KR20100024072A - Method for verification of channel quality information and base station supporting the method - Google Patents

Abstract

PURPOSE: A verification method of channel quality information and a base station which supports the method are provided to selectively apply reliable CGI among received CGIs, thereby improving entire data transmission efficiency of a system. CONSTITUTION: In CQI(channel quality information), service supporting of a base station and a terminal is confirmed according to confirmation result of information type. If the base station and terminal supports service according to the information type, whether the CGI satisfies CGI regulation according to characteristic of the information type is confirmed(S740,S750). If the CQI satisfies the CQI regulation, the CQI is applied to a system(S780). If the CQI does not satisfies the CQI regulation, the CQI is discarded(S790).

Description

Method for verification of channel quality information and base station supporting the method}

The present invention relates to a method for identifying channel quality information (CQI) of a portable Internet system and a base station supporting the same.

In the portable Internet system, the terminal measures the quality of a wireless channel, generates channel quality information (hereinafter referred to as "CQI"), and periodically transmits the generated CQI to the base station. After checking the CQI received from the terminal, the base station applies data modulation and coding according to the channel state of the terminal by using an adaptive modulation and coding (AMC) scheme. .

Here, the AMC scheme refers to a data transmission scheme for improving data transmission efficiency of the entire cell by determining a modulation scheme and a coding scheme of different data channels according to channel conditions between the base station and the terminal. The AMC scheme has a plurality of modulation schemes and a plurality of coding schemes, and modulates and codes a data channel signal by combining the modulation schemes and coding schemes.

Typically, a combination of the modulation schemes and coding schemes is called a Modulation and Coding Scheme (MCS), and a plurality of MCS levels from level 1 to level N may be defined according to the number of MCSs. In other words, the AMC scheme is to adaptively determine the MCS level according to the channel state between the base station and the terminal to improve the overall system efficiency.

Since the IEEE 802.16 standard does not adopt a method of checking and correcting an error such as a cyclic redundancy check (CRC) when the terminal transmits a CQI to the base station, does the CQI received from the base station match the CQI transmitted from the terminal It is difficult to check whether the CQI received from the base station is reliable, and when an error occurs in the CQI initially reported to the base station, it is difficult to provide a communication service to the terminal.

In the prior art, as described above, since the error of the CQI received from the terminal cannot be checked, when there is an error in the received CQI, there is a problem of applying an MCS level that does not match the channel state of the terminal. For example, when an MCS level higher than the channel state of the terminal is applied, there is a problem that the terminal cannot decode data transmitted from the base station. In addition, when the MCS level lower than the channel state of the terminal is applied, the data transmitted from the base station can be received and decoded by the terminal, but there is a problem in that the data transmission efficiency is lower than when applying the MCS level suitable for the channel state.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and it is a technical object of the present invention to provide a channel quality information checking method capable of detecting an error in received channel quality information (CQI) and a base station supporting the same.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and by selecting a reliable CQI among the received CQIs so that the MCS level according to the channel state is applied to the channel quality information confirmation method and support that can improve data transmission efficiency It is another technical problem to provide a base station.

Disclosure of Invention The present invention is to solve the above-described problem, and to provide a channel quality information checking method capable of transmitting and receiving CQI through a method capable of error detection and correction when the received CQI is unreliable, and a base station supporting the same. It is another technical task.

In accordance with another aspect of the present invention, a method for confirming channel quality information according to an embodiment of the present invention is a method for confirming channel quality information received from a terminal. Confirming whether the base station and the terminal support a service according to the information type according to a result of checking an information type included in the information type; Confirming, when the base station and the terminal support the service according to the information type, checking whether the received CQI satisfies a CQI reporting rule according to the characteristics of the information type; And confirming, if the CQI reporting rule is satisfied, the received CQI is applied to a system, and if the CQI reporting rule is not satisfied, discarding the received CQI.

In the method for checking channel quality information according to an embodiment of the present invention for achieving the above object, a difference between a physical CINR value of a first CQI received at a current time point and a physical CINR value of a second CQI received in a previous reception period is previously determined. Checking whether the CQI variation range is exceeded; And confirming that the first CQI is applied to the system if the CQI variation range is not exceeded, and discarding the first CQI if the CQI variation range is exceeded.

In accordance with another aspect of the present invention, there is provided a method for confirming channel quality information (CQI) for receiving an OFDMA wireless communication system. Classifying the CQI information type according to a code value; Determining whether the CQI satisfies a valid condition according to the CQI information type; And discarding the occasional CQI when the CQI does not satisfy the valid condition.

In the base station according to an embodiment of the present invention for achieving the above object, in the base station for providing a wireless communication service to the terminal, an error of the CQI based on a reporting rule according to the characteristics of the information type of the CQI received from the terminal A CQI checking unit for determining whether to determine whether to apply the system to the CQI according to a determination result; An MCS setting unit for setting an MCS level applied to a terminal according to the CINR from the CQI checking unit; And

And a scheduler constituting a frame transmitted to the terminal according to the information from the message generator and the MCS setup unit.

The present invention according to the embodiment can improve the overall data transmission efficiency of the system by selectively applying a reliable CQI among the received CQIs.

According to an embodiment of the present invention, when a certain number of CQIs that are continuously received are not all reliable, the entire data transmission of the system can be received by receiving a reliable physical CINR from the terminal through a message to which an error detection and correction scheme is applied. The efficiency can be improved.

According to an exemplary embodiment of the present invention, the unreliable CQI may be discarded from among the received CQIs, thereby preventing the performance degradation of the system due to the system application of the error-prone CQI.

The present invention relates to a method for confirming channel quality information that can improve data transmission efficiency in a mobile Internet system and a base station supporting the same. The present invention relates to an unreliable CQI by checking whether an error of a CQI continuously received from a terminal in the configuration of a base station Will be described in detail with respect to the CQI control unit that discards the card, and selects and applies a reliable CQI, and a detailed description of the other components will be omitted.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention.

