KR102102666B1 - Method and apparatus for transmitting and receiving data using multiple carrier in mobile communication system - Google Patents

Abstract

A method for transmitting and receiving a signal in a terminal of a mobile communication system according to an embodiment of the present disclosure includes receiving a signal including transmission time interval setting (TTI) setting information for a specific cell from a base station; Checking a state of an uplink hybrid automatic repeat request (HARQ) buffer of the terminal; And when the TTI bundling configuration information is included in the configuration information, transmitting an uplink to the base station based on the configuration information and the uplink HARQ buffer status. According to one embodiment of the present specification, TTI bundling is used to improve uplink transmission efficiency of a terminal located in a cell change.

Description

Method and apparatus for transmitting and receiving data using multiple carriers in a mobile communication system {Method and apparatus for transmitting and receiving data using multiple carrier in mobile communication system}

The present specification relates to a method and apparatus for performing uplink transmission in a mobile communication system.

In general, mobile communication systems have been developed for the purpose of providing communication while securing user mobility. These mobile communication systems have reached the stage of providing high-speed data communication services as well as voice communication thanks to the rapid development of technology.

Recently, as one of the next generation mobile communication systems, 3GPP (3rd Generation Partnership Project) has been working on a specification for a Long Term Evolution (LTE) system. The LTE system is a technology for realizing high-speed packet-based communication that is significantly higher than the data rate currently being provided, and the current standardization is almost completed.

The uplink transmitted from the terminal to the base station has a limitation on the transmission output compared to the downlink transmitted from the base station to the terminal. This is due to the fact that the transmission power of the terminal is weaker than that of the base station. A terminal located in a cell change may experience a decrease in performance due to insufficient transmission power. Particularly, in LTE where the transmission time interval (TTI) is only 1 ms, this problem is more serious.

The LTE mobile communication system overcomes the above problem by using a technique called TTI bundling. In order for the TTI bundling to operate correctly, the UE and the base station must have the same understanding as to which uplink grant (UL grant) to apply TTI bundling and which UL grant does not apply TTI bundling.

One embodiment of the present specification is to solve at least some of the above problems, and an object thereof is to provide a method and apparatus for setting and releasing or resetting a TTI bundling pattern by a terminal and a base station.

In order to achieve the above-described problem, a method of transmitting and receiving a signal in a terminal of a mobile communication system according to an embodiment of the present specification provides a signal including transmission time interval (TTI) setting information for a specific cell from a base station. Receiving; Checking a state of an uplink hybrid automatic repeat request (HARQ) buffer of the terminal; And when the TTI bundling configuration information is included in the configuration information, transmitting an uplink to the base station based on the configuration information and the uplink HARQ buffer status.

A method for transmitting and receiving a signal in a base station of a mobile communication system according to another embodiment of the present disclosure includes transmitting a signal including transmission time interval setting information for a specific cell to a terminal; And receiving an uplink transmission from the terminal, wherein the terminal checks the state of an uplink hybrid automatic repeat request (HARQ) buffer of the terminal and silences TTI in the configuration information. ) If configuration information is included, the uplink is transmitted to the base station based on the configuration information and the uplink HARQ buffer status.

In a mobile communication system according to another embodiment of the present specification, a terminal for transmitting and receiving a signal includes a transceiver for transmitting and receiving a signal with a base station; And a transmission time interval (TTI) configuration information for a specific cell from the base station, and receiving the status of the uplink hybrid automatic retransmission request (Hybrid Automatic Repeat request, HARQ) buffer of the terminal. If it is checked, and the TTI bundling (bundling) configuration information is included in the configuration information, a control unit for transmitting an uplink to the base station based on the configuration information and the uplink HARQ buffer status.

In a mobile communication system according to another embodiment of the present specification, a base station for transmitting and receiving signals includes a transmitting and receiving unit for transmitting and receiving signals with a terminal; And a control unit receiving an uplink transmission from the terminal, wherein the terminal checks a state of an uplink hybrid automatic repeat request (HARQ) buffer of the terminal and silences TTI in the configuration information. ) If configuration information is included, the uplink is transmitted to the base station based on the configuration information and the uplink HARQ buffer status.

According to one embodiment of the present specification, TTI bundling is used to improve uplink transmission efficiency of a terminal located in a cell change.

1 is a diagram illustrating a structure of an LTE system to which some embodiments of the present specification are applied.
2 is a diagram illustrating a radio protocol structure in an LTE system to which some embodiments of the present specification are applied.
FIG. 3 is a diagram illustrating a process in which transmission time interval (TTI) bundling is set.
4 is a diagram illustrating an example of a TTI bundling operation.
5 is a view illustrating a pattern related to TTI bundling.
6 is a view for explaining an embodiment of the present disclosure as an example.
7 is a view for explaining the operation of the terminal of an embodiment of the present specification.
8 is a diagram for explaining a subframe and a pattern that has received a UL grant.
9A and 9B are diagrams illustrating that TTI bundling is started and a pattern is set in a handover process.
10 is a view for explaining the operation of the terminal to set the pattern in the handover process.
11 is a diagram for a starting point of a measurement gap (MG).
12 is a view for explaining the terminal operation of the second embodiment of the present specification.
13 is a diagram showing the structure of a terminal.
14 is a diagram showing the structure of a base station.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In describing the embodiments, descriptions of technical contents well known in the technical field to which the present invention pertains and which are not directly related to the present invention will be omitted. This is to more clearly convey the gist of the present invention by omitting unnecessary description.

For the same reason, some components in the accompanying drawings are exaggerated, omitted, or schematically illustrated. Also, the size of each component does not entirely reflect the actual size. The same reference numbers are assigned to the same or corresponding elements in each drawing.

