Data format for concatenation of packet data units

Abstract

A wireless communication device (10, 100) sends one or more wireless transmissions conveying a sequence of concatenated Packet Data Units, PDUs, to a further wireless communication device (10, 100). Each PDU of the concatenated PDUs has a format comprising a data part and a header part. The data part for conveys at least one Service Data Unit, SDU, and / or at least one SDU segment of an SDU. The header part comprises a sequence number of the concatenated PDU. The sequence number is assigned based on the at least one SDU and / or at least one SDU segment included in the data part.

Description

[0001] Data format for concatenation of Packet Data Units

[0002] Technical Field

[0003] The present invention relates to methods for communication in a wireless communication network and to corresponding devices, systems, and computer programs.

[0004] Background

[0005] In wireless communication networks, e.g., based on the 4G (4th Generation) LTE (Long Term Evolution) or 5G (5th Generation) NR technology as specified by 3GPP (3rd Generation Partnership Project), it is known to utilize various packetized data formats for conveying user plane data.

[0006] By way of example, Fig. 1 schematically illustrates user-plane architecture and protocol layers as utilized in the 5G NR technology. In the architecture of Fig. 1 , a UE (user equipment) is connected over the air, via a radio interface denoted as “Uu”, with a radio access network (RAN), in particular with a radio access node denoted as “gNB”. The gNB may be separated into a distributed unit (DU) and a centralized unit (CU), connected via F1 interface. The gNB is connected to a core network (CN) which includes a user-plane function (UPF). Typically, IP (Internet Protocol) data is transported via an entity denoted as UE-gNB-UPF. The RAN protocol stack between UE and gNB includes a Service Data Adaptation Protocol (SDAP) protocol, for handling mapping of QoS (Quality of Service) flows as established by the UPF to data radio bearers (DRBs) as established by the gNB. A protocol data convergence protocol (PDCP) is, among others, responsible for encryption, integrity protection, handover forwarding, and retransmission. Handovers between gNBs may be handled by an inter-gNB interface denoted as “Xn”. A radio link control (RLC) protocol is, among others, responsible for segmentation of higher layer data, such as PDCP or IP packets, to fit transport blocks (TBs) available on lower layers for over the air transmission on the Uu interface. Retransmissions are based on automated repeat request (ARQ) in acknowledged mode of RLC. A MAC (Medium Access Control) protocol supports scheduling of transmissions over the air, including hybrid automated repeat request (HARQ) functionalities. Modulation and coding and actual physical transmission are handled by physical layer (PHY) entities in the UE and the gNB.

[0007] Concatenation is the process of including multiple higher layer data units, in particular service data units (SDUs) in a packetized data format of a certain protocol layer, e.g., of a packet data unit (PDU). In the LTE technology, concatenation of data, such as IP packets, is implemented on the RLC protocol layer. As a result, PDlls of the RLC layer may include, as SDlls, multiple higher layer PDlls, e.g., PDlls of the PDCP layer, which may in turn include IP packets. Furthermore, the LTE technology also supports segmentation, which means that an RLC PDU may include full SDUs or segmented SDUs. Further, the LTE technology also supports re-segmentation. Resegmentation may be utilized in case that an RLC PDU, that may include multiple SDUs or SDU segments, may need to be retransmitted with a smaller size. In this case, the retransmission is based on re-segmented RLC PDUs, denoted as RLC PDU segments. A special format is used for this PDU type. A segmentation offset is indicated in each PDU segment and utilized for re-assembly of the complete RLC PDU from the RLC PDU segments. The segmentation indicates an offset of the respective RLC PDU segment start with respect to start of the PDU. For SDUs segmented into RLC PDUs and potentially re-segmented into RLC PDU segments, the receiver needs to consider both re-assembly of RLC PDU segments into full RLC PDUs and re-assembly of SDU segments from the full RLC PDUs into full SDUs.

[0008] In the NR technology, concatenation is implemented on the MAC protocol layer, and there is no concatenation on the RLC protocol layer. Accordingly, one RLC PDU includes only one RLC SDU or RLC SDU segment. This also means that no distinction between PDU and PDU segment format is required on the RLC protocol layer. Segmentation offsets may be included in an RLC PDU to indicate the starting point of the SDU segment in relation to the complete SDU.

[0009] The possibility of RLC concatenation as offered by the LTE technology can be considered as being beneficial from a processing point of view, because a need for accesses to memory where the data higher-layer data is stored can be kept at a minimum level. Specifically, it is possible to utilize a single access to the memory per transmission occasion to fetch a chunk of data corresponding to the concatenated SDUs. Since there is no need to intersperse the included SDUs with header fields, this chunk of data can then be directly included into a TB for over-the air transmission. Such efficient transfer of the higher layer data to TBs is however not possible in the NR technology. In the case of the LTE technology, it is however required to define multiple PDU formats and to handle re-assembly of re-segmented RLC PDUs in two steps, i.e. , to first re-assemble RLC PDU segments to RLC PDUs and then re-assemble the included SDU segments to SDUs.

[0010] Accordingly, there is a need for techniques which allow for efficiently communicating concatenated PDUs in a wireless communication network. Summary

[0011] According to an embodiment, a method of controlling wireless communication is provided. According to the method, a wireless communication device sends one or more wireless transmissions conveying a sequence of concatenated PDlls to a further wireless communication device. Each PDU of the concatenated PDlls has a format comprising a data part and a header part. The data part for conveys at least one SDU and / or at least one SDU segment of an SDU. The header part comprises a sequence number of the concatenated PDU. The sequence number is assigned based on the at least one SDU and / or at least one SDU segment included in the data part.

[0012] According to a further embodiment, a method of controlling wireless communication is provided. According to the method, a wireless communication device sends one or more wireless transmissions conveying a sequence of concatenated PDUs to a further wireless communication device. Each PDU of the concatenated PDUs comprises at least one SDU and / or at least one SDU segment of an SDU. Further, the wireless communication device receives a status message from the further wireless communication device. The status message comprises a first field indicating, in terms of a respective sequence number, one or more of the concatenated PDUs for which reception by the further wireless communication device was not successful, and / or a second field indicating, in terms of a respective sequence number, a last one of the concatenated PDUs for which reception by the further wireless communication device was successful. The respective sequence number of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment comprised by the concatenated PDU.

[0013] According to a further embodiment, a method of controlling wireless communication is provided. According to the method, a wireless communication device receives one or more wireless transmissions conveying a sequence of concatenated PDUs from a further wireless communication device. Each PDU of the concatenated PDUs has a format comprising a data part and a header part. The data part for conveys at least one SDU and / or at least one SDU segment of an SDU. The header part comprises a sequence number of the concatenated PDU. The sequence number is assigned based on the at least one SDU and / or at least one SDU segment included in the data part.

[0014] According to a further embodiment, a method of controlling wireless communication is provided. According to the method, a wireless communication device receives one or more wireless transmissions conveying a sequence of concatenated PDlls from a further wireless communication device. Each PDU of the concatenated PDlls comprises at least one SDU, and / or at least one SDU segment of an SDU. Further, the wireless communication device sends a status message to the further wireless communication device. The status message comprises a first field indicating, in terms of a respective sequence number, one or more of the concatenated PDUs for which reception by the wireless communication device was not successful, and / or a second field indicating, in terms of a respective sequence number, a last one of the concatenated PDUs for which reception by the wireless communication device was successful. The respective sequence number of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment comprised by the concatenated PDU.

[0015] According to a further embodiment, a wireless communication device for operation in a wireless communication network is provided. The wireless communication device is configured to send one or more wireless transmissions conveying a sequence of concatenated PDUs to a further wireless communication device. Each PDU of the concatenated PDUs has a format comprising a data part and a header part. The data part for conveys at least one SDU and / or at least one SDU segment of an SDU. The header part comprises a sequence number of the concatenated PDU. The sequence number is assigned based on the at least one SDU and / or at least one SDU segment included in the data part.

[0016] According to a further embodiment, a wireless communication device for operation in a wireless communication network is provided. The wireless communication device comprises at least one processor and a memory. The memory contains instructions executable by said at least one processor, whereby the wireless communication device is operative to send one or more wireless transmissions conveying a sequence of concatenated PDUs to a further wireless communication device. Each PDU of the concatenated PDUs has a format comprising a data part and a header part. The data part for conveys at least one SDU and / or at least one SDU segment of an SDU. The header part comprises a sequence number of the concatenated PDU. The sequence number is assigned based on the at least one SDU and / or at least one SDU segment included in the data part.

[0017] According to a further embodiment, a wireless communication device for operation in a wireless communication network is provided. The wireless communication device is configured to send one or more wireless transmissions conveying a sequence of concatenated PDUs to a further wireless communication device. Each PDU of the concatenated PDUs comprises at least one SDU and / or at least one SDU segment of an SDU. Further, the wireless communication device is configured to receive a status message from the further wireless communication device. The status message comprises a first field indicating, in terms of a respective sequence number, one or more of the concatenated PDlls for which reception by the further wireless communication device was not successful, and / or a second field indicating, in terms of a respective sequence number, a last one of the concatenated PDlls for which reception by the further wireless communication device was successful. The respective sequence number of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment comprised by the concatenated PDU.

[0018] According to a further embodiment, a wireless communication device for operation in a wireless communication network is provided. The wireless communication device comprises at least one processor and a memory. The memory contains instructions executable by said at least one processor, whereby the wireless communication device is operative to send one or more wireless transmissions conveying a sequence of concatenated PDUs to a further wireless communication device. Each PDU of the concatenated PDUs comprises at least one SDU and / or at least one SDU segment of an SDU. Further, the memory contains instructions executable by said at least one processor, whereby the wireless communication device is operative to receive a status message from the further wireless communication device. The status message comprises a first field indicating, in terms of a respective sequence number, one or more of the concatenated PDUs for which reception by the further wireless communication device was not successful, and / or a second field indicating, in terms of a respective sequence number, a last one of the concatenated PDUs for which reception by the further wireless communication device was successful. The respective sequence number of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment comprised by the concatenated PDU.

[0019] According to a further embodiment, a wireless communication device for operation in a wireless communication network is provided. The wireless communication device is configured to receive one or more wireless transmissions conveying a sequence of concatenated PDUs from a further wireless communication device. Each PDU of the concatenated PDUs has a format comprising a data part and a header part. The data part for conveys at least one SDU and / or at least one SDU segment of an SDU. The header part comprises a sequence number of the concatenated PDU. The sequence number is assigned based on the at least one SDU and / or at least one SDU segment included in the data part.

[0020] According to a further embodiment, a wireless communication device for operation in a wireless communication network is provided. The wireless communication device comprises at least one processor and a memory. The memory contains instructions executable by said at least one processor, whereby the wireless communication device is operative to receive one or more wireless transmissions conveying a sequence of concatenated PDlls from a further wireless communication device. Each PDU of the concatenated PDlls has a format comprising a data part and a header part. The data part for conveys at least one SDU and / or at least one SDU segment of an SDU. The header part comprises a sequence number of the concatenated PDU. The sequence number is assigned based on the at least one SDU and / or at least one SDU segment included in the data part.

[0021] According to a further embodiment, a wireless communication device for operation in a wireless communication network is provided. The wireless communication device is configured to receive one or more wireless transmissions conveying a sequence of concatenated PDUs from a further wireless communication device. Each PDU of the concatenated PDUs comprises at least one SDU, and / or at least one SDU segment of an SDU. Further, the wireless communication device is configured to send a status message to the further wireless communication device. The status message comprises a first field indicating, in terms of a respective sequence number, one or more of the concatenated PDUs for which reception by the wireless communication device was not successful, and / or a second field indicating, in terms of a respective sequence number, a last one of the concatenated PDUs for which reception by the wireless communication device was successful. The respective sequence number of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment comprised by the concatenated PDU.

[0022] According to a further embodiment, a wireless communication device for operation in a wireless communication network is provided. The wireless communication device comprises at least one processor and a memory. The memory contains instructions executable by said at least one processor, whereby the wireless communication device is operative to receive one or more wireless transmissions conveying a sequence of concatenated PDUs from a further wireless communication device. Each PDU of the concatenated PDUs comprises at least one SDU, and / or at least one SDU segment of an SDU. Further, the memory contains instructions executable by said at least one processor, whereby the wireless communication device is operative to send a status message to the further wireless communication device. The status message comprises a first field indicating, in terms of a respective sequence number, one or more of the concatenated PDUs for which reception by the wireless communication device was not successful, and / or a second field indicating, in terms of a respective sequence number, a last one of the concatenated PDUs for which reception by the wireless communication device was successful. The respective sequence number of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment comprised by the concatenated PDU.

[0023] According to a further embodiment, a system is provided. The system comprises a first wireless communication device and a second wireless communication device. The first wireless communication device is configured to send wireless transmissions conveying a sequence of concatenated PDUs. Each PDU of the concatenated PDUs has a format comprises a data part for conveying at least one SDU and / or at least one SDU segment of an SDU and a header part comprising a sequence number of the concatenated PDU. The sequence number is assigned based on the at least one SDU and / or at least one SDU segment included in the data part. The second wireless communication device is configured to receive the wireless transmissions from the first wireless communication device.

[0024] According to a further embodiment, a system is provided. The system comprises a first wireless communication device and a second wireless communication device. The first wireless communication device is configured to send one or more wireless transmissions conveying a sequence of concatenated PDUs. Each PDU of the concatenated PDUs comprises at least one SDU and / or at least one SDU segment of an SDU. The second wireless communication device is configured to send a status message to the first wireless communication device. The status message comprising a first field indicating, in terms of a respective sequence number, one or more of the concatenated PDUs for which reception by the second wireless communication device was not successful, and / or a second field indicating, in terms of a respective sequence number, a last one of the concatenated PDUs for which reception by the second wireless communication device was successful. The respective sequence number of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment comprised by the concatenated PDU.

