KR20130051092A - Method and apparatus for allocation resources in wireless communications system - Google Patents

Abstract

PURPOSE: A resource assignment method of a wireless communication system and a device thereof are provided to assign resources. CONSTITUTION: When a control channel area is included in a data channel area, a resource mapping device(1013) determines a resource area which is moved in the data channel area. The resource mapping device maps a data channel on the moved resource area. The data channel area is indicated by the resource assignment information of the data channel. An ePDCCH(enhanced Physical Downlink Control Channel) mapping device(1009) maps a control channel including the resource assignment information to the control channel area. A frequency multiplexer(1015) transmits multiplexed signals by multiplexing the frequency of the signal mapped on the control channel area and the signal mapped on the data channel area. [Reference numerals] (1001) PDSCH generator; (1003) Scheduler; (1005) PDCCH generator; (1007) ePDCCH generator; (1009) ePDCCH mapping device; (1011) Reference signal generator; (1013) Resource mapping device; (1019) TX processor; (AA) Transmission

Description

Method and apparatus for allocating resources in a wireless communication system {METHOD AND APPARATUS FOR ALLOCATION RESOURCES IN WIRELESS COMMUNICATIONS SYSTEM}

The present invention relates to resource allocation in a wireless communication system, and more particularly, to a method and apparatus for allocating a data channel for increasing resource efficiency in an orthogonal frequency division multiplexing (OFDM) communication system.

Mobile communication systems using wireless communication technology have been developed to provide voice services while guaranteeing user activity. Mobile communication systems are gradually expanding to not only voice but also data services, and now they have evolved to provide high-speed data services. However, in a mobile communication system in which a service is currently provided, a lack of resources and users demand higher speed services, and therefore, a more advanced mobile communication system is required.

In response to these demands, one of the systems being developed as a next-generation mobile communication system, the specification work for Long Term Evolution-LTE (LTE-A) is under way in the 3rd generation partnership project (3GPP). LTE-A is a technology for implementing high-speed packet-based communication having a transmission rate of up to about 1 Gbps. Various techniques are discussed for this purpose, for example, a technique of multiplexing the structure of a network so that a plurality of base stations overlap service in a specific region, or a technique of increasing the number of frequency bands supported by one base station.

Meanwhile, in the LTE system, the control channel is designed based on distributed transmission. This is to minimize the interference between cells, to distribute the interference, and to obtain frequency diversity gain. However, LTE-A assumes a wireless environment in which the distance between cells becomes very close and the interference between cells is very large. Therefore, a control channel designed on the basis of distributed transmission has a problem that interference between cells is inevitable. In addition, in the LTE-A system, it is also possible to transmit a control channel using a frequency selective gain, which can be used to transmit the control channel with less resources. On the other hand, when the channel change of a user equipment (UE) is fast, The disadvantage is that this control channel may not be received.

That is, in the evolved system, not only the transmission of the existing frequency diversity gain but also the transmission of the frequency selective gain are supported. As a result, a frequency-divided control channel transmission occurs, which requires multiplexing with the data channel. If the transmission unit of the control channel is the same as the transmission unit of the data channel, there is no problem in multiplexing. However, since the control channel transmits a smaller amount of information than the data channel, the basic unit of transmission of the control channel is the data channel. It becomes smaller than the unit of. In this case, when the control channel and the data channel are multiplexed in the data channel area, some resources cannot be used because the area that the control channel autonomously cannot fill all the basic units for data transmission. Therefore, as the control channel transmission area increases, resources that cannot be used in the system also increase. Therefore, there is a need for a resource allocation scheme to prevent such a problem and to increase resource efficiency in data channel and control channel multiplexing.

The present invention provides a method and apparatus for performing resource allocation in a wireless communication system.

The present invention provides a resource allocation method and apparatus for increasing resource efficiency in a wireless communication system.

The present invention provides a method and apparatus for transmitting a control channel using a different reference signal or a different transmission scheme in a wireless communication system using the OFDM technology so that the terminal can efficiently receive.

A method according to a preferred embodiment of the present invention comprises: A method of allocating resources in a wireless communication system, comprising: transmitting a control channel including resource allocation information of a data channel in a control channel region, and if the control channel region is included in a data channel region indicated by the resource allocation information And determining a resource region in which the data channel region is moved by the control channel region, and transmitting a data channel in the moved resource region.

Method according to another embodiment of the present invention; A resource allocation method in a wireless communication system, comprising: receiving a control channel including resource allocation information of a data channel in a control channel region; and if the control channel region is included in a data channel region indicated by the resource allocation information And determining a resource region in which the data channel region is moved by the control channel region, and receiving a data channel in the moved resource region.

Apparatus according to an embodiment of the present invention; In a base station apparatus for resource allocation in a wireless communication system, if a control channel region is included in a data channel region indicated by resource allocation information of a data channel, a resource region having moved the data channel region by the control channel region is determined. A resource mapper for mapping the data channel to the moved resource region, a control channel mapper for mapping a control channel including the resource allocation information to the control channel region, a signal mapped to the data channel region, And a frequency multiplexer for frequency multiplexing and transmitting the signal mapped to the control channel region.

Apparatus according to another embodiment of the present invention; A terminal apparatus for resource allocation in a wireless communication system, comprising: a control channel receiver for receiving a control channel including resource allocation information of a data channel in a control channel region; and the control channel in a data channel region indicated by the resource allocation information If the region is included, the controller includes a controller for determining a resource region for moving the data channel region by the control channel region, and a resource inverse mapper for receiving a data channel in the moved resource region.

