WO2020167188A1

WO2020167188A1 - Pdcp entity, rlc entity and methods performed therein for providing multi connectivity

Info

Publication number: WO2020167188A1
Application number: PCT/SE2019/051305
Authority: WO
Inventors: Nianshan SHI; Jose Luis Pradas
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2019-02-14
Filing date: 2019-12-18
Publication date: 2020-08-20

Abstract

A method performed by a packet data convergence protocol (PDCP) entity providing multi connectivity to a wireless device in a wireless communication network. The PDCP entity transmits (S310) to one or more radio link control (RLC) entities, downlink (DL) PDCP protocol data units (PDUs) which are intended to be delivered to the wireless device. The one or more RLC entities are associated with the multi connectivity. Each DL PDCP PDU has a PDCP sequence number (SN). The PDCP entity receives (S320) information from at least one of the one or more RLC entities. The information indicates one or more of the transmitted DL PDCP PDUs that have been successfully, but not-in-sequence, delivered to the wireless device.

Description

PDCP ENTITY, RLC ENTITY AND METHODS PERFORMED THEREIN FOR PROVIDING MULTI CONNECTIVITY

TECHNICAL FIELD

Embodiments herein relate to a packet data convergence protocol (PDCP) entity, a radio link control (RLC) entity and methods performed therein. Furthermore, a computer program product and a computer readable storage medium are also provided herein. In particular, embodiments herein relate to multi connectivity.

BACKGROUND

In a typical wireless communication network, wireless devices, also known as wireless communication devices, mobile stations, stations (STA) and/or user equipments (UE), communicate via a Radio Access Network (RAN) to one or more core networks (CNs). The RAN covers a geographical area which is divided into service areas or cells, with each service area or cell being served by a radio network node such as a radio access node e.g., a Wi-Fi access point or a radio base station (RBS), which in some networks may also be denoted, for example, a“NodeB” (NB) or“eNodeB” (eNB),“gNodeB” (gNB), or NG-RAN node. A service area or cell is a geographical area where radio coverage is provided by the radio network node. The radio network node communicates over an air interface operating on radio frequencies with the wireless device within range of the radio network node.

A Universal Mobile Telecommunications System (UMTS) is a third generation (3G) telecommunication network, which evolved from the second generation (2G) Global System for Mobile Communications (GSM). The UMTS terrestrial radio access network (UTRAN) is essentially a RAN using wideband code division multiple access (WCDMA) and/or High Speed Packet Access (HSPA) for wireless devices. In a forum known as the Third Generation Partnership Project (3GPP), telecommunications suppliers propose and agree upon standards for third generation networks, and investigate enhanced data rate and radio capacity. In some RANs, e.g. as in UMTS, several radio network nodes may be connected, e.g., by landlines or microwave, to a controller node, such as a radio network controller (RNC) or a base station controller (BSC), which supervises and coordinates various activities of the plural radio network nodes connected thereto. This type of connection is sometimes referred to as a backhaul connection. The RNCs and BSCs are typically connected to one or more core networks.

Specifications for the Evolved Packet System (EPS), also called a Fourth Generation (4G) network, have been completed within the 3^rd Generation Partnership Project (3GPP) and this work continues in the coming 3GPP releases, for example to specify a Fifth

Generation (5G) network. The EPS comprises the Evolved Universal Terrestrial Radio Access Network (E-UTRAN), also known as the Long Term Evolution (LTE) radio access network, and the Evolved Packet Core (EPC), also known as System Architecture

Evolution (SAE) core network. E-UTRAN/LTE is a variant of a 3GPP radio access network wherein the radio network nodes are directly connected to the EPC core network rather than to RNCs. In general, in E-UTRAN/LTE the functions of an RNC are distributed between the radio network nodes, e.g. eNodeBs in LTE, and the core network. As such, the RAN of an EPS has an essentially“flat” architecture comprising radio network nodes connected directly to one or more core networks, i.e. they are not connected to RNCs. To compensate for that, the E-UTRAN specification defines a direct interface between the radio network nodes, this interface being denoted the X2 interface. EPS is the Evolved 3GPP Packet Switched Domain. New generation radio (NR) is a new radio access technology being standardized in 3GPP.

