KR20070067196A - Outer loop power control of user equipment in wireless communication - Google Patents

Abstract

A faster power control method especially of use in case of a UE device communicating with a SAP (e.g. a Node B) of a UTRAN via E-DCH, where instead of the SAP (e.g. a Node B) receiving from the serving RNC a new SIR target to use because of changing channel conditions in what is called outer loop power control, the SAP instead receives a BLER target or a target value for some other indicator of channel quality (such as a new-data indicator value of EUPA) to use as a guide for determining, by itself, an appropriate SIR target.

Description

Outer loop power control of user equipment in wireless communication

This application is part of an ongoing application of US Patent Application No. 10 / 965,236, filed October 13, 2004, the priority of which is claimed in accordance with all supporting text of section 35 of the United States Federal Law, including 120, 121, and 365 (c). The text of the evidence is not limited to this.

The present invention relates to the wireless transmission of data and voice, for example through a third generation cellular communication network. In particular, the present invention relates to adjusting the power level of a transmitter of a user terminal device, such as a cellular handset.

The signal power output level of a user terminal (UE) device (e.g. cellular handset) communication over a cellular communication network is received from a service access point (SAP) of the network (e.g., a base station (node B or BTS)). Controlled by command. Effective means of the power control method require minimizing propagation disturbances between user terminal devices sharing a common frequency band. Ideally, all signals in the uplink direction should arrive at the receiver of the service access point with the same signal strength. Thus, the output power level of the user terminal device is constantly adjusted. Devices that are far from the service access point must transmit at significantly higher power than devices that are close to the service access point.

There are two basic ways of power control: open loop and closed loop. In open loop power control, the user terminal device sets its output power to a value selected by the user; Open loop power control is used to set initial uplink and downlink transmit power when the user terminal device connects to the network. In closed loop power control, the service access point measures the quality of transmission from the user terminal device and then adjusts the transmission power used by the user terminal device, thus adjusting the quality of transmission from the user terminal device to the user terminal device. Send a power control command.

Third generation (3G) cellular system including so-called UTRAN (UMTS Terrestrial Radio Access Network), which in turn includes a service access point for communication using a user terminal device Universal Mobile Telecommunication System (UMTS) In a communication system, uplink closed loop power control includes inner loop power control (ILPC) and outer loop power control (OLPC). Previously, the user terminal transmitter may be responsible for one or more transmit power control commands received from a service access point to maintain an uplink signal-to-interference ratio (SIR) at a given target signal-interference ratio. The uplink signal-interference ratio is measured by the service access point. The UTRAN typically includes one or more service access points that are all under the control of a Radio Network Controller (RNC) for each cell site and the wireless network controller (finally public In the outer loop power control, the wireless network controller adjusts the target signal-interference ratio according to the uplink channel quality, and the wireless network controller accesses the uplink channel quality to the service. The decision is made based on the information provided by the point. In general, the target signal-to-interference ratio is independently updated for each user terminal device according to the BLOCK (BLock Error Rate) value, the BER (Bit Error Rate) value, or any other indication of channel quality. do.

In the outer loop power control of UTRAN-FDD (Frequency Division Duplex) in uplink (UL) dedicated channel (DCH), the radio controller controls the service access point for each uplink channel. It is known in the art to update the stored target signal-interference ratio. The service access point compares the target signal-interference ratio with the signal-interference ratio for the uplink signal and commands a power control command to the user terminal device to keep the received signal-interference ratio as close as possible to the target signal-interference ratio. Send out to manage external loop power control. This outer loop power control mechanism relies on the radio network controller to adjust the target signal-interference ratio based on block error rate statistics of the received estimated connection quality. Such outer loop power control is a relatively slow control mechanism. 1 illustrates a prior art of uplink power control for a connection through a dedicated channel between a user terminal device 10 and a service access point 11 and the wireless network controller 12 controlling the service access point is measured. The target signal-interference ratio is updated for the uplink dedicated channel according to the block error rate or other indicator of the quality of the channel. The service access point then activates closed loop power control and attempts to keep the received signal as close as possible to the target signal-interference ratio.

