CN101895976B - A method for adjusting uplink power based on LTE-Advanced system - Google Patents

Abstract

The invention provides an uplink power adjustment method, which is applied to an LTE-Advanced system adopting a frequency spectrum polymerization technology and belongs to a resource distribution part of uplink subcarrier power. The invention mainly comprises the following steps: firstly, calculating out the TPC initial power PPUSCH, k and PPUCCH, K of PUSCH and PUCCH in accordance with an uplinkpower control formula and judging weather the TPC initial power values meet the limited conditions of maximum transmitting power; and if the result is not qualified with the conditions, carrying out the following steps: adopting a two-classification method or an N-classification method to classify the subcarriers, allocating and adjusting collective adjustment power of offset to the maximum priority and judging whether the adjusting result meets the limited power of the minimum transmitting power. The invention takes the numerical difference of the TPC initial results and the TPC former powerto reduce the power, thereby taking into account of the losses of throughput to the extent; the invention considers the minimum transmitting power values of the subcarriers, ensures transmission of PUCCH data and indirectly guarantees utilization rate of the frequency spectrum. The invention is no need of extra control signaling overhead and has simple algorithm, short arithmetic time delay and easy realization.

Description

A method for adjusting uplink power based on LTE-Advanced system

technical field

The invention is applied in the LTE-Advanced system adopting the frequency spectrum aggregation technology, and belongs to the uplink sub-carrier power resource allocation part.

Background technique

The LTE-A (Long Term Evolution-Advanced, LTE-A) system supports a minimum system bandwidth of 20MHz and a maximum bandwidth of 100MHz. Considering the existing spectrum allocation method and planning, in order to support such a large bandwidth requirement, 3GPP proposes to use spectrum aggregation (spectrum aggregation, SA) technology to solve the demand for frequency band resources. Spectrum aggregation is a technology capable of extending multiple contiguous or non-contiguous LTE carriers into transmission carriers of the LTE-A system.

The uplink power control using SA technology in the LTE-Advanced system is similar to that of Release'8, refer to "3GPP Long Term Evolution (LTE) Technology Principles and System Design", Shen Jia, ppll1-113, according to formulas (1) and (2) Calculate the power of the PUSCH and PUCCH of the subcarrier (component carrier, CC) respectively,

P _{PUSCH, k} = 10·log ₁₀ M _PUSCH (k)+P _{0_PUSCH} (k)+α(k)·PL(k)+ _ΔTF (k)+f(k)(1)

P _{PUCCH, k} =P _{0_PUCCH} (k)+PL(k)+h(·)+ _{ΔF_PUCCH} (·)+g(k)(2)

In (1), k is the label of CC, M _PUSCH is the number of resource blocks of PUSCH, P _{0_PUSCH} is a cell-specific or UE-specific parameter, α is a cell-specific path compensation coefficient, PL is a path fading loss value measured in downlink, Δ _TF is a parameter specified by the RRC layer for a specific MCS (modulation and coding scheme), and f is a function related to the cell-specific transmit power control closed-loop correction coefficient controlled by the upper layer.

In (2), P _{0_PUCCH} is a cell-specific or UE-specific parameter, PL is the path fading loss value measured in the downlink, h is a PUCCH format parameter, Δ _{F_PUCCH} is a parameter specified by the RRC layer, g is controlled by the upper layer and is specific to the cell A function related to the closed-loop correction coefficient of the transmit power control.

It can be seen from the formula that these parameters are closed-loop and open-loop power control parameters, which are jointly determined by the base station and the UE.

The UE has a fixed maximum transmit power according to the level allocated by its cell, that is, the result of power control must satisfy the formula (3):

$\underset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}{\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; CC</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}<span\; class="notranslate">\; =</span>\underset{\mathrm{<span\; class="notranslate">\; k</span>}}{\mathrm{<span\; class="notranslate">\; \&Sigma;</span>}}<span\; class="notranslate">\; \{</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; PUCCH</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; PUSCH</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; k</span>}}<span\; class="notranslate">\; \}</span><span\; class="notranslate">\; \&le;</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{\mathrm{<span\; class="notranslate">\; MAX</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

Wherein, P _MAX is the maximum transmit power of the UE.

When the SA technology is used, that is, when multiple CCs serve a UE at the same time, the CCs perform uplink transmission power control (transmission power control, TPC) calculations according to their respective power control parameters, and the initial power value obtained may not meet the maximum transmission power requirement. , power adjustment is required at this time, that is, to reduce the initial power of TPC.