Connectivity between a UE and more than one RAN cell group may be referred to as multi connectivity, such as Dual connectivity (DC).

DC is a feature that allows a UE to simultaneously receive and transmit to at least two different network points. The two different network points are usually denoted as master eNodeB (MeNB) and secondary eNodeB (SeNB). MeNBs serve a master cell group (MCG), and SeNBs serve a secondary cell group (SCG). It is assumed that the radio resource control (RRC) protocol, which is responsible for configuring the UE, is terminated within the MeNB. While the UE receives RRC control signaling via the MCG, it may receive user data via both MCG and SCG.

A UE may also be coupled to more than two nodes, in which case there may be more than one RAN SCG.

Figure 1a is a block diagram of a user plane protocol architecture in DC. The currently envisaged protocol architecture supports three types of radio bearers within an MeNB 21 and a SeNB 22. The three types of radio bearers are MCG bearer 30, SCG bearer 40, and split bearer over MCG and SCG 50. MCG bearer 30 involves PDCP entity 32 and radio link control (RLC) entity 34. SCG bearer 40 includes PDCP entity 42 and RLC entity 44. Split bearer 50 includes PDCP entity 52, RLC entity 54 and RLC entity 56. In the case of the split bearer 50, user data that is received by PDCP entity 52 may be split via both RLC entity 54 of MeNB 21 and RLC 56 entity of SeNB 22. It is envisaged that some PDCP packet data units (PDUs) may be transmitted to the MeNB RLC entity 54 and some may be transmitted to the SeNB RLC entity 56. Additionally, each bear also involves a physical layer (PHY) entity.

Duplication at PDCP entity 52 therefore enables PDCP entity 52 duplicate the PDUs via independent transmission paths (also referred to as transmission legs, or logical channels), each transmission path provides one connectivity. It is therefore used to increase reliability and reduces latency and is especially beneficial for ultra-reliable low latency (URLLC) services. When duplication occurs, the original PDCP PDU and the corresponding duplicate shall not be transmitted on the same carrier. The two different logical channels can either belong to the same MAC entity or to different ones. In the former case, logical channel mapping restrictions are used in MAC entity to ensure that the logical channel carrying the original PDCP PDUs and logical channel carrying the corresponding duplicates are not sent on the same carrier.

Due to the transmission delay of the backhaul link between MeNB 21 and SeNB 22, and different radio link conditions between MeNB 21 and the UE and SeNB 22 and the UE, the receiving PDCP entity 52 may receive PDUs out of order. To provide in-order delivery, PDCP entity may buffer received PDUs and reorder them, and assign a PDCP sequence number (SN) for each PDU. The PDUs may be assigned consecutive PDCP SNs.

Feedback, e.g., a downlink data delivery status (DDDS) frame, from the RLC entity 54 and/or RLC entity 56 is provided to the PDCP entity 52 The specification for the DDDS frame, i.e. , PDU Type 1 , can be found in 3GPP TS 38.425.

In the conventional solution, the DDDS frame is sent from the RLC entity 54 and/or RLC entity 56 to the PDCP entity 52. The DDDS frame in the NR user plane protocol includes, among the other elements, the below two information elements related to how the PDCP PDUs are delivered by the RLC layer.

• the highest NR PDCP PDU SN successfully delivered by the RLC entity in sequence to the UE among those NR PDCP PDUs received from the PDCP entity in RLC Acknowledged Mode (AM).

• the highest NR PDCP PDU SN transmitted by the PDCP entity to the RLC entity among those NR PDCP PDUs received from the PDCP entity. SUMMARY

An object of embodiments herein is to provide a mechanism for enhancing the efficiency of duplicating a PDCP PDU.

According to an aspect the object is achieved by providing a method performed by a packet data convergence protocol (PDCP) entity providing multi connectivity to a wireless device in a wireless communication network, comprising: receiving information indicating one or more of the transmitted DL PDCP PDUs which have been successfully but not-in- sequence delivered to the wireless device, from at least one of the one or more RLC entities.

According to another aspect the object is achieved by providing a method performed by a radio link control (RLC) entity which is associated with multi connectivity, comprising: transmitting, in response to received DL PDCP PDUs, information indicating one or more of the received DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device to the PDCP entity.

