WO2022191481A1

WO2022191481A1 - Method and system to handle radio link failure in a wireless communication network

Info

Publication number: WO2022191481A1
Application number: PCT/KR2022/002793
Authority: WO
Inventors: Neha Sharma; Aneesh Deshmukh; Nayan OSTWAL
Original assignee: Samsung Electronics Co., Ltd.
Priority date: 2021-03-09
Filing date: 2022-02-25
Publication date: 2022-09-15

Abstract

The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. The present disclosure relates to method and system to handle radio link failure in a wireless communication network. The method comprises detecting a transmission error in at least one Radio Link Control (RLC) sub-flow among a plurality of RLC sub-flows and deactivating the at least one detected RLC sub-flow. The method comprises performing one or more control measures based on the deactivation of the at least one detected RLC sub-flow.

Description

METHOD AND SYSTEM TO HANDLE RADIO LINK FAILURE IN A WIRELESS COMMUNICATION NETWORK

The present disclosure relates to a method and a system for wireless communication, in particular, relates to method and system to handle radio link failure for 6^th Generation (6G) or Beyond 5^th Generation (B5G) system.

5G mobile communication technologies define broad frequency bands such that high transmission rates and new services are possible, and can be implemented not only in "Sub 6GHz" bands such as 3.5GHz, but also in "Above 6GHz" bands referred to as mmWave including 28GHz and 39GHz. In addition, it has been considered to implement 6G mobile communication technologies (referred to as Beyond 5G systems) in terahertz bands (for example, 95GHz to 3THz bands) in order to accomplish transmission rates fifty times faster than 5G mobile communication technologies and ultra-low latencies one-tenth of 5G mobile communication technologies.

At the beginning of the development of 5G mobile communication technologies, in order to support services and to satisfy performance requirements in connection with enhanced Mobile BroadBand (eMBB), Ultra Reliable Low Latency Communications (URLLC), and massive Machine-Type Communications (mMTC), there has been ongoing standardization regarding beamforming and massive MIMO for mitigating radio-wave path loss and increasing radio-wave transmission distances in mmWave, supporting numerologies (for example, operating multiple subcarrier spacings) for efficiently utilizing mmWave resources and dynamic operation of slot formats, initial access technologies for supporting multi-beam transmission and broadbands, definition and operation of BWP (BandWidth Part), new channel coding methods such as a LDPC (Low Density Parity Check) code for large amount of data transmission and a polar code for highly reliable transmission of control information, L2 pre-processing, and network slicing for providing a dedicated network specialized to a specific service.

Currently, there are ongoing discussions regarding improvement and performance enhancement of initial 5G mobile communication technologies in view of services to be supported by 5G mobile communication technologies, and there has been physical layer standardization regarding technologies such as V2X (Vehicle-to-everything) for aiding driving determination by autonomous vehicles based on information regarding positions and states of vehicles transmitted by the vehicles and for enhancing user convenience, NR-U (New Radio Unlicensed) aimed at system operations conforming to various regulation-related requirements in unlicensed bands, NR UE Power Saving, Non-Terrestrial Network (NTN) which is UE-satellite direct communication for providing coverage in an area in which communication with terrestrial networks is unavailable, and positioning.

Moreover, there has been ongoing standardization in air interface architecture/protocol regarding technologies such as Industrial Internet of Things (IIoT) for supporting new services through interworking and convergence with other industries, IAB (Integrated Access and Backhaul) for providing a node for network service area expansion by supporting a wireless backhaul link and an access link in an integrated manner, mobility enhancement including conditional handover and DAPS (Dual Active Protocol Stack) handover, and two-step random access for simplifying random access procedures (2-step RACH for NR). There also has been ongoing standardization in system architecture/service regarding a 5G baseline architecture (for example, service based architecture or service based interface) for combining Network Functions Virtualization (NFV) and Software-Defined Networking (SDN) technologies, and Mobile Edge Computing (MEC) for receiving services based on UE positions.

As 5G mobile communication systems are commercialized, connected devices that have been exponentially increasing will be connected to communication networks, and it is accordingly expected that enhanced functions and performances of 5G mobile communication systems and integrated operations of connected devices will be necessary. To this end, new research is scheduled in connection with eXtended Reality (XR) for efficiently supporting AR (Augmented Reality), VR (Virtual Reality), MR (Mixed Reality) and the like, 5G performance improvement and complexity reduction by utilizing Artificial Intelligence (AI) and Machine Learning (ML), AI service support, metaverse service support, and drone communication.