[0025] According to a further embodiment of the invention, a computer program or computer program product is provided, e.g., in the form of a non-transitory storage medium, which comprises program code to be executed by at least one processor of a wireless communication device. Execution of the program code causes the wireless communication device to send one or more wireless transmissions conveying a sequence of concatenated PDUs to a further wireless communication device. Each PDU of the concatenated PDUs has a format comprising a data part and a header part. The data part for conveys at least one SDU and / or at least one SDU segment of an SDU. The header part comprises a sequence number of the concatenated PDU. The sequence number is assigned based on the at least one SDU and / or at least one SDU segment included in the data part. According to a further embodiment of the invention, a computer program or computer program product is provided, e.g., in the form of a non-transitory storage medium, which comprises program code to be executed by at least one processor of a wireless communication device. Execution of the program code causes the wireless communication device to send one or more wireless transmissions conveying a sequence of concatenated PDlls to a further wireless communication device. Each PDU of the concatenated PDlls comprises at least one SDU and / or at least one SDU segment of an SDU. Further, execution of the program code causes the wireless communication device to receive a status message from the further wireless communication device. The status message comprises a first field indicating, in terms of a respective sequence number, one or more of the concatenated PDUs for which reception by the further wireless communication device was not successful, and / or a second field indicating, in terms of a respective sequence number, a last one of the concatenated PDUs for which reception by the further wireless communication device was successful. The respective sequence number of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment comprised by the concatenated PDU.

[0026] According to a further embodiment of the invention, a computer program or computer program product is provided, e.g., in the form of a non-transitory storage medium, which comprises program code to be executed by at least one processor of a wireless communication device. Execution of the program code causes the wireless communication device to receive one or more wireless transmissions conveying a sequence of concatenated PDUs from a further wireless communication device. Each PDU of the concatenated PDUs has a format comprising a data part and a header part. The data part for conveys at least one SDU and / or at least one SDU segment of an SDU. The header part comprises a sequence number of the concatenated PDU. The sequence number is assigned based on the at least one SDU and / or at least one SDU segment included in the data part.

[0027] According to a further embodiment of the invention, a computer program or computer program product is provided, e.g., in the form of a non-transitory storage medium, which comprises program code to be executed by at least one processor of a wireless communication device. Execution of the program code causes the wireless communication device to receive one or more wireless transmissions conveying a sequence of concatenated PDUs from a further wireless communication device. Each PDU of the concatenated PDUs comprises at least one SDU, and / or at least one SDU segment of an SDU. Further, execution of the program code causes the wireless communication device to send a status message to the further wireless communication device. The status message comprises a first field indicating, in terms of a respective sequence number, one or more of the concatenated PDlls for which reception by the wireless communication device was not successful, and / or a second field indicating, in terms of a respective sequence number, a last one of the concatenated PDlls for which reception by the wireless communication device was successful. The respective sequence number of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment comprised by the concatenated PDU.

[0028] Details of such embodiments and further embodiments will be apparent from the following detailed description of embodiments.

[0029] Brief Description of the Drawings

[0030] Fig. 1 schematically illustrates a user-plane protocol architecture as utilized in the NR technology.

[0031] Fig. 2 schematically illustrates a wireless communication network according to an embodiment of the present disclosure.

[0032] Fig. 3A schematically illustrates an example of RLC concatenation and segmentation of SDUs according to an embodiment of the present disclosure.

[0033] Fig. 3B schematically illustrates an example of re-segmentation of SDUs of the example of Fig. 3A.

[0034] Fig. 4A schematically illustrates a further example of RLC concatenation and segmentation of SDUs according to an embodiment of the present disclosure.

[0035] Fig. 4B schematically illustrates an example of re-segmentation of SDUs of the example of Fig. 4A.

[0036] Fig. 5A schematically illustrates a further example of RLC concatenation and segmentation of SDUs according to an embodiment of the present disclosure.

[0037] Fig. 5B schematically illustrates an example of re-segmentation of SDUs of the example of Fig. 5A. Fig. 6 schematically illustrates a data PDU format according to an embodiment of the present disclosure.

[0038] Fig. 7 schematically illustrates a control PDU format according to an embodiment of the present disclosure.

[0039] Fig. 8 shows a flowchart for schematically illustrating a method according to an embodiment of the present disclosure.

[0040] Fig. 9 shows a flowchart for schematically illustrating a further method according to an embodiment of the present disclosure.

[0041] Fig. 10 shows a flowchart for schematically illustrating a further method according to an embodiment of the present disclosure.

[0042] Fig. 11 shows a flowchart for schematically illustrating a further method according to an embodiment of the present disclosure.

[0043] Fig. 12 schematically illustrates structures of a wireless device according to an embodiment of the present disclosure.

[0044] Fig. 13 schematically illustrates structures of a network node according to an embodiment of the present disclosure.

[0045] Fig. 14 schematically illustrates interaction of a host and a wireless device according to an embodiment of the present disclosure.

[0046] Detailed Description

[0047] In the following, concepts in accordance with exemplary embodiments of the invention will be explained in more detail and with reference to the accompanying drawings. The illustrated embodiments relate to wireless communication in a wireless communication network, utilizing PDUs conveyed by one or more wireless transmissions from a transmitting wireless communication device to a receiving wireless communication device. The wireless communication network may be based on a future 6G (6th Generation) technology. However, other technologies could be used as well, e.g., the 4G LTE technology or the 5G NR technology specified by 3GPP. The transmitting wireless communication device may be a radio access node of the wireless communication network, such as a gNB of the 5G NR technology, an eNB of the 4G LTE technology, or a corresponding radio access node of a 6G technology, while the receiving wireless communication device may correspond to a UE. Accordingly, the wireless transmission(s) may correspond to downlink (DL) transmissions from the network to the UE. It is however noted that in some scenarios the transmitting wireless communication device could correspond to a UE, while the receiving wireless communication device could correspond to a radio access node of the wireless communication network, such as a gNB of the 5G NR technology, an eNB of the 4G LTE technology, or a corresponding radio access node of a 6G technology. Accordingly, the wireless transmissions could also correspond to uplink (UL) wireless transmissions from a UE to the network. Further, in some scenarios the transmitting wireless communication device could correspond to a UE, while the receiving wireless communication device could correspond to another UE. Accordingly, the wireless transmissions could also correspond to sidelink (SL) wireless transmissions or similar device- to-device transmissions between UEs.

[0048] In the illustrated concepts, concatenation of PDUs conveying one or more SDUs or SDU segments may be supported in an efficient manner by utilizing a single PDU format which can be applied in a versatile manner. More specifically, the concatenated PDUs may be RLC PDUs and may carry one or more higher layer SDUs or one or more segments of such higher layer SDUs. The higher layer SDUs may for example correspond to PDCP PDUs or IP packets. The versatile PDU format is based on using a sequence number (SN) which is assigned based on the SDU(s) or SDU segment(s) conveyed by the PDU. The assignment of the SN may be performed in such a way that a new SN is assigned whenever a new PDU in the sequence of concatenated PDUs at least partly includes, i.e., includes at least a segment of a new SDU, i.e., of an SDU which was not partly or completely included in a previous PDU of the sequence. Further, a segmentation offset (SO) may be defined for each PDU. The SO may be defined with respect to a reference SDU. The reference SDU may correspond to an SDUs of which at least an SDU segment is included in the PDU. More specifically, if the concatenated PDUs convey a sequence of SDUs, the reference SDU may correspond to the first SDU of the sequence of SDUs, of which at least an SDU segment is included in the considered concatenated PDU.

[0049] As a result, the SDU data may be efficiently included in the concatenated PDUs, either as complete SDUs or as SDU segments, without requiring addition of header data or similar assistance information between the SDUs or SDU segments. Further, the SDUs and SDU segments may be efficiently re-assembled from the data conveyed by the concatenated PDUs, by considering the SNs and, if present, the SO. As a result, quick processing of the wireless transmissions in the transmitting wireless communication device may be achieved, without adding excessive requirements on the processing of the wireless transmissions by the receiving wireless communication device. Such quick processing may in turn help in achieving low latency of data transfers and improved user experience for a service which is based on such data transfers. Further, the quick processing may also contribute to high energy efficiency of the transmitting wireless communication device and / or of the receiving wireless communication device.

[0050] Fig. 2 illustrates exemplary structures of the wireless communication network. In particular, Fig. 2 shows UEs 10 within and in vicinity of a cell 110 which is served by an access node 100 of the wireless communication network. Here, it is noted that the wireless communication network may actually include a plurality of access nodes 100 that may serve a number of cells within the coverage area of the wireless communication network. The access node 100 may for example correspond to a radio access node of a future 6G technology, an eNB of the LTE technology, or to a gNB of the NR technology.

[0051] The access nodes 100 may be regarded as being part of an RAN of the wireless communication network. Further, Fig. 2 schematically illustrates a CN (Core Network) 210 of the wireless communication network. In Fig. 2, the CN 210 is illustrated as including a GW (gateway) 220 and one or more control node(s) 240. The GW 220 may be responsible for handling user plane data traffic of the UEs 10, e.g., by forwarding user plane data traffic from a UE 10 to a network destination or by forwarding user plane data traffic from a network source to a UE 10. Here, the network destination may correspond to another UE 10, to an internal node of the wireless communication network, or to an external node which is connected to the wireless communication network. Similarly, the network source may correspond to another UE 10, to an internal node of the wireless communication network, or to an external node which is connected to the wireless communication network. The GW 220 may for example correspond to a UPF (User Plane Function) of the 5G Core (EGC) or to an SGW (Serving Gateway) or PGW (Packet Data Gateway) of the 4G EPC (Evolved Packet Core), or to corresponding nodes of a 6G CN. The control node(s) 240 may for example be used for controlling the user data traffic, e.g., by providing control data to the access node 100, the GW 220, and / or to the UE 10.

[0052] As illustrated by double-headed arrows, the access node 100 may send DL wireless transmissions to at least some of the UEs 10, and some of the UEs 10 may send UL wireless transmissions to the access node 100. Further, SL wireless transmissions could be performed directly between two or more of the UEs, e.g., for setting up a relay-based connection to the access node 100. Accordingly, the DL wireless transmissions, UL wireless transmissions, and / or SL wireless transmissions may be used on various kinds of wireless links, including wireless links between UE 10 and access node 100, direct wireless links between UEs, and relay wireless links between a remote UE 10, via a relay UE 10, and the access node 100. The DL wireless transmissions, UL wireless transmissions, and / or SL wireless transmissions may be used to provide various kinds of services to the UEs 10, e.g., a voice service, a multimedia service, or some other data service. Such services may be hosted in the CN 210, e.g., by a corresponding network node. By way of example, Fig. 2 illustrates an application service platform 250 provided in the CN 210. Further, such services may be hosted externally, e.g., by an AF (application function) connected to the CN 210. By way of example, Fig. 2 illustrates one or more application servers 300 connected to the CN 210. The application server(s) 300 could for example connect through the Internet or some other wide area communication network to the CN 210. The application service platform 250 may be based on a server or a cloud computing system and be hosted by one or more host computers. Similarly, the application server(s) 300 may be based on a server or a cloud computing system and be hosted by one or more host computers. The application server(s) 300 may include or be associated with one or more AFs that enable interaction with the CN 210 to provide one or more services to the UEs 10, corresponding to one or more applications. These services or applications may generate the user data traffic conveyed by the DL transmissions and / or the UL transmissions. Accordingly, the application server(s) 300 may include or correspond to the above-mentioned network destination and / or network source for the user data traffic. In the respective UE 10, such service may be based on an application (or shortly “app”) which is executed on the UE 10. Such application may be pre-installed or installed by the user. Such application may generate at least a part of the user plane data traffic between the UEs 10 and the access node 100.

[0053] In accordance with the illustrated concepts, concatenation of PDUs may be utilized on at least some of the links in the wireless communication network. In the following, the concatenation and optional segmentation of SDUs conveyed by the concatenated PDUs will be explained in more detail by referring to more specific examples. As can be seen, the illustrated concepts may be utilized to enable concatenation of PDUs and segmentation of SDUs conveyed by the concatenated PDUs in an efficient manner, using a single PDU format. The concatenated PDUs may correspond to RLC PDUs. It is however noted that the illustrated concepts could be applied in a corresponding manner also to other protocol layers, e.g., to PDUs of the MAC protocol layer. To illustrate the concatenation and segmentation principles of the illustrated concepts, Fig. 3A illustrates an exemplary sequency of SDlls, denoted as SDU A, SDU B, SDU C, and SDU D. For transmitting SDU data on a wireless link, a part of the SDU data, including full SDUs (in the illustrated example SDU B and SDU C) and segments of SDUs (in the illustrated example a segment of SDU A and a segment of SDU D), are included in a PDU. In the illustration, the part of the SDU data which is included in the PDU is illustrated by a broken line box. The PDU is assumed to be based on a format with a header part and a data part. The SDU data are included in the data part of the PDU. In the example of Fig. 3A, the first SDU (SDU A) and the last SDU (SDU D) are thus only included partially in the data part of the PDU. As further illustrated, the SO of the PDU is defined to extend from the start of the first SDU (SDU A) to the beginning of the SDU data in the data part of the PDU, e.g., in terms of a number or data bytes. In this example, SDU A thus constitutes the reference SDU for the PDU (because SDU A is the first SDU of the sequence of which at least a part is included in the PDU).