According to still another aspect the object is achieved by providing a packet data convergence protocol (PDCP) entity for providing multi connectivity to a wireless device in a wireless communication network, configured to receive information indicating one or more of the transmitted DL PDCP PDUs which have been successfully but not-in- sequence delivered to the wireless device, from at least one RLC entity.

According to yet another aspect the object is achieved by providing a radio link control (RLC) entity which is associated with one of a multi connectivity, configured to transmit, in response to received DL PDCP PDUs, information indicating one or more of the received DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device to a PDCP entity.

It is furthermore provided herein a computer program product comprising instructions, which, when executed on at least one processor, cause the at least one processor to carry out any of the methods above, as performed by the PDCP entity or the RLC entity. It is additionally provided herein a computer-readable storage medium, having stored there on a computer program product comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to any of the methods above, as performed by the PDCP entity or the RLC entity. According to still another aspect the object is achieved by providing a PDCP entity or a radio network node comprising processing circuitry configured to receive information indicating one or more of the transmitted DL PDCP PDUs which have been successfully but not-in-sequence delivered to a wireless device, from at least one RLC entity.

According to still another aspect the object is achieved by providing a RLC entity or a radio network node comprising processing circuitry configured to transmit, in response to received DL PDCP PDUs, information indicating one or more of the received DL PDCP PDUs which have been successfully but not-in-sequence delivered to a wireless device to a PDCP entity.

Embodiments herein bring the advantage of improving the efficiency of DL PDCP PDU duplication. Thanks to the information indicating the DL PDCP PDUs which were successfully but not-in-sequence delivered, the PDCP entity is aware of and duplicate only those DL PDCP PDUs not successfully delivered. More effective duplication of the DL PDCP PDUs in multi connectivity is therefore achieved.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described in more detail in relation to the enclosed drawings, in which:

Figure 1a is a schematic overview depicting a user plane protocols for multi connectivity according to embodiments herein;

Figure 1 b is a schematic depicting a wireless communication network for multi connectivity according to embodiments herein;

Figure 1c is a schematic overview depicting embodiments of a wireless

communication network for multi connectivity;

Figure 2 is a schematic combined signaling scheme and flowchart according to embodiments herein;

Figure 3 is a flowchart depicting a method performed by a PDCP entity according to embodiments herein;

Figure 4 is a flowchart depicting a method performed by a first or second RLC entity according to embodiments herein; Figure 5 is a flowchart depicting a method performed by a third RLC entity according to embodiments herein;

Figure 6a is a schematic depicting a format of a DDDS frame according to embodiments herein;

Figure 6b-6c are schematics depicting example field values of a DDDS frame according to embodiments herein;

Figure 7 is a block diagram depicting a PDCP entity according to embodiments herein;

Figure 8 is a block diagram depicting a first or second RLC entity according to embodiments herein;

Figure 9 schematically illustrates a telecommunication network connected via an intermediate network to a host computer;

Figure 10 is a generalized block diagram of a host computer communicating via a base station with a user equipment over a partially wireless connection;

Figure 11-Figure 14 are flowcharts illustrating methods implemented in a communication system including a host computer, a base station and a user equipment.

DETAILED DESCRIPTION

As part of developing embodiments herein, a problem will first be identified and shortly discussed.

The conventional PDCP entity is aware of only the highest PDCP PDU SN successfully delivered in sequence by the RLC entity to the UE and the highest PDCP PDU SN transmitted by the PDCP entity to the RLC entity. The PDCP entity is not aware of the DL PDCP PDUs that are delivered successfully but not-in-sequence. Then the PDCP entity may duplicate all PCDP PDUs that between the above two numbers. The efficiency of duplicating PDCP PDU is therefore considerable low.

The embodiments herein provide to enhance the efficiency of packet duplication such as PDCP PDU duplication. During the developing embodiments herein, it is realized that the information on the PDCP PDUs successfully delivered but not-in-sequence, up to the highest transmitted PDCP PDU SN, is not reported from the RLC entity to the PDCP entity.

It is herein provided information from the RLC entity to the PDCP entity indicating the PDCP PDUs successfully delivered but not-in-sequence to the UE. Those PDCP PDU SNs are between the highest successfully delivered in-sequence PDCP PDU SN and the highest transmitted PDCP PDU SN. The PDCP entity or a node hosting the PDCP entity then is able to conclude which ones need to be duplicated and/or transmitted or retransmitted.

