METHOD AND APPARATUS FOR PACKET TRANSMISSION AT SURVIVAL TIME STATE IN A WIRELESS COMMUNICATION SYSTEM

The present disclosure relates to a 5th generation (5G) or 6th generation (6G) communication system for supporting a higher data transmission rate. According to to an embodiment of the present disclosure, a method performed by a user equipment (UE) in a wireless communication system includes: receiving, from a base station, information on a configured grant allocating periodic resources for uplink transmissions; activating a packet duplication operation in case that an uplink transmission based on a resource allocated by the configured grant in a first cell is not successful; and performing the packet duplication operation based on a next resource allocated by the configured grant in the first cell and a second cell.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2022-0077564, filed on Jun. 24, 2022, in the Korean Intellectual Property Office, the present disclosure of which is incorporated by reference herein in its entirety.

BACKGROUND

The present disclosure relates to packet transmission method and apparatus in a survival time (ST) state of a wireless communication system.

2. Description of Related Art

SUMMARY

The present disclosure provides packet transmission method and apparatus in a survival time (ST) state of a wireless communication system.

According to an embodiment of the present disclosure, a method performed by a user equipment (UE) in a wireless communication system is provided. The method includes: receiving, from a base station, information on a configured grant allocating periodic resources for uplink transmissions; activating a packet duplication operation in case that an uplink transmission based on a resource allocated by the configured grant in a first cell is not successful; and performing the packet duplication operation based on a next resource allocated by the configured grant in the first cell and a second cell.

According to an embodiment of the present disclosure, a method performed by a base station in a wireless communication system is provided. The method includes: transmitting, to a user equipment (UE), information on a configured grant allocating periodic resources for uplink transmissions; identifying that an uplink transmission based on a resource allocated by the configured grant in a first cell is not successful; and receiving, from the UE, at least one duplicated packet from a next resource allocated by the configured grant in the first cell and a second cell.

According to an embodiment of the present disclosure, a user equipment (UE) in a wireless communication system is provided. The UE includes: a transceiver; and a controller configured to: receive, from a base station, information on a configured grant allocating periodic resources for uplink transmissions; activate a packet duplication operation in case that an uplink transmission based on a resource allocated by the configured grant in a first cell is not successful; and perform the packet duplication operation based on a next resource allocated by the configured grant in the first cell and a second cell.

According to an embodiment of the present disclosure, a base station in a wireless communication system is provided. The base station includes: a transceiver; and a controller configured to: transmit, to a user equipment (UE), information on a configured grant allocating periodic resources for uplink transmissions; identify that an uplink transmission based on a resource allocated by the configured grant in a first cell is not successful; and receive, from the UE, at least one duplicated packet from a next resource allocated by the configured grant in the first cell and a second cell.

According to an embodiment of the present disclosure, a service may be effectively provided.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure are described in detail with reference to the accompanying drawings. In this case, it is noted that like reference numerals denote like elements in the accompanying drawings. In addition, detailed descriptions related to well-known functions or configurations which may obscure the subject matter of the present disclosure shall be omitted.

Advantages and features of the present disclosure, and methods for achieving them will be clarified with reference to embodiments to be described below in detail together with the accompanying drawings. However, the present disclosure is not limited to the embodiments disclosed below but may be implemented in various different forms, the embodiments are provided to only complete the scope of the present disclosure and to allow those skilled in the art to which the present disclosure pertains to fully understand a category of the present disclosure, and the present disclosure is solely defined within the scope of the claims. The same reference numeral refers to the same element throughout the specification. Also, in describing the present disclosure, a detailed description of a related known function or configuration will be omitted if it is deemed to make the gist of the present disclosure unnecessarily vague. Terms to be described hereafter have been defined by taking into consideration functions in the present disclosure, and may be different depending on a user or an operator's intention or practice. Accordingly, they should be defined based on contents throughout the entire specification.

The description of embodiments of the present disclosure is mainly based on new radio (NR) which is a radio access network and a packet core 5th generation (5G) system, a 5G core network, or a next generation (NG) core which is a core network on 5G mobile communication standards specified by 3rd generation partnership project (3GPP) which is a mobile communication standardization organization, but the main subject of the present disclosure may be applied to other communication systems having a similar technical background with slight modification without departing from the scope of the present disclosure, which may be determined by those skilled in the art of the present disclosure.

Hereafter, terms and names defined in the 3GPP standard (standards for 5G, NR, long term evolution (LTE), or similar systems) may be used, for the convenience of description. However, the present disclosure is not limited by these terms and names, and may be applied in the same manner to systems conforming to other standards.

Hereafter, terms for identifying access nodes, terms indicating network entities, terms indicating messages, terms indicating interfaces between network entities, terms indicating various identification information, and the like are illustratively used in the description for the sake of convenience. Accordingly, the present disclosure is not limited by the terms as used, and other terms indicating subjects having equivalent technical meanings may be used.