The current challenge in the so-called 3G Partnership Project (3GPP), which describes UMTS in detail, is to detail the enhanced dedicated channel (E-DCH) support. The enhanced dedicated channel is intended to provide improved uplink packet access in UTRAN-FDD using a dedicated transport channel, which requires a more efficient outer loop power control mechanism. This is because the data rate of the uplinked dedicated channel connection changes frequently and within a very large dynamic range. As a result, current outer-loop power control used with existing dedicated channels will not always operate as efficiently as enhanced dedicated channels.

In one point, the uplink outer loop power control of the prior art is also performed in the wireless network controller because the uplink may belong to soft handover and only the wireless network controller has information on the multiple links of the handover user terminal. Notable However, there is a long transmission delay between the radio network control and the service access point, typically hundreds of milliseconds. This long delay thus hinders out-of-loop power control using real-time information such as fading information and also hybrid automatic repeat request (HARQ) information (i.e. whether there was a packet error indicating that higher power is needed). do. Thus, in some applications it is desirable to be able to use hybrid automatic retransmission request information for outer loop power control.

Since outer loop power control can directly affect overall system capability, performance, and coverage, it is desirable to have a fast and efficient outer loop power control scheme for enhanced dedicated channels.

As a first embodiment of the present invention, one method is provided, and the method

The target value for the indicator of the channel quality is compared with the measured value for the indicator of the channel quality so that the service access point (SAP) of the radio access network (RAN) corresponds to the new target signal-interference corresponding to the indicator of the channel quality. Determining a ratio (SIR); And

The service access point using the target signal-interference ratio to provide a power control command to a user terminal device that supplies an uplink signal.

According to the first aspect of the present invention, the indication of the channel quality may be a block error rate (BLER), in particular a block error rate measured before any hybrid automatic retransmission request process.

In addition, according to the first aspect of the present invention, the indicator of channel quality may be a block error rate measured after a hybrid automatic retransmission request process using a new indicator of data indicating whether transmission includes retransmission.

Also in accordance with the first aspect of the invention the service access point may use a plurality of target signal-interference ratios, each corresponding to a different data rate, the method wherein the service access point senses the data rate and the sensing The method may further include selecting a target signal-interference ratio from the plurality of target signal-interference ratios based on the data rate. Moreover, the method also adjusts one or more of the target signal-interference ratios of the plurality of target signal-interference ratios based on comparing the target indicator of the channel quality with the measurement for the indicator of the channel quality. It may further comprise a step.

In addition, according to the first aspect of the present invention, the wireless access network may include a radio network controller (RNC) for connecting the service access point to a core network of a telecommunication system, wherein the wireless network controller is a target of the channel quality. Indicators can be provided.

A second aspect of the invention provides a computer program product, the computer program product comprising a computer readable storage structure for executing computer program instructions, the computer processing of which performs the steps of the method. You can do this step

The service access point (SAP) of the radio access network (RAN) compares the target value for the indicator of the channel quality with the measured value for the indicator of the channel quality and compares the new target signal-interference ratio according to the indicator of the channel quality. Determining SIR); And

And using the target signal-interference ratio to provide a power control command to a user terminal device that provides the uplink signal to the service access point.

A third aspect of the invention is provided with a service access point (SAP) of a radio access network (RAN), the service access point,

Means for determining a new target signal-interference ratio (SIR) in accordance with the indication of channel quality by comparing the target value for the indication of channel quality with the service access point a measurement value for the indication of channel quality; And

Means for using the target signal-interference ratio to provide a power control command to a user terminal device to which the service access point supplies an uplink signal.

A fourth aspect of the invention is provided with a system, the system comprising:

A user terminal (UE) device for responding to a power control command and for providing an unlink signal; And

A system comprising: a wireless access network (RAN) for connecting the user terminal device to a core network.

The wireless access network

A service access point (SAP) in response to the uplink signal and for providing the power control command; And

And a wireless network controller for providing an indication of a target block error rate (BLER) or other channel quality.

The service access point is

Means for determining, by the service access point, a target signal-interference ratio (SIR) in accordance with an indicator of channel quality by comparing a target value for an indicator of channel quality with a measurement for the indicator of channel quality; And

The service access point compares the measured signal-interference ratio value with a target signal-interference ratio to obtain a measured signal-interference ratio value for the uplink signal and provides the power control command to the user terminal device; Means for using the target signal-interference ratio.

The above and further objects, features and advantages of the present invention will become apparent from consideration of the following detailed description of the invention provided in connection with the accompanying drawings.