According to an embodiment of the present invention, a reliable CQI and an unreliable CQI are distinguished from a plurality of CQIs consecutively received using a characteristic of a CQI in a MAC layer, and a reliable CQI is selectively applied. To improve the transmission efficiency. To this end, the base station according to an embodiment of the present invention, as shown in Figure 1, the band signal processor 110, the transmitter 120, the receiver 130, the antenna 140, the scheduler 150 and the CQI controller ( 200).

Referring to FIG. 1, the scheduler 150 basically determines which rule to distribute available radio resources to each terminal based on feedback information transmitted from a plurality of user terminals, and each user in each frame. Allocates and manages subchannels in the entire burst region of the uplink subframe and the downlink subframe of the current frame for data transmission / reception. That is, after finding the channel of optimal performance for each user terminal, scheduling is performed such that the channel of optimal performance is allocated to the user terminal. The scheduler 150 may include a burst allocator 155 for allocating data bursts according to scheduling.

The burst allocator 155 sequentially allocates downlink data bursts, and the size of the allocated data bursts is determined in consideration of the size of the data to be transmitted, the channel state, and the like. The data burst to be allocated is assigned to a two-dimensional region defined by time and frequency in each subframe region.

The receiver 130 converts signals received through the antenna 140 into baseband signals. For example, the receiver 130 removes and amplifies the noise from the above-described signal for data reception by the base station 100, down converts the amplified signal into a baseband signal, and digitizes the down-converted baseband signal.

In the receiving path, the band signal processor 110 extracts data bits from the digitized signal from the receiver 120 to perform demodulation, decoding, and error correction. The received information is transmitted to an adjacent wired / wireless network (not shown) through an interface (not shown) or transmitted to user terminals serviced by the base station 100 through a transmission path. In addition, the band signal processor 110 encodes input data and control information in the transmission path and outputs the encoded data and control information to the transmitter 120.

The transmitter 120 modulates the data burst allocated by the burst assigner 155 of the scheduler 150, that is, the encoded voice, data, or control information into a carrier signal having a desired transmission frequency or frequencies, and the modulated carrier wave. The signal is amplified to a level suitable for transmission and propagated to the air through the antenna 140. Information on the transmitted data burst is defined in downlink and uplink map information elements DL_MAP_IE and UL_MAP_IE in the map message area.

In addition, the base station 100 includes a map message generator (not shown) for generating a map message in a map message region of a frame based on data burst allocation information (scheduling information).

The OFDMA frame of the portable Internet system is composed of a map (MAP) message area, a downlink (DL) subframe, and an uplink (UL) subframe including the configuration information of the frame. The map message generated by the map message generator is composed of a downlink map (DL_MAP) message for downlink and an uplink map (UL_MAP) message for uplink and is allocated to a map message area of a frame.

The downlink map (DL_MAP) message includes information indicating which downlink data bursts transmitted from the base station 100 are data of which user terminal and in which region the data burst of a specific user terminal is located in a downlink frame. . In addition, the uplink map message includes information indicating in which region the uplink bursts transmitted by the user terminals are located in the uplink frame.

In the portable Internet system based on the IEEE 802.16 standard, the base station 100 needs to receive a CQI feedback from the terminal to know the channel state of the terminal, and the base station allocates a CQI channel (CQICH) to the terminal to receive the CQI feedback from the terminal. give. The terminal generates a CQI by measuring the quality of the radio channel, and periodically transmits the generated CQI to the base station through a CQI channel (CQICH) allocated from the base station (for example, every 1 to 8 frames). The base station 100 provides a communication service to the terminal by setting a power mode, an MCS level, a MIMO mode, etc. applicable to the terminal according to the contents of the CQI received from the terminal.

As described above, the transmission and reception of the CQI does not adopt a method of checking and correcting an error, and the physical layer decodes the radio signal received from the terminal into a digital signal, thereby receiving the received signal from the base station 100. CQI error can not be confirmed.

According to an embodiment of the present invention, a reliable CQI and an unreliable CQI are identified among a plurality of CQIs consecutively received using characteristics of the CQI in the MAC layer. It is intended to improve data transmission efficiency by discarding and applying reliable CQI. In addition, when all of the plurality of received CQIs are unreliable, CQIs may be transmitted and received through a method capable of error checking and correction of a message (for example, a REP_REQ / REQ_RSP message) to apply the CQIs received from the UE. .

To this end, the CQI controller 200 includes a CQI checker 210, a storage 220, a counter 230, a message generator 240, and an MCS setter 250 as shown in FIG. 2. do.

The CQI checking unit 210 checks the contents of the CQI received from the terminal, and whether the terminal or the base station 100 supports the items (eg, MIMO mode, AMC, MDHO, FBSS) included in the received CQI. Check whether or not. In addition, it is checked whether the received CQI satisfies a preset rule (eg, feedback cycle, message reception order, CQI fluctuation up fluctuation range and CQI fluctuation down fluctuation range). Thereafter, the untrusted CQI is discarded according to the verification result, and the trusted CQI is selectively applied.

In addition, when the quantity of the discarded CQI exceeds the preset quantity since the confirming unit 210 cannot trust all the continuously received CQIs, the average Physical CINR values of the discarding CQIs stored in the storage unit 220 are preset. Verify that the range of fluctuations (downward and upward fluctuation ranges) is met.

As a result of the check, if the average Physical CINR values of the discard CQIs satisfy the preset variation range, the discard CQI is set as a reliable CQI and applied to the system. Meanwhile, if the average Physical CINR values of the discard CQIs do not satisfy the preset variation range, all received CQIs cannot be trusted. In this case, the discard count is initialized (discard = 0), and the physical CINR is received from the terminal using the REP_REQ / RSP message. Since the physical CINR received through the REP_REQ / RSP message is reliable, the received physical CINR is applied as the CQI.