Hereafter, a base station is an entity which performs resource assignment of a terminal, and may be at least one of a gNode B, an eNode B, a Node B, a base station (BS), a radio access unit, a BS controller and a node on a network. A terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smartphone, a computer and a multimedia system for performing a communication function. In the present disclosure, a downlink (DL) indicates a radio transmission path of a signal transmitted from the base station to the terminal, and an uplink (UL) indicates a radio transmission path of a signal transmitted from the terminal to the base station.

At this time, it will be understood that each block of the process flowchart illustrations and combinations of the flowchart illustrations may be executed by computer program instructions. Since these computer program instructions may be mounted on a processor of a general purpose computer, a special purpose computer or other programmable data processing apparatus, the instructions executed by the processor of the computer or other programmable data processing equipment may generate means for executing functions described in the flowchart block(s). Since these computer program instructions may also be stored in a computer-usable or computer-readable memory which may direct a computer or other programmable data processing equipment to function in a particular manner, the instructions stored in the computer-usable or computer-readable memory may produce a manufacture article including instruction means which implement the function described in the flowchart block(s). Since the computer program instructions may also be loaded on a computer or other programmable data processing equipment, a series of operational steps may be performed on the computer or other programmable data processing equipment to produce a computer-executed process, and thus the instructions performing the computer or other programmable data processing equipment may provide steps for executing the functions described in the flowchart block(s).

In addition, each block may represent a portion of a module, a segment or code which includes one or more executable instructions for implementing a specified logical function(s). Also, it should be noted that the functions mentioned in the blocks may occur out of order in some alternative implementations. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order depending on corresponding functionality.

At this time, the term “˜unit” as used in the present embodiment indicates software or a hardware component such as a field programmable gate array (FPGA) or an application-specific integrated circuit (ASIC), and “˜unit” performs specific roles. However, “˜unit” is not limited to software or hardware. “˜unit” may be configured to reside on an addressable storage medium and configured to reproduce on one or more processors. Accordingly, “˜unit” may include, for example, components such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, sub-routines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. The functionalities provided in the components and “˜unit” may be combined to fewer components and “˜units” or may be further separated into additional components and “˜units.” Further, the components and “˜units” may be implemented to reproduce one or more central processing units (CPUs) within a device or a security multimedia card. Also, “˜unit” in the embodiment may include one or more processors.

A wireless communication system is evolving from its early voice-oriented service to, for example, a broadband wireless communication system which provides high-speed, high-quality packet data services according to communication standards such as high speed packet access (HSPA) of 3GPP, LTE or evolved universal terrestrial radio access (E-UTRA), LTE-advanced (A), LTE-Pro, high rate packet data (HRPD) of 3GPP2, ultra mobile broadband (UMB), and institute of electrical and electronics engineers (IEEE) 802.16e.

As a representative example of the broadband wireless communication system, the LTE system employs an orthogonal frequency division multiplexing (OFDM) scheme in the DL, and a single carrier frequency division multiple access (SC-FDMA) scheme in the UL. The UL indicates a radio link through which the UE or the MS transmits data or a control signal to the eNB or the BS, and the DL indicates a radio link through which the eNB transmits data or a control signal to the UE. A multi-access scheme distinguishes data or control information of each user by assigning and operating time-frequency resources for carrying the data or the control information of each user not to overlap, that is, to establish orthogonality.

A future communication system after the LTE, that is, the 5G communication system, which should be able to freely reflect various requirements of users and service providers, needs to support a service for simultaneously satisfying various requirements. Services considered for the 5G communication system include enhanced mobile broadband (eMBB), massive MTC (mMTC), ultra reliability low latency communication (URLLC) and so on.

The eMBB aims to provide a faster data rate than a data rate supported by existing LTE, LTE-A or LTE-Pro. For example, the eMBB in the 5G communication system should be able to provide a peak data rate of 20 gigabits per second (Gbps) in the DL and 10 Gbps in the UL in terms of one base station. In addition, the 5G communication system should provide the peak data rate and concurrently provide an increased user perceived data rate of the terminal. To satisfy these requirements, improvements of various transmission and reception technologies are required, including a further advanced multi input multi output (MIMO) transmission technology. In addition, while signals are transmitted using a maximum 20 megahertz (MHz) transmission bandwidth in a 2 GHz band used by the LTE, the 5G communication system uses a frequency bandwidth wider than 20 MHz in the frequency band of 3-6 GHz or 6 GHz or higher, thus satisfying the required data rate in the 5G communication system.

At the same time, the 5G communication system is considering the mMTC to support application services such as IoT. The mMTC requires large-scale terminal access support in a cell, terminal coverage enhancement, improved battery time, and terminal cost reduction to efficiently provide the IoT. The IoT is attached to various sensors and various devices to provide communication functions and accordingly should be able to support a great number of terminals (e.g., 1,000,000 terminals/km2) in the cell. In addition, the terminal supporting the mMTC is highly likely to be located in a shaded area not covered by the cell such as a basement of building due to its service characteristics, and thus may require wider coverage than other services provided by the 5G communication system. A terminal supporting the mMTC should be configured with a low-priced terminal, and may require a quite long battery lifetime such as 10˜15 years because it is difficult to frequently replace the battery of the terminal.

