KR20100051526A - Method of performing bandwidth request procedure in wireless communication system - Google Patents

Abstract

PURPOSE: A method of performing a bandwidth request procedure in a wireless communication system is provided to transmit the entire MS_ID to a base station, thereby efficiently performing the bandwidth request procedure. CONSTITUTION: A terminal transmits a bandwidth request indicator and a bandwidth request message to a base station(S310). The base station transmits an ACK(Acknowledgement) signal for the bandwidth request message and the bandwidth request indicator to the terminal(S320). The base station transmits an uplink acknowledge message for uplink data(S330). The terminal transmits the uplink data through an allocated uplink radio resource(S340).

Description

Method of performing bandwidth request procedure in wireless communication system

The present invention relates to wireless communications, and more particularly, to a method for performing a bandwidth request process.

The Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard provides technologies and protocols to support broadband wireless access. Standardization has been in progress since 1999, and IEEE 802.16-2001 was approved in 2001. This is based on a single carrier physical layer called 'WirelssMAN-SC'. Later, in the IEEE 802.16a standard approved in 2003, 'WirelssMAN-OFDM' and 'WirelssMAN-OFDMA' were added to the physical layer in addition to 'WirelssMAN-SC'. After the completion of the IEEE 802.16a standard, the revised IEEE 802.16-2004 standard was approved in 2004. In order to correct bugs and errors in the IEEE 802.16-2004 standard, IEEE 802.16-2004 / Cor1 was completed in 2005 in the form of 'corrigendum'.

Currently, standardization of IEEE 802.16m, which is a new technical standard standard, is progressing based on IEEE 802.16e. IEEE 802.16m is an evolution of IEEE 802.16e.

The communication between the base station and the terminal consists of downlink (DL) transmission from the base station to the terminal and uplink (UL) transmission from the terminal to the base station. The conventional IEEE 802.16e based system profile supports a time division duplex (TDD) scheme in which downlink transmission and uplink transmission are divided into time domains. The TDD scheme is a scheme in which uplink transmission and downlink transmission are performed at different times while using the same frequency band. The TDD scheme has an advantage of easy frequency selective scheduling because the uplink channel characteristic and the downlink channel characteristic are reciprocal. In IEEE 802.16m, not only the TDD scheme but also the frequency division duplex (FDD) scheme are considered. In the FDD scheme, downlink transmission and uplink transmission are simultaneously performed through different frequency bands. In IEEE 802.16e, a 5 ms frame of a TDD scheme is used, whereas in IEEE 802.16m, a 20 ms super-frame for a TDD scheme and an FDD scheme is considered.

In IEEE 802.16e, the terminal performs a bandwidth request (BW REQ) process to the base station when there is data to be transmitted in the uplink. The bandwidth request process in IEEE 802.16e includes (1) transmission of bandwidth request indicator, (2) transmission of response message for bandwidth request indicator, (3) transmission of bandwidth request message, (4) transmission of uplink grant message, and (5) uplink. It is a five-step process involving link data transmission. The bandwidth request indicator is selected from one of predetermined orthogonal codes and transmitted through a contention-based channel. If the bandwidth request indicator transmitted by the terminal does not collide with the bandwidth request indicator of the other terminal, the base station transmits an UL grant message for the transmission of the bandwidth request message in response to the bandwidth request indicator. Table 1 shows an example of an uplink grant message for transmission of a bandwidth request message.

Syntax Size (bit) Notes CDMA_Allocation_IE0 { - -   Duration 6 -   UIUC 4 UIUC for transmission   Repetition Coding Indication 2 0b00: No repetition coding 0b01: Repetition coding of 2 used 0b10: Repetition coding of 4 used 0b11: Repetition coding of 6 used   Frame Number Index 4 LSBs of relevant frame number   Ranging code 8 -   Ranging Symbol 8 -   Ranging subchannel 7 -   BW request mandatory One 1: Yes 0: No } - -

The terminal receiving the uplink grant message transmits the bandwidth request message through the determined radio resource. The bandwidth request message includes information such as a connection identifier (CID) of the terminal and a request radio resource size.

Upon receiving the bandwidth request message, the base station transmits an uplink grant message including the size and location information of the uplink radio resource for uplink data transmission to the terminal having the corresponding CID. Table 2 shows an example of an uplink grant message for uplink data transmission.

Syntax Size (bit) Notes UL-MAP_IE0 { -   CID 16 -   Start time 11 -   Subchannel index 5 -   UIUC 4 -   Duration 10 In OFDM symbols   Midamble repetition interval 2 0b00: Preamble only 0b01: Interval 5: Midamble after every 4 data 0b10: Interval 9: Midamble after every 8 data 0b11: Interval 17: Midamble after every 16 data symbols   if (UIUC == 4) -     Focused_Contention_IE () 16 -   if (UIUC == 13) -     Subchannelized_Network_Entry_IE () 12 -   if (UIUC == 15) -     UL_Extended_IE () variable See subclause   Padding nibble, if needed 4 Completing to nearest byte, shall be set to 0x0 } - -

The terminal transmits uplink data through an uplink radio resource indicated by an uplink grant message for uplink data transmission. The uplink data is transmitted with a header including a CID of the terminal and a cyclic redundancy check (CRC) for error checking the data.

In IEEE 802.16m, E-MBS (Enhanced Multicast Broadcast Service) for various multimedia services, multi-hop relay for service improvement in shadow area, femto-cell for high capacity service in home or office Various communication service technologies such as) are being introduced. Macro cells, relay base stations and femtocells may use different frequency bands for interference mitigation. If a large number of relay base stations or femtocells are arranged in a macro-cell, hand-to-cell handovers of the terminal are more frequent. Accordingly, the terminal performs a bandwidth request process more frequently. In addition, in continuously providing a high-capacity real-time service such as video communication, delay of the bandwidth request process may cause a deterioration of service quality.

In order to improve the quality of service of a wireless communication system, a more efficient method of performing a bandwidth request process is required.

An object of the present invention is to provide a method for more efficiently performing the bandwidth request process.

