KR101494643B1 - A Method for transmitting and receiving control channel in a wireless communication system and an apparatus thereof - Google Patents

Abstract

The present invention relates to a method and apparatus for transmitting and receiving control channels in a wireless communication system, and in particular, to a control channel transmission method for a subframe in which multiple carriers are used, A physical carrier format indicator (PCFICH) having a channel allocation indicator (L) indicating that a data control channel is not transmitted; A subcarrier generation step of generating subcarriers of the one subframe including the subchannel, and a step of transmitting the one subframe, the method comprising: a control channel transmission method of a wireless communication system, Method and a transmitting / receiving apparatus.

PDCCH, PDSCH, PCFICH

Description

TECHNICAL FIELD [0001] The present invention relates to a method and apparatus for transmitting and receiving a control channel of a wireless communication system,

And more particularly, to a method and apparatus for transmitting and receiving control channels of a wireless communication system for efficiently utilizing radio resources.

The OFDM transmission scheme is a scheme for transmitting data using a multi-carrier, that is, a multi-carrier, in which a symbol sequence input in series is parallelized and a plurality of multi- Carriers, that is, a plurality of sub-carrier channels, and transmits the modulated signals.

The system employing such a multi-carrier modulation scheme was first applied to a military high frequency radio in the late 1950s, and the OFDM scheme for overlapping a plurality of orthogonal subcarriers began to develop from the 1970s, but the implementation of orthogonal modulation This was a difficult problem, so there was a limit to the practical application of the system. However, in 1971, Weinstein et al. Announced that it is possible to efficiently process the modulation and demodulation using the OFDM scheme using DFT (Discrete Fourier Transform), and the technology development for the OFDM scheme has been rapidly developed. Also, it is known that a guard interval is used and a cyclic prefix (CP) is inserted in a guard interval, so that the negative influence of the system on multipath and delay spread can be further improved. .

Due to such technological advancement, the OFDM technique can be applied to digital audio broadcasting (DAB), digital video broadcasting (DVB), wireless local area network (WLAN) and wireless asynchronous transmission mode (WATM : wireless asynchronous transfer mode). In other words, the OFDM scheme is not widely used due to hardware complexity. Recently, various digital signal processing techniques including a fast Fourier transform (FFT) and an inverse fast Fourier transform (IFFT) It has become feasible.

The OFDM scheme is similar to a conventional frequency division multiplexing (FDM) scheme. However, the OFDM scheme maintains orthogonality among a plurality of tones, thereby achieving optimal transmission efficiency in high-speed data transmission. The OFDM scheme is also characterized in that it has good frequency utilization efficiency and is resistant to multi-path fading, thereby achieving optimal transmission efficiency in high-speed data transmission.

Another advantage of the OFDM scheme is that frequency use is efficient, frequency selective fading is robust, multipath fading is strong, and inter-symbol interference (ISI: inter symbol interference can be reduced and it is possible to design the equalizer structure in hardware easily and it has the advantage of being strong against impulse noise so that it is being utilized in a communication system structure.

Factors that hinder high-speed, high-quality data services in wireless communications are largely due to the channel environment. In the wireless communication, the channel environment may include a Doppler (Doppler) signal, which is generated due to a fading phenomenon other than additive white Gaussian noise (AWGN), a power change of a received signal, shadowing, Doppler effects, interference from other users and multi-path signals, and the like. Therefore, in order to support high-speed and high-quality data services in wireless communication, it is necessary to effectively overcome the obstacles to 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 distinguished by different OFDM symbols and they are orthogonal to each other. The resources on the frequency axis are distinguished by different tones, which are also orthogonal to each other. That is, in the OFDM scheme, when a specific OFDM symbol is designated on the time axis and a specific tone is designated on the frequency axis, it can be pointed to a minimum unit resource, which is referred to as a resource element (hereinafter referred to as "RE"). Different REs are orthogonal to each other even though they pass through a frequency selective channel, so that signals transmitted in different REs can be received at the receiving side without mutual interference.

A physical channel is a channel of a physical layer for transmitting a modulation symbol modulating one or more encoded bit streams. In the Orthogonal Frequency Division Multiple Access (OFDMA) system, a plurality of physical channels are configured and transmitted according to the use of the information sequence to be transmitted or the receiver. The transmitter and the receiver have to make a promise in advance to which RE the physical channel is to be transmitted and which rule is referred to as mapping (hereinafter, "mapping").

The LTE system is a typical system in which the OFDM system is applied to the downlink. Recently, research on the development of an LTE-A (Long Term Evolution-advance) system is underway. The LTE-A system is expected to be composed of various scenarios. For example, the LTE-A system can use an improved OFDM symbol structure suitable for an indoor channel environment. In an indoor environment, This is because the impact of the multi-path is small. In this case, unlike the existing LTE system, the length of the CP can be made small to increase the frequency efficiency of a symbol, and a different symbol structure than that of the existing LTE system can be introduced.

The LTE-A system is basically an LTE system because it is an evolved structure of the LTE system. Therefore, all the control channels used in the LTE system can be reused. In addition, since LTE-A terminals have a larger ratio than LTE-A terminals in the initial stage of LTE-A system introduction, the LTE-A base station should configure the system so that transmission and reception of LTE terminals are not hindered. An LTE-A base station installed indoors can configure a dedicated subframe for LTE-A terminal only for higher frequency efficiency when an LTE-A terminal is connected. In this case, the existing LTE terminal can receive the LTE-A dedicated subframe, but can not recover the data. Therefore, when there is an LTE-A dedicated subframe in the current LTE system control channel configuration, the LTE terminal can not know information about the LTE-A dedicated subframe, and it is impossible to distinguish each subframe.

1 is a view for explaining a structure of a downlink frame according to a conventional technique.

