A method and a base station for uplink closed loop power control on the base station side

Abstract

Embodiments of the present application disclose a method and a base station for uplink closed loop power control on the side of the base station. The method comprises: obtaining a current channel state of a user terminal (UE); determining a transmit power control (TPC) command value of the UE according to the channel state; and obtaining a PUSCH transmit power adjustment amount according to TPC information corresponding to the determined TPC command value.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of mobile communications, and in particular to a method and a base station for uplink closed-loop power control on a base station side. Background Art

[0002] Wireless networks are the foundation and guarantee of mobile communications, and are of great significance to the promotion of mobile services, user experience, and customer perception. Power control has a great impact on ensuring link quality and reducing interference. The key channels involved in power control in the uplink of 5G wireless systems include PUCCH (Physical Uplink Control Channel), PUSCH (Physical Uplink Shared Channel), and SRS (Sounding Reference Signal). Through reasonable and effective power control optimization, the quality of these channels can be improved, thereby effectively improving the rate experience. Generally speaking, when the uplink channel quality decreases, the system will instruct the UE to increase the transmit power as needed. When the uplink channel quality increases, the system will instruct the UE to reduce the transmit power as needed.

[0003] 5G wireless systems use two different uplink power control mechanisms: open-loop power control and closed-loop power control. Uplink open-loop power control involves the UE adjusting its uplink power based on measurement information, without the need for base station involvement. Uplink closed-loop power control involves the base station sending transmit power control commands (TPCs) to adjust the UE's transmit power, requiring base station involvement. Open-loop power control can compensate for long-term channel variations, thereby improving power control performance. Closed-loop power control can compensate for rapid channel variations, thereby improving power control performance.

[0004] In 3GPP (3rd Generation Partnership Project), when a UE transmits only the PUSCH channel in time slot i, the power control calculation expression of the UE in the PUSCH channel in time slot i is as follows:

[0005]

[0006] in:

[0007] P CMAX,f,c (i) represents the maximum transmission power configured by the UE;

[0008] P O_PUSCH,b,f,c (j) represents the nominal power;

[0009] Indicates the number of RBs occupied by the PUSCH channel in one transmission time slot;

[0010] PL b,f,c (q d ) represents the downlink path loss estimated by the UE based on the reference signal;

[0011] Δ TF,b,f,c (i) represents the MCS power offset value of different MCS formats relative to the reference MCS;

[0012] f b,f,c (i, l) represents the PUSCH transmit power adjustment amount of the UE, which is obtained by mapping the TPC information in the PDCCH (Physical Downlink Control Channel).

[0013] In the power control process of the PUSCH channel, the base station side sets the nominal power P O_PUSCH,b,f,c (j) After being configured to the UE, this value will not be adjusted again, so the open-loop power adjustment is reflected in the nominal power P O_PUSCH,b,f,c (j). And for f b,f,c (i, l), the base station needs to dynamically adjust its value through the TPC command in the PDCCH, so the uplink closed-loop power control is reflected in the UE's PUSCH transmit power adjustment amount f b,f,c (i, l), for the UE's PUSCH transmit power adjustment amount f b,f,c (i, l), whose value changes depend on the TPC command value. In existing technologies, the TPC command value is adjusted solely based on changes in the uplink signal-to-noise ratio (SNR). However, the uplink SNR is the ratio of the useful signal to the noise, and its value does not reflect the impact of interference on uplink power adjustment. As a result, UEs with varying, even significantly varying, interference levels are often configured with the same TPC command value, resulting in the same transmit power adjustment amount, wasting energy. Summary of the Invention

[0014] In order to solve any of the above technical problems, an embodiment of the present application provides a method for uplink closed-loop power control on a base station side and a base station.

[0015] To achieve the purpose of the embodiments of the present application, the embodiments of the present application provide a method for uplink closed-loop power control on a base station side, including:

[0016] Obtain the current channel status of the user terminal UE;

[0017] Determine a transmit power control command TPC command value of the UE according to the channel state;

[0018] A PUSCH transmit power adjustment amount is obtained according to TPC information corresponding to the determined TPC command value.

[0019] A base station executes the method described above.

