KR20100053837A - Apparatus and method for group resource allocation based on channel variation in a broadband wireless communication system - Google Patents

Abstract

PURPOSE: A group resource according allocating apparatus to channel variation in a broad band wireless communication system and a method thereof are provided to minimize overhead caused with group change by proceeding group classification through channel information and channel change rate information of a terminal and supporting a differentiated MCS(Modulation and Coding Scheme) level according to the group. CONSTITUTION: If a speed classification index of a terminal k exceeds a threshold value, BS(Base Station) decides allocation of group resources about the terminal k(203,205). A group supports all MCS(Modulation and Coding Scheme) levels. If the speed classification index is below the threshold value, the base station searches the group for a low speed terminal(207). The base station decides the allocation of the group resources of one group among the searched group about the terminal k(209).

Description

Apparatus and method for allocating group resource according to channel change in broadband wireless communication system

The present invention relates to a broadband wireless communication system, and more particularly, to an apparatus and method for allocating group resources according to channel change in a broadband wireless communication system.

In the next generation communication system, the first generation (hereinafter referred to as '4G') communication system, users are provided with services having various quality of service (QoS) using a transmission rate of about 100 Mbps. There is active research going on. The representative communication system is the Institute of Electrical and Electronics Engineers (IEEE) 802.16 system. The IEEE 802.16 system orthogonal frequency division multiplexing (hereinafter referred to as 'OFDM') / Orthogonal Frequency Division Multiple Access (orthogonal frequency division multiplexing) to support a broadband transmission network on a physical channel (Physical Channel) Multiple Access, hereinafter referred to as " OFDMA "

In a broadband wireless communication system such as the IEEE 802.16 system, a base station allocates resources to respective terminals for transmitting and receiving a packet. The base station transmits a map (MAP) message indicating a resource allocation result such as the location and size of the allocated resource, a modulation scheme, a coding rate, and the like through the downlink channel. In general, a message indicating a resource allocation result for uplink communication and a message indicating a resource allocation result for downlink communication are separately configured, and a unit of information required for one resource allocation is referred to as a map information element (IE). .

Resource allocation is performed on resources within a certain period. In this case, since resources for general data packets are allocated every predetermined period, a map IE for this is transmitted every predetermined period. The map IE is information that must be transmitted in order to convey a resource allocation result, but is an overhead of occupying resources competitively with the data packet. Therefore, a group resource allocation technique is used which groups resources having similar characteristics and delivers allocation information of the resources to one map IE. However, when the group resource allocation scheme is applied to packets having various codecs and various data rates such as Voice over Internet Protocol (VoIP) packets, overhead increases. In addition, since the group must be changed when the characteristics of the resource change, overhead caused by the group change occurs.

As described above, the number of map IEs is reduced through the group resource allocation scheme, but additional overhead occurs due to the characteristics of the group resource allocation scheme. Therefore, an alternative for maximizing the efficiency of the group resource allocation scheme by minimizing the overhead caused by various data rates and group changes should be presented.

Accordingly, an object of the present invention is to provide an apparatus and method for maximizing the efficiency of a group resource allocation scheme in a broadband wireless communication system.

It is still another object of the present invention to provide an apparatus and method for minimizing the overhead incurred when applying a group resource allocation scheme in a broadband wireless communication system.

Another object of the present invention is to provide an apparatus and method for differentiating a Modulation and Coding Scheme (MCS) level supported by a group in a broadband wireless communication system.

Another object of the present invention is to provide an apparatus and method for allocating resources using a resource allocation information code composed of a combination of an MCS level and a resource allocation size in a broadband wireless communication system.

According to a first aspect of the present invention for achieving the above object, an operation method of a base station in a broadband wireless communication system is based on at least one item of a speed classification index of a terminal and a modulation and coding scheme (MCS) level of the terminal. Determining a group to include the terminal, allocating a resource allocation information code corresponding to the MCS level of the terminal and the resource allocation size of the terminal according to the MCS type of the group, and the resource allocation information And a step of creating a group assignment information element (IE) including code, and transmitting a group assignment IE including the resource allocation information code.

According to a second aspect of the present invention for achieving the above object, an operation method of a terminal in a broadband wireless communication system, if a group resource is allocated through a group assignment IE, checking the MCS type of the group, and the MCS type And identifying a resource allocation information code assigned to the terminal according to the present invention, and identifying a location of the group resource allocated to the terminal using a resource unit offset (RU offset). do.

According to a third aspect of the present invention for achieving the above object, a base station apparatus in a broadband wireless communication system, based on at least one item of the speed classification index of the terminal and the MCS level of the terminal to the group to include the terminal; And an allocator for allocating a resource allocation information code corresponding to the MCS level of the terminal and the resource allocation size of the terminal according to the MCS type of the group, and a generator for creating a group allocation IE including the resource allocation information code. And a transmitter for transmitting a group allocation IE including the resource allocation information code.

According to a fourth aspect of the present invention for achieving the above object, in a broadband wireless communication system, if a terminal resource is allocated through a group assignment IE, the terminal device checks the group's MCS type and the terminal according to the MCS type. And a manager for identifying a resource allocation information code assigned to the terminal and a manager for identifying the location of the group resource allocated to the terminal using a resource unit offset.