[0054] An alternative example of segmenting the SDU data is illustrated in Fig. 3B. The example of Fig. 3B assumes that sequence of multiple concatenated PDUs is utilized for conveying the SDU data. The parts of SDU data respectively included in the concatenated SDUs are again illustrated by broken line boxes. As can be seen, for a first PDU of the sequence of concatenated PDUs, the data part of the PDU includes a segment of SDU A and a segment of SDU B. For a second PDU of the sequence of concatenated PDUs, the data part of the PDU includes a segment of SDU B and SDU C (completely). For a third PDU of the sequence of concatenated PDUs, the data part of the PDU includes SDU D (completely). The segmentation of Fig. 3B may for example be a result of re-segmenting the SDU data. Specifically, the segmentation of Fig. 3A could be used in an initial transmission of the SDU data, while the segmentation of Fig. 3B is used in a retransmission of the SDU data. For the retransmission, the selection of SDU A as the reference SDU is maintained, thereby facilitating re-assembly of the SDUs from the segments by the receiving wireless communication device, irrespective of successful reception of the SDU data by the receiving wireless communication device being based on the initial transmission or on a retransmission.

[0055] As mentioned above, each PDU of the concatenated PDUs is also assigned an SN. In the illustrated examples, it is assumed that the SN is included in the header part of PDU. The assignment of the SNs to the PDUs may such that the SN is increased when the PDU contains a new SDU or segment of a new SDU, which was not part of the preceding PDU of the sequence. Then, for this PDU the first SDU of the sequence of which at least a part is included in the PDU may be selected as the reference SDU for this PDU and SN. Here, it is noted that the reference SDU does not necessarily correspond to the new SDU which caused the increase of the SN. In the example of Fig. 3A, the reference SDU is SDU A. An increased SN would be assigned when a subsequent PDU includes SDU E (i.e., the SDU following SDU D in the sequence, not shown in Fig. 3A). In this case, if no segment of SDU D is included in the subsequent PDU, the reference SDU for this subsequent PDU would be SDU E. If in turn a segment of SDU D is included in the subsequent PDU, the reference SDU for the subsequent PDU would be SDU D.

[0056] As mentioned above, an SO may be assigned to each concatenated PDU. Similar to the SN, the SO may be included in the header part of the PDU. The SO may be defined with respect to the start of the reference SDU. Specifically, the SO may indicate the offset, e.g., in terms of a number of bytes, from the start of the reference SDU to the start of the SDU data in the PDU, i.e., the first byte of the reference SDU or of a subsequent SDU in the data part of the PDU. Due to the above way of defining the SO, the SO always has a positive value. In the examples of Fig. 3A, the SO refers to the start of SDU A. Based on the SO, the receiving wireless communication device may identify to which position within the SDU received SDU segments belong.

[0057] If the transmitting wireless communication retransmits parts of the PDU or the entire PDU and needs to reduce the transmission block size, re-segmentation of the SDU data may be performed, e.g., as illustrated in Fig. 3B. For such retransmission(s), the same SN as for the initial transmission may be maintained, thereby facilitating re-assembly of the SDUs by the receiving wireless communication device. Such re-segmentation for retransmission may result situations where no part of the reference SDU is included in the PDU, e.g., like in the second and third PDU of Fig. 3B, where no part of SDU A (which is maintained as the reference SDU) is included in the PDU. Even if the receiving wireless communication device receives SDU segments out of order, e.g., because during the retransmission process a reordering occurs on lower protocol layers, the receiving wireless communication device can identify based on the SO that one or more previous SDU segments are still to be received.

[0058] For identifying a length of the overall PDU, one or more length fields may be utilized on lower protocol layers. For example, if the PDU is an RLC PDU, such length field(s) could be provided on the MAC protocol layer. For identifying the lengths of the SDU(s) or SDU segment(s) included in the PDU, one or more length fields associated with the SDU(s) or SDU segment(s) may be included in the header part of the PDU. If the number of SDUs or SDU segments included in the PDU is N, N-1 length fields may be included in the header part of the PDU. For the last SDU or SDU segment included in the PDU, such length field may be omitted because the end of this SDU or SDU segment corresponds to the end of the data part of the PDU. The length field(s) included in the header part of the PDU may facilitate re-assembly of the SDlls by the receiving wireless communication device. In some scenarios, also one or more indicators may be included in the header part of the PDU to indicate whether a first byte of an SDU or a last byte of an SDU is included in the PDU. Such indicator may for example be implemented as framing / segmentation indicator (FI / SI) bits, similar to the LTE and NR technology. For example, a first indicator bit could indicate whether a first byte of a conveyed SDU is present in the PDU and a second indicator bit could indicate whether a last byte of a conveyed SDU is present in the PDU.

[0059] With reference to Figs. 4A and 4B, it is further illustrated how the illustrated concepts can be applied to segmentation of a single SDU, in this example denoted as SDU A. In the illustrated example, the single SDU (SDU A) also constitutes the reference SDU. All PDUs carrying SDU data of the single SDU are assigned the same SN. The SO is defined with respect to the start of SDU A and, irrespective of the specific segmentation, represents the offset between the start of SDU A and the start of the SDU data in the data part of the respective PDU. The SDU data conveyed in the data parts of the PDUs are indicated by respective broken line boxes. Similar to the example of Figs. 3A and 3B, the segmentation of Fig. 4A may correspond to an initial transmission, and the segmentation of Fig. 4B may correspond to a retransmission. As can be seen, in the example of Fig. 4A, a first segment of the SDU is conveyed in a first PDU, and a second segment of the SDU is conveyed in a second PDU. The same SN is assigned to both SNs. For the first PDU, the SO is zero, because the start of the reference SDU is in the PDU. For the second PDU, the SO corresponds to the offset between the start of the SDU and the beginning of the SDU data in the second PDU.

[0060] The example of Fig. 4B may correspond to a situation where the SDU data in the second PDU in the example of Fig. 4A is retransmitted. Accordingly, the second segment in the example of Fig. 4A is re-segmented for retransmission, such that a third PDU includes a third segment of the SDU, a fourth PDU includes a fourth segment of the SDU, and a fifth PDU includes a fifth segment of the SDU. The third segment, fourth segment, and fifth segment in turn constitute segments of the second segment in the example of Fig. 4A.

[0061] In the example of Figs. 4A and 4B, usage of the same SN for all PDUs enables the receiving wireless communication device to efficiently re-assemble the SDUs from the segments. For example, if the receiving wireless communication device successfully received the first segment with the first PDU and the third segment, fourth segment, and fifth segment with the third PDU, fourth PDU, and fifth PDU, the receiving wireless communication device can re- assemble the complete SDU from these segments. This is facilitated by the SOs respectively indicated by the PDlls.

[0062] Figs. 5A and 5B illustrate an example where reference SDU differs between some PDUs of the sequence of concatenated PDUs. In the example of Figs. 5A and 5B, the concatenated PDUs are used for conveying a sequence of SDUs, denoted as SDU A, SDU B, SDU C, SDU D, and SDU E. Again, the SDU data conveyed in the data parts of the PDUs are indicated by respective broken line boxes. In the example of Fig. 5A, a first PDU of the sequence includes SDU A (completely) and a first segment of SDU B. A second PDU of the sequence includes a second segment of SDU B (corresponding to the remaining SDU data of SDU B, which were not included in the first PDU) and a first segment of SDU C. A third PDU of the sequence includes a second segment of SDU C (corresponding to the remaining SDU data of SDU C, which were not included in the second PDU) and a first segment of SDU D. A fourth PDU of the sequence includes a second segment of SDU C (corresponding to the remaining SDU data of SDU C, which were not included in the third PDU) and SDU E (completely). In accordance with the above principles of assigning the SN to PDUs, the first PDU is assigned SNO, the second PDU is assigned SN1 , which is increased from SNO, the third PDU is assigned SN2, which is increased from SN1 , and the fourth PDU is assigned SN3, which is increased from SN2. The reference SDU for the first PDU and SNO is SDU A. Since the start of SDU A is in the first PDU, the SO is zero. The reference SDU for the second PDU and SN1 is SDU B. The SO for the second PDU is defined from the start of SDU B to the start of the SDU data of SDU B in the second PDU. The reference SDU for the third PDU and SN2 is SDU C. The SO for the third PDU is defined from the start of SDU C to the start of the SDU data of SDU C in the third PDU. The reference SDU for the fourth PDU and SN3 is SDU D. The SO for the fourth PDU is defined from the start of SDU D to the start of the SDU data of SDU D in the fourth PDU.

[0063] Similar to the example of Figs. 3A and 3B, and the example of Figs. 4A and 4B, the segmentation of Fig. 5A may correspond to an initial transmission, and the segmentation of Fig. 5B may correspond to a retransmission. Specifically, the segmentation of Fig. 5 may be applied when the initial transmission of the second PDU (with SN 1 ) is not successfully received by the receiving wireless communication device, causing retransmission of the part of the SDU data of SDU B and of SDU C which were included in the second PDU. Accordingly, the SDU data are re-segmented for retransmission, such that a fifth PDU includes a third segment of SDU C and a sixth PDU includes a third segment of SDU B and a fourth segment of SDU C. The third segment and fourth segment of SDU C together correspond to the second segment of SDU C, for which reception was not successful in the initial transmission based on the second PDU. The third segment of SDU B corresponds to the second segment of SDU B, for which reception was not successful in the initial transmission based on the second PDU. As can be seen, the SN number of the second PDU, i.e., SN1 , is maintained for the fifth PDU and the sixth PDU. Similarly, the reference SDUs are maintained, i.e., SDU B is kept as the reference SDU for the fifth PDU and for the sixth PDU.

[0064] In the example of Figs. 5A and 5B, the retransmission may be managed in the following ways: The receiving wireless communication device may notice the gap between the SNs of successfully received PDUs, i.e., that a PDU with SNO was successfully received, a PDU with SN2 was successfully received, but that a PDU with SN1 is missing. In an un-acknowledged mode, a re-assembly timer may be triggered for outstanding SDU segments, e.g., upon successful reception of subsequent SDUs or SDU segments to the outstanding SDU segment. Upon expiry of the re-assembly timer, out-of-order delivery of subsequent complete SDUs may be triggered, i.e., of SDU D and SDU E. In an acknowledged mode, the receiving wireless communication device may perform status reporting to indicate the missing SDU data, and based on this status reporting, the transmitting wireless communication device may retransmit the second PDU (with SN1). Possible details of such status reporting are further explained below.

[0065] In the example of Figs. 5A and 5B, the SDU data in the second PDU is re-segmented in for the retransmission. Both PDUs of the retransmission, i.e., the fifth PDU and the sixth PDU have the same reference SDU (SDU B) and the same SN as the second PDU. As illustrated, the re-segmented SDU data may be received out-of-order: With the fifth PDU, the receiving wireless communication device may first receive the third segment of SDU C and then later receive the fourth segment of SDU C with the sixth PDU, even though the fourth segment of SDU C is precedes the third segment of SDU C in the original order of the SDU data. Based on the SO of the fifth PDU indicating an offset that goes beyond the length of the SDU B segment within the PDU (in the illustrated example a length of zero), the receiving wireless communication device may derive that the reference SDU of the received fifth PDU is not included, and delivery of SDU B is not complete. The receiving wireless communication device may thus deduce that SDU order is not yet established in the received SDU data. Furthermore, the SO in the header of the fifth PDU a length indicator that points to the end of SDU A in the second PDU allows the receiving wireless communication device to place the byte of received SDU data at an appropriate position in its memory, so that subsequently received SDU data of SDU can fit in between. Accordingly, re-segmentation re-assembly may be performed without increasing memory fragmentation at the receiving wireless communication device. Fig. 6 schematically illustrates an example of a data PDU format that may be utilized for implementing the illustrated concepts. As illustrated, the PDU format includes a header part with various fields. Among these fields, a field denoted as “D / C” may indicate whether the PDU is a data PDU (“D”) or a control PDU (“C”). In the illustrated example, the D / C field would indicate that the PDU is a data PDU. Further, a polling bit “P” may be included. A field denoted as “SI” may include the above-mentioned SI indicator. Further, reserved bits, denoted by “R”, may be included. A further field, denoted as “SN” includes the SN of the PDU, which is assigned as explained above. Specifically, as mentioned above, the SN of the PDU may be assigned in accordance with the reference SDU, such that PDUs having the same reference SDU also have the same SN.

[0066] As further illustrated, the header part is provided with a field denoted as “SO”, which includes the above-mentioned SO. Here, it is noted that the SO field could be always included or be omitted in certain cases, e.g., when reference SDU starts at O, i.e. , at the beginning of the data part of the PDU. In the latter case a bit in the PDU header may include an indication that the SO field is not included. Such indicator could for example be implemented by one of the reserved bits R. If SO field is included, the SO indicated by the SO field refers to the start of the reference SDU. Further, the header part may include extension fields, denoted by “E” to indicate that a respective length indicator field, denoted by “LI” follows. Such LI fields may be included in a selective manner when the data part of the PDU includes multiple SDUs or SDU segments, with each LI field including a length indicator for a corresponding SDU or SDU segment in the data part.

[0067] When for example considering the second PDU of the example of Figs. 5A and 5B, the header fields could be populated as follows: SI = 11 , indicating that the data part includes neither the first byte of the first SDU, nor the last byte of the last SDU; SN = 1 ; SO = number bytes of SDU B not included in PDU 1 ; E = 1 ; and one LI field indicating the length of the SDU data of SDU B included in the data part. The data part would then include part of the SDU data of SDU, i.e., a segment of SDU B, an part of the SDU data of SDU C, i.e., a segment of SDU C.