[0020] One of the above technical solutions has the following advantages or beneficial effects:

[0021] The channel status between the UE and the base station is fully considered to determine the TPC command value of each UE, thereby determining the PUSCH transmit power adjustment amount corresponding to each UE, thereby adjusting the uplink closed-loop power to ensure the channel status between the UE and the base station, further reducing the total system power and effectively saving energy.

[0022] Other features and advantages of the embodiments of the present application will be described in the following description, and in part will become apparent from the description or be understood by practicing the embodiments of the present application. The objectives and other advantages of the embodiments of the present application can be achieved and obtained through the structures particularly pointed out in the description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the technical solutions of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the embodiments of the present application, they are used to explain the technical solutions of the embodiments of the present application and do not constitute a limitation on the technical solutions of the embodiments of the present application.

[0024] Figure 1 Flowchart of the method for uplink closed-loop power control on the base station side provided in Example 1 of the present application;

[0025] Figure 2 This is a flowchart of the method for uplink closed-loop power control on the base station side provided in Example 2 of the present application. DETAILED DESCRIPTION

[0026] To make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the embodiments of the present application will be described in detail below with reference to the accompanying drawings. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of the present application can be combined with each other in any way.

[0027] To solve the above problems, the present invention provides a method for uplink closed-loop power control at the base station side, which determines the TPC command value of each UE based on the channel state of each UE, thereby determining the PUSCH transmission power adjustment amount f corresponding to each UE. b,f,c (i,l), thereby adjusting the uplink closed-loop power.

[0028] Example 1:

[0029] like Figure 1 As shown, the present invention provides a method for uplink closed-loop power control on the base station side, which determines the TPC command value of each UE based on the channel state of each UE, wherein: the channel state between the UE and the base station includes: the current SNR of the transmission channel where the UE is located and the current uplink level interference NI value of the UE. According to the channel state of the UE, different TPC command values ​​are configured for different UEs, and the PUSCH transmission power adjustment value f of different UEs obtained by TPC information mapping is obtained. b,f,c (i, l). In this way, after the UE access process, the base station configures different uplink closed-loop powers for different UEs. The specific method is as follows:

[0030] S1: The base station obtains the SNR value of the transmission channel where each UE in the cell is located, and determines the channel quality coefficient α that represents the current channel quality based on the obtained SNR value SNR ;

[0031] In this step, the SNR value can be obtained using the existing technology, for example, by demodulating uplink data at the physical layer. The effective working value range of SNR is [-10, 40] dB, which is consistent with most scenarios in the existing technology. The processing method for the SNR value outside this range is not involved in the technical solution of this application;

[0032] In this step, the channel quality coefficient α SNR Characterizes the current channel quality, which is determined by the SNR value of the channel where the UE is located. When the SNR is larger, the channel quality is better. The channel quality coefficient α SNR The larger the SNR, the worse the channel quality. SNR The smaller;

[0033] Typically, the channel quality factor α SNR This can be determined by:

[0034] The effective working range of SNR is divided into multiple SNR sub-ranges according to the set rules, and each SNR sub-range corresponds to a channel quality coefficient α SNR The rules described are for ordinary technicians in this field to define different quality attributes of the channel where the UE is located according to the application scenario. In fact, for different UEs, the quality attributes of the channel may be different. Since the SNR value directly represents the channel quality of the channel, different sub-intervals can be directly defined according to the SNR value to distinguish the channel quality of the channels where different UEs are located. Typically, as shown in Table 1 below, the SNR effective working interval can be divided into four SNR sub-intervals, corresponding to different channel quality attributes of the UE: excellent point, good point, medium point and poor point; a channel quality coefficient α is determined for each of the four defined intervals. SNR , and the channel quality coefficient αSNR It increases as the maximum value of each SNR sub-interval increases.

[0035]

[0036]

[0037] Table 1

[0038] Of course, in the embodiment of the present application, the location attributes of the UE are not necessarily the excellent point, good point, midpoint, and poor point listed in the above examples, and there may be only three of them: good point, midpoint, and poor point; they can be determined by ordinary technicians in this field based on the system scenario; the two extreme values ​​of each SNR sub-interval are selected by ordinary technicians in this field based on design requirements.

