accessing a cell, corresponding coverage levels are allocated to the users according to the distribution of the users.

The distribution of users may include, but is not limited to, near-point distribution, mid-point distribution, and far-point distribution. Specifically, it refers to the distance between the user and the base station. According to the user distribution, there may be but not limited to three corresponding levels: one level corresponds to the near point distribution, one level corresponds to the midpoint distribution, and one level corresponds to the far point distribution; the farther away from the base station, the greater the coverage level.

The values of the preset statistics window, the first preset threshold, the second preset threshold, the first preset step size and the second preset step size are configured according to the coverage level.

In the actual application environment, the farther the distance from the base station is, the less accurate the reported or measured CQI will be. At this time, it is necessary to set a smaller preset statistics window, first preset threshold, second preset threshold, first preset threshold and first preset threshold for the coverage level. Set the step size and the second preset step size to be smaller. That is, the values of the preset statistical window, the first preset threshold, the second preset threshold, the first preset step size, and the second preset step size may be smaller as the coverage level increases.

The distribution of users is determined according to a reference signal received power (Reference Signal Receiving Power, RSRP) or a signal to interference plus noise ratio (Signal to Interference plus Noise Ratio, SINR) value.

Among them, RSRP is one of the key parameters that can represent the wireless signal strength and one of the physical layer measurement requirements in the LTE network. It is the average value of the signal power received on all resource elements (REs) carrying reference signals in a certain symbol. The acquisition of the value may be implemented according to the existing implementation, which is not limited in this embodiment of the present application.

SINR refers to the ratio of the strength of the received useful signal to the strength of the received interference signal (noise and interference); it can be simply understood as "signal-to-noise ratio". This example is not restricted.

The following describes the process of determining the downlink MCS in the embodiments of the present application in detail with reference to the accompanying drawings.

Referring to FIG. 1, FIG. 1 is a schematic flowchart of determining a downlink MCS in an embodiment of the present application. The specific steps are:

Step 101: For any user, the base station counts the feedback results of the user's NACK and ACK in a preset statistical window.

The preset statistics window window in this step is configured according to the coverage level corresponding to the user, and different values can be set for different coverage levels.

Step 102, if the base station determines that the number of NACKs fed back by the user is greater than a first preset threshold, adjust the CQI of the user downward by a first preset step size.

In this step, if it is determined that the number of NACKs fed back by the user is greater than the first preset threshold, the step further includes: determining whether the CQI of the user has reached the minimum CQI value, and if so, do not adjust the CQI of the user; The channel quality indicates that the CQI is adjusted downward by the first preset step size.

If the current CQI of the user has reached the minimum value, even if the number of NACKs fed back by the user is greater than the first preset threshold, the CQI of the user will not be adjusted downward.

Step 103: If the base station determines that the number of ACKs fed back by the user is greater than a second preset threshold, the base station adjusts the user's CQI upward by a second preset step size.

In this step, if it is determined that the number of ACKs fed back by the user is greater than the second preset threshold, the method further includes: determining whether the CQI of the user has reached the maximum CQI value, and if so, do not adjust the CQI of the user; The CQI is adjusted upward by the second preset step size.

The first preset threshold may be the product of the lower threshold CQI_down_th and the preset statistics window window; the second preset threshold may be the product of the increase threshold CQI_up_th and the preset statistics window window.

The first preset threshold and the second preset threshold may be the same or different.

The first preset step size, that is, the downward adjustment step CQI_down_N and the second preset step size, that is, the second adjustment step CQI_up_N, may be the same or different.

In this embodiment of the present application, step 102 and step 103 cannot be in sequence, and cannot necessarily occur, and it is determined whether they occur according to specific circumstances.

One of the steps may be performed, none of the steps may be performed, or both steps may be performed.

Step 104, if the base station determines that the CQI of the user has been adjusted in the current preset statistical window, the base station uses the adjusted CQI to determine the corresponding downlink MCS.

If the base station determines that the CQI of the user has not been adjusted in the current preset statistics window, it does not re-determine the downlink MCS.

The downlink UE maps the measured CRS SINR to the CQI and reports it to the base station (eNB).