Furthermore, such development of 5G mobile communication systems will serve as a basis for developing not only new waveforms for providing coverage in terahertz bands of 6G mobile communication technologies, multi-antenna transmission technologies such as Full Dimensional MIMO (FD-MIMO), array antennas and large-scale antennas, metamaterial-based lenses and antennas for improving coverage of terahertz band signals, high-dimensional space multiplexing technology using OAM (Orbital Angular Momentum), and RIS (Reconfigurable Intelligent Surface), but also full-duplex technology for increasing frequency efficiency of 6G mobile communication technologies and improving system networks, AI-based communication technology for implementing system optimization by utilizing satellites and AI (Artificial Intelligence) from the design stage and internalizing end-to-end AI support functions, and next-generation distributed computing technology for implementing services at levels of complexity exceeding the limit of UE operation capability by utilizing ultra-high-performance communication and computing resources.

Existing fifth generation (5G) of the wireless technology or New Radio (NR) as officially named by the 3GPP (Third Generation Partnership Project) is able to support or claim to support a few Gigabits per second (Gbps) of data per user in good channel conditions. A typical Radio Access Network (RAN) entity supporting 5G also supports data up to 10s of Gbps. However, as the technology evolves for exploring higher frequency bands, efficient spectrum utilization and need for advanced use cases demanding high throughput, the demand for throughput is going to increase continuously.

The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the disclosure and should not be taken as an acknowledgement or any form of suggestion that this information forms prior art already known to a person skilled in the art.

In general, with the advancement in the field of wireless communication systems, requirement of peak data rate throughput in future wireless communication systems may go easily beyond 100Gbps. One of the techniques to achieve enormously high data rate throughput is parallelizing Radio Link Control (RLC) with data decomposition.

In order to implement parallelization of RLC, at the transmitter, a transport layer is mapped to one radio flow at PDCP layer. Further, the PDCP layer is mapped to multiple RLC sub-flows through functionality referred to as a distributor at the PDCP layer. Each RLC sub-flow of the RLC functionality is performed independently on different threads either on same or logical cores for the said sub-flows, wherein there is no inter-dependency of the RLC functionality among the sub-flows. The MAC layer, connected to the multiple RLC sub-flows, multiplexes data packets from one or more RLC sub-flows into one MAC data packet or multiple MAC data packets based on the number of frequency carrier components it is operating upon and delivers the multiplexed data packets to respective physical (PHY) layer for transmission.

Among these multiple RLC sub-flows, any particular RLC sub-flow can have issue like maximum number of retransmissions (or) any other RLC failure. All of these RLC sub-flows have their independent state variables and transmit data based on distribution mechanism at the PDCP layer. As per current art if any such issue occurs, it leads to re-establishment procedure which can cause interruption in ongoing service. In this case, if issue occurs on single RLC sub-flow, whole bearer services will be suspended which impacts ongoing user experience. Thus, there is a need for an efficient method and system to handle radio link failure for 6th Generation (6G) or Beyond 5th Generation (B5G) system.

Embodiments of the present disclosure relate to a method performed by a user equipment (UE) in a wireless communication network. The method comprising detecting a transmission error in at least one Radio Link Control (RLC) sub-flow among a plurality of RLC sub-flows and deactivating the at least one detected RLC sub-flow. The method also comprising performing one or more control measures based on the deactivation of the at least one detected RLC sub-flow.

Another aspect of the present disclosure relates to an apparatus in a wireless communication network. The apparatus comprises a processor, wherein the processor is configured to detect a transmission error in at least one Radio Link Control (RLC) sub-flow among a plurality of RLC sub-flows. The processor is also configured to deactivate the at least one detected RLC sub-flow and perform one or more control measures based on the deactivation of the at least one detected RLC sub-flow.

The aforementioned aspects of the present disclosure may overcome one or more of the shortcomings of the prior art. Additional features and advantages may be realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

Present disclosure provides method and system to handle radio link failure. By using the proposed method to handle radio link failure the ongoing experience of the user accessing the user equipment will not be hampered. By providing continuous data communication through existing available RLC sub-flows, data continuity will not be lost and it will be ensured that disruption in service is not experienced by the user.