Referring to FIG. 1, reference numeral 111 denotes a control channel for a control channel in all carriers. In this manner, when different control channels (PCIFICH, PHICH, PDCCH) are transmitted for each subframe of each carrier, the control channel information is included in all the carriers 101, 103, 105, 107 and 109, It is necessary to demodulate the control channel. That is, since the UE must receive control channels of all carriers, the complexity increases by the number of carriers.

For example, when the base station indicates carrier 1 (101) and carrier 4 (104) in one subframe as an LTE-A dedicated subframe, the base station transmits the subframe # 2). ≪ / RTI > At this time, when communication is performed using multiple carriers through the carrier 1 and the carrier 4, the terminal first receives the PCFICH, PHICH, and PDCCH, which are the control channels of the carrier 1, to receive the data of the carrier 1, Receives the PCFICH, PHICH, and PDCCH of the carrier 4 and receives the data. At this time, the LTE-A UE increases the number of control channel demodulation attempts by the number of multiple carriers used in comparison with the LTE UEs that can not use multiple carriers. Therefore, the number of unnecessary attempts increases and it increases proportionally as the number of multiple carriers used increases.

Reference numeral 113 denotes transmission of the control channel in the representative carrier when the carrier 1 (101) is the representative carrier. Even if the control channel is transmitted in the representative carrier, the PCFICH and PHICH must be transmitted in all carriers.

However, as shown at reference numerals 127, 129, 131, and 133, the size of the control channel region is defined as the value of the PCFICH transmitted from the representative carrier, and the three symbols of the four carriers 103, 105, 107, (135), and a total of 20 symbols are transmitted without PDCCH. In this case, the area of the PDCCH of all the carriers is determined according to the PCFICH value reported by the representative carrier, so that the PDCCH area of the other carrier is empty without transmitting data and wasted. That is, there is a problem that radio resource is wasted because a data control channel without information occupies an unnecessary band 135.

That is, when the control channel is transmitted over the entire bandwidth, the demodulation attempt of the UE does not increase, but the efficiency of the control channel is worsened as compared with the number of users, The channel reception performance can not be guaranteed.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a method and apparatus for providing a subframe for an LTE-A terminal or an LTE- A control channel transmission / reception method and apparatus of a wireless communication system that does not perform a reception operation and does not receive a control channel of some carriers and uses the region for data transmission when the LTE-A terminal requires multiple carrier transmission .

According to an aspect of the present invention, there is provided a control channel transmission method for a subframe in which multiple carriers are used, the method including: transmitting a control signal including a physical data control channel (PDCCH) A representative carrier generating step of generating a representative carrier of the one subframe, and a Physical Control Format Indicator Channel (PCFICH) having a channel allocation indicator (L) indicating that a data control channel is not transmitted. A subcarrier generation process of generating subcarriers of one subframe, and transmitting the one subframe.

Wherein the step of generating a dependent carrier includes a control format indicating channel having a channel allocation indicator (L) indicating that a data control channel is included in the dependent carrier when a data control channel is required to be transmitted to one dependent one of the dependent carriers And the one dependent carrier is generated.

According to another aspect of the present invention, there is provided a method for receiving a control channel in a subframe using multiple carriers, the method comprising the steps of: A representative carrier receiving step of receiving a PDCCH and a physical downlink shared channel (PDSCH) of a representative carrier in accordance with the channel allocation indicator L; Includes a step of receiving a data channel in a data control channel region of a subordinate carrier when the subordinate carrier does not have a data control channel according to the channel allocation indicator (L) of the control format indicating channel in the subordinate carrier.

In the subordinate carrier receiving process, when control channel information is present in the subordinate carriers according to the channel allocation indicator (L) of the control format indicating channel in the subordinate carrier, the control channel and data channel are discriminated according to the channel allocation indicator (L) And receiving the data.

According to an aspect of the present invention, there is provided a control channel transmission apparatus for a wireless communication system in a subframe using multiple carriers, A control format indication channel (PCFICH) processing unit for setting a channel allocation indicator (L) for identifying a data channel area; A data control channel (PDCCH) processor for generating a data control channel according to the channel allocation indicator L; A data channel (PDSCH) processor for generating a data channel according to the channel allocation indicator L; And a scheduler for allocating a data control channel of all carriers to the representative carrier of the one subframe and controlling the control format indicating channel processing unit not to allocate a data control channel to the dependent carrier.

Wherein the scheduler controls the control format indicating channel processing unit to allocate a data control channel to a dependent carrier when the data control channel is transmitted to one of the dependent carriers.

According to another aspect of the present invention, there is provided a control channel receiving apparatus for a radio communication system in a subframe in which multiple carriers are used, A control format indicator channel (PCFICH) receiver for extracting a channel allocation indicator L; A data control channel (PDCCH) receiver for receiving a data control channel according to a channel allocation indicator (L) extracted from a representative carrier of the one subframe; And a data channel (PDSCH) receiving unit for receiving a data channel in a data control channel region of a slave carrier when a data control channel is not present in a slave carrier according to a channel allocation indicator (L) extracted from a slave carrier of the one subframe .

If the data control channel is present in the dependent carrier according to the channel allocation indicator (L) extracted from the subcarrier of the one subframe, the data control channel receiver receives the data control channel according to the channel allocation indicator (L) And receiving the data.

According to the present invention, when the LTE-A terminal transmits and receives in multiple carriers, the control channel region between the carriers is limited to reduce the reception complexity of the terminal and the limited region is used for data transmission The frequency efficiency can be increased. In addition, unnecessary reception of the control channel is not performed, so that the power consumption of the terminal can be reduced. In addition, in transmitting and receiving the subframe dedicated to the LTE-A system, the LTE terminal can be distinguished from the existing LTE system subframe using the existing channel. In addition, the LTE terminal and the LTE-A terminal can simultaneously operate the LTE-A base station, minimizing the influence on the scheduling.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the same configurations of the drawings denote the same reference numerals as possible whenever possible.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, I will do it. In the following description of the present invention, 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.

