KR20100020884A - Method for transmitting channel quality indicator - Google Patents

Abstract

PURPOSE: A method for transmitting channel quality indicator is provided to improve the system performance by minimizing the performance degradation of a scheduler. CONSTITUTION: A signal is received through a plurality of legacy system bands. The CQI(Channel Quality Indicator) about a plurality of legacy system bands uses the CQI transmission mode which is similar to each legacy system for each bandwidth. In case each legacy system for each bandwidth CQI is transmitted through the uplink shared channel, each legacy system for each bandwidth CQI whole is transmitted. In case each legacy system for each bandwidth CQI is transmitted through the uplink control channel, each legacy system for each bandwidth CQI is successively transmitted to the fixed number unit.

Description

Method for Transmitting Channel Quality Indicator

The present invention relates to a method for transmitting a channel quality indicator (CQI) in a mobile communication system, and more particularly, to a method for efficiently generating and transmitting a channel quality indicator by a user equipment in a system that performs communication using a plurality of legacy system bands. It is about.

 For efficient communication, the receiving side is required to feed back channel information to the transmitting side. Usually, downlink channel information is sent uplink, and uplink channel information is sent downlink. This channel information is referred to as a channel quality indicator, that is, CQI. Such a CQI can be generated in several ways.

For example, a method of quantizing a channel state as it is, a method of calculating and transmitting a Signal to Interfrerence and Noise Ratio (SINR), and a method of notifying a state in which a channel is actually applied, such as a modulation coding scheme (MCS). There is this.

Among the various CQI generation methods, we can see many cases in which CQI is generated based on MCS. An example of this is CQI generation for a transmission scheme such as HSDPA in 3GPP. As described above, if the CQI is generated based on the MCS, the MCS includes a modulation scheme, a coding scheme, and a coding rate accordingly. Therefore, since the CQI needs to be changed according to the change in the modulation scheme and the coding scheme, at least one CQI is required per codeword unit.

If MIMO is applied to the system, the number of required CQIs also changes. That is, since the MIMO system generates multiple channels using multiple antennas, multiple codewords are usually available. Therefore, multiple CQIs must be used. When a plurality of CQIs are used in this way, the amount of control information accordingly increases proportionally.

1 is a conceptual diagram of CQI generation and transmission.

The terminal measures downlink quality and reports the selected CQI value to the base station through the uplink control channel. The base station performs downlink scheduling (terminal selection, resource allocation, etc.) according to the reported CQI. Here, the CQI value may include a SINR of a channel, a carrier to interference and noise ratio (CINR), a bit error rate (BER), a frame error rate (FER), and the like. In addition, in the MIMO system, RI (Rank Information), PMI (Precoding Matrix Information), and the like may be added as information reflecting channel status.

In the mobile communication system, in order to maximize the use of a given channel capacity of a channel, link adaptation is used to adjust MCS and transmission power according to a given channel. In order to perform such link adaptation at the base station, the user should feedback the channel quality information to the base station.

If the frequency band used by the system exceeds the coherence bandwidth, the channel will show a drastic change in the bandwidth used. In particular, in a multi-carrier system such as Orthogonal Frequency Division Multiplexing (OFDM), multiple sub-carriers exist within a given bandwidth, and modulated symbols are transmitted through every sub-carrier. For optimal channel transmission, channel information for each subcarrier is transmitted. Accordingly, since a feedback amount of channel information is rapidly increased in a multicarrier system having a large number of subcarriers, various methods have been proposed to reduce such control overhead of control signals.

On the other hand, the number of CQI increases the number of transmissions in various dimensions, which can bring a lot of overhead.

First, the increase of CQI in the spatial dimension is as follows. In MIMO, when multiple codewords are transmitted through multiple layers, multiple CQIs are required. For example, in 3GPP LTE, up to two codewords can be used in MIMO, and two CQIs are required. If the CQI of one codeword consists of N bits and two codewords, the CQI must consist of a total of 2 * N bits. Since the CQI is transmitted by all users who need to inform the channel state, it takes a large part from the viewpoint of the entire radio resource. Therefore, it is desirable to reduce this CQI to a minimum amount in terms of channel capacity.

