KR101467786B1 - Method of Allocating Control Channel - Google Patents

Abstract

In this specification, a method of assigning a submap is disclosed. According to an embodiment of the present invention, there is provided a method of allocating a sub-frame, the method comprising: allocating at least one resource region to a sub-frame according to a size of the sub-map; a control header including at least one sub- And transmitting the control header. According to embodiments of the present invention, a downlink control channel can be efficiently allocated in a radio access system having a short-length sub-frame structure.

Sub-frame, sub-frame control header, control channel, sub-map

Description

Method of Allocating Control Channel "

The present invention relates to a subframe structure used in a wireless access system, and relates to a method of allocating a submap and a control channel.

Hereinafter, a general frame structure used in the wireless access system will be described.

1 is a diagram showing a frame structure used in a broadband wireless access system (for example, IEEE 802.16).

Referring to FIG. 1, the horizontal axis of a frame represents an Orthogonal Frequency Division Multiplexing Access (OFDMA) symbol as a unit of time, and the vertical axis of the frame represents a logical number of a subchannel as a frequency unit. In FIG. 1, one frame is divided into data sequence channels for a predetermined period of time by physical characteristics. That is, one frame is composed of one downlink subframe (DownLink Subframe) and one uplink subframe (UpLink Subframe).

At this time, the DL subframe includes one preamble, a frame control header (FCH), a DL-MAP, an UL-MAP, and one or more data bursts data burst). Also, the uplink subframe may be composed of one or more uplink data bursts and a ranging subchannel.

In FIG. 1, a preamble is used as a specific sequence data located in a first symbol of each frame to allow a terminal to synchronize with a base station or to estimate a channel. The FCH is used to provide channel allocation information and channel code information related to the DL-MAP. The DL-MAP and the UL-MAP are media access control (MAC) messages used to inform the UE of channel resource allocation in the downlink and uplink. A data burst indicates a unit of data for transmission from the base station to the terminal or from the terminal to the base station.

A Downlink Channel Descriptor (DCD), which can be used in FIG. 1, indicates a MAC message for informing physical characteristics in a downlink channel, and an uplink channel descriptor (UCD) MAC message for informing the characteristics.

In the case of downlink, referring to FIG. 1, a mobile station detects a preamble transmitted from a base station and synchronizes with a base station. Thereafter, the downlink map can be decoded using information obtained from the FCH. The base station may transmit scheduling information for downlink or uplink resource allocation to the mobile station for every frame (for example, 5 ms) using a downlink or uplink map (DL-MAP / UL-MAP) message.

Using the DL-MAP / UL-MAP structure illustrated in FIG. 1, the base station transmits a MAP message to a Modulation Coding Scheme (MCS) level that all terminals can receive regardless of channel conditions. Thus, unnecessary map message overhead can occur.

For example, terminals near the base station can use a high MCS level (e.g., QPSK 1/2) to encode and decode the message because of the good channel conditions. However, the base station will encode and transmit the MAP message at a low MCS level (e.g., QPSK 1/12) for the UE at the edge of the cell without considering this situation. Therefore, each terminal must always receive a message encoded with the same MCS level regardless of the channel status, and thus unnecessary MAP message overhead may occur.

The unit for allocating resources may be different for each wireless access system. For example, in the IEEE 802.16e system, resource allocation is performed in units of 5 ms. In the 3GPP LTE system, resource allocation is performed with a transmission time interval (TTI) of 1 ms. At this time, there is a MAP for allocating radio resources for each resource allocation unit. Therefore, a dedicated MAP for each UE is needed to increase the frequency efficiency and lower the complexity of the UE.

In 3GPP LTE, this MAP message is defined as a downlink control indicator (DCI) and is transmitted through a physical downlink control channel (PDCCH) channel in the physical layer. In the downlink, there is a channel for transmitting ACK / NACK for the UL-SCH. In 3GPP LTE, the DCI is transmitted through the physical hybrid ARQ indicator channel (PHICH).

2 shows an example of a subframe structure in a 3GPP LTE system.

Referring to FIG. 2, an allocation position of a control channel element (CCE) in a resource block and an allocation position of a reference signal (RS) allocated for channel estimation in each antenna can be known. 2 shows a case where the bandwidth is 1.25 MHz.

In a wireless access system (e.g., 3GPP LTE), multiple CCEs may be transmitted through the first n OFDM symbols of each subframe. Here, the CCE may mean a control information transmission unit. One CCE may be continuously arranged in the time-frequency domain, and may be distributed.

In the 3GPP LTE system, one subframe consists of 14 OFDM symbols. At this time, the first one to three OFDM symbols are used to transmit Physical CFI Channel (PCFICH), PDCCH and PHICH. This is about 7.1% (when one symbol is used) to 21.4% (when three symbols are used) in terms of overhead.

In FIG. 2, a resource unit (RU) is a basic allocation unit having a size of 12 (subcarrier) × 14 (symbol). In the resource block, the first one to three OFDM symbols are used for the control channel. Each control channel is made up of a combination of basic units having a size of 4 × 1 called a Mini Channel Element.

The first symbol is transmitted with a Physical CFI Channel (PCFICH) for transmission of a CFI (Control Frame Indicator). The CFI indicates how many symbols are used as the control channel and consists of a total of four mini CEs. Also, a PHICH for transmitting HARQ ACK / NACK (e.g., A / N mini CE) for uplink data is transmitted to the first symbol. A PDCCH is transmitted to the remaining control channel regions, and the PDCCH is allocated in units of a CCE (Control Channel Element). The CCE can be composed of nine mini CEs. Each CCE is composed of mini CEs at different positions in the frequency axis to obtain frequency diversity.

In the 3GPP LTE system, the PDCCH for each terminal can be detected through blind detection. However, it is very complicated to perform blind detection dozens of times (for example, 40 to 50 times) according to the total number of MAPs. In addition, since blind decoding is to be performed according to the above, there is a problem that the complexity is very high.

Generally, a method of allocating radio resources using a plurality of subchannels on a frequency axis can be applied, in addition to a method of allocating radio resources (e.g., control channels) in a frame on a symbol basis. A method of assigning a control channel on a symbol-by-symbol basis is referred to as a TDM method, and a method of allocating a control channel on a frequency axis-by-subchannel basis is referred to as an FDM method.

A method of allocating radio resources on the frequency axis has the advantage that radio resources of various ratios can be allocated for the control channel. However, in this case, the data channel can be decoded only after the decoding of the control channel is completed. Therefore, a time delay due to this may occur. In a system using a subframe, this time delay may cause a round-trip-time (RTT) of one subframe in the case of serious, and particularly in the case of a TDD system, about one frame (for example, IEEE 802.16e 5 ms) can be generated.

Also, if one OFDM symbol region is all allocated to a submap as in the general TDM scheme, waste of sub-channels not used in a downlink subframe that does not include an uplink submap becomes very severe.

In addition, when a persistent control or a scheduling method for Voice over Internet Protocol (VoIP) is used, the use of submaps can be further reduced. Therefore, if all the OFDM symbols for the submap are allocated in all subframes, serious resource waste may occur.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a new subframe structure.

It is another object of the present invention to provide a method of allocating a submap or an uplink control channel that can be used in a new subframe structure.

In order to solve the above technical problem, a method of allocating a submap and a control channel is disclosed.

According to an aspect of the present invention, a method of allocating a submap includes allocating at least one resource region to a subframe according to a size of a submap, and transmitting a control header including a subframe configuration information and submap information to at least one resource region ) And assigning the submap and transmitting the control header.

In the above method, the one or more resource areas may be configured as control allocation units each including a predetermined resource unit. At this time, it is preferable that each predetermined resource unit included in one or more control allocation units is dispersed in a predetermined order in the entire frequency domain of the subframe.

The allocating of the one or more resource regions may further include rearranging one or more control allocation units included in one or more resource regions in a predetermined order on a predetermined symbol.

In addition, the step of allocating one or more resource areas in the method may further include the step of applying a permutation to a predetermined control allocation unit among the one or more control allocation units. In this case, in the step of reordering, it is preferable that the order of allocation of one or more control allocation units is changed using a predetermined rotation value.

The predetermined resource block included in the control allocation unit in the above method may be located every number of resource blocks in the entire frequency domain of the subframe according to the number of resource blocks included in the control allocation unit.

In addition, the method further includes a step of calculating the total resource requirement of the submap in units of symbols constituted by a predetermined subchannel. In this case, if the total resource requirement of the submap is smaller than one symbol unit, the step of allocating the control header and the submap may include allocating the control header and the downlink submap to the first control allocation unit in a time division multiplexing manner .