In a method for performing a bandwidth request process in a wireless communication system according to an aspect of the present invention, transmitting a bandwidth request indicator and a bandwidth request message through a bandwidth request channel, and upward in response to the bandwidth request indicator and the bandwidth request message. Receiving an uplink grant message indicating a link radio resource, and transmitting uplink data after receiving the uplink grant message, wherein the uplink grant message includes type information of the uplink grant message. It includes.

In a wireless communication system according to another aspect of the present invention, a method for performing a bandwidth request process includes: transmitting a bandwidth request message including a bandwidth request indicator and a partial ID of a terminal consisting of some bits of the entire ID of the terminal through a bandwidth request channel; Receiving an uplink grant message indicating an uplink radio resource in response to the bandwidth request indicator and the bandwidth request message, and transmitting uplink data through the uplink radio resource; The uplink data includes a remaining portion of the entire ID of the terminal except for the partial ID of the terminal.

The bandwidth request process can be performed more quickly and efficiently.

The following techniques include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier frequency division multiple access (SC-FDMA), and the like. It can be used in various wireless communication systems. CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16e (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA), and the like. UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) long term evolution (LTE) is part of an Evolved UMTS (E-UMTS) using E-UTRA, and employs OFDMA in downlink and SC-FDMA in uplink. IEEE 802.16m is an evolution of IEEE 802.16e.

For clarity, the following description focuses on IEEE 802.16m, but the technical spirit of the present invention is not limited thereto.

1 shows a wireless communication system.

Referring to FIG. 1, a wireless communication system includes at least one base station 20 (BS). Each base station 20 provides a communication service for a particular geographic area (generally called a cell). The cell may again be divided into multiple regions (referred to as sectors). A mobile station (MS) 10 may be fixed or mobile, and may include a user equipment (UE), a user terminal (UT), a subscriber station (SS), a wireless device, a personal digital assistant (PDA), It may be called other terms such as a wireless modem and a handheld device. The base station 20 generally refers to a fixed station communicating with the terminal 10, and may be referred to as other terms such as an evolved-NodeB (eNB), a base transceiver system (BTS), and an access point. have.

Hereinafter, downlink (DL) means communication from the base station to the terminal, and uplink (UL) means communication from the terminal to the base station. In downlink, a transmitter may be part of a base station and a receiver may be part of a terminal. In uplink, a transmitter may be part of a terminal and a receiver may be part of a base station.

2 shows an example of a frame structure.

Referring to FIG. 2, a superframe includes a superframe header and four frames (frames, F0, F1, F2, and F3). The size of each superframe is 20ms and the size of each frame is illustrated as 5ms, but is not limited thereto. The superframe header may be placed at the front of the superframe, and a common control channel is assigned. The common control channel is a channel used for transmitting control information that can be commonly used by all terminals in a cell, such as information on frames or system information of a superframe.

 One frame includes eight subframes (Subframe, SF0, SF1, SF2, SF3, SF4, SF5, SF6, SF7). Each subframe may be used for uplink or downlink transmission. The subframe may consist of 6 or 7 OFDM symbols, but this is only an example. A time division duplexing (TDD) scheme or a frequency division duplexing (FDD) scheme may be applied to the frame. In the TDD scheme, each subframe is used for uplink transmission or downlink transmission at different times at the same frequency. That is, the subframes in the frame of the TDD scheme are classified into an uplink subframe and a downlink subframe in the time domain. In the FDD scheme, each subframe is used for uplink transmission or downlink transmission at different frequencies at the same time. That is, subframes in the frame of the FDD scheme are divided into an uplink subframe and a downlink subframe in the frequency domain. Uplink transmission and downlink transmission occupy different frequency bands and may be simultaneously performed.

The subframe includes at least one frequency partition. The frequency partition is composed of at least one Physical Resource Unit (PRU). The frequency partitions may include Localized PRUs and / or Distributed PRUs. Frequency partitioning may be used for other purposes such as Fractional Frequency Reuse (FFR) or Multicast and Broadcast Services (MBS).

A PRU is defined as a basic physical unit for resource allocation that includes a plurality of consecutive OFDM symbols and a plurality of consecutive subcarriers. The number of OFDM symbols included in the PRU may be equal to the number of OFDM symbols included in one subframe. For example, when one subframe consists of 6 OFDM symbols, the PRU may be defined with 18 subcarriers and 6 OFDM symbols. Logical Resource Units (LRUs) are basic logical units for distributed resource allocation and localized resource allocation. The LRU is defined by a plurality of OFDM symbols and a plurality of subcarriers and includes pilots used in a PRU. Thus, the appropriate number of subcarriers in one LRU depends on the number of pilots assigned.

Logical Distributed Resource Units (DRUs) may be used to obtain frequency diversity gain. The DRU includes subcarrier groups distributed in one frequency partition. The size of the DRU is equal to the size of the PRU. The smallest unit that forms a DRU is one subcarrier.

Logical Contiguous Resource Units (CRUs) may be used to obtain frequency selective scheduling gains. The CRU includes a local subcarrier group. The size of the CRU is equal to the size of the PRU.

Now, the bandwidth request process will be described. The bandwidth request process is a process in which a terminal requests to allocate an uplink radio resource to a base station for uplink transmission. The UE may transmit uplink data by receiving an uplink radio resource through a bandwidth request process.

<Uplink data transmission after power on or handover of terminal>

3 illustrates a process of transmitting uplink data according to an embodiment of the present invention.

Referring to FIG. 3, when the terminal is powered on or performs a handover from an adjacent cell in the cell area of the base station, the terminal is given an MS_ID for identification of the terminal and a flow ID for connecting to a specific service from the base station. (S110). The flow ID refers to an ID of a service used by the terminal to set up a specific service (eg, voice call, video call, control information transmission, etc.). Since various services may be provided to one terminal, the terminal may be given a plurality of Flow IDs. Flow ID may indicate the periodicity of service.