According to the disclosed embodiment of the present invention, a base station multiplexes a control channel and a data channel having different basic units of resource allocation in scheduling a frequency-controlled control channel and a data channel, and allocates resources of the control channel. Resource waste is prevented by shifting the data channel in consideration of the location where the information and control channel are actually transmitted. Through this, the base station can obtain high resource efficiency and can schedule more terminals using the smallest control channel transmission. In addition, by using existing control channel information without such additional signaling, it is possible to minimize the change of the base station and the terminal.

1 illustrates a control channel structure of a downlink frame in an OFDM system;
2 is a diagram illustrating resource allocation of a control channel and a data channel in an OFDM system;
3 is a diagram illustrating mapping of resource allocation information and data channel resources transmitted through a control channel;
4 is a diagram illustrating resource allocation of a control channel and a data channel according to an embodiment of the present invention;
5 is a diagram illustrating multiplexing of data and control channels according to an embodiment of the present invention;
6a, b, c and 7a, b, c illustrate examples of moving a data channel region according to an embodiment of the present invention;
8 is a flowchart illustrating a transmission procedure of a base station according to an embodiment of the present invention;
9 is a flowchart illustrating a receiving procedure of a terminal according to an embodiment of the present invention;
10 is a block diagram of a base station transmission apparatus according to an embodiment of the present invention;
11 is a block diagram of a terminal receiving apparatus according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, 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. Therefore, the definition should be based on the contents throughout this specification.

Hereinafter, a technique for performing efficient resource allocation in a wireless communication system will be described. The following description will be made based on the LTE system and the LTE-A system, but the present invention can be applied equally to other wireless communication systems to which the base station scheduling is applied.

OFDM transmission is a method of transmitting data using a multi-carrier, that is, a multi-carrier, in which a plurality of multi-carriers having parallel symbols and serially orthogonal relations with each other. In other words, it is a type of multi-carrier modulation that modulates and transmits a plurality of sub-carrier channels.

Such a system using a multicarrier modulation scheme was first applied to military high frequency radios in the late 1950s, and the OFDM scheme of overlapping a plurality of orthogonal subcarriers began to develop in the 1970s, but the implementation of orthogonal modulation between multicarriers was implemented. Since this was a difficult problem, there was a limit to the actual system application. However, in 1971, Weinstein et al. Announced that modulation and demodulation using the OFDM scheme can be efficiently processed using a Discrete Fourier Transform (DFT). Also known is the use of guard intervals and the insertion of cyclic prefix (CP) symbols into the guard intervals, further reducing the negative effects of the system on multipath and delay spread. .

Thanks to these technological advances, OFDM technology has been developed for Digital Audio Broadcasting (DAB), Digital Video Broadcasting (DVB), Wireless Local Area Network (WLAN), and Wireless Asynchronous Transmission Mode (Wireless). It is widely applied to digital transfer technologies such as Asynchronous Transfer Mode (WATM). In other words, the OFDM method has not been widely used due to hardware complexity, and recently, various digital signal processing technologies including fast fourier transform (FFT) and inverse fast fourier transform (IFFT) have been used. It is made possible by the development.

The OFDM scheme is similar to the typical frequency division multiplexing (FDM) scheme, but most of all, the orthogonality between a plurality of tones is maintained to obtain optimal transmission efficiency in high-speed data transmission. In addition, the OFDM scheme has high frequency usage efficiency and strong characteristics in multi-path fading, thereby obtaining optimal transmission efficiency in high-speed data transmission.

In addition, the OFDM scheme uses an overlapping frequency spectrum, which makes efficient use of frequency, resists frequency selective fading, resists multipath fading, and inter-symbol interference using protection intervals. It is possible to reduce the influence, to simply design an equalizer structure in hardware, and to be strong in impulsive noise, and thus it is being actively used in a communication system structure.

The factors that hamper high-speed, high-quality data services in wireless communication are largely due to the channel environment. In wireless communication, in addition to the additive white Gaussian noise (AWGN), the channel environment is based on Doppler due to power variation, shadowing, movement of the terminal, and frequent speed changes of the received signal caused by fading. ), Frequent changes due to interference by other users and multi-path signals. Therefore, in order to support high-speed and high-quality data services in wireless communication, it is necessary to effectively overcome the above-mentioned obstacles in the channel environment.

In the OFDM scheme, a modulated signal is located in a two-dimensional resource composed of time and frequency. The resources on the time axis are divided into different OFDM symbols and they are orthogonal to each other. Resources on the frequency axis are divided into different tones (or subcarriers) and they are also orthogonal to each other. That is, in the OFDM scheme, if a specific OFDM symbol is designated on the time axis and a specific tone is designated on the frequency axis, it may indicate one minimum unit resource, which is called a resource element (RE). Different REs have orthogonality to each other even though they pass through a frequency selective channel, so that signals transmitted to different REs may be received at a receiving side without causing mutual interference.

A physical channel is a channel of a physical layer that transmits modulation symbols that modulate one or more encoded bit streams. In Orthogonal Frequency Division Multiple Access (OFDMA) systems, a plurality of physical channels are configured and transmitted according to the purpose of the information string to be transmitted or the receiver. The transmitter and the receiver must promise in advance which RE to arrange and transmit a physical channel. The rule is called mapping.

The LTE system and the LTE-A system, which is an extension thereof, are a representative system in which OFDM is applied to the downlink, and SC-FDMA (Single Carrier-Frequency Division Multiple Access) is applied to the uplink.

1 illustrates a control channel structure of a downlink frame in an OFDM system. The illustrated structure may be supported for compatibility even in LTE-A system.

Referring to FIG. 1, the total downlink (DL) transmission bandwidth 101 is composed of a plurality of resource blocks (RBs) (or physical RBs (PRBs)), and each RB ( 103 is, for example, composed of 12 frequency tones arranged on the frequency axis and 14 OFDM symbols or 12 OFDM symbols arranged on the time axis, and is a basic unit of resource allocation. A subframe 105 including two symbols is shown.One subframe 105 has a length of 1 ms and consists of two slots 107.