Document R1-100201, "ULPC: Simultaneous transmission of PUCCH and PUSCH in case of power limitation", Motorola, January 2010, summarizes power adjustment methods into three categories: CC equivalent adjustment, CC classification adjustment and physical channel classification adjustment. The CC equivalent adjustment method means that all CCs reduce the power by the same offset. Since the characteristics of the CCs are not considered, reducing the same power for CCs with higher spectral efficiency will cause a greater throughput loss. Document R1-093395, "ULTransmission Power Control in LTE-A," Samsung, 2009, also proposes a method of power adjustment based on a certain parameter of CC, such as Modulation and Coding Scheme (MCS), which can theoretically maximize The throughput is optimized, but the complexity of the algorithm is high, the requirements on the UE are relatively high and the delay caused is relatively large. In addition, both methods do not consider the minimum transmit power of the CC.

Contents of the invention

Aiming at the problem that the initial power of the uplink TPC does not satisfy the UE restriction when the carrier aggregation technology is adopted in the LTE-Advanced system, the present invention proposes a power adjustment method that takes both performance and complexity into consideration.

The technical scheme that the present invention takes is:

A kind of uplink power adjustment method for LTE-Advanced system comprises the following steps:

Step 1, calculate the TPC initial power P _{PUCCH, k} and P _{PUSCH, k} of the PUCCH and PUSCH of the subcarrier,

P _{PUCCH, k} =P _{0_PUCCH} (k)+PL(k)+h(·)+ _{ΔF_PUCCH} (·)+g(k)

P _{PUSCH, k} = 10·log ₁₀ M _PUSCH (k)+P _{0_PUSCH} (k)+α(k)·PL(k)+ _ΔTF (k)+f(k);

为子载波k的TPC初始功率，P_MAX为UE的最大发射功率；Step 2, judge whether the initial power of the TPC satisfies the limit condition of the maximum transmission power, if so, that is Then jump directly to step 7; otherwise, enter step 3; where k is the label of the subcarrier, K is the number of subcarriers,

is the TPC initial power of subcarrier k, and P _MAX is the maximum transmission power of UE;

Step 3, determining the priority of adjustment for subcarrier classification;

Step 4, calculate the power that needs to be adjusted:

Step 5, assign the adjustment offset according to the classification result of step 3, and obtain the adjusted power

And set the priority of the adjusted subcarrier to the lowest; where Δ _k is the offset of subcarrier k, that is, CC _k , Δ _k = the power to be adjusted/M, and M is the number of subcarriers in the highest priority set ;

是否满足最小发射功率限制，若满足，即

则转至步骤7；否则，将不满足最小发射功率限制的子载波的功率设置为其最小发射功率，转至步骤4。Step 6, define the minimum transmission power ε _k , ε _k = P _{PUCCH, k} , and judge the adjusted power

Whether to meet the minimum transmit power limit, if so, that is

Then go to step 7; otherwise, set the power of the subcarriers that do not satisfy the minimum transmit power limit to their minimum transmit power, and go to step 4.

为发射功率。Step 7,

is the transmit power.

Subcarrier classification in the step 3 is divided into two types of methods and N types of methods according to classification accuracy;

The two-category method divides subcarriers into two categories according to the positive or negative value difference between the initial power of TPC and the transmit power before TPC, and selects the subcarriers with non-positive values as the priority adjustment objects;

The N-type method is classified according to the difference between the initial power of the TPC and the transmit power before the TPC, and divides the subcarriers into N levels from the negative difference to the positive difference, where N is less than or equal to the number of subcarriers, and the more the number of levels N, the classification The finer it is; the smaller the numerical difference is, the smaller the classification label is, and the higher the priority of adjustment is.

The offset adjustment method in step 5 adopts the equal offset method, that is, subcarriers of the same type are assigned the same adjusted offset.

Advantage of the present invention and positive effect are as follows:

1. The classification module of the present invention uses the numerical difference between the initial TPC result of the CC and the pre-TPC power as the CC feature, which can describe the state of the CC simply and comprehensively.

2. The present invention considers CC features, that is, the power is reduced based on the numerical difference between the initial TPC result and the power before TPC, which can take into account the loss of throughput to a certain extent.

3. The present invention considers the minimum transmission power value of the CC, ensures the transmission of PUCCH data, and indirectly ensures the spectrum utilization rate.

4. The algorithm does not require additional control signaling overhead.

5. The algorithm is simple, the operation delay is short, and it is easy to implement.

Description of drawings

Fig. 1 is a schematic flow sheet of the method of the present invention;

Fig. 2 is a comparison of the throughput between the CC equivalent adjustment method and the simplified algorithm of the present invention.