In a broadband wireless communication system, grouping is performed by using channel information and channel change rate information of a terminal, and by supporting differentiation of Modulation and Coding Scheme (MCS) level according to groups, group resources are minimized with only minimum overhead. And minimize the overhead of group changes.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Hereinafter, a description will be given of a technique for maximizing the efficiency of a group resource allocation scheme in a broadband wireless communication system. Hereinafter, the present invention will be described using an Orthogonal Frequency Division Multiplexing (OFDM) / Orthogonal Frequency Division Multiple Access (OFDMA) scheme as an example. The same applies to other wireless communication systems.

The frame structure of the broadband wireless communication system according to the present invention is shown in FIG.

As illustrated in FIG. 1, one superframe 110 is configured of a plurality of frames 120. Each frame 120 is composed of a plurality of subframes 130, and each subframe 130 is composed of a plurality of OFDMA symbols. Resource allocation is performed for resources in each subframe 130, and resources in each subframe 130 are allocated in units of a resource unit (RU) 140. That is, the terminal communicating with the base station is assigned an integer number of resource units.

Therefore, the map message is transmitted for each subframe 130. At this time, each of the map IEs indicating the resource allocation result included in the map message is subjected to a cyclic redundancy check (CRC) using a unique sequence allocated to the terminal that needs to receive the map IE. Therefore, each terminal distinguishes the map IE for itself by CRC checking each of the map IEs in a unique sequence assigned to it. This map IE encoding scheme is called separate coding.

In order to apply the group resource allocation scheme, a process of grouping terminals having similar resource allocation information into one group is required. Here, the resource allocation information includes a Modulation and Coding Scheme (MCS) level, a resource allocation size and a resource allocation position. At this time, since the MCS level and the resource allocation size as information that can be common between different terminals, a grouping process is performed based on the MCS level and the resource allocation size.

Different resource allocation sizes are required according to the type of service, and even the same service may change its resource allocation size due to a change in data rate according to channel conditions. The MCS level may change according to the position of the terminal in the cell, that is, the channel quality. That is, the MCS level is determined according to the location of the terminal in the cell, and the resource allocation size is determined according to the type of service and data rate. For example, when the terminal is moving, the channel condition changes with time, so the MCS level changes with time.

As a specific example, in the case of a Voice over Internet Protocol (VoIP) service, after a call is established, the user is in a talking state, that is, an 'ACTIVE STATE' in which a transmission packet occurs and a non-speaking state, that is, a transmission packet does not occur. 'INACTIVE STATE' exists. In the 'ACTIVE STATE' section, voice data is transmitted through a VoIP packet, and a SID (System IDeitification) packet is transmitted to indicate that the inactive state is transmitted in the 'INACTIVE STATE' section.

Codecs commonly used for the VoIP service include Enhanced Variable Rate Codec (EVRC), Adaptive Multi-Rate (AMR), GSM6.10, G.711, G.732.1, G.729A, and the like. The VoIP codecs listed above have different transmission periods and data rates. The VoIP packet includes voice data determined by the data rate of the VoIP codec, a media header (MAC) header, a cyclic redundancy check (CRC), and a protocol header. For example, in the case of the AMR, the 6-byte MAC header, the 2-byte CRC, the 3-byte protocol header, the 33-byte 'ACTIVE STATE' voice data, and the 7-byte 'INACTIVE STATE' silence information. Configures the VoIP packet. Therefore, in the case of the AMR, 44 bytes of AMR VoIP packets are transmitted in the 'ACTIVE STATE' section, and 18 bytes of SID packets are transmitted in the 'INACTIVE STATE' section. For other VoIP codecs, most VoIP packets are 18 to 44 bytes in size.

Allocates resources in units of a resource unit (RU) consisting of 18 subcarriers and 6 symbols, and some tones in one resource unit are used for pilot, resulting in a total of 96 tones Assuming a system used for packet transmission, the resource allocation size required to transmit a VoIP packet having a size of 18 to 44 bytes according to the MCS level is shown in Table 1 below. In Table 1, the unit of resource allocation size is a resource unit.

QPSK 1/2 QPSK 3/4 16-QAM 1/2 16-QAM 3/4 64-QAM 2/3 64-QAM 3/4 64-QAM 5/6 44 4 3 2 2 One One One 43 4 3 2 2 One One One 42 4 3 2 2 One One One 41 4 3 2 2 One One One 40 4 3 2 2 One One One 39 4 3 2 2 One One One 38 4 3 2 2 One One One 37 4 3 2 2 One One One 36 3 2 2 One One One One 35 3 2 2 One One One One 34 3 2 2 One One One One 33 3 2 2 One One One One 32 3 2 2 One One One One 31 3 2 2 One One One One 30 3 2 2 One One One One 29 3 2 2 One One One One 28 3 2 2 One One One One 27 3 2 2 One One One One 26 3 2 2 One One One One 25 3 2 2 One One One One 24 2 2 One One One One One 23 2 2 One One One One One 22 2 2 One One One One One 21 2 2 One One One One One 20 2 2 One One One One One 19 2 2 One One One One One 18 2 One One One One One One

As shown in Table 1, in order to represent resource allocation information for VoIP packets according to MCS level and packet size, Quadratue Phase Shift Keying (QPSK) 1/2, QPSK 3/4, and 16-QAM (Quadrature Amplitude) Modulation) Seven MCS levels, such as 1/2, 16-QAM 3/4, 64-QAM 2/3, 64-QAM 3/4, 64-QAM 5/6, must be distinguished and 1 to 8 resource units Resource allocation sizes should be distinguished. That is, since 3 bits are required for MCS level classification and 2 bits are required for resource allocation size classification, the total resource allocation information is 5 bits.