Reference signals (RS) 115 and 113 are pre-promised signals transmitted to the terminal for the UE to perform channel estimation. In the LTE system, a common RS (CRS) 115 and a dedicated reference signal are used. A signal (Dedicate RS: DRS) 113 is used. The common reference signal 115 denotes an RS transmitted from ports 0 and 1 of a base station having two antenna ports, and antennas 0, 1, 2 and 3 of a base station having four antenna ports, respectively.

If the number of antenna ports exceeds one, it means using a multi-antenna. The absolute position where the RS is placed on the frequency axis is set differently for each cell, but the relative spacing between the RSs remains constant. That is, the RS of the same antenna port maintains six RB intervals. The reason why the absolute position of the RS is set differently for each cell is to avoid collision between cells of the RS. The number of RSs is different for each antenna port. There are 8 RSs in one RB and subframe for antenna ports 0 and 1, but 4 RSs in one RB and subframe for antenna ports 2 and 3 exist.

Since the common reference signal 115 should be able to be received by all terminals, it is transmitted in the same format in all RBs over the entire downlink band. On the other hand, the dedicated reference signal 113 is a UE-specific reference signal and is transmitted only in the RB to which each terminal is scheduled. In the RB allocated to the terminal not using the dedicated reference signal, the dedicated reference signal may not be transmitted.

Like the common reference signal 115, the dedicated reference signal 117 can use a plurality of antenna ports. Although there are differences depending on the configuration method, the LTE-A system uses the same resource and two scrambling codes on the two antenna ports. This supports a total of eight dedicated reference signals. The dedicated reference signal 117 is transmitted in the data area of the specific PRB 103 allocated to the specific terminal and is not transmitted in the entire downlink band.

In general, the common reference signal is applied when using a single antenna transmission and a time diversity (TD) transmission method for obtaining a frequency or antenna diversity gain, and may be applied to a beamforming technique if necessary. In general, the common reference signal should be able to be received by all users in the cell, and it is important that the signals transmitted through all the terminals can also be received. On the other hand, transmission using a dedicated reference signal mainly uses a beamforming technique to obtain a frequency selective gain. In this case, each terminal can be received with a high signal quality because the signal is transmitted using a frequency resource preferred by each terminal. However, when the channel changes quickly, it is difficult to respond.

On the other hand, the control channel is located at the head of one subframe on the time axis and is allocated to the control channel symbol region 109 composed of a predetermined number of OFDM symbols on the frequency axis. The control channel signal may be transmitted over L OFDM symbols located at the head of the subframe. L may have a value of 1, 2, or 3 in a general case, and may have a value of 2, 3, or 4 when the transmission bandwidth is small. The illustrated control channel symbol region 109 consists of three OFDM symbols.

The control channel region can be dynamically changed for each subframe. If the amount of control channel information required is small enough to transmit a control channel signal with one OFDM symbol, only the first 1 OFDM symbol is used for transmission of the control channel signal (L = 1) and the remaining 13 OFDM symbols are data channel signals. Used for the transmission of. On the other hand, if a large amount of control channel information is required, the number of symbols for the data channel is reduced.

Since the value of L is used as basic information for demapping control channel allocation resources in the control channel reception operation, in particular, information for interleaving the control channel, the terminal cannot recover the control channel when it does not have information about L. . The reason for placing the control channel signal at the beginning of the subframe is to allow the terminal to first determine whether to perform the data channel reception operation by receiving the control channel signal and recognizing whether the data channel signal transmitted to the terminal is transmitted. For sake. Therefore, if there is no data channel signal transmitted to the terminal itself, it is not necessary to receive the data channel signal, thus saving power consumed for the reception operation of the data channel. In addition, scheduling relay can be reduced by receiving the leading control channel faster than the data channel.

The control channel of the LTE system is called a physical dedicated control channel (PDCCH), and the data channel is called a physical dedicated dedicated channel (PDSCH). The PDCCH is a physical channel for transmitting a common control channel and a dedicated control channel. The PDCCH is an allocation for transmitting resource indication or resource allocation (RA) and system information of a data channel. Control information transmitted to the terminal, such as information, power control information, is transported.

The PDCCH is transmitted through a single antenna transmission method when the base station has one antenna, and is transmitted through the TD transmission method when the base station has a plurality of antennas. The channel coding rate of the PDCCH may be set differently according to the channel state of the terminal. Since PDCCH uses Quadrature Phase Shift Keying (QPSK) as a modulation method, it is necessary to change the amount of resources used by one PDCCH to change the channel coding rate. A terminal having a good channel state can apply a high channel coding rate to reduce the amount of resources used. On the other hand, even if the amount of resources used is increased to the terminal in a bad channel state, the reception is possible by applying a high channel coding rate.

The amount of resources consumed by each PDCCH is determined in a unit called a control channel element (CCE). Each CCE is composed of nine resource element groups (REGs). The REG of the PDCCH is disposed in a resource region consisting of a DL transmission bandwidth 101 and a PDCCH symbol region 109 after interleaving with other control channels in order to guarantee frequency diversity and distribute inter-cell interference.

Interleaving is a REG unit of a control channel, and is performed on an REG configured among total control channel resources of a subframe determined by L. Control channel interleaving prevents inter-cell interference caused by using the same interleaving between cells, while at the same time the divers of the REGs of the control channel allocated across one or more symbols are far from the frequency axis. It is done to get city gain. Specifically, the control channel interleaving ensures that REGs constituting the same channel are equally distributed among symbols for each channel, and also includes multiplexing between different control channels.