In addition, in the step of allocating the control header and the submap in the method, the base station allocates the control header and the downlink submap to the first control allocation unit and allocates the uplink submap to the remaining subchannel area of the first control allocation unit As shown in FIG.

If the uplink submap can not be allocated to the first control allocation unit, the second control allocation unit may be further used to allocate the uplink submap.

The submap allocation method further includes a step of calculating a total resource requirement of the submap in units of symbols constituted by a predetermined subchannel, and if the total resource requirement of the submap is greater than one symbol unit, allocating a control header and a submap A control header and a submap may be allocated to a first symbol of a resource region, a submap may be allocated to a first symbol, and a remaining submap may be allocated to a second symbol of a resource region. At this time, the submap includes the downlink submap and the uplink submap, and the downlink submap may be allocated first and the uplink submap may be allocated to the remaining region.

The present invention has the following effects.

First, according to embodiments of the present invention, it is possible to effectively allocate a downlink control channel in a radio access system having a short-length subframe structure.

Second, by providing a method of efficiently allocating a submap and a control channel in a wireless access system using a subframe structure with a short length, problems of time delay and overhead increase can be solved.

Third, by reducing excessive blind detection times, which is a problem in existing wireless access systems, the problem of increased terminal complexity is alleviated.

According to an aspect of the present invention, there is provided a sub-frame structure used in a wireless access system, and a method of allocating a sub-map and a control channel.

The following embodiments are a combination of elements and features of the present invention in a predetermined form. Each component or characteristic may be considered optional unless otherwise expressly stated. Each component or feature may be implemented in a form that is not combined with other components or features. In addition, some of the elements and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some configurations or features of certain embodiments may be included in other embodiments, or may be replaced with corresponding configurations or features of other embodiments.

Herein, the embodiments of the present invention have been described with reference to the data transmission / reception relationship between the base station and the terminal. Here, the BS has a meaning as a terminal node of a network that directly communicates with the MS. The specific operation described herein as performed by the base station may be performed by an upper node of the base station, as the case may be.

That is, it is apparent that various operations performed for communication with a terminal in a network composed of a plurality of network nodes including a base station can be performed by a network node other than the base station or the base station. A 'base station' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an access point, and the like. The term 'terminal' may be replaced with terms such as User Equipment (UE), Mobile Station (MS), and Mobile Subscriber Station (MSS).

Embodiments of the present invention may be implemented by various means. For example, embodiments of the present invention may be implemented by hardware, firmware, software, or a combination thereof.

For a hardware implementation, the method according to embodiments of the present invention may be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs) , Field programmable gate arrays (FPGAs), processors, controllers, microcontrollers, microprocessors, and the like.

In the case of an implementation by firmware or software, the method according to embodiments of the present invention may be implemented in the form of a module, a procedure or a function for performing the functions or operations described above. The software code can be stored in a memory unit and driven by the processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various well-known means.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention, and are not intended to limit the scope of the invention.

Fig. 3 shows an example of a commonly used frame structure (a) and a frame structure (b) that can be used in the embodiments of the present invention.

3 (a) shows an example of a frame structure used in the 3GPP LTE system. Referring to FIG. 3A, one frame (10 ms) is composed of 10 subframes (1 ms), and one subframe may be composed of two slots.

The base station may generate and transmit a dedicated control channel to allocate transmission / reception resources to each terminal. At this time, each terminal can transmit and receive actual data using the information included in the control channel. The control channel may include resource allocation information, MIMO related information, coding and modulation information, HARQ information, and the like. The information included in the control channel may be defined as downlink control information (DCI). The DCI may be transmitted through a Physical Downlink Control Channel (PDCCH) channel in the physical layer through a special channel coding and multiplexing process.

Referring to FIG. 3 (b), one superframe includes one or more frames, and one frame may include one or more subframes. Also, one subframe may include one or more OFDMA symbols.

The length and number of superframes, subframes, and symbols may be determined by user requirements, system environment, and the like. In the embodiments of the present invention, the term " subframe " is used. Here, 'subframe' means all the lower frame structures generated by dividing one frame into a predetermined length.

The subframe structure used in the embodiments of the present invention can be configured by dividing one frame into one or more subframes. At this time, the number of subframes included in one frame can be determined by the number of symbols constituting the subframe. If one frame is composed of 48 symbols and one subframe is composed of 6 symbols, one frame may be composed of 8 subframes. At this time, if one subframe is composed of 12 symbols, one frame may be composed of 4 subframes.

In FIG. 3 (b), it is assumed that the length of the superframe is 20 ms and the length of the frame is 5 ms. That is, the superframe may be composed of four frames. Further, the frame has a frame structure composed of eight subframes. At this time, one subframe may be configured as six OFDMA symbols.

In FIG. 3 (b), the first subframe of the superframe may include a superframe header. The superframe header may include a broadcast channel (BCH). The superframe header controls and schedules a superframe. Therefore, the super frame header may include various control information in addition to the BCH.

Hereinafter, a structure of a control channel (CCH) applicable to the subframe structure proposed in the present invention will be described.

The control channel considered in the embodiments of the present invention is as follows.

- Downlink (DL) scheduling channel

- uplink (UL) scheduling channel

- ACK / NACK channel for downlink (UL) burst

The downlink and uplink scheduling channels have a logical structure called a submap. Also, the ACK / NACK channel may be configured as an independent control channel. Hereinafter, the submap structure is divided into a physical structure and a logical structure.

<Serv Of the map  Physical channel structure>

4 is a diagram showing an example of a time division method (a) and a frequency division method (b) that can be used in the embodiments of the present invention.

The submap can be allocated in symbol units (time axis) or sub channel units (frequency axis). The case of allocating a submap on a symbol basis is referred to as time division multiplexing (TDM), and the case of allocating on a subchannel basis may be referred to as frequency division multiplexing (FDM).

Table 1 below compares the advantages and disadvantages of the TDM scheme and the FDM scheme.

TDM FDM Advantages - Decoding delay of control information is small.
- When Microsleep is applied, the terminal can turn off RF for about 2 ~ 3 symbol intervals (200ms ~ 300ms) to reduce power consumption.
- It is possible to perform resource allocation of control channel area and data area independently. - The ratio of control channel can be adjusted in various units.
- The unused channel area is relatively small.
- It is possible to operate the control channel area and the data area independently, though it is limited. Disadvantages - The unit of controlling the rate of the control channel among the total subframes is relatively large at 16.667%
- Overall overall overhead.
- There is a control channel region that is not actually used, which leads to loss of frequency efficiency.

Note: Control channel / subframe (ratio):
- 3GPP LTE: 7.1% (1 symbol), 14.3% (2 symbols), 21.7% (3 symbols)
-WiMAX (IEEE 802.16m): 6 symbols / 30DL = 20% - Decoding delay of control information is large
- The memory requirement is large because all input signals must be buffered until control information decoding is completed.
- Microslip can not be applied.
- Frequency diversity gain is relatively low.

5 is a diagram illustrating a method of allocating a subframe control header according to an embodiment of the present invention.

The subframe control header (SFCH) used in embodiments of the present invention may include subframe and submap allocation information. For example, in embodiments of the present invention, the SFCH may include at least one of subframe information, submap information, and message resource allocation information. In addition, the SFCH may optionally include MCS information of the next submap. One SFCH may be allocated per subframe. Of course, the SFCH may be included in the submap, and in this case, the SFCH is allocated only when the submap is allocated.

In Fig. 5, the SFCH may have a fixed MSC level. If the MCS level of the SFCH is changed, the base station can inform the terminal of the changed MCS level using a superframe header (or a super map).

Referring to FIG. 5, the base station may include information on the MCS level of the SFCH in a super frame header and transmit the MCS level information to the UE. At this time, the SFCH for each subframe in the superframe can always maintain the same MCS level. At this time, it is preferable that the MCS level of the SFCH has the lowest MCS level during the superframe (S501).

The base station can transmit the SFCH encoded with the MCS level included in the super frame header to the UE. Since the UE has acquired the MCS information of the SFCH in step S501, it can decode the SFCH (S502).

Also, the base station may transmit a submap including downlink scheduling information and / or uplink scheduling information to the UE. The UE can receive the submap transmitted by the BS using the submap information included in the SFCH decoded in step S502. The UE can receive the downlink data using the downlink scheduling information included in the submap. If the submap includes the uplink submap, the uplink data can be transmitted to the base station using the uplink scheduling information (S503).