When allocating group resources, using 5 bits of resource allocation information per terminal generates a lot of overhead. Since the VoIP service must support various codecs and various data rates, the resource allocation size to be supported for VoIP packet transmission differs according to the MCS level. However, the type of resource allocation size that should be supported according to each MCS level is not as large as that of VoIP packet size. Therefore, in order to reduce overhead, it is more effective to use 'resource allocation information code' combining MCS level and resource allocation size rather than allocating MCS level and resource allocation size. When transmitting the VoIP packets of 18 to 44 bytes at various MCS levels as shown in Table 1, resource allocation information is represented by only 13 combinations as shown in Table 2 below.

Serial Number MCS level and resource allocation size combination One QPSK 1/2 with 4RUs 2 QPSK 1/2 with 3RUs 3 QPSK 1/2 with 2RUs 4 QPSK 3/4 with 3RUs 5 QPSK 3/4 with 2RUs 6 QPSK 3/4 with 1RU 7 16-QAM 1/2 with 2RUs 8 16-QAM 1/2 with 1RU 9 16-QAM 3/4 with 2RUs 10 16-QAM 3/4 with 1RU 11 16-QAM 2/3 with 1RU 12 16-QAM 3/4 with 1RU 13 16-QAM 5/6 with 1RU

Four bits of information are required to indicate the 13 combinations shown in Table 2. Since all MCS levels are represented when group resource allocation is performed using a 4-bit resource allocation information code representing the 13 combinations, even if the MCS level of the terminals in the group is changed, the changed MCS level and resource allocation in one group are changed. The size can all be indicated through four bits of information.

When the 4-bit resource allocation information code is used, the change of allocation information can be indicated without changing the group. However, the resource allocation information of the group, that is, the group allocation IE, is QPSK 1 /, which is the lowest MCS level among the 13 combinations. It should be coded and modulated in accordance with 2. In other words, the size of the map increases. Therefore, in order to reduce the overhead of the map, it is necessary to adjust the MCS level of the group resource allocation information by differentiating the MCS levels according to the groups. In case of limiting the MCS level supported in the group according to the differentiation of the MCS levels, a resource allocation information code having a size less than 4 bits can be configured. In other words, when the groups are formed by differentiating the supported MCS levels, the size of the group allocation IE is reduced because the MCS level of the group resource allocation information is determined according to the MCS levels supported by each group. The overhead required for is also reduced. However, when the MCS level supported by the group is limited, a case in which the group change is required when the MCS level changes according to the channel change of the UE belonging to the group may occur. That is, when changing to an unsupported MCS level in a group, procedural overhead of changing a group to a new group occurs.

When the resource allocation information code is expressed in many bits, the overhead of group resource allocation information and the transmission overhead of the group allocation IE increase, but the group change overhead is reduced because the type of MCS level supported increases. On the other hand, when the resource allocation information code is represented with a small number of bits, the overhead of group resource allocation information and the group allocation IE are reduced, but the group change overhead is increased because the type of MCS level to be supported is reduced. Therefore, in order to minimize the overhead of the group resource allocation information, the group allocation IE, and the group change overhead, the length of the resource allocation information code is not uniform, and a structure that varies according to a group is preferable.

The group using the resource allocation information code composed of few bits is suitable for low speed terminals with low frequency of MCS change because the MCS level supported is relatively small, and the group using the resource allocation information code composed of many bits has the supported MCS level. Since it is relatively large, it is suitable for high speed terminals with high frequency of MCS change. That is, the length of the resource allocation information code is affected by the moving speed of the terminal, that is, the channel change rate. The faster the movement speed of the terminal, the higher the rate of change of the MCS, and the slower the movement speed of the terminal, the lower the rate of change of the MCS. Here, the change of the MCS level of the terminal can be easily identified using the channel information coming from the terminal. Therefore, the group to which the terminals with low mobile speeds can reduce the length of the resource allocation information code by reducing the number of MCS levels supported. At this time, in order to support various VoIP codecs and various VoIP data rates, a lower MCS level should support more resource allocation size. As a result, the larger the number of MCS levels in the group and the lower the MCS level supported by the group, the longer the resource allocation information code. The smaller the number of MCS levels supported by the group and the higher the MCS level, the higher the resource allocation information code. Reduces the length of

In other words, in order to support various VoIP codecs and data rates and to reduce the overhead due to group resource allocation, it is necessary to configure groups and determine the resource allocation information code length in consideration of the moving speed and the MCS level of the terminal. . When configuring a group, it is necessary to classify the high speed terminal and the low speed terminal, and classify the group according to the MCS level of the low speed terminals. In this case, groups configured according to the moving speed and the MCS level of the terminal are classified into 'MCS type', and different resource allocation information code sets are applied according to the MCS type. The UE can know the type of MCS level supported by the group to which the UE belongs through the MCS type, and can also know the length of the resource allocation information code. At this time, by applying the resource allocation information code set corresponding to the MCS type, the overhead for informing the length of the resource allocation information code used for each MCS type is eliminated.

As described above, by expressing the MCS level and the resource allocation size in the resource allocation information code, the amount of information required for resource allocation can be reduced. In addition, by classifying the MCS type according to the type of MCS level supported, and assigning the resource allocation information code set having different information and different length for each MCS type, the resource allocation information code is used in all groups with the same length. Compared to the scheme, the amount of information required for resource allocation is reduced. In addition, the group change information may be reduced by including the MCS type group having many MCS levels that support the high speed terminal by using the moving speed. And, by including the low speed terminal in the group of MCS type of limited MCS level type, the low speed terminal uses a resource allocation information code of a relatively short length, thereby reducing the amount of information required for resource allocation, Moreover, due to the differentiation of the MCS level, the size of the group assignment IE can be reduced by increasing the transmission MCS level of the group assignment IE.