1 is a block diagram / flow diagram illustrating a system in which uplink power control is performed for an uplink dedicated channel connecting a user terminal device and a service access point according to the prior art.

2A is a block diagram of initial setup and subsequent closed loop power control in accordance with one embodiment of the present invention in which a block error rate is determined prior to hybrid automatic retransmission request processing.

2B is a block diagram of initial setup and subsequent closed loop power control in accordance with one embodiment of the present invention in which a block error rate is determined after hybrid automatic retransmission request processing.

3 is a schematic timing diagram for enhanced uplink packet access (EUPA) in the case of an embodiment of the present invention in which the block error rate is determined after hybrid automatic retransmission request processing.

The present invention is described below for the case where a user terminal device communicates with a service access point via an enhanced dedicated channel communication channel. However, the present invention is in no way limited to using an enhanced dedicated channel and for communication in a particular system comprising a user terminal device receiving a power control command from a service access point for a wireless communication having a service access point. Replace use.

Referring to FIG. 2A, according to the present invention, the service access point is the user terminal device in establishing a connection from the user terminal device 10 to the service access point 21 under the control of the radio network controller 22 of the UTRAN. Receive an uplink signal having a specific signal-interference ratio (SIR) and a data rate R. In accordance with the present invention, the target signal-interference ratio coordination module 21a of the service access point is described below by a channel such as a block error rate (or a new data indication index as described below if possible) from the radio network controller 22. Receive a target value for an indicator of quality and determine a new target signal-interference ratio according to the target indicator of channel quality (e.g., block error rate). By selecting a target block error rate as an example of the target indication indicator of channel quality, the service access point compares the target block error rate with the measured uplink block error rate to determine a new signal-interference ratio. In the embodiment shown in FIG. 2A, the uplink block error rate is measured by the measurement unit (MU) 21b before any hybrid automatic retransmission request operation 21c. (Outer loop power control and estimated block error rate are continuous. It's a process.

Referring to FIG. 2B, in another embodiment of the present invention, the block error rate is measured by the measuring device 21b 'because it is executed after the hybrid automatic retransmission request process, and in fact, hybrid automatic retransmission for determining the block error rate value. Use the information provided by the required process. In either embodiment shown in FIG. 2A or FIG. 2B, the measuring device does not necessarily measure the block error rate directly from the link signal but instead blocks from any result of the link signal processing that can be obtained including the decoding result. Estimate the error rate value. Thus in the embodiment of FIG. 2B the measuring device is actually made available by the hybrid automatic retransmission request process and uses the new data indicators described in more detail below; The hybrid automatic retransmission request process decodes at least the components of the link signal to provide new data indicators that can be used to estimate the block error rate.

Thus, in some embodiments (FIG. 2A), the measurement device 21b that provides a block error rate value is located before every hybrid automatic retransmission request process, while in other embodiments (FIG. 2B) the measurement that provides a block error rate value. The device 21b 'uses the information from the hybrid automatic retransmission request process and thus is located after such hybrid automatic retransmission request process.

Also, in any of the two embodiments (FIGS. 2A and 2B), rather than receiving a new target signal-interference ratio from the radio network controller as performed in accordance with a conventional outer loop power control procedure. The service access point adjusts the target signal-interference ratio by comparing the measured block error rate value used for the outer loop power control with the target block error rate value. The adjustment made to the target signal-interference ratio by the service access point according to the invention is based on the difference between the block error rate and the measured uplink block error rate value; If the block error rate value is less than the target block error rate, the target signal-interference ratio is reduced. The service access point uses a new signal-interference ratio to provide power control commands to the user terminal device. (The block error rate value measured before or after the hybrid automatic retransmission request process is determined from a channel condition and the service access point. Consider both the distance to the user terminal device.)

In the case of an enhanced dedicated channel, the data rate may change rapidly and the present invention further provides the use of different target signal-interference ratios for each of several data rates if the service access point is feasible. The interference ratio corresponds to the same target block error rate. In such an embodiment, the service access point determines a target signal-interference ratio to use for power control based on the measured value of the uplink data rate. Figure 2 illustrates this embodiment, wherein the service access point uses a table 21d of data rates for the target signal-interference ratio value. The service access point senses the data rate and selects a new target signal-interference ratio corresponding to the sensed data rate if possible from one of the tables 21d if the data rate changes.