Second, the increase in CQI in the frequency dimension is as follows. The previously discussed CQI was specific to one frequency band. If the receiving side selects the frequency band showing the best channel state, transmits only the selected frequency, and the transmitting side performs the service through the frequency band selected by the CQI, the CQI is needed in only one band. Such a case is suitable for a single user environment, but not for a multi-user environment, so a more efficient method is needed. Looking at the problem in the scheduling process when the CQI is transmitted in only one preferred band in more detail as follows. There is no problem if the frequency bands preferred by multiple users are not overlapped with each other. However, a problem occurs when a user selects a specific frequency band as the best channel environment at the same time. In this case, users other than the selected user cannot use the corresponding frequency band. Here, if each user transmits only one preferred frequency band, the users not previously selected are essentially blocked from receiving the service. Therefore, in order to solve this problem and effectively obtain the multi-user diversity gain, CQI transmission for several frequency bands is required. When transmitting CQI corresponding to several frequency bands, the amount of CQI transmission information for the selected frequency band is increased. For example, if three channel bands are selected in order of good channel condition and each CQI and frequency band indicators are transmitted, the transmission amount of the CQI is tripled and additional transmission is performed for the indicator to indicate the selected frequency band. It is necessary.

Third, an increase in CQI can be considered in consideration of both space and frequency. In other words, it is also possible to have several CQIs in the spatial dimension and several CQIs in the frequency dimension.

Fourth, an increase in CQI at other levels is conceivable. For example, when the code division multiple access (CDMA) method is used, the signal strength and the amount of interference occur for each spreading code, and the CQI for each spreading code can be considered. Therefore, an increase in CQI in the code dimension is conceivable. In addition, an increase in CQI at various levels may be considered.

We have seen cases where multiple CQIs are needed at various dimensions. When multiple CQIs are needed, the concept of differential CQI (Delta CQI) can be used to reduce the amount of CQI transmission. That is, by selecting one reference CQI, the reference CQI is transmitted normally, while the other CQIs transmit only the difference from the reference CQI. That is, a method similar to differential modulation in the modulation and demodulation method is used. In this case, when a plurality of CQIs are represented in a differential manner, a large number of bits are generally allocated to the CQI reference value and a relatively small number of bits are allocated to the difference value, thereby reducing the total amount of transmitted CQIs.

Meanwhile, in the next generation mobile communication system, in order to efficiently use a multi-band or a multi-carrier, a plurality of carriers (multiple frequency allocation bands) are assigned to a specific layer above the physical layer. Techniques for managing by one corresponding entity have been proposed.

2 (a) and 2 (b) are diagrams for conceptually explaining a multi-band RF based signal transmission / reception method from a transmitter side and a receiver side.

In (a) and (b) of FIG. 2, PHY0, PHY1, .. PHY n-2, PHY n-1 represent multiple bands according to the present technology, and each band indicates a specific service according to a predetermined frequency policy. It may have a frequency allocation band (FA) size to allocate. For example, PHY0 (RF carrier 0) may have a frequency band size allocated for general FM radio broadcasting, and PHY1 (RF carrier 1) may have a frequency band size allocated for cellular communication. However, the following description focuses on using a combination of several 20 MHz system bands allocated for an existing system, for example, 3GPP LTE system, to secure wider system bandwidth in a next generation mobile communication system such as 3GPP LTE-A. Explain. As described above, each frequency band may have a different frequency band size according to the characteristics of each frequency band. However, in the following description, it is assumed that each frequency allocation band FA has a constant size. As described above, each frequency allocation band avoids confusion with the concept of "Muti-Carrier," which is widely used in a system using a plurality of subcarriers as in the conventional OFDM-based communication scheme, and in a legacy system. In view of using a plurality of system bands, it may be referred to as a "legacy system band". In addition, each legacy system band may be represented by a carrier frequency for using a baseband signal in each frequency band, hereinafter, each frequency allocation band is simply a "carrier frequency band" or simply "carrier" when there is no confusion. It will be referred to as.

In order to transmit a signal through multiple bands as shown in (a) of FIG. 2 and to receive a signal through multiple bands as shown in (b) of FIG. It is required to include. In addition, in FIG. 2, the configuration method of "MAC" is determined by the base station regardless of DL and UL.

In short, the present technology allows one predetermined number of specific layer entities, one MAC entity in the example of FIG. 2 (hereinafter simply referred to as " MAC " when there is no confusion), to manage / multiple RF carriers. It is a technology that operates and transmits and receives signals. In addition, RF carriers managed in a particular entity do not need to be contiguous with each other. Therefore, according to the present technology, there is an advantage of being more flexible in terms of resource management.

For example, assume the following frequency usage.

3 is a diagram illustrating an example of frequency allocation in a multi-band assisted communication scheme.

