KR101540484B1 - Method of performing bandwidth request procedure in wireless communication system - Google Patents

Abstract

A method for performing a bandwidth requesting process in a wireless communication system includes receiving a selected bandwidth request sequence in a sequence set including a plurality of sequences through a bandwidth request channel, And selecting a bandwidth request process to be performed in the process, wherein the sequence set is divided into a plurality of subsets corresponding to the general bandwidth request process and the fast bandwidth request process. The bandwidth request process can be performed more quickly and efficiently.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for performing bandwidth request in a wireless communication system,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to wireless communication, and more particularly, to a method for performing a bandwidth requesting process.

The Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard provides techniques and protocols for supporting broadband wireless access. Standardization progressed from 1999 and IEEE 802.16-2001 was approved in 2001. It is based on a single carrier physical layer called 'Wirelssman-SC'. 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'. The IEEE 802.16-2004 standard was revised in 2004 after the IEEE 802.16a standard was completed. IEEE 802.16-2004 / Cor1 was completed in 2005 in the form of 'corrigendum' to correct bugs and errors in the IEEE 802.16-2004 standard.

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

The communication between the base station and the terminal is performed by downlink (DL) transmission from the base station to the terminal and uplink (UL) transmission from the terminal to the base station. A conventional IEEE 802.16e-based system profile supports a time division duplex (TDD) scheme for dividing downlink transmission and uplink transmission into time domains. The TDD scheme is a scheme in which uplink and downlink transmission are performed at different times using the same frequency band. The TDD scheme is advantageous in that frequency selective scheduling is simple because the uplink channel characteristics and the downlink channel characteristics are reciprocal. In IEEE 802.16m, a frequency division duplex (FDD) scheme is considered as well as a TDD scheme. The FDD scheme is a scheme in which downlink transmission and uplink transmission are simultaneously performed through different frequency bands. In IEEE 802.16e, a 5-ms TDD frame is used, while in IEEE 802.16m, a 20-ms super-frame for using TDD and FDD is considered.

In IEEE 802.16e, if there is data to be transmitted in the uplink, the MS performs a bandwidth request (BW REQ) process to the BS. The bandwidth request procedure in IEEE 802.16e includes (1) transmitting a bandwidth request indicator, (2) transmitting a response message to a bandwidth request indicator, (3) transmitting a bandwidth request message, (4) transmitting a UL acknowledgment message, Link data transmission is a five step process. The bandwidth request indicator is selected as one of predetermined orthogonal codes and transmitted over the contention-based channel. If the bandwidth request indicator transmitted by the terminal does not collide with the bandwidth request indicator of another terminal, the base station transmits an UL grant message for 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 MS receiving the UL grant message transmits a bandwidth request message through a predetermined radio resource. The bandwidth request message includes a connection identifier (CID) of the UE, a size of a requested radio resource, and the like.

Upon receiving the bandwidth request message, the base station transmits an uplink grant message including the uplink radio resource size and location information for uplink data transmission to the UE 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 UE transmits uplink data through an uplink radio resource indicated by an uplink grant message for uplink data transmission. A header including a CID of the UE and a cyclic redundancy check (CRC) for error check of data are added to the UL data and transmitted.

In IEEE 802.16m, an E-MBS (Enhanced Multicast Broadcast Service) for various multimedia services, a multi-hop relay for improving services for shadow areas, a femtocell ), And the like. The macrocell, the relay base station, and the femtocell can use different frequency bands for interference mitigation. When a large number of relay base stations or femtocells are placed in a macro-cell, the inter-cell handover of the UE becomes frequent, and the UE performs the bandwidth request process more frequently. In addition, in continuously providing a high-capacity real-time service such as video communication, a delay in the bandwidth request process may cause a deterioration of the service quality.

There is a need for a more efficient method of performing the bandwidth request process in order to improve the service quality of the wireless communication system.

SUMMARY OF THE INVENTION The present invention provides a method of efficiently performing a bandwidth request process.

A method of performing a bandwidth request process in a wireless communication system according to an embodiment of the present invention includes receiving a bandwidth request sequence selected from a sequence set including a plurality of sequences through a bandwidth request channel, Selecting a bandwidth request process to be performed in a bandwidth request process and a fast bandwidth request process, wherein the sequence set is divided into a plurality of subsets corresponding to the general bandwidth request process and the fast bandwidth request process.

