Methods and apparatus for in-order delivery of packets

Abstract

Methods, apparatus and computer-readable medium are disclosed for configuration information validity. A method for in-order delivery in a transmitting device comprises including into each packet of a sequence of packets, a priority indicator indicating whether respective packets are prioritized packets a missing of which in the in-order delivery is not allowed to be skipped. In case that a packet is a prioritized packet, a priority indicator included in the prioritized packet further indicates a sequence of prioritized packets comprising the prioritized packet. The method comprises transmitting the sequence of packets to a receiving device.

Description

[0001] METHODS AND APPARATUS FOR IN-ORDER DELIVERY OF PACKETS

[0002] TECHNICAL FIELD

[0003] [1] Various example embodiments relate generally to wireless communication technology, and more particularly, to methods and apparatus for in-order delivery of packets in wireless communication.

[0004] BACKGROUND

[0005] [2] In a wireless interface protocol stack, Packet Data Convergence Protocol (PDCP) layer is arranged in a second layer, between Service Data Adaptation Protocol (SDAP) / Radio Resource Control (RRC) layer and Radio Link Control (RLC) layer. The PDCP layer is responsible for transfer of data (user plane or control plane), which can be understood as transmitting operation and receiving operation for PDCP protocol data units (PDUs).

[0006] [3] With regard to the transmitting operation, a PDCP entity at a transmitting end would receive service data units (SDUs) (including user plane data or control plane data) from an upper layer (e.g., SDAP / RRC layer) over the PDCP layer, transform the SDUs (e.g., by header compression and ciphering) to PDUs, and then deliver the PDUs to a lower layer (e.g., RLC layer) under a PDCP layer for transmitting them to a peer PDCP entity at a receiving end. With regard to the receiving operation, a PDCP entity at a receiving end would receive PDUs from the lower layer (such as the RLC layer) which are transmitted from a peer PDCP entity at the transmitting end, transform the PDUs (e.g., by header decompression and de-ciphering) to SDUs, and then deliver the SDUs to an upper layer (e.g., the SDAP / RRC layer).

[0007] [4] The PDCP layer may support reordering and in-order delivery of SDUs. The functionality of this feature requires a PDCP entity at a receiving end to ensure that packets are delivered to an upper layer in-sequence (according to a PDCP sequence number (SN)). A reordering function may be used to provide in-sequence delivery of SDUs, which may involve a temporary buffering of SDUs received out-of-sequence, as well as an operation of a reordering timer. In this scenario, PDCP PDUs cannot be discarded, as a missing of PDUs would trigger a reordering timer of the reordering function. The reordering function may increase an overall end-to-end latency. This is not advantageous for some applications carrying delay sensitive contents. SUMMARY

[0008] [5] This summary is provided to introduce simplified concepts of the present disclosure. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

[0009] [6] According to a first aspect of the disclosure, there is provided an apparatus for inorder delivery in a transmitting device. The apparatus comprises at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to include into each packet of a sequence of packets, a priority indicator indicating whether respective packets are prioritized packets a missing of which in the in-order delivery is not allowed to be skipped. In case that a packet is a prioritized packet, a priority indicator included in the prioritized packet further indicates a sequence of prioritized packets comprising the prioritized packet. The apparatus is further caused to transmit the sequence of packets to a receiving device.

[0010] [7] According to some embodiments, in case that a packet is a prioritized packet, a priority indicator included in the packet may further indicate that the packet is of one of the following types: a beginning prioritized packet, ordered at a beginning of a sequence of prioritized packets, a middle prioritized packet, ordered in the middle of a sequence of prioritized packets, or an end prioritized packet, ordered at an end of a sequence of prioritized packets.

[0011] [8] According to some embodiments, in case that a packet is a prioritized packet, a priority indicator included in the packet may further indicate whether the packet is a single prioritized packet in a sequence of prioritized packets comprising only one prioritized packet.

[0012] [9] According to some embodiments, in case that a packet is not a prioritized packet, a priority indicator included in the packet may further indicate that the packet is a deprioritized packet, a missing of which in the in-order delivery is allowed to be skipped.

[0013]

[0010] According to some embodiments, a priority indicator included in a packet may comprise at least one first bit indicating whether the packet is a prioritized packet or not. According to some embodiments, a priority indicator included in a prioritized packet may further comprise at least two second bits indicating a sequence of prioritized packets comprising the prioritized packet.

[0011] According to some embodiments, a priority indicator may be comprised of at least 3 bits.

[0014]

[0012] According to some embodiments, a priority indicator may be comprised in a header of a packet.

[0015]

[0013] According to some embodiments, the sequence of packets may be a sequence of protocol data units, PDUs, of packet data convergence protocol, PDCP.

[0016]

[0014] According to some embodiments, the transmitting device may be a base station or a user equipment.

[0017]

[0015] According to a second aspect of the disclosure, there is provided an apparatus for in-order delivery in a receiving device. The apparatus comprises at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to try to receive a sequence of packets from a transmitting device. Each packet includes a priority indicator indicating whether respective packets are prioritized packets a missing of which in the in-order delivery is not allowed to be skipped. In case that a packet is a prioritized packet, a priority indicator included in the prioritized packet further indicates a sequence of prioritized packets comprising the prioritized packet. The apparatus is further caused to determine whether a missing of one or more consecutive packets of the sequence of packets is to be skipped, based on respective priority indicators of received packets before and / or after the one or more consecutive packets in the sequence of packets.

[0018]

[0016] According to some embodiments, the apparatus may be caused to determine whether the missing of the one or more packets is to be skipped by determining that the missing of the one or more consecutive packets is to be skipped under any one of one or more conditions comprising at least one of following conditions:

[0019] • the one or more consecutive packets is one packet between two received packets which include priority indicators indicating that the two packets are not prioritized packets,

[0020] • the one or more consecutive packets are after a received packet which includes a priority indicator indicating that the received packet is an end of a sequence of prioritized packets, and before another received packet which includes a priority indicator indicating that the another received packet is in a sequence of prioritized packets comprising only one prioritized packet or is a beginning of a sequence of prioritized packets, • the one or more consecutive packets are after a received packet which includes a priority indicator indicating that the received packet is in a sequence of prioritized packets comprising only one prioritized packet, and before another received packet which includes a priority indicator indicating that the another received packet is a beginning of a sequence of prioritized,

[0021] • the one or more consecutive packets are between two received packets which include priority indicators indicating that each of the two packets is in a sequence of prioritized packets comprising only one prioritized packet,

[0022] • the one or more missing packets are after a received packet which includes a priority indicator indicating that the packet is not a prioritized packet, and before another received packet which includes a priority indicator indicating that the another received packet is in a sequence of prioritized packets comprising only one prioritized packet,

[0023] • the one or more missing packets are after a received packet which includes a priority indicator indicating that the packet is not a prioritized packet, and before another received packet which includes a priority indicator indicating that the another received packet is a beginning of a sequence of prioritized, or

[0024] • the one or more missing packets are after a received packet which includes a priority indicator indicating that the received packet is an end of a sequence of prioritized packets, and before another received packet which includes a priority indicator indicating that the another packet is not a prioritized packet.

[0025]

[0017] According to some embodiments, when the instructions are executed by the at least one processor, the instructions may further cause the apparatus at least to discard the one or more consecutive packets without starting a re-ordering timer.

[0026]

[0018] According to some embodiments, when the instructions are executed by the at least one processor, the instructions may further cause the apparatus at least to determine if a delay to be caused by a re-ordering for the one or more consecutive packets is acceptable; and wait for a receipt of the one or more consecutive packets with starting a re-ordering timer if it is determined that the delay is acceptable, or discard the one or more consecutive packets without starting a re-ordering timer if it is determined that the delay is not acceptable.

[0019] According to some embodiments, the apparatus may be caused to determine whether the missing of the one or more consecutive packets is to be skipped by, determining that the missing of the one or more consecutive packets is not to be skipped under any one of one or more conditions comprising at least one of following conditions,

[0027] • the one or more consecutive packets are before a received packet which includes a priority indicator indicating that the received packet is in the middle or is an end of a sequence of prioritized packets, or

[0028] • the one or more consecutive packets are before a received packet which includes a priority indicator indicating that the received packet is in a sequence of prioritized packets comprising only one prioritized packet or is a beginning of a sequence of prioritized packets, in case that a prioritized packet of an end of a sequence of prioritized packets before the one or more consecutive packets has not been received at the receiving device.

[0029]

[0020] According to some embodiments, when the instructions are executed by the at least one processor, the instructions may further cause the apparatus at least to wait for a receipt of the one or more consecutive packets with starting a re-ordering timer.

[0030]

[0021] According to some embodiments, in case that a packet is a prioritized packet, a priority indicator included in the packet may further indicate that the packet is of one of the following types: a beginning prioritized packet, ordered at a beginning of a sequence of prioritized packets, a middle prioritized packet, ordered in the middle of a sequence of prioritized packets, or an end prioritized packet, ordered at an end of a sequence of prioritized packets.

[0031]

[0022] According to some embodiments, in case that a packet is a prioritized packet, a priority indicator included in the packet may further indicate whether the packet is a single prioritized packet in a sequence of prioritized packets comprising only one prioritized packet.

[0032]

[0023] According to some embodiments, in case that a packet is not a prioritized packet, a priority indicator included in the packet may further indicate that the packet is a deprioritized packet, a missing of which in the in-order delivery is allowed to be skipped.

[0033]

[0024] According to some embodiments, a priority indicator included in a packet may comprise at least one first bit indicating whether the packet is a prioritized packet or not. According to some embodiments, a priority indicator included in a prioritized packet may further comprise at least two second bits indicating a sequence of prioritized packets comprising the prioritized packet.

[0034]

[0025] According to some embodiments, a priority indicator may be comprised of at least 3 bits.

[0035]

[0026] According to some embodiments, a priority indicator may be comprised in a header of a packet.

[0036]

[0027] According to some embodiments, the sequence of packets may be a sequence of protocol data units, PDUs, of packet data convergence protocol, PDCP.

[0037]

[0028] According to some embodiments, the receiving device may be a base station or a user equipment.