In the following, when it is determined that a detailed description of known functions or configurations related to the specification may unnecessarily obscure the subject matter of the specification, the detailed description will be omitted. Hereinafter, embodiments of the present specification will be described with reference to the accompanying drawings. Hereinafter, the LTE system and carrier aggregation will be briefly described before describing the present specification.

1 is a diagram illustrating a structure of an LTE system to which some embodiments of the present specification are applied.

Referring to Figure 1, the radio access network of the LTE system is a next-generation base station (Evolved Node B, hereinafter referred to as ENB, Node B or base station) (105, 110, 115, 120) and MME (125, Mobility Management Entity) and S-GW (130, Serving-Gateway). User equipment (hereinafter referred to as UE or terminal) 135 connects to an external network through ENBs 105, 110, 115 and 120 and S-GW 130.

In FIG. 1, ENBs 105, 110, 115, and 120 correspond to existing Node Bs of the UMTS system. The ENB is connected to the UE 135 through a radio channel and performs a more complicated role than the existing Node B. In the LTE system, all user traffic, including real-time services such as Voice over IP (VoIP) through the Internet protocol, are serviced through a shared channel, so status information such as buffer status of UEs, available transmission power status, channel status, etc. It is necessary to have a device that collects and schedules scheduling, and ENB (105, 110, 115, 120) is responsible for this. One ENB usually controls multiple cells. In order to realize a transmission speed of 100 Mbps, the LTE system uses orthogonal frequency division multiplexing (hereinafter referred to as OFDM) as a radio access technology in a 20 MHz bandwidth. In addition, an adaptive modulation & coding (hereinafter referred to as AMC) method is applied to determine a modulation scheme and a channel coding rate according to a channel condition of a terminal. The S-GW 130 is a device that provides a data bearer, and creates or removes a data bearer under the control of the MME 125. MME is a device that is responsible for various control functions as well as mobility management functions for terminals, and is connected to multiple base stations.

2 is a diagram illustrating a radio protocol structure in an LTE system to which some embodiments of the present specification are applied.

Referring to FIG. 2, the radio protocol of the LTE system includes a PDCP (Packet Data Convergence Protocol 205, 240), an RLC (Radio Link Control 210, 235), and a MAC (Medium Access Control 215, 230) in the UE and the ENB, respectively. PDCP (Packet Data Convergence Protocol) (205, 240) is responsible for operations such as IP header compression / restoration, radio link control (Radio Link Control, hereinafter referred to as RLC) (210, 235) PDCP PDU (Packet Data Unit) ) To an appropriate size to perform ARQ operation. The MAC (215, 230) is connected to several RLC layer devices configured in one terminal, and performs an operation of multiplexing RLC PDUs to a MAC PDU and demultiplexing RLC PDUs from the MAC PDU. The physical layers 220 and 225 channel-code and modulate the upper layer data, make OFDM symbols, and transmit them on a wireless channel, or demodulate and demodulate the OFDM symbols received through the wireless channel and deliver them to the upper layer. .

3 is a diagram illustrating a TTI bundling operation in an LTE system to which some embodiments of the present specification are applied.

Referring to FIG. 3, in a mobile communication system composed of a terminal 305 and a base station 310, the terminal 305 moves to a change part of a cell and recognizes that the uplink transmission output is insufficient.

In step 315, the terminal 305 transmits a power headroom report (PHR) to the base station 310 and reports that the transmission power is insufficient. Operation of step 315 may be performed at any time.

In step 320, the base station 310 may determine to apply TTI bundling to the terminal 305. In an embodiment, the base station 310 may determine whether to apply TTI bundling based on the PHR received in step 315.

In step 325, the base station 310 may transmit an RRC connection reconfiguration message (RRCConnectionReconfiguration), which is a control message, to the terminal 305 based on the determination of step 320. In an embodiment, the RRC connection reconfiguration message may include ttiBundling, and in an embodiment, the field of the ttiBundling may be set to 'True'. In an embodiment, ttiBuyndling may instruct the terminal 305 whether or not TTI bundling is set, and the terminal 305 that receives and decodes the control message and interprets the content then transmits TTI bundling to PUSCH (Physical Uplink Shared Channel) transmission. Can be applied.

In step 330 of the embodiment, the terminal 305 processes the RRC control message for setting the TTI bundling, and if an UL grant is received in step 330, then in step 335, the terminal 305 performs TTI bundling applied transmission. .

Thereafter, for convenience of description, the terminal is set by the TTI bundling means that the terminal has completed processing of the RRC control message indicating the TTI bundling setting. The TTI bundling operation will be described in more detail below.

4 is a diagram illustrating an example of a TTI bundling operation.

Referring to FIG. 4, for example, in a subframe [0], the UE receives the first UL grant after TTI bundling is set (405).

The UE performs PUSCH transmission in sub-frames [4] through [7] (410).

HARQ (Hybrid Automatic Repeat reQuest) feedback for the bundled PUSCH transmission is transmitted and received in a sub-frame [11] (415).

If HARQ feedback NACK is received, the UE performs retransmission in subframes [20] to [23]. The retransmission is also bundled PUSCH transmission.

In an embodiment, new transmission or retransmission may be indicated in subframe [16] (420), and if a new transmission is indicated, new bundled PUSCH transmission is performed in subframes [20] to [23].