A method of performing a bandwidth requesting process in a wireless communication system according to another aspect of the present invention includes receiving a sequence selected from a sequence set for performing a first bandwidth request process and a sequence set for performing a second bandwidth request process Receiving an uplink grant message including uplink radio resource allocation information in response to the sequence, and transmitting data through the uplink radio resource.

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

The following description is to be understood as illustrative and non-limiting, such as 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 And can be used in various wireless communication systems. CDMA may be implemented in radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. The TDMA may be implemented in a wireless technology such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA can be implemented with wireless technologies such as IEEE 802.11 (Wi-Fi), IEEE 802.16e (WiMAX), IEEE 802-20, and E-UTRA (Evolved UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3GPP (3rd Generation Partnership Project) LTE (Long Term Evolution) is a part of E-UMTS (Evolved UMTS) using E-UTRA, adopting OFDMA in downlink and SC-FDMA in uplink. IEEE 802.16m is the evolution of IEEE 802.16e.

For clarity of description, IEEE 802.16m is mainly described, but the technical idea 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 (BS) 20. Each base station 20 provides communication services for a specific geographic area (commonly referred to as 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 be a user equipment (UE), a user terminal (UT), a subscriber station (SS), a wireless device, a personal digital assistant A wireless modem, a handheld device, and the like. The base station 20 generally refers to a fixed station that communicates with the terminal 10 and may be referred to as another term such as an evolved-NodeB (eNB), a base transceiver system (BTS), an access point have.

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

Fig. 2 shows an example of a frame structure.

Referring to FIG. 2, a superframe includes a superframe header and four frames F0, F1, F2, and F3. The size of each super frame is 20 ms, and the size of each frame is 5 ms, but the present invention is not limited thereto. The superframe header can be placed first in the superframe, and is assigned a common control channel. 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 constituting a super frame or system information.

 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 be composed of 6 or 7 OFDM symbols, but this is only an example. A TDD (Time Division Duplexing) scheme or an FDD (Frequency Division Duplexing) 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 TDD frame are divided into the uplink subframe and the downlink subframe in the time domain. In the FDD scheme, each subframe is used for uplink transmission or downlink transmission at different frequencies of the same time. That is, subframes in a frame of the FDD scheme are divided into an uplink subframe and a downlink subframe in the frequency domain. The uplink transmission and the downlink transmission occupy different frequency bands and can be performed at the same time.

The subframe includes at least one frequency partition. The frequency partition is composed of at least one physical resource unit (PRU). The frequency partition may include a Localized PRU and / or a Distributed PRU. The frequency block may be used for other purposes such as partial 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 surframe is composed of six OFDM symbols, the PRU can be defined as 18 subcarriers and 6 OFDM symbols. A Logical Resource Unit (LRU) is a basic logical unit for distributed resource allocation and localized resource allocation. The LRU is defined as a plurality of OFDM symbols and a plurality of subcarriers, and includes pilots used in the PRU. Therefore, the number of suitable subcarriers in one LRU depends on the number of allocated pilots.

A Logical Distributed Resource Unit (DRU) may be used to obtain frequency diversity gain. The DRU includes subcarrier groups distributed in one frequency band. The size of the DRU is equal to the size of the PRU. The minimum unit forming the DRU is one subcarrier.

A Logical Contiguous Resource Unit (CRU) may be used to obtain frequency selective scheduling gain. 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 requesting process is a process of requesting the UE to allocate uplink radio resources to the base station for uplink transmission. The UE can allocate uplink radio resources through a bandwidth request process and transmit uplink data.

≪ Power-on of terminal or uplink data transmission after handover >

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

3, when the UE is powered on or performs handover from a neighbor cell in a cell region of the BS, the MS receives an MS_ID for identifying the MS and a Flow ID for connecting to the specific service from the BS (S110). The Flow ID indicates an ID of a service used by a terminal to set a specific service (e.g., voice call, video call, control information transmission, etc.). Since a plurality of services can be provided for one terminal, the terminal can receive a plurality of Flow IDs. The Flow ID can indicate the periodicity of the service.

The UE performs a contention based BW REQ process (S120). The contention-based bandwidth requesting process is performed by transmitting a sequence arbitrarily selected by the UE among a predetermined orthogonal code through a bandwidth request channel (BW REQ channel) defined competitively with another UE. The bandwidth request channel includes radio resources 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 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 six OFDM symbols. The contention-based bandwidth request process includes a 3-step bandwidth request (3-step BW REQ) process and a 5-step bandwidth request (5-step BW REQ) process. The 3-step bandwidth request process is a method of transmitting uplink data more quickly by reducing the procedure of the 5-step bandwidth request process. If the 5-step bandwidth request process is a general bandwidth request process, then the 3-step bandwidth request process is a fast bandwidth request process. The procedure of 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 UE can allocate uplink radio resources and transmit initial uplink data. If the period of the service and the size of the data corresponding to the Flow ID assigned by the UE are fixed, the BS may directly allocate the uplink radio resource without requesting the bandwidth of the UE.

