KR20070107573A - Method of transmitting and receiving data using discrete cosine transform - Google Patents

Abstract

A method for transceiving data by using DCT(Discrete Cosine Transform) is provided to use limited wireless resources by minimizing a size of transmission information which will be transmitted to a receiving party and transmitting the information of the minimized size. A method for transceiving data by using DCT(Discrete Cosine Transform) comprises the following steps of: performing DCT with respect to first data corresponding to information which will be transmitted to a receiving party; performing data processing after selecting a part of the converted result; and transmitting the data processing result to the receiving party. The method further comprises a step of generating the first data by adjusting a size of second data generated in a transmitting party.

Description

Method of transmitting and receiving data using Discrete Cosine Transform}

1 is a diagram showing the flow of data processing for transmission information transmitted to a receiving side according to this embodiment.

2 is a view for explaining an example of a method for inserting additional information.

3 is a diagram of a method of determining information of bits to be inserted according to the present embodiment.

4 is a diagram illustrating an example of performing data puncturing according to the present embodiment.

5 is a diagram illustrating a first quantization and compression method according to the present embodiment.

6 is a view for explaining a second quantization and compression method according to the present embodiment.

7 is a diagram illustrating a third quantization and compression method according to the present embodiment.

8 and 9 are diagrams illustrating a method of sequentially transmitting a specific number of information constituting channel quality information according to an embodiment of the present invention.

FIG. 10 illustrates a method of measuring channel quality information every time unit, selecting a portion of the channel quality information, and transmitting the selected portion to the receiver.

11 to 14 are diagrams illustrating respective embodiments of a method for transmitting a change amount of channel quality information of a reference unit time and subsequent channel quality information of a unit time according to an embodiment of the present invention.

15 is an example of a mobile terminal to which the present invention can be applied.

The present invention relates to a data transmission method in a mobile communication system, and more particularly, to a data transmission method for minimizing a transmission amount by performing data processing on information to be transmitted.

Conventionally, a method of minimizing the amount of information transmission has been proposed in various technical fields. For example, various methods have been proposed in order to reduce overhead due to control information in a method of transmitting channel quality information (CQI). Hereinafter, a data processing method proposed in the related art to reduce the amount of information transmission will be described.

The mobile communication system maximizes the capacity of the channel. In addition, mobile communication systems use link adaptation in order to maximize channel capacity and efficiently transmit data to users. In order to perform the link adaptation at the base station, the user must feed back channel quality information to the base station. In a multi-carrier system, channel quality is different for each frequency band in which data is transmitted. Therefore, the user sends channel quality information for all frequency bands for efficient resource allocation. That is, the user divides the entire frequency band into several unit frequency bands and sends channel quality information for each unit frequency band. For example, assuming a unit frequency band of 375 kHz in a multi-carrier system having a 20 MHz frequency band and each channel quality information is 5 bits, the amount of information to be fed back each time is 5 x 48 = 240 bits. When there is a plurality of users in one base station, and this information is fed back for each user, a control overhead for efficiently allocating resources increases drastically.

In the past, various methods have been proposed to prevent the sudden increase in the control overhead described above. First, a method of transmitting channel quality information of several best frequency bands by measuring channel quality for each unit frequency band has been proposed. Second, a method of transmitting only one average channel quality information by combining several frequency bands has been proposed. Third, there is a method of reducing the length of the channel quality information itself.

As a representative example of the third method described above, there is a method using a discrete cosine transform (DCT). In order to reduce the length of the channel quality information, the prior art minimizes the amount of channel quality information by using quantization and run-length coding after DCT conversion of the channel quality information.

The present invention has been proposed to improve the above-described prior art, and an object of the present invention is to propose a data processing method for minimizing a transmission amount of information transmitted to a receiving side.

Another object of the present invention is to propose a channel quality information transmission method that solves the problem of increased overhead caused by the transmission of channel quality information.

The communication method according to the present invention relates to a method for transmitting data using a plurality of subcarriers, the method comprising: performing a discrete cosine transform on first data corresponding to information transmitted to a receiving side; Selecting a part of the converted result to perform data processing and transmitting the data processing result to a receiving side.

The method may further include generating the first data by adjusting the size of the second data generated at the transmitter, wherein the first data inserts some bits or pops some bits with respect to the second data. It can be produced by punching. In this case, the communication method of the present invention may further include transmitting control information regarding the inserted or punctured bits.

The data processing may include selecting data of some of the DCT-converted first data and quantizing the selected data. Specifically, the method may include selecting data having an absolute value greater than or equal to a predetermined size among the DCT-converted first data and quantizing the selected data and an index of the data, or performing DCT-converted first data. Selecting some of the data, reselecting the data having an absolute value of a predetermined size or more of the selected data, and quantizing the reselected data and the index of the data.

In this case, the method may further include transmitting control information regarding the selected data from the converted result to the receiving side.

In the data transmission step, when the first data is generated every unit time, the data processing result may be transmitted to the receiving side every unit time, grouping the quantized data into a predetermined unit and And transmitting the grouped data in unit time.

The transmitting of the data may include grouping the quantized first data to include at least one data and an index thereof, and transmitting the grouped data in unit time. When the first data is generated every unit time, grouping the quantized first data to include at least one data and an index thereof for each unit time, and corresponding to the corresponding unit time among the quantized first data. And transmitting the group data to the receiving side.

The data transmission step may include: a reference data transmission step of transmitting the first data processed at an initial unit time to a receiving side when the first data is generated every unit time; And a variable data transmission step of transmitting a difference value between the one data and the reference data to a receiving side.

On the other hand, the communication method according to the present invention, in a method for receiving data using a plurality of sub-carriers, the step of receiving data corresponding to a part of the entire bit string transmitted from the transmitting side in a specific unit of time; Restoring the entire bit string by performing data processing on a part of the bit string; And performing an Inverse Discrete Cosine Transform on the restored data.