These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

The disclosure is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:

Figure 1 shows a wireless communication system including a plurality of User Equipment's (UE's) and a network entity, in accordance with an embodiment of the present disclosure;

Figure 2 is a functional block diagram of the UE and the network of the wireless communication system shown in Figure 1, in accordance with an embodiment of the present disclosure;

Figure 3 illustrates a flowchart representing the steps involved in a method for error handling in radio link layer, in accordance with an embodiment of the present disclosure; and

Figure 4 illustrates an example diagram of data processing in the UE having multiple RLC sub-flows, in accordance with an embodiment of the present disclosure.

The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. The term "or" as used herein, refers to a non-exclusive or, unless otherwise indicated. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those skilled in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

As is traditional in the field, embodiments may be described and illustrated in terms of blocks which carry out a described function or functions. These blocks, which may be referred to herein as managers, units, modules, hardware components or the like, are physically implemented by analog and/or digital circuits such as logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, hardwired circuits and the like, and may optionally be driven by firmware. The circuits may, for example, be embodied in one or more semiconductor chips, or on substrate supports such as printed circuit boards and the like. The circuits constituting a block may be implemented by dedicated hardware, or by a processor (e.g., one or more programmed microprocessors and associated circuitry), or by a combination of dedicated hardware to perform some functions of the block and a processor to perform other functions of the block. Each block of the embodiments may be physically separated into two or more interacting and discrete blocks without departing from the scope of the disclosure. Likewise, the blocks of the embodiments may be physically combined into more complex blocks without departing from the scope of the disclosure.

In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or implementation of the present subject matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the drawings and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the disclosure.

The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or device or method. In other words, one or more elements in a device or system or apparatus proceeded by "comprises...a" does not, without more constraints, preclude the existence of other elements or additional elements in the device or system or apparatus.

In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.

Figure 1 shows a wireless communication system 100 including a plurality of User Equipments (UE's) and a network entity, in accordance with an embodiment of the present disclosure.

As shown in figure 1, the plurality of UEs 110 to 140 is in communication with the network entity 150. In one embodiment, the network entity 150 is also known as a base station. Although four UEs 110 to 140 and the network entity 150 are shown in fig. 1, it should be noted that any number of such wireless devices may be included in the wireless communication system 100. Examples of the UE 110 to 140 includes, but are not limited to a smart phone, a tablet computer, a Personal Digital Assistance (PDA), a desktop computer, an Internet of Things (IoT), a wearable device, a Customer Premise Equipment (CPE), etc. The present disclosure relates to an efficient method to handle radio link failure for 6th Generation (6G) or Beyond 5th Generation (B5G) system, to perform modifications to RLC layer in the UEs 110 to 140, which will be explained in the forthcoming paragraphs.

Figure 2 is a functional block diagram 200 of the UE and the network of the wireless communication system shown in fig. 1, in accordance with an embodiment of the present disclosure.

As shown in figure 2, the UE 110 is in communication with the network entity 150. In addition to the components that may be found in a typical UE, the UE 110 includes a memory 201, a processor 202, a receiver 204, a transmitter 206, and an antenna 208. The processor 202, which is coupled to the memory 201, is configured to perform the methods disclosed herein for handling radio link failure in UE 110, in conjunction with one or modules such as a detection module 210, a deactivation module 212, a control module 214, a reporting module 216, and a transmission module 218. The receiver 204 and the transmitter 206 are in communication with the processor 202 and are configured to receive and transmit data from/to the network entity 150.

The memory 201 is configured to store one or more Packet Data Units (PDUs), wherein the PDU includes information that need to be transmitted to another UE via the network entity 150. The memory 201 may include non-volatile storage elements. Examples of such non-volatile storage elements may include magnetic hard discs, optical discs, floppy discs, flash memories, or forms of an Electrically Programmable Memory (EPROM) or an Electrically Erasable and Programmable Memory (EEPROM). In addition, the memory 201 may, in some examples, be considered a non-transitory storage medium. The term "non-transitory" may indicate that the storage medium is not embodied in a carrier wave or a propagated signal. However, the term 'non-transitory' should not be interpreted that the memory 201 is non-movable. In some examples, the memory 201 can be configured to store larger amounts of information than the memory 201 respectively. In certain examples, a non-transitory storage medium may store data that can, over time, change (e.g., in Random Access Memory (RAM) or cache).