Although the LTE system is described herein as an example, the present invention can be applied to other wireless communication systems to which base station scheduling is applied without adding or subtracting it.

2 is a diagram for explaining a subframe structure of a downlink frame according to an embodiment of the present invention.

The total transmission bandwidth 209 is composed of N _RB resource blocks (hereinafter referred to as "RBs"). Each RB 227 includes 12 tones 237 arranged in the frequency axis and 14 OFDM Symbol 239 and is a basic unit of resource allocation. One subframe 211 has a length of 1 ms and is composed of two slots 241.

Reference signals (RS) 233, RS1 229, RS2 231, and RS3 235 are signals that are promised by the MS to the BS so that the MS can perform channel estimation. Means the RSs transmitted from the antenna ports 0, 1, 2, and 3, respectively. If the number of antenna ports is two or more, it means that multiple antennas are used.

If only one transmission antenna port is used, RS0 233 is used for data transmission, RS1 229 is not used for transmission, and RS2 231 and RS3 235 are used for data or control signal symbol transmission. Also, if two transmit antenna ports are defined, RS0 233 and RS1 229 are used for data transmission and RS2 231 and RS3 235 are used for data or control signal symbol transmission.

The absolute position of the RE on which the RSs are arranged 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 the 6RE interval, and the interval between the RS0 233 and the RS1 229 and the interval between the RS2 231 and the RS3 235 remain 3RE intervals. The reason why the absolute position of the RS is set differently for each cell is to avoid the inter-cell collision of the RS.

On the other hand, the control channel signal is located at the head of one subframe on the time axis. In FIG. 2, reference numeral 213 denotes an area where a control channel signal can be located.

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. When there is only a small amount of control channels and only one OFDM symbol is sufficient to transmit the control channel signal, only one OFDM symbol at the head is used for control channel signal transmission (L = 1) and the remaining 13 OFDM symbols are used for data channel signal transmission do.

When the control channel signal consumes two OFDM symbols, only the first two OFDM symbols are used for control channel signal transmission (L = 2), and the remaining twelve OFDM symbols are used for data channel signal transmission.

When all 3 OFDM symbols are used due to a large amount of control channel signals, the first 3 OFDM symbols are used for control channel signal transmission (L = 3), and the remaining 11 OFDM symbols are used for data channel signal transmission.

L value is used as basic information for demapping the control channel in the receiving operation, and the control channel can not be recovered if it is not received.

When the subframe is MBSFN (Multi-Media Broadcast over a Single Frequency Network), L is 2 and MBSFN is a channel for transmitting broadcasting information.

The reason for placing the control channel signal at the head of the subframe is to determine whether the terminal should first perform the data channel reception operation by receiving the control channel signal and recognizing whether or not the data channel signal transmitted thereto is transmitted. Therefore, if there is no data channel signal to be transmitted to itself, it is not necessary to receive the data channel signal, and hence the power consumed in the data channel signal receiving operation can be saved.

The downlink physical control channel defined in the LTE system includes a Physical Format Indicator Channel (PCFICH) 101, a Physical Hybrid ARQ Indicator Channel (PHICH) 121 and a Physical Uplink Indicator Channel , A data control channel (PDCCH) 115, and the like.

The PCFICH is a physical channel for transmitting CCFI (Control Channel Format Indicator) information. CCFI is a control channel allocation indicator, that is, information composed of 2 bits to indicate "L" value. Since the number of symbols allocated to the control channel must be received and received prior to receiving the CCFI, the PCFICH is a channel that all terminals must first receive in the subframe except for the case where the downlink resources are fixedly allocated. Since L is not known before the PCFICH is received, the PCFICH must be transmitted in the first OFDM symbol. The PCFICH channel is divided into 16 subcarriers and transmitted over the entire band (201, 203, 205, 207).

The PHICHs 221, 223, and 225 are physical channels for transmitting a downlink ACK / NACK signal. The terminal receiving the PHICHs 221, 223, and 225 is a terminal that is in the process of transmitting data in the uplink. Therefore, the number of PHICHs is proportional to the number of terminals in data transmission in the uplink. PHICH is transmitted in the first OFDM symbol (L _PHICH = 1) or over three OFDM symbols (L _PHICH = 3). L _PHICH is a parameter that is defined for each cell. When a cell size is large, it is difficult to transmit PHICH using only one OFDM symbol. The configuration information of the PHICH (the amount of the used channel, L _PHICH ) informs the UE of the initial access to the cell to all terminals through the PBCH (Primary Broadcast Channel). The PHICH is transmitted to the designated location for each cell in the same manner as the PCFICH. Therefore, the PHICH can receive PBCH information when it is connected to a cell and acquires PBCH information regardless of other control channel information.

The PDCCH 115 is a physical channel for transmitting data channel allocation information or power control information. The PDCCH can set the channel coding rate differently according to the channel state of the receiving terminal. Since the PDCCH uses quadrature phase shift keying (QPSK) as a modulation scheme, it is necessary to change the amount of resources used by one PDCCH in order to change the channel coding rate. And a high channel coding rate is applied to a terminal having a good channel state so that the amount of resources used can be reduced. On the other hand, for a terminal having a bad channel state, even if the amount of resources used is increased, a high channel coding rate can be applied for reception. The amount of resources consumed by the individual PDCCHs is determined by a unit called a control channel element (hereinafter referred to as "CCE"). The CCE is composed of a plurality of resource element groups (REGs) 237. The REG of the PDCCH is allocated to the descendant control channel resources via the interleaver for diversity guarantee.