Referring to FIG. 5, the BS transmits MCS level information of the SFCH to the MS using the super frame header. In this case, in step S501, the base station may inform the MCS level set information composed of one or more MCS level information that is not MCS level information fixedly used in the corresponding super frame.

When the base station informs the MCS level set information to the UE, the lowest MCS level included in the MCS level set in the superframe can be used as the MCS level of the SFCH. At this time, if the base station desires to change the MCS level of the SFCH, the base station may transmit the MCS level information including the changed MCS level information of the SFCH to the submap (S504).

In step S504, the UE receives the submap including the MCS level information of the changed SFCH, thereby decoding the SFCH using the MCS level of the changed SFCH in the next subframe.

<Sub-Frame Structure>

Hereinafter, the sub-frame structure and sub-map positions that can be used in embodiments of the present invention are shown.

In the embodiments of the present invention, a submap may be allocated for each subframe or may be allocated only to a specific subframe. When a submap is allocated to each subframe, each submap may include resource allocation information of each subframe. If a submap is allocated only to a particular subframe, each submap may contain resource allocation information for one or more subframes.

In the embodiments of the present invention, the concept of subframe grouping may be used. Subframe grouping refers to grouping two or more subframes into one unit. For example, when two subframes are grouped into one, the size of a resource unit (RU) as a resource allocation unit is doubled, but the number of total resource units may not change. Also, if two subframes are grouped into one, the size of the resource unit RU is constant, but the total number of resource units can be doubled. The term resource unit (RU) used in the embodiments of the present invention refers to a resource unit having a predetermined size and may be referred to as a resource block (RB).

The base station can inform the terminal about the subframe to which the submap is allocated by using the superframe header. That is, the base station may include information on a specific period in which a submap exists in the superframe header to inform the terminal. For example, the base station may transmit N to the terminal by including N in a period in which the submap exists in the superframe header. The UE can know that the submap is located in every N subframes through the information.

In addition, the base station can inform the super frame header of the position information of the subframe allocated with the submap in a bitmap format. For example, '1' indicates that a submap exists, and '0' indicates that a submap does not exist. In the embodiments of the present invention, a method of allocating a submap using a bitmap will be used. Of course, submaps can be allocated using a fixed period according to the user's requirements.

Also, in the embodiments of the present invention, the submap may be used as a downlink submap or an uplink submap according to its use. Accordingly, unless the downlink and uplink submaps are distinguished, the submap includes both the downlink submap and the uplink submap.

6 is a diagram showing an example of a subframe structure in a case where the TTI is in units of one subframe.

6, it is assumed that a transmission time interval (TTI) is one subframe. FIG. 6A shows a case where a DL subframe and an UL subframe are symmetrically configured in a TDD system. The base station may include a bitmap of '0b1111 / 0000' in the superframe header and transmit it to the terminal. Therefore, if the terminal confirms the bitmap, the terminal can know which subframe contains the submap.

6 (b) shows a case where the number of DL subframes and UL subframes in the TDD system is asymmetric. The base station may include a bitmap of '0b1111 / 000' in the superframe header and transmit it to the terminal. Accordingly, the UE can know that the submap is located in the first to fifth subframes SF # 0 to SF # 4.

FIG. 6 (c) shows a location where a submap is allocated in the FDD system. The base station includes '0b11111111' in the submap and transmits it to the terminal. When the terminal receives the bitmap from the base station, the terminal can recognize the location where the submap is allocated. That is, when the terminal receives '0b11111111', it can recognize that submaps are allocated to all subframes.

7 is a diagram showing an example of a subframe structure in a case where the TTI is 2 subframe units.

7A shows a case where a base station includes a bitmap of '0b1010 / 0000' in a superframe header and transmits the bitmap to the terminal. Therefore, the submap is located in the first and third subframes SF # 0 and SF # 2. 7B shows a case where the base station includes a bitmap of '0b10101 / 000' in the superframe header and transmits the bitmap to the terminal. Therefore, in FIG. 7 (b), the terminal can recognize that the submaps are located in the first, third and fifth subframes SF # 0, SF # 2 and SF # 4.

FIG. 7A shows an example of a subframe structure that can be used in the embodiments of the present invention, in which the DL subframe and the UL subframe are symmetrically allocated in the TDD format.

In FIG. 7 (a), the DL submap and the UL submap are included in the first downlink subframe SF # 0. At this time, the DL submap of the first downlink subframe includes downlink scheduling information corresponding to SF # 0 and SF # 1, and the UL submap of the first downlink subframe includes SF # 4 and SF # 5 And may include uplink scheduling information. The DL submap of the third downlink subframe includes downlink scheduling information corresponding to SF # 2 and SF # 3, and the UL submap of the third downlink subframe includes SF # 6 and SF # 7. And may include uplink scheduling information.

FIG. 7 (b) shows a case where the DL subframe and the UL subframe are asymmetrically allocated in the TDD format.

In FIG. 7 (b), the DL submap is included in the first downlink subframe SF # 0. At this time, the DL submap of the first downlink subframe may include downlink scheduling information corresponding to SF # 0 and SF # 1. The DL submap of the third downlink subframe includes downlink scheduling information corresponding to SF # 2 and SF # 3, and the UL submap of the third downlink subframe includes SF # 5 and SF # 6. And may include uplink scheduling information. The DL submap of the fifth downlink subframe SF # 4 may include downlink scheduling information corresponding to SF # 4, and the UL submap may include uplink scheduling information corresponding to SF # 7.

7 (c) shows a method of constructing a subframe in the FDD system. In FIG. 7 (c), the allocation position of the submap can be informed to the terminal using the super frame header. That is, the base station may include a bitmap indicating the allocation position of the submap in the superframe header and transmit the bitmap to the terminal.

Referring to FIG. 7 (c), the base station includes '0b10101010' in the superframe header and transmits it to the terminal. When the terminal receives the bitmap, it can be seen that the submaps are allocated to the first, fourth, seventh and eighth subframes (SF # 0, SF # 3, SF # 6 and SF # 7).

In FIG. 7 (c), the DL sub-MAP included in SF # 0 can inform the UE of downlink scheduling information for SF # 0, SF # 1 and SF # 2. The downlink submap included in SF # 3 may inform the UE of downlink scheduling information for SF # 3, SF # 4, and SF # 5. Also, the downlink submaps included in SF # 6 and SF # 7 can inform the UE of downlink scheduling information for SF # 6 and SF # 7, respectively.

The UL sub-MAP (UL Sub-MAP) transmits uplink scheduling information to the UE. In FIG. 7 (c), the same subframe set is shown twice. FIG. 7 (c) shows an FDD scheme for allocating radio resources on a frequency axis. Therefore, the same subframe set is shown once more to clearly indicate the allocation positions of uplink scheduling information for the same subframe.

The uplink submap included in SF # 0 in FIG. 7 (c) indicates uplink scheduling information allocated to SF # 2, SF # 3 and SF # 4, and also indicates information on the uplink control channel. The uplink submap included in SF # 3 indicates uplink scheduling information and uplink control channel information allocated to SF # 5, SF # 6, and SF # 7.

Hereinafter, a method of allocating a submap will be described.

<Variable type TDM  Method>

8 is a diagram illustrating a method of allocating a submap using an SFCH according to another embodiment of the present invention.

Referring to FIG. 8, a base station can transmit a subframe control header (SFCH) including at least one of subframe information and submap information to a terminal (S801).

 In step S801, the subframe information may include information such as the configuration information of the subframe and the number of antennas of the base station. At this time, the subframe configuration information may include at least one of allocation information for a control channel, distribution information of a distributed resource unit (RU), distribution information of a localized resource unit (RU), and subframe grouping information. The submap information indicates the size of the area occupied by the submap. That is, it may include information on the allocation position of the submap and the length of the submap.

In another embodiment of the present invention, submaps may be allocated in a TDM manner. At this time, the position of the submap can be variably allocated. However, it is preferable that the submap is located in the first symbol of the subframe, and when the channel estimation and decoding delay is considered, it is preferable to locate the submap between the first symbol and the third symbol.

In FIG. 8, the BS may transmit a submap including scheduling information to the MS. At this time, the submap may include an uplink submap as well as a downlink submap (S802).

9 is a diagram illustrating a method of variably allocating a submap in a subframe according to an embodiment of the present invention.

FIG. 9 shows a variable TDM (Scarable TDM) scheme, which is proposed to solve a large overhead which is a problem of the TDM scheme. For example, the base station can allocate a submap on a subframe on a symbol basis. However, the submaps are not all allocated to the entire OFDMA symbol area, but are allocated only to a predetermined sub-channel area.