The processor 202 is configured to handle radio link failure in the UE 110. The processor 202 may be a general-purpose processor, such as a Central Processing Unit (CPU), an Application Processor (AP), or the like, a graphics-only processing unit such as a Graphics Processing Unit (GPU), a Visual Processing Unit (VPU) and the like. The processor 202 may include multiple cores to execute the instructions.

When a user associated with the UE 110 transmits data to any another UE such as UE 120, 130, or 140, the data is stored as the PDUs in the memory 201.

In one embodiment, the processor 202 is configured to receive the PDUs from the memory 201. The processor 202 is configured to distribute the PDUs to the data link layers of the UE 110 for parallel processing of the PDUs. The UE 110 is configured to send the processed PDUs (i.e., Service Data Units (SDUs)) using one or more RLC sub-flows to the network entity 150.

The detection module 210 is configured to detect the transmission error in at least one Radio Link Control (RLC) sub-flow among a plurality of RLC sub-flows if any RLC sub-flow is unable to send data packets assigned to that particular RLC sub-flow. In order to detect the transmission error, the detection module 210 is configured to transmit at least one RLC packet using the at least one RLC sub-flow and receive an indication that the at least one RLC packet is unsuccessfully transmitted. In order to detect the transmission error, the detection module 210 is further configured to determine a number of times that the at least one RLC packet is unsuccessfully retransmitted after the indication is received and detect the transmission error in the at least one RLC sub-flow when the determined number is greater than the maximum number of re-transmission.

The deactivation module 212, is coupled to the detection module 210, and is configured to deactivate the at least one detected RLC sub-flow having the transmission error. The deactivation module 212 is configured to deactivate the at least one detected RLC sub-flow by temporarily suspending the at least one detected RLC sub-flow. In one example, for the UE 110 having 6 RLC sub-flows and having a transmission error in a first RLC sub-flow, the deactivation module 212 is configured to temporarily suspend the first RLC sub-flow, thereby avoiding the transmission of data packets through RLC sub-flow having one or more issues.

The control module 214, is coupled to the deactivation module 212, and is configured to perform one or more control measures based on the deactivation of the at least one detected RLC sub-flow having transmission error. The control module 214 is configured to perform one or more control measures by at least one of deleting a RLC Service Data Unit (SDU), and one or more RLC SDU segments associated with the at least one RLC sub-flow, resetting at least one timer associated with the at least one RLC sub-flow, and resetting one or more state variables associated with the at least one RLC sub-flow to initial values. In one embodiment, the at least one timer can be t-Reassembly, t-StatusProhibit, and t-pollRetransmit timer. In another embodiment, the one or more state variables can be TX_NEXT, TX_NEXT_HIGHEST, RX_NEXT, and RX_NEXT_HIGHEST.

The reporting module 216, is coupled to at least one of the deactivation module 212 and the control module 214, and is configured to report the transmission error to the network entity 150 such as base station. In one embodiment, the reporting module 216 is configured to report the transmission error to the network entity 150 after performing the one or more control measures.

In another embodiment, the reporting module 216 is configured to report the transmission error to the network entity 150 when the one or more control measures are performed. In an exemplary embodiment, the reporting module 216 is configured to report the transmission error using at least one of Radio Resource Control (RRC) messages and Layer2 messages using PDCP layer, RLC layer, MAC layer, or L1 layer.

The transmission module 218, is coupled to the detection module 210, and is configured to transmit at least one RLC packet associated with the at least one detected RLC sub-flow through another sub-flow, after performing the one or more control measures using a Packet Data Convergence Protocol (PDCP) layer.

Further, in one embodiment, the transmission module 218 is configured to transmit a Buffer Status Report (BSR) from the PDCP layer to a Media Access Control (MAC) layer, wherein the PDCP layer is associated with the plurality of RLC sub-flows.

Further, in another embodiment, the transmission module 218 is configured to transmit a Buffer Status Report (BSR) from the primary RLC sub-flow to a Media Access Control (MAC) layer associated with a primary RLC sub-flow, when the plurality of RLC sub-flows includes a primary RLC sub-flow and information about the primary RLC sub-flow is received from the network entity 150.