In addition, the mobile terminal according to the present invention, in the mobile terminal for transmitting and receiving data using a plurality of subcarriers, the discrete cosine transform (DCT) for the first data corresponding to the information transmitted to the receiving side A DCT module for performing; A data processing module for performing data processing by selecting a part of the output of the DCT module, and a wireless module for transmitting the results of the data processing module to the receiving side.

In addition, the communication system according to the present invention is a mobile communication system for transmitting and receiving data using a plurality of subcarriers, comprising: a wireless module for receiving data corresponding to a part of the entire bit string transmitted by a mobile terminal on a specific time unit; A data processing module configured to recover the entire bit string by performing data processing on the received bit string; And an IDCT module for performing an Inverse Discrete Cosine Transform (IDCT) on the restored data.

The present invention is a data processing method for transmitting as little feedback information as possible in order to overcome the limitation of the transmission capacity of a physical channel. The present invention performs a discrete cosine transform (DCT) on the data transmitted to the receiver, and transmits a DCT coefficient obtained through the transform to the receiver. In this case, it is preferable to transmit only a part of the information on the overall DCT coefficients, thereby minimizing the overhead of feedback information transmitted on the physical channel. In addition, the channel quality information can be fed back according to the channel change rate, and as a result, the scheduling gain of the frequency domain can be increased.

The present invention performs discrete cosine transform (DCT) to compress the information. The data processing method according to the present invention is a data processing method in which the input / output length can be changed flexibly according to the needs of the system. Specifically, compression and information decomposition are performed on the result of performing the discrete cosine transform (DCT).

Preferably, the method according to the present invention is applied to a mobile communication system requiring feedback of downlink channel quality information.

The present invention is a method of feedback after performing a series of signal processing processes based on Discrete Cosine Transform (DCT) technique, and as a result, it is possible to reduce the amount of feedback information and improve the accuracy of feedback information.

Preferably, the data processing method according to the present invention adjusts the discrete cosine transform (DCT) technique after adjusting the length of data to be transmitted to the receiving side. In addition, in the data processing method according to the present invention, it is preferable to perform information compression after a discrete cosine transform (DCT) and to perform quantization. In addition, the data processing method according to the present invention can decompress and transmit the compressed result.

Specific operations, features, and effects of the present invention will be embodied by one embodiment of the present invention described below. Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention.

1 is a diagram showing the flow of data processing for transmission information transmitted to a receiving side according to this embodiment.

As shown, the transmitter adjusts the length of the transmission information, performs DCT, compresses the result value of the DCT, decompresses the compressed information, and transmits it to the receiver. The receiving side performs the data processing performed by the transmitting side in reverse to recover the transmission information. That is, the disassembled transmission information may be assembled according to the disassembly method used by the transmitter, reverse compression of the assembled information, IDCT, and reverse length adjustment may be performed to restore the transmission information.

The transmitting side according to the present embodiment may be a mobile station or a base station, and the receiving side may also be a mobile station or a base station. The transmitting side and the receiving side may transmit and receive data using a plurality of subcarriers orthogonal to each other. That is, the transceiver may transmit and receive data using conventional methods such as orthogonal frequency division multiplexing (OFDM), orthogonal frequency division multiplex access (OFDMA), single carrier-frequency division multiple access (SC-FDMA), and the like.

There is no limitation on the type of the transmission information. The transmission information may be user data to be transmitted to the receiver or control information. Hereinafter, a case in which the transmission information is channel quality information will be described for convenience of description. In the case of the channel quality information, a problem arises that the amount of information increases as the bandwidth between the transmitting and receiving sides increases, so that a technique for minimizing the amount of information is essential. The channel quality information may be information about channel quality for uplink or may be information about channel quality for downlink. Hereinafter, a case of transmitting channel quality information regarding downlink will be described for convenience of description. That is, the transmitting side becomes a mobile station, and the receiving side becomes a base station or a wireless network including a base station. As described above, since there is no limitation on the type of the transmission information, the present invention is not limited to the specific example described below.

In summary, the method according to FIG. 1 may be used as a method for reducing the amount of feedback information when feedback of downlink channel quality information measured in a multicarrier system. When the transmission information is downlink channel quality information, A = {A ₁ , A ₂ , A ₃ ,. , A _Nrb } represents radio link channel quality information, and N _rb represents the length of channel quality information. The length adjusting block 110 of FIG. 1 is a block for adjusting the size of input data in order to efficiently perform DCT. The output of the length adjustment block 110 is indicated by B. That is, the NL value for the output of the length adjusting block 110 represents the adjusted data length and the output is expressed as B (= {B ₁ , B ₂ , B ₃ ,..., B _NL }).

The output of the length adjusting block 110 is input to the DCT module 120. The DCT module 120 performs a DCT operation, and the DCT operation is known to decrease the most when the power of two squared. The size of the output of the length adjusting block 110 is any number free, but preferably may be the number of powers of two. That is, the input length of the appropriate DCT can be input as required by the system.

As shown in FIG. 1, when a DCT operation is performed by the DCT module 120, NL output values {C ₁ , C ₂ , C ₃ ,... , C _NL } is generated. The output value undergoes various post-processing processes according to the system environment.

As a representative example of the above-described post-processing process, there is a quantization and compression process for reducing the amount of information as shown in FIG. That is, quantization and compression are performed by the DCT information compression module 130 to which the output of the DCT module 120 is input. When the quantization and compression process is performed, NC output values {D ₁ , D ₂ , D ₃ ,... , D _NC }, and these values can be used as feedback information and sent to the receiver. However, the output of the DCT information compression module 130 may be decomposed by a specific method by the information decomposition module 140 without transmitting the output at a time.

