KR20120048433A - Apparatus and method for transmitting a scheduling request in wireless communication system - Google Patents

Abstract

PURPOSE: A method for transmitting a scheduling request signal in a mobile communication system is provided to reduce delay of SR transmission in order to sequentially transmit backward data and scheduling request in a mobile communication system. CONSTITUTION: A transmission resource for backward transmission is available for TTI(Traffic and Travel Information). A PUCCH(Physical Uplink Control Channel) resource for SR(Scheduling Request) transmission is set up as the TTI. The terminal inspects whether an SR-prohibit timer is operated(530,535). The terminal directs in order to transmit the SR by using the PUCCH resource(545).

Description

Method and apparatus for transmitting scheduling request signal in mobile communication system {APPARATUS AND METHOD FOR TRANSMITTING A SCHEDULING REQUEST IN WIRELESS COMMUNICATION SYSTEM}

The present invention relates to a scheduling request of a terminal in a mobile communication system. More particularly, the present invention relates to a method and apparatus for transmitting a scheduling request signal by a terminal in a mobile communication system.

In general, a mobile communication system has been developed for the purpose of providing communication while securing user mobility. Such a mobile communication system has reached a stage capable of providing high-speed data communication service as well as voice communication due to the rapid development of technology.

Recently, the standard work on Long Term Evolution (LTE) has been completed in 3GPP as one of the next generation mobile communication systems, and the standard work on LTE-A (Advanced) is in progress.

Meanwhile, unlike a voice service, a data service determines an amount of resources allocated to one terminal according to an amount of data to be transmitted and a channel condition. Therefore, in a wireless communication system such as a mobile communication system, management such as allocating transmission resources is performed in consideration of the amount of resources to be transmitted by the scheduler, the situation of the channel, and the amount of data. The same is true in LTE, and a scheduler located in a base station manages and allocates radio transmission resources.

In a wireless communication system such as a mobile communication system, it is classified into forward transmission and reverse transmission according to a data transmission direction. The forward direction means the direction from the base station to the terminal, and the reverse direction means the direction from the terminal to the base station. In the forward direction, the base station can accurately determine the amount of data to be transmitted. Therefore, the scheduler can perform the scheduling smoothly because the channel condition, the amount of resources, and the amount of data to be transmitted can be accurately identified. However, the assignment of the uplink radio transmission resource is difficult in the uplink transmission in that the scheduler may be performed in a state in which the scheduler does not accurately identify the buffer status of the terminal.

In the LTE system, the UE reports the buffer status to the base station using the buffer status report control element. The buffer status report control information is set to be transmitted when a specific condition is satisfied. For example, the case of newly generating high-priority data or when a predetermined timer expires.

The Buffer Status Report (BSR) generated due to the occurrence of high priority data is called a normal BSR. The UE requests scheduling when a regular BSR occurs in order to report the buffer status to the base station as soon as possible. : 1-bit information called SR) is transmitted to the base station to request a transmission resource for BSR transmission.

The present invention provides a method and apparatus for a terminal to quickly transmit a scheduling request to a base station in a mobile communication system.

The present invention provides a method and apparatus for a terminal to simultaneously transmit a scheduling request and reverse data transmission to a base station in a mobile communication system.

In the wireless communication system provided by the present invention, a scheduling request method of a terminal may include: when a scheduling request transmission time and the reverse data transmission time point are the same, and when control information except for the scheduling request is not transmitted at the transmission time point, Transmitting the scheduling request.

Representative effects of the configuration of the present invention are as follows.

According to the present invention, even when the scheduling request time and the reverse data transmission time are set to be the same, the system may improve performance by reducing the delay incurred during SR transmission to simultaneously perform the scheduling request transmission and the reverse data transmission.

1 is a diagram illustrating the structure of an LTE mobile communication system;
2 is a diagram illustrating a wireless protocol of LTE,
3 is a diagram illustrating BSR and SR transmission in an LTE system;
4 is a view for explaining an operation according to an embodiment of the present invention;
5 is a view for explaining a first operation of a terminal according to the present invention;
6 is a view showing another terminal operation of the present invention;
6 is a view for explaining a second operation of a terminal according to the present invention;
7 is a diagram illustrating a configuration of a terminal device according to the present invention.
7 is a diagram illustrating a terminal device.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is to be noted that the same elements among the drawings are denoted by the same reference numerals whenever possible. Also, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

Prior to the detailed description of the present invention, the basic concepts of the present invention will be briefly described.