The uplink eNB obtains the uplink CQI through DMRS or SRS measurement.

For the CQI (full-band or sub-band) or uplink CQI reported by the UE, the eNB determines the SINR according to the CQI mapping table, and then determines the downlink MCS according to the SINR.

The eNB sends the determined MCS to the UE through the PDCCH, and the UE can look up the table to obtain the modulation mode and TBS according to the MCS, and perform downlink demodulation or uplink modulation. The eNB accordingly performs downlink modulation and uplink demodulation according to the MCS.

What is improved in the embodiment of this application is to adjust the CQI reported by the UE or measured by the base station, and then determine the MCS after the adjustment. If it is determined that the CQI has been adjusted in any preset statistical window, that is, the MCS changes, it will be downloaded again through the PDCCH. sent to the UE.

In the specific implementation of this application, for a user, different coverage levels may be assigned in different time periods, and for different coverage levels, the preset statistical window, adjustment step size and preset threshold configured for the corresponding coverage level are used to perform CQI adjustment.

During specific implementation, the above method is used to determine the downlink MCS for each user. During specific implementation, the method provided by the present application will always be used to adjust the CQI after the user accesses, and during the specific adjustment, the adjustment may be performed one by one statistical window.

After the statistical adjustment of the current preset statistics window is completed, slide the preset statistics window backward, continue to count the number of NACKs and ACKs in the sliding preset statistics window to determine whether to adjust the CQI, and count NACKs in the new statistics window. When the number of NACKs and ACKs is equal to the number of ACKs, the number of NACKs and ACKs counted in the last preset statistics window needs to be cleared.

Based on the same inventive concept, the present application also proposes an apparatus for determining a downlink MCS. Referring to FIG. 2, FIG. 2 is a schematic structural diagram of an embodiment of the present application applied to the above-mentioned device. The apparatus includes: an allocation unit 201, a statistics unit 202, an adjustment unit 203 and a determination unit 204;

The allocation unit 201 is configured to allocate a corresponding coverage level to a user accessing a cell according to the distribution of the user; configure a preset statistical window, a first preset threshold, a second preset threshold, a first preset threshold according to the coverage level a preset step size and a second preset step size;

The statistical unit 202 is configured to, for any user, count the feedback results of the negative NACK and the confirmed ACK of the user in the preset statistical window configured by the allocation unit 201;

The adjustment unit 203 is configured to adjust the channel quality indicator CQI of the user downward to the first preset threshold configured by the distribution unit 201 if the statistics unit 202 determines that the number of NACKs fed back by the user is greater than the first preset threshold configured by the distribution unit 201 . Set the step size; if it is determined that the number of ACKs fed back by the user is greater than the second preset threshold configured by the allocation unit 201, then the CQI of the user is adjusted upwards by the second preset step size configured by the allocation unit 201;

The determining unit 204 is configured to use the adjusted CQI to determine the corresponding downlink MCS if it is determined that the adjusting unit 203 has adjusted the CQI of the user.

Preferably,

The distribution of users includes near-point distribution, mid-point distribution and far-point distribution.

Preferably,

The distribution of users is determined according to the value of the reference signal received power RSRP or the signal-to-interference-plus-noise ratio SINR.

Preferably,

The adjustment unit 203 is further configured to determine whether the CQI of the user has reached the minimum value of the CQI if it is determined that the number of NACKs fed back by the user is greater than the first preset threshold, and if so, do not adjust the CQI of the user; The channel quality of the user indicates that the CQI is adjusted downward by the first preset step size; if it is determined that the number of ACKs fed back by the user is greater than the second preset threshold, it is determined whether the CQI of the user has reached the maximum CQI value, and if so, do not adjust CQI of the user; otherwise, the CQI of the user is adjusted upward by a second preset step size.

The units in the foregoing embodiments may be integrated into one body, or may be deployed separately; may be combined into one unit, or may be further split into multiple subunits.

To sum up, by considering the factors of different CQI deviations reported by users with different coverage levels, the present application uses a preset statistical window for the number of acknowledgments (NACKs) and acknowledgments (ACKs) fed back by users with different coverage levels. In order to periodically determine whether to adjust the CQI, if the CQI is adjusted for any user, the adjusted CQI is used to determine the downlink MCS. This solution can improve the user's transmission accuracy, user throughput and transmission efficiency.