One subframe may be composed of six OFDM symbols. Further, one resource unit (RU) can be defined as 18 (subcarrier) x 6 (symbol). At this time, one subframe may be composed of one or more RUs. A single RU (18 subcarriers x 1 symbol) corresponding to one symbol can be defined as a mini RU (mini RU).

In the embodiments of the present invention, the base station can allocate the submap in a predetermined mini RU unit. A given mini RU can be represented by one Control Allocation Unit (CAU). The number of mini RUs included in the CAU can be changed according to system conditions or user requirements. However, in the following embodiments, three Mini RUs constitute one CAU.

The size of the CAU can be fixed and used in advance by the base station. At this time, the base station can inform the terminal of the size of the CAU using an upper control channel (e.g., a broadcast channel or a super map).

FIG. 9A shows a case where the size of a total submap allocated to one subframe is smaller than the size of one symbol. In FIG. 9 (a), the submap is located in the second OFDM symbol of the subframe. The submap does not occupy all the areas in the first OFDMA symbol but is located in a predetermined sub-channel area. At this time, the submap can be allocated in units of CAU, and the size of the submap can be changed according to the requirements of the user or the channel environment.

FIG. 9 (b) shows a case where the size of the total submap allocated to one subframe is larger than the size of one symbol. FIG. 9 (b) is a scheme that can be applied to increase the accuracy of channel estimation according to the positions of pilot symbols in a subframe.

The variable TDM scheme shares the advantage of the TDM scheme, and overhead due to the low resolution of the TDM scheme can be solved and the problem of resource waste can be solved. In the variable TDM scheme, a submap is allocated on a symbol basis, but the length can be adjusted in units of 1 CAU or 1 subchannel.

The submap allocation method described in FIG. 9 will be briefly described. First, the base station calculates the total resource requirement of the submap in units of OFDMA symbols. If the resource requirement of the entire submap is smaller than one symbol (refer to FIG. 9A), the base station distributes resources in CAU units, and allocates resources to the terminals in the order of SFCH, DL submap, and UL submap.

If the resource requirement of the entire submap is larger than one symbol (refer to FIG. 9 (b)), the base station allocates a DL submap to one symbol. Allocate the DL submap and allocate the UL submap to the remaining space. At this time, if the DL submap is allocated and all the UL submaps can not be mapped to the remaining space, the UL submap is allocated to the RU by adding CAU to the next symbol as necessary.

10 is a diagram illustrating a method of assigning physical resources to logical channels that can be used in embodiments of the present invention.

A method of allocating a physical RU to a logical subchannel will be described. The number of mini RUs included in one OFDMA symbol is 12, and one OFDMA symbol may be composed of 3 CAUs. In this case, the four physically distributed mini RUs are mapped to one logical CAU. At this time, the physical RUs can be mapped to each CAU through various methods. When the total RU is N, if the number of CAUs included in one OFDM symbol is M, the size of CAU can be considered as N / M.

For example, if N = 48 and the total number of CAUs is 12, the size of CAU is 4. As another example, if N = 48 and the size of one CAU is 16, a total of three CAUs are included in one OFDMA symbol.

If the number of CAUs is 3, the CAU can be used in the same manner as a segment applied to the FCH in the IEEE 802.16 system. The segments may be sequentially allocated (in order of 1, 2, or 3) according to the position of the cell, but the allocation order may be different for each cell in consideration of inter-cell interference. For example, if the number of cells is three, the allocation order may be changed as follows. In the first cell type, they may be allocated in the order of 1, 2 and 3. In the second cell type, they may be allocated in the order of 2, 3 and 1. In the third cell type, the segments may be allocated in the order of 3, .

Such differently assigned cell types may be transmitted to the terminal via the superframe header (or superimp) or frame control channel transmitted every 20 ms. The total number of segments may vary depending on bandwidth and system. For example, in the case of the 10 MHz band, it is preferable to configure the segment to 3 to 4.

Depending on the usage of the CAU, three types of resource units (RUs) can be defined. When the size of the CAU is smaller than one OFDMA symbol, as shown in FIG. 9A, there can exist an RU composed of 5 OFDMA symbols and an RU composed of 6 symbols. If the total size of the CAU is larger than one OFDMA symbol, an RU composed of 4 OFDMA symbols and an RU composed of 5 OFDMA symbols can be used as shown in FIG. 9 (b). Of course, the size of the RU may vary depending on the user's requirements or the system environment.

In the variable TDM scheme, the base station can inform all terminals of the total length of the submap for resource block allocation. Accordingly, the base station transmits a sub-frame control header (SFCH) including allocation information of the submap to the terminal. At this time, the SFCH may include other subframe information besides the submap allocation information. The SFCH is located in the first symbol of the subframe and can inform the configuration information of the subframe. The SFCH is preferably defined within the size of one CAU.

The variable TDM scheme proposed in FIG. 10 is particularly effective in a TDD system in which downlink (DL) subframe and uplink (UL) subframes are asymmetrically allocated. For example, the case of DL subframe: UL subframe = 5: 3 will be described. In FIG. 10, the submap is located in the downlink subframe. The submap may include a downlink submap and / or an uplink submap.

In embodiments of the present invention, the DL submap may be located in each downlink (DL) subframe. However, an UL submap may exist only in up to three DL subframes with a given subframe offset. In this case, the sub-map including only the DL sub-map and the sub-map including both the DL sub-map and the UL sub-map are largely different.

That is, there is a difference in allocation positions and sizes of submaps located in three DL subframes and the remaining two DL subframes. If one OFDM symbol region is allocated to the submap as in the general TDM scheme, the waste of the unused sub-channel in the remaining two DL subframes that do not include the uplink submap becomes very severe.

In addition, when a persistent control or a scheduling method for Voice over Internet Protocol (VoIP) is used, the use of submaps can be further reduced. Therefore, if all the OFDMA symbols are used to allocate a submap in each subframe, serious waste of resources may be caused.

Therefore, when the variable TDM scheme is used in the embodiments of the present invention, resource blocks can be appropriately allocated by notifying each terminal of information on the size of each submap. That is, the type of the resource block can be determined according to the size of the submap.

11 is a diagram illustrating an example of a resource allocation method for a TDM control channel region in a subframe.

A basic physical control resource unit (RU) of a control channel for TDM allocation is defined as a mini CRU (Control Resource Unit). A CRU is a kind of RU, and indicates an allocation unit used for a control channel. The mini CRU consists of 18 consecutive subcarriers on the frequency axis. One or more Mini-CRUs can be used to configure one Control Allocation Unit (CAU).

At this time, the CAU represents a sub-channelized basic unit. The CAU may be composed of one or more mini CRUs distributed over the entire frequency band to obtain a diversity gain. The number of CAUs and the size of CAUs can be changed according to the bandwidth or cell type of the system.

If a total of N CAUs are present in one OFDMA symbol, the location of the mini CRUs allocated on the frequency axis of the physical resource is allocated to the logical resource The relationship of the CAU numbers is shown in the following Equation (1).

As shown in FIG. 11, when N = 4, mini-CRUs (1,2,3,4), (1,2,3,4), and so on are assigned to the CAU to which the mini CRUs continuously allocated in the frequency axis are allocated. , (1,2,3,4), and so on.

A CAU that has been allocated as a logical resource may be used as it is, or it may be subjected to various mapping processes. The logical CAUs are newly configured through the mapping process. A SFCH and a subframe map (or a submap) may be allocated to a newly configured logical resource. Of course, the SFCH and the submap may be allocated immediately after being allocated as a logical resource in a physical resource without going through a mapping process.

At this time, the SFCH is located at the beginning of the logical resource. Since the SFCH must receive all the UEs with very high reliability, it is preferable that the SFCHs are allocated so as to have less influence on interference from neighboring cells. The CAU is allocated according to the number of resources required to allocate the control channel in the subframe. The remaining CAUs allocated in the OFDMA symbol may be allocated for a data burst, or may be placed in an empty space to minimize inter-cell interference.

Referring again to FIG. 11, logically assigned CAUs may be mapped in various ways in a cell-specific mapper. At this time, various special mapping methods can be applied to improve the frequency diversity gain. In addition, it is desirable to have a specific structure for each cell in order to minimize the interference received by the SFCH channel.

12 is a diagram showing an example of a cell-specific mapper used in FIG.

12 shows a method of mapping a mini RU assigned to a physical subchannel to a logical subchannel. When a control channel is allocated, a mini RU can be configured in consideration of a diversity gain and a frequency selectivity gain.