In FIG. 3, FA0 to FA7 may be managed by RF0 to RF7. In addition, in the example of FIG. 3, it is assumed that FA0, FA2, FA3, FA6 and FA7 are already allocated to the existing specific communication service, respectively. On the other hand, it is assumed that the available RF1 (FA1), RF4 (FA4), RF5 (FA5) can be effectively managed by one MAC (MAC # 5). Here, since the RF carriers constituting one MAC may not be adjacent to each other as described above, it is possible to more effectively manage frequency resources. However, as described above, the MAC managing the plurality of RF carriers may be two or more.

When the channel quality indicator is transmitted in a communication system using a plurality of carriers and a plurality of legacy system bands as described above, an increase in overhead due to the transmission of the channel quality indicator is expected. At present, there is no specific method for transmitting the channel quality indicator in a system using a plurality of carriers, and it is necessary to define a method for efficiently performing this.

An embodiment of the present invention for solving the above problems is to provide a method for efficiently transmitting a channel quality indicator in a system using a plurality of carriers.

In one embodiment of the present invention for solving the above problems, as a method for transmitting a channel quality indicator by the user equipment in a system for performing communication using a plurality of legacy system bands, through the plurality of legacy system bands Receiving a signal; And transmitting channel quality indicators for the plurality of legacy system bands using the same channel quality indicator transmission mode for each legacy system band, wherein the channel quality indicators for each legacy system band are transmitted through an uplink shared channel. When transmitting, when transmitting the entire channel quality indicator for each legacy system band, and transmitting the channel quality indicator for each legacy system band through an uplink control channel, a predetermined number of channel quality indicators for each legacy system band The present invention proposes a channel quality indicator transmission method characterized in that the transmission sequentially in units.

On the other hand, in another embodiment of the present invention for solving the above problems, as a method for transmitting a channel quality indicator by the user equipment in a system for performing communication using a plurality of legacy system bands, the plurality of legacy systems Receiving a signal over a band; And transmitting channel quality indicators for a specific number of legacy system bands preferred among the plurality of legacy system bands, and transmitting channel quality indicators for the specific number of legacy system bands through an uplink shared channel. In this case, the entire channel quality indicator for the specific number of legacy system bands is transmitted, the channel quality indicator for the specific number of legacy system bands is transmitted through an uplink control channel, and the specific number of legacy system bands. When the uplink control channel capacity is insufficient to transmit the entire channel quality indicator for the channel quality indicator transmission method characterized in that for transmitting a predetermined number of channel quality indicators for the specific number of legacy system bands sequentially Suggest.

The channel quality indicator transmission method may further include receiving a control signal for requesting transmission of the channel quality indicator. When the channel quality indicator is transmitted after the control signal is received, the channel quality indicator may include: It may be transmitted through the uplink shared channel.

Further, in a transmission mode in which a wideband channel quality indicator transmission is required among the channel quality indicator transmission modes through the uplink shared channel or the uplink control channel, the wideband channel quality indicator includes a channel quality indicator for each legacy system band. Can be used.

In addition, the method for transmitting a channel quality indicator by selecting a specific number of legacy system bands, the method may further include transmitting information on the preferred number of legacy system bands. In this case, the information about the selected legacy system band may be transmitted in a bitmap format or may directly transmit an index for each legacy system band.

The method for transmitting a channel quality indicator by selecting a specific number of legacy system bands, wherein the channel quality indicator for a legacy system band that is not selected as a preferred number of legacy system bands among the plurality of legacy system bands. The method may further include transmitting, in the form of a broadband channel quality indicator, on a predetermined cycle basis.

According to the channel quality indicator transmission method according to each embodiment of the present invention as described above, it is possible to improve the system performance by setting the performance degradation of the scheduler to a minimum while minimizing overhead in a system using a plurality of legacy system bands. .

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced.

The following detailed description includes specific details in order to provide a thorough understanding of the present invention. However, one of ordinary skill in the art appreciates that the present invention may be practiced without these specific details. In some instances, well-known structures and devices are omitted or shown in block diagram form, centering on the core functions of each structure and device, in order to avoid obscuring the concepts of the present invention. In addition, the same components will be described with the same reference numerals throughout the present specification.

As described above, an embodiment of the present invention proposes a method for efficiently generating and transmitting a CQI in a system for transmitting signals using a plurality of carriers. In a system using multiple carriers, independent control signals may be transmitted for each carrier.