As seen above, the TTI bundling operation, when UL grant is received in sub-frame [n], bundled PUSCH transmission is performed over 4 sub-frames after 4 sub-frames, and retransmission is performed after 16 sub-frames. The bundled PUSCH transmission may collide with each other if the subframes in which the UL grant is transmitted and received are not spaced apart from each other by a multiple of 4 subframes. For example, when the UL grant is transmitted / received in sub-frame [n] and sub-frame [n + 3], bundled PUSCH transmission is sub-frame [n + 4] to sub-frame [n + 7] and sub-frame [n + 7] to sub It occurs in the frame [n + 10] and a collision may occur between two bundled PUSCH transmissions.

In order to prevent the collision, the terminal and the base station may determine the TTI bundling pattern when the first UL grant is transmitted and received after TTI bundling is set.

5 is a view illustrating a pattern related to TTI bundling.

Referring to FIG. 5, in the embodiment, when the first UL grant is received after TTI bundling is set in subframe [0] (535), a subframe in which UL grant for TTI bundling can be received at intervals of 4 subframes The pattern of them is decided.

That is, sub-frame [4] (540), sub-frame [8] (545), sub-frame [12] (550), consisting of sub-frame [16] (555), sub-frame [20] (560) UL grant pattern is formed. Subframe [4] to Subframe [7] (505), Subframe [8] to Subframe [11] (510), Subframe [12] to Subframe [15] (515), Subframe [16] ~ Subframe [19] (520), subframe [20] ~ subframe [23] (525), subframe [24] ~ subframe [27] (530) pattern diagram for bundled PUSCH transmission, etc. Is formed. In an embodiment, the UE may ignore UL grants that do not match the pattern.

As described above, it is simple to determine the pattern using the first UL grant after TTI bundling is set, but it is severe by the false positive UL grant (the UE detects the UL grant that the base station has not transmitted due to a CRC error). Errors may occur. That is, if the UE determines the pattern using the wrong first UL grant, then all correct UL grants can be ignored.

In an embodiment of the present disclosure, in order to solve the above problem, the terminal may determine the pattern using the UL grant received while all of the uplink HARQ buffers of the terminal are empty.

After transmitting the RRC control message for setting the TTI bundling, the base station may temporarily stop uplink scheduling for the terminal until all uplink HARQ buffers of the terminal are empty.

When all uplink HARQ buffers are empty, the base station transmits a UL grant to the terminal, and the terminal and the base station can set a pattern based on the UL grant.

That is, the terminal performs bundled PUSCH transmission for the UL grant that matches the pattern, and does not perform bundled PUSCH transmission for the UL grant that does not match the pattern, and ignores the corresponding UL grant. The base station transmits the UL grant only in sub-frames conforming to the pattern.

The uplink HARQ buffer stores PUSCH transmission data during the HARQ operation. The PUSCH transmission data is channel-coded by a MAC PDU (Media Access Control Packet Data Unit), and one MAC PDU is discarded from the corresponding HARQ buffer when a certain period is taken after transmission is started. In an embodiment, the predetermined period is determined by a parameter called maxHARQ-Tx. Therefore, even if the terminal initiated the bundled PUSCH transmission by the false positive UL grant, after the predetermined period of time, the uplink HARQ buffer is all empty (empty state), and when the base station transmits the UL grant, the UL The correct pattern can be set again by grant.

6 is a view for explaining an embodiment of the present disclosure as an example.

Referring to FIG. 6, when the UE receives the first UL grant after TTI bundling is set, the UE sets a pattern based on the subframe in which the UL grant is received (605). That is, the subframes spaced apart by the subframe in which the UL grant is received and the subframes of 4 subframes or a multiple of 4 are considered as subframes in which a valid UL grant can be received (610). In another embodiment, the four sub-frames may be sub-frames of different sizes.

After this, if the ongoing PUSCH transmission is finished at any time and all uplink HARQ buffers are empty (615), the UE releases the currently set pattern. That is, even if a UL grant that does not match the pattern is received, it is not ignored. Thereafter, if the first UL grant is received after the uplink HARQ buffer is empty at any time (620), the UE resets the pattern based on the received UL grant. That is, the subframes spaced by the subframe in which the UL grant is received and subframes of 4 subframes or multiples of 4 are regarded as subframes in which a valid UL grant can be received (625).

The terminal operation is illustrated in FIG. 7.

Referring to FIG. 7, in step 705, the UE receives an RRCConnectionReconfiguration message in which TTIbunling is set to True from the base station, and sets TTI bundling. Thereafter, the terminal performs the following operations until TTI bundling is released, that is, until the RRCConnectionReconfiguration message in which TTIbunling is set to False is received.

In step 710, the UE may determine whether all uplink HARQ buffers of the serving cell in which TTI bundling is set are empty. If all uplink HARQ buffers are empty according to the determination result, the process proceeds to step 715.

If the HARQ buffer is not empty, the terminal waits in step 710.

In addition, when carrier aggregation is used in an embodiment, multiple serving cells may be set in one terminal, and TTI bundling may be set in some of the serving cells, for example, PCell. A plurality of uplink HARQ buffers are provided for each serving cell, and in step 710, the UE checks an uplink HARQ buffer of a serving cell in which TTI bundling is set among several serving cells.

In step 715, the terminal releases the currently used pattern. To release the pattern, when a UL grant is received in an arbitrary subframe, whether the subframe in which the UL grant is received satisfies a predetermined condition, or PUSCH transmission generated by the UL grant satisfies a predetermined condition. It means that the operation of processing the UL grant and performing the bundled PUSCH transmission is no longer performed only if it is checked. According to an embodiment, when the pattern is released, when a UL grant is received in an arbitrary subframe, the received UL grant is ignored even if the subframe receiving the UL grant does not correspond to an existing applied pattern. You may not. The terminal that has released the pattern waits until the UL grant occurs, and when the UL grant occurs, the process proceeds to step 720.

