CN1728582A - Method for tracking and correcting error of indication of channel quality in WCDMA system - Google Patents

Abstract

The invention discloses a method for tracking and correcting channel quality indication in a WCDMA system. When the CQI value of the HS-PDSCH channel reported by the UE to the base station cannot truly reflect the actual quality of the HS-PDSCH channel, the method estimates the HS-PDSCH channel quality of the base station. The block error rate of the downlink transmission signal of the PDSCH channel, and according to the relationship between the estimated block error rate and the real block error rate, it is judged whether the CQI value reported by the UE can truly reflect the quality of the HS-PDSCH channel. When it is judged that there is a deviation between the CQI value reported by the UE and the CQI value that actually reflects the channel quality of the HS-PDSCH, the downlink transmission power of the base station or the CQI value reported by the UE is gradually tracked and adjusted to make the CQI value reported by the UE consistent with the HS-PDSCH channel quality. - The actual quality of the PDSCH channel is consistent, so that the base station can reasonably allocate system resources and improve system performance.

Description

A Tracking and Correcting Method of Channel Quality Indication in WCDMA System

technical field

The invention relates to a channel transmission technology of a wideband code division multiple access WCDMA system, in particular to a tracking and correction method for channel quality indication in the WCDMA system.

Background technique

High-speed downlink data packet access HSDPA is a modulation and demodulation algorithm proposed by 3GPP in the R5 protocol to meet the asymmetrical requirements of uplink and downlink data services. It can be used without changing the existing WCDMA network structure. Increase the downlink data service rate to 10Mbps. This technology is an important technology for improving downlink capacity and data service rate in the later stage of WCDMA network construction.

In the HSDPA algorithm, the user UE feeds back the channel quality indication CQI of the high-speed downlink shared channel HS-DSCH in the uplink high-speed dedicated physical control channel HS-DPCCH. By analyzing the CQI values reported by all UEs, the base station can know each UE The channel quality situation of the channel, so as to determine the allocation of shared resources in each UE. The definition of CQI in the protocol 3GPP is as follows: within the unrestricted observation time, the UE reports the highest CQI value to the base station. A single HS-PDSCH subframe received within the reference time is formed according to the transport block size, HS-PDSCH code number and modulation mode corresponding to the CQI value or a lower CQI value, and the block error rate BLER does not exceed 0.1. It can be known from the above definition that each CQI value corresponds to a certain transport block size, HS-PDSCH code number, and modulation mode. The base station selects the transport block size, coding mode, and modulation of the transmitted data according to the CQI value reported by the UE. way, through the combined use of the three to improve the use efficiency of the entire community.

In order to obtain the correct CQI value, generally speaking, the UE first estimates the SNR of the HS-PDSCH channel, and then according to the SNR level of the HS-PDSCH channel, according to the SNR of the HS-PDSCH received signal and the channel quality indicator CQI value curve to get the corresponding CQI value. The signal-to-noise ratio of the HS-PDSCH channel is obtained in the following manner, assuming that the formula for calculating the total received power of the HS-PDSCH channel is: P _HSPDSCH =P _CPICH +Γ+ΔdB, wherein P _HSPDSCH is the signal of the HS-PDSCH channel Total received power; P _CPICH is the received power of the common pilot channel CPICH measured by the UE; Γ is the measured power offset of the HS-PDSCH downlink transmission power configured by the upper layer RNC relative to the common pilot channel CPICH received power; Δ is the reference The amount of power adjustment depends on the class classification of the UE and the channel quality CQI reported at that time. Its value is generally 0. When the channel quality is so good that the amount of data reaches the UE class limit, Δ will become a negative value. To reduce the transmit power on HS-PDSCHs. For details, refer to Chapter 6A.2 of the standard protocol 3GPP TS 25.433 V5.8.0 (2004-03). From the above formula, it can be seen that there is a certain proportional relationship between the transmission power value of the HS-PDSCH channel and the CPICH channel. Since the path losses they pass through to reach the UE are the same, it can be considered that the SNR of the HS-PDSCH channel on the UE side is the same as that of the CPICH channel. There is also a certain proportional relationship between the signal-to-noise ratio. Therefore, the UE measures the signal-to-noise ratio SNR of the CPICH channel by measuring the power offset Γ configured by _{the CPICH} ^UE and the RNC, and then according to the formula ${\mathrm{SNR}}_{\mathrm{HSPDSCh}}^{\mathrm{UE}}={\mathrm{SNR}}_{\mathrm{CPICH}}^{\mathrm{UE}}+\mathrm{\Γ}$ Calculate the signal-to-noise ratio SNR _HSPDSCH ^UE of the received signal of the HS-PDSCH channel, and then obtain the CQI value of the HS-PDSCH channel.