In other words, the embodiments provide that the RLC entity or a node hosting the RLC entity reports to the PDCP entity or a node hosting the PDCP entity the PDCP PDU SNs that are successfully not-in-sequence delivered, in addition to the existing highest successfully in-sequence delivered PDCP SN and the highest transmitted PDCP SN.

Embodiments herein relate to wireless communication networks in general. Figure 1 b is a schematic overview depicting a wireless communication network 100.

Network 100 includes one or more wireless device(s) 110 (which may be

interchangeably referred to as UEs 110), radio network node(s) and core network node(s) 120. A wireless device 110 may communicate with a radio network node over a wireless interface. For example, wireless device 110 may transmit wireless signals to one or more of radio network nodes 121 and 122, and/or receive wireless signals from one or more of radio network nodes 121 and 122. The wireless signals may contain voice traffic, data traffic, control signals, and/or any other suitable information. In some embodiments, an area of wireless signal coverage associated with a radio network node may be referred to as a cell. In some embodiments, wireless device 110 may have multi, e.g., DC capability. Thus, wireless device 110 may be able to receive signals from and/or transmit signals to at least two different network points simultaneously. For example, wireless device 110 may be able to receive signals from and/or transmit signals to radio network nodes 121 and 122 simultaneously.

Radio network nodes 121 and 122 may interface with core network node 120. In certain embodiments, radio network nodes 121 and 122 may interface with core network node 120 via an interconnecting network. The interconnecting network may refer to any interconnecting system capable of transmitting audio, video, signals, data, messages, or any combination of the preceding. In certain embodiments, radio network nodes 121 and 122 may interface with one or more radio network nodes over an internode interface 125. For example, network nodes 121 and 122 may interface over an X2 interface.

Figure 1c is a block diagram depicting the radio network node 121 such as the MeNB, and the radio network node 122 such as the SeNB. Split bearer includes PDCP entity 152, RLC entity 154 in the radio network node 121 and the RLC entity 156 in the radio network node 122.

The UE 110 may simultaneously receive and transmit to at least two different network points such as e.g. the first and second radio network nodes 121 and 122.. As described above, the two different network points may be denoted as MeNB and SeNB. In certain embodiments, radio network node 121 may be an MeNB, and radio network node 122 may be an SeNB. In such a case, radio network node 121 , as a MeNB, serves a master cell group (MCG), and the radio network node 122 such as the SeNB serves a secondary cell group (SCG). In certain embodiments, the RRC protocol, which is responsible for configuring UE 110, is terminated within the radio network node 121 such as the MeNB. While the UE 110 receives RRC control signaling via the MCG, it may receive user data via both MCG and SCG.

In operation, radio network node 121 such as the MeNB may receive user data for UE 110. In other words, the radio network node 121 such as the MeNB 121 may receive one or more PDCP PDUs to send to UE 110. The radio network node 121 such as the MeNB 121 may communicate one or more PDCP PDUs to UE 110, and may send one or more PDCP PDUs to the radio network node 122 such as the SeNB so that the SeNB 122 can transmit them to UE 110. The PDCP PDUs sent to the radio network node 122 such as the SeNB 122 may have PDCP SNs.

The core network (CN) may be a 5GCs. The wireless communication network 100 may use one or more technologies, such as Wi-Fi, Long Term Evolution (LTE), LTE-Advanced, 5G, Wideband Code Division Multiple Access (WCDMA), Global System for Mobile communications/Enhanced Data rate for GSM Evolution (GSM/EDGE), Worldwide

Interoperability for Microwave Access (WiMax), or Ultra Mobile Broadband (UMB), just to mention a few possible implementations. Embodiments herein relate to recent technology trends that are of particular interest in a 5G context, however, embodiments are applicable also in further development of the existing communication systems such as e.g. 3G and LTE.