Here, the CQI includes Physical CINR information, Effective CINR information, Anchor BS report, MIMO mode information, Extended rtPS bandwidth request, Indication Flag, and Band AMC information, as shown in FIGS. 3A to 3F. The CQI represents 6 bits of information, and the 6 bits of information are coded into 6 bytes and transmitted to the base station 100. The physical layer of the base station 100 converts a radio signal received from the terminal into a digital signal, and extracts and decodes data bits from the digital signal. At this time, the CQI received from the terminal to the base station 100 is decoded into 6 bits.

First, the Physical CINR information shown in FIG. 3A represents information on a carrier to interference and noise ratio (CINR) of a channel measured by a terminal, using -5 dB0 to -3 dB to 28 dB using 5 bits among all 6 bits. Represents a CINR. The characteristic of the Physical CINR is that the first bit of the six bits is always fixed to "0", and represents 32 Physical CINRs using five bits except the first bit.

Here, the physical CINR value is obtained by the following Equations 1 and 2, and for a plurality of frames for each period (eg, 1, 2, 4, 8 frames) in which a CQI including Physical CINR information is reported ( For example, an average value of CINR values measured in 16 frames) is coded and transmitted to the base station 100.

[Equation 1]

In Equations 1 and 2, α denotes a reflection ratio of Physical CINR that determines how much the Physical CINR value measured in one frame is reflected in the average Physical CINR value, for example, the average Physical CINR value for 16 frames. In case of reporting to the base station through the CQI, the physical CINR of the current frame is reflected by 1/16 in the average physical CINR.

The physical CINR is changed between -3dB and 28dB according to the change in the channel state of the frame. When α is set to “1”, the channel state of each frame is reflected in the physical CINR value of the CQI and reported continuously. Variation in the physical CINR value between the CQIs may be large.

However, when α is set to "1/16", the average Physical CINR value for 16 frames is calculated, and the calculated average Physical CINR value is reported to the base station. In this case, the fluctuation range in the physical CINR values between the CQIs becomes smaller than when the α is set to “1” so that the average physical CINR values among the continuously received CQIs fluctuate within a certain range (downward fluctuation range and upward fluctuation range). Will be.

In more detail, when the terminal moves at 3 km (pedestrian movement speed), α is set to “1/16” and the CQI is reported to the base station every 8 frames. The average physical CINR values of the CQIs received at were changed within the range of -2dB downward fluctuation to + 6dB upward fluctuation. For example, if the average Physical CINR value of the CQI reported to the base station in the previous period (n period) is 5dB, the average Physical CINR value of the CQI reported to the base station at the present time point (n + 1 period) is at least 3dB to maximum It will have a value of 11 dB.

If the average Physical CINR value of the CQI reported to the base station in period n is 5 dB, and the average Physical CINR value of the CQI reported to the base station in period n + 1 is less than 3 dB or exceeds 11 dB, this is the received CQI. This means that an error has occurred. In this case, since the received CQI is not reliable, the corresponding CQI is discarded and the CQI applied to the previous period (n period) is maintained. Here, the previously applied CQI means a CQI applied to the system because it is determined to be reliable among the first received CQI or the continuously received CQI.

In the present invention according to the embodiment is to limit the apparatus and method that can determine the error of the CQI received from the terminal by using the feature that the average physical CINR value of the CQI fluctuates within a certain range, the above-mentioned average physical CINR down The fluctuation range and the upward fluctuation range may vary according to the moving speed of the terminal, the channel environment, and the α value.

The effective CINR information shown in FIG. 3b represents MCS information applicable to the terminal, and represents the MCS of QPSK 1/2 repetition 6 to 64QAM 5/6 using 4 bits among all 6 bits (0b00XXXXX). The characteristic of the effective CINR is that the first and second bits of the six bits are always fixed to "0", and the effective CINR information is represented by using four bits except the first and second bits.

As shown in FIG. 3A and FIG. 3B, as described above, the CINR CQI representing the Physical CINR information and the Effective CINR information has a feature in which the first bit of the 6 bits is always fixed to “0”. For example, if a check result of the CQI confirming unit 210 indicates that the first bit of the received CQI is set to “1” in the CQI feedback cycle in which the Physical CINR and the Effective CINR are reported, an error occurs in the received CQI. It means. In this case, since the received CQI is not reliable, the CQI is discarded and the previously applied CQI is maintained.

The Anchor Base Station (BS) report, shown in FIG. 3C, is used when the macro diversity handover (MDHO) or fast BS switching (FBSS) is required. Is sent to. The feature of the Anchor BS report is that the first bit of the six bits is always fixed at "1" and the second bit is always fixed at "0". That is, information about macro diversity handover or fast base station switching is indicated by using (0b10XXXXX) four bits except for the first and second bits.

For example, in a situation where the terminal or the base station 100 does not support the function of for macro diversity handover (MDHO) or fast BS switching (FBSS), the CQI received from the terminal is used. If the above information is included, this means that an error has occurred in the CQI received from the UE. In this case, since the CQI check unit 210 cannot trust the received CQI, it discards the corresponding CQI.

The MIMO mode information illustrated in FIG. 3D indicates a MIMO mode (for example, STTD and SM) applicable to the terminal. The characteristic of the MIMO mode information is that the first bit of the six bits is always fixed to "1". That is, MIMO mode information applicable to the UE is indicated by using five bits except the first bit (0b1XXXXX).

For example, in a situation where the terminal or the base station 100 does not support the MIMO mode, if the CQI received from the terminal includes information on the MIMO mode, this means that an error has occurred in the CQI received from the terminal. In this case, since the CQI check unit 210 cannot trust the received CQI, it discards the corresponding CQI.