Finally, the URLLC is a cellular-based wireless communication service used for mission-critical purposes, and may be used for robot or machinery remote control, industrial automation, unmanaged aerial vehicle, remote health care, emergency alert, or the like. Thus, the communication provided by the URLLC should provide very low latency (ultra low latency) and very high reliability (ultra high reliability). For example, a service supporting the URLLC should meet air interface latency smaller than 0.5 milliseconds and at the same time has requirements of a packet error rate below 10−5. Hence, for the service supporting the URLLC, the 5G system should provide a transmit time interval (TTI) smaller than other services, and concurrently requires design issues for allocating a wide resource in the frequency band to obtain communication link reliability.

The three services of the 5G communication system, that is, the eMBB, the URLLC, and the mMTC may be multiplexed and transmitted in one system. In this case, to satisfy the different requirements of the respective services, different transmission and reception schemes and transmission and reception parameters may be used between the services. Notably, the 5G communication system is not limited to the three services mentioned above.

FIG.1illustrates an example of survival time (ST)-state entry and wireless communication system operations according to embodiments of the present disclosure.

A specific application layer service of the wireless communication system may include a URLLC service. The URLLC service, which is to ensure high reliability within a short time, needs to use considerable radio resources.

For the URLLC service, a packet duplication scheme which pre-allocates a UL configured grant (CG) resource periodically allocated, and if URLLC service data occurs, duplicates a packet, and transmits the corresponding packet with a different CG resource using a close CG resource may be considered. However, the packet duplication may degrade resource efficiency because the packet is transmitting using two or more radio resources. Since the wireless communication system has limited radio resources, this packet duplication scheme may degrade a throughput of the wireless communication system, which may be a burden on the wireless communication system. Hence, a method for reducing the radio resource usage and supporting the URLLC service is demanded.

Referring toFIG.1, periodic CG resources120,130,160and170are configured in a first cell110and a second cell150. The CGs120and130of the first cell110may be used by a first logical channel (LCH), and the CGs160and170of the second cell150may be used by a second LCH. In this case, it is assumed that the first LCH and the second LCH are connected to a common radio bearer. In other words, one packet data convergence protocol (PDCP) entity corresponding to the common radio bearer may correspond to two radio link control (RLC) entities, and the RLC entities may correspond to the first LCH and the second LCH, respectively. In the above embodiment, it is described that the one PDCP entity corresponds to the two RLC entities, which is not limited thereto, but one PDCP entity may correspond to two or more RLC entities.

InFIG.1, the packet duplication is activated by hybrid automatic repeat request (HARQ) negative-acknowledgement (NACK) indicating resource allocation for CC retransmission. As described earlier, since the packet duplication scheme may degrade the radio resource efficiency, it may be not advantageous to always use the packet duplication. It is assumed inFIG.1that only the CG120of the first cell110is used for the packet transmission, and the CG160of the second cell150is not used for the packet transmission. That is, it may be assumed that the packet duplicate transmission is not activated. In this case, since the RLC entity for using the CG160of the second cell150does not transmit an RLC protocol data unit (PDU) (corresponding to a media access control (MAC) service data unit (SDU)) to an MAC entity, the MAC PDU to be transmitted by the CG160of the second cell150is not generated. Hence, the CG160of the second cell150is not used.

Next, if the MAC PDU transmission based on the CG120of the first cell110is not successful, a base station may allocate a retransmission resource for the CG120. This retransmission resource may be allocated using a new data indicator (NDI) field in a downlink control information (DCI) message using a configured scheduling (CS)-radio network temporary identifier (RNTI). More specifically, the retransmission resource may be allocated by setting the NDI field of the DCI message transmitted over a physical downlink control channel (PDCCH) scrambled with the CS-RNTI to 1. If a terminal is allocated the retransmission resource for the CG, this may indicate that the base station does not successfully receive the CG transmission, and accordingly the resource allocation for the CG retransmission may be considered as the HARQ NACK121.

As described above, if the NDI field of the DCI message using the CS-RNTI is set to 1 and the retransmission resource is allocated, the packet duplicate transmission may be activated using the configured RLC entity. As such, a state which packet duplicate transmission is activated may be referred to as a survival time state (ST-state)122. In this case, the ST indicates a time for surviving from packet loss. If the packet loss is not restored before the ST expires, application layer service requirements may not be satisfied. Thus, the ST-state may require higher reliability transmission.

As aforementioned inFIG.1, if the NDI field of the DCI message using the CS-RNTI is set to 1 and the retransmission resource is allocated, the ST-state is entered and the packet duplicate transmission is activated using the configured RLC entity. Since the packet duplicate transmission is activated, the terminal may perform the packet duplicate transmission using both the RLC entity corresponding to the CG130of the first cell110and the RLC entity corresponding to the CG170of the second cell150. That is, the packet duplicate transmission may be performed using the CG130of the first cell110and the CG170of the second cell150. The packet duplicate transmission activation indication or configuration may be forwarded from the MAC entity of the terminal to the PDCP entity which is an upper layer.