[0068] Fig. 7 schematically illustrates an example of a control PDU format which may be used for the above-mentioned status reporting from the receiving wireless communication device to the transmitting wireless communication device. Such status reporting may in particular include feedback on successful reception of concatenated PDUs by the receiving wireless communication device. As illustrated, the control PDU includes various fields. Among these fields, a field denoted as “D / C” may indicate whether the PDU is a data PDU (“D”) or a control PDU (“C”). In the illustrated example, the D / C field would indicate that the PDU is a control PDU. A further field denoted as “CPT” indicates a control PDU type. In the illustrated example, the CPT field would indicate that the control PDU type is “status”, i.e. , used for status reporting. A field denoted as “ACK_SN” includes an acknowledgement SN, indicating the SN following the highest SN of successfully received data PDUs, excluding SNs of data PDUs which are negatively acknowledged by optionally included fields denoted as “NACK_SN” and “NACK_range”. These SNs are assigned in accordance with the illustrated concepts, based on the SDU(s) or SDU segments conveyed by the data PDUs. The optional inclusion of the latter fields is indicated by an extension field “E1”. The NACK_SN field indicates the SN of a data PDUs for which reception was yet not successful. Here, it is again noted that this SN are assigned in accordance with the illustrated concepts, based on the SDU(s) or SDU segments conveyed by the data PDU. Further extension field “E2” and “E3” may respectively indicate optional inclusion of fields denoted as “SOstart” and “SOend”. The latter fields may indicate a range of bytes missing from the data PDU corresponding to the SN indicated by the NACK_SN field. For example, the SOstart field and SOend fields may respectively indicate start and end of the byte range missing from the data PDU with respect to the start of the reference SDU of the data PDU. Similar to the SO of the illustrated concepts, also the values indicated by the SO start field and the SOend field may thus indicate an offset with respect to the start of the reference SDU. If the reference SDU is not yet known to the receiving wireless communication device, e.g., because the no data PDU indicating the SO and reference SDU was received yet, default values for SOstart and SOend may be applied, e.g., SOstart = 0 and SOend = length of the data part of the PDU, can be utilized. A further extension field, denoted by “E4”, may indicate optional inclusion of a field denoted as “NACK range”. The NACK range field may indicate whether a number of PDUs with SNs including the value of NACK_SN are considered lost.

[0069] When for example considering a status report after the fourth PDU of the example of Figs. 5A and 5B, the fields of the control PDU could be populated as follows: ACK_SN = 4; E1 = 1 ; NACK_SN = 1 ; E2 = 0; E3 = 0, E4 = 0, indicating that the data PDU with SN1 is considered lost, as no part of it was successfully received. After receiving the fifth PDU, with the retransmission of a part of the SDU data of SDU C, the fields would in turn be populated as follows: ACK_SN = 4; E1 = 1 ; NACK_SN = 1 ; E2 = 0; E3 = 1 ; E4 = 0. SOstart = 0 (default as the SO of the reference SDU within the PDU is not known); SOend = the received SO for reference SDU B, as indicated by the fifth PDU. It is noted that when implementing the concatenation of the illustrated concepts of the RLC protocol layer, the PDU formats of Figs. 6 and 7 may correspond to RLC PDU formats.

[0070] Fig. 8 shows a flowchart for illustrating a method, which may be utilized for implementing the illustrated concepts. The method of Fig. 8 may be used for implementing the illustrated concepts in a wireless communication device which wirelessly communicates with a further wireless communication device. The wireless communication device may for example correspond to a network node, e.g., to the above-mentioned access node 100, or to a UE, e.g., to any of the above-mentioned UEs 10. If the wireless communication device is a network node, such as the above-mentioned access node 100, the further wireless communication device may correspond to a UE, such as the any of the above-mentioned UEs 10. If the wireless communication device is a UE, such as the any of the above-mentioned UEs 10, the further wireless communication device may be a network node, such as the above-mentioned access node 100, or another UE, such as any of the above-mentioned UEs 10.

[0071] If a processor-based implementation of the wireless communication device is used, at least some of the steps of the method of Fig. 8 may be performed and / or controlled by one or more processors of the wireless communication device. Such wireless communication device may also include a memory storing program code for implementing at least some of the below described functionalities or steps of the method of Fig. 8.

[0072] At step 810, the wireless communication device may get data of one or more SDU(s), i.e., SDU data, to be transmitted to the further wireless communication device. Getting the date of the one or more SDU(s) may involve accessing a memory storing the data. This may be accomplished in such a way that data which can be conveyed in a single wireless transmission is fetched with a single access operation from the memory. This may in some cases also involve fetching only segments of one or more of the SDU(s) from the memory or fetching SDU data of multiple SDUs or SDU segments in a single access operation from the memory.

[0073] At step 820, the wireless communication device sends one or more wireless transmissions conveying a sequence of concatenated PDUs to the further wireless communication device. Each PDU of the concatenated PDUs has a format including a data part and a header part. The data part is for conveying at least one SDU and / or at least one SDU segment of an SDU, e.g., corresponding to the SDU data from step 810. The data part may thus include the SDU data so that the SDU data can be conveyed by means of the wireless transmission / s) to the further wireless communication device. The header part includes an SN of the concatenated PDU. The SN is assigned based on the at least one SDU and / or at least one SDU segment included in the data part. Fig. 6 shows an example of a corresponding PDU format. The concatenated PDlls may correspond to RLC PDlls.

[0074] In some scenarios, the header part further includes an SO defined with respect to a reference SDU. Typically, at least an SDU segment of the reference SDU is conveyed in the data part of the concatenated PDU. However, in some cases it could also occur that no segment of the reference SDU is conveyed in the concatenated PDU, e.g., if the concatenated PDU corresponds to a retransmission. For such retransmissions, the SN and reference SDU may be maintained from the initial transmission of the SDU data.

[0075] The reference SDU may be specified individually for each concatenated PDU. For example, if the data parts of the sequence of concatenated PDUs convey a sequence of SDUs, the reference SDU may correspond to the first SDU of the sequence of SDUs, of which at least an SDU segment is included in the data part of the concatenated PDU.

[0076] In some scenarios, the SO could also be omitted. For example, for at least one of the concatenated PDUs the SO could not be included in the header part of the PDU, e.g., in response to a start of the reference SDU being included in the data part of the concatenated PDU. In some scenarios, for the at least one of the concatenated PDUs, the header part could further include an indicator indicating that the SO is not included in the header part.

[0077] The SO may refer to a start of the reference SDU. More specifically, the SO may indicate a number of bytes from the start of the reference SDU to a first SDU byte in the data part of the concatenated PDU.

[0078] In some scenarios, the header part may further include or more length indicators indicating a length of a respective SDU within the data part of the concatenated PDU, e.g., as explained for the LI fields in the data format of Fig. 6. Such length indicator(s) may be selectively included in response to the data part of the concatenated PDU conveying data of multiple SDUs. The inclusion of the length indicator(s) may be indicated by an extension indicator preceding the respective length indicator.

[0079] The assignment of the SNs to the concatenated PDUs may be such that, for each concatenated PDU, the SN is assigned based on whether the data part of the concatenated PDU includes at least an SDU segment of a new SDU of the one or more SDUs. Here, the SDU is considered a new SDU if the data part of a previous concatenated PDU of the sequence of concatenated PDUs does not include a segment of this SDU. This may involve that, in response to the data part of the concatenated PDU including at least an SDU segment of a new SDU, the SN is incremented with respect to the SN of the previous concatenated PDU of the sequence of concatenated PDUs. This incrementation may for example involve incrementing the SN by one, but other step sizes could be used as well. It is also noted that for a first concatenated PDU of the sequence, a predefined initial value of the SN may be assigned, such as zero. In response to the data part of the PDU not including at least an SDU segment of a new SDU, the SN of the concatenated PDU may in turn be maintained from the previous concatenated PDU of the sequence of concatenated PDUs.

[0080] In some scenarios, if the sequence of concatenated PDUs includes a first concatenated PDU and a subsequent second concatenated PDU, the data part of the first concatenated PDU may include at least an SDU segment of a first SDU while the data part of the second concatenated PDU includes a further SDU segment of the first SDU. Corresponding examples are described in connection with Fig. 3B, 4A, 4B, 5A, and 5B. Further, if the sequence of concatenated PDUs includes a first concatenated PDU and a subsequent second concatenated PDU, the data part of the first concatenated PDU could include at least an SDU segment of a first SDU while the data part of the second concatenated PDU includes a further SDU segment of the first SDU and at least an SDU segment of a second SDU. Corresponding examples are described in connection with Fig. 3B, 5A, and 5B.

[0081] In some scenarios, the wireless communication device may expect feedback concerning reception of the concatenated PDUs. In particular, for each of the concatenated PDUs, the wireless communication device may expect feedback concerning reception of the concatenated PDU by the further wireless communication device. If reception of the concatenated PDU was successful, the feedback may acknowledge successful reception based on the SN of the successfully received concatenated PDU. This may be accomplished based on a format which includes an acknowledgment SN to identify the SN of the at least one successfully received concatenated PDU, e.g., as explained in connection with the ACK_SN field of Fig. 7. For example, the feedback could include a value of ACK_SN = SN* + 1 , where SN* denotes the highest SN of the successfully received SNs. In addition or as an alternative, the feedback could indicate unsuccessful reception of at least one of the concatenated PDUs based on a format including a negative acknowledgment SN to identify the sequence number of the at least one unsuccessfully received concatenated PDU, e.g., as explained in connection with the NACK_SN field of Fig. 7. Further, the feedback could indicate unsuccessful reception of at least one of the concatenated PDUs based on a format including a negative acknowledgment SN and a negative acknowledgment SN range to identify the SNs of the at least one unsuccessfully received concatenated PDU, e.g., as explained in connection with the NACK_SN and NACK range fields of Fig. 7. Further, the feedback could indicate unsuccessful reception of an SDU segment conveyed by one of the concatenated PDlls based on a format including a negative acknowledgment SN to identify the concatenated PDU, a first SO to identify a start of the unsuccessfully received SDU segment and a second SO to identify an end of the unsuccessfully received SDU segment, e.g., as explained in connection with the NACK_SN, SOstart, and SEend fields of Fig. 7. Such first SO and the second SO may be defined with respect to a reference SDU of the identified concatenated PDU, e.g., the above- mentioned reference SDU used for determination of the SO indicated in the header part of the concatenated PDU. The first SO may indicate a number of bytes from the start of the reference SDU to a first SDU byte of the unsuccessfully received SDU segment and the second SO may indicate a number of bytes from the start of the reference SDU to a last SDU byte of the unsuccessfully received SDU segment. The feedback may for example be included in a control PDU, e.g., using a format as illustrated in Fig. 7. Based on the feedback, the wireless communication device may control retransmission of at least one SDU and / or at least one SDU segment of one or more SDUs conveyed by the data parts of the concatenated PDUs.

[0082] Fig. 9 shows a flowchart for illustrating a method, which may be utilized for implementing the illustrated concepts. The method of Fig. 9 may be used for implementing the illustrated concepts in a wireless communication device which wirelessly communicates with a further wireless communication device. The wireless communication device may for example correspond to a network node, e.g., to the above-mentioned access node 100, or to a UE, e.g., to any of the above-mentioned UEs 10. If the wireless communication device is a network node, such as the above-mentioned access node 100, the further wireless communication device may correspond to a UE, such as the any of the above-mentioned UEs 10. If the wireless communication device is a UE, such as the any of the above-mentioned UEs 10, the further wireless communication device may be a network node, such as the above-mentioned access node 100, or another UE, such as any of the above-mentioned UEs 10.

[0083] If a processor-based implementation of the wireless communication device is used, at least some of the steps of the method of Fig. 9 may be performed and / or controlled by one or more processors of the wireless communication device. Such wireless communication device may also include a memory storing program code for implementing at least some of the below described functionalities or steps of the method of Fig. 9.

[0084] At step 910, the wireless communication device may get data of one or more SDU(s), i.e., SDU data, to be transmitted to the further wireless communication device. Getting the date of the one or more SDU(s) may involve accessing a memory storing the data. This may be accomplished in such a way that data which can be conveyed in a single wireless transmission is fetched with a single access operation from the memory. This may in some cases also involve fetching only segments of one or more of the SDll(s) from the memory or fetching SDU data of multiple SDlls or SDU segments in a single access operation from the memory.

[0085] At step 920, the wireless communication device sends one or more wireless transmissions conveying a sequence of concatenated PDUs to the further wireless communication device. The concatenated PDUs. The concatenated PDUs each include at least one SDU and / or at least one SDU segment of an SDU, e.g., corresponding to the SDU data obtained at step 910.

[0086] At step 930, the wireless communication device receives at least one status message from the further wireless communication device. The status message includes a first field indicating, in terms of a respective SN, one or more of the concatenated PDUs for which reception by the further wireless communication device was not successful, and / or a second field indicating, in terms of a respective SN, a last one of the concatenated PDUs for which reception by the further wireless communication device was successful. The respective SN of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment included in the concatenated PDU.

[0087] The first field and / or second field may provide feedback concerning reception of the concatenated PDUs by the further wireless communication device. If reception of a concatenated PDU was successful, the feedback may acknowledge successful reception based on the SN of the successfully received concatenated PDU. This may be accomplished based on a format which includes an acknowledgment SN to identify the SN of the at least one successfully received concatenated PDU, e.g., as explained in connection with the ACK_SN field of Fig. 7. For example, the first field could include a value of ACK_SN = SN* + 1 , where SN* denotes the highest SN of the successfully received SNs. The first field may thus correspond to the ACK_SN field in the example of Fig. 7.