[0038]

[0029] According to a third aspect of the disclosure, there is provided a method for inorder delivery in a transmitting device. The method comprises including into each packet of a sequence of packets, a priority indicator indicating whether respective packets are prioritized packets a missing of which in the in-order delivery is not allowed to be skipped. In case that a packet is a prioritized packet, a priority indicator included in the prioritized packet further indicates a sequence of prioritized packets comprising the prioritized packet. The method comprises transmitting the sequence of packets to a receiving device.

[0039]

[0030] According to a fourth aspect of the disclosure, there is provided a method for inorder delivery in a receiving device. The method comprises trying to receive a sequence of packets from a transmitting device. Each packet includes a priority indicator indicating whether respective packets are prioritized packets a missing of which in the in-order delivery is not allowed to be skipped. In case that a packet is a prioritized packet, a priority indicator included in the prioritized packet further indicates a sequence of prioritized packets comprising the prioritized packet. The method further comprises determining whether a missing of one or more consecutive packets of the sequence of packets is to be skipped, based on respective priority indicators of received packets before and / or after the one or more consecutive packets in the sequence of packets.

[0040]

[0031] According to some embodiments, determining whether the missing of the one or more packets is to be skipped may comprise determining that the missing of the one or more consecutive packets is to be skipped under any one of one or more conditions comprising at least one of following conditions: the one or more consecutive packets is one packet between two received packets which include priority indicators indicating that the two packets are not prioritized packets, the one or more consecutive packets are after a received packet which includes a priority indicator indicating that the received packet is an end of a sequence of prioritized packets, and before another received packet which includes a priority indicator indicating that the another received packet is in a sequence of prioritized packets comprising only one prioritized packet or is a beginning of a sequence of prioritized packets, the one or more consecutive packets are after a received packet which includes a priority indicator indicating that the received packet is in a sequence of prioritized packets comprising only one prioritized packet, and before another received packet which includes a priority indicator indicating that the another received packet is a beginning of a sequence of prioritized, the one or more consecutive packets are between two received packets which include priority indicators indicating that each of the two packets is in a sequence of prioritized packets comprising only one prioritized packet, the one or more missing packets are after a received packet which includes a priority indicator indicating that the packet is not a prioritized packet, and before another received packet which includes a priority indicator indicating that the another received packet is in a sequence of prioritized packets comprising only one prioritized packet, the one or more missing packets are after a received packet which includes a priority indicator indicating that the packet is not a prioritized packet, and before another received packet which includes a priority indicator indicating that the another received packet is a beginning of a sequence of prioritized, or the one or more missing packets are after a received packet which includes a priority indicator indicating that the received packet is an end of a sequence of prioritized packets, and before another received packet which includes a priority indicator indicating that the another packet is not a prioritized packet.

[0032] According to some embodiments, the method may further comprise discarding the one or more consecutive packets without starting a re-ordering timer.

[0041]

[0033] According to some embodiments, the method may further comprise determining if a delay to be caused by a re-ordering for the one or more consecutive packets is acceptable; and waiting for a receipt of the one or more consecutive packets with starting a re-ordering timer if it is determined that the delay is acceptable, or discarding the one or more consecutive packets without starting a re-ordering timer if it is determined that the delay is not acceptable.

[0042]

[0034] According to some embodiments, determining whether the missing of the one or more packets is to be skipped may comprise, determining that the missing of the one or more consecutive packets is not to be skipped under any one of one or more conditions comprising at least one of following conditions:

[0043] • the one or more consecutive packets are before a received packet which includes a priority indicator indicating that the received packet is in the middle or is an end of a sequence of prioritized packets, or

[0044] • the one or more consecutive packets are before a received packet which includes a priority indicator indicating that the received packet is in a sequence of prioritized packets comprising only one prioritized packet or is a beginning of a sequence of prioritized packets, in case that a prioritized packet of an end of a sequence of prioritized packets before the one or more consecutive packets has not been received at the receiving device.

[0045]

[0035] According to a fifth aspect of the disclosure, there is provided an apparatus for inorder delivery in a transmitting device. The apparatus comprising means for including into each packet of a sequence of packets, a priority indicator indicating whether respective packets are prioritized packets a missing of which in the in-order delivery is not allowed to be skipped. In case that a packet is a prioritized packet, a priority indicator included in the prioritized packet further indicates a sequence of prioritized packets comprising the prioritized packet. The apparatus further comprising means for transmitting the sequence of packets to a receiving device.

[0046]

[0036] According to a sixth aspect of the disclosure, there is provided an apparatus for in-order delivery in a receiving device. The apparatus comprising means for trying to receive a sequence of packets from a transmitting device. Each packet includes a priority indicator indicating whether respective packets are prioritized packets a missing of which in the in-order delivery is not allowed to be skipped. In case that a packet is a prioritized packet, a priority indicator included in the prioritized packet further indicates a sequence of prioritized packets comprising the prioritized packet. The apparatus further comprising means for determining whether a missing of one or more consecutive packets of the sequence of packets is to be skipped, based on respective priority indicators of received packets before and / or after the one or more consecutive packets in the sequence of packets.

[0047]

[0037] According to a seventh aspect of the disclosure, there is provided a computer- readable medium having computer program codes embodied thereon which, when executed by a processor, cause the processor to perform any of the methods according to the third and fourth aspects of the disclosure.

[0048]

[0038] According to an eighth aspect of the disclosure, there is provided a computer program product comprising computer programs or instructions which, when executed by a processor, cause the processor to perform any of the methods according to the third and fourth aspects of the disclosure.

[0049]

[0039] It is to be understood that the summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

[0050] BRIEF DESCRIPTION OF THE DRAWINGS

[0051]

[0040] Some example embodiments will now be described with reference to the accompanying drawings in which:

[0052]

[0041] FIG. 1 shows an example of a communication network to which examples disclosed herein may be applied;

[0053]

[0042] FIG. 2A illustrates an exemplary format of PDCP PDU according to embodiments of the present disclosure;

[0054]

[0043] FIG. 2B illustrates an exemplary configuration of a priority indicator according to embodiments of the present disclosure;

[0055]

[0044] FIGs. 3A-3E illustrate exemplary procedures of data transfer according to an embodiment of the present disclosure;

[0045] FIGs. 4A-4E illustrate exemplary procedures of data transfer according to an embodiment of the present disclosure;

[0056]

[0046] FIG. 5 is a flow chart depicting a method performed at a transmitting device according to embodiments of the present disclosure;

[0057]

[0047] FIG. 6 is a flow chart depicting a method performed at a receiving device according to embodiments of the present disclosure;

[0058]

[0048] FIG. 7 is a flow chart depicting another method performed at a receiving device according to embodiments of the present disclosure;

[0059]

[0049] FIG. 8 is a flow chart depicting yet another method performed at a receiving device according to embodiments of the present disclosure; and

[0060]

[0050] FIG. 9 is a block diagram showing an apparatus suitable for practicing some embodiments of the disclosure.

[0061] DETAILED DESCRIPTION

[0062]

[0051] The following embodiments are exemplary. Although the specification may refer to “an”, “one”, or “some” embodiment s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Further, when a particular feature, structure, or characteristic is de-scribed in connection of an embodiment, it is within the knowledge of one skilled in the art to apply such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

[0063]

[0052] For the purposes of the present disclosure, the phrases “at least one of A or B”, “at least one of A and B”, and “A and / or B” means (A), (B), or (A and B). For the purposes of the present disclosure, the phrase “A, B, and / or C” means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0064]

[0053] Embodiments described may be implemented in a communication network, such as any of the following radio access technologies (RATs): Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE-Advanced, and enhanced LTE (eLTE), 5G (also called NR), or any future RAT such as 6G.

[0054] In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

[0065]

[0055] As used herein, the term “network device” or “network node” refers to a node in a communication network via which user equipment may access the radio access network and / or which is capable of controlling radio communication and managing radio resources within a cell. The network node or network device may be referred to as a base station (BS), an access point (AP) or an access node. The network device may be, depending on the applied technology, for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio head (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low power node, a non-terrestrial network (NTN) or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth or-bit (GEO) satellite, or an aircraft network device.

[0066]

[0056] Moreover, in connection of split radio access network (RAN), the network device may refer to a centralized unit (CU) of a base station and / or a distributed unit (DU) of a base station. An interface between CU and DU may be referred to as an Fl interface in NR. In the split RAN architecture, node operations may be carried out, at least partly, in the central / centralized unit, CU, (e.g. server, host or node) operationally coupled to the DU, (e.g. a radio head / node). One CU may control one or more DUs, acting at least as transmit / receive (Tx / Rx) nodes. In some embodiments, the DUs may comprise e.g. a radio link control (RLC), medium access control (MAC) layer and a physical (PHY) layer, whereas the CU may comprise the layers above RLC layer, such as a packet data convergence protocol (PDCP) layer, a radio resource control (RRC) and an internet protocol (IP) layers. Other functional splits are possible too. In practice, any processing task may be performed in either the CU or the DU and the boundary where the responsibility is shifted between the CU and the DU may depend on the applied implementation.

[0067]

[0057] The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example, a terminal device may be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), or a Mobile Station (MS). The terminal device may include a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, USB dongles, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless net-works, and the like.

[0068]

[0058] The term “transmission” and / or “reception” may refer to wirelessly transmitting and / or receiving via a wireless propagation channel on radio resources.

[0069]

[0059] As defined herein, a “computer-readable storage medium,” which refers to a non- transitory physical storage medium (e.g., volatile or non-volatile memory device), may be differentiated from a “computer-readable transmission medium,” which refers to an electromagnetic signal. Such a medium may take many forms, including, but not limited to a non-transitory computer-readable storage medium (e.g., non-volatile media, volatile media), and transmission media. Transmission media include, for example, coaxial cables, copper wire, fiber optic cables, and carrier waves that travel through space without wires or cables, such as acoustic waves and electromagnetic waves, including radio, optical and infrared waves. Signals include man-made transient variations in amplitude, frequency, phase, polarization or other physical properties transmitted through the transmission media. Examples of non-transitory computer-readable media include a magnetic computer readable medium (e.g., a floppy disk, hard disk, magnetic tape, any other magnetic medium), an optical computer readable medium (e.g., a compact disc read only memory (CD-ROM), a digital versatile disc (DVD), a Blu-Ray disc, or the like), a random access memory (RAM), a programmable read only memory (PROM), an erasable programmable read only memory (EPROM), a FLASH-EPROM, or any other non- transitory medium from which a computer may read. The term computer-readable storage medium is used herein to refer to any computer-readable medium except transmission media. However, it will be appreciated that where embodiments are described to use a computer-readable storage medium, other types of computer-readable mediums may be substituted for or used in addition to the computer-readable storage medium in alternative embodiments.