The UE performs a contention based BW REQ process (S120). The contention-based bandwidth request process is performed by transmitting a sequence randomly selected by a terminal from a predetermined orthogonal code through a bandwidth request channel (BW REQ channel) defined competitively with another terminal. The bandwidth request channel includes a radio resource through which the terminal can send a bandwidth request sequence and a bandwidth request message. The bandwidth request channel includes a plurality of bandwidth request tiles. The bandwidth request tile may be distributed in the frequency domain or the time domain. The bandwidth request tile is composed of a plurality of consecutive subcarriers on a plurality of OFDM symbols. For example, the bandwidth request channel may include three distributed bandwidth request tiles. The bandwidth request tile may be defined as six consecutive subcarriers on 6 OFDM symbols. The contention-based bandwidth request process includes a 3 step BW REQ process and a 5 step BW REQ process. The 3-step bandwidth request process is a method of transmitting uplink data faster by reducing the 5-step bandwidth request process. If the 5-step bandwidth request process is a general bandwidth request process, the 3-step bandwidth request process may be referred to as a fast bandwidth request process. The procedure for performing the 3-step bandwidth request process and the 5-step bandwidth request process will be described later. Through the contention-based bandwidth request process, the terminal may transmit uplink data by receiving an uplink radio resource. If the period and data size of the service corresponding to the flow ID received by the terminal are fixed, the base station may directly allocate an uplink radio resource without a bandwidth request of the terminal.

After transmitting uplink data to the base station, the UE transmits uplink data afterward using a contention based bandwidth request process, a non-contention based BW REQ process, or polling information (Polling information element). It may be (S130). The contention-free bandwidth request process is performed when the base station knows in advance the sequence to be used for the bandwidth request by the terminal or when a specific radio resource is designated for the bandwidth request so that the terminal can perform the bandwidth request without competition with other terminals. do. Polling information is information provided periodically about a quality of service (QoS) and traffic characteristics (traffic characteristics) for uplink transmission. If the terminal transmitting the uplink data is data of a flow corresponding to a service without periodicity, the terminal transmits uplink data by performing a contention-based bandwidth request process again. If the uplink data to be transmitted by the terminal is data of a flow corresponding to a periodic service or the size of the data is changed, the base station specifies a radio resource for the non-competition based bandwidth request to the terminal or transmits a bandwidth request header using polling information. You can do that. Services that have periodicity or change in data size include a streaming service or a real time service such as a real time polling service (rtPS) or an extended real time polling service (ertPS).

As such, since the UE may perform a contention-free bandwidth request or a bandwidth request using polling information without performing a contention-based bandwidth request process for uplink data to be transmitted later, a bandwidth request that may occur in the contention-based bandwidth request process The delay caused by failure can be prevented. In the contention-free bandwidth request process, a separate radio resource must be allocated to the terminal, which may result in overhead. A three-step bandwidth request process may be performed to reduce overhead that may occur in a contention-free bandwidth request process and to reduce delay of the bandwidth request process.

Now, the procedure of the 5-step bandwidth request process and the 3-step bandwidth request process will be described.

<Process of 5-step Bandwidth Request Process>

4 is a flowchart illustrating a five-step bandwidth request procedure according to an embodiment of the present invention.

4, the terminal sends a bandwidth request indicator to the base station (S210). The bandwidth request indicator may be arbitrarily selected from a predetermined set of orthogonal or semi-orthogonal codes. The kind, length, etc. of the orthogonal or quasi-orthogonal codes used as the bandwidth request indicator are not limited, and orthogonal or quasi-orthogonal code sets may be provided in plural, and different orthogonal or quasi-orthogonal code sets may be used according to cells or sectors. have. The terminal may transmit a first bandwidth request message including information required for bandwidth allocation with the bandwidth request indicator. Information required for bandwidth allocation includes MS_ID, Flow ID, and scheduling type. The first bandwidth request message transmitted with the bandwidth request indicator in the 5-step bandwidth request process may include some of information required for bandwidth allocation or may be included in a reduced form. The first bandwidth request message may include the entire MS_ID or some MS_ID. Some MS_IDs may be configured in such a manner that some bits are omitted from the least significant bit (LSB) or the most significant bit (MSB) in all MS_IDs. The bandwidth request indicator can be transmitted through a contention-based bandwidth request channel. The first bandwidth request message may be a message of a media access control (MAC) layer that is a higher layer of the physical layer.

The base station may correlate the entire orthogonal or quasi-orthogonal code set with the bandwidth request indicator received from the terminal to find a sequence selected by the terminal based on a specific threshold value. The bandwidth request indicator may not be transmitted through the predefined bandwidth request channel, and one or more bandwidth request indicators may be transmitted. The base station finds a first bandwidth request message for the bandwidth request indicator. When the first bandwidth request message includes the CRC, it is determined whether the first bandwidth request message is an error through the CRC. If CRC is not included in the first bandwidth request message, whether an error of the first bandwidth request message may be determined through a received signal strength indication (RSSI) or a carrier to interference ratio (CINR).

If the first bandwidth request message for the bandwidth request indicator is not received or an error occurs, the base station may perform a 5-step bandwidth request process. That is, the terminal performs the bandwidth request process with only the bandwidth request indicator. When the first bandwidth request message for the bandwidth request indicator is received without error, the base station may perform a 5-step bandwidth request process or a 3-step bandwidth request process. Here, a case where the 5-step bandwidth request process is performed will be described.

The base station may send an ACK (Acknowledgement) signal for the bandwidth request indicator to the terminal (S220). The ACK signal may be transmitted or omitted at a predetermined period.

The base station transmits an UL grant message (UL grant message) (S230). If the base station detects only the bandwidth request indicator, it transmits an uplink grant message for the second bandwidth request message. Hereinafter, the uplink grant message for the second bandwidth request message is called a control grant message. The control approval message may include the information shown in Table 3.

Information note UL grant type  UL grant when only a bandwidth request indicator is detected. confirm BW REQ indicator  Sequence index and area information of the received BW REQ indicator resource for BW REQ message  BW REQ header area or non-competition based BW REQ area CRC or Broadcast MS_ID  MS_ID or UL grant type masking

The control acknowledgment message includes (1) type information of the uplink grant message, (2) acknowledgment information for the bandwidth request indicator, (3) uplink radio resource allocation information for the second bandwidth request message, and (4) CRC. Can be.