The receiving side, for example, the base station receives the information fed back from the transmitting side, performs the assembly / combining process, and sequentially performs a process opposite to a series of processes in the mobile station to restore the channel quality information. That is, as described above, the mobile station can feed back one meaningful feedback information (N _C information) at once or divide it into appropriate sizes (N _B information) with a time difference. In case of received information with time difference, an assembly process is required to perform IDCT. Since the channel quality information can be transmitted in various forms, these rules should be set in advance or notified as necessary. The assembly process is preferably performed by the information assembly module 150 provided on the receiving side. The output of the information assembly module 150 is input to the DCT information decompression module 160 which performs the operation of the DCT information compression module 130 in reverse. The signal estimated and reconstructed by the DCT information decompression module 160 is input to an inverse DCT module 170 and reconstructed into NL data. The output of the inverse DCT module 170 is input to the inverse length adjustment block 180 which performs the operation of the length adjustment block 110 in reverse and is output as transmission information.

Hereinafter, specific operations of each block and module provided in the transmission and reception side will be described.

Hereinafter, the operation of the length adjusting block 110 for adjusting the length of the transmission information generated at the transmitting side will be described.

If the length of the channel quality information (N _rb ) and the length (NL) required at the desired DCT input terminal do not match, it is necessary to adjust the N _rb value (for example, to remove or insert a specific bit) for efficient processing of the DCT. There can be. If N _rb = N _L, then {A ₁ , A ₂ , A ₃ ,. , A _Nrb } and {B ₁ , B ₂ , B _{3 ,.} , B _NL } can be equal. In this case, the length adjusting block 110 may not perform any operation or may be omitted. In addition, the length adjustment block 110 may adjust and output the order of the channel quality information generated according to a specific rule. In this case, {B ₁ , B ₂ , B ₃ ,... , B _NL } is generated.

In this embodiment, two types of length adjustment methods are proposed. Hereinafter, the case where N _rb <N _L will be described.

If N _L is greater than N _rb then the original signals {A ₁ , A ₂ , A ₃ ,. , A _Nrb } in the specified region {X ₁ , X ₂ ,... , X _NL-Nrb } is inserted in various ways to maintain the same length as NL. In this case, the inserted position may be transmitted to the receiving side by various methods. That is, if it is determined according to a predetermined pattern, separate control information is not transmitted to the receiving side. If the transmitting side (mobile station) arbitrarily designates a position, it indicates the position of the inserted bit or the rule to be inserted. Additional control information about the insertion pattern may be transmitted together with the feedback information. The control information may be transmitted together with feedback information, transmitted through a physical layer channel, or transmitted using MAC signaling. That is, control information may be transmitted to the receiving side through the first layer or the second layer.

2 is a view for explaining an example of a method for inserting additional information. 2 illustrates a bit into which additional four bits (x ₁ , x ₂ , x ₃ , x ₄ ) are inserted. As shown in FIG. 2A, the inserted bits may be inserted at the end of N _rb bit strings. Also, as shown in FIG. 2 (b), the bits to be inserted may be inserted at the beginning of the N _rb bit strings. In addition, as illustrated in FIG. 2C, bits to be inserted may be inserted at predetermined positions of the N _rb bit strings. It may also be inserted at regular intervals as shown or at irregular intervals as shown in FIG.

Hereinafter, the contents of the additionally inserted bits will be described. Information to be inserted X = {X ₁ , X ₂ ,... , X _NL-Nrb } possible examples may be as follows.

First, the bits to be inserted may have a value of zero or a certain size. The inserted bit may be an average value of channel quality information included in a specific bit string. In addition, the inserted bit may be a copy of the channel quality information at a specific bit position. In addition, the inserted bit may be an interpolation value according to a specific bit string. The inserted value may also follow a rule preset at the transmitting and receiving end, or may follow a rule that varies variably according to a transmitting side. If the size of the inserted value varies variably, the control information on the pattern of the inserted value may be included in the channel quality information and transmitted, or may be separately transmitted through signaling of the first layer or the second layer.

3 is a diagram of a method of determining information of bits to be inserted according to the present embodiment. 3 illustrates a bit into which additional four bits (x ₀ , x ₁ , x ₂ , x ₃ ) are inserted. As shown in FIG. 3A, the inserted bits may be an average value of a bit string consisting of N _rb (ie, 12) bits. In addition, as illustrated in FIG. 3B, the inserted bit may be a copy of a bit at a specific position among N _rb bit strings. 3 (b) shows an example in which the bits of the first four bits are copied and inserted. 3 (c) shows an example of determining the insertion bit with copies of h ₈ , h ₉ , h ₁₀ , and h ₁₁ . 3 (d) shows an example in which four bit values to be inserted are determined by interpolation. The four bit values are determined through interpolation over all or some of the bits of N _rb bits.

2 to 3 illustrate an example of inserting four bits into a 12-bit information string. In addition, a method of determining an insertion bit by obtaining an average value for specific bits or generating a copy of specific bits has been described. The size of the above-described bits or the positions of the bits are merely examples for convenience of description, and the present invention is not limited to these specific numerical values.

Hereinafter, the case where N _rb > N _L will be described. When N _rb > N _L , channel quality information A = {A ₁ , A ₂ , A ₃ ,. , A _Nrb } is puncturing N _rb -N _L values to make the total length equal to N _L. In this case, a predetermined puncturing pattern may be used or a puncturing method may be arbitrarily used. In the case of puncturing arbitrarily, relevant location information should be additionally transmitted. Control information on the puncturing pattern should be transmitted. Control information according to the present embodiment may be included together in transmission information and transmitted together, or may be separately transmitted through signaling of a physical layer or a higher layer. That is, the related location information includes all methods of transmitting together with channel quality information or separately transmitting through L1 (Layer 1) / L2 (Layer 2) signaling.

4 is a diagram illustrating an example of performing data puncturing according to the present embodiment. As shown, certain data bits h ₁ , h ₄ , h ₇ , and h ₁₀ of 12 bits of information are punctured and not transmitted.