The occurrence of the UL grant includes the case where one or more of the following conditions are satisfied.

-When a UL grant is received through a PDCCH, and the UL grant is addressed to the C-RNTI or Semi-Persistent Scheduling C-RNTI of the terminal. C-RNTI is an identifier of a terminal and is for dynamic transmission resource allocation. Semi-Persistent Scheduling C-RNTI is an identifier of a terminal and is for allocation of a semi-national transmission resource. Semi-Persistent Scheduling C-RNTI and Semi-Persistent Scheduling are described in more detail in 3GPP specification 36.321.

-When a UL grant is received through the PDCCH, and the UL grant is addressed to the Temporary C-RNTI of the terminal. Temporary C-RNTI is used in a random access process, and is for allocating transmission resources to a terminal whose contention has not been resolved (Contention resolution has not been completed).

-When a UL grant is received through RAR (Random Access Response).

-When the set UL grant occurs in the corresponding subframe. The set UL grant is related to a semi-permanently allocated transmission resource. If any transmission resource is allocated semi-permanently, it is considered that the UL grant for the transmission resource is periodically generated, and this UL grant is referred to as a set UL grant.

In step 720, the UE checks whether the UL grant satisfies the following conditions, and if all the conditions are satisfied, the process proceeds to step 730. If not, the terminal proceeds to step 725.

-Is TTI bundling set?

-Is TTI bundling UL grant for serving cell set?

-Are all uplink HARQ buffers of the serving cell configured with TTI bundling empty? At this time, the buffer storing Msg 3 is not considered. That is, if all other buffers are empty and Msg 3 is stored in an arbitrary buffer, it can be determined that the above condition is satisfied.

-Is UL grant for TTI bundle transmission?

  UL grant for TTI bundle transmission is a UL grant that triggers bundled PUSCH transmission and satisfies one or more of the following conditions.

-UL grant addressed to C-RNTI or Semi-Persistent Scheduling C-RNTI through a PDCCH among UL grants received for a serving cell in which TTI bundling is set while TTI bundling is set.

-UL grant occurred for a serving cell in which TTI bundling is set while TTI bundling is set

-UL grant stored in a valid RAR received in a random access process using a dedicated preamble in a serving cell with TTI bundling set while TTI bundling is set

That is, the UL grant received in the RAR received in the random access process using the random preamble, the UL grant for Msg 3 or the UL grant addressed as Temporary C-RNTI is not the UL grant for TTI bundling.

In step 725, the UE does not set a pattern with the UL grant. That is, if the pattern is already set, the pattern currently in use is maintained, and if the pattern is not set, the pattern unset status is maintained. And it is determined whether to process or ignore the received UL grant. If the UL grant is a UL grant received in the RAR received in the random access process in which the random preamble is used, that is, the UL grant for Msg 3, reverse transmission is performed according to the UL grant. If the UL grant is addressed as a Temporary C-RNTI, reverse transmission is performed according to the UL grant.

In step 730, the UE sets a pattern using the received UL grant, and applies this pattern to determine whether to perform bundled PUSCH transmission when a UL grant is received in the future. The operation of step 730 is described in detail in FIG. 8. After setting the pattern in step 730, if a UL grant is received through a PDCCH or a UL grant occurs in the future, if the UL grant occurs or the received subframe is a subframe that matches the pattern, the bundled PUSCH transmission is transmitted. If it does and does not conform to the pattern, that is, if the UL grant for TTI bundling is not a subframe that can be received, the UL grant is ignored and bundled PUSCH transmission is not performed.

In step 735, the UE waits until another UL grant occurs or the HARQ buffer is empty.

8 is a diagram for explaining a subframe and a pattern that has received a UL grant.

Referring to FIG. 8, if the UL grant is received in a subframe [n] through a PDCCH (805), the UE performs a UL grant for TTI bundling in the subframe [n + m * 4] (UL grant through RAR is Excluded, it is determined that bundled PUSCH transmission through UL grant through RAR is used only when the pattern is first set, and is not used after the pattern has already been set.). That is, it is determined that the pattern characterized by [n + m * 4] is set (810).

In this case, m is an integer greater than 1 or 1. If the UL grant is received in the sub-frame [n] through the RAR (815), the UE receives a UL grant for TTI bundling in the sub-frame [n + 2 + m * 4] (excluding the UL grant through the RAR). I think it can. That is, it is determined that the pattern specified by [n + 2 + m * 4] is set (820). In this case, m is an integer greater than 1 or 1.

The reason for distinguishing the two as described above is that the subframe in which the bundled PUSCH transmission is initiated is different when the UL grant is received through the PDCCH and when the UL grant is received through the RAR. When the UL grant is received in the sub-frame [n] through the PDCCH, the UE performs bundled PUSCH transmission in the sub-frame [n + 4] to sub-frame [n + 7] and receives the UL grant in the sub-frame [n] through the RAR. Upon reception, the UE performs bundled PUSCH transmission in sub-frame [n + 6] to sub-frame [n + 9]. Therefore, the pattern is formed differently when the UL grant is received through the PDCCH and the UL grant is received through the RAR. As described above, instead of defining separate rules for RAR and PDCCH, a pattern may be defined based on a time point when bundled PUSCH transmission starts. For example, if the bundled PUSCH transmission is initiated in subframe [k] by the UL grant received in subframe [k-4] or subframe [k-6] (825), the UE performs subframe [k + m * 4]. ], It is determined that UL grant for TTI bundling can be received. That is, it is determined that the pattern specified by [k + m * 4] is set (830).