Specifically:

The coverage levels of different users in the cell are distinguished;

Adopt different CQI adjustment strategies for different coverage levels of users;

Improve the transmission accuracy of users with poor coverage levels (users far from the base station);

Improve the transmission throughput of users with good coverage levels (users close to the base station).

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

Claims (8)

1. a downlink modulation and coding strategy MCS determination method, is characterized in that, the method comprises: For users accessing the cell, assign the corresponding coverage level to the user according to the distribution of the users; For any user, count the feedback results of the user's negative NACK and confirmed ACK in the preset statistics window; If it is determined that the number of NACKs fed back by the user is greater than the first preset threshold, the channel quality indicator CQI of the user is adjusted downward by a first preset step size; If it is determined that the number of ACKs fed back by the user is greater than the second preset threshold, the CQI of the user is adjusted upward by a second preset step size; If it is determined that the CQI of the user has been adjusted, the adjusted CQI is used to determine the corresponding downlink MCS; The values of the preset statistics window, the first preset threshold, the second preset threshold, the first preset step size, and the second preset step size are configured according to the coverage level. 2 . The method according to claim 1 , wherein the distribution of users includes near-point distribution, mid-point distribution and far-point distribution. 3 . 3. The method according to claim 1, wherein The distribution of users is determined according to the value of the reference signal received power RSRP or the signal-to-interference-plus-noise ratio SINR. 4. The method according to any one of claims 1-3, wherein, When it is determined that the number of NACKs fed back by the user is greater than the first preset threshold, the method further includes: determining whether the CQI of the user has reached the minimum CQI value, and if so, not adjusting the CQI of the user; The channel quality of the user indicates that the CQI is adjusted downward by the first preset step size; When it is determined that the number of ACKs fed back by the user is greater than the second preset threshold, the method further includes: determining whether the CQI of the user has reached the maximum CQI value, and if so, do not adjust the CQI of the user; The user's CQI is adjusted upward by a second preset step size. 5. A device for determining a downlink modulation and coding strategy MCS, characterized in that the device comprises: an allocation unit, a statistics unit, an adjustment unit and a determination unit; The assigning unit is configured to assign a corresponding coverage level to a user accessing the cell according to the distribution of the user; configure a preset statistical window, a first preset threshold, a second preset threshold, a first preset threshold, and a third preset threshold according to the coverage level. a preset step size and a second preset step size; The statistical unit is configured to, for any user, count the feedback results of the negative NACK and the confirmed ACK of the user in a preset statistical window configured by the allocation unit; The adjustment unit is configured to adjust the channel quality indicator CQI of the user downward to adjust the configuration of the allocation unit downward if the number of NACKs fed back by the user is determined by the statistics unit to be greater than the first preset threshold configured by the allocation unit If it is determined that the number of ACKs fed back by the user is greater than the second preset threshold configured by the allocation unit, then the CQI of the user is adjusted upward by the second preset step size configured by the allocation unit ; The determining unit is configured to use the adjusted CQI to determine the corresponding downlink MCS if it is determined that the adjusting unit has adjusted the CQI of the user. 6 . The device according to claim 5 , wherein the distribution of users includes near-point distribution, mid-point distribution and far-point distribution. 7 . 7. The device of claim 5, wherein The distribution of users is determined according to the value of the reference signal received power RSRP or the signal-to-interference-plus-noise ratio SINR. 8. The device according to any one of claims 4-7, characterized in that, The adjustment unit is further configured to determine whether the CQI of the user has reached the minimum value of the CQI if it is determined that the number of NACKs fed back by the user is greater than the first preset threshold, and if so, do not adjust the CQI of the user; The channel quality of the user indicates that the CQI is adjusted downward by the first preset step size; if it is determined that the number of ACKs fed back by the user is greater than the second preset threshold, it is determined whether the CQI of the user has reached the maximum CQI value, and if so, no Adjust the CQI of the user; otherwise, adjust the CQI of the user upward by a second preset step size.

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