[0088] In addition or as an alternative, the second field could indicate unsuccessful reception of at least one of the concatenated PDUs based on a format including a negative acknowledgment SN to identify the sequence number of the at least one unsuccessfully received concatenated PDU, e.g., as explained in connection with the NACK_SN field of Fig. 7. Further, the second field could indicate unsuccessful reception of at least one of the concatenated PDUs based on a format including a negative acknowledgment SN and a negative acknowledgment SN range to identify the SNs of the at least one unsuccessfully received concatenated PDU, e.g., as explained in connection with the NACK_SN and NACK range fields of Fig. 7. Further, the second field could indicate unsuccessful reception of an SDU segment conveyed by one of the concatenated PDlls based on a format including a negative acknowledgment SN to identify the concatenated PDU, a first SO to identify a start of the unsuccessfully received SDU segment and a second SO to identify an end of the unsuccessfully received SDU segment, e.g., as explained in connection with the NACK_SN, SOstart, and SOend fields of Fig. 7. The first SO and the second SO may be defined with respect to a reference SDU of the identified concatenated PDU. The first SO may indicate a number of bytes from the start of the reference SDU to a first SDU byte of the unsuccessfully received SDU segment and the second SO may indicate a number of bytes from the start of the reference SDU to a last SDU byte of the unsuccessfully received SDU segment. The second field may thus correspond to the NACK_SN field in the example of Fig. 7, optionally in combination with the NACK range field and / or the SOstart and SOend fields of Fig. 7.

[0089] Based on the information in the first field and / or second field, the wireless communication device may control retransmission of at least one SDU and / or at least one SDU segment of one or more SDUs conveyed by the data parts of the concatenated PDUs.

[0090] The status message may for example be included in a control PDU, e.g., using a format as illustrated in Fig. 7.

[0091] Each PDU of the concatenated PDUs may have a format including a data part and a header part. The data part may include the at least one SDU and / or the at least one SDU segment. The header part may include the SN of the concatenated PDU. Fig. 6 shows an example of a corresponding PDU format. The concatenated PDUs may correspond to RLC PDUs.

[0092] In some scenarios, at least some of the PDUs may include an SO defined with respect to a reference SDU. Typically, at least an SDU segment of the reference SDU is conveyed in the data part of the concatenated PDU. However, in some cases it could also occur that no segment of the reference SDU is conveyed in the concatenated PDU, e.g., if the concatenated PDU corresponds to a retransmission. For such retransmissions, the SN and reference SDU may be maintained from the initial transmission of the SDU data.

[0093] The reference SDU may be specified individually for each concatenated PDU. For example, if the data parts of the sequence of concatenated PDUs convey a sequence of SDUs, the reference SDU may correspond to the first SDU of the sequence of SDUs, of which at least an SDU segment is included in the data part of the concatenated PDU. In some scenarios, the SO could also be omitted. For example, for at least one of the concatenated PDlls the SO could not be included in the PDU, e.g., in response to a start of the reference SDU being included in the concatenated PDU. In some scenarios, for the at least one of the concatenated PDUs, the PDU could further include an indicator indicating that the SO is not included.

[0094] The SO may refer to a start of the reference SDU. More specifically, the SO may indicate a number of bytes from the start of the reference SDU to a first SDU byte in the concatenated PDU.

[0095] In some scenarios, the at least one of the concatenated PDUs may further include or more length indicators indicating a length of a respective SDU within the concatenated PDU, e.g., as explained for the LI fields in the data format of Fig. 6. Such length indicator(s) may be selectively included in response to the data part of the concatenated PDU conveying data of multiple SDUs. The inclusion of the length indicator(s) may be indicated by an extension indicator preceding the respective length indicator.

[0096] The assignment of the SNs to the concatenated PDUs may be such that, for each concatenated PDU, the SN is assigned based on whether the concatenated PDU includes at least an SDU segment of a new SDU of the one or more SDUs. Here, the SDU is considered a new SDU if a previous concatenated PDU of the sequence of concatenated PDUs does not include a segment of this SDU. This may involve that, in response to the concatenated PDU including at least an SDU segment of a new SDU, the SN is incremented with respect to the SN of the previous concatenated PDU of the sequence of concatenated PDUs. This incrementation may for example involve incrementing the SN by one, but other step sizes could be used as well. It is also noted that for a first concatenated PDU of the sequence, a predefined initial value of the SN may be assigned, such as zero. In response to the data part of the PDU not including at least an SDU segment of a new SDU, the SN of the concatenated PDU may in turn be maintained from the previous concatenated PDU of the sequence of concatenated PDUs.

[0097] In some scenarios, if the sequence of concatenated PDUs includes a first concatenated PDU and a subsequent second concatenated PDU, the first concatenated PDU may include at least an SDU segment of a first SDU while the second concatenated PDU includes a further SDU segment of the first SDU. Corresponding examples are described in connection with Fig. 3B, 4A, 4B, 5A, and 5B. Further, if the sequence of concatenated PDUs includes a first concatenated PDU and a subsequent second concatenated PDU, the first concatenated PDU could include at least an SDU segment of a first SDU while the second concatenated PDU includes a further SDU segment of the first SDU and at least an SDU segment of a second SDU. Corresponding examples are described in connection with Fig. 3B, 5A, and 5B.

[0098] Fig. 10 shows a flowchart for illustrating a method, which may be utilized for implementing the illustrated concepts. The method of Fig. 10 may be used for implementing the illustrated concepts in a wireless communication device which wirelessly communicates with a further wireless communication device. The wireless communication device may for example correspond to a network node, e.g., to the above-mentioned access node 100, or to a UE, e.g., to any of the above-mentioned UEs 10. If the wireless communication device is a network node, such as the above-mentioned access node 100, the further wireless communication device may correspond to a UE, such as the any of the above-mentioned UEs 10. If the wireless communication device is a UE, such as the any of the above-mentioned UEs 10, the further wireless communication device may be a network node, such as the above-mentioned access node 100, or another UE, such as any of the above-mentioned UEs 10.

[0099] If a processor-based implementation of the wireless communication device is used, at least some of the steps of the method of Fig. 10 may be performed and / or controlled by one or more processors of the wireless communication device. Such wireless communication device may also include a memory storing program code for implementing at least some of the below described functionalities or steps of the method of Fig. 10.

[0100] At step 1010, the wireless communication device receives one or more wireless transmissions conveying a sequence of concatenated PDUs from the further wireless communication device. Each PDU of the concatenated PDUs has a format including a data part and a header part. The data part is for conveying at least one SDU and / or at least one SDU segment of an SDU, e.g., corresponding to the SDU data from step 810. The data part may thus include the SDU data so that the SDU data can be conveyed by means of the wireless transmission / s) to the further wireless communication device. The header part includes an SN of the concatenated PDU. The SN is assigned based on the at least one SDU and / or at least one SDU segment included in the data part. Fig. 6 shows an example of a corresponding PDU format. The concatenated PDUs may correspond to RLC PDUs.

[0101] In some scenarios, the header part further includes an SO defined with respect to a reference SDU. Typically, at least an SDU segment of the reference SDU is conveyed in the data part of the concatenated PDU. However, in some cases it could also occur that no segment of the reference SDU is conveyed in the concatenated PDU, e.g., if the concatenated PDU corresponds to a retransmission. For such retransmissions, the SN and reference SDU may be maintained from the initial transmission of the SDU data.

[0102] The reference SDU may be specified individually for each concatenated PDU. For example, if the data parts of the sequence of concatenated PDUs convey a sequence of SDUs, the reference SDU may correspond to the first SDU of the sequence of SDUs, of which at least an SDU segment is included in the data part of the concatenated PDU.

[0103] In some scenarios, the SO could also be omitted. For example, for at least one of the concatenated PDUs the SO could not be included in the header part of the PDU, e.g., in response to a start of the reference SDU being included in the data part of the concatenated PDU. In some scenarios, for the at least one of the concatenated PDUs, the header part could further include an indicator indicating that the SO is not included in the header part.

[0104] The SO may refer to a start of the reference SDU. More specifically, the SO may indicate a number of bytes from the start of the reference SDU to a first SDU byte in the data part of the concatenated PDU.

[0105] In some scenarios, the header part may further include or more length indicators indicating a length of a respective SDU within the data part of the concatenated PDU, e.g., as explained for the LI fields in the data format of Fig. 6. Such length indicator(s) may be selectively included in response to the data part of the concatenated PDU conveying data of multiple SDUs. The inclusion of the length indicator(s) may be indicated by an extension indicator preceding the respective length indicator.

[0106] The assignment of the SNs to the concatenated PDUs may be such that, for each concatenated PDU, the SN is assigned based on whether the data part of the concatenated PDU includes at least an SDU segment of a new SDU of the one or more SDUs. Here, the SDU is considered a new SDU if the data part of a previous concatenated PDU of the sequence of concatenated PDUs does not include a segment of this SDU. This may involve that, in response to the data part of the concatenated PDU including at least an SDU segment of a new SDU, the SN is incremented with respect to the SN of the previous concatenated PDU of the sequence of concatenated PDUs. This incrementation may for example involve incrementing the SN by one, but other step sizes could be used as well. It is also noted that for a first concatenated PDU of the sequence, a predefined initial value of the SN may be assigned, such as zero. In response to the data part of the PDU not including at least an SDU segment of a new SDU, the SN of the concatenated PDU may in turn be maintained from the previous concatenated PDU of the sequence of concatenated PDUs.

[0107] In some scenarios, if the sequence of concatenated PDUs includes a first concatenated PDU and a subsequent second concatenated PDU, the data part of the first concatenated PDU may include at least an SDU segment of a first SDU while the data part of the second concatenated PDU includes a further SDU segment of the first SDU. Corresponding examples are described in connection with Fig. 3B, 4A, 4B, 5A, and 5B. Further, if the sequence of concatenated PDUs includes a first concatenated PDU and a subsequent second concatenated PDU, the data part of the first concatenated PDU could include at least an SDU segment of a first SDU while the data part of the second concatenated PDU includes a further SDU segment of the first SDU and at least an SDU segment of a second SDU. Corresponding examples are described in connection with Fig. 3B, 5A, and 5B.

[0108] At step 1020, the wireless communication device may re-assemble the SDU(s) conveyed by the concatenated PDUs. This may be accomplished based on the SNs included in the concatenated PDUs, optionally further taking into account the SO and / or other indicators that may be included in the concatenated PDUs, such as the above-mentioned length indicator(s). In some scenarios, the wireless communication device may also consider the SNs and optionally the SO and / or length indicator(s) when storing SDU data of the SDU(s) in a memory of the wireless communication device, so that storage of the SDU data in the memory may be accomplished according to the original order in the SDU(s), irrespective of any SDU or SDU segment having been received out-of-order, e.g., due to a retransmission.

[0109] At step 1030, the wireless communication device may send feedback concerning reception of the concatenated PDUs. In particular, for each of the concatenated PDUs, the wireless communication device may send feedback concerning reception of the concatenated PDU by the wireless communication device. If reception of the concatenated PDU was successful, the feedback may acknowledge successful reception based on the SN of the successfully received concatenated PDU. This may be accomplished based on a format which includes an acknowledgment SN to identify the SN of the at least one successfully received concatenated PDU, e.g., as explained in connection with the ACK_SN field of Fig. 7. For example, the feedback could include a value of ACK_SN = SN* + 1 , where SN* denotes the highest SN of the successfully received SNs. In addition or as an alternative, the feedback could indicate unsuccessful reception of at least one of the concatenated PDUs based on a format including a negative acknowledgment SN to identify the sequence number of the at least one unsuccessfully received concatenated PDU, e.g., as explained in connection with the NACK_SN field of Fig. 7. Further, the feedback could indicate unsuccessful reception of at least one of the concatenated PDlls based on a format including a negative acknowledgment SN and a negative acknowledgment SN range to identify the SNs of the at least one unsuccessfully received concatenated PDU, e.g., as explained in connection with the NACK_SN and NACK range fields of Fig. 7. Further, the feedback could indicate unsuccessful reception of an SDU segment conveyed by one of the concatenated PDlls based on a format including a negative acknowledgment SN to identify the concatenated PDU, a first SO to identify a start of the unsuccessfully received SDU segment and a second SO to identify an end of the unsuccessfully received SDU segment, e.g., as explained in connection with the NACK_SN, SOstart, and SOend fields of Fig. 7. The first SO and the second SO may be defined with respect to a reference SDU of the identified concatenated PDU, e.g., the above- mentioned reference SDU used for determination of the SO indicated in the header part of the concatenated PDU. The first SO may indicate a number of bytes from the start of the reference SDU to a first SDU byte of the unsuccessfully received SDU segment and the second SO may indicate a number of bytes from the start of the reference SDU to a last SDU byte of the unsuccessfully received SDU segment. The feedback may for example be included in a control PDU, e.g., using a format as illustrated in Fig. 7. Based on the feedback, the further wireless communication device may control retransmission of at least one SDU and / or at least one SDU segment of one or more SDUs conveyed by the data parts of the concatenated PDUs.

[0110] Fig. 11 shows a flowchart for illustrating a method, which may be utilized for implementing the illustrated concepts. The method of Fig. 11 may be used for implementing the illustrated concepts in a wireless communication device which wirelessly communicates with a further wireless communication device. The wireless communication device may for example correspond to a network node, e.g., to the above-mentioned access node 100, or to a UE, e.g., to any of the above-mentioned UEs 10. If the wireless communication device is a network node, such as the above-mentioned access node 100, the further wireless communication device may correspond to a UE, such as the any of the above-mentioned UEs 10. If the wireless communication device is a UE, such as the any of the above-mentioned UEs 10, the further wireless communication device may be a network node, such as the above-mentioned access node 100, or another UE, such as any of the above-mentioned UEs 10.

[0111] If a processor-based implementation of the wireless communication device is used, at least some of the steps of the method of Fig. 11 may be performed and / or controlled by one or more processors of the wireless communication device. Such wireless communication device may also include a memory storing program code for implementing at least some of the below described functionalities or steps of the method of Fig. 11 . At step 1110, the wireless communication device receives sends one or more wireless transmissions conveying a sequence of concatenated PDlls from the further wireless communication device. The concatenated PDlls each include at least one SDU and / or at least one SDU segment of an SDU.