When using the table to provide target signal-interference ratios for different data rates, the service access point also sets other data rates when tuning the target signal-interference ratio for the data rate being used by the user terminal device. It may or may not tune the target signal-interference ratios. It is reasonable to change the target signal-interference ratios not only for the data rate in use but also for other data rates because the target signal-interference ratio for the data rate in use is tuned because the channel conditions change (deteriorated or improved). This is because the channel conditions are somewhat independent of the data rate. However, for some data rates, especially low data rates, the initial value or starting value of the target signal-interference ratio should be used as the starting point or final tuned value for tuning.

The service access point may use different target block error rate values even at different times or for different data rates or different services. Means other than the wireless network controller may be provided with one or the other of the target block error rate values. For example, the O & M may provide one or the other of the target block error rates to be used by the service access point.

In the embodiment of the present invention shown in FIG. 2B, hybrid automatic retransmission request information in the case of enhanced uplink packet access (of Wideband Code Division Multiple Access (WCDMA)) of UMTS is an indicator of channel quality. Particular preference is given to essentially being used as; More specifically, the measured block error rate value is determined using the hybrid automatic retransmission request information. A synchronous hybrid automatic retransmission request is used in enhanced uplink packet access in wideband code division multiple access. Hybrid when the terminal receives negative response characters for the most recent previous transmission from the base stations in the terminal's active device for an enhanced uplink packet access link having M SAW (Stop-And-Wait) channels Retransmission of the automatic retransmission request is sent in M-1 TTIs (transmission time intervals) after the most recent previous transmission. In accordance with the present invention, the service access point uses a new data indicator that is carried on an enhanced uplink packet connection of an E-PDCCH (Enhanced Dedicated Physical Control Channel) to determine the measured block error rate value, which is again used. It is a measured value of the display index of the channel quality. As in the embodiment of FIG. 2A, the measured block error rate and target block error rate are compared to determine how to adjust the target signal-interference ratio used for outer loop power control.

 In using the new data indicator, decoding of all the service access points (base stations in UMTS) should be used in a soft handover (SHO) active device of a user terminal device (mobile station). Each service access point detects whether a new data block or a retransmission data block has been delivered at the i + M th TTI to decode the i th TTI at all service access points in the soft handover activation device of the user terminal. Able to know. The retransmitted data block detected by the service access point in the i + M th TTI represents all service access points that were not correctly received in the i th TTI. As described above, information indicating whether a new data block or a retransmission data block is delivered in the i + M th TTI is embedded in a new data indication indicator of an enhanced pysical dedicated control channel (E-PDCCH). According to the present invention, the block error rate of the j-th hybrid automatic retransmission request transmission is updated by detecting a new data indicator for the i + Mth TTI, and the j-th hybrid automatic retransmission request transmission of the packet is received at the i-th TTI. . Thus, the target signal-interference ratio is adjusted based on the block error rate of other hybrid automatic retransmission request transmissions, i.e., the new data indicator.

3, an example is shown for M = 3 (that is, three SAW channels) in which outer-loop power control operates according to N (new data) or R (retransmission) in the E-PDCCH. At the first TTI 31 (0-10 ms), P1 in DB1 is delivered with a new data indicator (in E-PDCCH) indicating new data (as opposed to retransmission). Both base station 1 and / or base station 2 respond with a negative response character 32 and the negative response character is not received until the third TTI 33. DB1 is then retransmitted at the fourth TTI 34. In accordance with the present invention, the new data indicator in the fourth TTI 34 is used to estimate a block error rate that can be compared with a target value and is used for the outer loop power control depending on the comparison. Tune the rain.

The present invention can simplify the performance of the enhanced uplink packet access base station and the radio network controller, i.e. eliminates the need for outer loop power control signal processing between the base station and the radio network controller.

In fact, the false positive / negative character feedback error is neglected in the method according to the present invention because the error rate of the positive / negative character is very low and is generally 1% for the positive character and 0.1% for the negative character. Has a detrimental effect.

It is to be understood that the above-described arrangements merely illustrate the application of the nature of the present invention. Numerous modifications and alternative arrangements of the invention will be made by those skilled in the art not far from the scope of the invention and the appended claims are intended to protect such modifications and arrangements.