Detailed ways

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

1. Classification module

The classification module selects CCs that prioritize power adjustments. The classification standard is the numerical difference between the initial power of TPC and the transmitted power before TPC. Uplink TPC is jointly determined by cell-specific parameters or UE-specific parameters, path loss, allocated resource block size, MCS and closed-loop correction function, so this module uses TPC results to characterize CC characteristics. When the difference between the initial power of TPC and the transmit power before TPC is positive, it means that the power before TPC is not enough to support this transmission, and it is required to increase the power; otherwise, it means that the power before TPC has a margin, and the power can be reduced or maintained. The adjustment strategy of the present invention is to meet the demands of CCs for increasing power as much as possible, that is, to preferentially select CCs with power surplus for adjustment. According to the classification accuracy, it is divided into two types of methods and N types of methods.

The two-category method divides CCs into two categories according to the difference between the initial power of TPC and the transmit power before TPC, and selects CCs with non-positive values as the priority adjustment objects.

The N-type method classifies CCs into N levels from the negative difference to the positive difference according to the difference between the initial power of the TPC and the transmit power before the TPC, where N is less than or equal to the number of CCs. The more series N, the finer the classification. The smaller the numerical difference, the smaller the category label, and the higher the priority of adjustment.

2. Adjustment module

The adjustment module assigns an adjustment offset to the CCs selected by the classification module, and the goal is to reduce the initial power of the TPC by different coefficients so that the final transmission power meets the maximum transmission power limit. The adjustment algorithm adopts the equal offset method, that is, CCs of the same type are assigned the same adjustment offset.

3. Minimum Power Limiting Module

In order to ensure correct transmission of uplink control signaling, the minimum transmission power of CC _k is defined as ε _k , ε _k =P _PUCCH,k . The minimum power limitation module verifies whether the adjusted result satisfies the minimum power limitation condition, and if so, the power adjustment process is completed; otherwise, it returns to the adjustment module until the maximum and minimum transmission power limitation conditions are met at the same time.

Detailed process

The detailed process of uplink power control is as follows, and the flowchart is shown in Figure 1.

Step 1: Calculate the TPC initial power P _PUSCH,k and P PUCCH _{,k of PUSCH and PUCCH} respectively according to the uplink power control formulas (1) and (2).

为CC_k的TPC初始功率，P_MAX为UE的最大发射功率。直接跳至步骤7；否则，进入步骤3。Step 2, judging whether the initial power of the TPC satisfies the limit condition of the maximum transmission power. If satisfied, that is Where k is the label of CC, K is the number of CC,

is the TPC initial power of CC _k , and P _MAX is the maximum transmit power of the UE. Skip directly to step 7; otherwise, go to step 3.

Step 3, determine the priority of adjustment for CC classification (classification module). Select the two-category method and go to step 3.1; select the N-category method and go to step 3.2.

Step 3.1, (two-category method) compare the initial power of TPC with the transmission power before TPC, and divide the CC into two categories,

$\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; CC</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; CC</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; CC</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>\mathrm{<span\; class="notranslate">\; is</span>}\left\{\begin{array}{c}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; 0</span>}\\ <span\; class="notranslate">\; ></span>\mathrm{<span\; class="notranslate">\; 0</span>}\end{array}\right.<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; )</span>$

为TPC前CC_k的发射功率。in

is the transmit power of CC _k before TPC.

归为优先调整类别，归为次级调整类别。

Classified as a priority adjustment category, Classified as a secondary adjustment category.

Step 3.2, (N-type method) compares the TPC initial power with the transmit power before the TPC,

$\mathrm{<span\; class="notranslate">\; \&Delta;</span>}{\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; CC</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; CC</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; P</span>}}_{{\mathrm{<span\; class="notranslate">\; CC</span>}}_{\mathrm{<span\; class="notranslate">\; k</span>}}}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; t</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; i</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span><span\; class="notranslate">\; ,</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; k</span>}<span\; class="notranslate">\; \&le;</span>\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; )</span>$

确定CC_k的调整顺序，最小的

归为标号为1的集合，最大的

归为标号为N的集合。N的取值范围为[1，K]。sorted from smallest to largest

Determine the adjustment order of CC _k , the smallest

Classified as a set labeled 1, the largest

into a set labeled N. The value range of N is [1, K].

Step 4, calculate the power to be adjusted as:

Step 5. According to the classification result, assign the adjustment offset (adjustment module) to adjust the power of the set with the highest priority, and the offset allocated to each subcarrier in the set is equal: Δ _k = the power to be adjusted/M, where Δ _k is The offset of CC _k , and M is the number of CCs in the set. The adjusted power is:

At the same time, the priority of the adjusted CC _k is set to be the lowest.

Step 6, (minimum power limitation module) According to the calculation in step 1, the initial TPC power of the PUCCH of CC _k is known, and the minimum transmit power ε _k , ε _k =P _PUCCH,k is defined.

是否满足最小发射功率限制。若满足，即

则转至步骤7；否则，转至步骤6.2。Step 6.1, judge the adjustment result

Whether the minimum transmit power limit is met. If satisfied, that is

Then go to step 7; otherwise, go to step 6.2.