An example of group allocation IE using the MCS type and resource allocation information code considering the moving speed of the terminal and the MCS level of the terminal is shown in Table 3 below.

Syntex Size (bit) Notes GRA_Assignment_IE {  Type 4  GROUP ID 4  MCS TYPE 2 00: MCS GROUP # 1
01: MCS GROUP # 2
10: MCS GROUP # 3
11: MCS GROUP # 4  RU offse 6 Start position of resource for use by group resources  USER BITMAP variable Specify terminals to which resources are allocated through group resource allocation and terminals not to be allocated resources  RESOURCE BITMAP 'Resource Allocation Information Code' information for terminals specified to be allocated resources through USER BITMAP  CRC 16 }

As shown in Table 3, since the group assignment IE is transmitted in the form of a map, the group assignment IE includes a 'Type' field to indicate the type. The group assignment IE includes a 'GROUP ID' field for identifying each group and a 'MCS TYPE' field indicating an MCS level supported by the group. In addition, since resources of the same group are continuously allocated to each other, the group allocation IE includes a 'RU Offset' field indicating a start position of group resources, and includes a terminal to which group resources are allocated among terminals belonging to a group. Contains the 'USER BITMAP' field to specify. The terminal corresponding to the position of the bit set to '1' among the bitmaps set in the 'USER BITMAP' field is a terminal to which a group resource is allocated, and the terminal corresponding to the position of the bit set to '0' is not allocated a group resource. Not the terminal. The 'RESOURCE BITMAP' field is a bitmap indicating a resource allocation information code. That is, a bitmap connecting resource allocation information codes for terminals corresponding to positions of bits set to '1' in 'USER BITMAP' is set in the 'RESOURCE BITMAP' field. In addition, a 'CRC' field for the group assignment IE is included. In this case, the value of the 'CRC' field is set to a common CRC code known to all terminals that should receive the group assignment IE.

For example, the MCS level supported for each MCS TYPE may be configured as shown in Table 4 below.

Type MCS level MCS GROUP # 1 QPSK1 / 2, QPSK3 / 4, 16-QAM1 / 2 MCS GROUP # 2 QPSK3 / 4, 16-QAM1 / 2, 16-QAM3 / 4, 64-QAM2 / 3 MCS GROUP # 3 16-QAM1 / 2, 16-QAM3 / 4, 64-QAM2 / 3 MCS GROUP # 4 QPSK1 / 2, QPSK3 / 4, 16-QAM1 / 2, 16-QAM3 / 4, 64-QAM2 / 3

In Table 4, MCS GROUP # 1, MCS GROUP # 2 and MCS GROUP # 3 are groups formed as a result of differentiating the MCS level that can be supported for a terminal having a low speed, and MCS GROUP # 4 is a high speed A group that provides all MCS levels for a terminal having a. Here, the resource allocation information code for each group may be configured as shown in Table 5 below.

MCS GROUP number MCS TYPE index Code MCS level & RU


#One




00



000 QPSK 1/2 with 4RUs 001 QPSK 1/2 with 3RUs 010 QPSK 1/2 with 2RUs 011 QPSK 3/4 with 3RUs 100 QPSK 3/4 with 2RUs 101 QPSK 3/4 with 1RU 110 16-QAM 1/2 with 2RUs 111 16-QAM 1/2 with 1RU


#2





01



000 QPSK 3/4 with 3RUs 001 QPSK 3/4 with 2RUs 010 QPSK 3/4 with 1RU 011 16-QAM 1/2 with 2RUs 100 16-QAM 1/2 with 1RU 101 16-QAM 3/4 with 2RUs 110 16-QAM 3/4 with 1RU 111 64-QAM 2/3 with 1RU
# 3


10

00 16-QAM 1/2 with 2RUs 01 16-QAM 1/2 with 1RU 10 16-QAM 3/4 with 1RU 11 64-QAM 2/3 with 1RU







#4













11





0000 QPSK 1/2 with 4RUs 0001 QPSK 1/2 with 3RUs 0010 QPSK 1/2 with 2RUs 0011 QPSK 3/4 with 3RUs 0100 QPSK 3/4 with 2RUs 0101 QPSK 3/4 with 1RU 0110 16-QAM 1/2 with 2RUs 0111 16-QAM 1/2 with 1RU 1000 16-QAM 3/4 with 2RUs 1001 16-QAM 3/4 with 1RU 1010 64-QAM 2/3 with 1RU 1011 64-QAM 3/4 with 1RU 1100 64-QAM 5/6 with 1RU 1101 reserved 1110 reserved 1111 reserved

As shown in Table 5, a group having an MCS TYPE of 00 or 01 uses a 3-bit resource allocation information code, a group having an MCS TYPE of 10 uses a 2-bit resource allocation information code, and an MCS TYPE. This group of 11 uses a 4-bit resource allocation information code. That is, by applying different size of resource allocation information codes according to MCS TYPE, the amount of information required for resource allocation is greatly reduced compared to the case where the length of resource allocation information codes is fixed to one.