In an embodiment, the aforementioned ST-state operations may be performed only at the configured radio bearer. The ST-state operation may be configured by the base station for the terminal with a radio resource control (RRC) message.

FIG.2illustrates another example of ST-state entry and wireless communication system operations according to embodiments of the present disclosure.

Referring toFIG.2, periodic CG resources220,230,260, and270are configured in a first cell210and a second cell250. The CGs220and230of the first cell210may be used by a first LCH, and the CGs260and270of the second cell250may be used by a second LCH. In this case, it is assumed that the first LCH and the second LCH are connected to a common radio bearer. In other words, one PDCP entity corresponding to the common radio bearer may correspond to two RLC entities, and the RLC entities may correspond to the first LCH and the second LCH, respectively. In the above embodiment, it is described that the one PDCP entity corresponds to the two RLC entities, which is not limited thereto, but one PDCP entity may correspond to two or more RLC entities.

FIG.2illustrates the packet duplication activation by de-prioritization of the CC resource on which transmission is performed. As aforementioned, since the packet duplication scheme may degrade the radio resource efficiency, it may be not advantageous to always use the packet duplication. It is assumed inFIG.2that only the CG220of the first cell210is used for the packet transmission, and the CG260of the second cell250is not used for the packet transmission. That is, it may be assumed that the packet duplicate transmission is not activated. In this case, since the RLC entity for using the CG260of the second cell250does not transmit an RLC PDU (corresponding to a MAC SDU) to an MAC entity, the MAC PDU to be transmitted by the CG260of the second cell250is not generated. Hence, the CG260of the second cell250is not used.

However, if the CG220of the first cell210is de-prioritized by other UL radio resource overlapping on the time domain in a bandwidth part (BWP), the CG is not transmitted.FIG.2illustrates that the CG resource220overlaps other dynamic grant (DG) resource on the time domain and the DG resource is prioritized to de-prioritize the CG220of the first cell210, which is not limited thereto, but the above embodiment may be applied even if the CG220of the first cell210is de-prioritized by a scheduling request message or other different transmission.

If the CG resource is de-prioritized, which may indicate that the base station does not successfully receive the CG transmission, the packet duplicate transmission may be activated. In this case, the packet duplicate transmission may be activated using every configured RLC entity. As such, a state which the packet duplicate transmission is activated may be referred to as an ST-state222. At this time, the ST indicates the time for surviving from packet loss. If the packet loss is not restored before the ST expires, application layer service requirements may not be satisfied. Thus, the ST-state may require higher reliability transmission.

FIG.2illustrates that, if the CG resource is de-prioritized, the ST-state is entered and the packet duplicate transmission is activated using the configured RLC entity. Since the packet duplicate transmission is activated, the terminal may perform the packet duplicate transmission using both the RLC entity corresponding to the CG230of the first cell210and the RLC entity corresponding to the CG270of the second cell250. That is, the packet duplicate transmission may be performed using the CG230of the first cell210and the CG270of the second cell250. The packet duplicate transmission activation indication or configuration may be forwarded from the MAC entity of the terminal to the PDCP entity which is an upper layer.

In an embodiment, the aforementioned ST-state operations may be performed only at the configured radio bearer. The ST-state operation may be configured by the base station for the terminal with an RRC message.

FIG.3illustrates yet another example of ST-state entry and wireless communication system operations according to embodiments of the present disclosure.

Referring toFIG.3, periodic CG resources320,330,360, and370are configured in a first cell310and a second cell350. The CGs320and330of the first cell310may be used by a first LCH, and the CGs360and370of the second cell350may be used by a second LCH. In this case, it is assumed that the first LCH and the second LCH are connected to a common radio bearer. In other words, one PDCP entity corresponding to the common radio bearer may correspond to two RLC entities, and the RLC entities may correspond to the first LCH and the second LCH, respectively. In the above embodiment, it is described that the one PDCP entity corresponds to the two RLC entities, which is not limited thereto, but one PDCP entity may correspond to two or more RLC entities.

FIG.3illustrates that the packet duplication is activated by listen before talk (LBT) failure of the CC resource on which transmission is performed. As aforementioned, since the packet duplication scheme may degrade the radio resource efficiency, it may be not advantageous to always use the packet duplication. It is assumed inFIG.3that only the CG320of the first cell310is used for the packet transmission, and the CG360of the second cell350is not used for the packet transmission. That is, it may be assumed that the packet duplicate transmission is not activated. In this case, since the RLC entity for using the CG360of the second cell350does not transmit an RLC PDU (corresponding to a MAC SDU) to an MAC entity, the MAC PDU to be transmitted by the CG360of the second cell350is not generated. Hence, the CG360of the second cell350is not used.