REG 237 is a basic unit of control channel resources constituting CCE, PCFICH, and PHICH. The PCFICH and the PHICH use a fixed amount of resources and determine the amount of resources as a set of REGs in order to facilitate multiplexing with the PDCCH and transmission diversity. One PCFICH is configured using N _{PCFICH REGs,} and one PHICH is configured using N _{PHICH REGs} . If N _PCFICH = 4 and N _PHICH = 3, then PCFICH uses 16 RE and PHICH uses 12 RE.

The PHICH applies a code domain multiplexing (CDM) technique to multiplex multiple ACK / NACK signals. In one REG, eight PHICH signals are CDM-multiplexed in the real part and the imaginary part, respectively, and are repeatedly arranged as many as N _{PHICHs in} order to obtain the frequency diversity gain, and are arranged so as to be arranged as far as possible on the frequency axis. Therefore, 8 or fewer PHICH signals can be constructed using N _PHICH REGs. To configure more than eight PHICH signals, another N _PHICH REG shall be used.

After the amount and allocation of the resources of the PCFICH and the PHICH are determined, the scheduler sets the L value. Based on this value, the excluded physical control channel is mapped to the REG of the allocated control channel and interleaving is performed to obtain the frequency diversity gain do.

Interleaving is performed on the total REG of the subframe defined by L in the REG unit of the control channel. The output of the interleaver of the control channel prevents the inter-cell interference due to the use of the same interleaver among the cells, and at the same time, the REGs of the control channels allocated over one or a plurality of symbols are separated from the frequency axis, So that a city gain can be obtained. Also, it is ensured that the REGs constituting the same channel are distributed evenly among the symbols for each channel.

Next, a downlink frame having the above-described subframes according to an embodiment of the present invention will be described. 3 is a view for explaining a DL frame having subframes according to an embodiment of the present invention.

3 shows a part of a downlink radio frame when a subframe of the LTE system and a subframe of the LTE-A system are transmitted from one base station to the multiple carriers 301, 303, 305, 307 and 309.

As shown, LTE subframes 331, 333, 335, 337, 339, 355, 357, 359, 361 and 363 and LTE-A subframes 341, 349, 343, 345, , 351, 353, 365, 367, 369, 371, 373, 375, 377, 379).

The LTE-A subframe may exist at an arbitrary position but can not be transmitted in the downlink subframe numbers 0 (311) and 5 (321). This is because the LTE terminal must be able to access the cell in order for the LTE terminal and the LTE-A terminal to coexist, and the basic channel for accessing the cell is transmitted in the subframe numbers 0 311 and 5 311.

Meanwhile, in the case of the uplink according to the embodiment of the present invention, the LTE terminal or the LTE-A terminal or the LTE and LTE-A terminals can be transmitted in a specific subframe according to the result of the scheduler. That is, in the case of the uplink, an LTE-A dedicated subframe can be used by the LTE terminal.

It is assumed that the position of the LTE-A dedicated subframe proposed by the present invention is transmitted to the LTE-A terminal through the upper signal and the LTE terminal does not recognize the LTE-A dedicated subframe and thus indicates the MBSFN subframe .

When PHICH and uplink transmission are required among downlink control channels, uplink scheduling information is configured to be able to receive both LTE and LTE-A terminals in all subframes.

That is, even in the case of the MBSFN subframe, the PHICH and uplink scheduling information can be received by both LTE and LTE-A terminals. This is because an arbitrary terminal can be transmitted in an arbitrary subframe in the uplink subframe as described above.

First Embodiment

4 is a view for explaining a subframe using multiple carriers according to an embodiment of the present invention.

Referring to FIG. 4, according to an embodiment of the present invention, when transmitting a control channel having a structure using multiple carriers, a control channel 413 is transmitted to a representative carrier 401, and a PDCCH region (413 to 421).

According to the conventional technique, the LTE-A dedicated subframe is instructed to the MBSFN subframe by the LTE terminal, so the PCFICH of the subframe excluding the representative carrier should be indicated as "2 ". However, resources are wasted by attempting to blind decoding all the UEs up to the second symbol of the corresponding subframe. Therefore, in one embodiment of the present invention, the L value of the PCFICH is set to "4 ", and the PDSCH is transmitted to the area excluding the PCFICH and the PHICH. When the PCFICH is set to 4, all the UEs stop receiving the corresponding subframe and can receive the PHICH regardless of the PCFICH by the previously scheduled uplink scheduling information.

Therefore, even if the BS transmits the PCSCH to the PDCCH region, the UE does not attempt to receive the PDCCH. In addition, since the LTE-A terminal also reports the scheduling information of all the carriers in the representative carrier, there is no further reception operation occurring in the multi-carrier transmission.

In the case of the control channel structure for transmitting the PDCCH to the representative carrier, the base station can instruct the LTE-A terminal not only to the LTE-A subframe information but also representative subframe information for each subframe index in each radio frame. The PDCCH is transmitted only in the subframe designated in this manner, and all the LTE-A terminals can receive the control signal from the representative carrier. The representative carrier may indicate different subframes by higher signaling, but it may inform the UE of the lowest carrier index or the highest carrier among the corresponding LTE-A subframes.

Table 1 below illustrates a gain according to a transmission channel transmission method according to an embodiment of the present invention.

[Table 1]

2 carriers 3 carriers 4 carriers 5 carriers benefit 7.1% 9.5% 10.7% 11.4%

Table 1 shows the gain versus spectral efficiency of transmitting a PDCCH (3 symbol) to each carrier when each carrier has the same bandwidth. The gain does not take into account the overhead of PCFICH and PHICH. That is, in the case of reference numeral 412, the number of additional reception attempts to receive the PDCCH in the dependent carriers other than the representative carrier increases in proportion to the number of multiple carriers to be transmitted. On the other hand, according to embodiments of the present invention, such as reference numeral 413, this additional receiving attempt can be reduced.

