KR101231805B1 - Frame deformatting apparatus for data channel - Google Patents

Abstract

According to an embodiment of the present invention, a data channel frame deformatting apparatus includes a PRB location search and storage unit for searching for a location of a physical resource block on which actual data is recorded based on a data channel allocation method, and a location of the found physical resource block. A PRB reading and extracting unit that reads the buffer unit to be recorded, the positions of the physical resource blocks stored in the buffer unit, and outputs a counter signal each time an RE is extracted from the symbol corresponding to the read position; And a counter unit for increasing a counter value, and a mapping unit for mapping a frequency index to an RE to which data is allocated in the physical resource block based on the counter value.

As described above, the present invention finds a physical resource block (PRB) in the shortest time and detects a frequency index to which data is allocated according to an RS pattern, thereby demodulating the downlink data channel of the high speed mobile communication system. By shortening, there is an effect of reducing the overall processing delay time.

LTE, Demodulator, RE, PRB, Resource Block, RS

Description

FRAME DEFORMATTING APPARATUS FOR DATA CHANNEL}

The present invention relates to the de-formatting of data channel frames in a mobile communication system, and more particularly, to find a PRB in the shortest time and to detect a frequency index to which data is assigned according to an RS pattern to minimize processing delay time. An apparatus for deformatting data channel frames.

The present invention is derived from the research conducted as part of the IT growth engine technology development project of the Ministry of Knowledge Economy [Task management number: 2006-S-001-04, Task name: Development of adaptive wireless access and transmission technology for 4G mobile communication] .

Demodulation in the OFDM scheme is performed in the reverse order of generating a signal in the modulator of the base station. First, the guard interval is removed from the received signal and then transformed into a signal in the frequency domain by Discrete Fourier Transform (DFT). The guard band is removed from the converted signal to restore a data set consisting of only the physical channel and the physical signal. This data set includes various types of control channels, data channels, broadcast channels, and physical signals.

The data set is composed of one OFDM symbol, and each OFDM symbol has a frequency resource of a length determined by the standard.

Of the physical signals, RS (Reference Signal) is discontinuously assigned to a specific OFDM symbol. By extracting the RS from the physical signal, the channel between the base station and the terminal is estimated.

The data channel includes a data bit stream for transferring from the base station to the terminal. One of the main parts of the demodulator is the frame deformatter, which extracts this data's resources.

Meanwhile, the modem of the terminal must demodulate and decode the received data at a predetermined time. To do this, we need to apply an algorithm that can reduce latency in each part of the modem processing data.

Among demodulators in an OFDM wireless communication system, typical demodulators are as described in the Korean Patent Application No. 2007-7030636. First, the transmitter reverses the order of modulation in the transmitter. The OFDM transmitter first removes this guard interval since an Inverse Fast Fourier Transform (IFFT) transformation is performed and then a guard interval is inserted. Next, FFT transform is performed on the data of which length is removed. The FFT transformed signal is divided into a control channel and a data channel. Among them, a channel between a transmitter and a receiver is found by using a demodulation reference signal (RS) generated by using a known sequence. The separated data and signals are then used to determine the original signal.

The LTE Advanced standard refers to Release 10 among mobile communication standards standardized by the Third Generation Partnership Project (3GPP). The specification referred to below refers to Release 10.

In a high speed mobile communication system that satisfies the above standard, there is a condition that a modem constituting the physical layer must satisfy. The processing time from demodulating and decoding the downlink data channel to sending feedback to the uplink should be less than 4 ms. To meet these requirements, each part of the modem must be designed to have minimal processing time.

The present invention satisfies the above-described requirements. The present invention seeks to find a physical resource block (PRB) in the shortest time, and detects a frequency index to which data is allocated according to an RS pattern, thereby deformatting a data channel frame. The present invention provides a data channel frame deformatting apparatus capable of minimizing processing time.

The object of the present invention is not limited to the above-mentioned object, and other objects not mentioned will be clearly understood by those skilled in the art from the following description.