[0112] Each PDU of the concatenated PDUs may have a format including a data part and a header part. The data part may include the at least one SDU and / or the at least one SDU segment. The header part may include the SN of the concatenated PDU. Fig. 6 shows an example of a corresponding PDU format. The concatenated PDUs may correspond to RLC PDUs.

[0113] In some scenarios, at least some of the PDUs may include an SO defined with respect to a reference SDU. Typically, at least an SDU segment of the reference SDU is conveyed in the data part of the concatenated PDU. However, in some cases it could also occur that no segment of the reference SDU is conveyed in the concatenated PDU, e.g., if the concatenated PDU corresponds to a retransmission. For such retransmissions, the SN and reference SDU may be maintained from the initial transmission of the SDU data.

[0114] The reference SDU may be specified individually for each concatenated PDU. For example, if the data parts of the sequence of concatenated PDUs convey a sequence of SDUs, the reference SDU may correspond to the first SDU of the sequence of SDUs, of which at least an SDU segment is included in the data part of the concatenated PDU.

[0115] In some scenarios, the SO could also be omitted. For example, for at least one of the concatenated PDUs the SO could not be included in the PDU, e.g., in response to a start of the reference SDU being included in the concatenated PDU. In some scenarios, for the at least one of the concatenated PDUs, the PDU could further include an indicator indicating that the SO is not included.

[0116] The SO may refer to a start of the reference SDU. More specifically, the SO may indicate a number of bytes from the start of the reference SDU to a first SDU byte in the concatenated PDU.

[0117] In some scenarios, the at least one of the concatenated PDUs may further include or more length indicators indicating a length of a respective SDU within the concatenated PDU, e.g., as explained for the LI fields in the data format of Fig. 6. Such length indicator(s) may be selectively included in response to the data part of the concatenated PDU conveying data of multiple SDlls. The inclusion of the length indicator(s) may be indicated by an extension indicator preceding the respective length indicator.

[0118] In some scenarios, if the sequence of concatenated PDlls includes a first concatenated PDU and a subsequent second concatenated PDU, the first concatenated PDU may include at least an SDU segment of a first SDU while the second concatenated PDU includes a further SDU segment of the first SDU. Corresponding examples are described in connection with Fig. 3B, 4A, 4B, 5A, and 5B. Further, if the sequence of concatenated PDUs includes a first concatenated PDU and a subsequent second concatenated PDU, the first concatenated PDU could include at least an SDU segment of a first SDU while the second concatenated PDU includes a further SDU segment of the first SDU and at least an SDU segment of a second SDU. Corresponding examples are described in connection with Fig. 3B, 5A, and 5B.

[0119] At step 1120, the wireless communication device may re-assemble the SDU(s) included in the concatenated PDUs. This may be accomplished based on the SNs included in the concatenated PDUs, optionally further taking into account the SO and / or other indicators that may be included in the concatenated PDUs, such as the above-mentioned length indicator(s). In some scenarios, the wireless communication device may also consider the SNs and optionally the SO and / or length indicator(s) when storing SDU data of the SDU(s) in a memory of the wireless communication device, so that storage of the SDU data in the memory may be accomplished according to the original order in the SDU(s), irrespective of any SDU or SDU segment having been received out-of-order, e.g., due to a retransmission.

[0120] At step 1130, the wireless communication device sends at least one status message to the further wireless communication device. The status message includes a first field indicating, in terms of a respective SN, one or more of the concatenated PDUs for which reception by the further wireless communication device was not successful, and / or a second field indicating, in terms of a respective SN, a last one of the concatenated PDUs for which reception by the further wireless communication device was successful. The respective SN of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment included in the concatenated PDU.

[0121] The assignment of the SNs to the concatenated PDUs may be such that, for each concatenated PDU, the SN is assigned based on whether the concatenated PDU includes at least an SDU segment of a new SDU of the one or more SDUs. Here, the SDU is considered a new SDU if a previous concatenated PDU of the sequence of concatenated PDUs does not include a segment of this SDU. This may involve that, in response to the concatenated PDU including at least an SDU segment of a new SDU, the SN is incremented with respect to the SN of the previous concatenated PDU of the sequence of concatenated PDlls. This incrementation may for example involve incrementing the SN by one, but other step sizes could be used as well. It is also noted that for a first concatenated PDU of the sequence, a predefined initial value of the SN may be assigned, such as zero. In response to the data part of the PDU not including at least an SDU segment of a new SDU, the SN of the concatenated PDU may in turn be maintained from the previous concatenated PDU of the sequence of concatenated PDUs.

[0122] The first field and / or second field may provide feedback concerning reception of the concatenated PDUs by the further wireless communication device. If reception of a concatenated PDU was successful, the feedback may acknowledge successful reception based on the SN of the successfully received concatenated PDU. This may be accomplished based on a format which includes an acknowledgment SN to identify the SN of the at least one successfully received concatenated PDU, e.g., as explained in connection with the ACK_SN field of Fig. 7. For example, the first field could include a value of ACK_SN = SN* + 1 , where SN* denotes the highest SN of the successfully received SNs. The first field may thus correspond to the ACK_SN field in the example of Fig. 7.

[0123] In addition or as an alternative, the second field could indicate unsuccessful reception of at least one of the concatenated PDUs based on a format including a negative acknowledgment SN to identify the sequence number of the at least one unsuccessfully received concatenated PDU, e.g., as explained in connection with the NACK_SN field of Fig. 7. Further, the second field could indicate unsuccessful reception of at least one of the concatenated PDUs based on a format including a negative acknowledgment SN and a negative acknowledgment SN range to identify the SNs of the at least one unsuccessfully received concatenated PDU, e.g., as explained in connection with the NACK_SN and NACK range fields of Fig. 7. Further, the second field could indicate unsuccessful reception of an SDU segment conveyed by one of the concatenated PDUs based on a format including a negative acknowledgment SN to identify the concatenated PDU, a first SO to identify a start of the unsuccessfully received SDU segment and a second SO to identify an end of the unsuccessfully received SDU segment, e.g., as explained in connection with the NACK_SN, SOstart, and SOend fields of Fig. 7. The first SO and the second SO may be defined with respect to a reference SDU of the identified concatenated PDU. The first SO may indicate a number of bytes from the start of the reference SDU to a first SDU byte of the unsuccessfully received SDU segment and the second SO may indicate a number of bytes from the start of the reference SDU to a last SDU byte of the unsuccessfully received SDU segment. The second field may thus correspond to the NACK_SN field in the example of Fig. 7, optionally in combination with the NACK range field and / or the SOstart and SOend fields of Fig. 7.

[0124] Based on the information in the first field and / or second field, the further wireless communication device may control retransmission of at least one SDU and / or at least one SDU segment of one or more SDlls conveyed by the data parts of the concatenated PDlls.

[0125] The status message may for example be included in a control PDU, e.g., using a format as illustrated in Fig. 7.

[0126] It is noted that at least some the methods of Figs. 8, 9, 10, and 11 could also be combined, e.g., in a system including at least one wireless communication device operating as a transmitting wireless communication device according to the method of Fig. 8 and at least one further wireless communication device operating as a receiving wireless communication device according to the method of Fig. 10, or in a system including at least one wireless communication device operating as a transmitting wireless communication device according to the method of Fig. 9 and at least one further wireless communication device operating as a receiving wireless communication device according to the method of Fig. 11.

[0127] Fig. 12 illustrates a processor-based implementation of a wireless device 1200 for operation in a wireless communication network, which may be used for implementing the abovedescribed concepts. More specifically, the structures of the wireless device 1200 may be used to implement the above-described functionalities in a UE, such as any of the above-mentioned UEs 10.

[0128] As illustrated, the wireless device 1200 may include wireless interface 1210, which may be used for wireless communication with one or more nodes of the wireless communication network.

[0129] Further, the wireless device 1200 may include one or more processors 950 coupled to the interface 1210 and a memory 1260 coupled to the processor(s) 1250. By way of example, the interface 1210, the processor(s) 1250, and the memory 260 could be coupled by one or more internal bus systems of the wireless device 1200. The memory 1260 may include a read-only memory (ROM), e.g., a flash ROM, a random-access memory (RAM), e.g., a dynamic RAM (DRAM) or static RAM (SRAM), a mass storage, e.g., a hard disk or solid state disk, or the like. As illustrated, the memory 1260 may include software 1270 and / or firmware 1280. The memory 1260 may include suitably configured program code to be executed by the processor(s) 1250 so as to implement or configure the above-described functionalities for wireless communication, such as explained in connection with Fig. 8, 9, 10, or 11.

[0130] It is to be understood that the structures as illustrated in Fig. 12 are merely schematic and that the wireless device 1200 may actually include further components which, for the sake of clarity, have not been illustrated, e.g., further interfaces or further processors. Also, it is to be understood that the memory 1260 may include further program code for implementing known functionalities of a UE in a 3GPP system. According to some embodiments, also a computer program may be provided for implementing functionalities of the wireless device 1200, e.g., in the form of a physical medium storing the program code and / or other data to be stored in the memory 1260 or by making the program code available for download or by streaming.

[0131] Fig. 13 illustrates a processor-based implementation of a network node 1300 for operation in a wireless communication network, which may be used for implementing the above-described concepts. More specifically, the structures of the network node 1300 may be used to implement the above-described functionalities in a radio access node, such as the above-mentioned access node 100.

[0132] As illustrated, the network node 1300 may include wireless interface 1310, which may be used for wireless communication with one or more wireless devices, such as the above-mentioned UEs 10. Further, the network node 1300 may include a network interface 1320, which may be used for communication with other network nodes.

[0133] Further, the network node 1300 may include one or more processors 1350 coupled to the interfaces 1310, 1320 and a memory 1360 coupled to the processor(s) 1350. By way of example, the interfaces 1310, 1320, the processor(s) 1350, and the memory 1360 could be coupled by one or more internal bus systems of the network node 1300. The memory 1360 may include a ROM, e.g., a flash ROM, a RAM, e.g., a DRAM or SRAM, a mass storage, e.g., a hard disk or solid state disk, or the like. As illustrated, the memory 1360 may include software 1370 and / or firmware 1380. The memory 1360 may include suitably configured program code to be executed by the processor(s) 1350 so as to implement or configure the above-described functionalities for wireless communication, such as explained in connection with Fig. 8, 9, 10, or 11.

[0134] It is to be understood that the structures as illustrated in Fig. 13 are merely schematic and that the network node 1300 may actually include further components which, for the sake of clarity, have not been illustrated, e.g., further interfaces or further processors. Also, it is to be understood that the memory 1360 may include further program code for implementing known functionalities of a radio access node in a 3GPP system. According to some embodiments, also a computer program may be provided for implementing functionalities of the network node 1300, e.g., in the form of a physical medium storing the program code and / or other data to be stored in the memory 1360 or by making the program code available for download or by streaming.

[0135] Fig. 14 shows a communication diagram of a host 1402 communicating via a network node 1404 with a UE 1406 over a partially wireless connection in accordance with some embodiments. Example implementations, in accordance with various embodiments, of the UE (such as one of the above-mentioned UEs 10), network node (such as the above-mentioned access node 100), and host (such as the above-mentioned service platform 250 or application server(s) 300) will now be described with reference to Fig. 14.

[0136] Embodiments of host 1402 include hardware, such as a communication interface, processing circuitry, and memory. The host 1402 also includes software, which is stored in or accessible by the host 1402 and executable by the processing circuitry. The software includes a host application that may be operable to provide a service to a remote user, such as the UE 1406 connecting via an over-the-top (OTT) connection 1450 extending between the UE 1406 and host 1402. In providing the service to the remote user, a host application may provide user data which is transmitted using the OTT connection 1450.

[0137] The network node 1404 includes hardware enabling it to communicate with the host 1402 and UE 1406. The connection 1460 may be direct or pass through a core network (like core network 210 of Fig. 1) and / or one or more other intermediate networks, such as one or more public, private, or hosted networks. For example, an intermediate network may be a backbone network or the Internet.

[0138] The UE 1406 includes hardware and software, which is stored in or accessible by UE 1406 and executable by the UE’s processing circuitry. The software includes a client application, such as a web browser or operator-specific “app” that may be operable to provide a service to a human or non-human user via UE 1406 with the support of the host 1402. In the host 1402, an executing host application may communicate with the executing client application via the OTT connection 1450 terminating at the UE 1406 and host 1402. In providing the service to the user, the UE's client application may receive request data from the host's host application and provide user data in response to the request data. The OTT connection 1450 may transfer both the request data and the user data. The UE's client application may interact with the user to generate the user data that it provides to the host application through the OTT connection 1450.

[0139] The OTT connection 1450 may extend via a connection 1460 between the host 1402 and the network node 1404 and via a wireless connection 1470 between the network node 1404 and the UE 1406 to provide the connection between the host 1402 and the UE 1406. The connection 1460 and wireless connection 1470, over which the OTT connection 1450 may be provided, have been drawn abstractly to illustrate the communication between the host 1402 and the UE 1406 via the network node 1404, without explicit reference to any intermediary devices and the precise routing of messages via these devices.