[0070]

[0060] FIG. 1 illustrates an example of a communication network to which examples disclosed herein may be applied. The communication network or a cellular communication network may comprise a network node 110 providing one or more cells, such as cell 100, and a network node 112 providing one or more other cells, such as cell 102. Each cell may be, e.g., a macro cell, a micro cell, femto, or a pico cell, for example. The cell may define a coverage area or a service area of the corresponding access node.

[0071]

[0061] The network node 110 may provide a user equipment (UE) 120 (one or more UEs) with wireless access to the communication network. The wireless access may comprise downlink (DL) communication from the network node to the UE 120 and uplink (UL) communication from the UE 120 to the network node. Examples of uplink channels comprise physical uplink control channel (PUCCH) for transmitting control information and physical uplink shared channel (PUSCH) for transmitting data towards the network. Examples of downlink channels comprise physical downlink control channel (PDCCH) for transmitting control information and physical downlink shared channel (PDSCH) for transmitting data towards the user equipment.

[0072]

[0062] There may be a plurality of UEs 120, 122 in the system. Each of them may be served by the same or by different network nodes 110, 112. UE may be configured with dual connectivity (DC), wherein the UE, e.g. UE 120, may be connected to multiple network nodes 110, 112. The UEs 120, 122 may communicate with each other, in case device-to-device (D2D) communication interface is established between them via a so- called sidelink (SL). Such D2D communications may be referred to as machine-to- machine, peer-to-peer (P2P) communications, or vehicle-to-vehicle (V2V), for example.

[0073]

[0063] In the case of multiple network nodes in the communication network, the network nodes may be connected to each other via an interface. LTE specifications call such an interface as X2 interface. An interface between an LTE node and a 5G node, or between two 5G nodes may be called Xn interface.

[0074]

[0064] The network nodes 110 and 112 may be further connected via another interface to a core network 116 of the communication network. The LTE specifications specify the core network as an evolved packet core (EPC), and the core network may comprise e.g. a mobility management entity (MME) and a gateway node. The MME may handle mobility of terminal devices in a tracking area encompassing a plurality of cells and handle signaling connections between the terminal devices and the core network. The gateway node may handle data routing in the core network and to / from the terminal devices. The 5G specifications specify the core network as a 5G core (5GC). The 5G core may comprise e.g. an access and mobility management function (AMF) and a user plane function / gateway (UPF) and other functions. The AMF may handle termination of non- access stratum (NAS) signaling, NAS ciphering and integrity protection, registration management, connection management, mobility management, access authentication and authorization, security context management. The UPF node may support packet routing and forwarding, packet inspection and quality of service (QoS) handling, for example.

[0075]

[0065] As introduced above, when a PDCP entity is configured for in-order delivery, a PDCP PDU which is not received from a lower layer in-sequence according to a PDCP SN cannot be discarded as this would trigger a re-ordering timer. The re-ordering operation would cause a delay to up-layer applications. Some applications carrying delay sensitive content may not benefit from transmitting packets which are delayed (especially, exceeding a delay budget). These applications may benefit from discarding delayed packets and prioritizing newly received subsequent packets.

[0076]

[0066] It is conceived that there may be some instances when in the network, based on the DPI (Deep Packet Inspection) or Al (Artificial Intelligence) / ML (Machine Learning), contents can be learnt so that delay sensitive contents can be identified and prioritized. This would need some packets to be de-prioritized and eventually discarded whose transmission has been attempted or PDCP SN assigned. Prioritized here refers to packets being classified as packets with a higher priority. De-Prioritized here refers to packets being classified as packets with a lower priority. This classification may be done at a base station (such as gNB), for example, based on requirements of traffic / applications associated with respective packets.

[0077]

[0067] For example, for the 3 GPP applications of delay critical (DC)- guaranteed bit rate (GBR), packets which are used for carrying non-complaint traffic can be de-prioritized and delivered in the absence of maximum data burst volume (MDBV) complaint traffic or when air interface load is available. But as soon as a packet for MDBV complaint traffic is received, it needs to be prioritized. This requires PDCP PDUs to be discarded whose transmissions are attempted or when PDCP SN is already assigned.

[0078]

[0068] Extender reality (XR) application is another example. In the context of XR, a set of PDCP PDUs with a higher priority needs to be prioritized. Ongoing PDCP PDUs with a lower priority PDU would be de-prioritized for transmission over the air interface when the packets with the higher priority arrive.

[0079]

[0069] All the above conceiving cannot be achieved currently when in-order delivery is configured at a PDCP layer as this is an important aspect for the application performance. For the de-prioritized traffic, there is currently no mechanism to operate the PDCP layer without re-ordering for in-order delivery. That is, a selective application of PDCP reordering for in-order delivery is currently not possible.

[0080]

[0070] The PDCP layer may support out-of-order delivery of PDCP SDUs. In case that a PDCP entity at a receiving end is configured for out-of-order delivery, a missed PDCP PDU can be discarded. The PDCP entity may deliver PDCP SDUs to an upper layer immediately (e.g., in the order received), and depending on the reception order of PDCP PDUs from a lower layer. This may result in PDCP SDUs being delivered out of sequence. However, performance of applications (e.g., time critical applications) would be impacted if the packets are delivered out of order, if out-of-order delivery is done frequently. Hence in-order delivery is still preferred towards the applications carrying delay sensitive contents.

[0081]

[0071] Here, the order of packets or PDCP PDUs in a sequence is based on sequence numbers (such as PDCP SNs) of respective packets. The sequence numbers are assigned to respective packets at a transmitting end. Early assignment of PDCP SN may be needed as the PDCP layer and lower layers (such as RLC / MAC) could be non-co-1 ocated (for distributed gNB). In 5G, a PDCP layer is hosted at gNB-control unit (CU), and RLC / MAC / L1 layers is hosted at gNB -distributed unit (DU). In this case, the PDCP layer assigns the PDCP SN to the packets and sends to the gNB-DU for transmissions. The gNB-DU buffers the received packets and schedules over air interface accordingly which creates finite delay. Even in 6G, such distributed architectures are being studied for network deployments. Without the early PDCP SN assignments, network processing / computational capabilities would be very challenging and expensive.

[0082]

[0072] Currently, a simultaneous operation of in-order delivery and out-of-order delivery cannot be applied within a PDCP entity. This disclosure is related to PDCP PDU discarding when in-order delivery in PDCP layer is configured. A new scheme is introduced at the PDCP layer to mark the packets to be skipped and continue data transfer with in-order delivery for the other packets. This would avoid a re-ordering delay at a PDCP layer, due to packets discarded at the PDCP layer and help in the delivery of the time critical data on time to the upper layer (e.g., an application layer).

[0083]

[0073] To achieve an in-order delivery for the prioritized PDCP PDU(s) with simultaneous out-of-order delivery of de-prioritized PDCP PDU(s) with in a PDCP entity, a PDCP entity at a transmitting device (e.g., in a gNB for downlink data transfer, or in a UE for uplink data transfer) includes into each PDCP PDU, an indicator indicating a priority of the PDCP PDU. The priority indicates whether a PDCP PDU including the priority is a prioritized PDU (i.e., a PDU with a higher priority), a missing of which in the in-order delivery is not allowed to be skipped. In case that a PDU is a prioritized PDU, the indicator included in the prioritized PDU further indicates a sequence of prioritized PDUs comprising the prioritized PDU. The indicator can be used to control an in-order delivery and an out-of-order delivery as needed. In case that a PDU is a de-prioritized PDU, the priority (i.e., a lower priority) of the PDU indicated by the indicator may indicate that a missing of the PDU in an in-order delivery is allowed to be skipped.

[0084]

[0074] When one or more consecutive PDCP PDUs are missed, i.e., these PDCP PDUs are not received in a sequence according to PDCP SNs, a PDCP entity at a receiving device (e.g., in a UE for downlink data transfer) could determine whether a missing of these PDUs is to be skipped, based on respective indicators of PDUs received before and / or after the one or more missing PDUs in the sequence. In this regard, if it is determined that these PDUs are of a lower priority (such as being de-prioritized PDUs), a missing of these PDUs may be skipped. For example, these missing PDUs may be treated as if they have been successfully received. Then, re-ordering would be avoided for a missing of these PDCP PDUs at the receiving device.

[0085]

[0075] Embodiments of the present disclosure are applicable for data transfer in either uplink direction or downlink direction. For example, for the uplink direction, the transmitting device may be or may be comprised in a terminal device, such as a UE, while the receiving device may be or may be comprised in a network node, such as a base station, e.g., gNB. For the downlink direction, the transmitting device may be or may be comprised in a network node, such as a base station, e.g., gNB, while the receiving device may be or may be comprised in a terminal device, such as a UE.

[0086]

[0076] FIG. 2A and 2B illustrate an exemplary format and configuration of PDCP PDU according to embodiments of the present disclosure. As shown in FIG. 2A, the PDCP PDU format is modified to include a priority indicator for indicating a priority of a PDCP PDU, and a sequence of prioritized PDUs if applicable. In an example, the priority indicator may be included in a header of a PDU, using reserved bits of the header. In another example, the priority indicator may be included in a payload of a PDU. The PDU may be a PDCP data PDU or a PDCP control PDU. The PDU format of FIG. 2 A is for a PDCP PDU with 18-bit SN. It can be appreciated that embodiments of this disclosure can be applied to PDCP PDU with any SN length. For example, the priority indicator may be included in a header of a PDCP PDU with 12-bit SN. A PDCP PDU including a priority indicator proposed in the present disclosure can take any suitable format.

[0077] In an embodiment, the priority indicator may be comprised of 3 bits (denoted as Bit 0, Bit 1, Bit 2, respectively). A first bit (e.g., Bit 0) of the priority indicator may be set to indicate whether the PDCP PDU is a prioritized PDU or not. For example, the first bit may have a bit value of “0” which indicates that the PDU is not a prioritized PDU, e.g., a “De-prioritized PDU” or a PDU which does not apply the prioritization discussed in this disclosure. The first bit may have a bit value of “1” which indicates that the PDU is a prioritized PDU. At least two second bits (e.g., Bit 1 and Bit 2) of the priority indicator may be set to indicate a sequence of prioritized PDUs comprising a current prioritized PDU (i.e., the PDU including this priority indicator). A receiving device (such as receiving PDCP entity) can determine whether a packet is prioritized or not just by examining the Bit 0.