In the present invention, it is determined whether a time point at which a terminal can transmit a scheduling request (SR) through a reverse control channel (PUCCH) and a time point at which a reverse data can be transmitted through a reverse common channel (PUSCH) is overlapped. This may be determined whether resources for scheduling request and resources for reverse data transmission are set at this time. As a result of the determination, if overlapping, it is checked whether a predetermined SR transmission condition is met, and if the SR transmission condition is satisfied, the SR is transmitted at the transmission time.

In the present invention, the predetermined SR condition is (1) the terminal is configured to allow simultaneous transmission of control information and reverse data information, and (2) other control information, for example, HARQ feedback or CQI information, etc. (3) This case refers to a case in which the corresponding time point belongs to a time section other than a data transmission prohibition section or a time section in which the SR transmission is prohibited. However, the condition (3) is not an essential condition and may be a condition added to the conditions (1) and (2).

Hereinafter, the present invention will be described with reference to the LTE communication system for convenience of description. However, this is merely for convenience of description and the present invention may be applied to a similar communication system.

Before describing the present invention in detail, the LTE mobile communication system will be described in more detail with reference to FIGS. 1, 2, and 3.

1 is a diagram illustrating the structure of an LTE mobile communication system.

Referring to FIG. 1, a radio access network of an LTE mobile communication system includes a next-generation base station (hereinafter referred to as an Evolved Node B, ENB or Node B) 105, 110, 115, and 120, and a mobility management entity (MME) 125. It consists of a Serving-Gateway (S-GW) 130. The user equipment (hereinafter referred to as UE) 135 connects to an external network through the ENB 105 and the S-GW 130.

The ENBs 105 to 120 correspond to the Node Bs in the existing Universal Mobile Telecommunications System (UMTS) system. The ENB is connected to the UE 135 by a radio channel and performs a more complicated role than the existing Node B.

In LTE, all user traffic, including real-time services such as Voice over IP (VoIP) over the Internet protocol, is serviced through a shared channel, which requires a device for collecting and scheduling UE's context information. 105-120). One ENB typically controls multiple cells. In order to realize a transmission rate of up to 100 Mbps, LTE uses Orthogonal Frequency Division Multiplexing (OFDM) as a radio access technology in a bandwidth of up to 20 MHz. In addition, an adaptive modulation < RTI ID = 0.0 > coding < / RTI > method (hereinafter referred to as AMC) which determines a modulation scheme and a channel coding rate according to the channel state of the terminal is applied. S-GW is a device that provides a data bearer, and generates or removes a data bearer under the control of the MME. The MME 125 is a device in charge of various control functions and is connected to a plurality of ENBs 105 to 120.

2 is a diagram illustrating a radio protocol of LTE.

Referring to FIG. 2, a wireless protocol of an LTE system includes packet data convergence protocols 205 and 240 (PDCP), radio link control 210 and 235 (RMC), and medium access control 215 and 230 (MAC). The PDCP (Packet Data Convergence Protocol) 205, 240 is responsible for operations such as IP header compression / restore, and the radio link control (hereinafter referred to as RLC) 210, 235 is a PDCP PDU (Packet Data Unit). ) Is reconfigured to an appropriate size to perform ARQ operations. The MACs 215 and 230 are connected to several RLC layer devices configured in one terminal, and multiplex RLC PDUs to MAC PDUs and demultiplex RLC PDUs from MAC PDUs. The physical layers 220 and 225 channel-code and modulate upper layer data, make an OFDM symbol, and transmit it to a wireless channel, or demodulate, channel decode, and transmit an OFDM symbol received through a wireless channel to a higher layer. The data input to the protocol entity based on the transmission is called a service data unit (SDU), and the output data is called a protocol data unit (PDU).

3 is a diagram illustrating BSR and SR transmission in an LTE system.

The base station 310 may set an SR transmission resource to the terminal 305. The SR transmission resource is a resource for transmitting an SR signal requesting a transmission resource for BSR transmission to the base station, and may be set to be available every predetermined period. The SR transmission resource is set in a reverse control channel called a PUCCH (Physical Uplink Control Channel).

In step 315, when the base station 310 transmits a control message including SR transmission resource configuration information to the terminal 305, the terminal 305 receives the control message and its SR transmission resource is set to a certain transmission resource. It can be seen that it is available in the subframe.