A terminal that has transmitted uplink data to a base station transmits subsequent uplink data using a contention-based bandwidth request process or a non-contention based BW REQ process or a polling IE (information element) (S130). The non-contention-based bandwidth request process is performed when the base station knows a sequence to be used by the terminal for bandwidth request, or when a specific radio resource is designated for bandwidth request and the terminal can perform a bandwidth request without competition with another terminal do. The polling information is information periodically provided for QoS (Quality of Service) and traffic characteristics for uplink transmission. If the uplink data to be transmitted by the terminal that transmitted the uplink data is data of the flow corresponding to the service without periodicity, the terminal performs the contention-based bandwidth request process again to transmit the uplink data. If the uplink data to be transmitted by the mobile station is data of a flow corresponding to a periodic service, or the size of the data changes, the base station assigns a radio resource for requesting non-contention-based bandwidth to the mobile station or transmits a bandwidth request header using polling information . Real-time services such as streaming service or real time polling service (rtPS) and extended real time polling service (ertPS) are examples of services having periodicity or varying size of data.

In this manner, since the terminal can perform the bandwidth request using the contention-based bandwidth request or the polling information without performing the contention-based bandwidth request process on the uplink data to be transmitted later, the bandwidth request A delay due to failure can be prevented. In the non-contention based bandwidth request process, a separate radio resource must be allocated to the UE, which may result in overhead. A 3-step bandwidth request process may be performed to reduce the overhead that may occur in the contention-based bandwidth request process and reduce the delay of the bandwidth request process.

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

<Procedure of 5 step bandwidth request process>

FIG. 4 shows a procedure of a 5-step bandwidth requesting process according to an embodiment of the present invention.

Referring to FIG. 4, the terminal sends a bandwidth request indicator to the base station (S210). The bandwidth request indicator may be selected from any one of a predetermined set of orthogonal or semi-orthogonal codes. The type, length, etc., of the orthogonal or quasi-orthogonal code used as the bandwidth request indicator is 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 depending on the cell or sector have. The terminal may transmit a first bandwidth request message including information necessary for bandwidth allocation together with a bandwidth request indicator. The information required for bandwidth allocation includes MS_ID, Flow ID, and scheduling type. The first bandwidth request message transmitted together with the bandwidth request indicator in the 5-step bandwidth request process may include some of the 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 may include some MS_ID. Some MS_IDs may be composed of a least significant bit (LSB) or a most significant bit (MSB) in the entire MS_ID, with some bits omitted. The bandwidth request indicator may be transmitted over a contention-based bandwidth request channel. The first bandwidth request message may be a message of a media access control (MAC) layer, which is an upper layer of the physical layer.

The base station can correlate the entire orthogonal or quasi-orthogonal code set with the bandwidth request indicator received from the terminal to find the sequence selected by the terminal based on the 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. If CRC is included in the first bandwidth request message, whether the first bandwidth request message is erroneous or not is determined through CRC. If the CRC is not included in the first bandwidth request message, the first bandwidth request message may be erroneously determined through Received Signal Strength Indication (RSSI) or Carrier to Interference Ratio (CINR).

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

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

The base station transmits an 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 referred to as a control grant message. The control authorization message may include information as shown in Table 3.

Information note UL grant type  UL grant when only the bandwidth request indicator is detected. confirm BW REQ indicator  The sequence index of the received BW REQ indicator, the region information resource for BW REQ message  BW REQ header region or non-contention-based BW REQ region CRC or Broadcast MS_ID  MS_ID or UL grant type masking

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

The type information of the uplink grant message is information for distinguishing types of grant messages 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 for the case where only the bandwidth request indicator is detected. The type information of the UL grant message may be transmitted through a separate resource region or may be masked on the CRC and transmitted. For example, if the MS_ID of 12 bits is masked in the 16-bit CRC, the type information of the UL grant message may be masked and transmitted in the remaining 4 bits.