TTI bundling may be set through a handover process. The handover entails a random access process, and according to the type of preamble used in the random access, the UE differentially selects a UL grant that sets a time and pattern at which TTI bundling starts.

9A and 9B are diagrams illustrating that TTI bundling is started and a pattern is set in a handover process.

9A and 9B, in a mobile communication system composed of a terminal 905, a cell 1 910, and a cell 2 915, the terminal 905 hands from a cell 1 910 to a cell 2 915. Receive a control message instructing it to go over. The cell 1 910 and the cell 2 915 may be different cells or the same cells. The control message may also include information to apply TTI bundling in cell 2 915.

The control message may also include information on cell 2 915, and in particular, dedicated preamble information may or may not be stored.

In an embodiment, if dedicated preamble information is not stored in the control message indicating the handover (920), the terminal 905 transmits a random preamble in cell 2 915 (925). If a valid random access response message (Random Access Response, RAR) corresponding to the random preamble is received at any time (930), the terminal 905 uses the Timing Advance information stored in the RAR to determine the reverse transmission timing. Adjust and prepare PUSCH transmission using UL grant. When the RAR is received in subframe n, PUSCH transmission is performed in subframe [n + k1]. K1 is an integer greater than or equal to 6. According to another embodiment, in FDD, K1 is 6, and in TDD, K1 may correspond to the first reverse subframe occurring after 6.

In the case of using the random preamble, the base station does not know who the terminal is in the step of transmitting the RAR. That is, it is impossible to determine whether the terminal is a terminal in which TTI bundling is set.

Therefore, if a random preamble is used, bundling is not applied to the UL grant of the RAR (935). In the random access process in which the random preamble is used, PUSCH transmission transmitted through the UL grant of the RAR is called Msg 3. The base station 915 receiving the Msg 3 transmits a contention resolution (CR) message to the terminal 905 (940).

The CR message is a DL assignment or UL grant addressed to the C-RNTI of the terminal 905. After the competition is resolved, the terminal 905 applies TTI bundling from the first UL grant, and sets a pattern based on the UL grant (943).

If a dedicated preamble is indicated in the control message indicating handover (945), the terminal 905 transmits the indicated dedicated preamble in cell 2 915 (950).

If the terminal 905 receives a valid random access response message (Random Access Response, RAR) corresponding to the dedicated preamble at any time (955), the terminal 905 uses the Timing Advance information stored in the RAR And adjust the reverse transmission timing to prepare for PUSCH transmission using UL grant. When the RAR is received in subframe n, PUSCH transmission is performed in subframe [n + k1]. K1 is an integer greater than or equal to 6. In FDD, K1 is 6, and in TDD, K1 corresponds to the first reverse subframe occurring after 6. When a dedicated preamble is used, the base station recognizes who the terminal is in the step of transmitting the RAR. That is, it is determined that the terminal is a terminal in which TTI bundling is set. If the UE uses a dedicated preamble, bundling is applied to the UL grant of the RAR (965). Then, the pattern is set based on the PUSCH transmission or the UL grant of the RAR.

The terminal operation is illustrated in FIG. 10.

Referring to FIG. 10, in step 1005, the UE receives an RRC CONNECTION RECONFIGURATION message indicating handover from the base station.

In step 1010, the terminal establishes forward synchronization with the cell indicated in the received message.

In step 1015, the UE determines whether a dedicated preamble is allocated in the RRC CONNECTION RECONFIGURATION message. In an embodiment, ra-PreambleIndex is stored in the RRC CONNECTION RECONFIGURATION message, and if the field is an integer between 1 and 63, a dedicate preamble is allocated. If the parameter is not stored or the parameter is stored, but the value is 0, a dedicated preamble is not assigned.

As a result of the determination in step 1015, if a dedicated preamble is allocated, the process proceeds to step 1020, and if not, the process proceeds to step 1045.

In step 1020, the UE transmits the preamble indicated by ra-PreambleIndex at a predetermined time point using a predetermined transmission resource. The time point for transmitting the preamble and the transmission resource may be known to the terminals as system information, and in the case of handover, the terminal is notified in an RRC CONNECTION RECONFIGURATION message indicating handover. The terminal transmits a preamble until the base station transmits a valid RAR within a predetermined number of times. The maximum number of times a terminal can transmit a preamble is regulated by preambleTransMax, and the value can be notified to the terminal through an RRC CONNECTION RECONFIGURATION message.

In step 1025, when the terminal receives a valid RAR, it is possible to adjust the backward transmission timing by applying the Timing Advance stored in the RAR. And it can be recognized that the reverse transmission should be performed using the UL grant indicated by the RAR. In an embodiment, a valid RAR may be a RAR including a preamble ID corresponding to a preamble transmitted by the UE in a sub-header.

In step 1030, the UE checks whether the ttiBundling parameter set to True is stored in the RRC CONNECTION RECONFIGURATION message indicating handover in order to determine whether to apply TTI bundling to reverse transmission using the reverse transmission resource allocated by the RAR. do. If so, you can proceed to step 1035, if not, to step 1040.

In step 1035, the UE may apply TTI bundling in performing reverse transmission using transmission resources allocated by the RAR. In other words, one MAC PDU is repeatedly transmitted by continuously using the transmission resource during TTIBUNDLESIZE TTI. And the terminal sets the pattern based on the time when the UL grant is received. A method corresponding to the previously described method may be applied to the pattern setting.

In step 1040, the UE may not apply TTI bundling in performing reverse transmission using the transmission resource allocated by the RAR. The terminal does not apply TTI bundling for subsequent backward transmission.

