JP2013017227A - Method and apparatus for allocating resources in single carrier-frequency division multiple access system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for allocating resources for randomizing interference between adjacent cells.SOLUTION: An apparatus and a method for allocating resources in a Single Carrier-Frequency Division Multiple Access (SC-FDMA)communication system are provided. The apparatus and the method determines whether to performs inter-subband hopping on a resource unit for a terminal on a frequency axis along which at least two subbands are defined, at each predetermined hopping time, determines whether to perform mirroring on a cell basis, selects a resource unit by selectively inter-subband hopping or mirroring the resource unit for the terminal according to the determination, and allocates the selected resource unit to the terminal.

Description

  In the present invention, a packet data channel and a control channel are transmitted in the same transmission period in a single carrier frequency division multiple access (hereinafter referred to as "SC-FDMA") wireless communication system. In particular, the present invention relates to a method and apparatus for efficiently allocating control channel transmission resources.

  FIG. 1 is a block diagram showing a configuration of a transmitter in an LFDMA (Localized FDMA) system in an SC-FDMA system. FIG. 1 shows a method in which this transmitter uses a discrete Fourier transform (hereinafter referred to as “DFT”) and an inverse fast Fourier transform (hereinafter referred to as “IFFT”). As an example, other transmitter implementations are possible.

  Referring to FIG. 1, the use of DFT and IFFT facilitates changing LFDMA system parameters with low hardware complexity. Looking at the difference between Orthogonal Frequency Division Multiplexing (hereinafter referred to as “OFDM”) and SC-FDMA in terms of transmitter configuration, an LFDMA transmitter is multiplexed at an OFDM transmitter. A DFT precoder 101 is further included at the front end of the IFFT processor 102 used for transmitting the carrier wave. In FIG. 1, a transmission (TX) modulation symbol 103 is input to the DFT 101 in units of blocks. The output of the DFT is mapped to the IFFT input in a band composed of continuous subcarriers. The mapper 104 performs a function of mapping transmission modulation symbols to actual frequency bands.

  FIG. 2 is a diagram illustrating an example in which a terminal (User Equipment: hereinafter referred to as “UE”) in a conventional SC-FDMA system transmits data through arbitrarily assigned resources.

  Referring to FIG. 2, one resource unit (hereinafter referred to as “RU”) 201 is defined by one or more subcarriers in the frequency domain, and one or more SC− in the time domain. Defined by FDMA symbol.

  For data transmission, two RUs indicated by diagonal lines are assigned to UE1, and three RUs indicated by dots are assigned to UE2.

  The RU used by the UE1 and the UE2 to transmit data is fixed in time and continuously uses a predetermined frequency band. Such a resource allocation scheme or data transmission scheme maximizes system performance through limited system resources by selectively allocating frequency resources with good channel conditions to each UE. For example, blocks shown with diagonal lines provide UE1 with radio channel characteristics that can be compared to other frequency bands, while blocks shown with dots show radio channel characteristics that are better than other frequency bands to UE2. To provide. The selective allocation of resources with a better channel response is usually referred to as frequency selective resource allocation or frequency selective scheduling. As described above, uplink data transmission from the UE to the base station (Node B) has been described as an example, but this frequency selective scheduling can also be applied to downlink data transmission from the base station to the UE. . Also in the case of the downlink, RUs indicated by diagonal lines and dots indicate resources used when the base station transmits data to UE1 and UE2.

  However, this frequency selective scheduling is not always efficient. For example, in the case of a UE moving at high speed, this frequency selective scheduling is not easy because the channel state changes rapidly. More specifically, the base station scheduler allocates a frequency band having a relatively good channel state to a predetermined UE at a predetermined time. The UE receives resource allocation information from the base station, and allocates the allocated resource. In transmitting data via, the UE is placed in a channel environment that has already changed significantly. Therefore, this selected frequency band cannot be guaranteed to be a relatively good channel condition for the UE.

  Even if a small amount of frequency resources are continuously required for data transmission, such as Voice over Internet Protocol (VoIP) services, the UE may be able to monitor its channel state for frequency selective scheduling. Signaling overhead may increase signaling overhead. In this case, it is more efficient to use a frequency hopping scheme than frequency selective scheduling.

  FIG. 3 is a diagram illustrating frequency hopping in a conventional FDMA system.

  Referring to FIG. 3, the frequency resources allocated to one UE for data transmission change over time. Such frequency hopping has the effect of randomizing channel quality and interference during data transmission. In other words, since the data is transmitted on frequency resources that change over time, this data has different channel characteristics from time to time, and different UEs in neighboring cells will interfere with the data and thus obtain a diversity effect. .

  However, in the SC-FDMA system as shown in FIG. 3, it is difficult to execute frequency hopping when the RU hops in an independent pattern. For example, it does not matter if RUs 301 and 302 are assigned to different UEs. However, once all of RUs 301 and 302 are assigned to one UE, they hop to the location of RU 303 and RU 304 by frequency hopping at the next transmission time. Since RU 303 and RU 304 are not continuous RUs, the UE cannot transmit data on these two RUs.

  In this connection, in the SC-FDMA system, in order to obtain frequency diversity, a mirroring method that replaces the frequency hopping method has been proposed.