The confirmation information for the bandwidth request indicator indicates a sequence index, a resource region, and the like of the bandwidth request indicator received by the base station. An orthogonal or quasi-orthogonal code set used as a bandwidth request indicator may be distinguished for various purposes, and a bandwidth request indicator may indicate additional information about the use of the orthogonal or quasi-orthogonal code set. For example, if the orthogonal or quasi-orthogonal code set of the bandwidth request indicator is used separately according to the 5-step bandwidth request process and the 3-step bandwidth request process, the confirmation information for the bandwidth request indicator is used as a threshold value Value indicating whether the 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 may indicate a resource region for transmitting a header of a bandwidth request message to be transmitted by the mobile station in the future, or may transmit a contention-based bandwidth request message in a contention- Can represent the resource area for the &lt; RTI ID = 0.0 &gt;

The CRC is for detecting an error in the control grant message, and the CRC can be masked with the MS_ID or the type information of the UL grant message. The MS does not transmit the first bandwidth request message or an error occurs in the first bandwidth request message and the MS can not know the MS_ID of the MS. 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 arbitrarily given to the MS in order to perform a subsequent bandwidth request process. If the broadcast MS_ID is not masked in the CRC or the bits of the broadcast MS_ID are smaller than the bits of the CRC, the type information of the UL grant message included in the control acknowledgment message may be masked in the CRC.

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

The base station can send an ACK signal for the second bandwidth request message (S250). The ACK signal may be transmitted or omitted in 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, the acknowledgment message for data may include information as shown in Table 4.

Information note UL grant type  UL grant for UL data transmission confirm BW REQ message  Confirmation of the received BW REQ message and the requesting radio resource resource for UL data  UL radio resource location and size 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 uplink grant message, (2) acknowledgment information of bandwidth request message, (3) uplink radio resource allocation information for 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 UL grant message may be transmitted through a separate resource region or may be masked on the CRC and transmitted. The confirmation information of the bandwidth request message indicates whether to confirm the MS_ID, the flow ID, the size of the requested radio resource, the scheduling type, etc. included in the bandwidth request message received by the base station. The uplink radio resource allocation information for the uplink data indicates the location and size of the uplink radio resource allocated to the mobile station by reflecting the size of the radio resource requested by the mobile station. The CRC is used to detect whether or not an acknowledgment message for data is erroneous, and the CRC can be masked with the type information of the entire MS_ID or uplink grant message. 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 MS transmits the uplink data through the uplink radio resource allocated through the grant message for data (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 need not be transmitted separately.

Even if the terminal sends only the bandwidth request indicator, the 3-step bandwidth request process can be performed in the following cases.

(1) The terminal arbitrarily performs the 3-step bandwidth request process. When the BS transmits an uplink grant message for the second bandwidth request message, the UE may arbitrarily transmit the uplink data instead of the second bandwidth request message. At this time, the base station can determine whether it is the second bandwidth request message or the uplink data by looking at the header type of the data transmitted by the terminal. Accordingly, steps S240 to S260 are omitted, and a three-step bandwidth request process can be performed.

(2) the base station arbitrarily performs the 3-step bandwidth request process. The base station may arbitrarily transmit an acknowledgment message for data instead of transmitting the uplink grant message (control grant message) for the second bandwidth request message. The UE can determine whether the grant message is a control grant message or a data grant message through the type information of the UL grant message. Therefore, the steps S230 to S250 are omitted, and a three-step bandwidth request process can be performed.

&Lt; Procedure of 3 step bandwidth request process >

FIG. 5 illustrates a procedure for performing a 3-step bandwidth request process according to an embodiment of the present invention.

Referring to FIG. 5, the MS sends a bandwidth request indicator and a bandwidth request message to the BS (S310). The bandwidth request indicator and the bandwidth request message may be transmitted over the contention-based bandwidth request channel. The bandwidth request indicator may be selected from any one of a predetermined set of orthogonal or quasi-orthogonal codes. Since transmitting a lot of information through a contention-based bandwidth request channel may cause waste of radio resources, the bandwidth request message should include minimum information required 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 requested radio resource, a received power level, and the like. The OoS ID is a QoS index composed of the scheduling type and priority of the bandwidth request. The bandwidth request message may include the full 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 a form in which some bits are omitted from the LSB or MSB in the entire MS_ID.

The base station can correlate the entire orthogonal or quasi-orthogonal code set with 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 can estimate and demodulate the channel for the bandwidth request message using the bandwidth request indicator. If CRC is included in the bandwidth request message, it is determined whether the bandwidth request message is an error through the CRC. If the CRC is not included in the bandwidth request message, it may be determined whether the bandwidth request message is erroneous through RSSI or CINR. If the bandwidth request message is received without error, the base station performs a three-step bandwidth request procedure.