The type information of the uplink grant message is information for identifying the type of grant message used in the 5-step bandwidth request process and the 3-step bandwidth request process. Here, the type information of the uplink grant message indicates that the uplink grant message is an uplink grant message for the case where only the bandwidth request indicator is detected. The type information of the uplink grant message may be transmitted through a separate resource region or may be transmitted by masking the CRC. For example, when a 12-bit MS_ID is masked on a 16-bit CRC, the type information of the uplink grant message may be masked and transmitted on the remaining 4 bits.

The confirmation information about the bandwidth request indicator indicates the sequence index, resource region, etc. of the bandwidth request indicator received by the base station. Orthogonal or quasi-orthogonal code sets used as bandwidth request indicators can be divided into various uses, and bandwidth request indicators can indicate additional information about the use of orthogonal or quasi-orthogonal code sets. For example, when the orthogonal or quasi-orthogonal code set of the bandwidth request indicator is used according to the 5-step bandwidth request process and the 3-step bandwidth request process, the confirmation information about the bandwidth request indicator is a threshold for the division of the bandwidth request process. The value may indicate whether a bandwidth request process to be performed later is a 3-step bandwidth request process or a 5-step bandwidth request process.

The uplink radio resource allocation information for the second bandwidth request message indicates a resource region for transmitting a header of the bandwidth request message to be transmitted later by the terminal, or transmits a contention-free bandwidth request message in a non-competition based bandwidth request process. It can represent a resource area.

The CRC is for detecting whether an acknowledgment message for control is in error, and information on the type of MS_ID or uplink grant message may be masked in the CRC. The base station does not know the MS_ID of the terminal because the terminal did not transmit the first bandwidth request message or an error occurred in the first bandwidth request message. The base station may not mask the MS_ID in the CRC or may mask the broadcast MS_ID. The broadcast MS_ID is an MS_ID randomly assigned to the terminal in order to perform a subsequent bandwidth request process. If the broadcast MS_ID is not masked in the CRC or if the bits of the broadcast MS_ID are smaller than the bits of the CRC, the type information of the uplink grant message included in the control acknowledgment message may be masked in the CRC.

The terminal transmits the second bandwidth request message through the allocated uplink radio resource through the control approval message (S240). The second bandwidth request message may be a message of the MAC layer. The second bandwidth request message may include all of information required for bandwidth allocation or may include remaining information not included in the first bandwidth request message. The second bandwidth request message may include a total MS_ID, a flow ID, a size of a requesting radio resource, a scheduling type, and the like.

The base station may send an ACK signal for the second bandwidth request message (S250). The ACK signal may be transmitted or omitted at a predetermined period.

The base station transmits an uplink grant message for uplink data (S260). Hereinafter, an uplink grant message for uplink data is referred to as a grant message for data. In the 5-step bandwidth request process, the authorization message for data may include information as shown in Table 4.

Information note UL grant type  UL grant for UL data trasmission confirm BW REQ message  Confirmation of received BW REQ message and request radio resource resource for UL data  Location and Size of Uplink Radio Resource for UL Data Transmission CRC or Broadcast MS_ID  MS_ID or UL grant type masking

The acknowledgment message for data may include (1) type information of the uplink acknowledgment message, (2) acknowledgment information on the bandwidth request message, (3) uplink radio resource allocation information on the uplink data, and (4) CRC. have.

The type information of the uplink grant message indicates that the uplink grant message is for uplink data transmission. The type information of the uplink grant message may be transmitted through a separate resource region or may be transmitted by masking the CRC. The confirmation information on the bandwidth request message indicates whether the MS_ID, Flow ID, size of the requesting radio resource, scheduling type, etc., included in the bandwidth request message received by the base station. The uplink radio resource allocation information for uplink data indicates the position and size of an uplink radio resource allocated to the terminal by reflecting the size of the radio resource requested by the terminal. The CRC is for detecting whether an acknowledgment message for data is an error, and the entire information of the MS_ID or the type of the uplink grant message may be masked in the CRC. If the bits of the entire MS_ID are smaller than the bits of the CRC, the type information of the uplink grant message included in the grant message for data may be masked in the CRC.

The terminal transmits uplink data through the uplink radio resource allocated through the data approval message (S270). The uplink data may not include the entire MS_ID. Since the base station knows the entire MS_ID of the terminal, the entire MS_ID does not need to be transmitted separately.

Even when the terminal sends only the bandwidth request indicator, the three-step bandwidth request process may be performed in the following cases.

(1) This is a case where the UE arbitrarily performs a three-step bandwidth request process. When the base station transmits an uplink grant message for the second bandwidth request message, the terminal may optionally transmit uplink data instead of the second bandwidth request message. In this case, the base station may determine whether the second bandwidth request message or the uplink data by looking at the header type (header type) of the data transmitted by the terminal. Therefore, the step S240 to step S260 may be omitted so that a three-step bandwidth request process may be performed.

(2) The base station arbitrarily performs a three-step bandwidth request process. Instead of transmitting an uplink grant message (control grant message) for the second bandwidth request message, the base station may optionally transmit a grant message for data. The terminal may determine whether the control approval message or the data approval message through the type information of the uplink approval message. Therefore, the step S230 to step S250 may be omitted so that a three-step bandwidth request process may be performed.

<3. Bandwidth Request Process>

5 is a flowchart illustrating a three-step bandwidth request procedure according to an embodiment of the present invention.