  FIG. 4 is a diagram showing mirroring.

  Conventionally, the RU moves symmetrically with respect to the center frequency of all frequency bands available for data transmission. For example, at the next transmission time in cell A, RU 401 is mirrored to RU 403 and RU 402 is mirrored to RU 404. In the same way, at the next transmission time in cell B, RU 405 is mirrored to RU 406. Such mirroring allows continuous RUs to hop seamlessly, thereby enabling frequency hopping while satisfying a single carrier property during frequency hopping.

  However, the frequency hopping method for obtaining frequency diversity has a disadvantage that the hopping pattern is fixed because there is no method for moving the position of the RU without mirroring based on the center frequency. Such a method can obtain a certain degree of frequency diversity, but it means that interference randomization is difficult. Since the RU hopped to the opposite side returns to its original RU location by mirroring, there is only one applicable RU movement pattern. Therefore, even when there are a plurality of cells, each cell cannot have a different pattern.

  Referring to FIG. 4, when a RU 402 indicated by a dot is assigned to a UE in cell A and a RU 405 indicated by one diagonal line is assigned to a UE in cell B during a predetermined time, Since only the hopping pattern can be used in the mirroring scheme, the UE in cell A interferes with the UE in cell B. If the cell B UE is in the vicinity of cell A, this causes significant interference to the cell A UE. As a result, the reception quality of the UE of the cell A that uses the RU indicated by the dots is deteriorated.

Special table 2009-544189

  Accordingly, the present invention has been proposed to solve the above-described problems of the prior art, and the purpose of the present invention is to randomize interference between adjacent cells when a mirroring scheme is used to obtain frequency diversity. It is an object of the present invention to provide a resource allocation method and apparatus for realizing the above.

  Another object of the present invention is to provide a transmission / reception apparatus that determines whether or not to perform mirroring at each hopping time according to a different mirroring on / off pattern for each cell and uses this.

  A further object of the present invention is to determine whether to perform frequency hopping and mirroring at each hopping time according to a different pattern for each cell, where frequency hopping can be supported to increase the frequency diversity effect. It is to provide a transmitting / receiving device to be used.

  To achieve the above object, according to one aspect of an embodiment of the present invention, there is provided a method for allocating resources to a terminal (UE) in a single carrier frequency division multiple access (SC-FDMA) communication system. . In the above method, on a frequency axis where at least two subbands are defined, whether or not to perform hopping between the subbands at a predetermined hopping time point and mirroring is performed for a resource unit for a terminal. Determining whether to perform by cell, and according to the determination, select a resource unit by selectively performing hopping and mirroring between the subbands on the resource unit for the terminal, and select the selection Assigning the assigned resource unit to the terminal.

  According to another aspect of embodiments of the present invention, a method for receiving resource allocation from a base station in a single carrier frequency division multiple access (SC-FDMA) communication system is provided. The method performs mirroring on whether or not to perform hopping between subbands at a predetermined hopping time point for a resource unit for a terminal on a frequency axis on which at least two subbands are defined. Selecting a resource unit by selectively performing hopping and mirroring between the sub-bands on the resource unit for the terminal according to the determination, and determining whether to select the resource unit Transmitting data to the base station using a resource unit.

  According to still another aspect of the embodiment of the present invention, a base station apparatus that allocates resources to a terminal (UE) in a single carrier frequency division multiple access (SC-FDMA) communication system is provided. Whether the base station apparatus performs hopping between the subbands at a predetermined hopping time point on a resource unit for a terminal on a frequency axis on which at least two subbands are defined, and mirroring Resource units allocated to the terminal by selectively executing hopping and mirroring between the sub-bands on the resource unit for the terminal according to the determination. And a mapper for classifying data received from the terminal according to information on the selected resource unit received from the scheduler, and a decoder for decoding the classified data. It is characterized by.

  According to yet another aspect of an embodiment of the present invention, a terminal (UE) apparatus for transmitting data to a base station in a single carrier frequency division multiple access (SC-FDMA) communication system is provided. The terminal device performs mirroring on whether or not to perform hopping between the subbands at a predetermined hopping time point on a resource unit for the terminal on a frequency axis on which at least two subbands are defined. A data transmission controller for determining whether to execute each cell, and a resource selected by selectively performing hopping and mirroring between the sub-bands on the resource unit of the terminal according to the determination A mapper for mapping to a unit and transmitting the mapped data to the base station.

  Interference between cells can be advantageously randomized while increasing the frequency diversity effect by turning mirroring on or off at each hopping point according to a different mirroring on / off pattern for each cell.