Hereinafter, the operation and configuration of a base station and a terminal using a group resource as described above will be described in detail with reference to the accompanying drawings.

2 is a flowchart illustrating an operation procedure of a base station in a broadband wireless communication system according to an exemplary embodiment of the present invention. FIG. 2 illustrates a procedure of group classification and group resource allocation for one terminal for convenience of description. However, since one group includes a plurality of terminals, it is obvious that the base station repeatedly performs the procedure shown in FIG. 2 with respect to the terminals to which group resources are allocated.

Referring to FIG. 2, the base station measures the speed classification index of the terminal k in step 201. That is, the base station measures an index indicating the speed in order to determine whether the terminal k is a high speed terminal or a low speed terminal. For example, the base station uses a movement speed of the terminal k directly measured using a global positioning system (GPS), uses movement speed information fed back from the terminal k, or a reference signal transmitted and received between the base station and the terminal. The speed classification index is measured using a moving speed estimated by using a reference signal or by using a channel change rate.

After measuring the speed classification index of the terminal k, the base station proceeds to step 203 and checks whether the speed classification index of the terminal k exceeds a threshold. Here, the speed classification index is a value having a higher value as the moving speed is faster.

If the rate classification index exceeds the threshold, the base station proceeds to step 205 and determines to allocate a group resource of the group k that supports all MCS levels to the terminal k. That is, the base station includes the terminal k in a group for a high speed terminal supporting all MCS levels, regardless of the current MCS level of the terminal k. For example, when the supportable MCS level for each MCS type is as shown in Table 5, the base station determines to allocate a group resource of the group whose MCS type is '11' to the terminal k.

On the other hand, if the speed classification index is less than or equal to the threshold, the base station proceeds to step 207 to search for a group for a low speed terminal supporting the MCS level of the terminal k. That is, the base station searches for a group that supports the MCS level of the terminal k except for a group that supports all MCS levels among the groups currently generated. For example, when the supportable MCS level for each MCS type is as shown in Table 5 and the MCS level of the terminal k is QPSK 3/4, at least one MCS type is '00' and at least one MCS. Groups of type '01' are retrieved.

In step 209, the base station determines to allocate the group resource of the group having the highest lowest MCS level among the at least one searched group to the terminal k. That is, since the group assignment IE is encoded and modulated to the lowest MCS level among the supported MCS levels, the base station selects the group k having the lowest MCS level of the terminal k in order to minimize transmission overhead. Include it in For example, the MCS level supported by each MCS type is shown in Table 5, the MCS level of the terminal k is QPSK 3/4, and the group A having the MCS type '00' and the MCS type '00'. When Group B and Group C having an MCS type of '01' are found, the base station determines to allocate group resources of Group C to the terminal k.

In step 211, the base station allocates a group resource of the corresponding group to the terminal k, and allocates a resource allocation information code according to the MCS type. In other words, the base station determines the amount of resources to be allocated to the terminal k, and allocates a resource allocation information code corresponding to the MCS level of the terminal k and the resource allocation size of the terminal k of the resource allocation information codes according to the MCS type do.

In step 213, the base station creates a group assignment IE. That is, the base station creates a user bitmap and a resource bitmap of the group to which the terminal k belongs, and then 'IE TYPE' field, 'GROUP ID' field, 'MCS TYPE' field, 'RU offset' field, 'USER BITMAP' Create a group assignment IE that contains a 'field, a' RESOURCE BITMAP 'field, and a' CRC 'field. Here, the base station sets a bit of a position corresponding to at least one terminal including the terminal k to which a group resource is allocated among the terminals belonging to the group in the user bitmap to '1'. The base station creates the resource bitmap by connecting resource allocation information codes allocated to at least one terminal including the terminal k to which the group resource is allocated. In this case, when the terminal k is newly included in the group, the base station additionally includes a field in the group allocation IE to inform the terminal k of the index of the bit corresponding to the terminal k in the user bitmap. Create a separate IE for notifying the terminal k of the group ID of the group.

After creating the group assignment IE, the base station proceeds to step 215 and transmits the group assignment IE and group packets. In detail, the base station performs CRC processing on the group allocation IE with a group allocation CRC code, and then encodes and modulates the group allocation IE according to the lowest MCS level of the group. In addition, the base station encodes and modulates the group packets according to the MCS level of each terminal. Subsequently, the base station converts complex symbols of the group assignment IE and complex symbols of the group packets into OFDM symbols by performing an inverse fast fourier transform (IFFT) operation and cyclic prefix (CP) insertion. Up-conversion to an RF (Radio Frequency) band signal and transmitting through an antenna.

3 is a flowchart illustrating an operation procedure of a terminal in a broadband wireless communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 3, the terminal searches for a group assignment IE including a group ID assigned to the terminal among the group assignment IEs received in step 301. That is, the terminal down-converts the RF band signal received through the antenna to a baseband signal, divides the baseband signal into OFDM symbol units, and removes the frequency band signal through CP elimination and fast fourier transform (FFT) operation. And restore the map IEs by converting the signals mapped to the location of the map message into a bit string. Then, the terminal CRC checks the map IEs using a group assignment CRC code, determines that map IEs that are successful in CRC checking are group assignment IEs, and then searches a group assignment IE of the group among the group assignment IEs.

After searching for the group assignment IE of the own group, the terminal proceeds to step 303 and checks whether the bit of the position corresponding to the user in the user bitmap is set to '1'. In other words, the terminal checks whether group resources are allocated to the terminal. If the bit of the position corresponding to the self is set to '0', the terminal terminates this procedure without performing communication through the group resource.