[0039] Furthermore, due to the channel quality coefficient α SNR Characterizes the current channel quality, and its interval is usually selected as [0, 1]. Of course, in other embodiments, a sub-interval in [0, 1] can also be used. This is not specifically limited here and can be selected by ordinary technicians in this field. At the same time, since the channel quality coefficient α SNR The value gradually increases as the maximum value of each sub-interval increases from small to large. Therefore, the value can be evenly divided and reduced according to the number of intervals. For example, the step size in Table 1 is -0.1. Of course, other methods are also possible, but the above typical values ​​can be applied to most scenarios without special settings.

[0040] S2: The base station obtains the current uplink interference level NI value of each UE in the cell, and determines the interference coefficient α that represents the interference size based on the obtained NI value NI ;

[0041] In existing wireless communication systems, NI is obtained when the physical layer demodulates uplink data. It is usually in the range of [-130, 0] dB. A larger NI value indicates greater interference, and a smaller NI value indicates less interference.

[0042] In this step, the interference coefficient α NI Characterizes the interference level to compensate for the change in required power due to interference. It can be reduced synchronously from small to large interference to the base station. Typically, it can be determined by:

[0043] The NI value is divided into multiple intervals according to the set rules. The rules are different interference levels of NI defined by ordinary technicians in this field according to the application scenario. In the embodiment of the present application, different intervals can be directly defined according to the NI value. Typically, as shown in Table 2 below, NI can be divided into five intervals corresponding to different interference levels, namely excellent, good, medium, poor and very poor; each NI value interval corresponds to an interference coefficient αNI ;

[0044]

[0045]

[0046] Table 2

[0047] In this step, the interference coefficient α NI The interval of NI is usually selected as [0, 1]. Of course, in other embodiments, a sub-interval of [0, 1] may also be used. This is not specifically limited here and can be selected by those skilled in the art. For example, [0.6, 1] shown in Table 2 above can meet the needs of most scenarios. Furthermore, for the interference coefficient α corresponding to each NI interval, NI , since the smaller the interference value, the larger the coverage range, the interference coefficient α NI can be smaller, therefore, the interference coefficient α NI As the interference value changes from large to small, it increases. It can be divided and reduced evenly according to the number of intervals divided between the extreme values ​​of the interval. For example, the step size of Table 2 is -0.1; of course, the compensation can also be other values, the interference coefficient α NI The interference value may be reduced in other ways, but the above typical values ​​can be applied to most scenarios without special settings.

[0048] S3: The base station uses the channel quality coefficient α SNR and interference coefficient α NI Determine a channel quality reference value θ corresponding to each UE in the cell;

[0049] Specifically, according to the formula θ=(α SNR +α NI ) / 2 determines the channel quality reference value θ corresponding to each UE in the cell;

[0050] In this step, the channel level is combined with the channel quality coefficient α SNR and interference coefficient α NI As determined, it reflects the joint influence of SNR and NI;

[0051] S4: The base station determines a TPC command value according to the determined channel quality reference value θ, and sends it to the corresponding UE, so that the UE can adjust the PUSCH uplink power.

[0052] In the prior art, there are generally two methods for determining the TPC value: cumulative and absolute. The cumulative method means that the current power adjustment value is the value of the previous power adjustment plus / minus one adjustment step indicated in the TPC. The TPC adjustment step in the cumulative method is (-1, 0, 1, 3) dB. The absolute method directly uses the power adjustment value indicated in the TPC. The TPC adjustment step is (-4, -1, 1, 4) dB. The size of the compensation value is determined by the value in the TCP command field. Different adjustment methods use different delivery methods. The cumulative method is indicated by DCI format 0 / 3, while the absolute method requires the base station to explicitly disable the cumulative method through RRC signaling.

[0053] In this step, the TPC command value is determined based on the determined channel quality reference value θ. Specifically, different channel level intervals within which the channel quality reference value θ is located correspond to different TPC command values. Typically, since there are four TPC command values, each corresponding to a different adjustment value, four corresponding channel level intervals are also set. The size of each interval can be determined by a person skilled in the art according to actual conditions. However, the adjustment step value increases with an increase in the extreme value of the corresponding interval.