The reverse length adjustment block 180 according to the present embodiment reverses the operation of the length adjustment block 110. That is, when specific bits are inserted at the transmitting side, the inserted bits may be removed according to control information or preset patterns for the insertion bits. In addition, when specific bits are punctured at the transmitting side, the length of the bit string may be restored using control information or a predetermined pattern for the flattened bits.

Hereinafter, the operation in the DCT information compression module 130 will be described. The DCT information compression module 130 compresses the channel quality information. That is, information compression on the output value C of the DCT module 120 is performed.

In this embodiment, the output value C = {C ₁ , C ₂ , C ₃ ,... Of the DCT module 120. In order to reduce the amount of information, C _NL }, we propose three quantization and compression processes. The first method is a DCT Lowest M technique that transmits M DCT coefficients corresponding to the smallest DCT index. The second method is DCT Significant M, which transmits only the most meaningful DCT coefficients. The third method is a DCT Hybrid NM technique using a combination of the first technique and the second technique. The DCT coefficients obtained from the three proposed schemes may be transmitted all at once or may be transmitted in several time intervals according to a defined distribution rule.

Hereinafter, the DCT Lowest M technique, which is the first of three quantization and compression methods, according to the present embodiment will be described.

DCT Lowest M method uses DCT result {C ₁ , C ₂ , C ₃ ,. , C _NL } takes only the M information with the lowest index number and returns it. Due to the inherent nature of the DCT, the result of the DCT is that the DCT corresponding to the small index has a meaningful value. In this embodiment, only the M information having the lowest index number is transmitted using the characteristics of the DCT. That is, N _C in FIG. 1 becomes M, and {C ₁ , C ₂ , C ₃ ,... , C _M } is {D ₁ , D ₂ , D ₃ ,. , D _NC }.

5 is a diagram illustrating a first quantization and compression method according to the present embodiment. As shown, there are DCT result values for indices of 1 to 32. The example of FIG. 5 proposes to transmit only DCT results for indices of 1 to M. In other words, the DCT result for the index of M + 1 is ignored. 5 is an example in the case of M = 7. That is, the DCT result for the index of 1 to 7 is transmitted.

The variable M is based on using a fixed value in order to minimize the amount of control information. That is, M may be fixed. However, the M value can be transmitted while changing from time to time according to channel state change, control channel capacity, terminal capability and QoS policy. That is, M may be variable. In the case of using a variable M value, when the M value changes, the changed information must be properly conveyed. The M value may directly indicate the number of specific indexes or may indicate a predetermined index level. For example, M may be set to one of 5, 7, 10, and 15 values. In this case, the M value can be represented through 2 bits of control information. At this time, if the M value is set to several levels, the amount of additional control information can be reduced. As described above, the control information transmission method according to the present embodiment includes a method of transmitting control information such as channel quality information (i.e., transmission information), a method of transmitting by separate signaling through a physical channel, and MAC signaling. It includes all methods of transmitting control information through layer messages.

Meanwhile, according to the importance of the DCT coefficient according to the index, the number of quantization bits expressing the index may be set differently.

5 is an example of transmitting only DCT results corresponding to the indices of 1 to 7, and quantization is applied to DCT results corresponding to the indices of 1 to 7. As shown, the DCT results are displayed in units of 0.5 and transmitted. That is, the result of FIG. 5 is an example of displaying the DCT result at nine levels. There is no limitation on the type of quantization applied according to this embodiment. For example, quantization can be applied at many levels for a specific index, and quantization can be applied at a small level for the remaining indexes. For example, if necessary, the number of bits representing C ₁ and the number of bits representing C ₂ may be set differently. Applying the above quantization, there is an advantage that can transmit a more accurate DCT result for a particular index.

Hereinafter, the DCT Significant M technique, which is the second of three quantization and compression methods, according to the present embodiment will be described.

The DCT Significant M scheme according to the present embodiment is a compression scheme that takes M DCT results determined to be most meaningful at the transmitting side, i.e., the mobile station. Here, the method of selecting the most meaningful information is the first method of selecting M information having the largest absolute value, and the second method of selecting M information having the largest absolute value after applying different weights according to the index. Do. Since the first selection method selects meaningful information according to the absolute value of the DCT result, M results are selected in order of the absolute value of the DCT result. The second selection method is a method of selecting meaningful information in consideration of the absolute value of the DCT result and its index. For example, when a large weight is applied to a specific index, the specific index is more likely to be selected as meaningful information.

In the DCT Significant M method, since the location and value of meaningful information are not fixed, the corresponding information should be transmitted to the base station. That is, it should be transmitted including the position L for the M pieces of information selected in the bit string C. Thus, the signal D = {D ₁ , D ₂ , D ₃ ,... , D _NC } gives the signal C = {C ₁ , C ₂ , C ₃ ,. , C _NL } is made by combining the location information L added to the M pieces of information selected.

Location information added at this time L = {L ₁ L ₂ L ₃ ... L _k } can be configured in two ways.

In the first method, {C ₁ , C ₂ , C ₃ ,... , C _NL } to form a signal by placing each position information (L _i ) adjacent to individual information (C _i ) selected from M or less than M (if some of the selected signals do not need position information). Way. For example, assuming that the signal length is 64, M is 7 (7 is selected and transmitted), and C ₁ of a specific location is always transmitted after DCT, M-1 = 6 is required. Information. The six pieces of location information are transmitted by separately expressing the location information of this information.

In summary, the first method always sends the result for a particular index and this rule is preset. For example, C ₁ corresponding to index ₁ is always transmitted, so no separate location information is needed. However, since the DCT result corresponding to the remaining indexes must be transmitted at an additional rate, location information is transmitted. However, separate location information and transmit it. That is, location information is separated and transmitted in units of DCT results. Since there is no limit on the number of DCT results transmitted and the number of DCT results transmitted at all times, a plurality of DCT results having various indices may always be transmitted.