1 is a block diagram of a transmitter in a conventional LFDMA system that is a type of SC-FDMA system. FIG. It is a figure which shows an example which UE transmits data via the arbitrary allocated resources in the conventional SC-FDMA system. It is a figure which shows an example of the frequency hopping system in the conventional FDMA system. It is a figure for demonstrating mirroring. It is a figure for demonstrating the method by the 1st Embodiment of this invention. It is a figure for demonstrating the method by the 1st Embodiment of this invention. 4 is a flowchart illustrating an operation for selecting a RU in a UE or a base station according to the first embodiment of the present invention. It is a block diagram which shows the structure of UE by the 1st Embodiment of this invention. It is a block diagram which shows the structure of the base station by the 1st Embodiment of this invention. It is a figure which shows the channel structure by the 2nd Embodiment of this invention. It is a figure for demonstrating the method by the 2nd Embodiment of this invention. It is a figure for demonstrating the method by the 2nd Embodiment of this invention. It is a figure for demonstrating the method by the 2nd Embodiment of this invention. It is a figure for demonstrating the method by the 2nd Embodiment of this invention. 6 is a flowchart illustrating an operation for selecting a RU in a UE or a base station according to the second embodiment of the present invention. It is a figure which shows the channel structure by the 3rd Embodiment of this invention. FIG. 10 is a diagram illustrating a method for performing mirroring without relation to HARQ according to a third embodiment of the present invention. FIG. 6 illustrates a method for performing mirroring for each HARQ process according to a third embodiment of the present invention. FIG. 6 illustrates a method for performing mirroring for each HARQ process according to a fourth embodiment of the present invention.

  The features defined in the detailed description of the invention, such as the detailed structure and elements of the invention, are provided to assist in a comprehensive understanding of the embodiments of the invention. Accordingly, it will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the scope or spirit of the invention. . In addition, from the viewpoints of clarity and conciseness, detailed descriptions of functions and configurations well known to those skilled in the art are omitted.

  In order to obtain frequency diversity characteristics while satisfying single carrier characteristics in an uplink SC-FDMA system, an embodiment of the present invention uses a common frequency hopping or mirroring method to transmit data with different RUs at predetermined time points. A method for increasing the randomization of inter-cell interference when transmitting is provided.

  For further understanding of the invention, the data channel is defined as follows.

  Frequency scheduling (FS) band: A set of RUs assigned by frequency selective scheduling, which can be composed of continuous RUs or a discontinuous set of RUs .

  Frequency hopping (FH) band: A set of RUs transmitted to obtain frequency diversity, and these RUs are not assigned by frequency selective scheduling. The FH band can be composed of continuous RUs, or can be composed of a set of RUs that are discontinuously distributed. The FH band can be composed of one or more sub-FH bands.

  Mirroring: RUs are symmetrically hopped from left to right and from right to left with respect to the center subcarrier or center RU within the sub-FH band.

  Hopping time: Refers to the time of hopping or mirroring the assigned RU. Based on the method of applying hopping or mirroring, the RU has the following period.

  1. This period is a slot when supporting Intra-subframe hopping & Inter-subframe hopping.

  2. In the case of supporting only inter-subframe hopping, this period is one subframe.

“First Embodiment”
The first embodiment of the present invention proposes a method for turning on or off mirroring according to a different mirroring on / off pattern for each cell. Using different mirroring on / off patterns for different cells as much as possible and reducing the probability of the same mirroring being applied between cells at the same time maximizes the effect of randomizing interference between cells To do.

  5A and 5B are diagrams for explaining a method according to the first embodiment of the present invention. FIG. 5A is a diagram illustrating slot-based mirroring that is not related to Hybrid Automatic Retransmission request (hereinafter referred to as “HARQ”) operation. FIG. 5B is a diagram illustrating mirroring independently for each HARQ process. It is a figure which shows the method to perform.

  Referring to FIG. 5A, there are a cell 501 and a cell 502 (cell A and cell B). Since it is assumed that intra-subframe hopping is supported, the hopping period is a slot unit. In slot A, in cell A, at each hopping time, on, on, on, off, on, off, off, off,. . . In the cell B, on, off, on, on, off, off, on, on,. . . The mirroring is executed with the pattern 512.

  In cell A, RU 504 is assigned to UE A at hopping time k. Since mirroring is turned on for UE A at the next hopping time (k + 1), UE A uses RU 505 in slot (k + 1). Since mirroring is turned off at the time of hopping (k + 3), UE A transmits data using the same RU 506 as that used in the previous slot (k + 2) in slot (k + 3). Similarly, since mirroring is turned off at the hopping time (k + 6), UE A transmits data in slot (k + 6) using the same RU 507 as the RU used in the previous slot (k + 5).

  In the same manner, in cell B, RU 508 is assigned to UE B in slot k. Since mirroring is turned off at the next hopping time (k + 1), UE B uses RU 509 in slot (k + 1). Since mirroring is turned on at the hopping time (k + 3), UE B uses RU 510 in slot (k + 3). Similarly, since mirroring is turned on at the hopping time (k + 6), UE B uses RU 511 in slot (k + 6).

  In this way, mirroring is turned on or off at each hopping time with a different pattern for each cell. Thus, UEs in different cells can use the same RU in a given slot, but the probability of different cells using the same RU in the next slot is reduced by using different mirroring on / off patterns. The For example, RUs 504 and 508 are assigned to UE A in cell A and UE B in cell B, respectively, in slot k. If UE B is close to cell A, UE B may interfere significantly with UE A. However, since UE A turns on mirroring at the next hopping time (k + 1), UE A transmits data using RU 505 in slot (k + 1), while UE B turns off mirroring. B transmits data using the same RU 509 as the previous slot. Therefore, UE A and UE B use different RUs in slot (k + 1).