However, before the transmission using the CG resource320of the first cell310, if an unlicensed band of the first cell310is used by another radio technology, the LBT failure is declared. If the LBT failure is declared on the CG320transmission, the CG320is not transmitted. If the CG320is not transmitted due to the LBT failure, which may indicate that the base station does not successfully receive the CG transmission, the packet duplicate transmission may be activated. In this case, the packet duplicate transmission may be activated using every configured RLC entity. As such, a state which the packet duplicate transmission is activated may be referred to as an ST-state322. At this time, the ST indicates the time for surviving from packet loss. If the ST expires and the packet loss is not restored, application layer service requirements may not be satisfied. Hence, the ST-state may require higher reliability transmission.

FIG.3illustrates that, if the CG320is not transmitted due to the LBT failure, the ST-state is entered and the packet duplicate transmission is activated using the configured RLC entity. Since the packet duplicate transmission is activated, the terminal may perform the packet duplicate transmission using both the RLC entity corresponding to the CG330of the first cell310and the RLC entity corresponding to the CG370of the second cell350. That is, the packet duplicate transmission may be performed using the CG330of the first cell310and the CG370of the second cell350. The packet duplicate transmission activation indication or configuration may be forwarded from the MAC entity of the terminal to the PDCP entity which is an upper layer.

In an embodiment, the aforementioned ST-state operations may be performed only at the configured radio bearer. The ST-state operation may be configured by the base station for the terminal with an RRC message.

FIG.4illustrates yet another example of ST-state entry and wireless communication system operations according to embodiments of the present disclosure.

Referring toFIG.4, periodic CG resources420,430,460and470are configured in a first cell410and a second cell450. The CGs420and430of the first cell410may be used by a first LCH, and the CGs460and470of the second cell450may be used by a second LCH. In this case, it is assumed that the first LCH and the second LCH are connected to a common radio bearer. In other words, one PDCP entity corresponding to the common radio bearer may correspond to two RLC entities, and the RLC entities may correspond to the first LCH and the second LCH, respectively. In the above embodiment, it is described that the one PDCP entity corresponds to the two RLC entities, which is not limited thereto, but one PDCP entity may correspond to two or more RLC entities.

FIG.4illustrates that the packet duplication is activated if the packet is not transmitted by a resource allocated in a random access process of the CC resource on which transmission is performed. The resource allocated in the random access process may be one of a DG resource allocated in a random access response (RAR) message, a DG resource allocated using a temporary C-RNTI, or a message A (MSGA) payload. As aforementioned, since the packet duplication scheme may degrade the radio resource efficiency, it may be not advantageous to always use the packet duplication. It is assumed inFIG.4that only the CG420of the first cell410is used for the packet transmission, and the CG460of the second cell450is not used for the packet transmission. That is, it may be assumed that the packet duplicate transmission is not activated. In this case, since the RLC entity for using the CG460of the second cell450does not transmit an RLC PDU (corresponding to a MAC SDU) to an MAC entity, the MAC PDU to be transmitted by the CG460of the second cell450is not generated. Hence, the CG460of the second cell450is not used.

However, if there is the resource allocated in the random access process overlapping the CG420of the first cell410on the time domain within the BWP, the allocated resource is transmitted in the random access process and the CG420is not transmitted.FIG.4illustrates that the CG resource420overlaps the DG resource allocated in the RAR message on the time domain, but the embodiment ofFIG.4may be applied even if the CG420is not transmitted by the DG resource allocated using the temporary C-RNTI, or the MSGA payload. Since transmitting no CC resource with the resource allocated in the random access process may indicate that the base station does not successfully receive the CG transmission, the packet duplicate transmission may be activated. In this case, the packet duplicate transmission may be activated using every configured RLC entity. As such, a state which the packet duplicate transmission is activated may be referred to as an ST-state422. At this time, the ST indicates the time for surviving packet loss. If the packet loss is not restored before the ST expires, application layer service requirements may not be satisfied. Thus, the ST-state may require higher reliability transmission.

FIG.4illustrates that, if the CC resource is not transmitted by the resource allocated in the random access process, the ST-state is entered and the packet duplicate transmission is activated using the configured RLC entity. Since the packet duplicate transmission is activated, the terminal may perform the packet duplicate transmission using both the RLC entity corresponding to the CG430of the first cell410and the RLC entity corresponding to the CG470of the second cell450. That is, the packet duplicate transmission may be performed using the CG430of the first cell410and the CG470of the second cell450. The packet duplicate transmission activation indication or configuration may be forwarded from the MAC entity of the terminal to the PDCP entity which is an upper layer.

In an embodiment, the aforementioned ST-state operations may be performed only at the configured radio bearer. The ST-state operation may be configured by the base station for the terminal with an RRC message.

FIG.5illustrates yet another example of ST-state entry and wireless communication system operations according to embodiments of the present disclosure.

Referring toFIG.5, periodic CG resources520,530,560and570are configured in a first cell510and a second cell550. The CGs520and530of the first cell510may be used by a first LCH, and the CGs560and570of the second cell550may be used by a second LCH. In this case, it is assumed that the first LCH and the second LCH are connected to a common radio bearer. In other words, one PDCP entity corresponding to the common radio bearer may correspond to two RLC entities, and the RLC entities may correspond to the first LCH and the second LCH, respectively. In the above embodiment, it is described that the one PDCP entity corresponds to the two RLC entities, which is not limited thereto, but one PDCP entity may correspond to two or more RLC entities.