In the second method, {C ₁ , C ₂ , C ₃ ,... , C _NL } represents a position pattern combination of C _i values that can be taken as one position information L.

For example, after performing DCT, the DCT result exists for indexes 1 to 64, M is determined to be 7 (7 selected and transmitted), and the DCT result for index 1 is always transmitted. The location information required by the is 6 (= M-1) pieces of information. At this time, the type of the position pattern, that is, the number of cases of the information requiring the position information among the total information is ₆₃ C ₆ . Therefore, 27 (= log ₂ ( ₆₃ C ₆ )) bits are required to indicate the location of the selected information. This value is expressed as a single L value and transmitted. That is, it is possible to accurately convey which DCT result is selected as meaningful information through the location information composed of 27 bits.

6 is a view for explaining a second quantization and compression method according to the present embodiment. In FIG. 6, {D ₁ , D ₂ , D ₃ ,..., Output signals of the DCT information compression module 130. , D _NC } means either a DCT result or location information (ie, index information for a DCT result selected as meaningful information).

As shown in FIG. 6, the result of DCT is for indices of 1 to 64. In the example of FIG. 6, index 1 is always determined as meaningful information, and the remaining six meaningful information are determined. As described above, there are two methods for determining the meaningful information, and the determined meaningful information is quantized and then transmitted to the receiver. However, as described above, since the index for the meaningful information is variable, it is necessary to inform the receiving side of 6 indexes selected from 63 indexes. In other words, control information about an index of meaningful information should be transmitted. The control information is included in the channel quality information and transmitted through a physical channel, or may be transmitted to a receiver through separate first layer signaling or separate second layer signaling. Method 1 and Method 2 of FIG. 6 are examples of including the control information in the channel quality information and transmitting the same through the physical channel. As described above, Method 1 is a method of separating and transmitting an index for a DCT result determined as meaningful information, and Method 2 is a method of representing and transmitting 6 meaningful information with one value. Since the number, order, and position of the bits used in the example of FIG. 6 are used for convenience of description, the present invention is not limited by the order of the specific numerical values, bit positions, and indices used in the example of FIG. 6.

Hereinafter, a DCT Hybrid N-M technique, which is the third of three quantization and compression methods, according to the present embodiment will be described.

The DCT Hybrid N-M method transmits a DCT result belonging to a specific section among all DCT results, but quantizes and transmits a DCT result determined by meaningful information among the DCT results belonging to the specific section. By using the DCT Hybrid N-M method, since the number of location information patterns to be expressed is reduced, the number of bits required for location information transmission can be reduced. The number of indexes belonging to the specific section may be referred to as N, and the number of meaningful information may be referred to as M.

For example, suppose you take only 34 (= N) of the 64 DCT results and choose 7 (= M) of them, taking 7 out of 34 compared to 7 of 64. Since the number of occasions is much smaller, the number of bits required to represent it is also smaller.

Here, the N value may be determined in advance, and a method of transferring additional information about the N value if it is changed in accordance with a condition such as time. If the N value is variable, control information on the N value is transmitted. The information on the N value may be included in the DCT result and transmitted through a physical channel, or may be transmitted in a L1 (Layer 1) or L2 (Layer 2) message through separate signaling.

7 is a diagram illustrating a third quantization and compression method according to the present embodiment. In the example of FIG. 7, N = 34 is determined and M = 7 is determined. As shown, a DCT result corresponding to indexes 1 to 34 is a value that can be transmitted to a receiver, and a DCT result corresponding to indexes 35 or more is a value not transmitted to the receiver. The DCT result selected as meaningful information among the DCT results corresponding to the first to the 34th indexes is quantized and transmitted to the receiver. The method of selecting meaningful information may be any one of the two methods described above, and the number of DCT results selected of the meaningful information is M.

The DCT result corresponding to a specific index, for example index 1, can always be transmitted to the receiving side. In this case, it is not necessary to transmit the location information of the index 1 to the receiving side. In the example of FIG. 7, there is proposed a method of transmitting location information to a receiving side in two ways. Method 1 is a method of separately transmitting location information in units of DCT results as in the method 1 of FIG. 6. In addition, the method 2 of FIG. 7 may transmit the location information bits (eg, log ₂ ( ₆ C ₃₄ ) bits) of the location information in the same manner as the method 2 of FIG. 6.

Method 1 and Method 2 of FIG. 7 include the location information in the channel quality information transmitted to the physical layer, and illustrates a method of transmitting the information about N in the channel quality information. The information about N may be configured in various ways, for example, information about indexes included in the size or N of the N or indexes excluded from the N. The output signal of the DCT information compression module 130 performing the operation of FIG. 7 is {D ₁ , D ₂ , D ₃ ,. , D _NC }, and the D _i value includes a DCT result or location information.

The DCT information decompression module 160 provided on the receiving side performs decompression on the DCT result value according to the control information transmitted from the transmitting side. For example, in the case of the DCT Lowest M method, the M value is transmitted or the reverse compression is performed on the DCT result value according to the preset M value. That is, when the DCT result for the index of M + 1 or more is 0 and the DCT result for the index of M or less is received from the transmitting side and the IDCT is performed, the transmission information originally transmitted by the transmitting side can be restored. The receiving side according to the DCT Significant M scheme and the DCT Hybrid N-M scheme may also restore transmission information transmitted from the transmitting side according to the above-described method. That is, the received DCT result may be restored according to a predetermined pattern or information, and the DCT result may be restored using the received control information.

Hereinafter, the operation in the information decomposition module 140 will be described.

The information decomposition module 140 decomposes the output of the DCT information compression module 130 and transmits it to the receiver. If the output of the DCT information compression module 130 is transmitted at once without disassembling, the information decomposition module 140 may not perform or decompose data.