In step 1045, the UE randomly selects one preamble from a predetermined set of preambles and transmits it using a predetermined transmission resource at a predetermined time. When the preamble is transmitted and the transmission resource is known to the terminals as system information, in the case of handover, the terminal is notified in an RRC CONNECTION RECONFIGURATION message indicating handover. The terminal transmits a preamble until the base station transmits a valid RAR within a predetermined number of times. The maximum number of times a terminal can transmit a preamble is regulated by preambleTransMax, and the value is notified to the terminal through an RRC CONNECTION RECONFIGURATION message.

In step 1050, when the UE receives a valid RAR, the timing of the backward transmission is adjusted by applying the Timing Advance stored in the RAR. In addition, it is recognized that reverse transmission should be performed using the reverse transmission resource indicated by the RAR. A valid RAR is a RAR including a preamble ID corresponding to a preamble transmitted by a terminal in a sub header.

In step 1055, the UE does not apply TTI bundling and performs reverse transmission using transmission resources allocated by the RAR.

In step 1060, the UE then receives a reverse grant through the PDCCH or performs a TTI bundling when performing reverse transmission by the configured reverse grant, in order to determine whether to apply TTI bundling to True in the RRC CONNECTION RECONFIGURATION message instructing handover Check if the set ttiBundling parameter is stored. If so, go to step 1065, otherwise proceed to step 1070.

In step 1065, the UE applies TTI bundling from the UL grant that satisfies the following conditions and sets the pattern using the UL grant. The pattern setting was described above. The above conditions are as follows.

[UL grant to set TTI bundling pattern]

UL grants addressed to C-RNTI or Semi-Persistent Scheduling C-RNTI of the terminal, all of which are first received in an empty state except for the uplink HARQ buffer storing Msg 3; or

A UL grant received first among a UL grant first received after random access is completed or a UL grant completing random access; or

The first UL grant received after the competition cancellation is completed or the UL grant received first among the UL grants to resolve the competition.

Step 1070 may be the same as step 1040.

<2 Example>

In order to support the mobility of the terminal, the terminal is instructed to continuously measure the serving cell and surrounding cells. In particular, when the UE measures a neighboring cell having a frequency different from the current serving frequency, transmission / reception in the current serving cell should be stopped. During the UE measurement, in order to prevent the base station from degrading performance by transmitting data to the UE or scheduling an uplink, a time period during which the UE performs measurement on a non-serving frequency may be determined in advance. This time period may be referred to as a measurement gap (hereinafter referred to as MG).

11 is a diagram for a starting point of a measurement gap (MG).

Referring to FIG. 11, the terminal and the base station must have the same understanding of the time period during which MG occurs. Since the length of the MG is fixed to 6 ms, the above object can be achieved by notifying the UE of the subframe in which the MG starts. However, the start time of the subframe is not always the most ideal MG start time. For example, in a TDD system, a switching period having a length slightly longer than Timing Advance exists between an uplink subframe and a downlink subframe. In other combinations, for example, the gap does not exist between the uplink subframe and the uplink subframe, between the downlink subframe and the switching subframe, and between the switching subframe and the uplink subframe and is temporally adjacent to each other. For example, when the sub-frame [n-1] 1105 is an uplink sub-frame and the sub-frame [n] 1110 is a downlink sub-frame, a predetermined period between the sub-frame [n-1] and the sub-frame [n] There is a switching period 1115 of the length of. During the blank period, the terminal performs switching from the uplink to the downlink. When the MG is to be set before and after the switching period as described above, starting MG at a time 1125 when the sub-frame [n-1] ends starts MG at a time 1130 when the sub-frame [n] starts. It is more efficient than doing. In other cases, for example, in the case of setting MG based on sub-frame [n + 1], between starting at the end time of sub-frame [n] and starting at the start time of sub-frame [n + 1]. There is no difference.

In the exemplary embodiment of the present specification, the base station transmits predetermined parameters capable of determining the first subframe of the MG to the terminal, and the terminal and the base station determine the first subframe of the MG using the parameters. When the first sub-frame satisfies a predetermined condition, a method and apparatus for starting the MG at the end time of the sub-frame immediately before the first sub-frame are presented.

12 is a flowchart illustrating an operation of a terminal according to another embodiment of the present invention.

Referring to FIG. 12, in step 1200, the UE acquires system information of the serving cell, recognizes various information necessary for performing the RRC connection establishment procedure, and initiates an RRC connection establishment procedure with the serving cell.

In step 1215, the base station sets the MG to the terminal. MG is set by assigning a gapOffset to the terminal. As an example, gapOffset is divided into a first gapOffset having a value between 0 and 39 and a second gapOffset having a value between 0 and 79, and one of them is used. When the first gapOffset is signaled, the gap repetition period is 40 ms, and when the second gapOffset is signaled, the gap repetition period is 80 ms. More detailed description of the gapOffset and gap repetition period can be found in specifications 36.133 and 36.331.

In step 1220, the UE calculates a system frame number (SFN) and a subframe number specifying the first subframe of the MG. For example, the SFN of the radio frame to which the first sub-frame of the MG belongs may be calculated by <Equation 1>. For example, the subframe number of the first subframe of MG may be calculated by <Equation 2>. Hereinafter, for convenience of description, it is assumed that the first subframe of the MG is a subframe [n].

In step 1230, the UE checks whether the current operation mode is FDD or TDD. If it is FDD, it proceeds to step 1235, and if it is TDD, it proceeds to step 1240. In step 1235, the UE starts MG at the start time of the sub-frame [n].