The wireless devices e.g. a wireless device 110, also referred to as the UE 110, such as a mobile station, a non-access point (non-AP) station (STA), a STA, a user equipment and/or a wireless terminal, are connected via the one or more RANs, to the one or more CNs, e.g., 5GCs. It should be understood by those skilled in the art that“wireless device” is a non-limiting term which means any terminal, wireless communication terminal, communication equipment, Machine Type Communication (MTC) device, Device to Device (D2D) terminal, or user equipment e.g. smart phone, laptop, mobile phone, sensor, relay, mobile tablets or any device communicating within a cell or service area. The wireless device searches for carriers using a carrier raster. The carrier raster indicating possible frequency positions of a carrier for the wireless device.

The radio network nodes 121 and 122 are exemplified herein as RAN nodes providing radio coverage over a geographical area, a first service area and a second service area (not shown), of a radio access technology (RAT), such as NR, LTE, UMTS, Wi-Fi or similar. The radio network nodes 121 and 122 may be a radio access network node such as radio network controller or an access point such as a wireless local area network (WLAN) access point or an Access Point Station (AP STA), an access controller, a base station, e.g. a radio base station such as a NodeB, a gNodeB, an evolved Node B (eNB, eNodeB), a base transceiver station, Access Point Base Station, base station router, a transmission arrangement of a radio base station, a stand-alone access point or any other network unit capable of serving a wireless device 110 within the service areas served by the radio network nodes 121 and 122 depending e.g. on the radio access technology and terminology used and may be denoted as a receiving radio network node.

The method actions performed by the PDCP entity 152 for providing multi connectivity to the wireless device 110 in according to embodiments herein will now be described with reference to Figure 2 which is a schematic combined signaling scheme and flowchart, together with a flowchart depicted in Figure 3. The actions do not have to be taken in the order stated below, but may be taken in any suitable order. Actions performed in some embodiments may be marked with dashed boxes.

It is noted that the present disclosure applies to multi connectivity. In embodiment herein, three RLC entities 154, 156 and 158, which correspond to three transmission legs respectively, are used as an unlimited example. The skilled person will appreciate that the embodiments here also applies to scenario with only two RLC entities, i.e., DC.

Action S310.

In embodiments herein, the PDCP entity 152 may transmit DL PDCP PDUs to one or more RLC entities, e.g., first RLC entity 154 and optional second RLC entity 156.

The DL PDCP PDUs are intended to be delivered to the wireless device 110. I.e. they will be transmitted to the wireless device 110 along the one or two transmission legs.

Each RLC entity belongs to one transmission leg. As discussed in Figure 1a, each RLC entity is associated with one connectivity, respectively.

Each DL PDCP PDU have a PDCP SN. The DL PDCP PDUs may be assigned consecutive PDCP SNs by the PDCP entity 152.

When the DL PDCP PDUs are transmitted to more RLC entities, the transmitting action S310 herein may further comprise duplicating the DL PDCP PDUs.

The DL PDCP PDUs may be duplicated for only RLC entity(ies) involved in the transmission action S310, or alternatively, for all RLC entities involved in the multi connectivity.

The duplicated DL PDCP PDU may be assigned a same PDCP SN as an original DL PDCP PDU, but not mandatory.

The DL PDCP PDUs herein may be the same as the prior art DL PDCP PDUs. It is noted that the present application applies to any number of transmission legs, any way of duplicating a DL PDCP PDU and any way of assigning the PDCP SN.

Action S320.

After the DL PDCP PDUs have been transmitted to the RLC entities 154, 156, 158, the RLC entities 154, 156, 158 will forward them along the transmission legs to the wireless device 110. Then a feedback will be returned by the wireless device 110 to tell the RLC entities 154, 156, 158 which DL PDCP PDUs have been successfully delivered even though delivered not-in-sequence. Based on the feedback from the wireless device 110, the RLC entities 154, 156, 158 will know information indicating DL PDCP PDU(s) which has/have been successfully but not-in-sequence delivered to the wireless device 110 and send the information to the PDCP entity 152.

Then the PDCP entity 152 will receive the information, i.e. , feedback information, from at least one of the one or more RLC entities, e.g., first RLC entity 154 and optional second RLC entity 156. The information indicates one or more of the transmitted DL PDCP PDUs which have been successfully, but not-in-sequence, delivered to the wireless device 110, from at least one of the one or more RLC entities 154, 156, 158.