The output {D ₁ , D ₂ , D ₃ ,... Of the DCT information compression module 130. , D _NC }, the first transmission method for transmitting all the compressed data at once in a predetermined unit time, and the second transmission method for grouping the compressed data in a predetermined unit and divided by a predetermined unit time And a third transmission method of transmitting the compressed reference data at an initial unit time and transmitting a difference value between the compressed data and the reference data every unit time thereafter.

In the first transmission method, channel quality information (D = {D ₁ , D ₂ , D ₃ ,..., D _NC }), which has undergone a series of DCT processes and compression processes, is pre-specified unit time (eg, TTI (Trasmission). Time Interval)) is transmitted at once. At this time, the specified time interval can be set variably. In addition, the D value is considered to be a preferable example of transmitting information obtained based on the most recently obtained channel quality information. That is, the receiving side receives the received D {D ₁ , D ₂ , D ₃ ,... , D _NC } to check the quality of the channel.

Another example would be to send the averaged values over several previous TTIs. That is, it is also possible to determine the channel quality information by applying a constant weight, a forgetting factor, or the like to a specific number of D values previously received.

In the second transmission method, channel quality information D = {D ₁ , D ₂ , D ₃ ,..., D _NC }, which has undergone a series of DCT and compression processes, is grouped into a predetermined unit (for example, overall channel quality). The information D is grouped in quarter units, and each group is transmitted by dividing the group by unit time (for example, TTI).

8 and 9 are diagrams illustrating a method of sequentially transmitting a specific number of information constituting channel quality information according to an embodiment of the present invention. 8 and 9 illustrate a method of transmitting each piece of information in a specific unit when channel quality information is generated according to the above-described DCT Significant M scheme.

In the case of FIG. 8, each information group may be transmitted during one TTI by grouping information strings consisting of D1 to D9 into four information units. In FIG. 8, t (= 0, 1, 2, 3, 4) is a unit indicating TTI. In the case of FIG. 9, similar to FIG. 8, each piece of information is transmitted during one TTI. However, the example of FIG. 9 is an example of the case where the position information for each bit is divided into several values instead of one value. In the example of FIG. 8, one channel quality information is transmitted every four TTIs. In the example of FIG. 9, one channel quality information is transmitted every five TTIs.

According to the example of FIGS. 8 and 9, when the channel changes rapidly with time, the channel quality information transmitted later does not accurately reflect the change of the channel. Therefore, according to the present invention, there is a need for a method of measuring channel quality information every unit time, selecting a portion of the channel quality information, and transmitting the selected channel quality information to a receiving side.

10 is D {= D ₁ , D ₂ , D ₃ , D ₄ including C ₁ , C ₂ , C ₃ , C ₄ , C ₅ , L ₂ , L ₃ , L ₄ , L ₅ in this example. , D ₅ , D ₆ , D ₇ , D ₈ , and D ₉ }.

The transmitter according to the example of FIG. 10 measures D {= D ₁ , D ₂ , D ₃ , D ₄ , D ₅ , D ₆ , D ₇ , D ₈ , D ₉ } for every TTI, but for each TTI Send part of (e.g., D ₀ , ie C ₁ when t = 0). Preferably, the D values transmitted for each TTI are different from each other. In the example of FIG. 10, D ₁ is transmitted when t = 0, D ₂ and D ₃ are transmitted when t = 1, D ₄ and D ₅ are transmitted when t = 2, and D ₈ and D when t = 3. Send ₉ and send D ₂ , D ₃ when t = 4. Since the transmission pattern may be set in various ways, it is preferable that information transmitted for adjacent TTIs is different from each other. The receiving side may restore the transmission information that the transmitting side intends to transmit by updating the newly received D value to the previously received D value, performing reverse compression and IDCT on it, and adjusting the length.

In the case of the example of FIG. 10, since the channel quality information should be measured more frequently than the example of FIGS. 8 and 9, the amount of calculation may increase. However, there is an advantage of transmitting more accurate information because channel quality information is transmitted every TTI. In addition, the example of FIGS. 8 to 10 transmits only a part of the entire information, thereby reducing the amount of information sent to the receiving side.

8 to 10 may be applied to the DCT Hybrid N-M method and the DCT Lowest M method.

The third transmission method first transmits channel quality information (D = {D ₁ , D ₂ , D ₃ ,…, D _NC }) generated through a series of DCT and compression processes as reference information, and thereafter. In this method, only a difference value between the newly generated channel quality information and the reference information is transmitted. The transmission of the reference information and the difference value may be based on the first transmission method or the second transmission method described above.

11 and 12 illustrate a case in which the reference information and the difference value are transmitted by the first transmission method in an example of the third transmission method.

11 illustrates a case where channel quality information is generated in the above-described DCT Lowest M scheme. When t = 0 is referred to as the reference unit time, channel quality information (C _{1 (t = 0)} , C _{2 (t = 0 ) is} newly performed by performing a series of DCT and DCT Lowest M compression processes at that time. ₎ , C _{3 (t = 0)} , C _{4 (t = 0)} , C _{5 (t = 0)} ) (this is referred to as 'reference information'), and the entire reference information is generated according to the first transmission method. It is sent to the receiver. In subsequent unit times (t = 1, 2, 3, ...), a series of DCT and compression processes are performed to newly generate channel quality information (eg, C _{1 (t = 1)} , C _{2 (t = 1). )} , C _{3 (t = 1)} , C _{4 (t = 1)} , C _{5 (t = 1)} ) are generated, the information transmitted to the receiver is the same as the reference information (t = 1, 2, 3, .. Is a difference value from the channel quality information in the &quot;.&Quot; When the variation information according to the present embodiment is D {= D ₁ , D ₂ , D ₃ , D ₄ , D ₅ }, it is calculated in the same manner as D = C _{(t = 1)} -C _{(t = 0)} Can be.