In step 1240, the UE checks whether the subframe [n-1] is an uplink subframe and the subframe [n] is a downlink subframe, and if so, proceeds to step 1245. Otherwise, proceeds to step 1235. In step 1245, the UE starts MG when the sub-frame [n-1] ends. If multiple serving cells are configured in the terminal and two or more serving cells are active, the terminal among the multiple sub-frames [n-1], is the last (latest) sub-frame in time [n -1], MG is started. When multiple serving cells are set, it means that carrier aggregation is applied. Operations and activations during carrier aggregation are described in specifications 36.331 and 36.321.

Since the start time of [n] of the subframe and the end time of the subframe [n-1] are the same in step 1235, the operation of the terminal is simplified to start MG at the end time of the subframe [n-1] in step 1235 as well. You may.

 13 is a block diagram showing the configuration of a terminal according to an embodiment of the present invention.

Referring to FIG. 13, a terminal according to an embodiment of the present invention includes a transceiver 1305, a controller 1310, a multiplexing and demultiplexing unit 1315, a control message processing unit 1330, and various types of upper layer processing units 1320, 1325).

The transmission / reception unit 1305 receives data and a predetermined control signal in a forward channel of a serving cell and transmits data and a predetermined control signal in a reverse channel. When a plurality of serving cells are configured, the transceiver 1305 performs data transmission and reception and control signal transmission and reception through the plurality of serving cells.

The multiplexing and demultiplexing unit 1315 multiplexes data generated by the upper layer processing units 1320 and 1325 or the control message processing unit 1330 or demultiplexes the data received from the transmission / reception unit 1305 to appropriate upper layer processing units 1320, 1325) or control message processing unit 1330.

The control message processing unit 1330 is an RRC layer device and processes control messages received from a base station to perform necessary operations. For example, the RRC control message is received and TTI bundling related information and MG related information are transmitted to the control unit.

The upper layer processing units 1320 and 1325 may be configured for each service. Processes data generated from user services such as FTP (File Transfer Protocol) or Voice over Internet Protocol (VoIP) and transmits it to the multiplexing and demultiplexing unit 1315 or the data transmitted from the multiplexing and demultiplexing unit 1315 It is processed and delivered to the upper layer service application.

The control unit 1310 checks the scheduling command received through the transmission / reception unit 1305, for example, reverse grants, multiplexing and demultiplexing unit 1315 with the transmission / reception unit 1305 to perform reverse transmission with an appropriate transmission resource at an appropriate time. ) Control. The controller also oversees all procedures related to TTI bundling, and all procedures related to MG. That is, the terminal operation is controlled among the operations described in FIGS. 3 to 12.

14 is a block diagram showing the configuration of a base station according to an embodiment of the present invention, a transmitting and receiving unit 1405, a control unit 1410, a multiplexing and demultiplexing unit 1420, a control message processing unit 1435, each upper layer It includes a processing unit (1425, 1430), a scheduler (1415).

The transceiver 1405 transmits data and a predetermined control signal on a forward carrier and receives data and a predetermined control signal on a reverse carrier. When multiple carriers are set, the transceiver 1405 performs data transmission and reception and control signal transmission and reception with the multiple carriers.

The multiplexing and demultiplexing unit 1420 multiplexes data generated from the upper layer processing units 1425 and 1430 or the control message processing unit 1435 or demultiplexes the data received from the transmission / reception unit 1405 to appropriate upper layer processing units 1425, 1430) or the control message processor 1435 or the controller 1410. The control message processing unit 1435 processes the control message transmitted by the terminal and takes necessary operations or generates a control message to be delivered to the terminal and transmits it to the lower layer.

The upper layer processing units 1425 and 1430 may be configured for each bearer, and the data transmitted from the S-GW or another base station may be configured as an RLC PDU and transmitted to the multiplexing and demultiplexing unit 1420, or the multiplexing and demultiplexing unit 1420 ), The RLC PDU delivered from the PDCP SDU is configured and transmitted to the S-GW or another base station.

The scheduler allocates transmission resources to the terminal at an appropriate time in consideration of the buffer state and channel condition of the terminal, and processes the signal transmitted by the terminal to the transceiver and transmits the signal to the terminal.

The controller also oversees all procedures related to TTI bundling, and all procedures related to MG. That is, the base station operation related to the operations described in FIGS. 3 to 12 is controlled.

On the other hand, in the specification and drawings, preferred embodiments of the present invention have been disclosed, and although specific terms have been used, they are merely used in a general sense to easily describe the technical contents of the present invention and to help understand the invention. It is not intended to limit the scope of the invention. It is obvious to those skilled in the art to which the present invention pertains that other modifications based on the technical spirit of the present invention can be implemented in addition to the embodiments disclosed herein.

Claims (20)