Referring to FIG. 5, the terminal sends a bandwidth request indicator and a bandwidth request message to the base station (S310). The bandwidth request indicator and the bandwidth request message can be sent over a contention based bandwidth request channel. The bandwidth request indicator may be arbitrarily selected from a predetermined orthogonal or quasi-orthogonal code set. Since transmitting a large amount of information through a contention-based bandwidth request channel may waste radio resources, the bandwidth request message should include the minimum information necessary for bandwidth allocation. The bandwidth request message may include an MS_ID, a QoS ID, a flow ID, a buffer size indicating a size of a requesting radio resource, a reception power level, and the like. The OoS ID is a QoS index composed of scheduling type and priority of bandwidth request. The bandwidth request message may include the entire MS_ID or some MS_ID. Some MS_IDs consist of some bits in the entire MS_ID. That is, some MS_IDs may be configured in such a manner that some bits are omitted from the LSB or the MSB in all MS_IDs.

The base station may correlate the entire orthogonal or quasi-orthogonal code set to the bandwidth request indicator received from the terminal to find the orthogonal or quasi-orthogonal code selected by the terminal. The bandwidth request indicator may not be transmitted through the predefined bandwidth request channel, and one or more bandwidth request indicators may be transmitted. The base station finds a bandwidth request message for the bandwidth request indicator. The base station may use the bandwidth request indicator to estimate and demodulate the channel for the bandwidth request message. If the CRC is included in the bandwidth request message, it is determined whether the bandwidth request message is an error through the CRC. When the CRC is not included in the bandwidth request message, whether an error of the bandwidth request message may be determined through RSSI or CINR. If the bandwidth request message is received without error, the base station performs a three-step bandwidth request process.

The base station may send an ACK signal for the bandwidth request indicator and the bandwidth request message to the terminal (S320). The ACK signal may be transmitted or omitted at a predetermined period.

The base station transmits an uplink grant message for uplink data (S330). The uplink grant message for uplink data may be referred to as a grant message for data. The base station generates and transmits an acknowledgment message for data using the information included in the bandwidth request message transmitted by the terminal. In the 3-step bandwidth request process, the authorization message for data may include information as shown in Table 5.

Information note UL grant type  UL grant when both a bandwidth request indicator and a message are detected. confirm BW REQ indicator and message  Sequence index, MS_ID, area information of received BW REQ indicator resource for UL data  Location and Size of Uplink Radio Resource for UL Data Transmission CRC or Broadcast MS_ID  MS_ID or UL grant type masking

In the 3-step bandwidth request process, the acknowledgment message for data includes (1) type information of the uplink grant message, (2) confirmation information on the bandwidth request indicator and the bandwidth request message, and (3) uplink radio resource allocation for the uplink data. Information, (4) CRC, and the like.

The type information of the uplink grant message indicates that the uplink grant message is a case where a bandwidth request indicator and a bandwidth request message are detected. The type information of the uplink grant message may be transmitted through a separate resource region or may be transmitted by masking the CRC. For example, when a 12-bit MS_ID is masked on a 16-bit CRC, the type information of the uplink grant message may be masked and transmitted on the remaining 4 bits.

The confirmation information for the bandwidth request indicator and the bandwidth request message includes information about the sequence index of the bandwidth request indicator received by the base station, the total MS_ID or some MS_ID received, the Flow ID, the size of the requesting radio resource, the scheduling type, and the received bandwidth request. Indicates a resource area (e.g., bandwidth request indicator and frame number to which the message was sent).

The uplink radio resource allocation information for uplink data indicates the position and size of an uplink radio resource allocated to the terminal by reflecting the size of the radio resource requested by the terminal.

The CRC is for detecting whether an acknowledgment message for data is in error. The CRC may be masked with MS_ID or type information of an uplink acknowledgment message. If the base station knows the entire MS_ID, the entire MS_ID may be masked in the CRC. If the base station knows only some MS_IDs, only some MS_IDs may be masked in the CRC, or the remainder of some MS_IDs together with some MS_IDs may be masked in the CRC with a predetermined value (eg, 0). If the bits of the entire MS_ID are smaller than the bits of the CRC, the type information of the uplink grant message included in the grant message for the data of the 3rd bandwidth request may be masked in the CRC.

The terminal transmits uplink data through the uplink radio resource allocated through the data approval message (S340). The terminal receives the uplink grant message and transmits uplink data through a radio resource indicated by the base station if the frame number, sequence index, etc. of the bandwidth request message transmitted by the terminal match. When the terminal includes the entire MS_ID in the bandwidth request message and transmits it, the terminal does not need to include the entire MS_ID in the uplink data. However, when the terminal includes only some MS_IDs in the bandwidth request message and transmits it, the terminal should inform the entire MS_ID from the base station. When performing a three-step bandwidth request process using some MS_IDs, although the entire MS_IDs are different, some MS_IDs are the same, which may cause collision with other terminals. For example, if the flow ID or scheduling type included in the bandwidth request message is different, or if the transmission frame number or sequence index is different, it may be distinguished. However, if all the information is the same and there is a terminal different from the entire MS_ID, the base station cannot decode the bandwidth request message, and the terminal must retry the 3rd bandwidth request process or perform the 5th bandwidth request process. Accordingly, a delay of the bandwidth request process may occur.

In order to prevent this, the UE may inform the base station of the entire MS_ID by adding an extended header including the entire MS_ID or the remaining part except the partial MS_ID in the entire MS_ID. That is, the format of the uplink data may vary depending on whether the entire MS_ID is included in the bandwidth request message during the bandwidth request process. In addition, the format of the uplink data may vary depending on whether the base station recognizes the MS_ID (Station ID) of the terminal to which the uplink bandwidth is to be allocated.

<Format of Uplink Data in Bandwidth Request Process>

6 shows an example of an uplink data format used in a bandwidth request process.

Referring to FIG. 6, when the entire MS_ID is included in the bandwidth request message and transmitted in the 5-step bandwidth request process or the 3-step bandwidth request process, the base station may know the full MS_ID of the terminal. Accordingly, when the base station allocates the MS to the corresponding UE while recognizing the MS_ID of the terminal to which the uplink resource is allocated, the terminal does not need to separately inform the entire MS_ID when the uplink data is transmitted. The terminal transmits the uplink data by including a generic MAC header and a CRC.