4 shows an example of configuring a broadband system using five carriers.

For example, in FIG. 4, assuming that the 20 MHz band is transmitted on one carrier, 100 MHz can be transmitted using five carriers, and an independent control signal can be transmitted every 20 MHz. Such a system has the advantage that it can be easily implemented by simply extending the control channel designed for a 20 MHz system. However, when considering CQI transmission, since CQI / PMI / RI should be transmitted independently every 20 MHz, the amount of control information increases in proportion to the number of carriers used. In order to transmit this, many resources have to be allocated, which makes it difficult to use system resources efficiently.

In order to efficiently support a scheduling operation, it is required to report channel information of a band corresponding to all carriers. Although the following description can be applied to both downlink and uplink, the CQI transmission method for downlink data transmission will be described as an example.

First, an embodiment of the present invention proposes a method of transmitting all channel information of each carrier. In a system using N carriers, a CQI corresponding to a band of each carrier may be transmitted through an uplink shared channel or an uplink control channel. In the 3GPP LTE system, CQI may be transmitted through PUSCH or PUCCH.

In this embodiment, it is assumed that the CQI generation method used in the system is applied to the entire carrier using only one type. Here, the CQI generation method may be defined differently according to the channel type for CQI transmission, and various CQI transmission modes may exist within each channel.

Hereinafter, various methods that can be used for CQI generation and transmission are described.

As the amount of channel transmission is increased, the following method is possible as a generation method for reducing the amount of information of the channel quality indicator to reduce the waste of such control signals.

First, a method of changing the unit of channel information transmission. For example, in the orthogonal multiple carrier (OFDM), channel information transmitted for each subcarrier is grouped into one subcarrier group, and channel information is transmitted in the corresponding group unit. That is, in the orthogonal multiple carrier method using 600 subcarriers, if 12 subcarriers are collected and formed into one subcarrier group, a total of 50 subcarrier groups are formed, and thus the amount of channel information actually transmitted is reduced from 600 to 50. do.

In the following description, in the case where a frequency band is divided into integers into respective subcarriers, such as an Orthogonal Multiple Carrier System (OFDM), one or more subcarriers are grouped into one group and divided into the subcarrier group units, respectively. The basic unit of the method of reporting the CQI subcarrier group or CQI subband is defined. On the other hand, if the frequency band is not distinguished with each subcarrier, the entire frequency band is divided into some frequency bands, and the CQI is generated based on the divided frequency bands, and the divided frequency bands for the CQI generation are defined as CQI. Define it as a subband.

Secondly, a channel quality indicator is generated by compressing channel information. For example, in an orthogonal multiple carrier scheme, channel information for each subcarrier is compressed and transmitted using a compression scheme. As the compression method, methods such as a discrete cosine transform (DCT) may be considered.

Third, a method of generating a CQI by selecting a corresponding frequency band for generating channel information. For example, in the orthogonal multicarrier method, the best-M method may be selected to transmit the best M of subcarriers or subcarrier groups instead of transmitting channel information for every subcarrier.

When transmitting the CQI which selects and transmits the frequency band, the actual transmitted part can be largely divided into two parts. The first is the CQI value part and the second is the CQI index part.

5 is a diagram illustrating techniques for generating a CQI by selecting a CQI subband in the frequency domain.

The frequency band selective CQI scheme consists of three parts. The first method is to select a frequency band for generating CQI, that is, a CQI subband. Second, a method of generating and transmitting CQI values of the selected frequency bands by manipulating them. Third, a method of transmitting indexes of the selected frequency band, that is, CQI subbands.

In FIG. 5, first, Best-M and Threshold-based methods are used as examples of a method of selecting a CQI subband. The Best-M scheme selects M CQI subbands with good channel conditions. In the example of FIG. 5, the CQI subbands with good channel conditions are selected using the Best-3 scheme. . In addition, the threshold-based method is a technique of selecting a CQI subband having a channel state higher than a predetermined threshold. In this example, the CQI subbands of indexes 5 and 6 higher than the threshold are selected.

On the other hand, as an example of a method for generating and transmitting CQI values, the individual transmission method and the average transmission method are given. The individual transmission scheme is a method of transmitting all CQI values of the CQI subband selected in the first step. Thus, the individual schemes also have more CQI values to transmit as the number of selected CQI subbands increases. Meanwhile, the average transmission method is a method of transmitting an average value of CQI values of the selected CQI subband. Therefore, the average transmission method has the advantage that the CQI value to be transmitted becomes one regardless of the number of the selected CQI subbands, whereas the average transmission method has a disadvantage in that accuracy is reduced. In the average transmission method, the average value may be a simple arithmetic average or may be an average in consideration of channel capacity.