In the method of transmitting and receiving a signal in a terminal of a mobile communication system,
Receiving a signal including a transmission time interval interval (TTI) bundling configuration information for a specific cell from a base station;
Receiving a first uplink grant (UL grant) from the base station;
Checking a state of an uplink hybrid automatic repeat request (HARQ) buffer of the terminal; And
And transmitting an uplink signal to the base station based on the configuration information and the uplink HARQ buffer status.
The step of transmitting the uplink signal,
Characterized in that it transmits an uplink signal to which TTI bundling is applied based on the UL grant that is additionally received in a subframe separated by a specific interval from the first UL grant and the subframe receiving the first UL grant. How to send and receive signals.
According to claim 1,
The step of transmitting the uplink signal,
When the buffer of the HARQ is empty when the first UL grant is received, TTI bundling is performed based on the UL grant additionally received in a subframe spaced apart by a specific interval from the subframe receiving the first UL grant. And transmitting the applied uplink signal.
According to claim 2,
The signal transmission and reception method
When the second UL grant is received in a subframe except for the subframe spaced apart by the specific interval, the second UL grant is ignored.
According to claim 2,
The step of transmitting the uplink signal is
After receiving the first UL grant, receiving a third UL grant; And
If the third UL grant is received while the uplink HARQ buffer is empty, and the third UL grant is for TTI bundle transmission, an uplink to which TTI bundling is applied is applied based on the third UL grant. Signal transmission and reception method comprising the step of performing a signal transmission.
According to claim 4,
The signal transmission and reception method
When the fourth UL grant is received in a subframe other than the subframe spaced apart by a specific interval from the subframe receiving the third UL grant, the signal transmission and reception method characterized in that the fourth UL grant is ignored.
In the method of transmitting and receiving signals at a base station of a mobile communication system,
Transmitting a signal including a transmission time interval interval (TTI) bundling configuration information for a specific cell to the terminal;
Transmitting a first uplink grant (UL grant) to the terminal; And
And receiving an uplink transmission from the terminal,
The terminal transmits an uplink to the base station based on the configuration information and the state of a hybrid automatic repeat request (HARQ) buffer of the terminal, but the first UL grant and the first UL A method for transmitting and receiving a signal, characterized in that an uplink signal to which TTI bundling is applied is transmitted based on a UL grant that is additionally received in a subframe separated by a specific interval from a subframe receiving the grant.
The method of claim 6,
The terminal
When the buffer of the HARQ is empty when the first UL grant is received, TTI bundling is performed based on the UL grant additionally received in a subframe spaced apart by a specific interval from the subframe receiving the first UL grant. Signal transmission and reception method, characterized in that for transmitting the applied uplink signal.
The method of claim 7,
The terminal
When the second UL grant is received in a subframe except for the subframe spaced apart by the specific interval, the second UL grant is ignored.
The method of claim 7,
The terminal
After receiving the first UL grant, a third UL grant is received, and the third UL grant is received while the uplink HARQ buffer is empty, and the third UL grant is for TTI bundle transmission , A signal transmission and reception method characterized in that the uplink signal transmission to which TTI bundling is applied is performed based on the third UL grant.
The method of claim 9,
The terminal
When the fourth UL grant is received in a subframe other than the subframe spaced apart by a specific interval from the subframe receiving the third UL grant, the signal transmission and reception method characterized in that the fourth UL grant is ignored.
In the terminal for transmitting and receiving a signal in a mobile communication system,
A transmitting and receiving unit that transmits and receives signals to and from a base station; And
Receives a signal including transmission time interval interval (TTI) bundling configuration information for a specific cell from the base station, and the uplink hybrid automatic repeat request (Hybrid Automatic Repeat request, HARQ) buffer of the terminal It includes a control unit for checking the status, and transmitting an uplink signal to the base station based on the configuration information and the uplink HARQ buffer status,
The control unit,
TTI based on the UL grant received in a subframe spaced apart by a specific interval from a subframe receiving a first UL grant from the base station and receiving the first UL grant and the first UL grant A terminal characterized by transmitting an uplink signal to which a bundling is applied.
The method of claim 11,
The control unit
When the buffer of the HARQ is empty when the first UL grant is received, TTI bundling is performed based on the UL grant additionally received in a subframe spaced apart by a specific interval from the subframe receiving the first UL grant. The terminal characterized in that it transmits the applied uplink signal.
The method of claim 12,
The control unit
When receiving the second UL grant in the sub-frame except for the sub-frame separated by the specific interval, the terminal characterized in that the second UL grant is ignored.
The method of claim 12,
The control unit
After receiving the first UL grant, a third UL grant is received, and the third UL grant is received while the uplink HARQ buffer is empty, and the third UL grant is for TTI bundle transmission , The terminal characterized in that for performing the uplink signal transmission is applied to the TTI bundling (bundling) based on the third UL grant.
The method of claim 14,
The control unit
When the fourth UL grant is received in the subframe except for the subframe spaced apart by a specific interval from the subframe receiving the third UL grant, the terminal characterized in that the fourth UL grant is ignored.
In the base station for transmitting and receiving a signal in a mobile communication system,
Transmitting and receiving unit for transmitting and receiving a signal with the terminal; And
It includes a control unit for receiving the uplink signal transmission from the terminal,
The control unit
A signal including a transmission time interval interval (TTI) bundling configuration information for a specific cell and a first uplink grant (UL grant) are transmitted to the terminal,
The terminal transmits an uplink signal to the base station based on the state of the uplink hybrid automatic repeat request (HARQ) buffer of the terminal, but receives the first UL grant and the first UL grant A base station characterized by transmitting an uplink signal to which TTI bundling is applied based on a UL grant that is additionally received in a subframe separated by a specific interval from a subframe.
The method of claim 16,
The terminal
When the buffer of the HARQ is empty when the first UL grant is received, TTI bundling is performed based on the UL grant additionally received in a subframe spaced apart by a specific interval from the subframe receiving the first UL grant. Base station characterized in that for transmitting the applied uplink signal.
The method of claim 17,
The terminal
When receiving a second UL grant in a subframe except for the subframe spaced apart by the specific interval, the base station characterized in that the second UL grant is ignored.
The method of claim 17,
The terminal
After receiving the first UL grant, a third UL grant is received, and the third UL grant is received while the uplink HARQ buffer is empty, and the third UL grant is for TTI bundle transmission , Based on the third UL grant, the base station characterized in that for performing the uplink signal transmission is applied TTI bundling (bundling).
The method of claim 19,
The terminal
When the fourth UL grant is received in a subframe except for a subframe spaced apart by a specific interval from the subframe receiving the third UL grant, the base station is characterized in that the fourth UL grant is ignored.

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