  On the other hand, the mirroring method shown in FIG. 5B is similar to FIG. 5A in that the mirroring on / off pattern is applied differently for each cell, and the RU used in the previous slot is used as a reference when applying mirroring. 5A differs from FIG. 5A in that RUs belonging to the same HARQ process are used as a reference. That is, in FIG. 5B, the mirroring of the UE located in the cell 513 (cell A) is turned on at the hopping time point k. Thus, instead of mirroring the RU used in the previous slot (k-1), the UE uses the RU 518 mirrored in the RU 517 used in the previous slot (k-RTT + 1) of the same HARQ process. The RTT indicates a round trip time. When the response to the transmitted data is a negative response (NACK) and the response to the retransmitted data is an acknowledgment (ACK), the initial transmission takes place. Defined as time. Thus, the data sent using RUs 518 and 519 is a retransmitted version of the data sent using RUs 516 and 517, or the same HARQ as the data sent using RUs 516 and 517 Belongs to a process. As described above, HARQ RTT-based mirroring facilitates the definition of a mirroring on / off pattern that uses different RUs during initial transmission and retransmission. However, despite this advantage, managing different mirroring on / off patterns for each HARQ process adds complexity. In this connection, the mirroring on / off pattern is determined as follows.

  (1) Mirroring is turned on / off at each hopping time according to a predetermined sequence. This sequence is required not to indicate the position of the RU for hopping, but to indicate whether mirroring is on or off. Therefore, this sequence consists of two values. Generally, a binary sequence is composed of 0 or 1.

  (2) By applying different patterns between at least adjacent cells, a plurality of sequences are generated so as to minimize RU collision between adjacent cells, and assigned to each cell. For example, a set of orthogonal codes such as Walsh codes is assigned to each cell, and each cell determines mirroring on / off according to the code value 0 or 1 at each hopping time. Alternatively, each cell may determine mirroring on / off according to a pseudo noise (PN) sequence having a different seed value for each cell. Compared to the former method, the latter method increases randomization between arbitrary cells, and thus minimizes RU hopping in the same manner in different cells. In the following, the first embodiment of the present invention will be described with an example of a method based on a PN sequence.

  In order to generate a PN sequence value, a cell-specific seed is used for each cell, and in order to obtain the same PN sequence value, UEs in the same cell receive the same timing information. There must be. This timing information can be shown as a common time frame count, such as the difference between the absolute time and the current time or a system frame number (SFN).

  FIG. 6 is a flowchart illustrating an operation of the UE for determining on / off of mirroring according to the first embodiment of the present invention. In order to receive data from the UE, the base station can perform the same operations.

  Referring to FIG. 6, when the base station schedules a predetermined RU for the UE, the UE generates a PN sequence value in step 601 and checks the generated PN sequence value in step 602. If this PN sequence value is 0, the UE turns off mirroring in step 604. If this PN sequence value is 1, the UE turns on mirroring in step 603. In step 605, the UE selects the location of the RU for the next data transmission according to the mirroring on / off determined in step 603 or step 604. In step 606, the UE transmits data using the selected RU.

  When mirroring is performed, RUs on both sides symmetrically hop with respect to the center of the entire FH band, so that a new RU used in the next slot is detected based on information about the RU used in the previous slot. Can. This mirroring is expressed as equation (1).

Here, r indicates an RU serving as a reference for mirroring. This mirroring criterion is the RU used in the previous slot in FIG. 5A, and the RU used in the previous slot of the same HARQ process in FIG. 5B. H (r) indicates the RU in which the mirroring reference is mirrored during one slot. N _FH indicates the total number of RUs belonging to the FH band.

  FIG. 7 is a block diagram of a UE according to the first embodiment of the present invention.

  Referring to FIG. 7, the data symbol generator 703 generates data symbols to be transmitted. At this time, the amount of data that can be transmitted at every transmission time interval (Transmission Time Interval: TTI) is determined by base station scheduling. A serial to parallel (S / P) converter 704 converts this sequence of data symbols into a parallel symbol sequence. The DFT processor 705 converts this parallel symbol sequence into a frequency signal for SC-FDMA transmission. The DFT size is the same as the number of data symbols generated from the data symbol generator 703. The mapper 706 maps this frequency signal to a frequency resource allocated to the UE based on the RU information received from the data transmission controller 702. At this time, the data transmission controller 702 generates this RU information based on the scheduled RU information and mirroring on / off information. Each cell has a different mirroring on / off pattern according to the PN sequence. Therefore, a PN sequence generator 701 is necessary. According to the method described above, the RU from which data is extracted is determined using the output value of the PN sequence generator 701. The IFFT processor 707 converts the mapped signal into a time domain signal. A parallel to serial (P / S) converter 708 converts this time signal to a serial signal for transmission.

  FIG. 8 is a block diagram showing the configuration of the base station apparatus according to the first embodiment of the present invention.

  Referring to FIG. 8, the S / P converter 807 converts the received signal into a parallel signal, and the FFT processor 806 converts the parallel signal into a frequency domain signal. The demapper 805 demaps the frequency signals of different UEs based on the RU allocation information regarding each UE determined by the uplink scheduler 802. The uplink scheduler 802 generates UE-specific RU information using the scheduled RU information and mirroring on / off information based on the mirroring on / off pattern. A PN sequence generator 801 is required for each cell to have a different mirroring on / off pattern. According to the method described above, the RU from which data is extracted is determined using the output value of the PN sequence generator 801. The IDFT processor 804 converts this demapped signal of UE1 into a time domain signal. The P / S converter 808 converts the time domain signal into a serial signal. The data symbol decoder 803 demodulates the data received from the UE1.