According to an embodiment of the present invention, a data channel frame deformatting apparatus includes a PRB location search and storage unit for searching for a location of a physical resource block on which real data is recorded based on a data channel allocation method, and a location of the found physical resource block. A PRB reading and extracting unit which reads the position of the physical resource block stored in the buffer unit, and outputs a counter signal each time an RE is extracted from a symbol corresponding to the read position, and the counter A counter unit for increasing a counter value based on a signal and a mapping unit for mapping a frequency index to an RE to which data is allocated in the physical resource block based on the counter value.

The buffer unit of the deformatting apparatus for a data channel frame according to an embodiment of the present invention includes four buffers, and the width and length of each buffer may be determined based on the number of PRBs.

The present invention finds a physical resource block (PRB) in the shortest time and detects a frequency index to which data is allocated according to an RS pattern, thereby reducing demodulation time of a downlink data channel of a high-speed mobile communication system and This can reduce the processing delay time.

The objects and effects of the present invention and the technical configurations for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intentions or customs of the user, the operator, and the like.

The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. The present embodiments are merely provided to complete the disclosure of the present invention and to fully inform the scope of the invention to those skilled in the art, and the present invention is defined by the scope of the claims. It will be. Therefore, the definition should be based on the contents throughout this specification.

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

In an embodiment of the present invention, a demodulation time of a downlink data channel of a fast mobile communication system is found by finding a physical resource block (PRB) in the shortest time and detecting a frequency index to which data is allocated according to an RS pattern. A deformatting apparatus for a data channel frame that can shorten the time will be described.

1 is a block diagram illustrating an apparatus for deformatting a data channel frame according to an exemplary embodiment of the present invention.

Referring to FIG. 1, a deformatting apparatus for a data channel frame according to an exemplary embodiment of the present invention may include a PRB position search and storage unit 100, a buffer unit 120, a PRB read and extract unit 140, and a counter unit 160. ) And the mapping unit 180.

The subframe used in the embodiment of the present invention conforms to the LTE Advanced standard. That is, according to the specification, 10 subframes having a length of 1 ms are gathered to form a frame, and a frame having a length of 10 ms is repeated.

As described above, the structure of the subframe according to the embodiment of the present invention will be described with reference to FIG. 2.

2 illustrates an example of a downlink subframe structure according to the LTE Advanced standard.

As shown in Fig. 2, the subframe structure consists of a time axis and a frequency axis. The frequency axis represents a frequency assigned to a physical channel or a physical signal. For example, if a subcarrier band is 15 kHz and there are 1,200 subcarriers, the carrier occupies an 18 MHz band. In this case, each sub-carrier becomes one resource element (RE). That is, FIG. 2 illustrates a case in which 14 OFDM symbols constitute one subframe on the time axis. Of the 14 symbols, the first three (0 to 2) are resources allocated for the control channel, and the eleven symbols (3 to 13) in the hatched portion are resources allocated to the data. The OFDM symbols allocated to the control channel may be one, two, or three, not fixed, and in each case, 13, 12, or 11 data channels.

The frame deformatting apparatus according to an embodiment of the present invention separates resources consisting of time and frequency allocated for each physical channel. If FIG. 2 shows where the data channel is on the time axis, FIG. 3 shows where the data channel is on the frequency axis. Twelve resource elements (RE: hereinafter referred to as 'RE') are defined as one resource block (RB) and assigned in resource block units when frequency bands are assigned to physical channels. .

FIG. 3 shows an example of a system in which the entire frequency band is composed of 25 resource blocks, and indicates that 13 resource blocks, which are hatched portions, are resources allocated to one terminal.

In the example of FIGS. 2 and 3, the data channel resource is located at 3 13 symbol positions in a subframe in time, and occupies resource blocks of 0 to 4, 10 to 14, and 20 to 22 in each symbol.

FIG. 4A shows what is shown in FIGS. 2 and 3 in one diagram. The hatched portion is the portion where the data resource is allocated. 4B is the same as FIG. 4A, but shows a case in which a checkered portion of the OFDM symbol 7 10 is allocated to a broadcast channel and thus no data channel is allocated. The broadcast channel is allocated to only one subframe among the 10 subframes.