In the prior art, first, the RNC configures the measurement power offset Γ to the base station and the UE respectively; secondly, the UE obtains the measured signal-to-noise ratio SNR of the CPICH channel according to the measurement power offset Γ configured by _{the CPICH} ^UE and the RNC, through the formula ${\mathrm{SNR}}_{\mathrm{HSPDSCh}}^{\mathrm{UE}}={\mathrm{SNR}}_{\mathrm{CPICH}}^{\mathrm{UE}}+\mathrm{\Γ}$ Calculate the signal-to-noise ratio SNR _HSPDSCH ^UE of the received signal on the HS-PDSCH channel, and then obtain the corresponding CQI value through the curve of SNR and CQI value, and report it to the base station; again, the base station configures the CPICH channel according to the upper layer RNC The transmission power value and Measure the power offset Γ, and calculate the downlink transmission power value of the HS-PDSCH channel through the formula P _HSPDSCH =P _CPICH +Γ+ΔdB; finally, the base station selects the data transmission format according to the CQI value reported by the UE, including the size of the data block, The number of transmitted code channels and modulation mode, and then data transmission.

It can be seen from the above process that the base station allocates power and transmits data according to the CQI value reported by the UE. When the CQI value reported by the UE is equal to the real CQI value, the base station will configure resources reasonably, which helps to improve system performance. However, on the one hand, due to the difference in the demodulation performance of each UE on the HS-PDSCH channel, there is often a certain gap between the CQI value reported by the UE and the CQI value reflecting the real situation of the HS-PDSCH channel. On the other hand, because the protocol stipulates that the upper layer RNC may sometimes not configure the measurement power offset Γ on the base station side, the base station cannot obtain the real CQI value. In the above two cases, when the base station cannot obtain the real CQI value, it cannot be correctly evaluated. The channel condition of the UE affects the allocation of resources by the base station, which eventually leads to the deterioration of HSDPA performance.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a method for tracking and correcting channel quality indication in a WCDMA system. By this method, when there is a deviation between the CQI value reported by the UE and the real CQI value, the deviation is eliminated and the real CQI value is obtained. The problem of the CQI value.

In order to achieve the above object, the technical solution of the present invention mainly includes the following steps:

a. The user UE obtains the high-speed downlink shared channel HS by calculating the sum of the SNR of the CPICH and the measurement power offset according to the measured SNR of the common pilot channel CPICH and the measurement power offset configured by the RNC - The signal-to-noise ratio of the PDSCH received signal, and then obtain the corresponding CQI value through the curve of the signal-to-noise ratio of the HS-PDSCH received signal and the CQI value of the channel quality indicator, and report it to the base station;

b. The base station obtains the downlink transmission power of the HS-PDSCH by calculating the sum of the transmission power of the CPICH, the measurement power offset and the reference power adjustment amount according to the transmission power of the CPICH configured by the measurement power offset and the upper layer RNC;

c. The base station selects the transport block size, HS-PDSCH code number, and modulation mode for sending data according to the obtained CQI value, and sends data to the UE through the HS-PDSCH;

It is characterized in that the method further includes:

d. After receiving the data sent by the base station, the UE decodes the data. If the decoding is successful, it sends a correct reception response message to the base station, otherwise it sends an error reception response message;

e. The base station estimates the block error rate of the data received by the UE through the HS-PDSCH according to the received correct reception response message and the wrong reception response message, and sets a reference value reflecting the real block error rate of the HS-PDSCH,

If the estimated block error rate is greater than the reference value, the base station increases the downlink transmit power of HS-PDSCH according to the set step value; or the base station keeps the downlink transmit power unchanged, and reduces the UE report CQI value;

If the estimated block error rate is less than the reference value, the base station reduces the downlink transmit power of HS-PDSCH according to the set step value; or the base station keeps the downlink transmit power unchanged, and increases the downlink transmit power reported by the UE according to the set step value CQI value.

In the above method, the base station side measurement power offset in step b is configured by the upper layer RNC, and when the RNC does not configure the measurement power offset on the base station side, then arbitrarily designate a value as the base station side measurement power offset value.

Preferably, the specified base station side measurement power offset value is 0.

In the above method, the method for estimating the block error rate of the UE receiving data through the HS-PDSCH in the step e is: the sum of the correct reception response message and the wrong reception response message received by the base station is a certain set threshold, Then calculate the ratio of the erroneously received acknowledgment message to the set threshold, and use the ratio as the estimated value of the block error rate.