The present invention can simplify the performance of the enhanced uplink packet access base station and the radio network controller, i.e. eliminates the need for outer loop power control signal processing between the base station and the radio network controller.

Claims (20)

The target value for the indicator of channel quality is compared with the measured value for the indicator of channel quality so that the service access point (SAP) of the radio access network (RAN) corresponds to the new target signal-interference corresponding to the indicator of the channel quality. Determining a ratio (SIR); And And the service access point using the target signal-interference ratio to provide a power control command to a user terminal device that supplies an uplink signal. The method of claim 1, The indicator of channel quality is a block error rate (BLER) measured prior to any hybrid automatic retransmission request process. The method of claim 1, The indicator of channel quality is measured after a block automatic retransmission request process using a new data indicator indicating block error rate (BLER) and whether the transmission includes retransmission. The method of claim 1, The service access point uses a plurality of target signal-interference ratios, each target signal-interference ratio corresponding to a different data rate, The method further comprises the service access point detecting the data rate and selecting a target signal-interference ratio from the plurality of target signal-interference ratios based on the sensed data rate. The method of claim 4, wherein Adjusting the one or more target signal-interference ratios of the plurality of target signal-interference ratios based on comparing the target indication indicators of the channel quality with the measurement values for the indicators of the channel quality. Way. The method of claim 1, And wherein said wireless access network comprises a radio network controller (RNC) for connecting said service access point to a core network of a telecommunication system, said radio network controller providing said target indication of channel quality. A computer program product comprising a computer readable storage structure for executing computer program instructions, the computer process of which may perform the steps of the method. Determining a new target signal-interference ratio according to an indication of channel quality by comparing a service access point of a wireless access network with a target value for an indication of channel quality and a measurement value for an indication of channel quality; And And using the target signal-interference ratio to provide a power control command to a user terminal device to which the service access point supplies an uplink signal. The method of claim 7, wherein The indicator of channel quality is a block error rate and is measured prior to any hybrid automatic retransmission request process. The method of claim 7, wherein Wherein the indicator of channel quality is a block error rate and the indicator is measured after a hybrid automatic retransmission request process using a new data indicator indicating whether the transmission includes retransmission. The method of claim 7, wherein Computer program code for causing the service access point to perform the step of the service access point detecting the data rate and selecting one target signal-interference ratio from a plurality of target signal-interference ratios based on the sensed data rate; Computer program product. Means for determining a new target signal-interference ratio according to the indication of channel quality by comparing the target value for the indication of channel quality with the service access point a measurement value for the indication of channel quality; And Means for using the target signal-interference ratio to provide a power control command to a user terminal device that provides the uplink signal to the service access point. The method of claim 11, And the channel quality indicator is a block error rate measured before any hybrid automatic retransmission request process. The method of claim 11, The indicator of channel quality is a block error rate and is measured after a hybrid automatic retransmission request process using a new indicator of data indicating whether the transmission includes retransmission. The method of claim 11, The service access point further comprises means for sensing a data rate and selecting one target signal-interference ratio from a plurality of target signal-interference ratios based on the sensed data rate. The method of claim 11, Means for adjusting one or more of the target signal-interference ratios of the plurality of target signal-interference ratios based on comparing the target indication indicators of the channel quality with the measured values for the indicators of the channel quality. Service access point. A user terminal (UE) device for responding to a power control command and for providing an unlink signal; And A wireless access network for connecting the user terminal device to a core network; The wireless access network A service access point responsive to the uplink signal and for providing the power control command; And And a wireless network controller for providing an indication of a target block error rate or other channel quality. The service access point is Means for determining a target signal-interference ratio according to an indication of channel quality by comparing the target value for the indication of channel quality with the service access point a measurement value for the indication of channel quality; And The service access point compares the measured signal-interference ratio value with a target signal-interference ratio to obtain a measured signal-interference ratio value for the uplink signal and provides the power control command to the user terminal device. Means for using the target signal-to-interference ratio to achieve the system. The method of claim 16, The indicator of channel quality is a block error rate measured before any hybrid automatic retransmission request process. The method of claim 16, The indicator of channel quality is a block error rate (BLER), and the indicator is measured after a hybrid automatic retransmission request process using a new data indicator indicating whether the transmission includes retransmission. The method of claim 1, The indicator of channel quality is a block error rate. The method of claim 11, The indicator of channel quality is a service access point which is a block error rate.

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