The band width ratio (BWR) information illustrated in FIG. 3E includes Extended rtPS bandwidth request and Indication Flag Feedback information. The biggest feature of this BWR is that it cannot be received continuously. In detail, when the CQI is received every 8 frames, if the CQI received in the previous period (n frames) includes the BWR, the currently received CQI (n + 8 frames) may not include the BWR.

For example, if the CQI received by the CQI confirming unit 210 includes the BWR in the CQI received in the previous cycle and the CQI in the current cycle includes the BWR, the CQI received in the current cycle cannot be trusted. Discard.

In addition, BWR (Band Width Ratio) information is fixed to "1" at first to third bits among six bits. That is, the first to third bits are always fixed to "1" and use the remaining three bits (0b111XXX) to indicate extended rtPS bandwidth request and Indication Flag Feedback information.

3F shows Band AMC transition information. The band AMC transition information includes information on switching from a normal subchannel to a AMC, switching from an AMC to a basic subchannel, and switching an AMC band.

The biggest feature of the band AMC transition information is that the order of transmission and reception of messages is determined. In order to receive the band AMC transition information through the CQI, first, a procedure for requesting the AMC mode change using the Enhanced Band AMC Report TLV of the REP_REQ / RSP message must be performed by the terminal or the base station.

If the received CQI does not match the transmission / reception order of the band AMC transition information, it means that an error has occurred in the CQI received from the UE. In this case, since the CQI check unit 210 cannot trust the received CQI, it discards the corresponding CQI.

As described above, the CQI that is determined to be unreliable according to the CQI confirming unit 210, that is, the discard CQI is not immediately discarded, and the preset quantity is stored in the storage unit 220. The diskette CQI stored in the storage unit 220 is used as the basis for the confirmation when additional confirmation of the CQI trust is required. Here, the number of diskette CQIs stored in the storage unit 220 is variable. In the present invention, for example, the number of diskette CQIs stored in the storage unit 220 is set to three.

Subsequently, the counter 230 counts the quantity of the discarded CQI and the quantity of the discarded CQI stored in the storage unit 220, and provides counting information to the CQI confirming unit 210.

When the CQI confirming unit 210 confirms that the average physical CINRs of the discarded CQIs do not satisfy the preset variation range, the message generator 240 may not trust all received CQIs. By generating an applied message (eg, REP_REQ / RSP message), the base station 100 generates a message so that the base station 100 can receive a reliable physical CINR from the terminal.

The MCS setting unit 250 sets the MCS according to the CINR information included in the CQI applied to the system when the CQI confirming unit 210 confirms that the received CQI is reliable.

The base station 100 according to an embodiment of the present invention including the above-described configuration uses a MAC layer (CQI) of reliable CQI and unreliable CQI among a plurality of CQIs continuously received by using characteristics of the CQI received from the UE. Layers, and by applying reliable CQI can improve the overall data transmission efficiency of the system. In addition, when all the continuously received CQIs are unreliable, a reliable physical CINR can be received from the terminal through a message to which an error detection and correction method is applied, thereby improving the overall data transmission efficiency of the system.

In the above-described embodiment, the CQI control unit 200 is described as being included in the base station 100 as an independent component, but the CQI control unit 200 is integrated into other components (eg, the scheduler) of the base station 100. Can be implemented.

Hereinafter, a method for checking channel quality information (CQI) according to embodiments of the present invention will be described with reference to FIGS. 4 to 9.

4 and 5 are flowcharts illustrating a method for checking channel quality information (CQI) according to a first embodiment of the present invention.

4 and 5, when the CQI is received from the UE (S100), it is checked whether the received CQI includes CINR information (S110). Here, the method for checking whether the CQI includes the CINR information is as described above. Since the first bit of the 6 bits (0b0XXXXX) is “0”, the CQI is CINR if the first bit of the 6 bits is “0”. If the first bit is "1", it can be seen that the received CQI does not include CINR information.

As a result of the check of S110, if the received CQI includes CINR information, it is necessary to confirm whether the feedback type is Effective CINR information or Physical CINR information. To this end, first, it is checked whether the CINR information of the received CQI is Effective CINR information (S120).

As a result of the check of S120, if the feedback type of the received CQI is not Effective CINR information, it is checked whether the feedback type of the CQI is Physical CINR information (S130). Here, the method for checking whether the received CQI is a Physical CINR or an Effective CINR is to check whether the first bit is 0 out of 6 bits, and then check whether the second bit is 0 out of 6 bits. Therefore, it is confirmed whether the effective CINR. In particular, in the case of Physical CINR, if the first bit of six bits is 0, that is, all 32 types (2 ^ 5) represented by 5 bits are included, the presence or absence of an error may be checked by referring to FIG. have.

If the feedback type of the received CQI is not the physical CINR information, as a result of checking in S130, an error occurs in the received CQI and the CQI cannot be trusted, so the corresponding CQI is discarded (S220).

On the other hand, when the check result of the step S130, when the feedback type of the CINR is physical CINR information, the PCINR check procedure for checking whether there is an error in the physical CINR information, that is, whether the physical CINR information can be trusted (S140).

Returning to S120 again, if the feedback type of the received CQI is Effective CINR information, it is checked whether the first and second bits of the 6 bits received from the terminal are set to “0” (0b00XXXX) (S200). . Here, when both the first and second bits of the 6 bits are not set to "0", it can be seen that the received CQI does not include Effective CINR information.

As a result of checking in S200, if both the first and second bits of the 6 bits are not set to “0”, an error occurs in the received CQI and the CQI is not reliable, so the corresponding CQI is discarded (S220).

On the other hand, if the check result of S200, if both the first and second bits of the 6 bits is set to "0", since the received CQI includes the effective CINR information, and confirms whether the terminal and the base station supports the AMC (S210) .

As a result of checking in S210, if the UE and the base station support the AMC, the received CQI is applied to the system (S230). If at least one of the terminal and the base station does not support the AMC, an error is generated in the received CQI and the CQI is generated. Since it is not reliable, the corresponding CQI is discarded (S220).