[0087]

[0078] In an embodiment, a priority indicator may be used to indicate the following six types of PDUs according to configurations shown in FIG. 2B.

[0088] 1) Not Used (0,0,0): Indicates that the prioritization is not used for the current PDU (i.e. PDU including the priority indicator), in which case the receiving PDCP entity shall start the t-reordering timer for any missing PDCP PDU.

[0089] 2) De-prioritized (0,0,1): Indicates that the current PDCP PDU is considered as deprioritized PDU, but the receiving PDCP entity shall consider any missing of such PDCP PDU is allowed to be skipped and such PDCP PDU would be treated as if the PDCP PDU has been successfully received.

[0090] 3) Prioritized beginning (1,0,0): Indicates that the current PDCP PDU is considered as prioritized PDU, and marks a beginning of a sequence of prioritized PDUs. A receiving PDCP entity shall start a PDCP re-ordering timer for any missing PDCP PDU sequence starting from this PDCP PDU.

[0091] 4) Prioritized mid (1,0,1): Indicates that the current PDCP PDU is considered as prioritized PDU, and is part of the ongoing sequence for prioritized PDUs. Any missing of a PDCP PDU marked as prioritized mid shall trigger a PDCP re-ordering timer at the receiving PDCP entity. Such PDCP PDUs shall always be preceded by “Prioritized beginning” and followed by “Prioritized end”.

[0092] 5) Prioritized end (1,1,0): Indicates that the current PDCP PDU is considered as prioritized PDU, and marks an end of a sequence of prioritized PDUs.

[0093] 6) Prioritized single (1,1,1): Indicates that the current PDCP PDU is considered as prioritized PDU, and this sequence of prioritized PDUs contains only this single packet.

[0079] The given bit values are examples only and a reverse assignment of the bit values or entirely different bit values, especially in the case of multiple bits, may also be possible and depend on the specific implementation, as one of ordinary skill will understand.

[0094]

[0080] In the embodiments shown in FIG. 2A and 2B, the priority indicator is a single indication which has the form of a bit field comprising a plurality of bits. In this case, the plurality of bits comprises at least one first bit indicating whether the current PDCP PDU is a prioritized PDU or not, and at least two second bits indicating a sequence of prioritized PDUs if the current PDCP PDU is a prioritized PDU. In some other embodiments, the priority indicator may comprise a first indication indicating whether the current PDCP PDU is a prioritized PDU or not, and in case that the current PDCP PDU is a prioritized PDU, the priority indicator may further comprise a second indication indicating a sequence of prioritized PDUs comprising the current PDU.

[0095]

[0081] A PDCP entity at a receiving end may handle PDCP re-ordering timer for a missing of one or more consecutive PDCP PDUs according to types of received PDCP PDUs before and / or after the missed PDUs in PDCP SN sequence.

[0096]

[0082] In some embodiments, the receiving PDCP entity may determine that a reordering timer would not be started for a missing of one or more consecutive PDCP PDUs, under one of the following conditions:

[0097] • The missing PDU is a single PDU which is ordered between two PDUs which are “De-prioritized” PDUs according to PDCP SN;

[0098] • The missing PDU(s) is / are ordered after a “Prioritized end” PDU and before a “Prioritized single” PDU according to PDCP SN;

[0099] • The missing PDU(s) is / are ordered after a “Prioritized end” PDU and before a “Prioritized beginning” PDU according to PDCP SN;

[0100] • The missing PDU(s) is / are ordered after a “Prioritized single” PDU and before a “Prioritized beginning” PDU according to PDCP SN;

[0101] • The missing PDU(s) is / are ordered between two “Prioritized single” PDUs according to PDCP SN;

[0102] The missing PDU(s) is / are ordered after a “De-prioritized” PDU and before a “Prioritized single” PDU; • The missing PDU(s) is / are ordered after a “De-prioritized” PDU and before a “Prioritized beginning” PDU according to PDCP SN; or

[0103] • The missing PDU(s) is / are ordered after a “Prioritized end” PDU and before a “Deprioritized” PDU according to PDCP SN.

[0104]

[0083] Under any one of the above conditions, the receiving PDCP entity may start a reordering timer in alternative embodiments. In those alternative embodiment, under any one of the above conditions, the receiving PDCP entity may further determine whether or not to discard the missing PDU and avoid starting are-ordering timer, depending on delay tolerance (e.g., of associated application). For example, if a delay to be caused by reordering for the missing PDU is not acceptable, it may be determined to discard the missing PDU and avoid starting a re-ordering timer. Otherwise, if a delay to be caused by re-ordering for the missing PDU is acceptable, it may be determined to wait for receiving the missing PDU with starting a re-ordering timer.

[0105]

[0084] In an example, in case that a PDCP PDU which is marked as “Prioritized single” (which is typically a PDU with a PDCP SN between PDCP SNs of two “De-prioritized” PDUs) is not received at a receiving PDCP entity, the receiving PDCP entity would not know whether the missing PDU is a Prioritized PDU or not. In such cases, the receiving PDCP entity would not start a re-ordering timer according to an embodiment of the present disclosure. In an alternative embodiment, the receiving PDCP entity may start a re-ordering timer in this case. In another alternative embodiment, in this case, the receiving PDCP entity may determine whether or not to discard the missing PDU and avoid starting a re-ordering timer, depending on delay tolerance (e.g., of associated application). For example, if a delay to be caused by re-ordering for the missing PDU is not acceptable, it may be determined to discard the missing PDU and avoid starting a reordering timer. Otherwise, if a delay to be caused by re-ordering for the missing PDU is acceptable, it may be determined to wait for receiving the missing PDU with starting a re-ordering timer.

[0106]

[0085] In another example, in case that all PDCP PDUs are missing between a “Prioritized end” PDU (preceding the missing PDUs) and a “Prioritized single” PDU (following the missing PDUs), or between a “Prioritized end” PDU (preceding the missing PDUs) and a “Prioritized beginning” (preceding the missing PDUs), the receiving PDCP entity does not have exact knowledge about all of the priorities of the missing PDCP PDU(s). In such cases, the receiving PDCP entity would not start a re-ordering timer according to embodiments of the present disclosure. In an alternative embodiment, the receiving PDCP entity may start a re-ordering timer in this case. In another alternative embodiment, in this case, the receiving PDCP entity may determine whether or not to discard the missing PDU and avoid starting a re-ordering timer, depending on delay tolerance (e.g., of associated application). For example, if a delay to be caused by reordering for the missing PDU is not acceptable, it may be determined to discard the missing PDU and avoid starting a re-ordering timer. Otherwise, if a delay to be caused by re-ordering for the missing PDU is acceptable, it may be determined to wait for receiving the missing PDU with starting a re-ordering timer.

[0107]

[0086] In some embodiments, the receiving PDCP entity may determine that a reordering timer would be started for a missing of one or more consecutive PDCP PDUs, under one of the following conditions:

[0108] • If the missing PDCP PDU(s) is / are ordered before a “Prioritized mid” PDU or a “Prioritized end” PDU according to PDCP SN.

[0109] • If the missing PDCP PDU SN(s) is / are ordered before a “Prioritized single” PDU or a “Prioritized beginning” PDU according to PDCP SN, in case that the receiving PDCP entity also does not receive a “Prioritized end” PDU preceding the missing PDCP PDU SN(s).

[0110]

[0087] FIGs. 3A-3E and 4A-4E illustrate some exemplary procedures of data transfer according to an embodiment of the present disclosure.

[0111] Example 1 shown in FIG. 3 A:

[0112]

[0088] A transmitting device (e.g., gNB for downlink data transfer) has transmitted a sequence of PDCP PDUs with PDCP SNs 1-7. PDUs with SNs 5 and 6 have been deleted or de-prioritized at the receiving device, for example due to a delay for these PDUs or lower priority traffic associated with these PDUs. In this scenario, “Priority indicator” of each PDU may be set as below for this sequence of PDCP PDUs:

[0113] • PDU with SN 1 is marked as “Prioritized beginning”,

[0114] • PDUs with SNs 2 and 3 are marked as “Prioritized mid”,

[0115] • PDU with SN 4 is marked as “Prioritized end”,

[0116] PDUs with SNs 5 and 6 are marked “De-prioritized”,

[0117] PDU with SN 7 is marked as “Prioritized single”.

[0089] A receiving device (e.g., UE for downlink data transfer) received PDCP PDUs with SNs 1-4 and then received PDCP PDU with SN 7. When PDCP PDU with SN 7 is received, the receiving device may find that PDCP PDUs with SNs 5 and 6 are missing. Since the “Prioritized end” PDU is received at the receiving device with PDCP SN 4, and then PDCP PDU with SN 7 is received with a priority indicator indicating “Prioritized single”, the receiving device may determine that the missing PDCP PDUs with SNs 5 and 6 can be considered as de-prioritized PDUs, and can be skipped. As such, it can be determined that a PDCP re-ordering timer shall not be started due to a missing of PDCP PDUs with SNs 5 and 6.

[0118] Example 2 shown in FIG. 3B:

[0119]

[0090] A transmitting device (e.g., gNB for downlink data transfer) has transmitted a sequence of PDCP PDUs with PDCP SNs 1-8. PDUs with SNs 5 and 6 have been deleted or de-prioritized at the transmitting device. In this scenario, “Priority indicator” of each PDU may be set as below for this sequence of PDCP PDUs:

[0120] • PDU with SN 1 is marked as “Prioritized beginning”,

[0121] • PDUs with SNs 2 and 3 are marked as “Prioritized mid”,

[0122] • PDU with SN 4 is marked as “Prioritized end”,

[0123] • PDUs with SNs 5 and 6 are marked “De-prioritized”,

[0124] • PDU with SN 7 is marked as “Prioritized beginning”,

[0125] • PDU with SN 8 is marked as “Prioritized end”

[0126]

[0091] A receiving device (e.g., UE for downlink data transfer) received PDCP PDUs with SNs 1-4 and then received PDCP PDUs with SNs 7 and 8. When PDCP PDU with SN 7 is received, the receiving device may find that PDCP PDUs with SNs 5 and 6 are missing. Since the “Prioritized end” PDU is received at the receiving device with PDCP SN 4, and then PDCP PDU with SN 7 is received with a priority indicator indicating “Prioritized beginning”, the receiving device may determine that the missing PDCP PDUs with SNs 5 and 6 can be considered as de-prioritized PDUs, and can be skipped. As such, it can be determined that a PDCP re-ordering timer shall not be started due to a missing of PDCP PDUs with SNs 5 and 6.