The cell specific mapper consists of a cell specific rotation part and a permutation part applied to each CAU. The order of the four CAUs is changed by the cell specific rotation unit. When the rotation value of the cell specific rotation unit is 0, the CAU maintains the order of CAU 0, CAU 1, CAU 2, and CAU 3. When the rotation value is 1, the CAU 1, CAU 2, CAU 3, .

Fig. 12 shows a case where the rotation value is 1. Different rotation values can be used for each cell. In this case, the SFCH is located at a different position from cell to cell. After cell specific rotation is applied, per-carrier permutations may be applied to each CAU. The final logical channel after permutation has a structure spread in the frequency domain to obtain frequency diversity. Preferably, the permutation is applied in a different manner for each cell. That is, a specific logical channel may have a form different from a channel structure used in an adjacent cell through a permutation.

If a particular terminal has good reception performance in a certain frequency band, it may not use permutation in the CAU to continue allocating a specific frequency band. In this case, the subcarriers continuously existing in the frequency axis form a logical channel.

In FIG. 12, permutation is applied to CAU 1 and CAU 2, and permutation is not applied to CAU 3 and CAU 0. The base station can determine whether or not to apply the permutation to each CAU according to the channel condition, and the determination content is transmitted to each terminal through the BCH channel or the SFCH. It is desirable that permutation is applied to the first CAU since SFCH must be received by all terminals.

Also, for efficiency of channel allocation, it is preferable that the CAU applying the permutation and the CAU not applying are continuously present. That is, the CAU located before the change point applies the permutation, and the CAU existing after the change point may not apply the permutation.

Referring again to FIG. 12, the BS may not apply permutation to a specific CAU in order to allocate a mini RU locally in units of CAUs. The base station can allocate a sub-frame control channel in units of a subcarrier x 1 (symbol) mini RU (mini-RU) to a localized CAU.

However, the SFCH is a channel for transmitting configuration information for a subframe, and may be applied to a diversity resource. Therefore, the CAU that is initially generated in the cell of each base station can be used as a diversity resource by applying a permutation. The remaining CAUs can be distributed or localized depending on the situation.

The base station can inform the terminal of allocation information for the CAU through the SFCH or the superframe header (or supermap). The base station can express the allocation information of the CAU using as many bits as the number of CAUs. For example, in the case where one OFDMA symbol includes 12 mini RUs and three mini RUs constitute one CAU, four CAUs may be allocated to one symbol. In this case, if the base station intends to use the last two CAUs as Localized, the base station may indicate the control bits in the SFCH or superframe header (preferably BCH) as '0b0011'. That is, two CAUs (CAU 0 and CAU 3) are shown as concentrated type, and the remaining two CAUs (CAU 1 and CAU 2) are allocated as distributed types.

When the CAU is configured as shown in FIG. 12, beamforming, SFBC, dedicated pilot, or the like can be easily applied to a localized control channel.

< TDM / FDM  Mixed type>

13 is a diagram illustrating a method of allocating submaps in a subframe to a mixed type of TDM / FDM according to another embodiment of the present invention.

FIG. 13 can be applied when submaps are allocated asymmetrically in a subframe. DL submaps and UL submaps may have different requirements in terms of timing. For example, since the DL submap includes the scheduling information of the DL control channel of the corresponding subframe, decoding must be completed until all the OFDMA symbols of the corresponding subframe are received. Therefore, it is advantageous that the DL submap is located in front of the subframe in the TDM scheme. However, since the UL submap has at least two subframes until the UL subframe is transmitted after it is received, the position of the UL submap does not cause a delay of the decoding time.

Therefore, the DL submap and the UL submap can be separately allocated in one subframe. First, a DL submap is allocated as a fixed area within a specific OFDMA symbol by a TDM scheme. At this time, if all of the DL submaps are not allocated within a specific OFDMA symbol, the remaining DL submaps can be allocated using the next OFDMA symbol region.

If a sub-channel area remains after a DL sub-map is allocated to a specific OFDMA symbol area, an UL sub-map may be allocated to the remaining sub-channel areas. In addition, the remaining UL submaps can be allocated using a specific resource block (RU) in the FDM scheme.

In FIG. 13, a submap may be allocated to the first OFDMA symbol of a subframe, but may be variably allocated to another symbol. However, considering the decoding delay, it is preferable that the submap is allocated within the third symbol.

13 (a) shows a method of allocating a submap to a subframe when the size of the total DL submap is smaller than half of a specific symbol and the size of the total submap is smaller than a specific symbol. The base station can allocate the DL submap in the TDM scheme and the UL submap in the FDM scheme using the characteristic resource block. In FIG. 13 (a), a DL submap is configured with six subchannels in one subframe, and an UL submap can be allocated using resource blocks having five OFDM symbols. The remaining space allocated to the submap can be used to measure the amount of interference from other base stations or other terminals.

13B illustrates a method of allocating a submap when the size of the total DL submap is larger than half of a specific symbol and the size of the total submap is smaller than a specific symbol. In FIG. 13 (b), the downlink submap may be allocated in the TDM scheme and the uplink submap may be allocated in the remaining regions.

13 (c) shows a method of allocating a submap when the size of the total submap is larger than the OFDMA symbol. 13 (c) is also similar to the allocation method of FIG. 13 (a) or 13 (b). For example, the DL submap can be first allocated to a specific symbol in the TDM scheme, and the UL symbol can be allocated to the remaining region. If the UL submap can not be allocated to a specific symbol allocated to the DL submap or if the UL submap can not be allocated even after the UL submap is allocated, the UL submap is allocated in an FDM manner using a specific RU composed of five symbols .

In FIG. 13, the DL submap area can use a fixed subchannel size. At this time, it is preferable that the DL submap is allocated in units of six subchannels. In this case, it is possible to select a part in the frequency domain and use it as a control channel. That is, the base station may select only the resource blocks having the odd or even index among the physical resource blocks (RUs) to form the distributed subchannels in order to increase the frequency diversity performance. If the total required amount of the submap exceeds one symbol, the submap may be allocated to one symbol in the TDM scheme, and the resource block may be added in the FDM scheme to allocate the remaining submap information.

In FIG. 13, a base station transmits a control channel using a distributed subchannel using subcarriers of all bands, and a data channel uses a localized subchannel It is possible to efficiently allocate resources.

The hybrid TDM / FDM allocation method described in FIG. 13 is briefly summarized as follows.

One OFDM symbol includes 12 subchannels, and a submap can be allocated in units of 6 subchannels in one OFDM symbol. In addition, the submaps may be allocated in units of CAU described in FIGS. 10 to 12.

If the size of the DL submap does not exceed 12 subchannels (the total frequency area of one OFDM symbol), DL submaps are allocated to the six subchannels in the TDM scheme. At this time, when the size of the DL submap is larger than the size of six subchannels, six additional subchannels can be further allocated.

Allocates the DL submap and allocates the UL submap to the remaining subchannels. At this time, if all of the UL submaps can not be mapped to the remaining subchannels, an UL submap is allocated by newly adding a resource block (RU) in the FDM scheme.

If the DL submap exceeds one OFDM symbol (12 subchannels), the DL submap is allocated to 12 subchannels first. At this time, the DL submap is always allocated in a TDM manner. Allocates a DL submap and allocates an UL submap to a subchannel of the remaining OFDM symbol. If all of the UL submaps can not be mapped to the remaining subchannels, an UL submap is allocated by adding a new resource block.

FIG. 14 is a diagram illustrating a concrete method of allocating a submap in a subframe to a mixed type of TDM / FDM according to another embodiment of the present invention.

The SFCH is located first in the subframe. Also, the SFCH is a channel transmitted to the entire cell, and its contents and size are fixed. The SFCH may include various kinds of information. For example, the SFCH may include resource allocation information for a broadcast channel. The start position and the MCS level of the broadcast channel are fixed by the standard, and the base station only informs the size of the actually allocated resource. However, since the broadcast channel is not always present, allocating the information on the broadcast channel to the SFCH always wastes resources.

 Therefore, in FIG. 14, the TDM type MAP is basically used in the mixed TDM / FDM scheme of the SFCH. However, if the total length of sub-MAPs exceeds one symbol, the uplink sub-map may be allocated in FDM format. Submaps of the FDM type are not always allocated, and their lengths are variable.

In particular, when the allocation ratios of the downlink and uplink subframes are asymmetric (for example, 5: 3 or 6: 2), the UL submap may be transmitted among the downlink subframes, It may not be the case either.