Returning to S110 again, if the received CQI does not include CINR information, it is checked whether the feedback type of the CQI is the anchor BS (S150).

As a result of checking in S150, when the CQI feedback type is an anchor BS, it is checked whether the base station supports the anchor BS (S300).

If the base station does not support the Anchor BS as a result of the check in S300, an error occurs in the received CQI and thus the CQI cannot be trusted, and the corresponding CQI is discarded (S220). On the other hand, if the base station supports the anchor BS as a result of the check in S300, the received CQI is applied to the system (S230).

Returning to S150 again, as a result of confirming whether the feedback type of the CQI is the anchor BS, when the CQI feedback type is not the anchor BS, it is checked whether the CQI feedback type is the MIMO mode (S160).

As a result of S160, when the CQI feedback type is the MIMO mode, it is checked whether the terminal and the base station support the MIMO mode (S400).

If at least one of the terminal and the base station does not support the MIMO mode, as a result of the checking of the S400, an error occurs in the received CQI and thus the CQI cannot be trusted, and the corresponding CQI is discarded (S220).

On the other hand, if the UE and the base station supports the MIMO mode, as a result of S400, it is checked whether the feedback cycle of the currently received CQI is a feedback cycle including the MIMO mode information (S410).

As a result of the check in S410, if the feedback cycle does not include MIMO mode information, an error occurs in the received CQI and thus the CQI cannot be trusted. Therefore, the corresponding CQI is discarded (S220), and the feedback cycle includes MIMO mode information. If is applied to the received CQI to the system (S230).

Returning back to S160, as a result of checking whether the CQI feedback type is the MIMO mode, when the CQI feedback type is not the MIMO mode, it is checked whether the CQI feedback type is the Band AMC transition information (S170).

As a result of the checking of S170, when the CQI feedback type is Band AMC transition information, as described above, it is checked whether a message transmission / reception rule of a message transmitted and received between the terminal and the base station for the Band AMC transition is satisfied (S500).

If the received CQI does not satisfy the rule for transmitting / receiving the band AMC transition information, as a result of S500, an error occurs in the received CQI and the CQI cannot be trusted, so the corresponding CQI is discarded (S220).

On the other hand, if the check result of S500, the received CQI satisfies the rules for transmitting and receiving the band AMC transition information is applied to the system (S230).

Returning to S170 again, as a result of checking whether the CQI feedback type is Band AMC transition information, when the CQI feedback type is not Band AMC transition information, it is checked whether the CQI feedback type is BWR (S180).

If the CQI feedback type is not BWR as a result of checking of S180, as described above, it means that the received CQI does not include all information of CINR, Anchor BS, MIMO mode, Band AMC transition, and BWR. In this case, since an error occurs in the received CQI and the CQI cannot be trusted, the corresponding CQI is discarded (S220).

On the other hand, when the check result of S180, when the CQI feedback type is BWR, it is checked whether the BWR is ertPS (S600).

As a result of checking in S600, when the CQI feedback type is ertPS, it is checked whether the BWR rule is satisfied (S630). Since the CQI reported to the base station at regular intervals cannot include BWR information continuously, it is checked whether the BWR is included in the CQI reported in the previous period. As a result of the check, if BWR information is not included in the CQI reported in the previous cycle, the ertPS information included in the CQI received at the present time means that no error has occurred. In this case, the received CQI is applied to the system (S230).

On the other hand, if the check result of S630 does not satisfy the rules of the BWR, that is, if the CQI reported in the previous cycle includes the BWR, an error occurs in the ertPS information included in the received CQI and thus the CQI cannot be trusted. Process the discard (S220).

Returning to S600, if it is confirmed that the CQI feedback type is not ertPS, it is checked whether it is Indication Flag feedback (S610).

As a result of checking in S610, if the CQI feedback type is Indication Flag feedback, it is checked whether the base station supports Indication Flag feedback (S620).

If the base station does not support Indication Flag feedback as a result of checking in S620, an error occurs in the received CQI and thus the CQI cannot be trusted, and the corresponding CQI is discarded (S220).

On the other hand, if the check result of S620, the base station supports Indication Flag feedback, if the check result of the 600, the CQI feedback type is ertPS, and performs the same S630 applied to satisfy the BWR rule.

As a result of checking whether BWR is included in the CQI reported in the previous cycle, if the BQ information is not included in the CQI reported in the previous cycle, an error occurs in the Indication Flag feedback information included in the CQI received at the present time. Since it is not, the received CQI is applied to the system (S230).

On the other hand, if the check result of S630, if the CQI reported in the previous cycle includes the BWR, an error occurs in the Indication Flag feedback information included in the received CQI, so that the CQI is unreliable, the corresponding CQI is discarded (S220). ).

In the above-described method for checking channel quality information according to the first embodiment of the present invention, a MAC layer may be configured to include reliable CQI and unreliable CQI among a plurality of CQIs continuously received by using characteristics of the CQI received from the UE. ), And by applying a reliable CQI can improve the overall data transmission efficiency of the system.

6 is a flowchart illustrating a method of checking channel quality information (CQI) according to a second embodiment of the present invention, and FIGS. 7 to 9 are error checking methods of physical CINRs included in channel quality information (CQI) from a terminal. It is a figure which shows.

Prior to the description with reference to the drawings, the CQI reported from the terminal to the base station includes physical CINR information, Effective CINR information, Anchor BS report, MIMO mode information, Extended rtPS bandwidth request, Indication Flag, and Band AMC transition information as described above. The CQI is most often used for reporting Physical CINR among these various information.

Since physical CINR information represents information on channel state measured by the terminal, the physical CINR information reported by the terminal should be reliable in order to obtain an optimal data transmission efficiency by applying an MCS suitable for the channel state at the base station.