The generic MAC header is used for the transmission of general data. The general MAC header includes a plurality of fields and may be used for downlink transmission as well as uplink transmission. Fields included in the general MAC header include a header type (HT), an extended header presence indicator (EH), a flow ID, an encryption key sequence (EKS), a length, and the like. HT indicates the type of header. The EH indicates the presence or absence of an extension header following the general MAC header. Flow ID indicates an address of a flow, EKS indicates an encryption sequence, and Length indicates a length of a payload. The numbers in parentheses in each field indicate the number of bits in each field. The number of bits in each field is not limited.

7 shows another example of an uplink data format used in a bandwidth request process.

Referring to FIG. 7, if a partial MS_ID is included in the bandwidth request message or is not included at all, the BS cannot know the entire MS_ID of the UE. And even when only the bandwidth request indicator is transmitted in the 5-step bandwidth request, the base station cannot know the MS_ID of the terminal. Therefore, the terminal should inform the base station of the entire MS_ID during uplink data transmission. The terminal transmits the uplink data by including the general MAC header, the extension header, and the CRC.

Whether to include the extension header is indicated by the EH field of the general MAC header. The extended header includes fields such as Last, Type, Body Content, and the like. Last indicates whether the extension header is the last extension header. The uplink data may include a plurality of extension headers and may indicate that the last extension header is the last extension header because the last field is not provided. Type indicates the type of extension header, and Body Content includes various information according to the type. The length of the body content can be changed in various ways depending on the information included.

When including the entire MS_ID in the uplink data, the entire MS_ID may be included in the Body Content field of the extension header. Alternatively, when the uplink data includes the remaining portion except for the partial MS_ID in the entire MS_ID, the remaining MS_ID may be included in the Body Content field of the extension header. The type of MS_ID included in the Body Content field may be indicated according to the type of the Type field. When uplink data is transmitted, when additional uplink radio resources are needed, the terminal may transmit the size of the required bandwidth along with the entire MS_ID in the extension header. The amount of bandwidth required can also be included in the Body Content field and can be indicated according to the type of the Type field.

In the three-stage bandwidth request process, only UEs that have transmitted some MS_IDs through the contention-based bandwidth request channel and have been allocated uplink radio resources through the contention-based bandwidth request channel are not uplinked. It may be more efficient to send all or the remaining MS_IDs to the data.

<Process of bandwidth request process considering reliability of bandwidth request indicator>

The UE which is initially connected or handed over or which has been in an idle state for a long time does not know the information about Signal to Interference plus Noise Ratio (SINR) accurately due to inaccuracy of power control, and thus is appropriate for correlation of bandwidth request indicators. The threshold may not be estimated. This may degrade the detection performance of the bandwidth request indicator in the 5-step bandwidth request process or the 3-step bandwidth request process. In particular, in the three-step bandwidth request process in which a channel for a bandwidth request message is estimated and demodulated using the detected bandwidth request indicator, severe performance degradation may be caused. In order to prevent performance degradation of the bandwidth request process, the amount of information included in the bandwidth request message transmitted with the bandwidth request indicator should be minimized.

8 shows a procedure of performing a bandwidth request process for minimizing the amount of information of a bandwidth request message according to an embodiment of the present invention.

Referring to FIG. 8, the terminal sends a bandwidth request indicator and a bandwidth request message to the base station (S410). In order to ensure the reliability of the estimated performance for the bandwidth request indicator, the bandwidth request message includes minimal information. For example, the bandwidth request message may include at least one of a QoS ID or a buffer size and a CRC. OoS ID is a QoS index composed of scheduling type and priority of bandwidth request. The buffer size indicates the size of radio resources requested by the terminal. That is, MS_ID or Flow ID of the terminal is not included in the bandwidth request message. Therefore, the base station performs the bandwidth request process without knowing the terminal requesting the bandwidth.

The base station may send an ACK signal for the bandwidth request indicator and the bandwidth request message to the terminal (S420). The ACK signal may be transmitted or omitted at a predetermined period.

Since the base station cannot know which UE transmits the bandwidth request indicator using a sequence, the base station performs a CRC check on all orthogonal or quasi-orthogonal codes used as the bandwidth request indicator.

If a CRC error is not detected for a particular orthogonal or quasi-orthogonal code, an uplink that includes information on the received bandwidth request message (QoS ID or buffer size) along with when the orthogonal or quasi-orthogonal code and the bandwidth request indicator were transmitted. The approval message is transmitted (S430). The time point at which the bandwidth request indicator is transmitted may be expressed by at least one of a frame number, a slot, a transmission opportunity, a subframe number, and a bandwidth request channel index.

The uplink grant message may be transmitted at any time or at a fixed time. (1) When an uplink grant message is transmitted at an arbitrary time point, the uplink grant message includes a frame number, a slot, and a transmission opportunity in the uplink grant message so that the UE knows its uplink grant message. opportunity), at least one of a subframe number and a bandwidth request channel index. (2) When the uplink grant message is transmitted at a fixed time point, the UE may know when the uplink grant message is transmitted if only the information such as the transmission opportunity or the bandwidth request channel index is known.

The terminal receives the uplink grant message and transmits uplink data through the uplink radio resource indicated by the base station when the bandwidth request message, the transmission time point, and the sequence thereof are identical (S440). The header of the uplink data includes MS_ID and Flow ID of the terminal and is transmitted. The general MAC header of the uplink data may include a Flow ID and the extension header may include the MS_ID of the terminal. The base station can know the terminal requesting the bandwidth through the MS_ID and Flow ID included in the uplink data. If there is uplink data to be transmitted later, the UE may piggyback a bandwidth request message on the uplink data and send it together.

On the other hand, although the CRC error for the bandwidth request message is not detected, the base station may send an ACK signal when there is no radio resource to be allocated immediately. Since the base station does not know which terminal requests bandwidth, (1) broadcasts the corresponding sequence and bandwidth request message through a separate channel, or (2) a predetermined value of an uplink grant message (eg, 00. ..0), or (3) an uplink grant message may include an indicator for an ACK signal (for example, 0 for data transmission after a predetermined time and 1 for immediate transmission).