If the UL submap is not transmitted, the BS allocates a resource area for transmitting a broadcast message, a paging message, or an MBS message to the DL subframe. At this time, the base station can inform the terminal of the allocation information through the SFCH.

When the UL submap is transmitted, the base station may not allocate a transmission region for a broadcast message or the like in the DL subframe. At this time, the base station can transmit the allocation information for the frequency domain of the UL submap to the mobile station by including it in the SFCH.

Referring to FIG. 14, one frame is composed of five downlink subframes and three uplink subframes. In FIG. 14, only the DL sub-MAP is allocated to the first sub-frame (SF # 0) and the second sub-frame (SF # # 4), the downlink submap and the uplink submap (UL SubMAP) are all allocated. In FIG. 14, it is assumed that a mixed TDM / FDM scheme is applied as shown in FIG.

At this time, if only the DL submap is allocated to the DL subframe, the BS allocates the SFCH and the DL submap to the first OFDMA symbol of the DL subframe in a TDM manner. In addition, the base station can allocate a broadcast message and a data burst to the remaining OFDMA symbol areas in an FDM manner.

When all DL submaps and UL submaps are allocated in the DL subframe, the BS first allocates the SFCH and DL submaps in the TDM scheme. The UL submap can be allocated to the remaining area, and the UL submap can be allocated to the UL submap when the UL submap is not allocated.

Table 2 below compares the resource allocations according to the general TDM, FDM, variable TDM, and hybrid TDM / FDM schemes for submap allocation.

TDM FDM Variable TDM TDM / FDM mixed type Minimum allocation unit 16.667%
(1 symbol) 2.08%
(1 RU or subchannel) 0.34%
(1RU / 6symbol) 8.33% (basic) + 1.7%
(0.5 symbols + 1RU) If the control channel requirement is 10% of the total, the resource quota 16.667%
(1 symbol) 10.4%
(5 subchannels) 10.2%
(30 units) 20.06%
(1 symbol + 2RU) Wasted resources 6.667% 0.4% 0.2% 0.06% If the control channel requirement is 15% of the total, the resource quota 16.667%
(1 symbol) 16.64%
(5 subchannels) 15.3%
(30 units) 15.133%
(1 symbol + 2RU) Wasted resources 1.667% 1.64% 0.3% 0.13% If the control channel requirement is 20% of the total, the resource quota 33.333%
(2 symbols) 20.8%
(10 subchannels) 20.06%
(59 units) 20.06%
(1 symbol + 2RU) Wasted resources 13.3333% 0.8% 0.06% 0.06%

Table 2 compares four resource allocation schemes in a subframe consisting of 6 OFDMA symbols and 48 RUs. The resolution of the ratio of the control channels occupied by each method and the amount of resources wasted in the specific method can be known. It can be seen that the TDM method consumes a large amount of resource waste. In the case of the variable TDM method and the mixed TDM / FDM method, the resource waste is smallest.

FIG. 15 is a diagram comparing wasteful resources of the TDM scheme, the FDM scheme, the variable TDM scheme, and the mixed TDM / FDM scheme.

In FIG. 15, the horizontal axis represents the ratio of the overhead of the control channel in one subframe, and the vertical axis represents the ratio of the idle subcarriers in one subframe. Referring to FIG. 15, it can be seen that the performance of the mixed TDM / FDM scheme and the variable FDM scheme is good. Of course, the FDM scheme has better performance overhead than the variable TDM scheme, but it is more efficient to use the TDM scheme than the FDM scheme in consideration of diversity and the like. That is, some degree of trade-off between the TDM scheme and the FDM scheme is required.

16 is a diagram illustrating a method of allocating a submap according to another embodiment of the present invention.

Referring to FIG. 16, a BS transmits an SFCH including subframe information to a UE. At this time, the SFCH may include at least one of subframe information, submap information, and message resource allocation information. Optionally, the SFCH may further include MCS information of the next submap header. In addition, one SFCH may be allocated per subframe (S1601).

Table 3 below shows an example of the SFCH format used in another embodiment of the present invention.

Kinds Classification Item Number of bits

SFCH



Subframe information
Distributed Distributed Resource Block (RU) and Distributed Localized Resource Block (RU) distribution information X bit Subframe grouping information X bit The number of antennas of the base station 1 to 2 bits (Group ACK / NACK information) Submap information (size of area occupied by submap) X bit Message resource allocation information (broadcast message, etc.) X bit (MCS information of the next submap header) (1 to 3 bits)

Referring to Table 3, the subframe information may include distribution information of the distributed RU and the centralized RU, grouping information of the subframe, and information on the number of antennas of the base station. In addition, it may further include group ACK / NACK information.

The base station can use the method of transmitting the RU distribution information with the index of the predefined RU distribution, the method of indicating the position of the distributed RU using the bit map, or the method of indicating the distribution ratio of the distributed RU and the centralized RU To the terminal. The grouping information of a subframe indicates the number of subframes grouped when a plurality of subframes are combined and controlled.

The submap information is information indicating the size of the area occupied by the submap. That is, in the variable TDM scheme, the submap information indicates the number of CAUs. In the mixed TDM / FDM scheme, the submap information indicates the number of RUs for UL submap or the location information of RUs (for example, information on which RU is used).

The message resource allocation information is used to allocate a resource allocation and a data message resource for a broadcast message. However, in the case of messages requiring a minimum coding rate, the overhead increases when submaps are separately allocated. Therefore, the broadcast message and the messages requiring minimum coding rate are jointly encoded using joint coding. At this time, only the burst size information may be included in the SFCH after fixing the start position of the burst to transmit the broadcast message. This is called broadcast message resource allocation information.

The message resource is allocated by using a method of notifying the type and number of RUs to be used or fixing the start position where the burst is transmitted and informing only the size information (for example, informing only the size information of the burst in the SFCH) can do. At this time, the size of the RU can be fixed and used.

The MCS information (Modulation & Coding Scheme IE) included in the submap indicates the MCS information of the immediately succeeding submap. The MCS information of the next submap header can indicate whether there is a submap immediately after the SFCH and MCS information about the submap header.

The MCS information included in the submap header indicates MCS information for the submap body. Since the MCS information of the submap header indicates a maximum of 2 to 4 types, 1 to 2 bits can be allocated. At this time, since the allocation area for the entire submap is indicated in the SFCH, the MCS information can be known in the case of the last submap.

SFCH shall be able to receive all terminals of the cell. Therefore, the base station codes the SFCH with the lowest MCS and transmits it to all terminals in the cell. The lowest MCS in a particular cell may generally vary depending on the context of that cell. For example, in the case of a small cell in a room such as a femtocell, the reception performance of a terminal is superior to a general micro cell. Therefore, even if a base station transmits a coded message with a higher level of MCS than a microcell in a femtocell, all the terminals can receive the message.

The SFCH can be coded into a fixed MCS such as a commonly used Frame Control Header (FCH). Also, it can be coded with the changed MCS according to the channel environment or the cell environment. The base station can notify the terminal of the MCS information for the SFCH by using a preamble (or a synchronization channel) of a superframe header or a supermap (SuperMAP).

When the base station informs the UE of the MCS information of the SFCH using the super frame header, the MCS of the SFCH is kept the same during the superframe. When the UE acquires information on the MCS of the SFCH included in the superframe header, the UE can decode the SFCH using the information. The SFCH will have the lowest level of MCS level during the corresponding superframe.

The base station may transmit a super frame header (preferably a BCH) including the MCS information of the SFCH to the terminal. In addition, the superframe header may further include MCS set information used in a subframe. When the base station informs the UE of MCS set information for a subframe using a super frame header, the UE can decode the SFCH using the lowest MCS level included in the MCS set. Of course, when the base station selects and informs a specific value of the MCS level information included in the MCS set, the UE can decode the SFCH using the specific value.

Referring back to FIG. 16, the base station can transmit a submap header including submap type information and the number of submaps to the terminal (S1602).

Table 4 below shows an example of the submap header format used in another embodiment of the present invention.

Kinds Classification Item Number of bits

Submap header


Submap count information
Number of first type MAP X bit Second type MAP number X bit  ... X bit Nth type MAP number X bit The MCS of the next submap header 1 to 3 bits

Table 4 shows information included in the submap header transmitted to the terminal in step S1602. In one submap, a plurality of submap headers may exist depending on the MCS level used in the subframe.

The submap number information may include information on the type of the submap and information on the number of submaps according to the submap type. The 'MCS information of the next submap header' in Table 4 can perform the same function as the 'MCS information of the next submap header' in Table 3.