Meanwhile, as an exceptional case of the first embodiment, if a terminal connected to a carrier transmitting through multiple carriers does not use multi-carrier transmission, the base station should also consider transmitting and receiving uplink and other control channel information. In this case, the BS sets the PCFICH of the corresponding subframe to 2 and transmits the result. At this time, since the terminal uses the control information of the representative carrier in the actual PDSCH, the starting point of transmission of the PDSCH is max {2, L}.

A control channel transmission method of a base station according to an embodiment of the present invention will be described. 5 is a flowchart illustrating a control channel transmission method according to an embodiment of the present invention.

Reference numerals 503, 525, and 527 denote that steps 505 to 523 are repeated for each subcarrier that the base station desires to transmit.

The BS determines in step 505 whether the subframe of the carrier to be transmitted is an MBSFN subframe.

If it is determined in step 505 that the MBSFN subframe is not an MBSFN subframe, step 537 is performed.

In step 533, the BS determines and maps the PCFICH value (L) using the scheduling information, and maps the PHICH in step 535. Then, the BS maps the PDCCH to the (L-1) th symbol in step 537 and maps the data channel (PDSCH) from the Lth symbol in step 539.

In step 507, the BS determines whether the subframe to be transmitted is a representative carrier. At this time, if it is a representative carrier, the process proceeds to step 517, and if not, the process proceeds to step 511.

In case of the representative carrier, in step 517, the base station determines the L value of the PCFICH using the scheduling information of the multiple carriers. In step 519, the base station maps the PHICH to the corresponding area. In step 521, the BS maps a control channel (PDCCH) to the (L-1) th symbol and maps a data channel (PDSCH) from the Lth symbol in step 523. FIG.

If the representative carrier is not a representative carrier, the base station determines the L value of the PCFICH to be 4 in step 511. Then, the base station maps the PHICH in step 513. Then, in step 515, the BS maps the data channel (PDSCH) from the 0th symbol regardless of the L value of the PCFICH of the representative carrier corresponding to the corresponding subcarrier. In this manner, when the control channel is transmitted using the representative carrier, only the data channel is transmitted to the subframes of other carriers other than the representative carrier.

A method of receiving a control channel of a UE according to a first embodiment of the present invention will now be described. 6 is a flowchart illustrating a control channel receiving method according to an embodiment of the present invention.

In FIG. 6, it is assumed that a terminal receives a system information block (SIB) from a corresponding base station and knows an MBSFN subframe location. It is also assumed that the representative carrier of the LTE-A terminal is carrier k (carrier k).

The UE determines in step 605 whether the current subframe is an MBSFN subframe. At this time, if the current subframe is an MBSFN subframe, the terminal proceeds to step 607. If the current subframe is not an MBSFN subframe, the terminal proceeds to step 649. [

If the current subframe is not an MBSFN subframe, the terminal receives the PCFICH of the current subcarrier camped in step 649 and extracts the L value. In step 651, the UE receives the PDCCH and the PHICH according to the L value. In step 653, the UE receives the PDSCH with reference to the PDCCH starting from the Lth symbol according to the extracted L value (step 649). Then, the process proceeds to step 655.

If the current subframe is an MBSFN subframe, the terminal proceeds to another process according to the case of the LTE terminal and the LTE-A terminal in step 607. [ That is, in the case of the LTE terminal, the procedure proceeds to step 645, and in the case of the LTE-A terminal,

In case of the LTE terminal, the terminal receives the PCFICH in step 641 and extracts the L value. At this time, the terminal determines whether the L value extracted in step 643 is "2 ". If the L value is 2, the UE receives the PDCCH and the PHIC, and proceeds to step 645 to receive the PDCCH and the PHICH. On the other hand, if the L value is not 2, the terminal proceeds to step 655.

That is, if the current subframe is an MBSFN in steps 645 to 643, the LTE UE receives the PCFICH L value from the connected carrier j, receives PDCCH and PHICH up to L-1 when the L value is 2, 2, the reception of the current subframe is stopped.

If the current subframe is an MBSFN subframe and the terminal is an LTE-A terminal, the terminal changes the reception frequency to a carrier (carrier k), which is a representative carrier in step 609, and then receives the PCFICH to extract an L value. And receives the PDCCH and the PHICH according to the L value extracted from the PDCCH.

Steps 613, 629, and 631 of the original show the process of receiving a subframe according to each carrier according to the PDCCH received in step 611. FIG. That is, the terminal confirms the sub-frames from the carrier 1 to the carrier M, including the representative carrier.

In step 615, the UE determines whether the corresponding carrier is a representative carrier.

If it is determined in step 615 that the mobile station is not a representative carrier, the MS receives the PCFICH in step 617 and receives the PHICH in step 619. Then, the MS determines in step 621 whether the L value of the received PCFICH is "2 " (step 617). In this case, if the L value is 2, if there is a transmission resource allocated to the corresponding subframe in step 623, the terminal compares the PCFICH value of the current carrier with the L value of the representative carrier to obtain a higher number of L The PDCCH is received up to the (L-1) th symbol and the PDSCH is received from the Lth symbol. On the other hand, if it is determined in step 621 that the L value is not 2, the UE receives the PDSCH from the 0th symbol if there is a transmission resource allocated to the UE in the corresponding subframe in step 625. Here, the UE can know whether there is a transmission resource allocated to the UE through the PDCCH received in step 611.

If it is determined in step 615 that the corresponding carrier is a representative carrier, the UE receives a control channel from the L symbol to the L-1 symbol in step 627, and receives the data channel from the L symbol.

In step 655, the UE receives the next subframe for all carriers and performs the above-described operation.

Second Embodiment

A control channel transmission method according to another embodiment of the present invention will be described. 7 is a view for explaining a subframe using multiple carriers according to another embodiment of the present invention.