Subsequently, if the normal BSR is triggered in step 320, the SR transmission process is also triggered in step 325. The SR transmission process means transmission of an SR until a transmission resource for BSR transmission is allocated. That is, when the SR transmission process is triggered, the terminal 305 repeatedly performs SR transmission until the SR transmission process is cancelled. Accordingly, in step 335 and 340, the UE 305 transmits an SR when the SR frame has available subframes. If it is assumed that the terminal 305 has been allocated the uplink transmission resource for transmitting the BSR in step 345, and transmits the BSR through the allocated uplink transmission resource in step 350. When the BSR is transmitted in this way, the triggered SR transmission process is canceled. That is, the SR transmission is stopped.

However, as in steps 330 to 340, there may be a case in which a time point for SR transmission is the same as a time point for reverse data transmission through PUSCH (hereinafter, referred to as “PUSCH transmission”). In this case, in the conventional LTE system, the UE abandons SR transmission at the present time and delays SR transmission until the next SR transmission time. This is because the current LTE REL-8 communication system is designed based on single carrier reverse transmission. That is, the current LTE REL-8 communication system uses a multicarrier-based Orthogonal Frequency Division Multiple Access (OFDMA) scheme for forward transmission, but uses a Single Carrier Frequency Division Multiple Access (SC-FDMA) scheme for reverse transmission. Doing. Accordingly, a single carrier based LTE REL-8 based terminal cannot simultaneously perform SR transmission and PUSCH transmission in the same subframe. In this case, the UE gives up SR transmission and performs PUSCH transmission.

However, the LTE REL-10 communication system, which is currently undergoing standardization, uses a multi-carrier method even for reverse transmission. Therefore, if the terminal supports the LTE REL-10 communication system, it is possible to transmit the SR and PUSCH in the same subframe. Therefore, in the present invention, when the SR transmission point and the PUSCH transmission point overlap, the UE first checks whether the PUSCH transmission and the SR transmission can be transmitted at the same time, and then, if the predetermined condition is met, the SR transmission and the PUSCH transmission are simultaneously performed. The present invention proposes a method and apparatus for delaying SR transmission to a next time point if it does not correspond to the predetermined condition. Meanwhile, hereinafter, the “time” in the SR transmission “time” or the PUSCH transmission “time” may mean the same subframe or transmission time interval in the LTE system. However, since the subframe or the transmission time interval is based on the LTE system, the determination criteria for the same time point of the present invention may be different in other communication systems.

 4 is a diagram illustrating an operation according to an embodiment of the present invention.

As described above, the present invention is based on a multicarrier-based uplink transmission scheme. Therefore, it is assumed that the terminal 405 can simultaneously transmit user data and control information. In the LTE system, the user data is transmitted through a physical layer reverse shared channel (PUSCH), and the control information is transmitted through a physical layer reverse control channel (PUCCH). The control information may include not only the SR, but also HARQ feedback information and a channel quality indicator (CQI) transmitted by the terminal to the base station. Meanwhile, hereinafter, transmission of the user data may be referred to as "PUSCH transmission" and transmission of the control information may be referred to as "PUCCH transmission".

Referring to FIG. 4, in step 415, the base station 410 transmits a carrier set through a predetermined RRC control message, that is, an RRC connection reconfiguration message, to a terminal 405 capable of simultaneously performing PUSCH transmission and PUCCH transmission. Configure functions supported by REL-10 system such as carrier aggregation). Meanwhile, the RRC control message may include information indicating whether to simultaneously transmit the PUCCH and the PUSCH and the SR transmission resource information to the UE.

Whether simultaneous transmission of PUSCH and PUCCH is possible is primarily determined by the inherent performance of the terminal 405, and the base station finally determines whether simultaneous transmission is possible. For example, the terminal 405 reports whether the PUSCH and the PUCCH can be simultaneously transmitted to the base station through an initial call setup process, and the base station 410 reports that the simultaneous transmission of the PUSCH and the PUCCH is possible. In consideration of this, it is determined whether to allow simultaneous PUSCH and PUCCH transmission. For example, even in a terminal capable of simultaneously transmitting PUSCH and PUCCH, disabling simultaneous transmission may be advantageous in scheduling when the current channel state is poor.

Meanwhile, as described above, the PUCCH transmission includes HARQ feedback transmission, channel quality indicator (CQI) transmission, SR transmission, and the like. In the current LTE REL-8 system, when HARQ feedback or CQI is to be transmitted simultaneously with a PUSCH, a part of the PUSCH is punctured and a HARQ feedback or CQI is transmitted together with the PUSCH.