As shown in figure 2, in addition to the components that may be found in a typical network entity, the network entity 150 includes a memory 251, a processor 252, a receiver 254, a transmitter 256, and an antenna 258. The processor 252, which is coupled to the memory 251, is configured to enable the UE 110 to handle radio link failure in UE 110. The receiver 204 and the transmitter 206 are in communication with the processor 202 and are configured to receive and transmit data from/to the network entity 150.

The memory 251 is configured to store one or more Packet Data Units (PDUs), wherein the PDU includes information that need to be transmitted to another UE which is transmitted by the UE 110. The memory 251 may include non-volatile storage elements. Examples of such non-volatile storage elements may include magnetic hard discs, optical discs, floppy discs, flash memories, or forms of an electrically programmable memory (EPROM) or an electrically erasable and programmable memory (EEPROM). In addition, the memory 251 may, in some examples, be considered a non-transitory storage medium. The term "non-transitory" may indicate that the storage medium is not embodied in a carrier wave or a propagated signal. However, the term 'non-transitory' should not be interpreted that the memory 251 is non-movable. In some examples, the memory 251 can be configured to store larger amounts of information than the memory 251 respectively. In certain examples, a non-transitory storage medium may store data that can, over time, change (e.g., in random access memory (RAM) or cache).

The processor 252 may be a general-purpose processor, such as a central processing unit (CPU), an application processor (AP), or the like, a graphics-only processing unit such as a graphics processing unit (GPU), a visual processing Unit (VPU) and the like. The processor 252 may include multiple cores to execute the instructions.

Figure 3 illustrates a flowchart representing the steps involved in a method for error handling in a radio link layer, in accordance with an embodiment of the present disclosure.

As illustrated in Figure 3, the flowchart 300 comprises one or more steps or blocks performed by UE 110 in accordance with an embodiment of the present disclosure.

The order in which the method 300 is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method. Additionally, individual blocks may be deleted from the methods without departing from the spirit and scope of the subject matter described herein. Furthermore, the method can be implemented in any suitable hardware, software, firmware, or combination thereof.

The method 300 includes detecting a transmission error in at least one Radio Link Control (RLC) sub-flow among a plurality of RLC sub-flows, in step 302. In one embodiment, the detection module 210 is configured to detect the transmission error in at least one Radio Link Control (RLC) sub-flow among a plurality of RLC sub-flows. In order to detect the transmission error, the detection module 210 is configured to transmit at least one RLC packet using the at least one RLC sub-flow and receive an indication that the at least one RLC packet is unsuccessfully transmitted. In order to detect the transmission error, the detection module 210 is further configured to determine a number of times that the at least one RLC packet is unsuccessfully retransmitted after the indication is received and detect the transmission error in the at least one RLC sub-flow when the determined number is greater than the maximum number of re-transmission. For example, if RLC MaxRetransmission for a given RLC sub-flow is configured to be 16, then if the number of attempts to recover one particular packet of RLC i.e. corresponding to one RLC Sequence Number (Sequence Number) reaches the configured MaxRetransmission value, then this RLC sub-flow can declare Radio Link Failure (RLF) scenario.

The method 300 includes deactivating the at least one detected RLC sub-flow, in step 304. In one embodiment, the deactivation module 210 is configured to deactivate the at least one detected RLC sub-flow having the transmission error. The deactivation module 210 is configured to deactivate the at least one detected RLC sub-flow by temporarily suspending the at least one detected RLC sub-flow. In one example, for the UE 110 having 6 RLC sub-flows and having a transmission error in a first RLC sub-flow, the deactivation module 210 is configured to temporarily suspend the first RLC sub-flow, thereby avoiding the transmission of data packets through RLC sub-flow having one or more issues.

The method 300 includes performing one or more control measures based on the deactivation of the at least one detected RLC sub-flow, in step 306. In one embodiment, the control module 214 is configured to perform one or more control measures based on the deactivation of the at least one detected RLC sub-flow having transmission error. The control module 214 is configured to perform one or more control measures by at least one of deleting a RLC Service Data Unit (SDU), and one or more RLC SDU segments associated with the at least one RLC sub-flow, resetting at least one timer associated with the at least one RLC sub-flow, and resetting one or more state variables associated with the at least one RLC sub-flow to initial values. In an embodiment, the at least one timer can be t-Reassembly, t-StatusProhibit, and t-pollRetransmit timer. In an embodiment, the one or more state variables can be TX_NEXT, TX_NEXT_HIGHEST, RX_NEXT, and RX_NEXT_HIGHEST.