According to another embodiment of the present invention, scheduling information may be transmitted using a carrier other than a representative carrier among carriers used for multi-carrier transmission. At this time, the amount of the control channel of the corresponding subframe is fixed to 2 (723) regardless of the PCFICH value L of the representative carrier.

In this case, according to the embodiment of the present invention, even if the PCFICH of the subframe transmitted to the corresponding carrier is set to "2 ", since the actual transmitted PDSCH uses the control information of the representative carrier, Accordingly, a transmission start point of the PDSCH and a PDCCH transmission region are defined. However, since the representative carrier can schedule a large number of UEs, and the L value is proportional to the number of scheduled users, the carrier in which the PCFICH is actually set to 2 is very likely to transmit without using the third symbol.

According to another embodiment of the present invention, in the case of the carriers 707 and 723 in which the PCFICH is set to "2 ", in order to prevent waste of resources occurring in this case, L-2, i.e., up to symbol # 1, and data can be used starting from the Lth symbol, thereby preventing waste.

A control channel transmission method of a base station according to another embodiment of the present invention will now be described. 8 is a flowchart illustrating a control channel transmission method according to another embodiment of the present invention.

Reference numerals 803, 841, and 843 denote that steps 805 to 523 are repeated for each subcarrier that the base station desires to transmit.

The BS determines in step 805 whether the subframe of the carrier to be transmitted is an MBSFN subframe. If it is determined in step 805 that the MBSFN subframe is not an MBSFN subframe, step 833 is performed.

In step 833, the base station determines and maps the L value of the PCFICH using the scheduling information, and maps the PHICH in step 835. Then, in step 837, the BS maps the PDCCH to the (L-1) th symbol and maps the data channel PDSCH from the Lth symbol in step 839. [

In step 807, the BS determines whether the subframe to be transmitted is a representative carrier. At this time, if it is a representative carrier, the process proceeds to step 823; otherwise, the process proceeds to step 811.

In the case of the representative carrier, in step 823, the base station determines the L value of the PCFICH using the scheduling information of the multiple carriers. In step 825, the base station maps the PHICH to the corresponding area. Then, in step 827, the BS maps the PDCCH to the (L-1) th symbol and maps the PDSCH from the Lth symbol in step 829.

If it is not a representative carrier, the base station sets the L value of the PCFICH to 2 or 4 in step 811. As described above, when the scheduling information needs to be transmitted using a carrier other than the representative carrier, the L value of the PCFICH is set to 2.

The base station then maps the PHICH in step 813. If the L value is 4, the BS proceeds to step 819. If the L value is 2, the BS proceeds to step 821 according to the L value set in advance (step 811) in step 815. In step 819, since the L value of the PCFICH of the representative carrier is 4, the MS maps the PDSCH from the L-3 symbol. That is, the PDSCH is mapped from the 0th symbol. On the other hand, in step 821, since the L value of the PCFICH of the representative carrier is 2, the MS maps the PDSCH from the L-1 symbol.

A description will now be made of a receiving method of the UE when the mapped channels are transmitted as described above. 9 is a flowchart illustrating a control channel receiving method according to another embodiment of the present invention.

In FIG. 9, as in FIG. 6, it is assumed that the terminal receives an SIB (System Information Block) from the corresponding base station and knows the location of the MBSFN subframe. It is also assumed that the representative carrier of the LTE-A terminal is carrier k (carrier k).

If the UE receives the downlink frame, the UE determines in step 905 whether the current subframe is an MBSFN subframe. If the current subframe is an MBSFN subframe, the UE proceeds to step 907. If the current subframe is not an MBSFN subframe, the UE proceeds to step 953.

If the current subframe is not the MBSFN subframe, the MS receives the PCFICH of the current subcarrier and extracts the L value in step 953. In step 955, the UE receives the PDCCH and the PHICH according to the L value. In step 957, the UE receives the PDSCH with reference to the PDCCH starting from the Lth symbol according to the extracted L value (step 953). Then, the process proceeds to step 959.

On the other hand, if the current subframe is an MBSFN subframe, the terminal proceeds to another process according to the LTE terminal and the LTE-A terminal in step 907. That is, the process proceeds to step 945 in the case of the LTE terminal, and proceeds to step 909 in the case of the LTE-A terminal.

In case of the LTE terminal, the terminal receives the PCFICH in step 945 and extracts the L value. At this time, the terminal determines whether the L value extracted in step 949 is "2 ". If the L value is 2, the UE receives PDCCH and PHICH in step 951, and proceeds to step 959. [ On the other hand, if the L value is not 2, the terminal proceeds to step 959. That is, when the current subframe is the MBSFN, the LTE UE receives the PCFICH L value from the connected carrier j and receives PDCCH and PHICH up to L-1 when the L value is 2. If the L value is not 2 The reception of the current subframe is stopped.

If the current subframe is an MBSFN subframe and the terminal is an LTE-A terminal, the terminal changes the reception frequency to carrier k, which is a representative carrier, in step 909, receives the PCFICH and extracts the L value, And receives PDCCH and PHICH.

Steps 913, 929, and 931 illustrate a process of receiving the carriers of one subframe according to the PDCCH received in step 911. [ That is, the terminal confirms the carrier from Carrier 1 to Carrier M, including the representative carrier.

In step 915, the UE determines whether the corresponding carrier is a representative carrier.

As a result of the determination in step 915, if the mobile station is not a representative carrier, the terminal receives the PCFICH in step 917 and the PHICH in step 919. Then, the terminal determines in step 921 whether the L value of the received PCFICH is "2 " (step 917). If the L value is 2, the MS receives the PDCCH up to the first symbol with reference to the PCFICH value "2 " of the current carrier if there is a transmission resource allocated to the corresponding subframe in step 925, Lt; th > symbol. On the other hand, if it is determined in step 921 that the L value is not 2, the terminal receives the PDSCH from the third symbol when there is a transmission resource allocated to the corresponding subframe in step 923. In steps 923 and 925, the UE can determine whether there is a transmission resource allocated to the UE through the PDCCH received in step 911. [ On the other hand, if it is determined in step 915 that the corresponding carrier is a representative carrier, the terminal receives a control channel from the L symbol to the L-1 symbol in step 927 and receives the data channel from the L symbol.