[0140] As an example of transmitting data via the OTT connection 1450, in step 1408, the host 1402 provides user data, which may be performed by executing a host application. In some embodiments, the user data is associated with a particular human user interacting with the UE 1406. In other embodiments, the user data is associated with a UE 1406 that shares data with the host 1402 without explicit human interaction. In step 1410, the host 1402 initiates a transmission carrying the user data towards the UE 1406. The host 1402 may initiate the transmission responsive to a request transmitted by the UE 1406. The request may be caused by human interaction with the UE 1406 or by operation of the client application executing on the UE 1406. The transmission may pass via the network node 1404, in accordance with the teachings of the embodiments described throughout this disclosure. Accordingly, in step 1412, the network node 1404 transmits to the UE 1406 the user data that was carried in the transmission that the host 1402 initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In step 1414, the UE 1406 receives the user data carried in the transmission, which may be performed by a client application executed on the UE 1406 associated with the host application executed by the host 1402.

[0141] In some examples, the UE 1406 executes a client application which provides user data to the host 1402. The user data may be provided in reaction or response to the data received from the host 1402. Accordingly, in step 1416, the UE 1406 may provide user data, which may be performed by executing the client application. In providing the user data, the client application may further consider user input received from the user via an input / output interface of the UE 1406. Regardless of the specific manner in which the user data was provided, the UE 1406 initiates, in step 1418, transmission of the user data towards the host 1402 via the network node 1404. In step 1420, in accordance with the teachings of the embodiments described throughout this disclosure, the network node 1404 receives user data from the UE 1406 and initiates transmission of the received user data towards the host 1402. In step 1422, the host 1402 receives the user data carried in the transmission initiated by the UE 1406.

[0142] The illustrated concepts may help to improve performance of OTT services provided to the UE 1406 using the OTT connection 1450, in which the wireless connection 1470 forms a segment. More precisely, the teachings of the illustrated concepts may allow for improving performance of the wireless connection 1470, and thus also of the OTT connection, by enabling efficient utilization of PDU concatenation, with the possibility of SDU segmentation. As a result user experience for the OTT services can be improved.

[0143] In an example scenario, factory status information may be collected and analyzed by the host 1402. As another example, the host 1402 may process audio and video data which may have been retrieved from a UE for use in creating maps. As another example, the host 1402 may collect and analyze real-time data to assist in controlling vehicle congestion (e.g., controlling traffic lights). As another example, the host 1402 may store surveillance video uploaded by a UE. As another example, the host 1402 may store or control access to media content such as video, audio, VR or AR which it can broadcast, multicast or unicast to UEs. As other examples, the host 1402 may be used for energy pricing, remote control of non-time critical electrical load to balance power generation needs, location services, presentation services (such as compiling diagrams etc. from data collected from remote devices), or any other function of collecting, retrieving, storing, analyzing and / or transmitting data.

[0144] In some examples, a measurement procedure may be provided for the purpose of monitoring data rate, latency, and other factors on which the one or more embodiments improve. There may further be an optional network functionality for reconfiguring the OTT connection 1450 between the host 1402 and UE 1406, in response to variations in the measurement results. The measurement procedure and / or the network functionality for reconfiguring the OTT connection may be implemented in software and hardware of the host 1402 and / or UE 1406. In some embodiments, sensors (not shown) may be deployed in or in association with other devices through which the OTT connection 1450 passes; the sensors may participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 1450 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not directly alter the operation of the network node 1404. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling that facilitates measurements of throughput, propagation times, latency and the like, by the host 1402. The measurements may be implemented in that software causes messages to be transmitted, in particular empty or ‘dummy’ messages, using the OTT connection 1450 while monitoring propagation times, errors, etc.

[0145] As can be seen, the concepts as described above may be used for improved wireless communication, by enabling efficient usage of PDU concatenation, with the possibility of SDU segmentation. In this way, memory accesses related to storage of SDU data can be managed more efficiently, and a number of required memory accesses at the transmitting wireless communication device be reduced. At the receiving wireless communication device, reassembly of SDUs can be performed in an efficient manner and excessive memory fragmentation be avoided. Further, excessive complexity can be avoided by enabling PDU concatenation and SDU segmentation based on a single data PDU format.

[0146] It is to be understood that the examples and embodiments as explained above are merely illustrative and susceptible to various modifications. For example, the illustrated concepts may be applied to various types of wireless transmissions, also including scenarios where the wireless transmissions are received by multiple receivers, such as for broadcast or groupcast transmissions. Further, the illustrated concepts may be applied in connection with various kinds of wireless communication technologies, also including modifications or enhancements of the 4G LTE technology or of the 5G NR technology. Moreover, it is to be understood that the above concepts may be implemented by using correspondingly designed software to be executed by one or more processors of an existing device or apparatus, or by using dedicated device hardware. Further, it should be noted that the illustrated apparatuses or devices may each be implemented as a single device or as a system of multiple interacting devices or modules.

Claims

Claims1. A method for communicating in a wireless communication network, the method comprising: a wireless communication device (10, 100; 1200; 1300; 1404, 1406) sending one or more wireless transmissions conveying a sequence of concatenated Packet Data Units, PDUs, to a further wireless communication device (10, 100; 1200; 1300; 1404, 1406), wherein each PDU of the concatenated PDUs has a format comprising:- a data part for conveying at least one Service Data Unit, SDU, and / or at least one SDU segment of an SDU; and- a header part comprising a sequence number of the concatenated PDU, and wherein the sequence number is assigned based on the at least one SDU and / or at least one SDU segment included in the data part.

2. The method according to claim 1 , wherein for each concatenated PDU the sequence number is assigned based on whether the data part of the concatenated PDU comprises at least an SDU segment of a new SDU of the one or more SDUs, wherein the data part of a previous concatenated PDU of the sequence of concatenated PDUs does not comprise a segment of the new SDU.

3. The method according to claim 2, wherein, in response to the data part of the concatenated PDU comprising at least an SDU segment of a new SDU, the sequence number is incremented with respect to the sequence number of the previous concatenated PDU of the sequence of concatenated PDUs.

5. The method according to claim 2, wherein, in response to the data part of the PDU not comprising at least an SDU segment of a new SDU, the sequence number of the concatenated PDU is maintained from the previous concatenated PDU of the sequence of concatenated PDUs.

6. The method according to any of the preceding claims, wherein the sequence of concatenated PDUs comprises a first concatenated PDU and a subsequent second concatenated PDU, wherein the data part of the first concatenated PDU comprises at least an SDU segment of a first SDU and the data part of the second concatenated PDU comprises a further SDU segment of the first SDU.

7. The method according to any of the preceding claims,wherein the sequence of concatenated PDlls comprises a first concatenated PDU and a subsequent second concatenated PDU, wherein the data part of the first concatenated PDU comprises at least an SDU segment of a first SDU and the data part of the second concatenated PDU comprises a further SDU segment of the first SDU and at least an SDU segment of a second SDU.

8. The method according to any of the preceding claims, wherein the header part further comprises a segmentation offset defined with respect to a reference SDU, of which at least an SDU segment is conveyed in the data part of the concatenated PDU.

9. The method according to claim 8, wherein the reference SDU is specified individually for each concatenated PDU.

10. The method according to claim 9, wherein the data parts of the sequence of concatenated PDUs convey a sequence of SDUs, and wherein the reference SDU corresponds to the first SDU of the sequence of SDUs, of which at least an SDU segment is comprised in the data part of the concatenated PDU.11 . The method according to any of claims 8 to 10, wherein for at least one of the concatenated PDUs the segmentation offset is not included in the header part.

12. The method according to claim 11 , wherein the segmentation offset is not included in response to a start of the reference SDU being included in the data part of the concatenated PDU.

13. The method according to claim 11 or 12, wherein, for the at least one of the concatenated PDUs, the header part further comprises an indicator indicating that the segmentation offset is not included in the header part.

14. The method according to any of claims 8 to 13, wherein the segmentation offset refers to a start of the reference SDU.

15. The method according to claim 14,wherein the segmentation offset indicates a number of bytes from the start of the reference SDU to a first SDU byte in the data part of the concatenated PDU.

16. The method according to any of the preceding claims, wherein the header part further comprises one or more length indicators indicating a length of a respective SDU within the data part of the concatenated PDU.

17. The method according to claim 16, wherein the one or more length indicators are selectively included in response to the data part of the concatenated PDU conveying data of multiple SDUs.

18. The method according to claim 17, wherein inclusion of the one or more length indicators is indicated by an extension indicator preceding the respective length indicator.

19. The method according to any of the preceding claims, wherein for each of the concatenated PDUs, the wireless communication device (10, 100; 1200; 1300; 1404, 1406) expects feedback concerning reception of the concatenated PDU by the further wireless communication device (10, 100; 1200; 1300; 1404, 1406).

20. The method according to claim 19, wherein, if reception of the concatenated PDU was successful, the feedback acknowledges successful reception based on the sequence number of the successfully received concatenated PDU.

21. The method according to claim 19 or 20, wherein the feedback acknowledges successful reception of at least one of the concatenated PDUs based on a format comprising an acknowledgment sequence number to identify the sequence number of the at least one successfully received concatenated PDU.

22. The method according to any of claims 19 to 21 , wherein the feedback indicates unsuccessful reception of at least one of the concatenated PDUs based on a format comprising a negative acknowledgment sequence number to identify the sequence number of the at least one unsuccessfully received concatenated PDU.

23. The method according to claim 22,wherein the feedback indicates unsuccessful reception of at least one of the concatenated PDlls based on a format comprising a negative acknowledgment sequence number and a negative acknowledgment sequence number range to identify the sequence number of the at least one unsuccessfully received concatenated PDU.

24. The method according to claim 22 or 23, wherein the feedback indicates unsuccessful reception of an SDU segment conveyed by one of the concatenated PDlls based on a format comprising a negative acknowledgment sequence number to identify the concatenated PDU, a first segmentation offset to identify a start of the unsuccessfully received SDU segment and a second segmentation offset to identify an end of the unsuccessfully received SDU segment.

25. The method according to claim 24, wherein the first segmentation offset and the second segmentation offset are defined with respect to a reference SDU of the identified concatenated PDU.

26. The method according to any of claims 19 to 25, wherein the feedback is comprised in a control PDU.

27. The method according to any of claims 19 to 26, comprising: based on the feedback, the wireless communication device (10, 100; 1200; 1300; 1404, 1406) controlling retransmission of at least one SDU and / or at least one SDU segment of one or more SDUs conveyed by the data parts of the concatenated PDUs.

28. The method according to any of the preceding claims, wherein the concatenated PDUs are PDUs of a Radio Link Control Protocol.

29. A method for communicating in a wireless communication network, the method comprising: a wireless communication device (10, 100; 1200; 1300; 1404, 1406) sending one or more wireless transmissions conveying a sequence of concatenated Packet Data Units, PDUs, to a further wireless communication device (10, 100; 1200; 1300; 1404, 1406), wherein each PDU of the concatenated PDUs comprises at least one Service Data Unit, SDU, and / or at least one SDU segment of an SDU; and the wireless communication device (10, 100; 1200; 1300; 1404, 1406) receiving a status message from the further wireless communication device, the status message comprising a first field indicating, in terms of a respective sequence number, one or more of the concatenated PDUs for which reception by the further wireless communication device (10,100; 1200; 1300; 1404, 1406) was not successful, and / or a second field indicating, in terms of a respective sequence number, a last one of the concatenated PDlls for which reception by the further wireless communication device (10, 100; 1200; 1300; 1404, 1406) was successful, wherein the respective sequence number of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment comprised in the concatenated PDU.

30. The method according to claim 29, wherein the respective sequence number of the concatenated PDU is assigned based on whether the concatenated PDU comprises at least an SDU segment of a new SDU of the one or more SDUs, wherein a previous concatenated PDU of the sequence of concatenated PDUs does not comprise a segment of the new SDU.31 . A method for communicating in a wireless communication network, the method comprising: a wireless communication device (10, 100; 1200; 1300; 1404, 1406) receiving one or more wireless transmissions conveying a sequence of concatenated Packet Data Units, PDUs, from a further wireless communication device (10, 100; 1200; 1300; 1404, 1406), wherein each PDU of the concatenated PDUs has a format comprising:- a data part for conveying at least one Service Data Unit, SDU, and / or at least one SDU segment of an SDU; and- a header part comprising a sequence number of the concatenated PDU, and wherein the sequence number is assigned based on the at least one SDU and / or at least one SDU segment included in the data part.

32. The method according to claim 31 , wherein for each concatenated PDU the sequence number is assigned based on whether the data part of the concatenated PDU comprises at least an SDU segment of a new SDU of the one or more SDUs, wherein the data part of a previous concatenated PDU of the sequence of concatenated does not comprise a segment of the new SDU.

33. The method according to claim 32, wherein, in response to the data part of the PDU comprising at least an SDU segment of a new SDU, the sequence number is incremented with respect to the sequence number of the previous concatenated PDU of the sequence of concatenated PDUs.

34. The method according to claim 32,wherein, in response to the data part of the PDU not comprising at least an SDU segment of a new SDU, the sequence number of the concatenated PDU is maintained from the previous concatenated PDU of the sequence of concatenated PDUs.

35. The method according to any of claims 31 to 34, wherein the sequence of concatenated PDUs comprises a first concatenated PDU and a subsequent second concatenated PDU, wherein the data part of the first concatenated PDU comprises at least an SDU segment of a first SDU and the data part of the second concatenated PDU comprises a further SDU segment of the first SDU.

36. The method according to any of claims 31 to 35, wherein the sequence of concatenated PDUs comprises a first concatenated PDU and a subsequent second concatenated PDU, wherein the data part of the first concatenated PDU comprises at least an SDU segment of a first SDU and the data part of the second concatenated PDU comprises a further SDU segment of the first SDU and at least an SDU segment of a second SDU.

37. The method according to any of claims 31 to 36, wherein the header part further comprises a segmentation offset defined with respect to a reference SDU, of which at least an SDU segment is conveyed in the data part of the concatenated PDU.