Thanks to the information indicating the DL PDCP PDUs which were successfully but not- in-sequence delivered, the PDCP entity 152 is aware of and will duplicate only those DL PDCP PDUs that was not successfully delivered. More effective duplication of the DL PDCP PDUs in multi connectivity is therefore achieved.

The information may be carried or reflected in a DDDS frame sent by the first RLC entity 154. Another similarly information may also be sent by the second RLC entity 156 if DL PDCP PDUs have been transmitted to the second RLC entity 156 as well.

The information may be PDCP SN(s) used to indicate the successfully but not-in- sequence delivered DL PDCP PDU(s).

The information may e.g. be defined by one or more of the following sub information:

- a flag indicating a presence of block(s) specifying DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device 10;

- a length field indicating how many blocks; or

for each block,

-a starting field indicating a start of the block; and

- a size field indicating a size of the block.

E.g., the PDCP PDUs starting from the“starting field” up to the size field are in need of being delivered in-sequence.

Action S330.

Based on the information, the PDCP entity 152 may determine which one or more DL PDCP PDUs that have not been successfully delivered to the wireless device 110. Since the information indicates the successfully though not-in-sequence delivered DL PDCP PDUs, the PDCP entity 152 is enabled to figure out which DL PDCP PDUs have not been successfully delivered to the wireless device 110.

Action S340.

If the DL PDCP PDUs have been duplicated at the action S310 for all RLC entity associated with the multi connectivity, then at action S340 no need to duplicate the DL PDCP PDU(s) any more.

Alternatively, the PDCP entity 152 may duplicate the DL PDCP PDU(s) which has/have not been successfully delivered to the wireless device 110.

Then the PDCP entity 152 may transmit the duplicated DL PDCP PDU(s) which has/have not been successfully delivered to the wireless device 110 to RLC entity(ies), e.g., a third RLC entity 158, which may be different from the above one or more RLC entities, e.g., first RLC entity 154 and second RLC entity 156.

A different RLC, e.g., third RLC entity 158 which is associated with another connectivity, may improve the robustness and reliability of the transmitting the DL PDCP PDUs.

In the case each RLC entity is within one cell. The above one or more RLC entities, e.g., first RLC entity 154 and second RLC entity 156 may belong to either a same cell or different cells, respectively. Meanwhile, the other RLC entity, e.g., the third RLC entity 158, may be associated with a cell different from the first RLC entity 154 and second RLC entity 156. Thus the robustness and reliability of the transmitting the DL PDCP PDUs will be further improved.

Optionally, each PDU may have a delay time budget. If a confirmation of a reception of the PDU from the first RLC entity 154 and/or second RLC entity 156 has not been received before a duplication timer t_duplicate, delay time budget minus delta time, is consumed, the PDCP entity 152 may determine to duplicate the not successfully delivered DL PDCP PDU(s).

Embodiments herein bring the advantage of improving the efficiency of DL PDCP PDU duplication. Thanks to the information indicating the DL PDCP PDUs which were successfully but not-in-sequence delivered, the PDCP entity 152 is enabled to aware and duplicate only those DL PDCP PDUs not successfully delivered. More effective

duplication of the DL PDCP PDUs in multi connectivity is therefore achieved. The method actions performed by the first radio link control (RLC) entity 154 which is associated with multi connectivity will be explained herein with reference to a flowchart depicted in Figure 4, together with Figure 2. The actions do not have to be taken in the order stated below, but may be taken in any suitable order. Actions performed in some embodiments may be marked with dashed boxes. If a duplicated DL PDCP PDU is transmitted to the second RLC entity 156, the second RLC entity 156 will perform the same method as below.

Action S410.

The first RLC entity 154 may receive the DL PDCP PDUs which are intended to be delivered to a wireless device 110 from the PDCP entity 152 providing the multi connectivity to the wireless device 110 in a wireless communication network 100.

After the DL PDCP PDUs have been received by the first RLC entity 154, the first RLC entity 154 will transmit them along its transmission leg to the wireless device 110. Then a feedback will be returned by the wireless device 110 to tell the first RLC entity 154 which DL PDCP PDUs have been successfully delivered even though delivered not-in-sequence.

Action S420.

Based on the feedback from the wireless device 110, the first RLC entity 154 will transmit the information to the PDCP entity 152 in action S420.