In step 959, the UE receives the next subframe for all carriers and performs the above-described operation.

The control channel transmission method according to the embodiment of the present invention has been described above. Next, a control channel transmitting and receiving apparatus according to an embodiment of the present invention will be described.

First, a configuration of a control channel transmitting apparatus according to an embodiment of the present invention will be described. 10 is a diagram for explaining a configuration of a control channel transmitting apparatus according to an embodiment of the present invention.

10, a base station control channel transmission apparatus according to an exemplary embodiment of the present invention includes a scheduler 1001, a control format indicator channel (PCFICH) processor 1005, a retransmission indication A channel (PHICH) processing unit 1007, and a data control channel (PDCCH) processing unit 1009. In this case, when configuring the control channel, the base station may further include an RS processing unit 1003 for transmitting a reference symbol (RS), which is agreed with the terminal.

Also, the control channel transmission apparatus according to the embodiment of the present invention further includes a data channel (PDSCH) processing unit 1013 for configuring a data channel. In this case, when configuring a data channel like the control channel, And an RS processing unit 1011 for transmitting a reference symbol (RS).

Also, the transmitter according to the embodiment of the present invention includes a first MUX 1015 for multiplexing the control channels, a second MUX 1017 for multiplexing the data channels, and a multiplexed control channel and data A time domain Mux for multiplexing the channel in the time domain, and a transmission unit Tx for transmitting the multiplexed data and control channel.

The scheduler 1001 determines a mapping rule for each control channel based on multiple carrier transmission information, MBSFN information, the number of PHICHs, and the like, and determines an amount to be used for a symbol of a control channel according to the information. That is, the L value of the PCFICH is determined. Based on the determined L value, the PDCCH processing unit is controlled by selecting whether to use the PDCCH in the corresponding subframe.

In particular, the scheduler 1001 includes a control format indicator channel (PCFICH) processor 1005 and a data control channel (PDCCH) processor (not shown) to allocate the data control channels of all carriers to representative carriers of one subframe using multiple carriers 1013). The scheduler 1001 also controls the control format indicator channel (PCFICH) processor 1005 and the data control channel (PDCCH) processor 1013 so as not to allocate a data control channel to a dependent carrier.

That is, in the case of the representative carrier, the control format instruction channel (PCFICH) processing unit 1005 is controlled to allocate the L value (L = 1 to L = 3) as much as necessary to the PDCCH, And controls the data control channel (PDCCH) The PDCCH processing unit 1013 controls the control format instruction channel (PCFICH) processing unit 1005 so that the L value of the PCFICH of the dependent carrier is set to "4 & ).

On the other hand, when the scheduler 1001 is to transmit a data control channel to one dependent carrier of one subframe using multiple carriers, the scheduler 1001 sets the L value of the PCFICH of the dependent carrier to "2" (PCFICH) processing unit 1005 according to the present invention.

The PDFICH signal of the PDFICH processing unit 1005 is generated, and the L value is generated under the control of the scheduler 1001 at this time. In particular, the PDFICH processing unit 1005 sets the L value of the subframes corresponding to the L value of the representative carrier used in the communication using the multi-carriers to 4 under the control of the scheduler. At this time, if the UE connected to the carrier transmitting through multiple carriers does not use the multi-carrier transmission, it can set the PCFICH of the corresponding subframe to 2 and transmit the uplink and other control channel information.

The PHICH processing unit 1007 collects 8 PHICH signals from the individual PHICH signal generators and generates and outputs CDMs. Here, the PHICH signal is a downlink ACK / NACK signal.

The PDCCH processor 1009 includes a PDCCH signal generator for generating a PDCCH signal transmitted to different mobile stations. The number of CCEs occupied by one PDCCH is determined by the scheduler 1001. [ In addition, under the control of the scheduler 1001, when transmission of a PDCCH is required, interleaving is performed.

Next, a configuration of a control channel receiving apparatus according to an embodiment of the present invention will be described. 11 is a view for explaining a configuration of a control channel receiving apparatus according to an embodiment of the present invention.

11, a control channel receiving apparatus of a terminal according to an embodiment of the present invention includes:

A reception unit (Rx) 1101 for converting a received signal into a baseband signal and outputting the received signal, a time-domain multiplexer 1105 for demultiplexing the baseband signal into a data channel and a control channel, a data channel divided into an RS signal and a PDSCH A third MUX 1107, and a fourth MUX 1109 for outputting a control channel separated into an RS signal, a PHICH, and a PDCCH.

The control channel receiving apparatus of the UE includes a control format indicator channel (PCFICH) receiving unit 1103, a channel estimator 1115, a retransmission instruction channel (PHICH) receiving unit 1117, And a data control channel (PDCCH)

The control channel receiving apparatus of the UE includes a channel estimator 1111 and a data channel (PDSCH) receiving unit 1113 for receiving a data channel.

When the received signal is converted into the baseband signal via the receiving unit 1101, the PCFICH receiving unit 1103 receives the PCFICH and extracts the L value. According to the extracted L value, the area of each control channel and data channel is distinguished.

In particular, the PCFICH receiving unit 1103 receives the PCFICH and extracts the L value. According to the extracted L value, the area of each data control channel and data channel of all carriers is distinguished.