“Second Embodiment”
Hopping on / off between sub-FH bands is combined with mirroring on / off, and the location of RUs for data transmission is selected by selecting one of the combinations so that each cell has a different pattern. It is determined. That is, the resources of the entire system frequency band are divided into an FH band and an FS band, and a channel configuration for providing a sufficient frequency hopping gain in the FH band and sufficiently obtaining a frequency band that can be allocated in the FS band is proposed. To do.

  FIG. 9 is a diagram illustrating a channel configuration according to the second embodiment of the present invention.

  Referring to FIG. 9, sub FH bands 901 and 903 are defined on both sides of the entire frequency band, and a central frequency band between the sub FH bands 901 and 903 is defined as an FS band 902. In this case, the UE using the FH band 902 can obtain a sufficient frequency hopping gain by hopping to the sub-FH bands 901 and 903. Moreover, since the frequency of the FH band 902 is continuously configured so that continuous frequency resource allocation can be maximized, the maximum transmission rate can be increased.

  Next, considering the single carrier characteristics in the above-described channel configuration, sufficient frequency diversity gain is obtained, and at the same time, in order to enable variable RU allocation, between sub-FH bands in each FH band A method for executing hopping and mirroring will be described. Further, as in the first embodiment of the present invention, in order to maximize the interference randomization gain between adjacent cells, according to a specific pattern for each cell, hopping between sub-FH bands is performed for each hopping time point. Apply on / off and mirroring on / off.

  As shown in Table 1, four combinations of on / off of hopping between sub-FH bands and on / off of mirroring are possible. One of these combinations is selected at each hopping point, and hopping or / and mirroring is applied cell by cell using the selected combination in different patterns.

  10A to 10D are diagrams illustrating a method according to the second embodiment of the present invention.

  10A and 10B assume that intra TTI hopping is supported in cell 1001 and cell 1007 (cell A and cell B), so the hopping period is in units of slots.

  Referring to FIGS. 10A and 10B, a sequence combination of 3-4-1-4-2-1-2-3 is selected for cell A and 3-4-2-1 for cell B. The combination of the order of -3-2-1-4 is selected.

  That is, even if cell A uses RU 1002 at hopping time k, RU 1005 is selected by hopping and mirroring between sub-FH bands according to combination 1 at hopping time (k + 1). At the next hopping time (k + 2), according to the combination 4, the RU 1003 is selected by executing only the hopping between the sub-FH bands without applying the mirroring. At the hopping time (k + 4), cell A selects RU 1004 because all hopping and mirroring between sub-FH bands are not applied according to combination 2.

  Cell B selects the same RU 1008 used for cell A at hopping time k. Cell B selects RU 1009 only through hopping between sub-FH bands without applying mirroring according to combination 4, compared to cell A which selects RU 1005 via hopping and mirroring between sub-FH bands according to combination 1 To do. Other UEs in cell B can use the same RU as RU 1005 in slot (k + 1), but rather than interference due to collisions with the same UE, interference from different UEs at each time point is A better interference randomization gain can be provided.

  10C and 10D, the hopping and mirroring between the sub-FH bands as described above is based on the RU used for data transmission before the same HARQ process instead of the RU used at the previous hopping time. To be executed.

  Referring to FIG. 10C, the RU 1013 does not perform hopping between sub-FH bands based on the RU used at the hopping time (k−1), but uses the RU 1014 used for data transmission before the same HARQ process. Hopping between sub-FH bands is performed on the basis of. At hopping time k, combination 4 is set to turn on hopping between sub-FH bands based on RU 1014 and turn off mirroring. Therefore, RU 1013 is selected at hopping time k. Further, since the combination 3 is selected at the hopping time (k + 1), the RU 1012 is selected when the hopping between the sub-FH bands based on the RU 1013 is turned off and the mirroring is turned on.

  Next, a method for selecting a combination of on / off of hopping between sub-FH bands and on / off of mirroring using a predetermined sequence will be described.

  (1) This sequence is not for indicating the position of the RU for hopping, but for determining only four combinations of hopping on / off and mirroring on / off between sub-FH bands. Because there is, a sequence having four values is used. In general, using four quaternary sequences, or generating and combining two binary sequences, four combinations can be generated. At this time, this sequence can be generated by a conventional method, and therefore, a detailed description of this method is omitted here.

  (2) By applying different patterns between at least adjacent cells, a plurality of sequences are generated so as to minimize RU collision between adjacent cells, and assigned to each cell. For example, a set of orthogonal codes such as Walsh codes is assigned to each cell one by one, and each cell selects a combination according to a sequence value at each hopping time. Alternatively, each cell can select a combination according to a PN sequence having a specific seed value for each cell. This method increases inter-cell randomization compared to the method described in the second embodiment, and thus minimizes RU hopping in different manners in different cells. In the following, embodiments of the present invention will be described with examples of methods based on PN sequences.