In the evolved environment assumed in the LTE-A system, it is assumed that more base stations are disposed in one base station area than existing systems, and that base stations of various sizes are arranged. As a result, the number of base stations per unit area increases, and at the same time, the amount of interference increases. The PDCCH configured for distributing inter-cell interference is no longer subjected to the dispersing effect of the interference and receives large interference from a plurality of adjacent cells, thereby reducing the coverage of the UE.

In addition, one base station uses MU-MIMO (Multi-User MIMO) technology or cross-carrier scheduling to schedule more terminals and maximize system performance. Although the number of channels increases, there is a problem that the data channel can no longer be scheduled due to insufficient capacity of the controllable transmission channel. To this end, there is a demand for a new control channel, and as a solution for this, a method of transmitting a control channel using a dedicated reference signal on an existing data channel is required.

In the case of transmitting a control channel through a data channel, interference can be avoided by using different frequency resource regions between base stations, and since a dedicated reference signal can be used, a control channel for a plurality of terminals on the same resource using a plurality of antennas. Can greatly increase the control channel capacity.

This new control channel is referred to as Enhanced PDCCH (ePDCCH). The base station notifies the terminal of some PRB resources 117 in the overall DL transmission bandwidth 101 through higher signaling, and transmits the ePDCCH through some PRBs of the informed region. Information on the resource region occupied by the ePDCCH is notified to the terminal through higher signaling. The terminal receives both the ePDCCH and its associated PDSCH in the ePDCCH symbol region 111 on the time axis, and the ePDCCH and PDSCH are transmitted together by frequency multiplexing.

2A and 2B illustrate resource allocation of an ePDCCH and a PDSCH in an OFDM system. As shown, resource allocation for the ePDCCH and PDSCH is made in units of PRBs.

Referring to FIG. 2A, the PRB 201 includes an ePDCCH, and within one PRB 201, the ePDCCH is a time interval 211 after the PDCCH located first on the time axis and some frequency intervals of the PRB 201 ( 209 may be occupied. Likewise, referring to FIG. 2B, the PRB 215 includes a PDSCH, and within one PRB 215, the PDSCH is similar to the ePDCCH, and the time interval 217 and the PRB 215 after the PDCCH first located on the time axis. May occupy the entire frequency interval 218).

In the LTE system, the control channel (PDCCH) does not have a specific coding rate, and the amount of information compared to resources is determined using a unit called an aggregation level. Possible aggregation levels are 4 and 8 for common control channels and 1, 2, 4 and 8 for dedicated control channels. The unit of aggregation is CCE. One CCE consists of a total of 36 resource elements (REs). A total of four allocation candidate positions are available among 16 contiguous CCEs for a consolidation level 4, and contiguous for a cohesion level 8. A total of two allocation candidate positions are available among the 16 CCEs.

Therefore, the base station can transmit a common control channel to the six areas in total. Dedicated control channels have different demodulation times depending on the level of aggregation, where aggregation levels 1 and 2 have a total of six demodulations and aggregation levels 4 and 8 have a total of two demodulations. The CCEs that actually perform demodulation for each aggregation level may or may not be the same. Table 1 below shows an example of a configuration of a control channel search space in an LTE system.

Search space S _k ^(L) Number of  PDCCH candidates M ^(L) Type Aggregation level  L Size  [ in CCEs ] UE-specific One 6 6 2 12 6 4 8 2 8 16 2 Common 4 16 4 8 16 2

As an example, the control channel transmitted in the actual logical resource region between the base station and the terminal is determined by Equation 1 below.

Where m = 0, ..., M ^(L) -1 and i = 0, ..., L-1. L is the aggregation level, N _{CCE, k} means the total number of CCEs in the k-th subframe. According to Equation 1, the terminal derives a CCE index indicating a CCE to perform a bled demodulation to search for a control channel transmitted by a base station. Y _k is a random variable for distributing control channels for each user so as not to collide with each other in the entire control channel region.

However, in the case of a common control channel, Y _k is set to 0, and all terminals receive the same area. The start of Y _k is a terminal ID and A and D are predetermined constants. For example, A is 39827 and D is 65537.

Therefore, the minimum amount of control channels that can be transmitted is 36 REs occupied by one CCE. For example, when the ePDCCH occupies six subcarriers 209 in the frequency domain and a total of 11 symbols 211 on the time axis, as shown in FIG. 2A, the number of usable REs is 43 in total. 29 REs are available when 4 subcarriers are used in

Considering that the existing control channel was capable of frequency-distributed transmission, it is advantageous for the ePDCCH which uses only some frequency domains to partially increase the number of REs used compared to the existing control channel, so it is preferable to use six subcarriers 209. Do. In the following description, it is assumed that the frequency domain size of the ePDCCH is 6 for convenience, but the present invention can be applied regardless of the frequency domain size of the control channel. Therefore, two or more ePDCCHs having basic units may be transmitted on one PRB.

Also, referring to FIG. 2B, since the basic unit of PDSCH transmission is the PRB 215, the base station should instruct the terminal to transmit data using at least one PRB. Therefore, only one data channel for one terminal may exist on one PRB.

3 illustrates mapping of resource allocation information and data channel resources transmitted through a control channel.

Referring to FIG. 3, data channel allocation to a PRB is made in units of a virtual resource block (VRB) 301. The actual transmission resource is determined by a predetermined mapping relationship between the virtual resource VRB and the actual resource PRB. Resource allocation in the LTE system is largely divided into the same resource allocation for the VRB and PRB and different resource allocation for the VRB and PRB for each slot.