Preferably, in the step e, the reference value reflecting the true block error rate of the HS-PDSCH is set to 0.1.

In the above method, the step e further includes sending data according to the transport block size, HS-PDSCH code number and modulation mode corresponding to the current CQI value.

In summary, when the CQI value of the HS-PDSCH channel reported by the UE to the base station cannot truly reflect the actual quality of the HS-PDSCH channel, the present invention estimates the block error rate of the downlink transmission signal of the HS-PDSCH channel of the base station, and judges Estimate the relationship between the block error rate and 0.1 to judge whether the CQI value reported by the UE can truly reflect the quality of the HS-PDSCH channel. When there is a deviation, the downlink transmission power of the base station or the CQI value reported by the UE is gradually tracked and adjusted to make the CQI value reported by the UE consistent with the actual quality of the HS-PDSCH channel, so that the base station can reasonably allocate system resources and improve system performance. .

Description of drawings

Fig. 1 is the method flow chart of embodiment 1 of the present invention;

Fig. 2 is a flow chart of the method in Embodiment 2 of the present invention.

Detailed ways

In order to make the object, 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.

Embodiment one

The technical solution of this embodiment is a method for the base station to track and correct the CQI value reported by the UE by adjusting the measurement power offset value Γ on its side, as shown in FIG. 1 , specifically including the following steps: In step 101, the UE The measured signal-to-noise ratio SNR of the CPICH channel obtained by the measurement _CPICH ^UE and the RNC configured measurement power offset Γ, by the formula ${\mathrm{SNR}}_{\mathrm{HSPDSCh}}^{\mathrm{UE}}={\mathrm{SNR}}_{\mathrm{CPICH}}^{\mathrm{UE}}+\mathrm{\Γ}$ Calculate the signal-to-noise ratio SNR _HSPDSCH ^UE of the received signal on the HS-PDSCH channel, and then obtain the corresponding CQI value through the curve of SNR and CQI value, and report it to the base station.

In step 102, it is judged whether the RNC has configured the measurement power offset Γ on the base station side, if yes, then directly execute step 103, otherwise the base station arbitrarily specifies a value for the measurement power offset Γ, such as Γ=0, and then executes step 103.

In step 103, the base station calculates the downlink transmission power value of the HS-PDSCH channel according to the obtained measured power offset Γ and the transmission power value of the CPICH channel configured by the upper layer RNC through the formula P _HSPDSCH =P _CPICH +Γ+ΔdB.

In step 104, the base station selects the transport block size, HS-PDSCH code number and modulation mode for sending data according to the CQI value reported by the UE, and sends data to the UE through the HS-PDSCH channel.

In step 105, after receiving the data sent by the base station, the UE decodes the data, and if the decoding is successful, sends an acknowledgment (ACK) message to the base station, or sends an acknowledgment (NACK) message to the base station.

In step 106, the base station estimates the block error rate BLER of the UE receiving data through the HS-PDSCH channel according to the received ACK and NACK messages. The estimation method is: when the total number of received ACK and NACK reaches the set threshold N, such as When 100, calculate NACK/(NACK+ACK), if the calculated result is equal to the set reference value reflecting the real block error rate of HS-PDSCH, such as 0.1, it means that the CQI value reported by the UE is equal to the real CQT value; if If it is greater than 0.1, execute step 107; if it is less than 0.1, execute step 108.

In step 107, the base station increases the downlink transmit power value of the HS-PDSCH channel by 1 dB, ie P _PDSCH +1, according to the set step step1, and then executes step 104.

In step 108, the base station reduces the downlink transmission power value of the HS-PDSCH channel according to the set step step1, and then executes step 104.

Embodiment two

The technical solution of this embodiment is a method for the base station to track and correct the CQI value reported by the UE by adjusting the CQI value reported by the UE, as shown in FIG. 2 , specifically including the following steps:

In step 201, the UE obtains the measured signal-to-noise ratio SNR of the CPICH channel based on the measurement power offset Γ configured by _{the CPICH} ^UE and the RNC, through the formula ${\mathrm{SNR}}_{\mathrm{HSPDSCh}}^{\mathrm{UE}}={\mathrm{SNR}}_{\mathrm{CPICH}}^{\mathrm{UE}}+\mathrm{\Γ}$ Calculate the signal-to-noise ratio SNR _HSPDSCH ^UE of the received signal on the HS-PDSCH channel, and then obtain the corresponding CQI value through the curve of SNR and CQI value, and report it to the base station.

In step 202, it is judged whether the RNC has configured the measurement power offset Γ on the base station side, if yes, then directly execute step 203, otherwise the base station arbitrarily specifies a value for the measurement power offset Γ, such as Γ=0, and then executes step 203.