In an embodiment, after performing the one or more control measures, the reporting module 216 is configured to report the transmission error to the network entity 150 such as base station.

In an embodiment, when the one or more control measures are performed, the reporting module 216 is configured to report the transmission error to the network entity 150. The reporting module 216 is configured to report the transmission error using at least one of Radio Resource Control (RRC) messages and Layer2 messages using PDCP layer, RLC layer, MAC layer, or L1 layer.

After performing the one or more control measures, the transmission module 218 is configured to transmit at least one RLC packet associated with the at least one detected RLC sub-flow through another sub-flow using a Packet Data Convergence Protocol (PDCP) layer. In doing so, the PDCP layer can send data on any of the existing RLC sub-flow which are already existing or any primary RLC sub-flow as well if configured.

Further, in another embodiment, the transmission module 218 is configured to transmit a Buffer Status Report (BSR) from the primary RLC sub-flow to a Media Access Control (MAC) layer associated with a primary RLC sub-flow, when the plurality of RLC sub-flows includes a primary RLC sub-flow and information about the primary RLC sub-flow is received from the network entity.

Figure 4 illustrates an example diagram of the data processing in a user equipment having multiple RLC sub-flows, in accordance with an embodiment of the present disclosure.

When a user associated with the UE 110 transmits data (either via mobile call or message) to any another UE such as UE 120, 130, or 140, the data is received in the IP PDU layer 410. From the IP PDU layer 410, the data is transmitted to the PDCP layer 420. The PDCP layer 420 includes a module known as PDCP Distributor 425, which performs parallel processing of received data to multiple RLC sub-flows (such as RLC sub-flow1 431, RLC sub-flow2 432, .... RLC sub-flow6 436).

If RLC sub-flow 1 431 is unable to send data packets assigned to that particular RLC sub-flow, the detection module 210 of the UE 110 is configured to detect the transmission error in the Radio Link Control (RLC) sub-flow 1 431 among a plurality of RLC sub-flows when the determined number of times data packet retransmitted is greater than the maximum number of re-transmission.

The deactivation module 212, is coupled to the detection module 210, and is configured to deactivate the RLC sub-flow 1 431 having the transmission error by temporarily suspending the detected RLC sub-flow 1 431, thereby avoiding the transmission of data packets through the detected RLC sub-flow 1 431 having one or more issues.

The control module 214, is coupled to the deactivation module 212, and is configured to perform one or more control measures based on the deactivation of the detected RLC sub-flow 1 having transmission error. The control module 214 is configured to perform one or more control measures by at least one of deleting a RLC Service Data Unit (SDU), and one or more RLC SDU segments associated with the RLC sub-flow 1, resetting at least one timer associated with the RLC sub-flow 1, and resetting one or more state variables associated with the RLC sub-flow 1 to initial values.

The transmission module 218, is coupled to the detection module 210, and is configured to transmit one or more RLC packet associated with the detected RLC sub-flow 1 through a second RLC sub-flow (as indicated by the dotted lines) using the PDCP layer.

By using the proposed method to handle radio link failure, the ongoing experience of the user accessing the user equipment will not be hampered. By providing continuous data communication through existing available RLC sub-flows, data continuity will not be lost and it will be ensured that disruption in service is not experienced by the user.

Finally, the language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. Accordingly, the disclosure of the embodiments of the disclosure is intended to be illustrative, but not limiting, of the scope of the disclosure.

With respect to the use of substantially any plural and/or singular terms herein, those having skill in the art can translate from the plural to the singular and/or from the singular to the plural as is appropriate to the context and/or application. The various singular/plural permutations may be expressly set forth herein for sake of clarity.