On the other hand, if the bit of the position corresponding to the self is set to '1', the terminal proceeds to step 305 to check the MCS type of the group. That is, the terminal checks the MCS type of the group through the 'MCS TYPE' field of the group assignment IE.

After checking the MCS type of the group, the terminal proceeds to step 307 to check the resource allocation information code assigned to itself according to the identified MCS type. In other words, the terminal divides the resource bitmap included in the group allocation IE into resource allocation information codes according to the MCS type, and then selects a bit of a position corresponding to one of the bits set to 1 in the user bitmap. Check the resource allocation information code corresponding to the rank of For this reason, the terminal determines the MCS level and resource allocation size allocated to the terminal.

After checking the resource allocation information code, the terminal proceeds to step 309 to check the starting position of the group resource of the group through the resource unit offset included in the group allocation IE, and using the starting position for itself Check the location of the resource. That is, since the group resources are continuously arranged, the terminal checks the position of the resource for itself by summing the resource allocation size sum of the resources for the terminal having a higher priority than the starting position.

Thereafter, the terminal proceeds to step 311 to perform communication through the group resources allocated to the terminal. That is, the terminal extracts a signal received through the group resource allocated to the terminal, and then restores the data packet by demodulating and decoding according to the assigned MCS level.

4 is a block diagram of a base station in a broadband wireless communication system according to an exemplary embodiment of the present invention.

As shown in FIG. 4, the base station includes a speed indicator 402, a resource allocator 404, a map generator 406, a map encoder 408, a data buffer 410, and a data encoder. (data encoder) 412, symbol modulator 414, subcarrier mapper 416, OFDM modulator 418, RF transmitter 420.

The speed indicator measuring instrument 402 measures the speed classification index of the terminal. That is, the speed indicator measuring instrument 402 measures an index indicating a speed for determining whether the terminal is a high speed terminal or a low speed terminal. For example, the speed indicator measuring instrument 402 uses the movement speed of the terminal k directly measured using GPS, uses the movement speed information fed back from the terminal, or receives a reference signal transmitted and received between the base station and the terminal. The speed classification index is measured by using the estimated moving speed or by using a channel change rate.

The resource allocator 404 allocates resources to terminals accessing the base station. In this case, the resource allocator 404 performs resource allocation for each subframe. That is, the resource allocator 404 allocates resources according to at least one of a group allocation scheme and a general allocation scheme. In particular, according to the group allocation method, the resource allocator 404 determines a group to include the terminal according to the resource characteristics of the terminal. In detail, for example, any terminal k, the resource allocator 404 checks whether the speed classification index of the target terminal k exceeds a threshold. If the rate classification index exceeds the threshold, the resource allocator 404 determines to allocate a group resource of the group k that supports all MCS levels. For example, when the supportable MCS level for each MCS type is as shown in Table 5, the base station determines to allocate a group resource of the group whose MCS type is '11' to the terminal k. On the other hand, if the speed classification indicator is less than or equal to the threshold, the resource allocator 404 may allocate the group resource of the group having the lowest lowest MCS level among the groups for the low speed terminal supporting the MCS level of the terminal. Determine what to assign to k. For example, the MCS level supported by each MCS type is shown in Table 5, the MCS level of the terminal k is QPSK 3/4, and the group A having the MCS type '00' and the MCS type '00'. When group B and group C having MCS type '01' are found, the resource allocator 404 determines to allocate group resources of group C to the terminal k. The resource allocator 404 allocates the group resource of the corresponding group to the terminal k, and allocates a resource allocation information code according to the MCS type. In other words, the resource allocator 404 determines the amount of resources to be allocated to the terminal k, and corresponds to the MCS level of the terminal k and the resource allocation size of the terminal k among the resource allocation information codes according to the MCS type. Assign resource allocation information code.

The map generator 406 generates a map message for notifying the resource allocation result of the resource allocator 404. The map message may include at least one of a map IE and a group assignment IE, and may include a plurality of map IEs or a plurality of group assignment IEs. At this time, the map IE and the group assignment IE are in accordance with a pre-determined IE configuration. For example, the group assignment IE is configured as shown in Table 3. That is, the map generator 406 creates a user bitmap and a resource bitmap of the group to which the terminal k belongs, and then 'IE TYPE' field, 'GROUP ID' field, 'MCS TYPE' field, 'RU offset' field. Create a group assignment IE that contains a 'USER BITMAP' field, a 'RESOURCE BITMAP' field, and a 'CRC' field. Here, the map generator 406 sets a bit of a position corresponding to at least one terminal including the terminal k to which group resources are allocated among the terminals belonging to the group to '1'. The map generator 406 creates the resource bitmap by connecting resource allocation information codes allocated to at least one terminal including the terminal k to which the group resource is allocated. In this case, when the terminal k is newly included in the group, the map generator 406 adds a field for notifying the terminal k of the index corresponding to the terminal k in the user bitmap to the group assignment IE. Include a separate IE for informing the terminal k of the group ID of the group.

The map encoder 408 CRC processes the map IE and the group assignment IE with a corresponding CRC code. That is, the map encoder 408 CRC processes the map IE into a unique sequence of a terminal that is a destination of the map IE, and CRC processes the group assignment IE into a group assignment CRC code. Accordingly, the map IE can be decoded only by the destination terminal of the map IE, and the group assignment IE can be decoded by terminals that know the group assignment CRC code.