The base station can 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 in a predetermined period.

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

Information note UL grant type  UL grant when both bandwidth request indicator and message are detected. confirm BW REQ indicator and message  The sequence index, MS_ID, and region information of the received BW REQ indicator resource for UL data  UL radio resource location and size for UL data transmission CRC or Broadcast MS_ID  MS_ID or UL grant type masking

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

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

The acknowledgment information for the bandwidth request indicator and the bandwidth request message includes 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 requested radio resource, the type of scheduling, Indicating the resource area (e.g., the bandwidth request indicator and the frame number to which the message was sent).

The uplink radio resource allocation information for the uplink data indicates the location and size of the uplink radio resource allocated to the mobile station by reflecting the size of the radio resource requested by the mobile station.

The CRC is for detecting whether an acknowledgment message for data is erroneous, and the CRC may be masked with the MS_ID or the type information of the UL acknowledgment message. If the base station knows the total MS_ID, the entire MS_ID can be masked to the CRC. If the base station knows only some MS_IDs, then only some MS_IDs may be masked to the CRC, or the remaining portion of some MS_IDs along with some MS_IDs may be masked to the CRC with a predetermined value (e.g., 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 3-step bandwidth request may be masked to the CRC.

The MS transmits the uplink data through the uplink radio resource allocated through the grant message for data (S340). When the UE receives the uplink grant message and the frame number and sequence index of the bandwidth request message transmitted by the UE match, the UE transmits the uplink data through the radio resource indicated by the base station. In the case where the MS includes the entire MS_ID in the bandwidth request message, the MS does not need to include the MS_ID in the uplink data. However, if the MS transmits only a part of MS_ID in the bandwidth request message, the MS must inform the MS of the MS_ID. When performing the 3-step bandwidth request process using some MS_IDs, a collision with another MS may occur because the MS_IDs are different but some MS_IDs are the same. For example, it can be classified if the flow ID included in the bandwidth request message is different from the scheduling type, or if the transmission frame number or the sequence index is different. However, if all the information are identical and only MSs with different MS_IDs exist, the BS can not decode the bandwidth request message, and the MS must retry the 3-step bandwidth request process or the 5-step bandwidth request process. Thus, a delay in the bandwidth request process may occur.

In order to prevent this, the MS may add an extended header including the entire MS_ID or the remaining MS_ID except for some MS_ID to the uplink data to inform the BS of the MS_ID. That is, the format of the uplink data may be changed depending on whether the bandwidth request message includes the entire MS_ID in the bandwidth request process. In addition, the format of the uplink data may be changed depending on whether the base station recognizes the MS_ID (Station ID) of the terminal to which the uplink bandwidth is to be allocated.

&Lt; Format of uplink data in the bandwidth request process >

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

Referring to FIG. 6, in the 5-step bandwidth request process or the 3-step bandwidth request process, if the bandwidth request message includes the entire MS_ID and is transmitted, the BS can know the MS_ID of the MS. Therefore, when the BS allocates the MS_ID of the MS to be allocated with the uplink resource to the MS, it is not necessary to inform the MS of the MS_ID separately at the time of uplink data transmission. The MS transmits a generic MAC header and a CRC to the uplink data.

The generic MAC header is used for general data transmission. The general MAC header includes a plurality of fields and can be used for downlink transmission as well as uplink transmission. The fields included in the general MAC header include an HT (Header Type), an EH (Extended Header Presence Indicator), a Flow ID, an EKS (Encryption Key Sequence), a Length, and the like. HT indicates the type of header. The EH indicates whether or not an extended header follows the generic MAC header. Flow ID indicates the address of the flow, EKS indicates the encryption sequence, and Length indicates the length of the payload. The number in parentheses in each field indicates the number of bits in each field. The number of bits in each field is not limited.

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

Referring to FIG. 7, if the bandwidth request message includes a part of the MS_ID or is not included in the bandwidth request message, the MS can not know the MS_ID of the MS. Also, even if only the bandwidth request indicator is transmitted in the 5th layer bandwidth request, the BS can not know the MS_ID of the MS. Therefore, the MS must inform the BS of the MS_ID at the time of uplink data transmission. The UE transmits a normal MAC header, an extended header, and a CRC to the uplink data.