However, in the existing LTE REL-8 system, a scheme for simultaneously performing SR transmission and PUSCH transmission has not been considered. As described above, the UEs supporting the carrier aggregation function of the LTE REL-10 can transmit multiple uplinks, thereby enabling simultaneous transmission of the PUCCH and the PUSCH. In this case, since the PUCCH and the PUSCH are transmitted through separate carriers, there is no need to limit the type of PUCCH transmission performed simultaneously with the PUSCH transmission to HARQ feedback and CQI like the LTE REL-8 system. However, simultaneous transmission of different control information such as HARQ feedback and SR through PUCCH may increase the complexity of the terminal and the complexity of the base station.

Accordingly, in the present invention, even if the SR transmission time is overlapped with the PUSCH transmission time, the UE capable of simultaneous PUCCH and PUSCH transmission performs SR transmission simultaneously with PUSCH transmission even if HARQ feedback or CQI is not transmitted in the corresponding subframe. To this end, the UE reports whether the PUCCH and PUSCH can be simultaneously transmitted to the base station, and the base station determines whether to simultaneously transmit the PUCCH and PUSCH to the terminal in consideration of channel conditions. If the simultaneous transmission of the PUCCH and the PUSCH is determined, the UE determines whether to transmit the SR by checking whether the HARQ feedback or the CQI should be transmitted together in the subframe if the SR and the PUSCH should be transmitted simultaneously. Hereinafter, the operation of the terminal 405 and the base station 410 according to the present invention will be described in detail with reference to FIG. 4 again.

In step 420, it is assumed that a regular BSR is triggered. The regular BSR is triggered when a predetermined event occurs, for example, an event in which data of a higher priority occurs than data currently stored. Since the normal BSR needs to be delivered to the base station 410 quickly, when the regular BSR is triggered, the SR is triggered together in step 425. When the SR is triggered in step 425, the terminal 405 determines whether SR transmission is possible in every subframe. In step 430, the UE waits for a subframe in which a PUCCH resource for SR transmission is set. After this waiting, if the current subframe assumes that the PUCCH transmission resource is set, the UE 405 checks whether HARQ feedback or CQI transmission is necessary in the corresponding subframe. If HARQ feedback or CQI transmission is not necessary in the corresponding subframe, the UE 405 transmits an SR in the corresponding subframe in step 435. If HARQ feedback or CQI should be transmitted in the corresponding subframe, the UE 405 does not perform SR transmission in step 440 and waits until the next subframe in which the SR transmission resource is configured.

5 is a diagram illustrating a first operation of a terminal according to the present invention.

If the regular BSR is triggered in the terminal in step 505, the terminal proceeds to step 510 to trigger the SR. After the SR is triggered, the UE repeats operation 515 or less until the SR is canceled in order to determine whether to transmit the SR in each Transmission Time Interval (TTI).

In step 515, the UE checks whether transmission resources for uplink transmission in the corresponding TTI are not available, and whether PUCCH resources for SR transmission are not set in any TTI. If the check result is “Yes”, that is, if there is no transmission resource for backward transmission in the corresponding TTI, and if no PUCCH resource for SR transmission is set in any TTI, the UE proceeds to step 520 to initiate a random access procedure. Terminate the transfer process. In this case, the normal BSR triggered in step 505 may be transmitted to the base station through a random access process later.

On the other hand, if the check result of step 515 is "No", that is, if a transmission resource for uplink transmission is allocated in the corresponding TTI or PUCCH resources for SR transmission in at least one TTI is proceeded to step 525 .

In step 525, the UE checks whether a transmission resource for backward transmission is not allocated to the corresponding TTI and whether the corresponding TTI belongs to a subframe in which a PUCCH resource for SR transmission is set. If YES, go to step 535. If YES, go to step 530. The “No” means that a UE is allocated a transmission resource for uplink transmission to a corresponding TTI, and a PUCCH resource for SR transmission is also set to the corresponding TTI.

In step 530, according to the determination of “No”, the UE checks whether uplink transmission resources are available in the corresponding TTI, PUCCH resources for SR transmission are configured in the corresponding TTI, and the UE checks whether the SR transmission is possible in the corresponding TTI. do.

If simultaneous PUCCH and PUSCH transmission are configured and other PUCCH transmission such as HARQ feedback or CQI is not required for the corresponding TTI, the UE determines that SR transmission is possible in the corresponding TTI and proceeds to step 535.

If any one of the above two conditions is not satisfied, i.e., if PUCCH / PUSCH simultaneous transmission is not configured, or if another PUCCH transmission such as HARQ feedback or CQI is required for the corresponding TTI, the process proceeds to step 540 and waits for the next TTI. .

In step 535, the UE checks whether the corresponding TTI is not part of the measurement gap and whether the SR prohibit timer (sr-ProhibitTimer) is running.