In step 203, the base station calculates the downlink transmit power value of the HS-PDSCH channel according to the obtained measured power offset Γ and the transmit power value of the CPICH channel configured by the upper RNC through the formula P _HSPDSCH =P _CPICH +Γ+ΔdB.

In step 204, the base station selects the transport block size, HS-PDSCH code number and modulation mode for sending data according to the obtained CQI value, and sends data to the UE through the HS-PDSCH channel.

In step 205, after receiving the data sent by the base station, the UE decodes the data, and if the decoding is successful, sends an acknowledgment (ACK) message to the base station, or sends an acknowledgment (NACK) message to the base station.

In step 206, the base station estimates the block error rate BLER of the data received by the UE through the HS-PDSCH channel according to the received ACK and NACK messages. The estimation method is: when the total number of received ACKs and NACKs reaches the set threshold N, such as When 100, calculate NACK/(NACK+ACK). If the calculation result is equal to the set reference value reflecting the real block error rate of HS-PDSCH, such as 0.1, it means that the CQI value reported by the UE is equal to the real CQI value; if it is greater than 0.1 , execute step 205; if less than 0.1, execute step 206.

In step 207, the base station decreases the CQI value reported by the UE according to the set step step2, and then executes step 204.

In step 208, the base station increases the CQI value reported by the UE according to the set step step2, and then executes step 204.

In a word, the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention.

Claims (7)

1, the tracking method for correcting error of channel quality indication in a kind of WCDMA system comprises the steps:

A, user UE are according to the signal to noise ratio of the Common Pilot Channel CPICH that measures and the measurement power bias of RNC configuration, signal to noise ratio by calculating described CPICH with measure the signal to noise ratio that the power bias sum obtains high-speed downlink shared channel HS-PDSCH received signal, and then obtain corresponding C QI value, and report the base station by the signal to noise ratio of HS-PDSCH received signal and the curve of channel quality indicator (CQI) value;

B, base station be according to the transmitting power of the CPICH that measures power bias and upper strata RNC configuration, the transmitting power by calculating described CPICH, measures the down transmitting power that power bias and reference power adjustment amount three sum obtain HS-PDSCH;

Transmission block size, HS-PDSCH yardage and the modulation system of data selected to send according to the CQI value that obtains in c, base station, sends data by HS-PDSCH to UE;

It is characterized in that this method further comprises:

D, UE decode to data after receiving the data of base station transmission, if decode successfully, then send the correct response message that receives to the base station, receive response message otherwise send mistake;

The Block Error Rate of UE by HS-PDSCH reception data estimated according to correct reception response message that receives and the wrong response message that receives in e, base station, and sets the reference value of a true Block Error Rate of reflection HS-PDSCH,

If the Block Error Rate of estimating gained is greater than this reference value, then the down transmitting power of HS-PDSCH is improved in the base station according to the step value of setting; Perhaps the base station keeps down transmitting power constant, reduces the CQI value that UE reports according to the step value of setting;

If the Block Error Rate of estimating gained is less than this reference value, then the base station reduces the down transmitting power of HS-PDSCH according to the step value of setting; Perhaps the base station keeps down transmitting power constant, increases the CQI value that UE reports according to the step value of setting.

2, the tracking method for correcting error of channel quality indication according to claim 1 is characterized in that: base station side measurement power bias is disposed by upper strata RNC among the described step b.

3, the tracking method for correcting error of channel quality according to claim 1 indication is characterized in that: in described step b, as RNC during not at base station side allocating and measuring power bias, then specify a value to measure power bias value as base station side arbitrarily.

4, the tracking method for correcting error of channel quality indication according to claim 3, it is characterized in that: it is 0 that the base station side of appointment is measured power bias value.

5, the tracking method for correcting error of channel quality indication according to claim 1, it is characterized in that: estimate among the described step e that UE comprises by the step that HS-PDSCH receives the Block Error Rate of data: when the correct reception response message that receives when the base station reaches a certain preset threshold with wrong reception response message sum, mistake in computation receives the ratio of response message and this preset threshold, and with the estimated value of ratio as described Block Error Rate.

6, the tracking method for correcting error of channel quality indication according to claim 1 is characterized in that: the reference value of setting the true Block Error Rate of reflection HS-PDSCH among the described step e is 0.1.

7, the tracking method for correcting error of channel quality indication according to claim 1 is characterized in that: described step e further comprises, according to sending data with the corresponding transmission block size of current C QI value, HS-PDSCH yardage and modulation system.

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