Whether the extension header is included is indicated by the EH field of the generic MAC header. The extension header includes fields such as Last, Type, and Body Content. Last indicates whether the extension header is the last extension header. The uplink data may include a plurality of extension headers, and the Last field may not be assigned to the last extension header, indicating that it is the last extension header. Type indicates the type of extension header, and Body Content contains various information according to Type. The length of the Body Content can be varied according to the information included.

When the entire MS_ID is included in the uplink data, the entire MS_ID may be included in the Body Content field of the extended header. Alternatively, if the uplink data includes the remaining portion excluding the MS_ID from the entire MS_ID, the remaining MS_ID may be included in the Body Content field of the extended header. The type of the MS_ID contained in the Body Content field may be indicated according to the type of the Type field. When the uplink data is transmitted and the additional uplink radio resource is required, the MS may transmit the MS_ID together with the required bandwidth size in the extended header. The size of the required bandwidth can also be included in the Body Content field and can be dictated by the type of the Type field.

In the third-stage bandwidth request process, not all MSs transmit MS_ID through a contention-based bandwidth request channel, only MSs that transmit some MS_IDs through a contention-based bandwidth request channel and only those MSs that are allocated uplink radio resources transmit uplink It may be more efficient to transmit the full or remaining MS_ID to the data.

&Lt; Procedure of bandwidth request process considering reliability of bandwidth request indicator >

A terminal that is initially connected or handed over or a terminal that has been in an idle state for a long time does not know the SINR (Signal to Interference plus Noise Ratio) precisely because of power control inaccuracy, The threshold value 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. Particularly, in the 3-step bandwidth request process in which a channel for a bandwidth request message is estimated and demodulated using the detected bandwidth request indicator, a serious performance degradation may be caused. In order to prevent the performance degradation of the bandwidth request process, the amount of information included in the bandwidth request message transmitted together with the bandwidth request indicator should be minimized.

FIG. 8 shows a procedure of 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 a base station (S410). The bandwidth request message contains a minimum amount of information in order to ensure reliability of the estimated performance for the bandwidth request indicator. For example, the bandwidth request message may include at least one of a QoS ID or a buffer size and a CRC. The OoS ID is a QoS index composed of the scheduling type and priority of the bandwidth request. The buffer size indicates the size of the radio resource requested by the UE. That is, the MS_ID and the Flow ID of the MS are not included in the bandwidth request message. Therefore, the BS performs the bandwidth request process without knowing the terminal requesting the bandwidth.

The base station can 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 in a predetermined period.

Since the BS can not know which sequence the BS used to transmit the bandwidth request indicator, the BS performs CRC check on all orthogonal or quasi-orthogonal codes used as the bandwidth request indicator.

If a CRC error is not detected for a specific orthogonal or quasi-orthogonal code, the orthogonal or quasi-orthogonal code and the time at which the bandwidth request indicator is transmitted together with the information of the received bandwidth request message (QoS ID or buffer size) An approval message is transmitted (S430). The time point at which the bandwidth request indicator is transmitted may be represented 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 an arbitrary point in time or may be transmitted at a fixed point in time. (1) When an uplink grant message is transmitted at an arbitrary point in time, the uplink grant message includes a frame number, a slot, a transmission opportunity opportunity, a subframe number, and a bandwidth request channel index. (2) When the uplink grant message is transmitted at a fixed time, the UE can know the time at which the uplink grant message is transmitted if it knows only information such as a transmission opportunity or a bandwidth request channel index.

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

On the other hand, a CRC error for the bandwidth request message is not detected, but the base station can send an ACK signal when there is no radio resource to allocate immediately. Since the BS can not know which terminal requests the bandwidth, the BS broadcasts the corresponding sequence and bandwidth request message through a separate channel, or (2) transmits a UL grant message to a predetermined value (e.g., 00. 0), or (3) an indicator for the ACK signal in the uplink grant message (for example, if data is 0, data transmission is performed after a predetermined time, and 1 is transmitted immediately).