[0127] Example 3 shown in FIG. 3C:

[0092] A transmitting device (e.g., gNB for downlink data transfer) has transmitted a sequence of PDCP PDUs with PDCP SNs 1-7. PDUs with SNs 5 and 7 have been deprioritized at the transmitting device. In this scenario, “Priority indicator” of each PDU may be set as below for this sequence of PDCP PDUs:

[0128] • PDU with SN 1 is marked as “Prioritized beginning”,

[0129] • PDUs with SNs 2 and 3 are marked as “Prioritized mid”,

[0130] • PDU with SN 4 is marked as “Prioritized end”,

[0131] • PDU with SN 5 is marked “De-prioritized”,

[0132] • PDU with SN 6 is marked as “Prioritized single”,

[0133] • PDU with SN 7 is marked as “De-prioritized”

[0134]

[0093] A receiving device (e.g., UE for downlink data transfer) received PDCP PDUs with SNs 1-5 and then received PDCP PDUs with SN 7. When PDCP PDU with SN 7 is received, the receiving device may find that PDCP PDU with SN 6 is missing. Since the “De-prioritized” PDU is received at the receiving device with PDCP SN 5, and then PDCP PDU with SN 7 is received with a priority indicator indicating “De-prioritized”, the receiving device may determine that the missing PDCP PDU with 6 can be skipped. As such, it can be determined that a PDCP re-ordering timer shall not be started due to a missing of PDCP PDU with SN 6.

[0135] Example 4 shown in FIG. 3D:

[0136]

[0094] A transmitting device (e.g., gNB for downlink data transfer) has transmitted a sequence of PDCP PDUs with PDCP SNs 1-8. PDUs with SNs 4 and 6 have been deprioritized at the transmitting device. In this scenario, “Priority indicator” of each PDU may be set as below for this sequence of PDCP PDUs:

[0137] • PDU with SN 1 is marked as “Prioritized beginning”,

[0138] • PDU with SN 2 is marked as “Prioritized mid”,

[0139] • PDU with SN 3 is marked as “Prioritized end”,

[0140] • PDU with SN 4 is marked as “De-prioritized ”,

[0141] PDU with SN 5 is marked “Prioritized single”,

[0142] PDU with SN 6 is marked as “De-prioritized”, • PDU with SN 7 is marked as “Prioritized beginning”,

[0143] • PDU with SN 8 is marked as “Prioritized end”.

[0144]

[0095] A receiving device (e.g., UE for downlink data transfer) received PDCP PDUs with SNs 1-5 and then received PDCP PDUs with SNs 7 and 8. When PDCP PDU with SN 7 is received, the receiving device may find that PDCP PDU with SN 6 is missing. Since the “Prioritized single” PDU is received at the receiving device with PDCP SN 5, and then PDCP PDU with SN 7 is received with a priority indicator indicating “Prioritized beginning”, the receiving device may determine that the missing PDCP PDU with 6 can be considered as de-prioritized PDUs, and can be skipped. As such, it can be determined that a PDCP re-ordering timer shall not be started due to a missing of PDCP PDU with SN 6.

[0145] Example 5 shown in FIG. 3E:

[0146]

[0096] A transmitting device (e.g., gNB for downlink data transfer) has transmitted a sequence of PDCP PDUs with PDCP SNs 1-8. PDUs with SNs 4, 6 and 8 have been deleted or de-prioritized at the transmitting device. In this scenario, “Priority indicator” of each PDU may be set as below for this sequence of PDCP PDUs:

[0147] • PDU with SN 1 is marked as “Prioritized beginning”,

[0148] • PDU with SN 2 is marked as “Prioritized mid”,

[0149] • PDU with SN 3 is marked as “Prioritized end”,

[0150] • PDU with SN 4 is marked as “De-prioritized ”,

[0151] • PDU with SN 5 is marked “Prioritized single”,

[0152] • PDU with SN 6 is marked as “De-prioritized”,

[0153] • PDU with SN 7 is marked as “Prioritized single”,

[0154] • PDU with SN 8 is marked as “De-prioritized”.

[0155]

[0097] A receiving device (e.g., UE for downlink data transfer) received PDCP PDUs with SNs 1-5 and then received PDCP PDUs with SNs 7 and 8. When PDCP PDU with SN 7 is received, the receiving device may find that PDCP PDU with SN 6 is missing. Since the “Prioritized single” PDU is received at the receiving device with PDCP SN 5, and then PDCP PDU with SN 7 is received with a priority indicator indicating “Prioritized single”, the receiving device may determine that the missing PDCP PDU with 6 can be considered as de-prioritized PDUs, and can be skipped. As such, it can be determined that a PDCP re-ordering timer shall not be started due to a missing of PDCP PDU with SN 6.

[0156] Example 6 shown in FIG. 4A:

[0157]

[0098] A transmitting device (e.g., gNB for downlink data transfer) has transmitted a sequence of PDCP PDUs with PDCP SNs 1-9. PDUs with SNs 5 and 6 have been deleted or de-prioritized at the transmitting device. In this scenario, “Priority indicator” of each PDU may be set as below for this sequence of PDCP PDUs:

[0158] • PDU with SN 1 is marked as “Prioritized beginning”,

[0159] • PDUs with SNs 2 and 3 are marked as “Prioritized mid”,

[0160] • PDU with SN 4 is marked as “Prioritized end”,

[0161] • PDUs with SNs 5 and 6 are marked “De-prioritized”,

[0162] • PDU with SN 7 is marked as “Prioritized beginning”,

[0163] • PDU with SN 8 is marked as “Prioritized mid”,

[0164] • PDU with SN 9 is marked as “Prioritized end”.

[0165]

[0099] A receiving device (e.g., UE for downlink data transfer) received PDCP PDUs with SNs 1-4 and then received PDCP PDU with SN 7. At this point, the receiving device may find that PDCP PDUs with SNs 5 and 6 is missing. Since the missing PDCP PDUs (with SNs 5 and 6) are in between a “Prioritized end” PDU (with PDCP SN 4) and a “Prioritized beginning” PDU (with PDCP SN 7). So, these PDCP SNs 5 and 6 are skipped, and PDCP re-ordering timer shall not be started due to missing PDCP SN 5 and 6.

[0166]

[0100] Then, the receiving device receives PDCP PDU with SN 9 which includes a priority indicator of “Prioritized end”. At this point, the receiving device may find that PDCP PDU with SN 8 is missing. Since there is a missing PDU between a “Prioritized beginning” PDU (with PDCP SN 7) and a “Prioritized end” PDU (with PDCP SN 9), the receiving device may determine that the missing PDU can be considered as Prioritized PDU, and is not allowed to be skipped. Then, a re-ordering timer is started at the receiving device.

[0167] Example 7 shown in FIG. 4B:

[0101] A transmitting device (e.g., gNB for downlink data transfer) has transmitted a sequence of PDCP PDUs with PDCP SNs 1-9. PDUs with SNs 5 and 6 have been deleted or de-prioritized at the transmitting device. In this scenario, “Priority indicator” of each PDU may be set as below for this sequence of PDCP PDUs:

[0168] • PDU with SN 1 is marked as “Prioritized beginning”,

[0169] • PDUs with SNs 2 and 3 are marked as “Prioritized mid”,

[0170] • PDU with SN 4 is marked as “Prioritized end”,

[0171] • PDUs with SNs 5 and 6 are marked “De-prioritized”,

[0172] • PDU with SN 7 is marked as “Prioritized beginning”,

[0173] • PDU with SN 8 is marked as “Prioritized mid”,

[0174] • PDU with SN 9 is marked as “Prioritized end”.

[0175]

[0102] A receiving device (e.g., UE for downlink data transfer) received PDCP PDUs with SNs 1-3 and then received PDCP PDU with SN 7. At this point, the receiving device may find that PDCP PDUs with SNs 4, 5 and 6 is missing. Since the “Prioritized end” PDU (with PDCP SN 4) is missing while there is a “Prioritized beginning” PDU (with PDCP SN 7) received, the re-ordering timer would be started at the receiving device.

[0176]

[0103] Upon a reception of the PDCP PDU with SN 4, the PDCP re-ordering timer would be stopped because the “Prioritized end” PDU has been received and now the missing PDCP SN 5 and 6 are in between “Prioritized end” PDU (with PDCP SN 4) and a “Prioritized beginning” PDU (with PDCP SN 7). These PDUs with PDCP SNs 5 and 6 can be skipped as they are considered as deprioritized.

[0177]

[0104] When the receiving device receives PDCP PDU with SN 9 which includes a priority indicator of “Prioritized end”, the receiving device may find that PDCP PDU with SN 8 is missing. Since there is a missing PDCP PDU before a “Prioritized end” PDU, the re-ordering timer would be started for the missing PDCP PDU of SN 8. In this case, the PDCP re-ordering timer would be stopped only upon a reception of PDCP PDU of SN 8.

[0178] Example 8 shown in FIG. 4C:

[0179]

[0105] A transmitting device (e.g., gNB for downlink data transfer) has transmitted a sequence of PDCP PDUs with PDCP SNs 1-8. PDUs with SNs 5 and 6 have been deleted or de-prioritized at the transmitting device. In this scenario, “Priority indicator” of each PDU may be set as below for this sequence of PDCP PDUs: PDU with SN 1 is marked as “Prioritized beginning”,

[0180] PDUs with SNs 2 and 3 are marked as “Prioritized mid”,

[0181] • PDU with SN 4 is marked as “Prioritized end”,

[0182] • PDUs with SNs 5 and 6 are marked “De-prioritized”,

[0183] • PDU with SN 7 is marked as “Prioritized single”,

[0184] • PDU with SN 8 is marked as “Not Used”.