Claims

A method performed by a user equipment (UE) in a wireless communication network, the method comprising:

detecting a transmission error in at least one Radio Link Control (RLC) sub-flow among a plurality of RLC sub-flows;

deactivating the at least one detected RLC sub-flow; and

performing one or more control measures based on the deactivation of the at least one detected RLC sub-flow.
The method of claim 1, further comprising:

reporting the transmission error to a network entity, wherein the transmission error is reported using at least one of Radio Resource Control (RRC) messages and Layer 2 messages.
The method of claim 1, wherein detecting the transmission error comprises:

transmitting at least one RLC packet using the at least one RLC sub-flow;

receiving an indication that the at least one RLC packet is unsuccessfully transmitted;

determining a number of times that the at least one RLC packet is unsuccessfully retransmitted after the indication is received; and

detecting the transmission error in the at least one RLC sub-flow when the determined number is greater than the maximum number of re-transmission.
The method of claim 1, wherein deactivating the detected at least one RLC sub-flow comprises temporarily suspending the at least one detected RLC sub-flow.
The method of claim 1, wherein performing the one or more control measures comprises at least one of:

deleting a RLC Service Data Unit (SDU), and one or more RLC SDU segments associated with the at least one RLC sub-flow;

resetting at least one timer associated with the at least one RLC sub-flow; and

resetting one or more state variables associated with the at least one RLC sub-flow to initial values.
The method of claim 1, further comprising transmitting at least one RLC packet of the at least one detected RLC sub-flow through another RLC sub-flow, upon detecting the transmission error.
The method of claim 5, wherein the at least one timer includes at least one of t-Reassembly, t-StatusProhibit, and t-pollRetransmit timer, and

wherein the one or more state variables include at least one of TX_NEXT, TX_NEXT_HIGHEST, RX_NEXT, and RX_NEXT_HIGHEST.
The method of claim 1, further comprising:

transmitting a Buffer Status Report (BSR) from a Packet Data Convergence Protocol (PDCP) layer to a Media Access Control (MAC) layer, wherein the PDCP layer is associated with the plurality of RLC sub-flow.
The method of claim 1, wherein the plurality of RLC sub-flows includes a primary RLC sub-flow, wherein information about the primary RLC sub-flow is received from a network entity, and further comprising:

transmitting a Buffer Status Report (BSR) from the primary RLC sub-flow to a Media Access Control (MAC) layer associated with the primary RLC sub-flow.
An apparatus in a wireless communication network, the apparatus comprises:

a processor configured to:

detect a transmission error in at least one Radio Link Control (RLC) sub-flow among a plurality of RLC sub-flows;

deactivate the at least one detected RLC sub-flow; and

perform one or more control measures based on the deactivation of the at least one detected RLC sub-flow.
The apparatus of claim 10, wherein the processor is further configured to:

report the transmission error to a network entity, wherein the transmission error is reported using at least one of Radio Resource Control (RRC) messages and Layer 2 messages.
The apparatus of claim 10, wherein to detect the transmission error, the processor is configured to:

transmit at least one RLC packet using the at least one RLC sub-flow;

receive an indication that the at least one RLC packet is unsuccessfully transmitted;

determine a number of times that the at least one RLC packet is unsuccessfully retransmitted after the indication is received; and

detect the transmission error in the at least one RLC sub-flow when the determined number is greater than the maximum number of re-transmission.
The apparatus of claim 10, wherein to deactivate the detected at least one RLC sub-flow, the processor is configured to temporarily suspending the at least one detected RLC sub-flow.
The apparatus of claim 10, wherein to perform the one or more control measures, the processor is configured to perform at least one of:

delete a RLC Service Data Unit (SDU), and one or more RLC SDU segments associated with the at least one RLC sub-flow;

reset at least one timer associated with the at least one RLC sub-flow; and

reset one or more state variables associated with the at least one RLC sub-flow to initial values,

wherein the at least one timer includes at least one of t-Reassembly, t-StatusProhibit, and t-pollRetransmit timer, and

wherein the one or more state variables include at least one of TX_NEXT, TX_NEXT_HIGHEST, RX_NEXT, and RX_NEXT_HIGHEST.
The apparatus of claim 10, wherein the processor is configured to:

transmit at least one RLC packet of the at least one detected RLC sub-flow through another RLC sub-flow, upon detection of the transmission error, and

transmit a Buffer Status Report (BSR) from a Packet Data Convergence Protocol (PDCP) layer to a Media Access Control (MAC) layer, wherein the PDCP layer is associated with the plurality of RLC sub-flow, wherein the plurality of RLC sub-flows includes a primary RLC sub-flow, wherein information about the primary RLC sub-flow is received from a network entity, and

wherein the processor is configured to:

transmit a Buffer Status Report (BSR) from the primary RLC sub-flow to a Media Access Control (MAC) layer associated with the primary RLC sub-flow.