Third, examples of a method of transmitting an index of a CQI subband include a bitmap index method and a general combination index method. Bitmap indexing refers to a method of indicating which CQI subbands are used by allocating one bit for every CQI subband, and assigning 1 if the corresponding CQI subband is used and 0 if not used. do. While the bitmap indexing method requires the number of bits as much as the total CQI subbands, the bitmap indexing scheme can always be represented by a constant number of bits regardless of how many CQI subbands are used.

On the other hand, the combination index method is a method of determining how many CQI subbands are to be used and mapping the number of combinations corresponding to the number of CQI subbands used in the total CQI subbands to each index. In more detail, when there are a total of N CQI subbands and M CQI subbands among the N are used, the total number of possible combinations is as follows.

The number of bits for representing the number in the case of Equation 1 may be determined as follows.

.In the example of FIG. 5, since three CQI subbands are selected from a total of 11 CQI subbands, the number of possible cases is 165 (= ₁₁ C ₃ ), and the number of bits for representing the 165 is 8 bits. to be

.

Meanwhile, the transmission mode that can be used for CQI transmission will be described in more detail as follows.

Scheduling Method Periodic CQI Transmission Aperiodic CQI Transmission Frequency non-selective PUCCH - Frequency selective PUCCH PUSCH

As shown in Table 1, the CQI may be transmitted using a PUCCH (physical uplink control channel) at a period determined by a higher layer, or a PUSCH (physical uplink shared channel) aperiodically according to the needs of a scheduler. May be sent. In the case of transmitting the CQI through the PUSCH, only the frequency selective case is possible.

As described above, the case in which the CQI is transmitted and the case in which the CQI is periodically transmitted will be described.

1) Transmission of CQI / PMI / RI through PUSCH after receiving CQI transmission request control signal

This case is a case where a control signal requesting to transmit a CQI is received. Table 2 below shows modes when transmitting CQI / PMI / RI through a PUSCH.

PMI feedback type PMI not sent Single PMI Multi PMI PUSCH CQI Feedback Type Wideband (Wideband CQI) Mode 1-2 UE Selected (Subband CQI) Mode 2-0 Mode 2-2 Higher Layer-configured (Subband CQI) Mode 3-0 Mode 3-1

The transmission mode of Table 2 is selected in a higher layer, and all CQI / PMI / RI are transmitted through the same PUSCH subframe.

Hereinafter, each transmission mode will be described.

First, "Mode 1-2" selects a precoding matrix for each subband under the assumption that data is transmitted only through the corresponding subband. The UE generates a CQI assuming a precoding matrix previously selected for the entire band (set S) designated by the system band or the higher layer. The terminal transmits the CQI and the PMI value of each subband. At this time, the size of each subband may vary depending on the size of the system band.

Next, in "Mode 2-0", the UE selects the preferred M subbands for the system band or the band designated by the higher layer (set S). The UE generates one CQI value assuming that data is transmitted for the selected M subbands. The terminal further generates one CQI (wideband CQI) value for the system band or set S. When there are a plurality of codewords for the selected M subbands, the CQI value for each codeword is defined in a differential format. In this case, the differential CQI may use a value obtained by subtracting the wideband CQI index from the index corresponding to the CQI values for the selected M subbands. The terminal transmits information about the location of the selected M subbands, one CQI value for the selected M subbands, and a CQI value generated for all bands or a set S. At this time, the size of the subband and the M value may vary depending on the size of the system band.

Next, in "Mode 2-2", the UE simultaneously selects a single precoding matrix for M preferred subbands and M preferred subbands under the assumption that data is transmitted through M preferred subbands. CQI values for M preferred subbands are defined for each codeword. The terminal further generates a wideband CQI value for the system band or set S. In addition, the UE transmits information on the positions of the M preferred subbands, one CQI value for the selected M subbands, a single precoding matrix index for the M preferred subbands, and a wideband CQI value. At this time, the subband size and M value may vary depending on the size of the system band.

In addition, in "Mode 3-0", the UE generates a wideband CQI value. The UE generates a CQI value for each subband assuming that data is transmitted through each subband. At this time, even if RI> 1, the CQI value represents only the CQI value for the first codeword.