When the ePDCCH 303 including the downlink control channel information on the VRB # X 301 is transmitted using one resource allocation unit and schedules a data channel having four PRBs, the base station determines the VRB # X + 1. Schedule the resource region 307 not including the ePDCCH 303 through the resource allocation information 305 indicating ˜X + 4 or through the resource allocation information 311 indicating VRB # X ˜X + 3. The resource region including the ePDCCH 303 may be scheduled. When scheduling VRB # X + 1 to X + 4 not including the ePDCCH, the remaining resource regions 309 of VRB # X cannot be used as data channels of other terminals.

The remaining resource region 309 may be used for an ePDCCH of another terminal or an uplink control channel for a terminal using the ePDCCH 303.

However, the remaining resource region 309 is used for the ePDCCH of the other terminal, the resource region is separated from the ePDCCH or data channel transmitted using a demodulation reference signal (DMRS) is not assigned to a continuous PRB It is not suitable because it must be sent to. The ePDCCH is transmitted using DMRS, and its associated data channel is also transmitted using DMRS. In order to transmit DMRS, a specific PRB region is selectively used for frequency transmission. However, in order to fill the remaining resource region 309, it is not suitable to transmit an ePDCCH of another terminal to a region different from data.

Therefore, the remaining resource region 309 is preferably used for transmission of an uplink control channel for a terminal having an ePDCCH (303). However, since the uplink control channel does not always exist, the remaining resource regions 309 are likely to be waste. In addition, as the number of UEs using the ePDCCH increases, the remaining resource region 309 also increases.

If the ePDCCH 303 lowers the coding rate of the ePDCCH 303 so that it occupies all of the VRB # 1 301, the remaining resource region 309 may not be wasted, but may not be used for other purposes.

On the other hand, when the transmission resource of the data channel is scheduled to include the PRB 301 through which the ePDCCH 303 is transmitted to prevent the above problem, the base station instructs the terminal up to the VRB index X ~ X + 3 but transmits the actual data channel. 313 uses only 3.5 PRBs. In this case, the base station cannot use resources corresponding to about 12% and eventually needs to increase a coding rate of 12%, which causes a problem of decreasing the coverage of the terminal or reducing the transmittable data.

Therefore, in order to maximize resource efficiency and prevent capacity reduction, the base station should be able to transmit a data channel regardless of the existence of the ePDCCH, and at the same time, it is necessary to minimize the resource waste caused by the ePDCCH.

In a preferred embodiment of the present invention described below, when an ePDCCH is present in a scheduled data channel resource and the ePDCCH does not occupy the entire PRB, the base station selects the data channel in the resource region shifted by the ePDCCH. send. When the ePDCCH exists in the control channel region and the ePDCCH does not occupy the entire indicated PRB, the terminal attempts to receive a data channel in the resource region shifted by the resource occupied by the ePDCCH.

4 illustrates resource allocation of a control channel and a data channel according to an embodiment of the present invention.

Referring to FIG. 4, the ePDCCH 403 is located in the VRB # X 401 and occupies only a part of the VRB # X 401. If the scheduled data channel region indicated by the resource allocation information 405 transmitted through the ePDCCH 403 does not include the VRB # X 401 where the ePDCCH 403 is located, the base station determines resource allocation information 405. Data channel is actually transmitted in VRB # X + 1 ~ X + 3 indicated by. The terminal determines that the resource region 407 of the actual data channel is the same as that indicated by the resource allocation information 405, and attempts to receive (ie, demodulate and decode) the data channel in the resource region 407.

On the other hand, if the scheduled data channel region indicated by the resource allocation information 411 includes the VRB # 4 401 where the ePDCCH is located, the base station replaces the VRB # X to X + 3 indicated by the resource allocation information 411. The ePDCCH 403 actually transmits a data channel in the resource region 413 shifted by the transmitted resource region. The terminal determines that the actual data channel is transmitted in the resource region 413 at the position 415 moved by the resource region to which the ePDCCH 403 is transmitted in VRB # X to X + 3 indicated by the resource allocation information 411. An attempt is made to receive a data channel in the resource zone 413.

Since resource allocation as shown in FIG. 4 supports two methods of transmitting an actual data channel in RB units and moving and transmitting an ePDCCH transmission resource, uplink control of a resource 309 that cannot be used as in FIG. 3 is performed. It can be assigned to data channels as well as channels. Therefore, the resource efficiency can be increased, the area occupied by the control channel can be minimized, and since it can be applied without changing the existing control channel, there is an advantage that there is no change of the terminal.

5 illustrates multiplexing of data and control channels according to an embodiment of the present invention. Here, an example of resource allocation when transmitting control channels and data channels for two users, UE1 and UE2 to five VRBs, that is, VRB # X to X + 4 is illustrated.

Referring to FIG. 5, an ePDCCH 505 for UE1 is transmitted through a partial region of VRB # X 501, and an ePDCCH 507 for UE2 indicates a partial region of VRB # X + 2 503. Is sent through. The base station allocates VRB # X + 3, X + 4 through the resource allocation information 519 for the UE2, and the UE2 receives the ePDCCH 507 at the VRBX + 2 503, and the resource allocation information 519 is An actual data channel is received in the resource region 521 of the indicated VRB # X + 3, X + 4.

On the other hand, since the ePDCCH 507 for the UE2 is being transmitted in the VRB # X + 2 503, and the UE1 cannot know whether or not the ePDCCH 507 is transmitted for the UE2, the base station determines resource allocation information 515 for the UE1. ) To assign VRB # X, X + 1. In this case, when UE1 receives a data channel only in resource regions 509 corresponding to 1.5 PRBs according to the related art, the remaining resource regions 511 may not be used in both UE1 and UE2. In addition, since UE1 needed resources as much as two PRBs, in order to transmit a data channel through 1.5 PRB resources 509, the coding rate is increased or the amount of transmission data is reduced, thereby reducing the transmission performance of the data channel. Done.