As such, the base station may improve the reliability of the bandwidth request indicator and the bandwidth request message by performing a bandwidth request process without knowing the terminal requesting the bandwidth. In addition, since only the minimum information is included in the bandwidth request message, the decoding burden of the bandwidth request message can be reduced, and the execution period of the bandwidth request process can be reduced. If multiple terminals simultaneously transmit a bandwidth request message including the same information, collision between terminals may occur, but the sequence index used as the bandwidth request indicator and the QoS ID or buffer size included in the bandwidth request message are the same. Rarely occurs. Therefore, the bandwidth request process may be performed more accurately and faster than the performance degradation due to the reliability problem of detection of the bandwidth request indicator or the collision problem of the bandwidth request indicator due to the UE not estimating an appropriate threshold value for correlation of the bandwidth request indicator. have. In addition, even if there are two or more terminals using the same bandwidth request indicator, when there is at least one terminal that succeeds in the CRC check, a normal three-step bandwidth request process may be performed. If an error occurs in the CRC check for the bandwidth request message, the base station may perform a 5-step bandwidth request process through a bandwidth request indicator detection method using a threshold value.

In performing the 5-step bandwidth request process, the UE may transmit the MS-ID without including the MS_ID in the first bandwidth request message. That is, the base station may perform a 5-step bandwidth request process without knowing the terminal requesting the bandwidth. In this case, the terminal may transmit its MS_ID by including the second bandwidth request message or uplink data. In the 5-step bandwidth request process, the reliability of the bandwidth request indicator and the bandwidth request message can be improved.

<Selection of bandwidth request process>

As described above, the three-step bandwidth request process is for performing a faster bandwidth request, and the five-step bandwidth request process is for more stably performing a contention-based bandwidth request process. The subject that determines which bandwidth request process to perform may be a base station or a terminal.

9 illustrates a method of selecting a bandwidth request process according to an embodiment of the present invention.

Referring to FIG. 9, the terminal sends a bandwidth request message together with the bandwidth request indicator or the bandwidth request indicator to the base station to request the bandwidth (S510). In step 3 of the bandwidth request process, the UE sends a bandwidth request indicator and a bandwidth request message. In the 5-step bandwidth request process, the UE sends only a bandwidth request indicator or a bandwidth request message with the bandwidth request indicator.

The base station may select and perform a three-step bandwidth request process or a five-step bandwidth request process through the bandwidth request indicator or the bandwidth request message received from the terminal (S520). The terminal may select a desired bandwidth request process in the process of transmitting the bandwidth request indicator or the bandwidth request message, and the base station may select a bandwidth request process to be performed in the process of receiving the bandwidth request indicator or the bandwidth request message.

Table 6 shows an example of the criteria for the base station or the terminal to select the bandwidth request process.

Selected subject Selection criteria Bandwidth Request Process Base station Receive Status of Bandwidth Request Indicators and Messages Step 3: Receive bandwidth request indicator and message or receive bandwidth request indicator only Step 5: Receive bandwidth request indicator only Terminal Whether to send a bandwidth request message Step 3: Send Bandwidth Request Indicators and Messages or Send Bandwidth Request Indicators Only Step 5: Send Bandwidth Request Indicators Only Delimit a subset of bandwidth request indicators Classification according to service type Step 3: Send sequence for real-time service Step 5: Send sequence for non-real-time service According to the random choice Step 3: Send sequence for 3 step bandwidth request Step 5: Send sequence for step 5 bandwidth request

When the bandwidth request message is transmitted with the bandwidth request indicator, the base station may determine the bandwidth request process by checking the reception status of the bandwidth request indicator and the bandwidth request message. If a bandwidth request message is received with the bandwidth request indicator, a three-step bandwidth request process is performed. When only the bandwidth request indicator is received, for example, when the terminal transmits only the bandwidth request indicator or when an error occurs in the bandwidth request message and the base station can detect only the bandwidth request indicator, the 5-step bandwidth request process is selected. do. Alternatively, the base station or the terminal may arbitrarily select a three-step bandwidth request process. Of course, if the base station is unable to receive both the bandwidth request indicator and the bandwidth request message, the bandwidth request process has failed, and the terminal retries the bandwidth request process.

When the terminal desires to perform the three-step bandwidth request process, the terminal transmits only the bandwidth request indicator, and when the terminal desires to perform the five-step bandwidth request process, the terminal may transmit the bandwidth request message together with the bandwidth request indicator to determine the bandwidth request process.

Orthogonal or quasi-orthogonal codes are used as the sequence of bandwidth request indicators. Accordingly, the bandwidth request indicator can be transmitted in a code division multiplexing (CDM) scheme on the bandwidth request channel, and the sequence of the bandwidth request indicator can be easily distinguished. Code sets used as bandwidth request indicators may be divided into subsets for determining a bandwidth request process.

The subset of bandwidth request indicators can be divided according to service type. For example, there are two types of services, real-time services such as Voice over Internet Protocol (VoIP) and non-real-time services such as general data services. The subset of bandwidth request indicators can be divided into sequences for real-time services and sequences for non-real-time services. Real-time services are sensitive to delay, and non-real-time services are relatively insensitive to delay. For bandwidth-sensitive services, a faster bandwidth request process needs to be performed. Accordingly, the terminal may select and send a sequence for a real time service if its service is a delay sensitive service, and select and send a sequence for a non real time service for a service that is not sensitive to delay. That is, the terminal may select and send a subset of the bandwidth request indicators according to its service type. When the sequence for the non-real-time service is transmitted from the terminal, the base station may perform a 5-step bandwidth request process. When the sequence for the real-time service is transmitted from the terminal, the base station may perform a three-step bandwidth request process. When a data packet of a predetermined size is used, such as VoIP, the base station may perform a three-step bandwidth request process by allocating a radio resource of a predetermined specific size.