Finally, "Mode 3-1" generates a single precoding matrix for the system band or set S. The UE assumes a single precoding matrix generated for each subband and generates subband CQI for each codeword. The terminal also assumes a single precoding matrix and generates a wideband CQI. The CQI value of each subband is expressed in differential form. In addition, the size of the subband may vary depending on the size of the system band.

2) Periodically transmit CQI / PMI / RI through PUCCH

In this case, the CQI information is periodically transmitted through the PUCCH. When a control signal for transmitting user data is received, the CQI may be transmitted through the PUSCH. Although transmitted through the PUSCH, the contents of the CQI / PMI / RI generate and transmit the CQI by one of the transmission modes defined in Table 3 below.

PMI feedback type PMI not sent Single PMI PUCCH CQI Feedback Type Wideband (Wideband CQI) Mode 1-0 Mode 1-1 UE Selected (Subband CQI) Mode 2-0 Mode 2-1

In Table 3, in case of Mode 2-0 and Mode 2-1, a bandwidth part (BP) is a set of subbands consecutively located in the frequency domain and may cover a system band or a set S. The size of each subband, the size of the BP, and the number of BPs may vary depending on the size of the system band. In addition, the CQI is transmitted in the frequency domain in ascending order for each BP so as to cover the system band or the set S. FIG.

In the CQI transmission type, four transmission types exist according to the transmission combination of CQI / PMI / RI as follows.

(1) Type 1: Subband CQI of Mode 2-0 and Mode 2-1 is transmitted.

(2) Type 2: Transmit wideband CQI and PMI.

(3) Type 3: Send RI.

(4) Type 4: Send wideband CQI.

When the RI and the wideband CQI / PMI are transmitted, they are transmitted in subframes having different periods and offsets. When the RI and the wideband CQI / PMI are transmitted in the same subframe, the CQI / PMI is not transmitted.

Among the transmission schemes, the wideband CQI / PMI and subband CQI transmission periods are P and have the following characteristics.

Wideband CQI / PMI has a period of H * P. At this time, H = J * K + 1, J is the number of bandwidth parts (BP), and K is the total number of cycles of the BP. That is, wideband CQI / PMI transmits at {0, H, 2H, ...}. In addition, a J * K time point other than a time point of transmitting wideband CQI / PMI transmits a subband CQI.

The transmission period of the RI is M times the wideband CQI / PMI period and has the following characteristics.

The offset between RI and wideband CQI / PMI is O. When RI and wideband CQI / PMI are transmitted in the same subframe, wideband CQI / PMI is not transmitted. The above parameters P, H, K, and O are all determined at higher layers and signaled.

Meanwhile, each transmission mode shown in Table 3 will be described below.

First, when the RI is transmitted in "Mode 1-0", the RI is generated for the system band or the set S and transmitted through the Type 3 report. In case of transmitting the CQI, the wideband CQI is transmitted.

Next, when transmitting the RI in "Mode 1-1", the RI is generated for the system band or set S, and a type 3 report is transmitted. In case of transmitting CQI / PMI, a single precoding matrix is selected based on the most recently transmitted RI. Send a Type 2 report consisting of wideband CQI, single precoding matrix, and differential wideband CQI.

Next, when transmitting the RI in "Mode 2-0", the RI is generated for the system band or set S, and the Type 3 report is transmitted. In case of transmitting a wideband CQI, a wideband CQI is generated assuming the most recently transmitted RI and a type 4 report is transmitted. When transmitting the CQI for the selected subband, the UE selects the most preferred subband for J BPs composed of N subbands and transmits a Type 1 report. Type 1 reporting may require one or more subframes depending on the BP.

Finally, when transmitting the RI in "Mode 2-1", generate an RI for the system band or set S, and send a type 3 report. In case of transmitting a wideband CQI, a wideband CQI is generated assuming the most recently transmitted RI and a type 4 report is transmitted. When the CQIs for the selected subbands are transmitted, the UE assumes the most recently transmitted PMI / RI for the N j BPs, and the single CQI value for the selected subbands in the BP and RI is 1 If larger, assuming that a single precoding matrix is used for the most recently transmitted RI and the selected subband, CQI differences of codewords are generated and transmitted using Type 1 reporting.

Each CQI transmission mode and type described above may be referred to differently according to a system, and may be represented using other terms as long as the names of the aforementioned transmission modes indicate the same / similar transmission modes.