12 illustrates a case where channel quality information is generated in the above-described DCT Significant M scheme. When t = 0 is referred to as the reference unit time, channel quality information (C _{1 (t = 0)} , L _{2 (t = 0 ) is} newly performed by performing a series of DCT processes and DCT significant M compression processes at that time. _), C _{2 (t = 0)} , L _{3 (t = 0),} C _{3 (t = 0)} , L _{4 (t = 0),} C _{4 (t = 0)} , L _{5 (t = 0),} C _{5 (t = 0)} ) (which _is referred to as reference information) is generated, and the entirety of the reference information is transmitted to the receiving side according to the first transmission method. In subsequent unit times (t = 1, 2, 3, ...), a series of DCT and compression processes are performed to newly generate channel quality information (eg, C _{1 (t = 1)} , L _{2 (t = 1). ),} C _{2 (t = 1)} , L _{3 (t = 1),} C _{3 (t = 1)} , L _{4 (t = 1),} C _{4 (t = 1)} , L _{5 (t = 1),} Even if C _{5 (t = 1)} is generated, the difference transmitted between the reference information and the channel quality information at (t = 1, 2, 3, ...) is referred to as 'change amount information'. Is). When the amount of change information according to the present embodiment is D {= D ₁ , L ₂ , D ₂ , L ₃ , D ₃ , L ₄ , D ₄ , L ₅ , D ₅ }, D = C _{(t = 1)} Can be calculated in the same way as C _{(t = 0)} and L _{(t = 1)} = L _{(t = 0)} .

13 and 14 illustrate a case in which the reference information and the difference value are transmitted by the second transmission method in an example of the third transmission method.

FIG. 13 shows an example of generating channel quality information in the above-described DCT Significant M scheme. When t = 0 is referred to as the reference unit time, channel quality information (L _{(t = 0)} , C _{1 (t = 0) is} newly performed by performing a series of DCT processes and a DCT significant M compression process at that time _. , C _{7 (t = 0)} , C _{8 (t = 0)} , C _{17 (t = 0)} ) (which is referred to as 'reference information') are generated, and the entirety of the reference information is received according to a second transmission method. Is sent to the side. In subsequent unit times (t = 1, 2, 3, ...), a series of DCT and compression processes are performed to newly generate channel quality information (eg, L _{(t = 1)} , C _{1 (t = 1)} Even though C _{7 (t = 1)} , C _{8 (t = 1)} and C _{17 (t = 1} ) are generated, the information transmitted to the receiving side is the same as the reference information (t = 1, 2, 3, ...). ) Is the difference value from the channel quality information in &quot; When the amount of change information according to the present embodiment is D {= D ₁ , D ₂ , D ₃ , D ₄ , D ₅ }, D ₁ = L, D _{2 ~ 4} = C _{2 ~ 4 (t = 1)} − Can be calculated in the same way as C _{2 ~ 4 (t = 0)} . Here, since D ₁ has no change, it may be omitted when the change amount information is transmitted. If D ₁ is changed, the reference information at that time should be retransmitted.

14 shows another example of generating channel quality information in the above-described DCT Significant M scheme. When t = 0 is referred to as the reference unit time, channel quality information (C _{1 (t = 0)} , L _{2 (t = 0 ) is} newly performed by performing a series of DCT processes and DCT significant M compression processes at that time. _), C _{2 (t = 0)} , L _{3 (t = 0),} C _{3 (t = 0)} , L _{4 (t = 0),} C _{4 (t = 0)} , L _{5 (t = 0),} C _{5 (t = 0)} ) (which _is referred to as reference information) is generated, and the entirety of the reference information is transmitted to the receiving side according to the first transmission method. In subsequent unit times (t = 1, 2, 3, ...), a series of DCT and compression processes are performed to newly generate channel quality information (eg, C _{1 (t = 1)} , L _{2 (t = 1). ),} C _{2 (t = 1)} , L _{3 (t = 1),} C _{3 (t = 1)} , L _{4 (t = 1),} C _{4 (t = 1)} , L _{5 (t = 1),} Even if C _{5 (t = 1)} is generated, the difference transmitted between the reference information and the channel quality information at (t = 1, 2, 3, ...) is referred to as 'change amount information'. Is). When the variation information according to the present embodiment is D {= D ₁ , L ₂ , D ₂ , L ₃ , D ₃ , L ₄ , D ₄ , L ₅ , D ₅ }, D _{1 , 2,4,6 , 8} = L _{1 , 2,4,6,8} , D _{3 .5.7.9} = C _{3 .5.7.9 (t = 1)} -C _{3 .5.7.9 (t = 0)} Can be. Here, D _{1 , 2 , 4 , 6 , and 8} have no change, and thus may be omitted when the change amount information is transmitted. When D _{1 , 2 , 4 , 6 and 8} are changed, the reference information of the corresponding time point should be retransmitted.

In the above-described third transmission method, the reference information may be transmitted all at once by the first transmission method, and the change amount information may be divided and transmitted by the second transmission method.

In addition, the reference information needs to be retransmitted as reference information at that time as the channel status or communication environment changes. In this case, the reference information may be retransmitted at a predetermined period, retransmitted according to a request from the receiver, or retransmitted according to a scheduling policy of the transmitter. In addition, such retransmission methods may be overlapped with each other.

In addition, it is preferable to transmit reference information having a large amount of information through the physical layer and the MAC layer, or only through the MAC layer, and transmit change amount information having a relatively small amount of information through the physical layer, but is not limited thereto. Both information and variation information may be transmitted to the physical layer or the MAC layer.

In addition, the method of separately transmitting the reference information and the change amount information may be applied to the same method for transmitting the channel quality information before being compressed.

15 is an example of a mobile terminal to which the present invention can be applied.