The method for confirming channel quality information according to the second embodiment of the present invention distinguishes reliable and unreliable Physical CINR information from Physical CINR information of CQIs continuously reported from a terminal to a base station, and is reliable. By applying physical CINR information to improve the data transmission efficiency.

In addition, when all the physical CINR information continuously received is unreliable, it is possible to receive reliable physical CINR information from the terminal through a message to which an error detection and correction method is applied to improve the overall data transmission efficiency of the system. do.

In the following description, CQI is defined as including Physical CINR information. First, referring to FIG. 6, if a CQI is received from the UE, it is checked whether the CQI is the first CQI after the channel quality information channel (CQICH) is allocated to the UE (S700).

As a result of confirmation of S700, when the first CQI is received, the previously received CQI is applied to the system, and the discard count is initialized (discard = 0) (S710).

Thereafter, the reception period (1 to 8 frames) of the CQI is checked (S720). The CQI is periodically reported to the base station according to the frame period set in S720. For example, when the CQI is reported from the UE when the reception period is not preset, it may be regarded as an error in the received CQI.

Returning to S700 again, if the received CQI is not the first CQI, since the CQI has been received before the present time, the procedure of S710 is omitted and the procedure of S720 is performed.

After the operation of S720, the value of α (1 to 1/16) according to Equations 1 and 2 is checked (S730). Here, when α is 1, it means that the physical CINR value according to the channel state measured in the current frame is included in the CQI. When α is 1/16, the channel state is measured in 16 frames including the current frame. Mean means to include the average physical CINR value according to the CQI. In other words, the smaller α is, the smaller the variation of the Physical CINR value included in the CQI.

Thereafter, it is checked whether the physical CINR value of the received CQI exceeds a preset CQI upward variation range (S740).

As a result of the check in S740, if the physical CINR value does not exceed the preset CQI upward fluctuation range, it is checked whether the physical CINR value of the received CQI exceeds the preset CQI downward fluctuation range (S750).

Here, the up-range range and down-range range of the preset CQI represents the physical CINR down-range range and the up-range range, it can be changed according to the moving speed, channel environment, α value of the terminal.

In an embodiment of the present invention, in an environment where the UE moves at 3 km (pedestrian movement speed), α is set to “1/16”, and the physical CINR is lowered by applying the experimental result of the environment where the CQI is reported to the base station every 8 frames. For example, the fluctuation range is -2dB and the physical CINR upward fluctuation range is + 6dB.

As a result of checking in S750, if the physical CINR value of the received CQI does not exceed a preset CQI up-change range, the CQI received from the UE is received without errors and is reliable. In this case, the discard count is initialized (S760), and the advanced CQI, that is, the first CQI having been checked for error, is set as the received CQI (S770). Thereafter, the received CQI is applied to the system (S780).

Returning to S740 again, if it is confirmed that the physical CINR value exceeds the preset CQI upward fluctuation range, or if the physical CINR value exceeds the preset CQI downward fluctuation range, the received CQI generates an error and is reliable. Since it is not possible, the received CQI is discarded (S790).

More specifically, as shown in FIG. 7, when the physical CINR value of the first CQI reported in the N-th period is 5dbB and the physical CINR value of the second CQI reported in the N + 1th period is 20 dB. When comparing the physical CINR values of the first CQI and the second CQI by applying a preset physical CINR upward fluctuation range (+6 dB), since the physical CINR value of the second CQI is +15 dB greater than the physical CINR value of the first CQI, the CQI It can be seen that the upward variation range of (+ 6dB) is exceeded. In this case, according to the check result of S740, the CQI reported in the N + 1 period is discarded (S790).

Although not shown in the figure, it is assumed that the physical CINR value of the first CQI reported in the Nth period is 5dbB and the physical CINR value of the second CQI reported in the N + 1th period is 0dB, and the preset physical CINR is down. Comparing the physical CINR values of the first CQI and the second CQI by applying the fluctuation range (-2 dB), since the physical CINR value of the second CQI is -5 dB smaller than the physical CINR value of the first CQI, the downward fluctuation range of the CQI (- It can be seen that the 2dB) is exceeded. In this case, the CQI reported in the N + 1 period may be discarded according to the check result of S750 (S790).

After the N + 1 period, when the physical CINR value of the third CQI reported in the N + 2 period is 7 dB, the physical CINR values of the first CQI and the second CQI are applied by applying a preset physical CINR upward variation range (+6 dB). Compare At this time, the discarded second CQI is excluded from comparison. As a result, it can be seen that since the physical CINR value of the third CQI is +2 dB greater than the physical CINR value of the first CQI, the upward variation range (+6 dB) of the CQI is not exceeded.

In this case, since the Physical CINR value of the third CQI does not exceed a preset CQI up-range and down-range range, the third CQI is received without errors and can be reliably. If the received third CQI does not generate an error and is reliable, the discard count is initialized (S760), and the third CQI having been checked for an error is set as the received CQI (S770). Thereafter, the received CQI is applied to the system (S780).

Returning to S790 again, if the received CQI is discarded according to the check result of S740 and S750, the discard count is increased (S800).

Thereafter, it is checked whether the increased discard count is greater than or equal to a set threshold (S810). Here, the allowable value of the discard count is that an error is continuously generated in the received CQIs so that the quantity of discarded CQIs is set. According to an embodiment of the present invention, the allowable count of the discard count is set to 3 as an example. It was. When the tolerance value of the discard count is set to 3, an error occurs in three CQIs in succession, and when three discard CQIs are collected, it is checked whether physical CINR values between the discard CQIs exceed a predetermined CQI variation range.

As a result of checking in S810, when the discard count is less than the allowable value, the discard CQI is stored (S820).

On the other hand, as a result of checking in S810, if the discard count is more than the allowable value (for example, 3), an error is continuously generated and the discard CQI becomes a preset quantity, so that the physical CINR values between the discard CQIs are set upward. Check whether the variation exceeds the range (S830).