Among these various CQI transmission methods, the CQI transmission method used in this embodiment proposes to transmit each CQI for all carrier bands using the same transmission scheme for each carrier band. For example, if the CQI is generated using Mode1-2 in the CQI transmission mode for PUSCH on the first carrier, it is assumed that Mode 1-2 is used in the CQI transmission mode for PUSCH in all other carriers. Here, the CQI generation method may be differently defined for the method for transmitting the CQI and the method for periodically transmitting the CQI after receiving the CQI transmission request.

In the following description, for convenience of notation, when the CQI corresponding to the j th carrier is CQI _j , the CQI of the system corresponding to the N carriers will be described as {CQI ₁ , .., CQI _N }.

First, a case in which a CQI transmission request control signal is received and then transmitted using a PUSCH will be described.

In the present embodiment, each carrier corresponds to each carrier using a specific CQI generation method selected from Mode 1-2, Mode 2-0, Mode 2-2, Mode 3-0, and Mode 3-1, which are CQI transmission modes through PUSCH. After generating the CQI, it is proposed to collect and transmit all the CQIs of the systems corresponding to all carriers using the PUSCH. In this case, the wideband CQI / PMI is a CQI / PMI value corresponding to the band of the carrier. The RI may be a value corresponding to the carrier band or may be a value corresponding to the entire carrier band.

Next, a case in which the CQI is periodically transmitted using the PUCCH will be described.

In the present embodiment, the CQI corresponding to each carrier is generated using a CQI generation method selected from Mode 1-0, Mode 1-1, Mode 2-0, and Mode 2-1, which are CQI transmission modes through PUCCH, and then collected. To generate the CQI of the system corresponding to the entire carrier. However, when the CQI is transmitted using the PUCCH, it may not be able to transmit all the CQIs at once because the amount of CQIs that can be transmitted at one transmission time is limited. Therefore, in this embodiment, it can be set so that the CQI of each carrier may be transmitted in order. That is, with respect to the entire CQI of {CQI ₁ , ..., CQI _N }, each CQI may be sequentially transmitted from CQI ₁ at each transmission time. At this time, the transmission of CQI _j (j = 1, ..., N) may follow the transmission method of Mode 1-0, Mode 1-1, Mode 2-0, and Mode 2-1.

Meanwhile, another embodiment of the present invention proposes a method of transmitting a CQI by selecting a preferred specific carrier band among a plurality of carrier bands.

That is, in the case of a system using N carriers, it is desirable to secure a CQI corresponding to the entire carrier band for scheduling. However, in order to transmit this, resources must be allocated in proportion to the number of carriers. In order to reduce this, if some preferred carrier bands are selected and CQIs corresponding to the selected carrier bands are transmitted, resources for transmitting control signals can be efficiently used. That is, it is proposed to transmit information on L carriers, {CQI _b1 , .., CQI _bL }, among the preferred CQI, {CQI ₁ , ..., CQI _N }. In this case, it is assumed that N is greater than or equal to bL.

On the other hand, in the CQI transmission method according to the present embodiment, it is proposed to define the CQI transmission method as follows according to whether to transmit the CQI after receiving the control signal for the CQI transmission request.

First, a method of transmitting using PUSCH after receiving the CQI transmission request control signal will be described. The CQIs for the selected L carrier bands, i.e., {CQI _b1 , ..., CQI _bL }, are all transmitted at one transmission time through the PUSCH. In this case, generation of a wideband CQI / PMI means a CQI / PMI value corresponding only to a band of each selected carrier.

On the other hand, the CQI for the carrier band (s) other than the selected L carriers is basically not transmitted, but it is possible to partially transmit the CQI information for the band corresponding to the carrier not additionally selected. In this case, it is proposed to transmit a wideband CQI / PMI value as the partial CQI information.

RI may be a value corresponding to a corresponding carrier band or a value corresponding to an entire carrier band. At this time, the transmission of CQI _j (j = b1, ..., bL) is one of the PUSCH transmission mode Mode 1-2, Mode 2-0, Mode 2-2, Mode 3-0, Mode 3-1 Can be selected and used.

Next, a method of periodically transmitting the CQI using the PUCCH will be described.

CQI, {CQI _b1 , ..., CQI _bL } for the selected L carriers are transmitted through the PUCCH. In this case, transmission of CQI _j (j = b1, ..., bL) may be selected from one of Mode 1-0, Mode 1-1, Mode 2-0, and Mode 2-1, which are PUCCH transmission modes. .