Step 6.2, set the power of CCs that do not meet the minimum transmit power limit to their minimum transmit power, go to step 4.

分配发射功率。Step 7, follow

Allocate transmit power.

The simulation shown in FIG. 2 is the comparison of throughput between the CC equivalent adjustment method and the simplified algorithm of the present invention. Method 1 in the figure is the CC equivalent adjustment method, that is, when the initial TPC result of the UE does not meet the maximum transmit power, all CCs are allocated equal adjustment amounts. Method 2 is a simplified algorithm of the present invention, which adopts two-category classification and equal offset adjustment. Assuming that the power before the TPC is the maximum power allowed by the UE, the power after the TPC is compared with it. Assume that the minimum power limit value of the CC is a fixed constant. The distribution of transmit power is theoretically random.

It can be seen from the figure that in the case of different CC numbers, the average throughput of method 2 is always higher than that of method 1, that is, the performance loss caused by method 1 is greater.

Claims (3)

1. A kind of uplink power adjustment method based on LTE-Advanced system, it is characterized in that comprising: Step 1, calculate the TPC initial power P _{PUCCH of subcarrier PUCCH and PUSCH, k} and P _{PUSCH, k} ; Step 2, judge whether the initial power of the TPC satisfies the limit condition of the maximum transmission power, if so, that is $\underset{k}{\mathrm{\&Sigma;}}{P}_{{\mathrm{CC}}_k}=\underset{k}{\mathrm{\&Sigma;}}\{P_{\mathrm{PUCCH},k}+P_{\mathrm{PUSCH},k}\}\&le;P_{\mathrm{MAX}},$ Then jump directly to step 7; otherwise, enter step 3; where k is the label of the subcarrier, K is the number of subcarriers,

is the TPC initial power of subcarrier k, and P _MAX is the maximum transmission power of UE; Step 3, determining the priority of adjustment for subcarrier classification; Step 4, calculate the power that needs to be adjusted:

Step 5, assign the adjustment offset according to the classification result in step 3, and obtain the adjusted power

And set the priority of the adjusted subcarrier to the lowest; where Δ _k is the offset of subcarrier k, that is, CC _k , Δ _k = the power to be adjusted/M, and M is the number of subcarriers in the highest priority set ; Step 6, define the minimum transmission power ε _k , ε _k = P _{PUCCH, k} , and judge the adjusted power Whether to meet the minimum transmit power limit, if so, that is

Then go to step 7; otherwise, set the power of the subcarriers that do not satisfy the minimum transmit power limit to their minimum transmit power, and go to step 4. Step 7,

is the transmitting power; The subcarrier classification described in step 3 is divided into two types of methods and N types of methods according to classification accuracy; The two-category method divides subcarriers into two categories according to the positive or negative value difference between the initial power of TPC and the transmit power before TPC, and selects the subcarriers with non-positive values as the priority adjustment objects; The N-type method is classified according to the difference between the initial power of the TPC and the transmit power before the TPC, and the sub-carriers are divided into N levels from negative difference to positive difference, where N is less than or equal to the number of sub-carriers, and the more the number of levels N, the classification The finer it is; the smaller the numerical difference is, the smaller the classification label is, and the higher the priority of adjustment is. 2. according to the described a kind of uplink power adjustment method based on LTE-Advanced system of claim 1, it is characterized in that: the TPC initial power of the PUCCH of subcarrier and PUSCH in step 1 calculates according to following formula: P _{PUCCH, k} =P _{0_PUCCH} (k)+PL(k)+h(·)+ _{ΔF_PUCCH} (·)+g(k) P _{PUSCH, k} = 10·log ₁₀ M _PUSCH (k)+P _{0_PUSCH} (k)+α(k)·PL(k)+ _ΔTF (k)+f(k) Among them, k is the label of the subcarrier, M _PUSCH is the number of resource blocks of PUSCH, P _{0_PUSCH} is a cell-specific or UE-specific parameter, α is a cell-specific path compensation coefficient, PL is the path fading loss value of downlink measurement, Δ _TF is a parameter specified by the RRC layer for a specific modulation and coding method, f is a function related to the cell-specific transmit power control closed-loop correction coefficient controlled by the upper layer, h is a PUCCH format parameter, Δ _{F_PUCCH} is a parameter specified by the RRC layer, g is a function related to cell-specific transmit power control closed-loop correction coefficients controlled by higher layers. 3. A kind of uplink power adjustment method based on LTE-Advanced system according to claim 1, it is characterized in that: the adjustment method of the offset described in step 5 adopts the equal offset method, that is, the subcarriers of the same category are allocated the same The adjustment offset.

Images