The subset of bandwidth request indicators may be divided into a three-step bandwidth request sequence and a five-step bandwidth request sequence. The classification information of the 3rd bandwidth request sequence and the 5th bandwidth request sequence or the index information of the divided sequence may be broadcast. The terminal generates an arbitrary number and compares it with a threshold based on the sequence classification information. For example, when 19 sequences are given as the bandwidth request indicator, the base station may designate 17 sequences as 5-step bandwidth request sequences and the remaining two sequences as 3-step bandwidth request sequences, which are broadcast channels. It may inform the terminal through. If a bandwidth request is required, the terminal generates a random number q and compares it with the threshold p. The terminal may select a three-step bandwidth request process or a five-step bandwidth request process according to whether q> p. For example, when the threshold p is 2/19 and 0 <q≤1, if q> p, a 5-step bandwidth request process may be performed, and if q≤p, a 3-step bandwidth request process may be performed. When the 3-step bandwidth request process is selected, the terminal transmits one of the 3-step bandwidth request sequences through the bandwidth request channel. When the 5-step bandwidth request process is selected, the terminal transmits one of the 5-step bandwidth request sequences through the bandwidth request channel.

When a terminal performing a 5-step bandwidth request process and a terminal performing a 3-step bandwidth request process through one bandwidth request channel send a bandwidth request indicator without distinguishing a sequence, the base station determines that the terminal performs the 3-step bandwidth request process. It is not known whether to perform the 5-step bandwidth request process. This problem can be solved by dividing the subset of bandwidth request indicators according to the bandwidth request process.

The bandwidth request indicator may be transmitted on a pilot tone of the bandwidth request channel. The bandwidth request message may be transmitted on a data tone of the same bandwidth request channel.

10 shows an example of a bandwidth request channel.

Referring to FIG. 10, the bandwidth request channel may include at least one bandwidth request tile. The bandwidth request channel may consist of three distributed bandwidth request tiles. That is, the bandwidth request tiles included in the bandwidth request channel may be distributed and arranged in the frequency domain or the time domain. The bandwidth request tile may consist of a plurality of OFDM symbols in the time domain and a plurality of subcarriers in the frequency domain. The bandwidth request tile may consist of six consecutive subcarriers on 6 OFDM symbols.

The bandwidth request tile may consist of a plurality of pilot tones P and a plurality of data tones (except P). The bandwidth request sequence may be mapped to the pilot tone of the bandwidth request tile, and the bandwidth request message may be mapped to the data tone. For example, the bandwidth request tile may include 19 pilot tones and 17 data tones. A bandwidth request sequence is mapped to a plurality of pilot tones, and channel estimation and user classification of a bandwidth request channel can be performed using the same.

All the above functions may be performed by a processor such as a microprocessor, a controller, a microcontroller, an application specific integrated circuit (ASIC), or the like according to software or program code coded to perform the function. The design, development and implementation of the code will be apparent to those skilled in the art based on the description of the present invention.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. You will understand. Therefore, the present invention is not limited to the above-described embodiment, and the present invention will include all embodiments within the scope of the following claims.

1 is a block diagram illustrating a wireless communication system.

2 shows an example of a frame structure.

3 illustrates a process of transmitting uplink data according to an embodiment of the present invention.

4 is a flowchart illustrating a five-step bandwidth request procedure according to an embodiment of the present invention.

5 is a flowchart illustrating a three-step bandwidth request procedure according to an embodiment of the present invention.

6 shows an example of an uplink data format used in a bandwidth request process.

7 shows another example of an uplink data format used in a bandwidth request process.

8 shows a procedure of performing a bandwidth request process for minimizing the amount of information of a bandwidth request message according to an embodiment of the present invention.

9 illustrates a method of selecting a bandwidth request process according to an embodiment of the present invention.

10 shows an example of a bandwidth request channel.

Claims (12)

In a method for performing a bandwidth request process in a wireless communication system, Transmitting a bandwidth request indicator and a bandwidth request message over a bandwidth request channel; Receiving an uplink grant message indicating an uplink radio resource in response to the bandwidth request indicator and the bandwidth request message; And And transmitting uplink data after receiving the uplink grant message, wherein the uplink grant message includes type information of the uplink grant message. The method of claim 1, wherein the type information of the uplink grant message indicates that the uplink grant message is for the case where only the bandwidth request indicator is detected. The bandwidth request according to claim 1, wherein the type information of the uplink grant message indicates an uplink grant message for the case where only the bandwidth request indicator is detected. A method for performing a bandwidth request process in a wireless communication system, further comprising the step of transmitting a message. The bandwidth request process of claim 1, wherein the type information of the uplink grant message indicates that the uplink grant message is an uplink grant message indicating an uplink radio resource for transmitting the uplink data. How to. The bandwidth request procedure of claim 1, wherein the type information of the uplink grant message indicates that the bandwidth request indicator and the uplink grant message are detected when the bandwidth request message is detected. How to. The bandwidth request in a wireless communication system according to claim 1, wherein the uplink grant message includes a cyclic redundancy check (CRC) for error detection, and type information of the uplink grant message is masked on the CRC. How to do the process. The method of claim 6, wherein the uplink grant message includes an identifier of a terminal, and the terminal's ID is masked in the CRC. The method of claim 1, wherein the bandwidth request message includes a partial ID of the terminal including a full ID of the terminal or some bits of the full ID. The method of claim 8, wherein the uplink data includes a media access control (MAC) header, an extension header, and a CRC, and whether to include the extension header is indicated in the header, and the extension header is an entire ID of the terminal or And performing a bandwidth request process, characterized in that the entire ID includes remaining portions except the partial ID. The method of claim 1, wherein the bandwidth request message includes a partial ID of the terminal, which is composed of some bits of the entire ID of the terminal, and the uplink data includes the remaining part except the partial ID in the full ID. Performing a bandwidth request process. The method of claim 1, further comprising receiving an acknowledgment signal for the bandwidth request indicator and the bandwidth request message. The bandwidth requesting channel of claim 1, wherein the bandwidth request channel includes a plurality of tiles distributed in a frequency domain, and the tiles comprise a plurality of consecutive subcarriers on a plurality of OFDM symbols. How to do the process.

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