In contrast, according to the embodiment shown in FIG. 4, the base station transmits a data channel through the resource region 517 moved from the resource region indicated by the resource allocation information 515 by the resource region occupied by the ePDCCH 505. Occation,

Since UE1 knows that the ePDCCH 505 exists in the resource region allocated by the resource allocation information 515, the UE1 determines that a data channel is actually transmitted through the moved resource region 517, and thus the movement. The received data channel in the resource region 517. Accordingly, UE1 can use two RB resource regions as data channels, thereby ensuring the reception performance and coverage of UE1.

In addition, the embodiment of the present invention ensures the beamforming gain and the frequency selective gain by allocating consecutive frequency resources for the control channel and the data channel to each terminal, and can efficiently transmit data channels without wasting resources. Can be used.

The UE first obtains resource allocation information by demodulating and decoding the ePDCCH, and determines whether its own ePDCCH is included in the data channel region indicated by the resource allocation information. If the ePDCCH is included in the data channel region, the terminal receives the data channel in the resource region shifted according to a predetermined rule.

6 (including FIGS. 6A, 6B, and 6C) and 7 (including FIGS. 7A, 7B, and 7C) illustrate a data channel region when an ePDCCH is included in an allocated data channel region according to an embodiment of the present invention. It shows examples of moving.

Referring to FIG. 6A, an ePDCCH 603 for a UE (ie, UE1) is transmitted from a VRB # X 601, and resource allocation information 605 of the ePDCCH 603 is set to VRB # X, X + 1. Indicates a data channel region. The terminal determines that the allocated data channel region includes the ePDCCH 603, and receives the data channel in the resource region 607 in which the data channel region is moved by the resource region of the ePDCCH 603. As shown in the figure, when the ePDCCH 603 is transmitted in the lowest RB index of the data channel region, the UE moves the data channel region in a direction in which the RB index is higher.

Referring to FIG. 6B, the ePDCCH 609 for the UE is transmitted in VRB # X + 2, and the ePDCCH 609 is located at the highest RB index of the data channel region indicated by the resource allocation information 611. Similarly, the terminal moves and expands the data channel region indicated by the resource allocation information 611 in the direction in which the RB index increases, thereby determining the resource region 613 in which the actual data channel is transmitted. In detail, the ePDCCH 609 is transmitted in the rear half region of VRB # X + 2, and the resource allocation information 611 indicates VRB # X + 1, X + 2. The data channel is then actually transmitted in the front half of VRB # X + 1 and VRB # X + 2 and in the front half of VRB # X + 3.

Referring to FIG. 6C, an ePDCCH 615 for a UE is transmitted in VRB # X + 2, and the ePDCCH 615 is located at an intermediate RB index of the data channel region indicated by the resource allocation information 617. Similarly, the terminal determines the resource region 619 in which the actual data channel is transmitted by moving and expanding the data channel region indicated by the resource allocation information 617 in a direction in which the RB index increases. Specifically, the ePDCCH 615 is transmitted in the front half region of VRB # X + 2, and the resource allocation information 617 indicates VRB # X + 1, X + 2. The data channel is then actually transmitted in the rear half of VRB # X + 1 and VRB # X + 2 and in the front half of VRB # X + 3.

In the embodiments shown in FIGS. 6A, 6B and 6C, the case in which the data channel region is moved in the direction in which the RB index is increased has been described. However, it is apparent that the same may be applied to the movement in the direction in which the RB index is decreased. The movement rule of the data channel region is preferably applied equally to all terminals, and may be predetermined by a system operator and designer, or may be equally notified to every terminal in a cell through system information, or not for each terminal through higher signaling. Can be.

In another embodiment to be described later, the UE obtains resource allocation information by demodulating the ePDCCH, determines whether there is an ePDCCH transmitted to the resource allocation information, and also determines the location of the RB including the ePDCCH. If the location of the ePDCCH is located in the middle of the data channel region, the terminal does not move the data channel region and receives it as indicated by the resource allocation information. On the other hand, if the location of the ePDCCH is located where the RB index of the data channel region is low, the terminal receives the data channel by shifting the data channel region toward the higher RB index. In addition, when the location of the ePDCCH is located where the RB index of the data channel region is high, the terminal receives the data channel by shifting the data channel region toward the lower RB index.

Here, the position where the RB index is low may mean a VRB having the lowest RB index or VRBs having a predetermined number of lower RB indexes. Similarly, the position where the RB index is high may mean a VRB having the highest RB index or VRBs having a predetermined number of higher RB indexes. The middle of the data channel region means at least one VRB except for a predetermined low RB index position and a predetermined high index position.

Referring to FIG. 7A, an ePDCCH 703 for a UE (that is, UE1) is transmitted from a VRB # X 701, and resource allocation information 705 of the ePDCCH 703 is set to VRB # X, X + 1. Indicates a data channel region. The terminal determines that the allocated data channel region includes the ePDCCH 703, and receives the data channel in the resource region 707 in which the data channel region is moved by the resource region of the ePDCCH 703. When the ePDCCH 703 is located at the lowest RB index of the data channel region, the UE moves the data channel region in a direction in which the RB index is high. Specifically, the ePDCCH 703 is transmitted in the front half region of VRB # X, and the resource allocation information 705 indicates VRB # X, X + 1. The data channel is then transmitted in the back half region of VRB # X and in the front half region of VRB # X + 1 and VRB # X + 2.