As described above, the reliability of the bandwidth request indicator and the bandwidth request message can be improved by performing the bandwidth request process in a state where the base station does not know the terminal requesting the bandwidth. Since only a minimum amount of information is included in the bandwidth request message, it is possible to reduce the decoding burden of the bandwidth request message and reduce the execution period of the bandwidth request process. If a plurality of terminals transmit a bandwidth request message including the same information at the same time, a collision may occur between the terminals. However, if the QoS index or the buffer size included in the sequence index and bandwidth request message used as the bandwidth request indicator are the same Hardly occurs. Therefore, it is possible to perform a bandwidth request process more accurately and more accurately than the performance degradation due to the reliability problem of the detection of the bandwidth request indicator or the collision problem of the bandwidth request indicator due to the failure of the terminal to estimate an appropriate threshold value for correlation of the bandwidth request indicator have. Also, even if there are two or more terminals using the same bandwidth request indicator, if there are any terminals that have successfully CRC checked, a normal three-step bandwidth requesting process can be performed. When an error occurs in the CRC check for the bandwidth request message, the base station may perform the 5-step bandwidth request process through the bandwidth request indicator detection method using the threshold value.

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

<Selection method of bandwidth request process>

As described above, the 3-step bandwidth request process is for performing a faster bandwidth request, and the 5-step bandwidth request process is for more stably performing the contention-based bandwidth request process. A subject that determines which bandwidth request procedure to perform may be a base station or a terminal.

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

Referring to FIG. 9, in step S510, the MS sends a bandwidth request message to the BS together with a bandwidth request indicator or a bandwidth request indicator to request a bandwidth. In the 3-step bandwidth request process, the UE sends a bandwidth request indicator and a bandwidth request message. In the 5-step bandwidth request process, the MS sends only a bandwidth request indicator or a bandwidth request message together with a bandwidth request indicator.

The base station may perform the 3-step bandwidth request process or the 5-step bandwidth request process through the bandwidth request indicator or the bandwidth request message received from the terminal in operation S520. A terminal can select a desired bandwidth requesting process in a process of transmitting a bandwidth request indicator or a bandwidth request message, and the base station can select a bandwidth request process to be performed in the process of receiving a bandwidth request indicator or a bandwidth request message.

Table 6 shows examples of criteria by which a base station or a terminal selects a bandwidth request procedure.

A selection body Selection Criteria Bandwidth request process Base station The reception status of the bandwidth request indicator and message Step 3: Receive only bandwidth request indicator and message reception or bandwidth request indicator
Step 5: Receive only the bandwidth request indicator Terminal Whether to send a bandwidth request message Step 3: Send bandwidth request indicator and message transfer or bandwidth request indicator only
Step 5: Send bandwidth request indicator only Subsetting of bandwidth request indicators Separate by service type
Step 3: Send sequence for real-time service
Step 5: Send sequence for non-real-time service At random choice
Step 3: Send the sequence for the 3-step bandwidth request
Step 5: Send the sequence for the 5-step bandwidth request

When the bandwidth request message is transmitted together with the bandwidth request indicator, the base station can determine the bandwidth request process by checking the reception status of the bandwidth request indicator and the bandwidth request message. When a bandwidth request message is received together with the bandwidth request indicator, a three-step bandwidth request process is performed. In the case where only the bandwidth request indicator is received, for example, when the terminal transmits only the bandwidth request indicator, or if the base station can detect only the bandwidth request indicator due to an error in the bandwidth request message, do. Alternatively, the base station or the terminal may arbitrarily select a three-step bandwidth requesting process. Of course, if the base station can not receive both the bandwidth request indicator and the bandwidth request message, the bandwidth request procedure is unsuccessful and the terminal retries the bandwidth request procedure.

When the terminal desires to perform the 3-step bandwidth requesting process, it transmits only the bandwidth request indicator, and when it desires to perform the 5-step bandwidth requesting process, it can determine the bandwidth requesting process by transmitting a bandwidth requesting message together with the bandwidth requesting indicator.

An orthogonal or quasi-orthogonal code is used as the sequence of the bandwidth request indicator. Accordingly, the bandwidth request indicator can be transmitted in a code division multiplexing (CDM) manner to the bandwidth request channel, and the sequence of the bandwidth request indicator can be easily distinguished. The code set used as the bandwidth request indicator may be subdivided into a subset for determining the bandwidth request process.

The subset of bandwidth request indicators may be distinguished according to the type of service. For example, the types of services are largely 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 may be separated into a sequence for a real-time service and a sequence for a non-real-time service. Real-time services are sensitive to delays and non-real-time services are relatively insensitive to delays. For delay sensitive services, a faster bandwidth request process needs to be performed. Accordingly, the UE can select and send a sequence for a real-time service when its service is delay-sensitive, and select and send a sequence for a non-real-time service when it is not delay-sensitive. That is, the terminal can select and send a subset of bandwidth request indicators according to its service type. When a sequence for non-real-time service is transmitted from the mobile station, the base station can perform the 5-step bandwidth request process. When a sequence for a real-time service is transmitted from a mobile station, the base station can perform a 3-step bandwidth request process. When a certain size of data packet such as VoIP is used, the base station can perform a 3-step bandwidth request process by allocating a predefined radio resource of a predetermined size.