[0185]

[0106] A receiving device (e.g., UE for downlink data transfer) received PDCP PDUs with SNs 1-3 and then received PDCP PDU with SN 7. At this point, the receiving device may find that PDCP PDUs with SNs 4, 5 and 6 are missing. Since the “Prioritized end” PDU (with PDCP SN 4) is missing while there is a “Prioritized single” PDU (with PDCP SN 7) received, the re-ordering timer is started at the receiving device.

[0186]

[0107] Upon a reception of the PDCP PDU with SN 4, the PDCP re-ordering timer would be stopped because the “Prioritized end” PDU has been received and now the missing PDCP SN 5 and 6 are in between “Prioritized end” PDU (with PDCP SN 4) and a “Prioritized single” PDU (with PDCP SN 7). These PDUs with PDCP SNs 5 and 6 can be skipped as they are considered as deprioritized.

[0187] Example 9 shown in FIG. 4D:

[0188]

[0108] A transmitting device (e.g., gNB for downlink data transfer) has transmitted a sequence of PDCP PDUs with PDCP SNs 1-10. PDUs with SNs 5 and 6 have been deprioritized at the transmitting device. In this scenario, “Priority indicator” of each PDU may be set as below for this sequence of PDCP PDUs:

[0189] • PDU with SN 1 is marked as “Prioritized beginning”,

[0190] • PDUs with SNs 2 and 3 are marked as “Prioritized mid”,

[0191] • PDU with SN 4 is marked as “Prioritized end”,

[0192] • PDUs with SNs 5 and 6 are marked “De-prioritized”,

[0193] • PDU with SN 7 is marked as “Prioritized beginning”,

[0194] • PDUs with SNs 8 and 9 are marked as “Prioritized mid”,

[0195] PDU with SN 10 is marked as “Prioritized end”.

[0109] A receiving device (e.g., UE for downlink data transfer) received PDCP PDUs with SNs 1-7 and then received PDCP PDU with SN 10. At this point, the receiving device may find that PDCP PDUs with SNs 8 and 9 are missing. Since the missing PDCP PDU is between a “Prioritized beginning” PDU (with PDCP SN 7) and a “Prioritized end” PDU (with PDCP SN 10), the PDCP re-ordering timer would be started at the receiving device. In this case the PDCP re-ordering timer would be stopped only upon a reception of PDCP PDUs with SNs 8 and 9.

[0196] Example 10 shown in FIG. 4E:

[0197]

[0110] A transmitting device (e.g., gNB for downlink data transfer) has transmitted a sequence of PDCP PDUs with PDCP SNs 1-810. PDUs with SNs 5 and 6 have been deprioritized at the transmitting device. In this scenario, “Priority indicator” of each PDU may be set as below for this sequence of PDCP PDUs:

[0198] • PDU with SN 1 is marked as “Prioritized beginning”,

[0199] • PDUs with SNs 2 and 3 are marked as “Prioritized mid”,

[0200] • PDU with SN 4 is marked as “Prioritized end”,

[0201] • PDUs with SNs 5 and 6 are marked “De-prioritized”,

[0202] • PDU with SN 7 is marked as “Prioritized beginning”,

[0203] • PDU with SN 8 is marked as “Prioritized mid”.

[0204]

[0111] A receiving device (e.g., UE for downlink data transfer) received PDCP PDUs with SNs 1-6 and then received PDCP PDU with SN 8. At this point, the receiving device may find that PDCP PDU with SN 7 is missing. Since the missing PDCP PDU is before a “Prioritized mid” PDU (with PDCP SN 8), the PDCP re-ordering timer would be started at the receiving device. In this case the PDCP re-ordering timer would be stopped only upon a reception of PDCP PDU with SN 7.

[0205]

[0112] FIG. 5 is a flow chart depicting a method 500 performed at a transmitting device (e.g., at a transmitting PDCP entity) according to embodiments of the present disclosure. In an example, the method may be performed by a terminal device (e.g., UE), or an apparatus for use in a terminal device, for uplink transmission. In another example, the method may be performed by a network node (e.g., gNB), or an apparatus for use in a network node, for downlink transmission.

[0113] At block 510, the transmitting device (e.g., a network node for downlink transmission or a terminal device for uplink transmission) may include into each packet of a sequence of packets, a priority indicator indicating whether respective packets are prioritized packets a missing of which in the in-order delivery is not allowed to be skipped. In case that a packet is a prioritized packet, a priority indicator included in the prioritized packet further indicates a sequence of prioritized packets comprising the prioritized packet.

[0206]

[0114] The sequence of packets is comprised of one or more packets assigned consecutive sequence numbers. In an embodiment, the sequence of packets may be a sequence of PDCP PDUs.

[0207]

[0115] The sequence of prioritized packets is comprised of one or more prioritized packets assigned consecutive sequence numbers.

[0208]

[0116] A priority indicator of a prioritized packet may indicate its position in a sequence of prioritized packet. In an example, a priority indicator included in a packet may indicate that the packet is of one of the following types: a beginning prioritized packet, ordered at a beginning of a sequence of prioritized packets, a middle prioritized packet, ordered in the middle of a sequence of prioritized packets, or an end prioritized packet, ordered at an end of a sequence of prioritized packets. In an example, a priority indicator included in a packet may indicate whether the packet is a single prioritized packet in a sequence of prioritized packets comprising only one prioritized packet.

[0209]

[0117] In an example, a priority indicator included in a packet may indicate that the packet is a de-prioritized packet, a missing of which in the in-order delivery is allowed to be skipped.

[0210]

[0118] The priority indicator may be comprised of at least 3 bits, for example configured as depicted in FIG. 2B.

[0211]

[0119] In an example, the priority indicator may be comprised in a header of a packet, e.g., utilizing reserved bits of the header.

[0212]

[0120] At block 520, the transmitting device transmits the sequence of packets to a receiving device (e.g., a terminal device for downlink transmission or a network node for uplink transmission).

[0213]

[0121] FIG. 6 is a flow chart depicting a method 600 performed at a receiving device (e.g., at a receiving PDCP entity) according to embodiments of the present disclosure. In an example, the method may be performed by a terminal device (e.g., UE), or an apparatus for use in a terminal device, for downlink transmission. In another example, the method may be performed by a network node (e.g., gNB), or an apparatus for use in a network node, for uplink transmission.

[0214]

[0122] At block 610, areceiving device (e.g., aterminal device for downlink transmission or a network node for uplink transmission) try to receive a sequence of packets from a transmitting device (e.g., a network node for downlink transmission or a terminal device for uplink transmission). Each packet of the sequence of packets includes a priority indicator indicating whether respective packets are prioritized packets, a missing of which in the in-order delivery is not allowed to be skipped. In case that a packet is a prioritized packet, a priority indicator included in the prioritized packet further indicates a sequence of prioritized packets comprising the prioritized packet.

[0215]

[0123] The sequence of packets may correspond to that transmitted at block 520. Details regarding the sequence of packets and priority indicator have already been described above in connection with the description of FIG. 5. Repetition is omitted here for reasons of clarity and ease of understanding. Instead, reference is made to the above explanations.

[0216]

[0124] At block 620, the receiving device determines whether a missing of one or more consecutive packets of the sequence of packets is to be skipped, based on respective priority indicators of received packets before and / or after the one or more consecutive packets in the sequence of packets. In this regard, upon the receiving device receives a packet while one or more consecutive packets preceding the received packet according to sequence numbers have not been received, the receiving device may determine that the one or more consecutive packets are missing. Then, the receiving device may determine whether the missing packets can be discarded, based on respective priority indicators of received packets in the sequence of packets.

[0217]

[0125] FIG. 7 is a flow chart depicting a method 700 performed at a receiving device according to another embodiment of the present disclosure. Block 710 may be implemented as or comprised in block 620 of FIG. 6. For some parts which have been described in the above embodiments, the description thereof is omitted here for brevity.

[0218]

[0126] At block 710, the receiving device may check priority indicators of received packets before and / or after the one or more missing packets to determine whether any one of a first group of conditions, which comprises at least one of following conditions #1 to #7, is met or not: • Condition #1 : the one or more missing packets is one packet between two received packets which include priority indicators (such as, indicator “Deprioritized” shown in FIG. 2B) indicating that the two packets are not prioritized packets,

[0219] • Condition #2: the one or more missing packets are after a received packet which includes a priority indicator (such as, indicator “Prioritized end” shown in FIG. 2B) indicating that the received packet is an end of a sequence of prioritized packets, and before another received packet which includes a priority indicator (such as, indicator “Prioritized single” shown in FIG. 2B) indicating that the another received packet is in a sequence of prioritized packets comprising only one prioritized packet or is a beginning of a sequence of prioritized packets,

[0220] • Condition #3 : the one or more missing packets are after a received packet which includes a priority indicator (such as, indicator “Prioritized single” shown in FIG. 2B) indicating that the received packet is in a sequence of prioritized packets comprising only one prioritized packet, and before another received packet which includes a priority indicator (such as, indicator “Prioritized beginning” shown in FIG. 2B) indicating that the another received packet is a beginning of a sequence of prioritized,

[0221] • Condition #4: the one or more missing packets are between two received packets which include priority indicators (such as, indicator “Prioritized single” shown in FIG. 2B) indicating that each of the two packets is in a sequence of prioritized packets comprising only one prioritized packet;

[0222] • Condition #5: the one or more missing packets are after a received packet which includes a priority indicator (such as, indicator “De-prioritized” shown in FIG. 2B) indicating that the packet is not a prioritized packet, and before another received packet which includes a priority indicator (such as, indicator “Prioritized single” shown in FIG. 2B) indicating that the another received packet is in a sequence of prioritized packets comprising only one prioritized packet;

[0223] • Condition #6: the one or more missing packets are after a received packet which includes a priority indicator (such as, indicator “De-prioritized” shown in FIG. 2B) indicating that the packet is not a prioritized packet, and before another received packet which includes a priority indicator (such as, indicator “Prioritized beginning” shown in FIG. 2B) indicating that the another received packet is a beginning of a sequence of prioritized; or

[0224] • Condition #7: the one or more missing packets are after a received packet which includes a priority indicator (such as, indicator “Prioritized end” shown in FIG. 2B) indicating that the received packet is an end of a sequence of prioritized packets, and before another received packet which includes a priority indicator (such as, indicator “De-prioritized” shown in FIG. 2B) indicating that the another packet is not a prioritized packet.