The channel estimator 1115 estimates a channel using the RS signal output from the fourth MUX 1109. The PHICH receiving unit 1117 and the PDCCH receiving unit 1119 receive the PHICH and PDCCH, respectively, according to the channel estimation value estimated by the channel estimator 1115 and the L value of the PCFICH. In particular, according to the L value, the PDCCH receiving unit 1117 selects whether or not to use the PDCCH for the PDCCH use or the defined region, performs a deinterleaver when PDCCH reception is required, And then decodes the PDCCH.

In particular, upon transmission / reception using multiple carriers according to an embodiment of the present invention, the PDCCH receiver 1117 receives the PDCCH from the representative carrier and transmits a resource RE allocated to itself of all carriers including the representative carrier in the received PDCCH, . That is, when multiple carriers are used, the data control channel (PDCCH) receiving unit receives the data control channel in the representative carrier according to the channel allocation indicator (L) extracted from the representative carrier in one subframe. At this time, when the data control channel exists in the dependent carrier according to the channel allocation instruction (L) extracted from the dependent carrier, the data control channel can be received in the dependent carrier according to the channel allocation indicator extracted from the dependent carrier.

The channel estimator 1111 estimates a channel using the RS signal output from the third MUX 1107. The PDSCH receiving unit 1113 can know the area allocated to itself according to the L value of the PCFICH and the reception result of the PDCCH. Accordingly, data is received through the allocated resource RE from the estimated channel value.

Particularly, when transmitting and receiving using multiple carriers according to the embodiment of the present invention, the PDSCH receiving unit 1113 can know resources (RE) allocated to all carriers from the PDCCH received by the data control channel receiving unit of the representative carrier.

While the present invention has been described with reference to several preferred embodiments, these embodiments are illustrative and not restrictive. It will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit of the invention and the scope of the appended claims.

1 is a view for explaining a structure of a downlink frame according to a conventional technique;

2 is a view for explaining a subframe structure of a downlink frame according to an embodiment of the present invention;

3 is a view for explaining a DL frame having subframes according to an embodiment of the present invention;

4 is a diagram for explaining a sub-frame using multiple carriers according to an embodiment of the present invention;

5 is a flowchart illustrating a control channel transmission method according to an embodiment of the present invention.

6 is a flowchart illustrating a control channel receiving method according to an embodiment of the present invention.

FIG. 7 is a diagram for explaining a subframe using multiple carriers according to another embodiment of the present invention; FIG.

8 is a flowchart illustrating a control channel transmission method according to another embodiment of the present invention.

9 is a flowchart illustrating a control channel receiving method according to another embodiment of the present invention.

10 is a view for explaining a configuration of a control channel transmitting apparatus according to an embodiment of the present invention;

11 is a diagram for explaining a configuration of a control channel receiving apparatus according to an embodiment of the present invention.

Claims (8)

A control channel transmission method for a subframe using multiple carriers, A representative carrier generating step of generating a representative carrier of one subframe including a data control channel (PDCCH) of all carriers; A subcarrier generation step of generating subcarriers of the one subframe including a physical format indicator channel (PCFICH) having a channel allocation indicator (L) indicating that a data control channel is not transmitted; And transmitting the one subframe to the control channel. The method according to claim 1, The dependent carrier generation process Generating one dependent carrier including a control format indication channel having a channel allocation indicator (L) indicating that a data control channel is included in the dependent carrier if a data control channel transmission is required for one dependent carrier among the dependent carriers; And transmitting the control channel to the base station. In a control channel reception method of one subframe using multiple carriers, Extracting a channel allocation indicator (L) of a control format indicating channel from a representative carrier of the one subframe; A representative carrier receiving step of separately receiving a data control channel (PDCCH) and a data channel (PDSCH, Physical Downlink Shared Channel) of a representative carrier according to the channel allocation indicator L; And a dependent carrier receiving step of receiving a data channel in a data control channel region of a dependent carrier if there is no data control channel in the dependent carrier according to the channel allocation indicator (L) of the control format indicating channel in the dependent carrier A method for receiving a control channel in a wireless communication system. The method of claim 3, The dependent carrier receiving process Characterized in that a control channel and a data channel are separately received according to a channel allocation indicator (L) of a slave channel when control channel information is present in a slave carrier according to a channel allocation indicator (L) of a control format indicating channel in a slave carrier Receiving a control channel in a wireless communication system. A control channel transmission apparatus of a wireless communication system in a subframe using multiple carriers, A control format indicator channel (PCFICH) processing unit for setting a channel allocation indicator (L) for distinguishing a data control channel and a data channel region according to each carrier of the one subframe; A data control channel (PDCCH) processor for generating a data control channel according to the channel allocation indicator L; A data channel (PDSCH) processor for generating a data channel according to the channel allocation indicator L; And And a scheduler for allocating a data control channel of all carriers to the representative carrier of the one subframe and controlling the control format indicating channel processing unit not to assign a data control channel to the dependent carrier. Control channel transmission device. 6. The method of claim 5, The scheduler And controls the control format indicating channel processing unit to allocate a data control channel to a dependent carrier when a data control channel is transmitted to one of the dependent carriers. A control channel receiving apparatus of a wireless communication system in a subframe using multiple carriers, A control format indicating channel (PCFICH) receiving unit for extracting a channel allocation indicator (L) from a control format indicating channel of each carrier of the one subframe; A data control channel (PDCCH) receiver for receiving a data control channel according to a channel allocation indicator (L) extracted from a representative carrier of the one subframe; And And a data channel (PDSCH) receiving unit for receiving a data channel in a data control channel region of a slave carrier when there is no data control channel in a slave carrier according to a channel allocation indicator (L) extracted from a slave carrier of one subframe Wherein the control channel receiving apparatus comprises: 8. The method of claim 7, The data control channel receiver When a data control channel exists in a slave carrier according to a channel allocation indicator (L) extracted from a slave carrier of one subframe, the data control channel is received according to a channel allocation indicator (L) extracted from the slave carrier A control channel receiving apparatus of a wireless communication system.

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