The subset of bandwidth request indicators can be divided into a sequence for a three-phase bandwidth request and a sequence for a five-phase bandwidth request. The sequence information for the 3-step bandwidth request and the sequence information for the 5-step bandwidth request or the index information of the separated sequence can be broadcasted. The terminal generates an arbitrary number and compares it with a threshold value based on the sequence discrimination information. For example, given 19 sequences as a bandwidth request indicator, the base station may define 17 sequences as a sequence for a 5-step bandwidth request and the remaining 2 sequences as a sequence for a 3-step bandwidth request, To the terminal. If a bandwidth request is required, the terminal generates an arbitrary number q and compares it with a threshold value p. The terminal may select either a 3-step bandwidth request process or a 5-step bandwidth request process depending on whether q> p. For example, if the threshold value p is 2/19 and 0 < q &lt; = 1, then if q &gt; p, then a 5 step bandwidth request procedure is performed, and if q p, a 3 stage bandwidth request procedure may be performed. When the 3-step bandwidth requesting process is selected, the UE transmits one of the 3-step bandwidth requesting sequences through the bandwidth request channel. When the 5-step bandwidth requesting process is selected, the UE transmits one of the 5-step bandwidth requesting sequences through the bandwidth request channel.

When a terminal performing a 5-stage bandwidth requesting process and a terminal performing a 3-stage bandwidth requesting process transmit a bandwidth request indicator through a bandwidth request channel without distinguishing between sequences, the base station determines which terminal requests a 3-step bandwidth request I do not know whether to perform the 5 step bandwidth request process. This problem can be solved by distinguishing a subset of bandwidth request indicators according to the bandwidth request procedure.

The bandwidth request indicator may be carried on the pilot tone of the bandwidth request channel. The bandwidth request message may be carried 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 be composed of three distributed bandwidth request tiles. That is, the bandwidth request tiles included in the bandwidth request channel may be distributed in the frequency domain or the time domain. The bandwidth request tile may be composed 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 six OFDM symbols.

The bandwidth request tile may be composed of a plurality of pilot tones P and a plurality of data tones (other than P). A bandwidth request sequence may be mapped to a pilot tone of a bandwidth request tile and a bandwidth request message may be mapped to a 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 sequence.

All of the functions described above may be performed by a processor such as a microprocessor, a controller, a microcontroller, an application specific integrated circuit (ASIC), etc. according to software or program code or the like coded to perform the function. The design, development and implementation of the above 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, it is intended that the present invention covers all embodiments falling within the scope of the following claims, rather than being limited to the above-described embodiments.

1 is a block diagram illustrating a wireless communication system.

Fig. 2 shows an example of a frame structure.

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

FIG. 4 shows a procedure of a 5-step bandwidth requesting process according to an embodiment of the present invention.

FIG. 5 illustrates a procedure for performing a 3-step bandwidth request process according to an embodiment of the present invention.

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

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

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

9 shows 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 (10)

A method for performing a bandwidth request procedure in a wireless communication system, Receiving a bandwidth request indicator through a pilot tone of a bandwidth request channel; And Selecting a bandwidth request process to be performed in a general bandwidth request process and a fast bandwidth request process, Wherein the plurality of subsets of the bandwidth request indicator are divided into at least one sequence for the general bandwidth request procedure and at least one sequence for the fast bandwidth request procedure, Wherein the bandwidth request process comprises comparing at least one sequence for the general bandwidth request process and at least one sequence for the fast bandwidth request process after comparing the randomly selected number with a threshold for distinguishing a plurality of subsets of the bandwidth request indicator The method comprising the steps of: receiving a request for a bandwidth request in a wireless communication system; 2. The method of claim 1, wherein a plurality of subsets of the bandwidth request indicator are distinguished according to a type of service to be performed. 2. The method of claim 1, wherein the plurality of subsets of the bandwidth request indicator are divided into at least one sequence for a real-time service and at least one sequence for a non-real-time service. Way. delete The method of claim 1, wherein a plurality of subsets of the bandwidth request indicator are multiplexed and transmitted through the bandwidth request channel. The method of claim 1, wherein a bandwidth request message including information necessary for bandwidth allocation is transmitted together with the bandwidth request indicator. delete delete delete delete

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