  In order to generate a PN sequence value, a specific seed is used for each cell, and in order to obtain the same PN sequence value, UEs in the same cell must receive the same timing information. This timing information can be shown as a difference between absolute time and current time or a common time frame count such as SFN.

  FIG. 11 is a flowchart illustrating an operation of a UE according to the second embodiment of the present invention. The same operation is performed when the base station receives data from the UE.

  Referring to FIG. 11, when the base station schedules a specific RU for the UE, the UE generates a PN sequence value in step 1101, and in step 1102, the PN sequence value is 1, 2, 3, Or 4 is checked. If this PN sequence value is 1, the UE selects a combination of mirroring on and hopping on between sub-FH bands in step 1103. If this PN sequence value is 2, the UE selects a combination of mirroring off and hopping off between sub-FH bands in step 1104. If this PN sequence value is 3, the UE selects a combination of mirroring off and hopping on between sub-FH bands in step 1105. If this PN sequence value is 4, the UE selects a combination of mirroring on and hopping off between sub-FH bands in step 1106. In step 1107, the UE selects an RU for data transmission by mirroring and / or hopping according to the selected combination. In step 1108, the UE transmits data using the selected RU.

  The transmitter device and the receiver device according to the second embodiment of the present invention generate one of four values 1 to 4 by the PN sequence generators 701 and 802 to determine the position of the RU, Except for providing the generated value to the data transmission controller 702 and the uplink scheduler 802, the transmitter apparatus and the receiver apparatus according to the first embodiment of the present invention have the same configuration.

“Third Embodiment”
FIG. 12 is a diagram illustrating a channel configuration according to the third embodiment of the present invention.

  In a system in which a plurality of sub-FH bands as shown in FIG. 12 exist and hopping always occurs between the sub-FH bands, a method of determining mirroring on / off according to a different pattern for each cell is proposed. To do. In this case, the use of different mirroring on / off patterns for each cell reduces the probability of performing mirroring at the same time in this different cell, thus maximizing the inter-cell interference randomization. .

  13 and 14 are views for explaining a method according to the third embodiment of the present invention. Specifically, FIG. 13 illustrates a method for performing mirroring independently of HARQ, and FIG. 14 illustrates a method for performing mirroring for each HARQ process.

  Referring to FIG. 13, since it is assumed that both the cell 1301 and the cell 1311 (cell A and cell B) support intra subframe hopping, the hopping period is a slot unit. Within cell A, at each hopping point, on, on, off, off, on, off, off, off,. . . , And in cell B, on, off, off, on, off, off, on, on,. . . The mirroring is executed with the pattern 1320.

  When the RU 1302 in the sub-FH band # 1 is assigned to the UE at the hopping time k in the cell A, the hopping is always applied between the sub-FH bands. Hopping occurs and is mirrored according to the mirroring pattern 1310. Therefore, the UE uses RU 1303 in slot (k + 1). At the next hopping time (k + 2), the UE selects RU 1304 via hopping to sub-FH band # 1 and mirroring off. At the next hopping time (k + 3), hopping to sub-FH band # 2 occurs and mirroring is turned off, so the UE uses RU 1305 in slot (k + 3).

  Cell B defines a different mirroring on / off pattern than cell A. Specifically, mirroring is turned on / off in a different manner at each hopping time corresponding to each cell. Although cell A and cell B can select the same RU at a given hopping time, the third embodiment of the present invention has the possibility that two cells select the same RU at the next hopping time. Reduce.

  For example, if the same RU 1302 and 1312 are assigned to UE A in cell A and UE B in cell B, respectively, during a predetermined time, if UE B is located near cell A, UE A At hopping time k, UE B may experience a large amount of interference. However, since cell A performs both hopping and mirroring between sub-FH bands at the next hopping time (k + 1), UE A transmits data using RU 1303 in slot (k + 1), while the cell Since B does not apply mirroring after performing hopping between sub-FH bands, UE B transmits data using RU 1313 in slot (k + 1). Therefore, UE A and UE B use different RUs in slot (k + 1), thereby avoiding continuous interference from the same UE.

  On the other hand, the mirroring method shown in FIG. 14 is the same as that shown in FIG. 13 in that mirroring is performed after hopping between sub-FH bands and a different mirroring on / off pattern is used for each cell. The mirroring method shown in FIG. 14 is different from that shown in FIG. 13 in that the RU used at the previous transmission time is not a reference, but is mirrored based on the RU in the same HARQ process.

  That is, at the time of hopping (k + RTT), the UE in the cell 1401 (cell A) does not mirror based on the RU used in the previous slot (k + RTT-1), but instead uses the same HARQ process slot (k + 1). The RU 1407 is used by mirroring on the basis of the RU 1406 used in FIG. As described above, HARQ RTT-based mirroring facilitates the definition of a mirroring on / off pattern that uses different RUs during initial transmission and retransmission, thereby maximizing the interference diversity effect.

  The UE determines mirroring on / off in the same manner as in the first embodiment of the present invention except that hopping between sub-FH bands always occurs when selecting an RU.

  In order to realize the third embodiment of the present invention, an example of a hopping pattern equation like Expression (2) will be described. The UE recognizes the resource block used at each transmission time using the hopping pattern equation and the index of the scheduled resource block. Equation (2) uses a sub-band cyclic shifting scheme for hopping between sub-bands.