Referring to FIG. 7B, the ePDCCH 709 for the UE is transmitted in VRB # X + 2, and the ePDCCH 709 is located at the highest RB index of the data channel region indicated by the resource allocation information 711. . Then, the terminal determines the resource region 713 where the actual data channel is transmitted by extending the data channel region indicated by the resource allocation information 711 in the direction of decreasing the RB index. In detail, the ePDCCH 709 is transmitted in the rear half region of the VRB # X + 2, and the resource allocation information 711 indicates the VRB # X + 1, X + 2. The data channel is then actually transmitted in the rear half of VRB # X and in the front half of VRB # X + 1 and VRB # X + 2.

Referring to FIG. 7C, the ePDCCH 715 for the UE is transmitted in VRB # X + 2, and the ePDCCH 715 is located at an intermediate RB index of the data channel region indicated by the resource allocation information 717. The terminal then uses the data channel region indicated by the resource allocation information 717 without any movement or extension. That is, the ePDCCH 715 is transmitted in the front half region of VRB # X + 2, and the resource allocation information 717 indicates VRB # X + 1, X + 2, and the data channel is VRB # X + 1 and VRB #. Transmitted in the back half area of X + 2.

In the embodiment shown in FIGS. 7A, 7B, and 7C, the moving direction of the data channel region is determined differently according to the position of the ePDCCH. Accordingly, the base station can freely adjust the position of the data channel and the control channel of the terminal to allocate the data channel region regardless of the position of the resource waste occurs. In other words, even when a portion of a region where a terminal can use is low, a portion of high frequency, or a portion in which resources are empty is transmitted, all data channels can be moved and transmitted. In addition, if the ePDCCH is included in the data channel region but does not need to be moved, the ePDCCH may be included in the middle of the data channel region to prevent the problem of resource waste.

Resource allocation according to the embodiments of the present invention described above is a bitmap resource allocation, which is a resource allocation scheme supported by LTE and LTE-A systems, a resource allocation for allocating a contiguous PRB as a bitmap, and concatenating PRBs. It can support resource allocation that converts starting point and allocated length into one representative value and indicates, and resource allocation that allocates PRBs spaced at regular intervals and allocates them as bitmaps.

In addition, when downlink scheduling information and resource allocation information (which may be included in downlink scheduling information) for the UE are transmitted through the ePDCCH in the resource allocation, the data channel region indicated by the resource allocation information is used for uplink. ePDCCH is not transmitted. This is because, when the base station transmits the uplink ePDCCH but the terminal fails to receive, it is difficult for the terminal to determine whether the resource allocation of the uplink data channel.

In addition, although the proposed resource allocation is described based on the case in which control information is transmitted through the ePDCCH, the case in which the control information is transmitted through the PDCCH may be applied.

8 is a flowchart illustrating a transmission procedure of a base station according to an embodiment of the present invention.

Referring to FIG. 8, in step 801, the base station dynamically allocates a resource region for a downlink control channel for each subframe within a semi-static pre-allocated resource region and assigns the downlink control channel. It transmits resource allocation information for the data channel. In step 803, it is determined whether the resource allocation region (i.e., data channel region) of the data channel indicated by the downlink control channel is included in the resource region of the downlink control channel. In accordance with one of the embodiments shown in the mapping (shifted) to the resource region (shifted) to be transmitted. In step 805, the base station allocates an uplink control channel such that a control channel for uplink is not included in the resource allocation region of the data channel.

9 is a flowchart illustrating a reception procedure of a terminal according to an embodiment of the present invention.

Referring to FIG. 9, in step 901, the UE receives an uplink control channel and a downlink control channel from a base station for each subframe in a quasi-statically allocated resource region, performs blind demodulation, and moves down from the downlink control channel. Obtain resource allocation information of the link data channel. In step 903, the terminal determines whether the control channel received by the terminal is included in the resource allocation region (i.e., the data channel region) indicated by the resource allocation information. In such a case, the terminal determines whether the terminal is shown in FIG. Receive a data channel in the moved resource region according to one of these.

10 illustrates an apparatus for transmitting a base station according to an embodiment of the present invention.

Referring to FIG. 10, the PDCCH generator 1005 and the ePDCCH generator 1007 generate a PDCCH signal and an ePDCCH signal containing corresponding control information as needed. The ePDCCH signal 1009 is mapped to the corresponding resource region by the ePDCCH mapper 1009. The scheduler 1003 performs scheduling on the data channel with reference to scheduling information included in at least one of the PDCCH signal and the ePDCCH signal, and transmits the result to the resource mapper 1013.

The PDSCH generator 1001 generates a data channel signal containing data for a terminal, and the reference signal generator 1011 generates a common reference signal for all terminals and / or a dedicated reference signal for a specific terminal. do. The resource mapper 1013 refers to the scheduling information delivered from the scheduler 1003 and the mapping information of the ePDCCH delivered from the ePDCCH mapper 1009, and corresponds to a resource region corresponding to the data channel signal and the common / dedicated reference signal. Maps to. In this case, the data channel signal may be mapped to the resource region moved from the resource region indicated by the resource allocation information in the scheduling information according to the resource position to which the ePDCCH is mapped.

The frequency division multiplexer (FDM) 1015 performs frequency multiplexing on a data channel signal and a reference signal mapped from the resource mapper 1013 and an ePDCCH mapped signal transmitted from the ePDCCH 1009. do. A Time Division Multiplexer (TDM) 1017 time multiplexes the signal transmitted from the frequency multiplexer 1015 and, if present, the PDCCH signal delivered from the PDCCH 1005. The TX processor 1019 transmits the output signal from the time multiplexer 1017 to the terminal through a predetermined transmission process.

11 illustrates a receiving device of a terminal according to an embodiment of the present invention.