Thus in response to the received DL PDCP PDUs, the first RLC entity 154 transmits the information to the PDCP entity 152. The information indicates which one or more of the received DL PDCP PDUs that have been successfully, but not-in-sequence, delivered to the wireless device (110).

As discussed above, the information may be carried in DDDS frame generated by the first RLC entity 154 and/or second RLC entity 156. The information may be PDCP SN(s), used to indicate the successfully but not-in-sequence delivered DL PDCP PDU(s).

Given that the PDCP entity 152 knows the PDCP PDUs which have been successfully delivered to the wireless device 110, the PDCP entity 152 will know and duplicate only those PDCP PDUs not delivered. More effective duplication of the PDCP PDUs in multi connectivity is therefore achieved. The method actions performed by the third radio link control (RLC) entity 58 which is associated with multi connectivity will be explained herein with reference to a flowchart depicted in Figure 5, together with Figure 2.

Action S510.

The third RLC entity 158 receives PDCP PDU(s) has/have not been successfully delivered to the wireless device 10.

Later, the third RLC entity 158 will transmit them along its transmission leg to the wireless device 110. The third RLC entity 158 may be different from the first RLC entity 154 and second RLC entity 156. I.e., the third RLC entity 158 may be associated with another one of the multi connectivity. Thus the robustness and reliability of the transmitting the DL PDCP PDUs will be improved.

The third RLC entity 158 may be even associated with a cell different from the first RLC entity 154 and second RLC entity 156. Thus the robustness and reliability of the transmitting the DL PDCP PDUs will be further improved.

In the embodiments, some embodiments are described in context of NR, however the skilled person will appreciate that the embodiments herein are also applied to other wireless communication system.

An example of the DDDS frame, i.e., user plane protocol PDU Type 1 , which carries the above information, has been illustrated in Figure 6a. Definition for each existing field can be found in 3GPP TS 38.425. In the following we will focus on the newly added information according to the embodiments herein.

The DDDS frame may comprise a flag, e.g.“Delivered not-in-sequence PDCP SN Ind” which is introduced to indicate if the“PDCP PDUs successfully not-in-sequence delivered” block is included or not. A length field is introduced to indicate how many of such blocks are included and a block with PDCP PDU SN value and block size are included to mark the start and the size of the block. The PDCP PDU SNs from “Successfully not-in- sequence delivered PDCP PDU SN start” up to“Successfully not-in-sequence delivered PDCP PDU SN start+ Successfully not-in-sequence delivered Block size” are consider to be successfully delivered in-sequence. The skilled person will appreciate that Figure 6a is a non-limiting example of an enhanced DDDS frame, the above one or more fields may be placed in any location and sequence.

Another embodiment in the context of the DDDS frame is provided herein. Assuming the above three transmission legs are involved in the duplication, the first RLC entity 154 feedbacks to the PDCP entity 152 in DDDS frame the highest successfully in-sequence delivered is PDCP PDU sn, the highest transmitted is sn+5, in addition, sn+2, sn+4 are successfully delivered. Figure 6b shows example values in the corresponding information elements (lEs), specifically, the flag is set true, i.e., 1 , the length field indicates 2 in octets, i.e., 00000010 in binary, blocks, the PDCP SN values sn+2, sn+4 are included in each starting field, the size field is 1 in octets, i.e., 00000001 in binary. The highest successfully in-sequence delivered PDCP PDU sn (not shown), and the highest transmitted sn+5 (not shown) will be indicated as usual in the frame.

The second RLC entity 156 feedbacks that the highest successfully in-sequence delivered is PDCP PDU sn+1 , the highest transmitted is sn+5, in addition, sn+3, is successfully delivered. As shown in Figure 6c, the difference from Figure 6b is that the length field indicates 1 in octets, i.e., 00000001 in binary, since only PDCP PDU sn+3 is successfully but not-in-sequence delivered, and the PDCP SN value sn+3 is included with a size of 1 in octets, i.e., 00000001 in binary.

The PDCP entity 152 is then enabled thus to conclude that the PDCP PDUs are successfully delivered in-sequence up to SN+4, and PDCP PDU sn+5 has not been successfully delivered to the wireless device 110. Accordingly, the PDCP entity 152 may only duplicate and transmit the PDCP PDU sn+5 to the third RLC entity 158.