Here, O _S represents the offset value that tells whether the resource blocks scheduled to the UE is spaced How the cyclic shift reference point, f_s is scheduling grant: the index of the resource blocks allocated by the (grant authorization) H (t) indicates the amount by which this scheduled resource block is circularly moved at the scheduling time (t). f _hop (i) denotes the index of a resource block after applying the hopping at hopping time (i), N_RB denotes the total number of available resource blocks for data transmission, _{N O} and _{N S} are hopping The number of maximum resource blocks that can be scheduled to a UE that executes

If the total number of resource blocks N_RB is not a multiple of the number M of sub-band, a particular subband has a number N _S of small amount of resource blocks than the number N _O resource blocks included in the remaining sub-bands. Equation (2), so I assumed that only one subband has a fewer amount of resources blocks, it is possible to determine the N _O and N _S as in equation (3).

  In the equation (2), h (i) is a parameter indicating the amount of cyclic movement {0, 1,. . . , M} and is selected according to the bit value of the random sequence. h (0) is 0 (h (0) = 0). m (i) has one value in {0, 1} as a parameter for determining mirroring on / off at hopping time (i) and is selected according to the bit value of the random sequence, or According to the bit value of the random sequence, {0, 1,. . . , M} is selected as the x value and can be determined by h (i) = x / 2 and m (i) = xMod (2). When m (i) = 0, mirroring is turned off, and when m (i) = 1, mirroring is turned on.

To illustrate the formula (2) in more detail, the offset O _S at scheduling time of the scheduled resource block is first determined by the first row of equation (2). O _S indicates whether cyclic shift resource blocks are spaced away how much from the cyclic shift reference point.

The reason for the introduction of O _S is as follows. When the total number N_RB of resource blocks is not a multiple of the number M of sub-bands, the sub-bands do not have the same amount of resources, so that hopping between sub-bands may not operate correctly. Therefore, one sub-bands as sub-band to have a number N _O resource block lesser amounts than the number N _S of each of the resource blocks of the remaining sub-bands, O _S is less amount of resources Used to indicate to the UE the subbands that have blocks.

For example, when N_RB is 22 and M is 4, the sub-band has 4 resource blocks in the first sub-band, and each of the remaining sub-bands has 6 resource blocks. Can be configured as follows. In the configuration of the sub-band as described above, when the O _S is less than 4, UE recognizes that the scheduled resource block belongs to a sub-band having a resource block of smaller number.

According to the first conditional statement of equation (2), this scheduled resource block is circularly moved to resource blocks 0 to N _S−1 according to the offset value O _S , and then in the N _S resource blocks. Is mirrored. If m (i) = 0, mirroring is not applied.

If O _S is greater than N _S is the scheduled resource block, because it belongs to the normal sub-bands, after the cyclic shift is performed according to the second conditional sentence of Equation (2), N Mirroring is performed in _O resource blocks. If m (i) = 0, mirroring is not applied.

Based on the configuration of the sub-bands, a plurality of sub-bands has a the N _S resource blocks may be a plurality of remaining subbands are configured to have N _O resource blocks. For example, when the number of subbands is 4, each of the two subbands has 5 resource blocks, and each of the other two subbands includes 6 resource blocks. This example can be easily realized by changing the conditional statement of Expression (2) indicating the scheduled sub-band using the offset value.

“Fourth Embodiment”
Continuous mirroring on / off increases the probability of data transmission from UEs using the same RU in different cells when performing mirroring on or off according to a random pattern by cell. However, when data is transmitted by the HARQ process, at least continuous data transmission situations such as initial transmission and retransmission because it is preferable from the viewpoint of channel quality to obtain sufficient frequency diversity at each transmission time point. The UE needs to select a different RU. For this purpose, the fourth embodiment of the present invention uses a method of generating a random mirroring pattern and determining on / off of mirroring according to the random mirroring pattern, as necessary. suggest. When supporting both intra-subframe hopping and inter-subframe hopping, for one of the two hopping methods, mirroring is always turned on at each hopping point, and the other hopping method is switched on. On the other hand, mirroring is turned on / off with a random mirroring on / off pattern.

  FIG. 15 shows that mirroring is always turned on for inter subframe hopping and mirroring on / off according to a random mirroring on / off pattern for intra subframe hopping according to the fourth embodiment of the present invention. It is a figure which shows the method to determine.

  As in the second embodiment of the present invention, the sub-FH band is located on both sides of the system frequency band, and the FH band is interposed in the central frequency band between the sub-FH bands. As in the third embodiment of the present invention, in order to obtain frequency diversity gain, the RU hops between sub-FH bands at each hopping time.

  Referring to FIG. 15, in cell 1500 (cell A), on, off, off,. . . In the cell 1520 (cell B), off, off, on,. . . Mirroring occurs according to the pattern.