38. The method according to claim 37, wherein the data parts of the sequence of concatenated PDUs convey a sequence of SDUs, and wherein the reference SDU corresponds to the first SDU of the sequence of SDUs, of which at least an SDU segment is comprised in the data part of the concatenated PDU.

39. The method according to claim 37 or 38, wherein for at least one of the concatenated PDUs, the segmentation offset is not included in the header part.

40. The method according to claim 39, wherein the segmentation offset is not included in response to a start of the reference SDU being included in the data part of the concatenated PDU.

41. The method according to claim 39 or 40, wherein, for the at least one of the concatenated PDlls, the header part further comprises an indicator indicating that the segmentation offset is not included in the header part.

42. The method according to any of claims 37 to 41 , wherein the segmentation offset refers to a start of the reference SDU.

43. The method according to claim 42, wherein the segmentation offset indicates a number of bytes from the start of the reference SDU to a first SDU byte in the data part of the concatenated PDU.

44. The method according to any of claims 31 to 43, wherein the header part further comprises one or more length indicators indicating a length of a respective SDU within the data part of the concatenated SDU.

45. The method according to claim 44, wherein the one or more length indicators are selectively included in response to the data part of the concatenated PDU conveying data of multiple SDUs.

46. The method according to claim 45, wherein inclusion of the one or more length indicators is indicated by an extension indicator preceding the respective length indicator.

47. The method according to any of claims 31 to 46, wherein for each of the concatenated PDUs, the wireless communication device (10, 100; 1200; 1300; 1404, 1406) sends feedback concerning reception of the concatenated PDU by the wireless communication device (10, 100; 1200; 1300; 1404, 1406).

48. The method according to claim 47, wherein, if reception of the concatenated PDU was successful, the feedback acknowledges successful reception based on the sequence number of the successfully received concatenated PDU.

49. The method according to claim 47 or 48, wherein the feedback acknowledges successful reception of at least one of the concatenated PDUs based on a format comprising an acknowledgment sequence number to identify the sequence number of the at least one successfully received concatenated PDU.

50. The method according to any of claims 47 to 49, wherein the feedback indicates unsuccessful reception of at least one of the concatenated PDlls based on a format comprising a negative acknowledgment sequence number to identify the sequence number of the at least one unsuccessfully received concatenated PDU.

51. The method according to claim 50, wherein the feedback indicates unsuccessful reception of at least one of the concatenated PDlls based on a format comprising a negative acknowledgment sequence number and a negative acknowledgment sequence number range to identify the sequence number of the at least one unsuccessfully received concatenated PDU.

52. The method according to claim 50 or 51 , wherein the feedback indicates unsuccessful reception of an SDU segment conveyed by one of the concatenated PDUs based on a format comprising a negative acknowledgment sequence number to identify the concatenated PDU, a first segmentation offset to identify a start of the unsuccessfully received SDU segment and a second segmentation offset to identify an end of the unsuccessfully received SDU segment.

53. The method according to claim 52, wherein the first segmentation offset and the second segmentation offset are defined with respect to a reference SDU of the identified concatenated PDU.

54. The method according to claim 53, wherein the first segmentation offset indicates a number of bytes from the start of the reference SDU to a first SDU byte of the unsuccessfully received SDU segment and the second segmentation offset indicates a number of bytes from the start of the reference SDU to a last SDU byte of the unsuccessfully received SDU segment.

55. The method according to any of claims 47 to 54, wherein the feedback is comprised in a control PDU.

56. The method according to any of claims 31 to 55, wherein the concatenated PDUs are PDUs of a Radio Link Control Protocol.

57. A method for communicating in a wireless communication network, the method comprising:a wireless communication device (10, 100; 1200; 1300; 1404, 1406) receiving one or more wireless transmissions conveying a sequence of concatenated Packet Data Units, PDUs, from a further wireless communication device (10, 100; 1200; 1300; 1404, 1406), wherein each PDU of the concatenated PDUs comprises at least one Service Data Unit, SDU, and / or at least one SDU segment of an SDU; and the wireless communication device (10, 100; 1200; 1300; 1404, 1406) sending a status message to the further wireless communication device, the status message comprising a first field indicating, in terms of a respective sequence number, one or more of the concatenated PDUs for which reception by the wireless communication device was not successful, and / or a second field indicating, in terms of a respective sequence number, a last one of the concatenated PDUs for which reception by the wireless communication device (10, 100; 1200; 1300; 1404, 1406) was successful, wherein the respective sequence number of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment comprised in the concatenated PDU.

58. The method according to claim 57, wherein the respective sequence number of the concatenated PDU is assigned based on whether the concatenated PDU comprises at least an SDU segment of a new SDU of the one or more SDUs, wherein a previous concatenated PDU of the sequence of concatenated PDUs does not comprise a segment of the new SDU.

59. A wireless communication device (10, 100; 1200; 1300; 1404, 1406) for operation in a wireless communication network, the wireless communication device (10, 100; 1200; 1300; 1404, 1406) being configured to: send one or more wireless transmissions conveying a sequence of concatenated Packet Data Units, PDUs, to a further wireless communication device (10, 100; 1200; 1300; 1404, 1406), wherein each PDU of the concatenated PDUs has a format comprising:- a data part for conveying at least one Service Data Unit, SDU, and / or at least one SDU segment of an SDU; and- a header part comprising a sequence number of the concatenated PDU, and wherein the sequence number is assigned based on the at least one SDU and / or at least one SDU segment included in the data part.

60. The wireless communication device (10, 100; 1200; 1300; 1404, 1406) according to claim 59, wherein the wireless communication device (10, 100; 1200; 1300; 1404, 1406) is configured to perform a method according to any one of claims 2 to 28.

61. The wireless communication device (10, 100; 1200; 1300; 1404, 1406) according to claim 59 or 60, comprising: at least one processor (1250; 1350), and a memory (1260; 1360) containing program code executable by the at least one processor (1250; 1350), whereby execution of the program code by the at least one processor (1250; 1350) causes the wireless communication device (10, 100; 1200; 1300; 1404, 1406) to perform a method according to any one of claims 1 to 28.

62. A wireless communication device (10, 100; 1200; 1300; 1404, 1406) for operation in a wireless communication network, the wireless communication device (10, 100; 1200; 1300; 1404, 1406) being configured to: send one or more wireless transmissions conveying a sequence of concatenated Packet Data Units, PDUs, to a further wireless communication device (10, 100; 1200; 1300; 1404, 1406), wherein each PDU of the concatenated PDUs comprises at least one Service Data Unit, SDU, and / or at least one SDU segment of an SDU; and receive a status message from the further wireless communication device (10, 100; 1200; 1300; 1404, 1406), the status message comprising a first field indicating, in terms of a respective sequence number, one or more of the concatenated PDUs for which reception by the further wireless communication device (10, 100; 1200; 1300; 1404, 1406) was not successful, and / or a second field indicating, in terms of a respective sequence number, a last one of the concatenated PDUs for which reception by the further wireless communication device (10, 100; 1200; 1300; 1404, 1406) was successful, wherein the respective sequence number of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment comprised by the concatenated PDU.

63. The wireless communication device (10, 100; 1200; 1300; 1404, 1406) according to claim 62, wherein the respective sequence number of the concatenated PDU is assigned based on whether the concatenated PDU comprises at least an SDU segment of a new SDU of the one or more SDUs, wherein a previous concatenated PDU of the sequence of concatenated PDUs does not comprise a segment of the new SDU.

64. The wireless communication device (10, 100; 1200; 1300; 1404, 1406) according to claim62 or 63, comprising: at least one processor (1250; 1350), anda memory (1260; 1360) containing program code executable by the at least one processor (1250; 1350), whereby execution of the program code by the at least one processor (1250; 1350) causes the wireless communication device (10, 100; 1200; 1300; 1404, 1406) to perform a method according to claim 29 or 30.

65. A wireless communication device (10, 100; 1200; 1300; 1404, 1406) for operation in a wireless communication network, the wireless communication device (10, 100; 1200; 1300; 1404, 1406) being configured to: receive one or more wireless transmissions conveying a sequence of concatenated Packet Data Units, PDUs, from a further wireless communication device (10, 100; 1200; 1300; 1404, 1406), wherein each PDU of the concatenated PDUs has a format comprising:- a data part for conveying at least one Service Data Unit, SDU, and / or at least one SDU segment of an SDU; and- a header part comprising a sequence number of the concatenated PDU, and wherein the sequence number is assigned based on the at least one SDU and / or at least one SDU segment included in the data part.

66. The wireless communication device (10, 100; 1200; 1300; 1404, 1406) according to claim 65, wherein the wireless communication device (10, 100; 1200; 1300; 1404, 1406) is configured to perform a method according to any one of claims 32 to 56.

67. The wireless communication device (10, 100; 1200; 1300; 1404, 1406) according to claim 65 or 66, comprising: at least one processor (1250; 1350), and a memory (1260; 1360) containing program code executable by the at least one processor (1250; 1350), whereby execution of the program code by the at least one processor (1250; 1350) causes the wireless communication device to perform a method according to any one of claims 31 to 56.

68. A wireless communication device (10, 100; 1200; 1300; 1404, 1406) for operation in a wireless communication network, the wireless communication device (10, 100; 1200; 1300; 1404, 1406) being configured to: receive one or more wireless transmissions conveying a sequence of concatenated Packet Data Units, PDUs, from a further wireless communication device (10, 100; 1200; 1300; 1404,1406), wherein each PDU of the concatenated PDlls comprises at least one Service Data Unit, SDU, and / or at least one SDU segment of an SDU; and send a status message to the further wireless communication device (10, 100; 1200; 1300; 1404, 1406), the status message comprising a first field indicating, in terms of a respective sequence number, one or more of the concatenated PDUs for which reception by the wireless communication device (10, 100; 1200; 1300; 1404, 1406) was not successful, and / or a second field indicating, in terms of a respective sequence number, a last one of the concatenated PDUs for which reception by the wireless communication device (10, 100; 1200; 1300; 1404, 1406) was successful, wherein the respective sequence number of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment comprised in the concatenated PDU.

69. The wireless communication device (10, 100; 1200; 1300; 1404, 1406) according to claim 68, wherein the respective sequence number of the concatenated PDU is assigned based on whether the concatenated PDU comprises at least an SDU segment of a new SDU of the one or more SDUs, wherein a previous concatenated PDU of the sequence of concatenated PDUs does not comprise a segment of the new SDU.

70. The wireless communication device (10, 100; 1200; 1300; 1404, 1406) according to claim 68 or 69, comprising: at least one processor (1250; 1350), and a memory (1260; 1360) containing program code executable by the at least one processor (1250; 1350), whereby execution of the program code by the at least one processor (1250; 1350) causes the wireless communication device (10, 100; 1200; 1300; 1404, 1406) to perform a method according to claim 57 or 58.

71. A system, comprising: a first wireless communication device (10, 100; 1200; 1300; 1404, 1406) and a second wireless communication device (10, 100; 1200; 1300; 1404, 1406), wherein the first wireless communication device (10, 100; 1200; 1300; 1404, 1406) is configured to: send wireless transmissions conveying a sequence of concatenated Packet Data Units, PDUs, wherein each PDU of the concatenated PDUs has a format comprising:- a data part for conveying at least one Service Data Unit, SDU, and / or at least one SDU segment of an SDU; and- a header part comprising a sequence number of the concatenated PDU, and wherein the sequence number is assigned based on the at least one SDU and / or at least one SDU segment included in the data part; and wherein the second wireless communication device (10, 100; 1200; 1300; 1404, 1406) is configured to receive the wireless transmissions from the first wireless communication device (10, 100; 1200; 1300; 1404, 1406).

72. The system according to claim 71 , wherein the first wireless communication (10, 100; 1200; 1300; 1404, 1406) is configured to operate according to a method of any of claims 1 to 28 and / or the second wireless communication device (10, 100; 1200; 1300; 1404, 1406) is configured to operate according to a method of any of claims 31 to 56.

73. A system, comprising: a first wireless communication device (10, 100; 1200; 1300; 1404, 1406) and a second wireless communication device (10, 100; 1200; 1300; 1404, 1406), wherein the first wireless communication device (10, 100; 1200; 1300; 1404, 1406) is configured to: send one or more wireless transmissions conveying a sequence of concatenated Packet Data Units, PDUs, wherein each PDU of the concatenated PDUs comprises at least one Service Data Unit, SDU, and / or at least one SDU segment of an SDU, wherein the second wireless communication device (10, 100; 1200; 1300; 1404, 1406) is configured to send a status message to the first wireless communication device (10, 100; 1200; 1300; 1404, 1406), the status message comprising a first field indicating, in terms of a respective sequence number, one or more of the concatenated PDUs for which reception by the second wireless communication device (10, 100; 1200; 1300; 1404, 1406) was not successful, and / or a second field indicating, in terms of a respective sequence number, a last one of the concatenated PDUs for which reception by the second wireless communication device (10, 100; 1200; 1300; 1404, 1406) was successful, wherein the respective sequence number of the concatenated PDU is assigned based on the at least one SDU and / or at least one SDU segment comprised in the concatenated PDU.

74. The system according to claim 73, wherein the respective sequence number of the concatenated PDU is assigned based on whether the concatenated PDU comprises at least an SDU segment of a new SDU of the one or more SDUs, wherein a previous concatenated PDU of the sequence of concatenated PDUs does not comprise a segment of the new SDU.

75. A computer program or computer program product comprising program code to be executed by at least one processor (1250; 1350) of a wireless communication device (10, 100; 1200; 1300; 1404, 1406) operating in a wireless communication network, whereby execution of the program code causes the wireless communication device (10, 100; 1200; 1300; 1404, 1406) to perform a method according to any one of claims 1 to 56.

Images