As a result of the check in S830, if the physical CINR values of the discard CQIs do not exceed the preset CQI upshift range, it is checked whether the physical CINR values between the discard CQIs exceed the preset CQI downshift range (S840).

Referring to FIG. 8, when the first CQI having a physical CINR value of 5 dbB is identified as a reliable CQI and applied to the system, the second CQI having a Physical CINR value of 20 dB and a Physical CINR value of 21 dB are described. Compared to the first CQI having a physical CINR value of 5dbB and the third CQI having a physical CINR value of 19dB, all of the third CQI has a predetermined CICI upstream variation range (+ 6dB).

As described above, when the number of discard CQIs continuously reaches the allowable value of the discard count, it is checked whether physical CINR values between stored discard CQIs exceed a preset CQI up-range range and a down-range range (S830 and S840).

Comparing the physical CINR values of the discard CQIs, the comparison with the first CQI having a physical CINR value of 5dbB exceeded the preset CQI up-range range and the down-range range, but in the comparison between the physical CINR values of the discard CQIs. It can be seen that CQI does not exceed the upward fluctuation range (+ 6dB) and the downward fluctuation range (-2dB). As described above, when there is a correlation between discarded CQIs, the discarded CQI can be trusted.

In S830 and S840, the most recent (Nth) CQI and the immediately preceding (N-1st) CQI among the N discard CQIs are compared, and then, the N-1 th CQI and the N-2 th CQI are compared. As a result of comparing the threshold value among the N discarded CQIs, if the differences are all within the CQI variation range, the discarded CQI is trusted and the PCINR of the last discarded N-th CQI is applied to the system. Do. On the other hand, as a result of comparing the threshold amount (discard threshold), if any one is not satisfied, PCINR is received through a separate procedure.

Specifically, if the physical CINR values between the discarded CQIs do not exceed the preset CQI up-range and down-range ranges, the N-CQIs consecutively discarded are determined as the reference quantity (S830 and S840). check whether it is compared by discard threshold (S860). Specifically, it is checked whether the most recent (Nth) CQI and the immediately preceding (N-1st) CQI of the N diskette CQIs are compared, and the N-1st CQI and the N-2nd CQI are compared. It is checked whether N discarded CQIs are compared by a threshold amount.

As a result of checking in S860, when the discard CQI is compared by the reference quantity, the discard count is initialized (S870), and the discard CQI is set as the received CQI (S880). Thereafter, the discarded CQI is applied to the system (S780).

Here, the reference quantity of the compared diskette CQIs means the number of recent diskette CQIs to be compared among the diskette CQIs stored in the storage unit. Among the card CQIs, the latest three discard CQIs are compared with each other.

On the other hand, if the check result of S860 does not compare the discard CQI by the reference quantity, the discard count is initialized (S760), and a message method (eg, REP_REQ / RSP message) capable of error detection and error correction is performed. Physical CINR information of the CQI is received from the terminal (S850). Subsequently, when physical CINR information of the CQI is received through a message capable of error detection and correction, the received CQI is reliable and is applied to the system (S780).

In addition, as a result of confirming S830 and S840, as illustrated in FIG. 9, physical CINR values of the discard CQIs exceed a preset CQI upward variation range (+6 dB), or physical CINR values of the discard CQIs are preset. If the CQI downward fluctuation range (-2 dB) is exceeded, there is no correlation between the discard CQIs, and thus all recently received CQIs are unreliable.

In this case, the discard count is initialized (S760), and physical CINR information of the CQI is received from the terminal by using a message method (for example, a REP_REQ / RSP message) capable of error detection and error correction (S850). Then, if physical CINR information of the CQI is received through a message capable of error detection and correction, the received CQI is reliable and is applied to the system (S780).

Since the IEEE 802.16 standard does not adopt a method of checking and correcting an error such as a cyclic redundancy check (CRC) when the UE transmits a CQI to the base station, the UE cannot verify whether the received CQI is reliable. If an error occurs in the CQI, it is difficult to provide a communication service to the terminal.

In the method of confirming channel quality information according to the second embodiment of the present invention described above, a terminal uses a message method (for example, a REP_REQ / RSP message) capable of error detection and error correction when there is no correlation between discard CQIs. Although it has been described that the physical CINR information of the CQI can be received from the above, this is an exemplary embodiment. A method of checking and correcting an error, such as a cyclic redundancy check (CRC), is initially reported from the UE (REP_REQ). / RSP) can be used to send and receive CQI between the terminal and the base station. Receiving a CQI from the terminal using a method of checking and correcting an error may prevent an error of the CQI initially reported to the base station.

Configuration and operation as described above is not limited to the claims of the present invention as an embodiment, and various changes and modifications are possible within the scope of not changing the technical spirit of the present invention in the field to which the present invention belongs. It is obvious to those who are engaged.

It is apparent to those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit and essential features of the present invention. Accordingly, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative. The scope of the invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the invention are included in the scope of the invention.

1 is a diagram illustrating a base station according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of the CQI control unit shown in FIG. 1. FIG.

3A-3F illustrate CQI messages.

4 and 5 are flowcharts illustrating a method for checking channel quality information (CQI) according to a first embodiment of the present invention.

6 is a flowchart illustrating a method of checking channel quality information (CQI) according to a second embodiment of the present invention.

7 to 9 are diagrams illustrating an error checking method of physical CINR included in channel quality information (CQI) from a terminal.