The data buffer 410 stores data to be transmitted to the terminals, and provides the stored data to the data encoder 412 according to the resource allocation result of the resource allocator 404. The data encoder 412 performs channel coding on the data bit stream provided from the data buffer 410. The symbol modulator 414 demodulates the channel-coded bit string and converts the complex code into complex symbols. The subcarrier mapper 416 maps the complex symbols to the frequency domain according to the resource allocation result of the resource allocator 404. The OFDM modulator 418 configures OFDM symbols by converting complex symbols mapped to the frequency domain into a time domain signal through an IFFT operation, and inserting a CP. The RF transmitter 420 up-converts the baseband signal into an RF band signal and transmits it through an antenna.

5 is a block diagram of a terminal in a broadband wireless communication system according to an exemplary embodiment of the present invention.

As shown in FIG. 5, the terminal includes an RF receiver 502, an OFDM demodulator 504, a subcarrier mapper 506, a symbol demodulator 508, a data decoder 510, and a map decoder ( a map decoder 512, a map interpreter 514, and a resource status manager 516.

The RF receiver 502 downconverts an RF band signal received through an antenna to a baseband signal. The OFDM demodulator 504 divides the signal provided from the RF receiver 502 in OFDM symbol units, removes CP, and restores complex symbols mapped to the frequency domain through an FFT operation. The subcarrier demapper 506 extracts a signal mapped to a resource allocated to the terminal among complex symbols mapped to a frequency domain. The symbol demodulator 508 converts the complex symbols into a bit string by demodulating the complex symbols. The symbol demodulator 508 provides an encoded bit string of data to the data decoder 510 and a bit string of a map message to the map decoder 512. The data decoder 510 restores the data bit stream by channel decoding the bit stream provided from the symbol demodulator 508.

The map decoder 512 divides the bit string of the map message in units of IEs, and classifies a map IE for the terminal and a group allocation IE indicating a resource change among the IEs. In other words, the map decoder 512 CRC checks each of the IEs in a unique sequence of the terminal, and determines that the IE does not generate an error as a map IE for the terminal. The map decoder performs a CRC check on each of the IEs using the group allocation CRC code, and determines that the IE does not generate an error as a group allocation IE as a result of the CRC check.

The map interpreter 514 checks the resource allocation information included in the map IE for the terminal identified by the map decoder 512 and the group resource allocation information included in the group allocation IE. In other words, the map interpreter 514 checks the newly allocated resources through the map IE according to the previously promised IE format, and checks the group resource allocation information through the group allocation IE. For example, the group assignment IE is configured as shown in Table 3. That is, the map interpreter 514 checks whether the bit of the position corresponding to the terminal is set to '1' in the user bitmap included in the group assignment IE. If the bit of the position corresponding to the terminal is set to '1', the map interpreter 514 checks the MCS type of the group. That is, the map interpreter 514 checks the MCS type of the group through the 'MCS TYPE' field of the group assignment IE. The map interpreter 514 checks the resource allocation information code assigned to the terminal according to the identified MCS type. In other words, the map interpreter 514 divides the resource bitmap included in the group allocation IE into resource allocation information codes according to the MCS type, and then among the bits set to '1' in the user bitmap. Check the resource allocation information code corresponding to the rank of the bit at the position corresponding to. Accordingly, the map interpreter 514 grasps the MCS level and resource allocation size allocated to the terminal, and provides the MCS level and the resource allocation size information to the resource status manager 516. In addition, the map interpreter 514 checks the start position of the group resource of the group through the resource unit offset included in the group assignment IE and provides the start position information to the resource status manager 516.

The resource status manager 516 manages the status of resources allocated to the terminal according to the resource allocation information confirmed by the map interpreter 514. The resource status manager 516 controls the subcarrier mapper 506 to extract a signal received through the resource allocated to the terminal. In particular, when a group allocation IE is received, the resource status manager 516 is allocated to the terminal according to the start position, the MCS level, and the resource allocation size information of the group resource provided from the map interpreter 916. Check the location of the resource. That is, since the group resources are continuously arranged, the resource status manager 516 checks the location of the resource for itself by summing the resource allocation size sum of the resources for the terminals having a higher priority than the terminal to the starting position. .

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

1 is a diagram illustrating an example of a frame structure in a broadband wireless communication system according to the present invention;

2 is a diagram illustrating an operation procedure of a base station in a broadband wireless communication system according to an embodiment of the present invention;

3 is a view illustrating an operation procedure of a terminal in a broadband wireless communication system according to an embodiment of the present invention;

4 is a block diagram of a base station in a broadband wireless communication system according to an embodiment of the present invention;

5 is a block diagram of a terminal in a broadband wireless communication system according to an exemplary embodiment of the present invention.