[0054] Typically, the TPC command value can be set using the method shown in Table 3:

[0055] Channel quality reference value TPC command value <![CDATA[θ2≤θ≤θ1]]> 0 <![CDATA[θ3≤θ<θ2]]> 1 <![CDATA[θ4≤θ<θ3]]> 2 <![CDATA[θ5≤θ<θ4]]> 3

[0056] Table 3

[0057] Among them: the values ​​of θ1, θ2, θ3, θ4, and θ5 can be determined by ordinary technicians in this field according to the scenario so that they constitute different channel quality reference intervals, but typically they can be: θ1=1, θ2=0.9, θ3=0.8, θ4=0.7, θ5=0.6, which can meet most non-special application scenarios.

[0058] Through the above method, it can be seen that: for UEs in a cell, when changing the uplink closed-loop power through the TPC command value, the channel quality of the transmission channel where the UE is located and the current uplink interference level of the UE can be fully considered. Different TPC command values ​​are determined for different situations, so that the uplink power can be adjusted. While meeting the link connection requirements of each UE and the base station, the total system power can also be reduced, effectively saving energy.

[0059] Example 2:

[0060] In existing networks, bit errors are a significant factor affecting signal transmission quality. Signals decay during transmission between the UE and the base station, changing the signal voltage and causing signal damage during transmission, leading to bit errors. Pulses caused by external factors such as noise and AC current can also cause bit errors. Therefore, the UE's uplink power is directly affected by the bit error rate.

[0061] Based on this, the second embodiment of the present application provides a method for uplink closed-loop power control, such as Figure 2 As shown, the channel status between the UE and the base station includes: the current SNR of the transmission channel where the UE is located, the current uplink interference level NI value of the UE, and the current BLER (Block Error Rate) reported by the UE. Different TPC command values ​​are configured for different UEs according to the UE channel status. The PUSCH transmit power adjustment value f of different UEs obtained by TPC information mapping is b,f,c (i, l). In this way, after the UE accesses, the base station can configure different uplink closed-loop powers for different UEs. The specific method is as follows:

[0062] S11: The base station obtains the SNR value of the transmission channel where each UE in the cell is located, and the current BLER reported by each UE in the cell;

[0063] In this step, the SNR value can be obtained using the existing technology, for example, by demodulating uplink data at the physical layer. The effective working value range of SNR is [-10, 40] dB, which is consistent with most scenarios in the existing technology. The processing method for the SNR value outside this range is not involved in the technical solution of this application;

[0064] In this step, the base station may start a BLER monitoring cycle according to a preset policy, and at the end of a monitoring cycle, record the BLER obtained in the monitoring cycle as the current BLER. The preset policy here may be a startup policy in the prior art. For example, when determining that a certain UE has accessed, the base station starts the first BLER monitoring cycle for the UE, and the initial value of the current BLER at this time is set to 0.

[0065] S12: The base station obtains the current uplink interference level NI value of each UE in the cell;

[0066] In existing wireless communication systems, NI is obtained when the physical layer demodulates uplink data. It is usually in the range of [-130, 0] dB. A larger NI value indicates greater interference, and a smaller NI value indicates less interference.

[0067] S13: The base station determines an equivalent SNR (SNR) based on the current BLER and the current NI value. equ );

[0068] Specifically, the following calculation expression is used to determine the SNR equ ,include:

[0069] SNR equ =SNR-ΔBLER / tergetBLER*ΔNI

[0070] Among them, SNR equ is the equivalent SNR, BLER is the current BLER, NI is the current NI value, ΔBLER=BLER-targetBLER, ΔNI=NI-(-130), and targetBLER is the preset target BLER.

[0071] In NR, the target BLER is typically set to 10%, meaning that the bit error rate does not exceed 10% in the absence of HARQ retransmission. Of course, in other embodiments, the target BLER may be set to other values ​​based on actual conditions. For example, in situations where higher accuracy is required, it may be set to 8%. Other methods for selecting the target BLER for the current BLER value are not further limited herein and may be selected by persons of ordinary skill in the art based on actual scenarios.

[0072] When NI is -130 dB, the interference is considered to be extremely small, so small that it can be ignored. Therefore, -130 dB is used as the bottom line of the NI value, and ΔNI is set to = NI - (-130).

[0073] S14: The base station determines a TPC command value according to the determined equivalent SNR and ΔBLER, and sends it to the corresponding UE, so that the UE can adjust the PUSCH uplink power.