FIG.5illustrates that the packet duplication is activated by CG transmission cancellation. As aforementioned, since the packet duplication scheme may degrade the radio resource efficiency, it may be not advantageous to always use the packet duplication. It is assumed inFIG.5that only the CG520of the first cell510is used for the packet transmission, and the CG560of the second cell550is not used for the packet transmission. That is, it may be assumed that the packet duplicate transmission is not activated. In this case, since the RLC entity for using the CG560of the second cell550does not transmit an RLC PDU (corresponding to a MAC SDU) to an MAC entity, the MAC PDU to be transmitted by the CG560of the second cell550is not generated. Hence, the CG560of the second cell550is not used.

However, if the CG520of the first cell510is cancelled due to transmission using cancellation indication (CI)-RNTI521in the PDCCH, the transmission of the CG520is immediately cancelled and the complete CG transmission is not performed. The cancelled CG resource may become de-prioritized uplink grant. If the CG resource transmission is cancelled, which may indicate that the base station does not successfully receive the CG transmission, the packet duplicate transmission may be activated. In this case, the packet duplicate transmission may be activated using every configured RLC entity. As such, a state which the packet duplicate transmission is activated may be referred to as an ST-state522. At this time, the ST indicates the time for surviving from packet loss. If the ST expires and the packet loss is not restored, application layer service requirements may not be satisfied. Thus, the ST-state may require higher reliability transmission.

It has been illustrated in the embodiment ofFIG.5that, if the CC resource is cancelled by the CI-RNTI, the ST-state is entered and the packet duplicate transmission is activated using the configured RLC entity. Since the packet duplicate transmission is activated, the terminal may perform the packet duplicate transmission using both the RLC entity corresponding to the CG530of the first cell510and the RLC entity corresponding to the CG570of the second cell550. That is, the packet duplicate transmission may be performed using the CG530of the first cell510and the CG570of the second cell550. The packet duplicate transmission activation indication or configuration may be forwarded from the MAC entity of the terminal to the PDCP entity which is an upper layer.

In an embodiment, the aforementioned ST-state operations may be performed only at the configured radio bearer. The ST-state operation may be configured by the base station for the terminal with an RRC message.

FIG.6illustrates yet another example of ST-state entry and wireless communication system operations according to embodiments of the present disclosure.

Referring toFIG.6, periodic CG resources620,630,660, and670are configured in a first cell610and a second cell650. The CGs620and630of the first cell610may be used by a first LCH, and the CGs660and670of the second cell650may be used by a second LCH. In this case, it is assumed that the first LCH and the second LCH are connected to a common radio bearer. In other words, one PDCP entity corresponding to the common radio bearer may correspond to two RLC entities, and the RLC entities may correspond to the first LCH and the second LCH, respectively. In the above embodiment, it is described that the one PDCP entity corresponds to the two RLC entities, which is not limited thereto, and one PDCP entity may correspond to two or more RLC entities.

FIG.6illustrates that the packet duplication is activated by downlink feedback information (DFI)-NACK indicating no reception of the CG transmission. The DFI-NACK may be a message used for the base station to notify the terminal of transport block (TB) transmission failure for the uplink grant in the unlicensed band. Since the packet duplication scheme may degrade the radio resource efficiency as mentioned above, it may be not advantageous to always use the packet duplication. It is assumed inFIG.6that only the CG620of the first cell610is used for the packet transmission, and the CG660of the second cell650is not used for the packet transmission. That is, it may be assumed that the packet duplicate transmission is not activated. In this case, since the RLC entity for using the CG660of the second cell650does not transmit an RLC PDU (corresponding to a MAC SDU) to an MAC entity, the MAC PDU to be transmitted by the CG660of the second cell650is not generated. Hence, the CG660of the second cell650is not used.

If the MAC PDU transmission with the CG620of the first cell610is not successful, the base station may transmit the DFI-NACK621for the transmission of the CG620to the terminal. If the terminal receives the DFI-NACK of the CG resource, which may indicate that the base station does not successfully receive the CG transmission, the packet duplicate transmission may be activated. In this case, the packet duplicate transmission may be activated using every configured RLC entity. As such, a state which the packet duplicate transmission is activated may be referred to as an ST-state622. At this time, the ST indicates the time for surviving from packet loss. If the ST expires and the packet loss is not restored, application layer service requirements may not be satisfied. Hence, the ST-state may require higher reliability transmission.

It has been illustrated in the embodiment ofFIG.6that, if the terminal receives the DFI-NACK, the ST-state is entered and the packet duplicate transmission is activated using the configured RLC entity. Since the packet duplicate transmission is activated, the terminal may perform the packet duplicate transmission using both the RLC entity corresponding to the CG630of the first cell610and the RLC entity corresponding to the CG670of the second cell650. That is, the packet duplicate transmission may be performed using the CG630of the first cell610and the CG670of the second cell650. The packet duplicate transmission activation indication or configuration may be forwarded from the MAC entity of the terminal to the PDCP entity which is an upper layer.