Referring to FIG. 11, a signal received through a reception processor 1101 of a terminal is separated into a signal of a control channel region and a signal of a data channel region through a time division demultiplexer 1101. The resource demapper 1109 separates the reference signal 1115 from the signal of the control channel region and transmits the reference signal 1115 to the channel estimator 1121. The PDCCH receiver 1107 demodulates the PDCCH signal to extract coded control information, and the control channel decoder 1123 decodes the coded control information to obtain control information.

The frequency demultiplexer 1105 separates the frequency resource unit through the signal in the data channel region, and the resource demapper 1111 separates the PDSCH signal and the ePDCCH signal from the frequency resource unit signal from the frequency demultiplexer 1105. . The ePDCCH signal is demodulated through the ePDCCH receiver 1117 and decoded through the control channel decoder 1123. The PDSCH signal is demodulated by PDSCH receiver 1113 and provided to PDSCH decoder 1119. The controller 1125 provides the PDSCH decoder 1119 with information necessary for decoding the data channel using control information obtained from the PDCCH and / or the ePDCCH.

In this case, the controller 1125 may control the data from the data channel region to the control channel region according to the position of the data channel region indicated by the resource allocation information in the control information obtained from the control channel decoder 1123 and the control channel region occupied by the ePDCCH. The moved resource region is determined, and the resource demapper 1111 controls to receive the PDSCH signal in the moved resource region.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited by the illustrated embodiments, but should be determined by the scope of the appended claims and equivalents thereof.

Claims (24)

In the resource allocation method in a wireless communication system,
Transmitting a control channel including resource allocation information of a data channel in a control channel region;
If the control channel region is included in the data channel region indicated by the resource allocation information, determining a resource region in which the data channel region is moved by the control channel region;
And transmitting a data channel in the moved resource region.
The method of claim 1, wherein the determining
And determining a moving direction of the data channel region according to the position of the control channel region within the data channel region.
The method of claim 1, wherein the determining
And when the control channel region is located at a low resource block index within a predetermined range of the data channel region, moving the data channel region in a direction in which the resource block index is high.
The method of claim 1, wherein the determining
And when the control channel region is located at a high resource block index within a predetermined range of the data channel region, moving the data channel region in a direction in which the resource block index is lower.
The method of claim 1, wherein the determining
And when the control channel region is located at an intermediate resource block index within a predetermined range of the data channel region, determining the same resource region as the data channel region.
The method of claim 1,
And allocating a control channel region for uplink so as not to be included in the moved resource region.
In the resource allocation method in a wireless communication system,
Receiving a control channel including resource allocation information of a data channel in a control channel region;
If the control channel region is included in the data channel region indicated by the resource allocation information, determining a resource region in which the data channel region is moved by the control channel region;
And receiving a data channel in the moved resource region.
The method of claim 7, wherein the determining process,
And determining a moving direction of the data channel region according to the position of the control channel region within the data channel region.
The method of claim 7, wherein the determining process,
And when the control channel region is located at a low resource block index within a predetermined range of the data channel region, moving the data channel region in a direction in which the resource block index is high.
The method of claim 7, wherein the determining process,
And when the control channel region is located at a high resource block index within a predetermined range of the data channel region, moving the data channel region in a direction in which the resource block index is lower.
The method of claim 7, wherein the determining process,
And when the control channel region is located at an intermediate resource block index within a predetermined range of the data channel region, determining the same resource region as the data channel region.
8. The method of claim 7, further comprising receiving an uplink control channel in a control channel region for uplink allocated not to be included in the moved resource region.
A base station apparatus for resource allocation in a wireless communication system,
If the control channel region is included in the data channel region indicated by the resource allocation information of the data channel, the resource region in which the data channel region is moved by the control channel region is determined, and the data channel is mapped to the moved resource region. Resource mapper,
A control channel mapper for mapping a control channel including the resource allocation information to the control channel region;
And a frequency multiplexer for frequency multiplexing and transmitting the signal mapped to the data channel region and the signal mapped to the control channel region.
The method of claim 13, wherein the resource mapper,
And a movement direction of the data channel region is determined according to the position of the control channel region within the data channel region.
The method of claim 13, wherein the resource mapper,
And when the control channel region is located at a low resource block index in a predetermined range of the data channel region, the base station apparatus moving the data channel region in a direction in which the resource block index is high.
The method of claim 13, wherein the resource mapper,
And when the control channel region is located at a high resource block index in a predetermined range of the data channel region, the base station apparatus moving the data channel region in a direction in which the resource block index is lower.
The method of claim 13, wherein the resource mapper,
And when the control channel region is located at an intermediate resource block index within a predetermined range of the data channel region, determining the same resource region as the data channel region.
The method of claim 13,
And a scheduler for allocating a control channel region for uplink so as not to be included in the moved resource region.
A terminal device for resource allocation in a wireless communication system,
A control channel receiver for receiving a control channel including resource allocation information of a data channel in a control channel region;
A controller for determining a resource region in which the data channel region is moved by the control channel region when the control channel region is included in the data channel region indicated by the resource allocation information;
And a resource reverse mapper for receiving a data channel in the moved resource region.
The method of claim 19, wherein the controller,
And a movement direction of the data channel region is determined according to the position of the control channel region within the data channel region.
The method of claim 19, wherein the controller,
And when the control channel region is located at a low resource block index in a predetermined range of the data channel region, moving the data channel region in a direction in which the resource block index is high.
The method of claim 19, wherein the controller,
And when the control channel region is located at a high resource block index within a predetermined range of the data channel region, moving the data channel region in a direction in which the resource block index is lower.
The method of claim 19, wherein the controller,
And when the control channel region is located at an intermediate resource block index within a predetermined range of the data channel region, determining the same resource region as the data channel region.
20. The terminal apparatus of claim 19, further comprising a control channel receiver for receiving an uplink control channel in a control channel region for uplink allocated not to be included in the moved resource region.

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