[0074] In the prior art, there are generally two methods for determining the TPC value: cumulative and absolute. The cumulative method means that the current power adjustment value is the value of the previous power adjustment plus / minus one adjustment step indicated in the TPC. The TPC adjustment step in the cumulative method is (-1, 0, 1, 3) dB. The absolute method means that the power adjustment value indicated in the TPC is directly used. The power adjustment value indicated in the TPC is (-4, -1, 1, 4) dB. The size of the compensation value is determined by the value in the TCP command field. Different adjustment methods use different delivery methods. The cumulative method is indicated by DCI format 0 / 3, while the absolute method requires the base station to explicitly disable the cumulative method through RRC signaling.

[0075] In this step, the TPC command value may be determined based on the determined equivalent SNR and ΔBLER:

[0076] When ΔBLER < 0, it means that the current bit error rate is within the target bit error rate range. At this time, the UE power can be reduced and TPC = 0;

[0077] When ΔBLER = 0, it means that the current bit error rate is exactly equal to the target bit error rate. At this time, the UE power does not need to be adjusted and TPC = 1.

[0078] When ΔBLER>0, it means that the current bit error rate has exceeded the target bit error rate. Further judgment is made based on the equivalent SNR. When SNRequ≥threshold_SNRequ, TPC=2; when SNR equ <threshold_SNR equ When TPC=3, threshold_SNR equ The target equivalent SNR value is threshold_SNR. In the prior art, the effective working SNR value range is usually [-10, 40] dB, and it is generally believed that the channel quality is better when SNR ≥ 15 dB. Therefore, the typical target equivalent SNR value is threshold_SNR. equ It can be set to 15dB. Of course, in other embodiments, for the target equivalent SNR value threshold_SNR equ It can also be set to other values ​​according to actual conditions. The target SNR value threshold_SNR is not affected here. equ Other selection methods are further limited and can be selected by ordinary technicians in this field according to actual scenarios.

[0079] The above method shows that, for UEs within a cell, when changing the uplink closed-loop power using the TPC command value, the channel quality of the UE's transmission channel, the UE's current uplink interference level, and the BLER reported by the UE can be fully considered. Different TPC command values ​​are determined for different situations, allowing the uplink power to be adjusted. This not only reduces the total system power while meeting the link connection requirements of each UE and the base station, but also effectively saves energy.

[0080] An embodiment of the present application further provides a base station for executing the method described above.

[0081] The solution provided in the embodiment of the present application fully considers the channel status between the UE and the base station, ensures the channel status between the UE and the base station, further reduces the total system power, and effectively saves energy.

[0082] It will be appreciated by those skilled in the art that all or some of the steps, systems, and functional modules / units in the methods disclosed above may be implemented as software, firmware, hardware, and appropriate combinations thereof. In hardware implementations, the division between the functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed by several physical components in cooperation. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or temporary medium). As is well known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable, and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is well known to those skilled in the art that communication media generally embodies computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

Claims

1. A method for uplink closed-loop power control at a base station, comprising: Obtain the current channel status of the user terminal UE; Determine a transmit power control command TPC command value of the UE according to the channel state; Obtaining a PUSCH transmit power adjustment amount according to TPC information corresponding to the determined TPC command value; The channel status includes: the current SNR value and the current NI value of the transmission channel where the UE is located, and the current block error rate BLER reported by the UE; The determining a TPC command value of the UE according to the channel state includes: The equivalent SNR is determined using the following calculation expression, including: SNR equ =SNR- BLAIR / targetBLAIR* NINE; Among them, SNR equ is the equivalent SNR, BLER is the current BLER, NI is the current NI value, BLER = BLER - targetBLER, NI=NI-(-130), targetBLER is the preset target BLER; Based on the determined equivalent SNR and The BLER determines the command value of TPC.

2. The method according to claim 1, wherein The TPC command value is determined based on the determined equivalent SNR and ∆BLER as follows: when When BLER < 0, TPC = 0; when When BLER=0, TPC=1; when BLER>0, and when SNR equ ≥threshold_SNR equ When TPC=2; when BLER>0, and SNR equ <threshold_SNR equ When TPC=3; Among them, threshold_SNR equ is the target equivalent SNR value.

3. The method according to claim 2, wherein The target equivalent SNR value threshold_SNR equ is 15dB.

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