  In cell A, when the RU 1502 is assigned to the UE at the hopping time (k-RTT), the UE selects the RU 1503 by mirroring according to the mirroring on / off pattern at the next hopping time (k-RTT + 1). Mirroring is always executed at the hopping time point k, which is the transmission time point of the same HARQ process. In order to select an RU at a position different from the RU transmitted at the previous transmission time of the same HARQ process, mirror the RU 1502 used in the first slot (k-RTT) at the previous HARQ transmission time. To select RU 1504. Since the mirroring is turned off according to the mirroring on / off pattern at the next hopping time (k + 1), the UE selects the RU 1505. Mirroring is always executed at the hopping time (k + RTT) that is the next transmission time of the same HARQ process. The RU 1504 is mirrored to the RU 1506 in order to select a RU at a position different from the RU transmitted at the previous HARQ transmission time. Since the mirroring is turned off according to this mirroring on / off pattern at the next hopping time (k + RTT + 1), the UE selects the RU 1507.

  In the same manner, in cell B, the RU hops to another sub-FH band by turning on / off mirroring according to a random mirroring on / off pattern at each intra subframe hopping time. That is, when RU 1508 is used in a slot (k-RTT), RU 1509 is selected by turning off mirroring according to this mirroring on / off pattern at the next hopping time (k-RTT + 1). Since mirroring is executed based on the RU 1508 used at the previous transmission time of the same HARQ process at the next HARQ transmission time, the RU 1510 is selected at the hopping time k. Since mirroring is turned off according to the mirroring on / off pattern at the time of hopping (k + 1), RU 1511 is selected. Further, since mirroring is executed based on the RU 1510 used at the previous transmission time of the same HARQ process at the next HARQ transmission time, the RU 1512 is selected at the hopping time (k + RTT). At the time of hopping (k + RTT + 1), mirroring is turned on according to the mirroring on / off pattern, so RU 1513 is selected.

  Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various modifications can be made without departing from the scope and spirit of the invention. The scope of the present invention should not be limited to the above-described embodiments, but should be defined within the scope of the appended claims and their equivalents.

101 DFT Precoder 102 IFFT Processor 103 Transmission (TX) Modulation Symbol 104 Mapper
201 Resource Unit (RU)
301, 302, 303, 304 RU
401, 402, 403, 404, 405, 406 RU
501 cell A
502 cell B
503, 512 Mirroring pattern 504, 505, 506, 507, 508, 509, 510, 511 RU
513 cell A
514 cell B
526, 527 Mirroring pattern 516, 517, 518, 519, 520 RU
521, 522, 523, 524, 525 RU
701 PN sequence generator 702 Data transmission controller 703 Data symbol generator 704 Serial-parallel (S / P) converter 705 DFT processor 706 Mapper 707 IFFT processor 708 Parallel-serial (P / S) converter 801 PN sequence generator 802 Up Link scheduler 803 Data symbol decoder 804 IDFT processor 805 Demapper 806 FFT processor 807 S / P converter 808 P / S converter 901, 903 Sub FH band 902 FH band 1001 Cell A
1007 Cell B
1002, 1003, 1004, 1005 RU
1008, 1009, 1012, 1013, 1014 RU
1201, 1202 Sub-FH band 1301 Cell A
1311 Cell B
1310, 1320 Mirroring pattern 1302, 1303, 1304, 1305 RU
1306, 1307, 1308, 1309 RU
1312, 1313, 1314, 1315 RU
1316, 1317, 1318, 1319 RU
1401 cell A
1410 cell B
1409, 1417 Mirroring patterns 1402, 1403, 1405, 1406 RU
1407, 1408, 1411, 1412 RU
1413, 1414, 1415, 1416 RU
1500 cell A
1520 cell B
1502, 1503, 1504, 1505 RU
1506, 1507, 1508, 1509 RU
1510, 1511, 1512, 1513 RU

Claims (12)

A method for receiving data by a base station in a communication system, comprising:
Transmitting resource allocation information to the terminal;
A resource used to receive data from the terminal is determined according to whether to perform hopping of the terminal and mirroring determined based on the resource allocation information transmitted to the terminal. Steps,
Receiving the data through the determined resource;
Decoding the received data;
A data receiving method comprising: The method of claim 1, wherein the hopping is hopping between subbands. The data receiving method according to claim 1, wherein the mirroring is mirroring within a sub-band. The method of claim 1, wherein whether to perform the mirroring is determined based on a random sequence for each cell. The method according to claim 1, wherein whether or not to perform the hopping and mirroring is determined at a reception time of the data. The method of claim 1, wherein the hopping and mirroring are performed in at least one of a slot and a subframe. A base station apparatus that receives data from a terminal (UE) in a communication system,
A scheduler for allocating resources to the terminal, transmitting resource allocation information, and determining resources used to receive data from the terminal;
A demapper for demapping data received from the terminal through the determined resource;
A decoder for decoding the demapped data;
Have
The scheduler determines resources used to receive the data according to whether to perform hopping and mirroring of the terminal determined based on resource allocation information transmitted to the terminal. Base station equipment. The base station apparatus according to claim 7, wherein the hopping is hopping between subbands. The base station apparatus according to claim 7, wherein the mirroring is mirroring within a sub-band. The base station apparatus according to claim 7, wherein whether to perform the mirroring is determined based on a random sequence for each cell. The base station apparatus according to claim 7, wherein the scheduler determines whether to perform the hopping and mirroring at the time of receiving the data. The base station apparatus according to claim 7, wherein the hopping and mirroring are performed in at least one of a slot and a subframe.

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