[0225]

[0127] At block 720, the receiving device may discard the one or more missing packets without starting a re-ordering timer, if any one of conditions #1 to #7 is met. In this regard, the receiving device determines that a missing of the one or more missing packets can be skipped. Thus, no re-ordering timer would be started due to the missing of the one or more missing packets.

[0226]

[0128] In some embodiments, when the one or more missing packets is received later, they may be delivered to an upper layer in an out-of-order delivery, e.g., from a PDCP layer to SDAP / RLC layer.

[0227]

[0129] In an alternative embodiment, the receiving device may further determine if a delay to be caused by a re-ordering for the one or more missing packets is acceptable. If it is determined that the delay is acceptable, the receiving device may wait for a receipt of the one or more missing packets with starting a re-ordering timer. If it is determined that the delay is not acceptable, the receiving device may discard the one or more consecutive packets without starting a re-ordering timer.

[0228]

[0130] FIG. 8 is a flow chart depicting a method 800 performed at a receiving device according to yet another embodiment of the present disclosure. Block 810 may be implemented as or comprised in block 620 of FIG. 6. For some parts which have been described in the above embodiments, the description thereof is omitted here for brevity.

[0229]

[0131] At block 810, the receiving device may check priority indicators of received packets before and / or after the one or more missing packets to determine whether any one of a second group of conditions, which comprises at least one of the following conditions #8 and #9, is met or not:

[0230] • Condition #8: the one or more consecutive packets are before a received packet which includes a priority indicator (such as, indicator “Prioritized mid” shown in FIG. 2B) indicating that the received packet is in the middle, or a priority indicator (such as, indicator “Prioritized end” shown in FIG. 2B) indicating that the received packet is an end of a sequence of prioritized packets, or

[0231] • Condition #9: the one or more missing packets are before a received packet which includes a priority indicator (such as, indicator “Prioritized single” shown in FIG. 2B) indicating that the received packet is in a sequence of prioritized packets comprising only one prioritized packet or a priority indicator (such as, indicator “Prioritized beginning” shown in FIG. 2B) indicating that the received packet is a beginning of a sequence of prioritized packets, in case that a prioritized packet of an end of a sequence of prioritized packets before the one or more consecutive packets has not been received at the receiving device.

[0232]

[0132] At block 820, the receiving device may wait for a receipt of the one or more missing packets with starting a re-ordering timer, if any one of conditions #8 and #9 is met.

[0233]

[0133] Embodiments herein may enable on demand discarding of packets (such as PDCP PDUs) with the support for in-order delivery, e.g., at PDCP layer. The embodiments herein are not limited to the features and advantages mentioned above. A person skilled in the art will recognize additional features and advantages upon reading the following detailed description.

[0234]

[0134] FIG. 9 shows, by way of example, a block diagram of an apparatus 10, that may be embodied in / as the terminal device, or the network node. The apparatus 10 comprises, for example, at least one processor 12 and at least one memory 14 storing instructions 15 that, when executed by the at least one processor, cause the apparatus 10 at least to perform the method or methods as disclosed herein, and any of the embodiments thereof. In an example, the at least one memory and the instructions (e.g. a computer program code, software), are configured, with the at least one processor, to cause the apparatus 10 to perform the method or methods as disclosed herein, and any of the embodiments thereof.

[0235]

[0135] A processor 12 may comprise circuitry, or be constituted as circuitry or circuitries, the circuitry or circuitries being configured to perform phases of methods in accordance with example embodiments described herein. As used in this application, the term

[0236] “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations, such as implementations in only analog and / or digital circuitry, and (b) combinations of hardware circuits and software, such as, as applicable: (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a user equipment, to perform various functions) and (c) hardware circuit(s) and or processor(s), such as a microprocessor s) or a portion of a microprocessor s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation. This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

[0237]

[0136] The memory 14 may be implemented using any suitable data storage technology. The memory may comprise a database for storing data. The memory 14 may be at least in part external to apparatus 10 but accessible to apparatus 10.

[0238]

[0137] The instructions 15 may be comprised in a computer readable medium or a non- transitory computer readable medium. A term non-transitory, as used herein, is a limitation of the medium itself (i.e. tangible, not a signal) as opposed to a limitation on data storage persistency (e.g. random access memory, RAM, vs. read only memory, ROM).

[0239]

[0138] For example, the apparatus 10 is a transmitting device, e.g., a base station or a terminal device. As another example, the apparatus is comprised in such a transmitting device, e.g. as a chipset configured to control the transmitting device. The apparatus 10 may be caused or configured to perform at least the method of FIG. 5 and / or any one or more of the embodiments described.

[0240]

[0139] As another example, the apparatus 10 is a receiving device, e.g. a base station or a terminal device. In another embodiment, the apparatus is comprised in such a receiving device, e.g. as a chipset configured to control the receiving device. The apparatus 10 may be caused or configured to perform at least the method of FIGs. 6-8 and / or any one or more of the embodiments described.

[0140] The apparatus may comprise one or more entities of any of protocol layers, such as a MAC entity, an RRC entity, an RLC entity, a PDCP entity or a PHY entity. In some embodiments, the entity is configured to perform at least the method of FIGs. 5-8, and / or any one or more of the embodiments described.

[0241]

[0141] The apparatus 10 comprises a radio interface 16. The radio interface 16 may provide the apparatus 10 with communication capabilities. The radio interface 16 may comprise a receiver configured to receive information in accordance with at least one cellular or non-cellular standard. The radio interface 16 may comprise a transmitter configured to transmit information in accordance with at least one cellular or non-cellular standard. The receiver may comprise more than one receiver. The transmitter may comprise more than one transmitter. The radio interface 16 may comprise a transceiver configured to receive and transmit information in accordance with at least one cellular or non-cellular standard. The transceiver may comprise more than one transceiver.

[0242]

[0142] The apparatus 10 may comprise a user interface 18 comprising, for example, at least one of a keypad, a microphone, a touch display, a display, a speaker, etc. The user interface 18 may be used to control the apparatus by the user. The user interface 18 may be external to the apparatus 10. For example, the apparatus 10 may be connected to another device, such as a computer, either via wireless or wired connection, and the apparatus 10 is controlled by the user via the computer.

[0243]

[0143] In an embodiment, at least some of the processes described herein may be carried out by an apparatus comprising means for carrying out at least some of the described processes. Means for performing method steps as disclosed herein may include software and / or hardware components of the apparatus 10. For example, the at least one processor 12, the memory 14, and the computer program code form means for carrying out the method or methods as disclosed herein, and any of the embodiments thereof. As used herein the term “means” is to be construed in singular form, i.e. referring to a single element, or in plural form, i.e. referring to a combination of single elements. Therefore, terminology “means for [performing A, B, C]”, is to be interpreted to cover an apparatus in which there is only one means for performing A, B and C, or where there are separate means for performing A, B and C, or partially or fully overlapping means for performing A, B, C. Further, terminology “means for performing A, means for performing B, means for performing C” is to be interpreted to cover an apparatus in which there is only one means for performing A, B and C, or where there are separate means for performing A, B and C, or partially or fully overlapping means for performing A, B, C.

[0144] It should be appreciated that at least some aspects of the exemplary embodiments of the disclosures may be embodied in computer-executable instructions, such as in one or more program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types when executed by a processor in a computer or other device. The computer executable instructions may be stored on a computer readable medium, for example, non-transitory computer readable medium, such as a hard disk, optical disk, removable storage media, solid state memory, RAM, etc. As will be appreciated by one of skills in the art, the function of the program modules may be combined or distributed as desired in various embodiments. In addition, the function may be embodied in whole or in part in firmware or hardware equivalents such as integrated circuits, field programmable gate arrays (FPGA), and the like.

[0244]

[0145] Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

[0245]

[0146] Even though the invention has been described above with reference to an example according to the accompanying drawings, it is clear that the invention is not restricted thereto but may be modified in several ways within the scope of the appended claims. Therefore, all words and expressions should be interpreted broadly and they are intended to illustrate, not to restrict, the embodiment. It will be obvious to a person skilled in the art that, as technology advances, the inventive concept may be implemented in various ways. Further, it is clear to a person skilled in the art that the described embodiments may, but are not required to, be combined with other embodiments in various ways.

Claims

36CLAIMS1. An apparatus for in-order delivery in a transmitting device, the apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: include into each packet of a sequence of packets, a priority indicator indicating whether respective packets are prioritized packets a missing of which in the in-order delivery is not allowed to be skipped, and wherein in case that a packet is a prioritized packet, a priority indicator included in the prioritized packet further indicates a sequence of prioritized packets comprising the prioritized packet; and transmit the sequence of packets to a receiving device.

2. The apparatus according to claim 1, wherein in case that a packet is a prioritized packet, a priority indicator included in the packet further indicates that the packet is of one of the following types: a beginning prioritized packet, ordered at a beginning of a sequence of prioritized packets, a middle prioritized packet, ordered in the middle of a sequence of prioritized packets, or an end prioritized packet, ordered at an end of a sequence of prioritized packets.

3. The apparatus according to any of claims 1 to 2, wherein in case that a packet is a prioritized packet, a priority indicator included in the packet further indicates whether the packet is a single prioritized packet in a sequence of prioritized packets comprising only one prioritized packet.

4. The apparatus according to any of claims 1 to 3, wherein in case that a packet is not a prioritized packet, a priority indicator included in the packet further indicates that the packet is a de-prioritized packet, a missing of which in the in-order delivery is allowed to be skipped.

5. The apparatus according to any of claims 1 to 4, wherein a priority indicator included in a packet comprises at least one first bit indicating whether the packet is a prioritized packet or not, and37 wherein a priority indicator included in a prioritized packet further comprises at least two second bits indicating a sequence of prioritized packets comprising the prioritized packet.

6. The apparatus according to any of claims 1 to 5, wherein a priority indicator is comprised of at least 3 bits.

7. The apparatus according to any of claims 1 to 6, wherein a priority indicator is comprised in a header of a packet.

8. The apparatus according to any of claims 1 to 7, wherein the sequence of packets is a sequence of protocol data units, PDUs, of packet data convergence protocol, PDCP.

9. The apparatus according to any of claims 1 to 8, wherein the transmitting device is a base station or a user equipment.