In an embodiment, the aforementioned ST-state operations may be performed only at the configured radio bearer. The ST-state operation may be configured by the base station for the terminal with an RRC message.

FIG.7illustrates yet another example of ST-state entry and exit, and wireless communication system operations according to embodiments of the present disclosure.

Referring toFIG.7, periodic CG resources720,730,760, and770are configured in a first cell710and a second cell750. The CGs720and730of the first cell710may be used by a first LCH, and the CGs760and770of the second cell750may be used by a second LCH. In this case, it is assumed that the first LCH and the second LCH are connected to a common radio bearer. In other words, one PDCP entity corresponding to the common radio bearer may correspond to two RLC entities, and the RLC entities may correspond to the first LCH and the second LCH, respectively. In the above embodiment, it is described that the one PDCP entity corresponds to the two RLC entities, which is not limited thereto, and one PDCP entity may correspond to two or more RLC entities.

FIG.7illustrates that the packet duplication is activated by DFI-NACK indicating no reception of the CG transmission. The DFI-NACK may be a message used for the base station to notify the terminal of TB transmission failure for the uplink grant in the unlicensed band. As aforementioned, since the packet duplication scheme may degrade the radio resource efficiency, it may be not advantageous to always use the packet duplication. It is assumed inFIG.7that only the CG720of the first cell710is used for the packet transmission, and the CG760of the second cell750is not used for the packet transmission. That is, it may be assumed that the packet duplicate transmission is not activated. In this case, since the RLC entity for using the CG760of the second cell750does not transmit an RLC PDU (corresponding to a MAC SDU) to an MAC entity, the MAC PDU to be transmitted by the CG760of the second cell750is not generated. Thus, the CG760of the second cell750is not used.

If the MAC PDU transmission with the CG720of the first cell710is not successful, the base station may transmit the DFI-NACK721for the transmission of the CG720to the terminal. If the terminal receives the DFI-NACK of the CG resource, this may indicate that the base station does not successfully receive the CG transmission. As such, if the terminal receives the DFI-NACK, the packet duplicate transmission to the configured RLC entity may be activated. As such, a state which the packet duplicate transmission is activated may be referred to as an ST-state722. At this time, the ST indicates the time for surviving from packet loss. If the ST expires and the packet loss is not restored, application layer service requirements may not be satisfied. Hence, the ST-state may require higher reliability transmission.

It has been illustrated in the embodiment ofFIG.7that, if the terminal receives the DFI-NACK, the ST-state is entered and the packet duplicate transmission is activated using the configured RLC entity. Since the packet duplicate transmission is activated, the terminal may perform the packet duplicate transmission using both the RLC entity corresponding to the CG730of the first cell710and the RLC entity corresponding to the CG770of the second cell750. That is, the packet duplicate transmission may be performed using the CG730of the first cell710and the CG770of the second cell750. The packet duplicate transmission activation indication or configuration may be forwarded from the MAC entity of the terminal to the PDCP entity which is an upper layer.

In an embodiment, the aforementioned ST-state operations may be performed only at the configured radio bearer. The ST-state operation may be configured by the base station for the terminal with an RRC message.

If the packet duplicate transmission is activated, high reliability may be ensured. However, since the packet duplicate transmission causes considerable radio resource waste, it is necessary to deactivate the packet duplicate transmission in the successful transmission of the ST-state.FIG.7illustrates that the packet duplicate transmission is deactivated by DFI-ACK indicating the successful reception of the CG transmission. The DFI-ACK may be a message used for the base station to notify the terminal of TB transmission success for the uplink grant in the unlicensed band. As aforementioned, since the packet duplicate transmission may degrade the radio resource efficiency, it may be not always advantageous to use the packet duplication. If the terminal receives the DFI-ACK731for the CG resource, this may indicate that the base station successfully receives the CG transmission. If the terminal receives the DFI-ACK731, the packet duplicate transmission to every configured RLC entity may be deactivated. That is, the terminal may terminate the ST-state. In this case, the PDCP entity of the terminal may perform transmission using a primary RLC entity of the configured RLC entities. The transmission is performed using the CG740of the first cell710corresponding to the primary RLC entity. The CG780of the second cell750corresponding to other RLC entity is not used. The packet duplicate transmission deactivation indication or configuration may be forwarded from the MAC entity of the terminal to the PDCP entity which is an upper layer.

FIG.8illustrates an example of a base station structure according to embodiments of the present disclosure.

Referring toFIG.8, the base station of the present disclosure may include a transceiver810, a storage820, and a controller830. The transceiver810, the storage820, and the controller830of the base station may operate depending on the communication method of the base station. Notably, the base station components are not limited to this example. For example, the base station may include more or less components than the components described above.