<Explanation of symbols for the main parts of the drawings>

100: base station 110: band signal processing unit

120: transmitter 130: receiver

140: antenna 150: scheduler

155: burst allocation unit 200: CQI control unit

210: CQI check unit 220: storage unit

230: counter 240: message generating unit

250: MCS setting unit

Claims (27)

In the method of confirming the channel quality information received from the terminal, Confirming whether the base station and the terminal support a service according to the information type according to a result of checking an information type included in channel quality information (CQI) received at a predetermined frame period from the terminal; Confirming, when the base station and the terminal support the service according to the information type, checking whether the received CQI satisfies a CQI reporting rule according to the characteristics of the information type; And As a result of the check, if the CQI reporting rule is satisfied, the received CQI is applied to a system, and if the CQI reporting rule is not satisfied, discarding the received CQI, characterized in that the channel quality information is confirmed. Way. The method of claim 1, The CQI reporting rule includes a reception period and a reception order of the information type. The method of claim 1, wherein the service support check step, And when the base station and the terminal do not support the service according to the information type, discarding the received CQI. The method of claim 1, And storing the determined CQIs in the order of occurrence before discarding the received CQIs. The method of claim 1, The information type is at least one of Physical CINR, Effective CINR, Anchor BS report, MIMO mode, Extended rtPS bandwidth request, Indication Flag, and Band AMC transition, In the step of checking whether the CQI reporting rule is satisfied, the channel quality information checking method, characterized in that for each information type not to satisfy the CQI reporting rule. The method of claim 5, wherein When the extended rtPS bandwidth request information type or the indication flag information type is included in the received CQI at the present time, Determining whether a reception period of a previous CQI includes the extended rtPS bandwidth request information type or an indication flag information type; And confirming that the CQI received at the current time is discarded if the Extended rtPS bandwidth request information type or the indication flag information type is included in the reception period of the previous CQI. The method of claim 5, wherein When the band AMC transition information type is included in the received CQI at the present time, Checking whether a message for changing an AMC mode has been transmitted / received between the terminal and the base station before the reception of the CQI; And confirming that the CQI received at the present time is discarded when a message for changing the AMC mode is not transmitted or received. Checking whether a difference between the physical CINR value of the first CQI received at the present time point and the physical CINR value of the second CQI received in the previous reception period exceeds a preset CQI variation range; And And if it is determined that the CQI variation range is not exceeded, applying the first CQI to the system and discarding the first CQI if the variation range exceeds the CQI variation range. 9. The method of claim 8, prior to the discarding of the first CQI. Counting a quantity of the first CQI whose discard has been determined; And And storing the discarded first CQI in the order of occurrence. The method of claim 9, When discarding is determined and the quantity of the stored first CQI is equal to or greater than the set quantity, confirming whether a difference between the physical CINR values of the stored first CQIs exceeds the CQI variation range; And And determining whether to apply one of the stored first CQIs to the system according to the verification result. The method of claim 10, And if the physical CINR values of the stored first CQIs do not exceed the CQI variation range, the most recently received first CQI among the stored first CQIs is applied to the system. The method of claim 11, And when applying any one of the stored CQIs to the system, initializing a count of the CQIs for which revocation has been determined. The method of claim 10, And receiving a third CQI through a message of an error detection and correction method when the physical CINR values of the stored CQIs exceed the CQI variation range. The method of claim 13, And the message of the method capable of error detection and correction is a REP_REQ / RSP message. The method of claim 13, And receiving a report of the third CQI through a message in a manner capable of detecting and correcting the error, initiating a count of the discarded CQI. The method of claim 8, Before checking whether the CQI variation range is exceeded, Confirming a reception period of the CQI; And And determining a reflection ratio of the physical CINR as a reference for calculating the average physical CINR value. The method of claim 8, The CQI variation range is changed according to a moving speed of a terminal, a channel state, and a method of calculating the physical CINR value. A method for checking channel quality information (CQI) for an OFDMA wireless communication system, Receiving channel quality information (CQI) and classifying a CQI information type according to a code value of the CQI; Determining whether the CQI satisfies a valid condition according to the CQI information type; And And discarding the received CQI when the CQI does not satisfy the valid condition. The method of claim 18, The valid condition includes at least one of a code value of the CQI, a reporting period of the CQI, a reception time of the CQI, a reception order of the CQI information type, and a variation range of the code value of the CQI. How to check your information. In the base station for providing a wireless communication service to the terminal, A CQI checking unit determining whether an error occurs in the CQI based on a reporting rule according to a characteristic of the information type of the CQI received from a terminal, and determining whether to apply the system to the CQI according to a determination result; An MCS setting unit for setting an MCS level applied to the terminal according to the CINR from the CQI checking unit; And And a scheduler constituting a frame transmitted to the terminal according to the information from the message generator and the MCS setup unit. The method of claim 20, The CQI confirmation unit confirms whether or not the service support according to the information type of the CQI, and determines whether to apply the system based on the CQI. The method of claim 20, The base station, characterized in that, if there is no error, the CQI is applied to the system, and if there is an error, the CQI is discarded. The method of claim 22, The CQI checking unit checks whether the comparison result of the physical CINR value of the CQI received at the present time point and the physical CINR value of the CQI received in the previous reception period exceeds a CQI variation range having a certain range, As a result of the check, if the physical CINR value of the CQI received at the current time does not exceed the CQI variation range, the CQI received at the current time is applied to the system, and if the CQI variation range is exceeded, the CQI received at the current time The base station, characterized in that for processing the discard. The method of claim 23, The checker compares the physical CINR values of the discarded CQIs with each other when the number of CQIs is continuously discarded, and checks whether the CQI variation range is exceeded, and whether the system is applied to the discarded CQIs according to the verification result. The base station, characterized in that for determining. The method of claim 24, And if the physical CINR values of the discarded CQIs do not exceed the CQI variation range, the base station is configured to apply the latest discarded CQI to the system. The method of claim 24, The base station, characterized in that the CQI is reported through a message that can be detected and corrected when the physical CINR values of the discarded CQI exceeds the CQI variation range. The method of claim 20, A storage unit for storing the discarded CQI according to the determination result of the CQI checking unit; A counter counting a quantity of discarded CQIs stored in the storage unit; And The base station further comprises a message generating unit for generating a message of a method capable of error detection and correction.

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