In this embodiment, the CQI for the carrier band (s) other than the selected L carriers is basically not transmitted. However, it is necessary to partially transmit the CQI information for the band corresponding to the carrier not additionally selected. It is possible. In this case, it is proposed to transmit a wideband CQI / PMI value as the partial CQI information.

When transmitting the CQI using the PUCCH, it may not be possible to transmit all the information of the selected carrier band CQI at once because the amount of CQI that can be transmitted at a time of transmission is limited. As described above, when all CQIs cannot be transmitted at once, the CQIs are divided and transmitted several times. At this time, the positions of the first selected L carriers are fixed without changing during the time of dividing the entire CQI.

For example, the CQI of the selected carrier may be sequentially transmitted. That is, for {CQI _b1 , ..., CQI _bL }, it is proposed to sequentially transmit from CQI _b1 . In addition, information on the location of the selected carrier may be additionally transmitted.

As another example, a method of transmitting CQIs of selected carriers evenly divided over several hours may be considered. That is, a portion of each CQI may be transmitted for each time for {CQI _b1 , ..., CQI _bL }.

The detailed description of the preferred embodiments of the invention disclosed as described above is provided to enable any person skilled in the art to make and practice the invention. Although the above has been described with reference to the preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The channel quality indicator transmission method according to each embodiment of the present invention as described above can be applied to various next generation mobile communication systems using a plurality of carrier bands (plural legacy system bands).

1 is a conceptual diagram of CQI generation and transmission.

2 (a) and 2 (b) are diagrams for conceptually explaining a multi-band RF based signal transmission / reception method from a transmitter side and a receiver side.

3 is a diagram illustrating an example of frequency allocation in a multi-band assisted communication scheme.

4 shows an example of configuring a broadband system using five carriers.

5 is a diagram illustrating techniques for generating a CQI by selecting a CQI subband in the frequency domain.

Claims (8)

In a method for transmitting a channel quality indicator by a user equipment in a system for communicating using a plurality of legacy system bands, Receiving a signal over the plurality of legacy system bands; And Transmitting channel quality indicators for the plurality of legacy system bands by using the same channel quality indicator transmission mode for each legacy system band, When the channel quality indicator for each legacy system band is transmitted through an uplink shared channel, the entire channel quality indicator for each legacy system band is transmitted, and the channel quality indicator for each legacy system band is transmitted through an uplink control channel. When transmitting, the channel quality indicator transmission method characterized in that for transmitting the channel quality indicator for each legacy system band in a predetermined number unit. The method of claim 1, Receiving a control signal requesting transmission of the channel quality indicator, And transmitting the channel quality indicator after receiving the control signal, wherein the channel quality indicator is transmitted through the uplink shared channel. The method of claim 1, In a transmission mode in which a wideband channel quality indicator transmission is required among the channel quality indicator transmission modes through the uplink shared channel or the uplink control channel, a channel quality indicator for each legacy system band is used as the wideband channel quality indicator. Channel quality indicator transmission method. In a method for transmitting a channel quality indicator by a user equipment in a system for communicating using a plurality of legacy system bands, Receiving a signal over the plurality of legacy system bands; And Transmitting channel quality indicators for a preferred number of legacy system bands of the plurality of legacy system bands, When the channel quality indicators for the specific number of legacy system bands are transmitted through an uplink shared channel, the entire channel quality indicators for the specific number of legacy system bands are transmitted. When the channel quality indicator for the specific number of legacy system bands is transmitted through an uplink control channel, and the uplink control channel capacity is insufficient to transmit the entire channel quality indicator for the specific number of legacy system bands, And transmitting channel quality indicators for a specific number of legacy system bands in a predetermined number of units. The method of claim 4, wherein And transmitting information on a preferred number of legacy system bands of the plurality of legacy system bands in a direct or bitmap form. The method of claim 4, wherein And transmitting a channel quality indicator for a legacy system band that is not selected as a preferred number of legacy system bands among the plurality of legacy system bands in a predetermined cycle unit in the form of a broadband channel quality indicator. Way. The method of claim 4, wherein Receiving a control signal requesting transmission of the channel quality indicator, And transmitting the channel quality indicator after receiving the control signal, wherein the channel quality indicator is transmitted through the uplink shared channel. The method according to claim 4 or 6, In a transmission mode in which a wideband channel quality indicator transmission is required among the channel quality indicator transmission modes through the uplink shared channel or the uplink control channel, a channel quality indicator for each legacy system band is used as the wideband channel quality indicator. Channel quality indicator transmission method.

Images