If both conditions are satisfied, the terminal proceeds to step 545 to instruct the physical layer device to transmit the SR using the PUCCH transmission resource. If either of the two conditions is not satisfied, the terminal proceeds to step 540 and waits for the next TTI. For reference, the measurement gap refers to a “time interval in which transmission and reception is prohibited” that is set to measure another frequency band. In addition, the SR prohibit timer is a timer set to prevent excessive consumption of transmission resources due to an excessive number of SR transmissions. SR transmission is prohibited during a time when the SR prohibit timer is driven. do.

6 is a view for explaining a second operation of the terminal according to the present invention.

If the regular BSR is triggered in the terminal at step 605, the terminal proceeds to step 610 to trigger the SR. After the SR is triggered, the UE repeats operations 615 or less until the SR is canceled to determine whether to transmit the SR every TTI.

In step 615, the UE checks whether transmission resources for uplink transmission in the corresponding TTI are not available. If the transmission resources for uplink transmission in the corresponding TTI are not available, the terminal proceeds to step 625, and if available, proceeds to step 620.

In step 620, the UE checks whether SR transmission is possible in the corresponding TTI.

If the UE is a UE having simultaneous PUSCH and PUCCH transmissions and control information such as HARQ feedback or CQI is not transmitted in the corresponding TTI, the UE determines that SR transmission is possible in the corresponding TTI and proceeds to step 625.

If SR transmission is not possible in the corresponding TTI, the flow proceeds to step 635 and waits for the next TTI.

Meanwhile, in step 625, the UE checks whether the PUCCH transmission resource for SR transmission is set in any TTI. If "Yes", that is, if the PUCCH transmission resource for SR transmission is not configured in any TTI, the UE proceeds to step 645 to initiate a random access process and terminate the SR process.

If “No”, that is, if the PUCCH transmission resource for SR transmission is configured in at least one TTI, the terminal proceeds to step 630.

In step 630, the UE checks whether the PUCCH transmission resource for SR transmission is set in the corresponding TTI, the TTI is not part of a measurement gap, and the SR prohibit timer is not running. If all three conditions are satisfied, the terminal proceeds to step 640 to instruct the physical layer device to transmit the SR using the PUCCH transmission resource, and then proceeds to step 635 to wait until the next TTI.

If any one of the three conditions is not satisfied, that is, if the PUCCH transmission resource is not set in the corresponding TTI, the TTI is part of a measurement gap, or the SR prohibitTimer is running, step 635. Proceed directly to and wait until the next TTI.

7 is a diagram illustrating a configuration of a terminal device according to the present invention. Note that the upper layer device is not shown in the terminal device configuration diagram of FIG. 7.

Referring to FIG. 7, the terminal device includes a multiplexing and demultiplexing device 705, an HARQ processor 710, an SR / BSR controller 715, a MAC controller 720, and a transceiver 725.

The SR / BSR control unit 715 monitors whether data of a higher layer is generated or not to determine whether to trigger a BSR, triggers an SR transmission process when the BSR is triggered, determines whether to transmit an SR, and the transceiver transmits the SR accordingly. Control to initiate random access. That is, the SR / BSR controller 715 determines whether to transmit the SR of the present invention described with reference to FIGS. 4 to 6 and operates according to the determination result.

The MAC controller 720 interprets scheduling information received through the forward and reverse control channels and controls the transceiver to receive forward data or transmit reverse data. The multiplexing and demultiplexing apparatus controls to generate data to be transmitted in the reverse direction. When the SR / BSR controller 715 receives the UL grant, the SR / BSR controller 715 receives the UL grant to determine the cancellation of the SR transmission process and the BSR cancellation.

The transceiver 725 is a device that transmits and receives a MAC PDU (Media Access Control Packet Data Unit) or transmits and receives control information and receives a HARQ packet through a wireless channel. The HARQ processor 710 is a set of soft buffers configured to perform an HARQ operation and is identified by a HARQ process identifier. The multiplexing and demultiplexing apparatus 705 concatenates data transmitted from a plurality of logical channels to form a MAC PDU, or demultiplexes the MAC PDUs into MAC SDUs and delivers them to appropriate logical channels.

Claims (1)

A scheduling request method of a terminal in a wireless communication system,
When the scheduling request transmission time and the reverse data transmission time is the same, if the control information other than the scheduling request is not transmitted at the transmission time point, transmitting the scheduling request at the transmission time point of the terminal in the wireless communication system Scheduling request method.

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