10. An apparatus for in-order delivery in a receiving device, the apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: try to receive a sequence of packets from a transmitting device, wherein each packet includes a priority indicator indicating whether respective packets are prioritized packets a missing of which in the in-order delivery is not allowed to be skipped, and wherein in case that a packet is a prioritized packet, a priority indicator included in the prioritized packet further indicates a sequence of prioritized packets comprising the prioritized packet; and determine whether a missing of one or more consecutive packets of the sequence of packets is to be skipped based on respective priority indicators of received packets before and / or after the one or more consecutive packets in the sequence of packets.

11. The apparatus according to claim 10, wherein the apparatus is caused to determine whether the missing of the one or more packets is to be skipped by, determining that the missing of the one or more consecutive packets is to be skipped under any one of one or more conditions comprising at least one of following conditions, the one or more consecutive packets is one packet between two received packetswhich include priority indicators indicating that the two packets are not prioritized packets, the one or more consecutive packets are after a received packet which includes a priority indicator indicating that the received packet is an end of a sequence of prioritized packets, and before another received packet which includes a priority indicator indicating that the another received packet is in a sequence of prioritized packets comprising only one prioritized packet or is a beginning of a sequence of prioritized packets, the one or more consecutive packets are after a received packet which includes a priority indicator indicating that the received packet is in a sequence of prioritized packets comprising only one prioritized packet, and before another received packet which includes a priority indicator indicating that the another received packet is a beginning of a sequence of prioritized, the one or more consecutive packets are between two received packets which include priority indicators indicating that each of the two packets is in a sequence of prioritized packets comprising only one prioritized packet, the one or more missing packets are after a received packet which includes a priority indicator indicating that the packet is not a prioritized packet, and before another received packet which includes a priority indicator indicating that the another received packet is in a sequence of prioritized packets comprising only one prioritized packet, the one or more missing packets are after a received packet which includes a priority indicator indicating that the packet is not a prioritized packet, and before another received packet which includes a priority indicator indicating that the another received packet is a beginning of a sequence of prioritized, or the one or more missing packets are after a received packet which includes a priority indicator indicating that the received packet is an end of a sequence of prioritized packets, and before another received packet which includes a priority indicator indicating that the another packet is not a prioritized packet.

12. The apparatus according to claim 11, wherein when the instructions are executed by the at least one processor, the instructions further cause the apparatus at least to, discard the one or more consecutive packets without starting a re-ordering timer.

13. The apparatus according to claim 11, wherein when the instructions are executed by the at least one processor, the instructions further cause the apparatus at least to,determine if a delay to be caused by a re-ordering for the one or more consecutive packets is acceptable; and wait for a receipt of the one or more consecutive packets with starting a re-ordering timer if it is determined that the delay is acceptable, or discard the one or more consecutive packets without starting a re-ordering timer if it is determined that the delay is not acceptable.

14. The apparatus according to any of claims 10 to 13, wherein the apparatus is caused to determine whether the missing of the one or more consecutive packets is to be skipped by, determining that the missing of the one or more consecutive packets is not to be skipped under any one of one or more conditions comprising at least one of following conditions, the one or more consecutive packets are before a received packet which includes a priority indicator indicating that the received packet is in the middle or is an end of a sequence of prioritized packets, or the one or more consecutive packets are before a received packet which includes a priority indicator indicating that the received packet is in a sequence of prioritized packets comprising only one prioritized packet or is a beginning of a sequence of prioritized packets, in case that a prioritized packet of an end of a sequence of prioritized packets before the one or more consecutive packets has not been received at the receiving device.

15. The apparatus according to claim 14, wherein when the instructions are executed by the at least one processor, the instructions further cause the apparatus at least to, wait for a receipt of the one or more consecutive packets with starting a re-ordering timer.

16. The apparatus according to any of claims 10 to 15, wherein in case that a packet is a prioritized packet, a priority indicator included in the packet further indicates that the packet is of one of the following types: a beginning prioritized packet, ordered at a beginning of a sequence of prioritized packets, a middle prioritized packet, ordered in the middle of a sequence of prioritized packets, or an end prioritized packet, ordered at an end of a sequence of prioritized packets.

17. The apparatus according to claim 10 to 16, wherein in case that a packet is a prioritized packet, a priority indicator included in the packet further indicates whether the packet is a single prioritized packet in a sequence of prioritized packets comprising only one prioritized packet.

18. The apparatus according to any of claims 10 to 17, wherein in case that a packet is not a prioritized packet, a priority indicator included in the packet further indicates that the packet is a de-prioritized packet, a missing of which in the in-order delivery is allowed to be skipped.

19. The apparatus according to any of claims 10 to 18, wherein a priority indicator included in a packet comprises at least one first bit indicating whether the packet is a prioritized packet or not, and wherein a priority indicator included in a prioritized packet further comprises at least two second bits indicating a sequence of prioritized packets comprising the prioritized packet.

20. The apparatus according to any of claims 10 to 19, wherein a priority indicator is comprised of at least 3 bits.

21. The apparatus according to any of claims 10 to 20, wherein a priority indicator is comprised in a header of a packet.

22. The apparatus according to any of claims 10 to 21, wherein the sequence of packets is a sequence of packets protocol data units, PDUs, of packet data convergence protocol, PDCP.

23. The apparatus according to any of claims 10 to 22, wherein the receiving device is a base station or a user equipment.

24. A method for in-order delivery in a transmitting device, the method comprising: including into each packet of a sequence of packets, a priority indicator indicating whether respective packets are prioritized packets a missing of which in the in-order delivery is not allowed to be skipped, and wherein in case that a packet is a prioritized packet, a priority indicator included in the prioritized packet further indicates a sequence41 of prioritized packets comprising the prioritized packet; and transmitting the sequence of packets to a receiving device.

25. A method for in-order delivery in a receiving device, the method comprising: trying to receive a sequence of packets from a transmitting device, wherein each packet includes a priority indicator indicating whether respective packets are prioritized packets a missing of which in the in-order delivery is not allowed to be skipped, and wherein in case that a packet is a prioritized packet, a priority indicator included in the prioritized packet further indicates a sequence of prioritized packets comprising the prioritized packet; and determining whether a missing of one or more consecutive packets of the sequence of packets is to be skipped based on respective priority indicators of received packets before and / or after the one or more packets in the sequence of packets.

26. The method according to claim 25, wherein determining whether the missing of the one or more packets is to be skipped comprises, determining that the missing of the one or more consecutive packets is to be skipped under any one of one or more conditions comprising at least one of following conditions, the one or more consecutive packets is one packet between two received packets which include priority indicators indicating that the two packets are not prioritized packets, the one or more consecutive packets are after a received packet which includes a priority indicator indicating that the received packet is an end of a sequence of prioritized packets, and before another received packet which includes a priority indicator indicating that the another received packet is in a sequence of prioritized packets comprising only one prioritized packet or is a beginning of a sequence of prioritized packets, the one or more consecutive packets are after a received packet which includes a priority indicator indicating that the received packet is in a sequence of prioritized packets comprising only one prioritized packet, and before another received packet which includes a priority indicator indicating that the another received packet is a beginning of a sequence of prioritized, the one or more consecutive packets are between two received packets which include priority indicators indicating that each of the two packets is in a sequence of prioritized packets comprising only one prioritized packet, the one or more missing packets are after a received packet which includes a42 priority indicator indicating that the packet is not a prioritized packet, and before another received packet which includes a priority indicator indicating that the another received packet is in a sequence of prioritized packets comprising only one prioritized packet, the one or more missing packets are after a received packet which includes a priority indicator indicating that the packet is not a prioritized packet, and before another received packet which includes a priority indicator indicating that the another received packet is a beginning of a sequence of prioritized, or the one or more missing packets are after a received packet which includes a priority indicator indicating that the received packet is an end of a sequence of prioritized packets, and before another received packet which includes a priority indicator indicating that the another packet is not a prioritized packet.

27. The method according to claim 26, further comprising, discarding the one or more consecutive packets without starting a re-ordering timer.

28. The method according to claim 26, further comprising, determining if a delay to be caused by a re-ordering for the one or more consecutive packets is acceptable; and waiting for a receipt of the one or more consecutive packets with starting a reordering timer if it is determined that the delay is acceptable, or discarding the one or more consecutive packets without starting a re-ordering timer if it is determined that the delay is not acceptable.

29. The method according to claim 25, wherein determining whether the missing of the one or more packets is to be skipped comprises, determining that the missing of the one or more consecutive packets is not to be skipped under any one of one or more conditions comprising at least one of following conditions, the one or more consecutive packets are before a received packet which includes a priority indicator indicating that the received packet is in the middle or is an end of a sequence of prioritized packets, or the one or more consecutive packets are before a received packet which includes a priority indicator indicating that the received packet is in a sequence of prioritized packets comprising only one prioritized packet or is a beginning of a sequence of prioritized packets, in case that a prioritized packet of an end of a sequence of43 prioritized packets before the one or more consecutive packets has not been received at the receiving device.

30. The method according to claim 29, further comprising, waiting for a receipt of the one or more consecutive packets with starting a reordering timer.

31. An apparatus for in-order delivery in a transmitting device, the apparatus comprising: means for including into each packet of a sequence of packets, a priority indicator indicating whether respective packets are prioritized packets a missing of which in the inorder delivery is not allowed to be skipped, and wherein in case that a packet is a prioritized packet, a priority indicator included in the prioritized packet further indicates a sequence of prioritized packets comprising the prioritized packet; and means for transmitting the sequence of packets to a receiving device.

32. An apparatus for in-order delivery in a receiving device, the apparatus comprising: means for trying to receive a sequence of packets from a transmitting device, wherein each packet includes a priority indicator indicating whether respective packets are prioritized packets a missing of which in the in-order delivery is not allowed to be skipped, and wherein in case that a packet is a prioritized packet, a priority indicator included in the prioritized packet further indicates a sequence of prioritized packets comprising the prioritized packet; and means for determining whether a missing of one or more consecutive packets of the sequence of packets is to be skipped based on respective priority indicators of received packets before and / or after the one or more packets in the sequence of packets33. A computer-readable medium having computer program codes embodied thereon which, when executed by a processor, cause the processor to perform the method according to any one of claims 24 and 25 to 30.

34. A computer program product comprising computer programs or instructions which, when executed by a processor, cause the processor to perform the method according to any one of claims 24 and 25 to 30.

Images