In step S1602, the submap header is used to reduce excessive blind decoding. That is, the base station informs the terminal of the type and number of submaps encoded with the same MCS. This allows the terminal to reduce excessive blind decoding.

The terminal can know the MCS information about the submap through the MCS information included in the submap header. The submap header may include information on the number of submaps of various types having different sizes. The number of bits in the submap header may vary depending on the type of submap type and the total number of submaps. In addition, the submap header may have various MCSs according to the reception environment of the MS. If the UL submap and the DL submap are separately located as in the mixed TDM / FDM scheme, the UL / DL map should be informed of a different type even if they are the same size.

Referring back to FIG. 16, the base station can transmit the submap body to the terminal following the submap header (S1603).

In step S1603, the submap body includes scheduling information on the downlink subframe. In addition, the submap body may further include scheduling information for the uplink subframe.

17 is a diagram showing an example of a submap structure used in another embodiment of the present invention.

17 shows the structure of a submap. In FIG. 17, the submap structure may include a Sub-Frame Control Header (SFCH), one or more SubMAP Headers, and one or more SubMAP bodies. Information included in the SFCH can be known with reference to Table 3, and information included in the submap header can be found by referring to Table 4.

Submaps can be classified into various types according to their sizes and Modulation and Coding Scheme (MCS) levels. The terminal can decode the submap if it knows the size of the submap and the MCS level.

FIG. 17 shows a case where submaps coded with MCSs of low code rate are sequentially arranged. There may be a plurality of dedicated submaps applied to a specific terminal, but the MCS level of each submodule is the same. For example, if a particular terminal uses a sub-map of a certain MCS level, the terminal can not decode the sub-mapped to another MCS level.

Referring to FIG. 17, an SFCH is allocated at the beginning of a submap. The SFCH is a channel for transmitting basic information on a subframe and is located at the beginning of each subframe. The SFCH may include various kinds of information, and may include information as shown in Table 3 as an example.

The base station can transmit a submap header including the type of the submap encoded with the same MCS and information on the number of submaps (Number of Type 1 SubMAP, ..., Number of Type N SubMAP) to the terminal. The UE can reduce excessive blind decoding using information included in the submap header. In addition, the submap header may include information on the MCS of the next submap header. At this time, the submap header may include the number of different types of submaps.

If there are two submaps of 30 bits or 40 bits before the encoding, the base station continuously transmits n submaps with 30 bits and m submaps with 40 bits. In IEEE 802.16m, one of the wireless access systems, it is assumed that there are a maximum of 10 to 16 submaps per subframe in a 10 MHz channel. At this time, approximately three to four bits are required to represent one type. Therefore, when there are two submap types, 6 bits (3 bits x 2 kinds) are required for the submap header. The number of bits for indicating the submap type may vary depending on the type of submap type and the total number of submaps. In another embodiment of the present invention, the submap header may have various MCS levels according to the reception environment of the terminal.

When the UL submap and the DL submap are separately located as in the mixed TDM / FDM scheme, the UL submap and the DL submap should be informed of different types even if they are allocated to the same size.

In FIG. 17, a submap (or a submap body) is a control channel for transmitting scheduling information for a control channel or a data channel allocated to the UE. The submap body may be encoded with various MCSs according to the reception environment of the terminal. A cyclic redundancy code (CRC) is appended to each submap body. At this time, the CRC uses a number (RNTI of 3GPP LTE, UE ID of HSDPA, CID of WiMAX) indicating a connection, such as PDCCH of 3GPP LTE system or HS-SCCH of HSDPA as an initial value. Accordingly, the UE can decode the CRC included in the submap and compare the decoded value with its own unique number to confirm whether the submap is correctly received or not. That is, the UE can confirm whether or not the received submap is a submap transmitted to the UE using the CRC. However, a broadcast message and the like have a unique number and can be recognized as a common control channel.

Table 5 below shows the types of DCI used in 3GPP LTE.

DCI Format Kinds Item 0 For UL-SCH Flag for format0 / format1A differentiation One Hopping flag One Resource block assignment 13 Transport format 5 New Data Indicator One TPC command for scheduled PUSCH 2 Cyclic shift for DM RS 3 CQI request One RNTI / CRC 16 One For DL SIMO channel Distributed transmission flag One Resource allocation header One Resource block assignment 25 MCS 5 HARQ process number 3 New Data Indicator One Redundancy Version 2 TPC command for PUCCH and persistent PUSCH 2 RNTI / CRC 16 1A For DL SIMO (Compact) Flag for format0 / format1A differentiation One Distributed transmission flag One Resource block assignment 13 Transport format 5 HARQ process number 3 Redundancy Version 2 TPC command for PUCCH and persistent PUSCH 2 RNTI / CRC 16 2 For DL MIMO Distributed transmission flag One Resource allocation header One Resource block assignment 25 TPC command for PUCCH and persistent 2 Number of layers 2 For the first codeword: Transport format 5 HARQ process number 3 New Data Indicator One Redundancy Version 2 For the second codeword: Transport format 5 HARQ swap flag One New Data Indicator One Redundancy Version 2 Precoding Information 4 Precoding Confirmation 14 RNTI / CRC 16 3 UL TPC (2 bit TPC) TPC command for user 1, user 2, ..., user N 3A UL TPC (1 bit TPC) TPC command for user 1, user 2, ..., user 2N

In FIG. 17, the types of the entire submaps can be configured as five types as shown in Table 10 below. At this time, the number of types defined in the submap header can be reduced by setting the size of the submap to be the same.

Table 6 below shows the types of submaps that can be used in another embodiment of the present invention.

DL multicast DL First DL Retran UL Grant UL TPC MAP Type 0 (separated by CID)
Multicast CID 1 to 2 (1) 0 to 1 (0) 0 (separated by CID) UL / DL (0 to 1) + 1st / Re (1) UL / DL (0 ~ 1)  Resource Assignment 9-13 11 to 14 (Mapping) +1 (Duration)) 2 to 4 RU Mapping (11)
Duration (0 ~ 2) Type Indicator (DL or UL: 0 to 1 bit), RU Mapping (11), Duration (0 to 2) Timer (2 to 4)
Persistent (?) MIMO Info 0 to 1 5 to 7 (5) 4 to 5 (4) 0 CDD or SFBC (1) or fixed MIMO Ind (0 ~ 1), Precoding Indi (2), CL_COL / OL (1), Rank (2), N_TxAnt CL / OL (0-1), Rank (1), PMI (3)  MCS 0 to 4 6 to 10 (6) 2 to 6 (2) 5 to 7 (6) 0 MCS (limited) Composite MCS (6-8) or Payload Size Index (6-8) + Mod (2) Modulation (2) Composite MCS (6-7) Payload Size Index (4-6)
Mod (1)  HARQ 0 to 2 6 to 9 (6) 7 to 12 (8) 6-11 (6) 0 Multicast HARQ ?? ND + Seq_No (1 to 3), N_Process (3)
Multiple CRC (1-2) Seq_No (2)
N_Process (3)
M CRC (1 to 2),
Mode (1 to 5) Seq_No (2),
N_Process (2)
Multiple CRC (1-2)
Mode (1 to 5)  TPC / TA 0 1 to 5 (1) 1 to 2 (1) TPC (1 ~ 2), DL Power Boosting (0 ~ 3) TPC (1-2)  CRC / CID 16 16 16  Total 24 to 35 (33) 46 to 63 (48) 43 to 62 (45) 43 ~ 56 (45) 3 to 6 (a total of 36 pieces are combined)

18 is a diagram illustrating a method of allocating a submap according to another embodiment of the present invention.

In another embodiment of the present invention, the base station can set the submap type in consideration of the MCS level of the submap and the size of the submap (S1801).

In step S1801, if the MBS level of the submap is 4 types and the size of the submap is 2 types, the total number of submap types is 8 (4 MCS x 2 type). When the type of the submap is set in advance, the base station may include MCS information, submap information, and the like in the SFCH to notify the terminal. Therefore, the base station does not have to transmit the submap header for each submap body. That is, the number of submap headers can be reduced.

The base station can allocate a submap and a control channel by transmitting an SFCH including information on a predetermined submap type and a size of a submap to the terminal (S1802).

Table 7 below shows an example of the format of the SFCH used in step S1902.