The transceiver810combines a receiver of the base station and a transmitter of the base station and may transmit and receive a signal to and from the terminal and/or other network entity. The signal transmitted and received to and from the terminal and/or other network entity may include control information and data. For doing so, the transceiver810may include a radio frequency (RF) transmitter for up-converting and amplifying a frequency of the transmitted signal, an RF receiver for low noise amplifying the received signal and down-converting the frequency, and so on. Notably, this is merely an embodiment of the transceiver810, and the components of the transceiver810are not limited to the RF transmitter and the RF receiver. Also, the transceiver810may include various configurations for transmitting and receiving a signal. In addition, the transceiver810may receive a signal over a wired or wireless channel and output the signal to the controller830, and transmit a signal outputted from the controller830over the wired or wireless channel.

The storage820may store a program and data required to operate the base station. In addition, the storage820may store the control information or the data included in the signal obtained at the base station. The storage820may include a storage medium such as a read only memory (ROM), a random access memory (RAM), a hard disk, a compact disc (CD)-ROM and a digital versatile disc (DVD), or a combination thereof.

The controller830may control a series of processes to operate the base station according to embodiments of the present disclosure. The controller830may include at least one or more processors.

FIG.9illustrates an example of a terminal structure according to embodiments of the present disclosure.

Referring toFIG.9, the terminal of the present disclosure may include a transceiver910, a storage920, and a controller930. The transceiver910, the storage920, and the controller930of the terminal may operate depending on the communication method of the terminal. Notably, the terminal components are not limited to this example. For example, the terminal may include more or less components than the components described above. Besides, the transceiver910, the storage920, and the controller930may be implemented as one chip.

The transceiver910combines a receiver of the terminal and a transmitter of the terminal and may transmit and receive a signal to and from the base station and/or a network entity. The signal transmitted and received to and from the base station may include control information and data. For doing so, the transceiver910may include an RF transmitter for up-converting and amplifying a frequency of the transmitted signal, an RF receiver for low noise amplifying the received signal and down-converting the frequency, and so on. Notably, this is merely an embodiment of the transceiver910, and the components of the transceiver910are not limited to the RF transmitter and the RF receiver. Also, the transceiver910may include various configurations for transmitting and receiving a signal. In addition, the transceiver910may receive a signal over a wireless channel and output the signal to the controller930, and transmit a signal outputted from the controller930over the wireless channel.

In addition, the transceiver910may receive and output a communication signal to the controller930, and transmit a signal outputted from the controller930to the network entity over the wired or wireless channel.

The storage920may store a program and data required to operate the terminal. In addition, the storage920may store the control information or the data included in the signal obtained at the terminal. The storage920may include a storage medium such as a ROM, a RAM, a hard disk, a CD-ROM and a DVD, or a combination thereof.

The controller930may control a series of processes to operate the terminal according to embodiments of the present disclosure. The controller930may include at least one or more processors. For example, the controller930may include a communication processor (CP) for controlling the communication and an application processor (AP) for controlling the upper layer such as an application program.

The methods according to the embodiments described in the claims or the specification of the present disclosure may be implemented in software, hardware, or a combination of hardware and software.

As for the software, a computer-readable storage medium storing one or more programs (software modules) may be provided. One or more programs stored in the computer-readable storage medium may be configured for execution by one or more processors of an electronic device. One or more programs may include instructions for controlling an electronic device to execute the methods according to the embodiments described in the claims or the specification of the present disclosure.

Such a program (software module, software) may be stored to a random access memory, a non-volatile memory including a flash memory, a ROM, an electrically erasable programmable ROM (EEPROM), a magnetic disc storage device, a CD-ROM, DVDs or other optical storage devices, and a magnetic cassette. Alternatively, it may be stored to a memory combining part or all of those recording media. A plurality of memories may be included.

Also, the program may be stored in an attachable storage device accessible via a communication network such as internet, intranet, local area network (LAN), wide LAN (WLAN), or storage area network (SAN), or a communication network by combining these networks. Such a storage device may access a device which executes an embodiment of the present disclosure through an external port. In addition, a separate storage device on the communication network may access the device which executes an embodiment of the present disclosure.

In the embodiments of the present disclosure, the components included in the present disclosure are expressed in a singular or plural form. However, the singular or plural expression is appropriately selected according to a provided situation for the convenience of explanation, the present disclosure is not limited to a single component or a plurality of components, the components expressed in the plural form may be configured as a single component, and the components expressed in the singular form may be configured as a plurality of components.

In the drawings for explaining the method of the present disclosure, the order of description does not necessarily correspond to the execution order, and the precedence relationship may be changed or may be executed in parallel. Also, the drawings explaining the method of the present disclosure may omit some component and include only some element therein without departing from the essential spirit and the scope of the present disclosure.

The embodiments of the present disclosure may be fulfilled by combining some or all of the contents of each embodiment without departing from the essential spirit and the scope of the present disclosure.

Meanwhile, the embodiments of the present disclosure shown in the specification and the drawings present merely specific examples to easily explain the technical contents of the present disclosure and help understanding of the present disclosure, and are not intended to limit the scope of the present disclosure. That is, it will be apparent to those skilled in the art that other variants based on the technical idea of the disclosure than the disclosed embodiments may be implemented.