As shown, the mobile terminal performs a general control operation for the mobile terminal and performs a specific operation and data processing, and receives an external signal under the control of the controller and transmits data to the receiving side The wireless unit 320, the memory unit 330 for temporarily or permanently storing the specific data, the voice processing unit 340 for inputting and outputting voices through a microphone or a speaker, and performing data processing on the voice signal, and an external device. And an input unit 350 receiving input from the display unit and a display unit 360 displaying data to the outside.

Since the mobile terminal transmits and receives data using a plurality of carriers, the wireless unit 320 transmits data through a plurality of subcarriers. Through the wireless unit 320, the control unit 310 is connected to the channel quality. Can measure information. The information regarding the channel quality, that is, the channel quality information, is controlled by a length adjusting block (not shown) provided inside or outside the controller 310. The data whose size is controlled is DCT performed by a DCT module (not shown) provided inside or outside the controller 310, and the DCT information compression module (not shown) and the information decomposition module (not shown) By operation, data bits of a specific size are separated and transmitted to the receiving side. The length adjusting block, the DCT module, the DCT information compression module, and the information decomposition module may be implemented in hardware or software. The results of each block or module may be stored in the memory unit 330 or the like.

 Those skilled in the art through the above description can be seen that various changes and modifications can be made without departing from the spirit of the present invention. Therefore, the technical scope of the present invention is limited to the contents described in the detailed description of the specification or by the claims.

The present invention has an advantage of efficiently using limited radio resources because it minimizes and transmits the size of transmission information to be transmitted to the receiving side. Since the transmission information may be various information, the present invention may be used in various technical fields. When the present invention is used to transmit channel quality information, it is possible to faithfully deliver channel quality information that varies variably in time and frequency to a base station using only a small amount of control information while minimizing performance degradation of a multicarrier system. That is, by performing DCT (Discrete Cosine Transform) transformation on the measured channel quality information and transmitting only a part of the DCT coefficients thus obtained, it minimizes the overhead of feedback information transmitted to the physical channel and appropriately matches the channel change rate. Channel quality information can be fed back. As a result, the present invention has an advantageous effect of greatly increasing the scheduling gain in the frequency domain to improve system throughput.

Claims (17)

In the method for transmitting data using a plurality of subcarriers, Performing a discrete cosine transform on first data corresponding to information transmitted to a receiving side; Selecting a part of the converted result to perform data processing; And Transmitting the data processing result to a receiving side Data transmission and reception method using a DCT comprising a. The method of claim 1, And generating the first data by adjusting the size of the second data generated at the transmitter side. The method of claim 2, wherein the first data, A method for transmitting and receiving data using DCT generated by inserting some bits or puncturing some bits with respect to the second data. The method of claim 3, And transmitting control information regarding the bits to be inserted or punctured. The method of claim 1, wherein the data processing step, Selecting data of some of the DCT converted first data; And Quantizing the selected data Data transmission and reception method using a DCT comprising a. The method of claim 1, wherein the data processing step, Selecting data having an absolute value equal to or greater than a predetermined size from among the DCT converted first data; And Quantizing the selected data and the index of the corresponding data Data transmission and reception method using a DCT comprising a. The method of claim 1, wherein the data processing step, Selecting data of some of the DCT converted first data; Reselecting data having an absolute value equal to or greater than a predetermined size among the selected data; And Quantizing the reselected data and the index of the data Data transmission and reception method using a DCT comprising a. The method of claim 1, And transmitting control information regarding some data selected from the converted results to a receiving side. The method according to any one of claims 1, 5 and 6, When the first data is generated every unit time, The data processing result is a data transmission and reception method using a DCT transmitted to the receiving side every unit time. The method of claim 5, wherein the step of transmitting to the receiving side Grouping the quantized data into predetermined units; And Transmitting the grouped data in unit time Data transmission and reception method using a DCT comprising a. The method of claim 6, wherein the step of transmitting to the receiving side, Grouping the quantized first data to include at least one data and an index thereof; And Transmitting the grouped data in unit time Data transmission and reception method using a DCT comprising a. The method of claim 6, wherein the transmitting to the receiving side comprises: When the first data is generated every unit time, Grouping the quantized first data such that at least one data and an index thereof are included every unit time; And Transmitting group data corresponding to a corresponding unit time among the quantized first data to a receiver Data transmission and reception method using a DCT comprising a. The method of claim 1, wherein the transmitting to the receiving side comprises: When the first data is generated every unit time, A reference data transmission step of transmitting the first data processed in the initial unit time to a receiving side; Variable data transmission step of transmitting a difference value between the first data processed data and the reference data in the subsequent unit time to the receiving side Data transmission and reception method using a DCT comprising a. The method of claim 1, The information transmitted to the receiving side is a data quality transmission and reception method using DCT which is Channel Quality Information (CQI). In the method for receiving data using a plurality of subcarriers, Receiving data corresponding to a part of the entire bit string transmitted by the transmitter at a specific time unit; Restoring the entire bit string by performing data processing on the received bit string; And Performing an Inverse Discrete Cosine Transform on the restored data Data transmission and reception method using a DCT comprising a. In a mobile terminal for transmitting and receiving data using a plurality of subcarriers, A DCT module for performing Discrete Cosine Transform (DCT) on first data corresponding to information transmitted to a receiving side; A data processing module which selects a part of the output of the DCT module to perform data processing; and Wireless module for transmitting the results of the data processing module to the receiving side Mobile terminal comprising a. In a mobile communication system for transmitting and receiving data using a plurality of subcarriers A wireless module configured to receive data corresponding to a part of the entire bit string transmitted by the mobile terminal in a specific time unit; A data processing module configured to recover the entire bit string by performing data processing on the received bit string; IDCT module performing an Inverse Discrete Cosine Transform (IDCT) on the restored data Mobile communication system using a DCT comprising a.

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