A frame deformatting apparatus that receives a frame having such a subframe structure is processed for each subframe, and the PRB location search and storage unit 100 performs a physical resource block (PRB) in a subframe according to a resource allocation method. After that, the PRB corresponding to the searched position is recorded in the buffer unit 120. The resource allocation method used in the PRB location search and storage unit 100 is according to the LTE Advanced standard, and a description thereof is as follows.

According to the LTE Advanced standard, resource allocation schemes can be classified into three types of data channels, and three schemes are represented as Type 0-2.

First, in type 0 resource allocation, several PRBs are grouped into one group to define a resource block group (RBG), and a group to be allocated is designated in a bitmap format.

In type 1 allocation, like in type 0, a resource block group is designated in a bitmap format, but only one resource block is allocated within the resource block group.

In type 2, a mapping between a virtual resource block (VRB) and a resource block is defined, and the virtual resource block is continuously allocated. However, according to the virtual resource block to resource block mapping rule, the actual resource blocks are discontinuously allocated on the frequency axis.

As described above, the three resource allocations apply equally to all OFDM symbols except Type 2. In the case of type 2, this is not always the case, however, where different mappings are applied to symbols 0 6 and 7 13.

The PRB location search and storage unit 100 of the data channel deformatting apparatus according to an embodiment of the present invention will be described below to search for a resource allocation location of data according to the resource allocation method described above.

A method of searching for a resource allocation position is to find a PRB to which data is allocated in a subframe, and a method of finding the allocated PRB can be found according to the above three types of resource allocation methods.

Once the location to which the resource is allocated is identified, it needs to be written to the buffer to apply every OFDM symbol. For this reason, the width and depth of each of the buffers 0, 1, 2, and 3 (121, 122, 123, and 123) in the buffer unit 120 must be set to represent the total number of PRBs. For example, a system with 25 PRBs requires 5 bits. The addresses of the buffers 0, 1, 2, and 3 (121, 122, 123, 123) are sequentially increasing values, and the data represents the positions of the actual PRBs.

That is, FIG. 5A shows a buffer address and data when storing the resource allocation of FIG. 4A in a buffer, and FIG. 5B shows a buffer address and data when storing the resource allocation of FIG. 4B in a buffer. Therefore, when the buffers 0, 1, 2, and 3 (121, 122, 123, and 123) are sequentially read, the positions of the PRBs to which the actual data are allocated can be known.

Meanwhile, the buffer unit 120 used in the frame deformatting apparatus according to an embodiment of the present invention uses four buffers, that is, buffers 0, 1, 2, and 3 (121, 122, 123, and 123). The reason why the buffer unit 120 is composed of four buffers is as follows.

Depending on the resource allocation method, the mapping applied to the symbols 0 to 6 and 7 to 13 may be different. In addition, the mapping differs depending on the resource allocation in the same manner depending on the presence of a broadcast channel or a synchronization signal. As a result, four combinations are possible, so four buffers are used. When there is a broadcast channel or a synchronization signal in one subframe, a PRB buffer to be applied to OFDM symbols 0 to 6 and a PRB buffer to be applied to OFDM symbols 7 to 13 are required. In the absence of a broadcast channel or sync signal, two PRB buffers are required as well. That is, up to two PRB buffers are used in one subframe. However, because 10 subframes are grouped together to form one frame, the design has four PRB buffers. Two PRB buffers are sufficient because the buffer can be reused in case of subframe control.

When the buffer unit 120 having the above structure is used, the PRB positions are calculated only once for the OFDM symbols in the subframe and are reused. Doing so reduces the processing latency required to find the PRB.

The PRB reading and extracting unit 140 sequentially reads the PRBs stored in the buffers 0, 1, 2, and 3 (121, 122, 123, and 123), extracts an RE having actual data information from the read PRB, and then RE Each time is extracted, a predetermined counter signal is provided to the counter unit 160.

The following describes the process of extracting an RE.

It depends on whether or not there is an RS in the OFDM symbol. In the case where there is no RS, data is allocated to all 12 REs of the PRB. If there is RS, data is allocated to 8 REs except 4 to which RS is allocated. For reference, if the base station transmit antenna is one, since two RSs are used in one PRB, 10 REs are allocated to the data. When the number of REs is determined for each OFDM symbol according to the presence or absence of RS, a counter signal is generated as many as the number of REs per symbol.