Claims (22)

A method of operating a base station in a broadband wireless communication system, Determining a group to include the terminal based on at least one item of a speed classification index of the terminal and a modulation and coding scheme (MCS) level of the terminal; Allocating a resource allocation information code corresponding to the MCS level of the terminal and the resource allocation size of the terminal according to the MCS type of the group; Creating a group allocation IE (Information Element) including the resource allocation information code; And transmitting a group allocation IE including the resource allocation information code. The method of claim 1, The group allocation IE may include a 'GROUP ID' field for identifying a group, an MCS type indicating a type of MCS level supported by a group, a resource unit offset (RU Offset: Resource Unit offset) indicating a start position of group resources, And at least one of a user bitmap for specifying a terminal to which a group resource is allocated among the terminals belonging to the group, and a resource bitmap indicating a resource allocation information code. The method of claim 2, The process of creating the group assignment IE, Setting a bit of a position corresponding to at least one terminal to which the group resource is allocated in the user bitmap to '1'; And generating the resource bitmap by linking resource allocation information codes allocated to at least one terminal to which the group resource is allocated. The method of claim 3, And including a field in the group assignment IE to inform the terminal of an index of a bit corresponding to the terminal in the user bitmap. The method of claim 1, The process of transmitting the group assignment IE, CRC processing the group assignment IE with a group assignment cyclic redundancy check (CRC) code; And encoding and modulating the group allocation IE according to the lowest MCS level of the group. The method of claim 1, Determining a group to include the terminal, Determining that the terminal is included in a group supporting all MCS levels when the speed classification index of the terminal exceeds a threshold; If the speed classification index of the terminal is less than or equal to a threshold, determining that the terminal is included in the group having the lowest lowest MCS level among at least one group supporting the MCS level of the terminal. Way. In the method of operating a terminal in a broadband wireless communication system, When the group resource is allocated through the group assignment IE (Information Element), the process of checking the MCS (Modulation and Coding Scheme) type of the group, Checking a resource allocation information code assigned to the terminal according to the MCS type; And identifying a location of the group resource allocated to the terminal using a resource unit offset (RU offset). The method of claim 7, wherein The group allocation IE may include a 'GROUP ID' field for identifying a group, an MCS type indicating a type of MCS level supported by a group, a resource unit offset (RU Offset: Resource Unit offset) indicating a start position of group resources, And at least one of a user bitmap for specifying a terminal to which a group resource is allocated among the terminals belonging to the group, and a resource bitmap indicating a resource allocation information code. The method of claim 8, And determining whether a group resource is allocated to the terminal based on whether a bit of a position corresponding to the terminal in the user bitmap is set to '1'. The method of claim 8, The process of identifying the resource allocation information code, Dividing the resource bitmap into resource allocation information codes according to the MCS type; And identifying a resource allocation information code corresponding to the rank of the bit of the position corresponding to the terminal among the bits set to '1' in the user bitmap. The method of claim 7, wherein CRC checking each of the IEs included in the map message by using a group assignment Cyclic Redundancy Check (CRC) code; Determining that the CRC check succeeded IE is the group allocation IE. A base station apparatus in a broadband wireless communication system, Determine a group to include the terminal based on at least one of a speed classification index of the terminal and a Modulation and Coding Scheme (MCS) level of the terminal, the MCS level of the terminal and the terminal according to the MCS type of the group An allocator for allocating a resource allocation information code corresponding to a resource allocation size of A generator for creating a group allocation IE (Information Element) including the resource allocation information code; And a transmitter for transmitting a group allocation IE including the resource allocation information code. The method of claim 12, The group allocation IE may include a 'GROUP ID' field for identifying a group, an MCS type indicating a type of MCS level supported by a group, a resource unit offset (RU Offset: Resource Unit offset) indicating a start position of group resources, And at least one of a user bitmap for specifying a terminal to which a group resource is allocated among the terminals belonging to the group, and a resource bitmap indicating a resource allocation information code. The method of claim 13, The generator sets a bit of a position corresponding to the at least one terminal to which the group resource is allocated in the user bitmap to '1', and the resource allocation information code allocated to the at least one terminal to which the group resource is allocated. And create the resource bitmap by concatenating. The method of claim 14, The generator may include a field in the group assignment IE to inform the terminal of an index of a bit corresponding to the terminal in the user bitmap. The method of claim 12, The apparatus further comprises a encoder for CRC processing the group assignment IE with a group assignment cyclic redundancy check (CRC) code and encoding and modulating the group assignment IE according to the lowest MCS level of the group. . The method of claim 12, The allocator, If the speed classification index of the terminal exceeds the threshold, it is determined to include the terminal in a group supporting all MCS levels, And when the speed classification index of the terminal is less than or equal to a threshold, determining that the terminal is included in the group having the highest lowest MCS level among at least one group supporting the MCS level of the terminal. A terminal device in a broadband wireless communication system, An analyzer for identifying a Modulation and Coding Scheme (MCS) type of a group and confirming a resource allocation information code assigned to the terminal according to the MCS type when a group resource is allocated through a group allocation IE (Information Element); And a manager for identifying the location of the group resource allocated to the terminal by using a resource unit offset (RU offset). The method of claim 18, The group allocation IE may include a 'GROUP ID' field for identifying a group, an MCS type indicating a type of MCS level supported by a group, a resource unit offset (RU Offset: Resource Unit offset) indicating a start position of group resources, And at least one of a user bitmap for specifying a terminal to which a group resource is allocated among the terminals belonging to the group, and a resource bitmap indicating a resource allocation information code. The method of claim 19, And the interpreter determines whether a group resource is allocated to the terminal based on whether a bit of a position corresponding to the terminal in the user bitmap is set to '1'. The method of claim 19, The interpreter divides the resource bitmap into resource allocation information codes according to the MCS type, and resource corresponding to a rank of a bit corresponding to the terminal among bits set to '1' in the user bitmap. Device for identifying the allocation information code. The method of claim 18, And a decoder for CRC checking each of the IEs included in the map message by using a group allocation Cyclic Redundancy Check (CRC) code, and determining that the IE having succeeded the CRC check is the group allocation IE. Device.

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