Kinds Classification Item Number of bits SFCH
(One per subframe) Subframe information Location information for distributed RUs X bits Subframe grouping information X bits Number of base station antennas [1-2] bits Submap information (size of area occupied by submap) X bits Broadcast message resource allocation X bits Number of submaps by type
(M = log ₂ (the maximum number of submaps that can be assigned to one type)) M * Number of types

Referring to Table 7, information on the subframes included in the SFCH can be known. In FIG. 18, it can be seen that there is one SFCH per subframe. The subframe information included in the SFCH may include location information of the distributed RU using the bitmap, grouping information of the subframe, and information on the number of Athena of the base station. Also, the SFCH includes information on the number of submaps according to the submap type (i.e., information on the size of the area occupied by the submap), message resource allocation information (i.e., resource allocation information on the broadcast message) .

In FIG. 18, the base station can set information on the submap type in advance. The terminal and the base station can share information on the submap type when performing the initial access procedure. Accordingly, the base station can allocate a submap to the terminal by transmitting information on the type of the submap and the number of submaps according to the submap type to the terminal using the SFCH to the terminal.

19 shows an example of a submap structure that can be used in another embodiment of the present invention.

FIG. 19 shows a submap structure in which a base station assigns to a terminal using the method of FIG. Referring to FIG. 19, a subframe control header (SFCH) may be located in a first OFDM symbol of a subframe. The SFCH of FIG. 19 may include the information described in Table 7. That is, the SFCH may include the number of submaps according to the submap type. The submap body can be classified according to the type of the submap.

20 is a diagram showing an example of subframe structures that can be used in embodiments of the present invention.

20 (a) shows a control channel structure when a submap is allocated by the TDM scheme. Referring to FIG. 20 (a), submaps are allocated by the TDM method. Also, the resource block (RU) may be composed of 5 OFDM symbols. At this time, a submap may be allocated in the OFDM symbol, and an ACK / NACK channel may be allocated to the remaining subchannel region as the SFCH and the control channel. However, the subchannel area remaining after allocating the SFCH and the control channel remains empty. In a submap-allocated symbol, an empty region can be used to measure the interference of other cells.

FIG. 20 (b) shows a subframe structure in the case of allocating a submap according to a variable TDM scheme. The allocation position of the submap may vary depending on the user's requirements or the channel environment. In FIG. 20 (b), the resource block RU may be composed of five or six OFDM symbols. 20 (b), the SFCH and the submap can be allocated to the TDM sub-channel region using n CAUs.

FIG. 20 (c) shows an example of a subframe structure in the case of allocating a submap according to a mixed TDM / FDM scheme. 20 (c), submaps are allocated in CAU units. The base station can allocate the SFCH and the DL submap to the OFDMA symbol fixedly in the TDM scheme and allocate the UL submap to the remaining area. In addition, the base station can leave the remaining subchannel area as an empty region. At this time, the empty area can be used to measure interference from other cells.

In FIG. 20 (c), the base station can allocate the UL submap from the top of the subchannel in the FDM scheme. At this time, the base station can allocate an ACK / NACK channel to an area allocated with the UL submap. After allocating UL subchannels, the base station can sequentially allocate data having the smallest MCS level.

20 (d) shows another example of the control channel structure in the case of allocating the subchannels by the mixed TDM / FDM scheme. The base station allocates the SFCH and DL submaps in a TDM manner. Also, the base station may allocate an ACK / NACK channel to the remaining region of the symbol. The base station can allocate the UL submap to the first RU of the subchannel in FDM fashion.

The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the above description should not be construed in a limiting sense in all respects and should be considered illustrative. The scope of the present invention should be determined by rational interpretation of the appended claims, and all changes within the scope of equivalents of the present invention are included in the scope of the present invention. In addition, claims that do not have an explicit citation in the claims may be combined to form an embodiment or included in a new claim by amendment after the application.

1 is a diagram showing a frame structure used in a broadband wireless access system (for example, IEEE 802.16).

2 shows an example of a subframe structure in a 3GPP LTE system.

Fig. 3 shows an example of a commonly used frame structure (a) and a frame structure (b) that can be used in the embodiments of the present invention.

4 is a diagram showing an example of a time division method (a) and a frequency division method (b) that can be used in the embodiments of the present invention.

5 is a diagram illustrating a method of allocating a subframe control header according to an embodiment of the present invention.

6 is a diagram showing an example of a subframe structure in a case where the TTI is in units of one subframe.

7 is a diagram showing an example of a subframe structure in a case where the TTI is 2 subframe units.

8 is a diagram illustrating a method of allocating a submap using an SFCH according to another embodiment of the present invention.

9 is a diagram illustrating a method of variably allocating a submap in a subframe according to an embodiment of the present invention.

10 is a diagram illustrating a method of assigning physical resources to logical channels that can be used in embodiments of the present invention.

11 is a diagram illustrating an example of a resource allocation method for a TDM control channel region in a subframe.

12 is a diagram showing an example of a cell-specific mapper used in FIG.

13 is a diagram illustrating a method of allocating submaps in a subframe to a mixed type of TDM / FDM according to another embodiment of the present invention.

FIG. 14 is a diagram illustrating a concrete method of allocating a submap in a subframe to a mixed type of TDM / FDM according to another embodiment of the present invention.

FIG. 15 is a diagram comparing wasteful resources of the TDM scheme, the FDM scheme, the variable TDM scheme, and the mixed TDM / FDM scheme.

16 is a diagram illustrating a method of allocating a submap according to another embodiment of the present invention.

17 is a diagram showing an example of a submap structure used in another embodiment of the present invention.

18 is a diagram illustrating a method of allocating a submap according to another embodiment of the present invention.

19 shows an example of a submap structure that can be used in another embodiment of the present invention.

20 is a diagram showing an example of subframe structures that can be used in embodiments of the present invention.

Claims (16)

A method for allocating a submap by a base station in a wireless access system, Allocating at least one resource region to a subframe according to the size of the submap; Allocating a control header, an uplink submap, and a downlink submap including the sub frame configuration information and the submap information to the at least one resource region in the at least one resource region; And And transmitting the control header, the uplink submap, and the downlink submap, Wherein the downlink submap is allocated in a time division multiplexing manner in the subframe and the uplink submap is allocated in a frequency division multiplexing manner in the subframe. The method according to claim 1, Wherein the at least one resource region comprises: And a control assignment unit including a predetermined resource unit, respectively. 3. The method of claim 2, Wherein each of the predetermined resource units included in the one or more resource areas comprises: And the sub-frames are distributed in a predetermined order in the entire frequency domain of the sub-frame. 3. The method of claim 2, Wherein the allocating the one or more resource areas comprises: Rearranging one or more control allocation units included in the one or more resource regions in a predetermined order on a predetermined symbol; And Further comprising the step of applying a permutation to a predetermined control allocation unit among the one or more control allocation units. 5. The method of claim 4, Wherein the rearranging comprises: Wherein the allocation order of the one or more control allocation units is changed using a predetermined rotation value. delete 3. The method of claim 2, Further comprising calculating a total resource requirement of the submap in units of symbols constituted by a predetermined subchannel, And allocating the control header and the submap when the total resource requirement of the submap is smaller than one symbol unit, And allocating the control header and the downlink submap to the first control allocation unit in a time division multiplexing manner. 8. The method of claim 7, Wherein the assigning of the control header and the submap comprises: Allocating the control header and the downlink submap to the first control allocation unit and allocating the uplink submap to the remaining subchannel area of the first control allocation unit. 9. The method of claim 8, And allocating the uplink submap using the second control allocation unit when the uplink submap is not allocated to the first control allocation unit. The method of claim 1, Further comprising calculating a total resource requirement of the submap in units of symbols constituted by a predetermined subchannel, And allocating the control header and the submap if the total resource requirement of the submap is greater than one symbol unit, Wherein the control header and the submap are allocated to a first symbol of the resource region, and the remaining submap allocated to the first symbol is allocated to a second symbol of the resource region. 11. The method of claim 10, Wherein the downlink submap is allocated first and the uplink submap is allocated to a remaining region. 3. The method of claim 2, Wherein the submap information includes information on the total number of the control allocation units to which the submap is allocated. The method according to claim 1, Wherein the submap includes at least one of information on a downlink control channel and information on an uplink control channel. The method according to claim 1, And transmitting the submap according to the submap information to the terminal. The method according to claim 1, Wherein the downlink submap is sequentially allocated from the first symbol in the time division multiplexing scheme and the uplink submap is sequentially allocated from the first subchannel in the frequency division multiplexing scheme. The method according to claim 1, Wherein the submap information includes first MCS information indicating a first MCS of the downlink submap and second MCS information indicating a second MCS of the uplink submap.

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