The counter unit 160 determines the RE counter increment based on the number of input counter signals.

The mapping unit 180 maps the frequency index to the REs to which data in each PRB is allocated based on the RE counter increment value.

The processing delay time that occurs during the frequency mapping process depends on how to process the process of determining whether RS should be allocated to a specific RE or data should be allocated from a symbol to exclude the RS.

6A to 6C are diagrams illustrating three RS patterns allocated to a PRB. The positions of RSs may be hopped according to a cell ID indicating a cell to which a base station belongs. That is, in the case of " cell ID% 3 = 0, 1, 2 of base station ", the patterns correspond to Figs. 6A to 6C, respectively. If the OFDM symbol without RS, the frequency index increase value in the RB is 1, and if the OFDM symbol with RS, the frequency index in the RB is 1, 2 or 2 and according to the pattern shown in Figs. 6A to 6C. 1 alternates

7A to 7D illustrate results of finding a frequency index of an RE of each PRB in a mapping unit according to an exemplary embodiment of the present invention. That is, FIG. 7A illustrates a case in which all 12 REs are used as data resources for each PRB in the case of an OFDM symbol without RS allocation, and FIGS. 7B to 7D show RS patterns of FIGS. 6A to 6C, respectively, when RS is allocated. This is the result of mapping frequency indices for the case where 1,2,3 is applied. Creating a frequency index of data in this way allows frame deformatting without processing delay even if RS is allocated.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand. For example, those skilled in the art can change the material, size, etc. of each component according to the application field, or combine or replace the disclosed embodiments in a form that is not clearly disclosed in the embodiments of the present invention, but this also It does not depart from the scope of the invention. Therefore, it should be understood that the above-described embodiments are to be considered in all respects as illustrative and not restrictive, and that these modified embodiments are included in the technical idea described in the claims of the present invention.

1 is a block diagram illustrating an apparatus for deformatting a data channel frame according to an exemplary embodiment of the present invention.

2 illustrates an example of a downlink subframe structure according to the LTE Advanced standard.

3 is a diagram illustrating a PRB structure of a frequency axis in an OFDM symbol,

4A is a view showing what is shown in FIGS. 2 and 3 as one,

4B is a diagram illustrating a case in which a checkered portion of OFDM symbols 7 to 10 is allocated to a broadcast channel and thus no data channel is allocated.

FIG. 5A is a diagram illustrating a buffer address and data when storing the resource allocation of FIG. 4A in a buffer; FIG.

5B is a diagram illustrating a buffer address and data when the resource allocation of FIG. 4B is stored in a buffer.

6A to 6C are diagrams illustrating three RS patterns allocated to a PRB.

7A to 7D illustrate results of finding a frequency index of an RE of each PRB in a mapping unit according to an exemplary embodiment of the present invention.

Claims (5)

A PRB location retrieval and storage unit for retrieving a location of a physical resource block on which real data is recorded based on a data channel allocation method; A buffer unit in which the position of the found physical resource block is recorded; A PRB reading and extracting unit for reading a position of a physical resource block stored in the buffer unit and outputting a counter signal each time an RE is extracted from a symbol corresponding to the read position; A counter unit for increasing a counter value based on the counter signal; A mapping unit for mapping a frequency index to an RE to which data is allocated in the physical resource block based on the counter value Deformatting device for data channel frames. The method of claim 1, The buffer unit is characterized by consisting of at least four buffers having sequentially increasing addresses Deformatting device for data channel frames. The method of claim 2, The buffer unit, First and second buffers in which the position of the physical resource block in which the actual data is located is recorded in a symbol section in which a broadcast channel or a synchronization signal is present in a subframe; And third and fourth buffers in which the positions of the physical resource blocks in which the actual data are located are recorded in symbol periods without a broadcast channel or a synchronization signal in the subframe. Deformatting device for data channel frames. The method according to claim 2 or 3, The width and depth of each buffer in the buffer unit is determined by the total number of physical resource blocks Deformatting device for data channel frames. The method of claim 1, The PRB read and extract unit, After determining the number of RE for each symbol according to the presence or absence of RS in the symbol characterized in that for generating a counter signal corresponding to this Deformatting device for data channel frames.

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