Figure 7 is a block diagram depicting the PDCP entity 152 for providing multi connectivity to a wireless device 110 in a wireless communication network 100 according to embodiments herein.

The PDCP entity 152 may comprise processing circuitry 701 , e.g. one or more processors, configured to perform the methods herein.

The PDCP entity 152 may comprise a duplicating module 712. The PDCP entity 152, the processing circuitry 701 and/or the duplicating module 712 may be configured to duplicate the DL PDCP PDUs for each RLC entity associated with the multi connectivity. The PDCP entity 152 may comprise a transmitting module 710, e.g., a transmitter or transceiver. The PDCP entity 152, the processing circuitry 701 , and/or transmitting module may be configured to transmit the DL PDCP PDUs which are intended to be delivered to the wireless device 110 to one or more radio link control (RLC) entities which are associated with the multi connectivity, each DL PDCP PDU having a PDCP SN. The DL PDCP PDUs may have consecutive PDCP SNs. Specifically, the PDCP entity 152, the processing circuitry 701 , and/or transmitting module may be configured to transmit one copy of the DL PDCP PDUs to each RLC entity.

The PDCP entity 152 comprises a receiving module 713, e.g. a receiver or transceiver. The PDCP entity 152, the processing circuitry 701 and/or the receiving module 713 is configured to receive the information indicating one or more of the transmitted DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device 110, from at least one of the one or more RLC entities. The PDCP entity 152, the processing circuitry 701 , and/or the receiving module 713 may be configured to receive the information from at least one of the one or more RLC entities by: receiving at least one DDDS frame from at least one of the one or more RLC entities. The information may comprise one or more PDCP SNs

The PDCP entity 152 may comprise a determining module 711. The PDCP entity 152, the processing circuitry 701 and/or the determining module 711 may be configured to determine the one or more DL PDCP PDUs which have been transmitted to the one or more RLC entities but not successfully delivered to the wireless device 110 based on the information.

The PDCP entity 152, the processing circuitry 701 , and/or transmitting module 710 may further be configured to transmit the duplicated the one or more DL PDCP PDUs which are not successfully delivered to the wireless device 110 to a RLC entity, which may be a different RLC entity being associated with a different connectivity. The different RLC entity may be associated with a cell different from the one or more RLC entities.

The PDCP entity 152 may further comprise a memory 704. The memory comprises one or more units to be used to store data on, such as the information, PDCP PDU(s) and/or PDCP SN(s) to perform the methods disclosed herein when being executed, and similar. Thus, the PDCP entity 152 may comprise the processing circuitry and the memory, said memory comprising instructions executable by said processing circuitry whereby said PDCP entity 152 is operative to perform the methods herein. The methods according to the embodiments described herein for the PDCP entity 152 are respectively implemented by means of e g. a computer program 705 or a computer program product 705, comprising instructions, i.e. , software code portions, which, when executed on at least one processor, cause the at least one processor to carry out the actions described herein, as performed by the PDCP entity 152. The computer program product 705 may be stored on a computer-readable storage medium 706, e g. a disc, USB or similar. The computer-readable storage medium 706, having stored thereon the computer program product 705, may comprise the instructions which, when executed on at least one processor, cause the at least one processor to carry out the actions described herein, as performed by the PDCP entity 152. In some embodiments, the computer- readable storage medium may be a non-transitory computer-readable storage medium.

Figure 8 is a block diagram depicting by the first RLC entity 154 or second RLC entity 156 which is associated with one of the multi connectivity according to embodiments herein.

The first RLC entity 154 or second RLC entity 156 may comprise processing circuitry 801 , e.g. one or more processors, configured to perform the methods herein.

The first RLC entity 154 or second RLC entity 156 may comprise a receiving module 810, e.g. a receiver or transceiver. The first RLC entity 154 or second RLC entity 156, the processing circuitry 801 and/or the receiving module 810 may be configured to receive the DL PDCP PDUs which are intended to be delivered to a wireless device 110 from a PDCP entity 152 providing the multi connectivity to the wireless device 110 in a wireless communication network, each DL PDCP PDU having a PDCP SN. The DL PDCP PDUs may have consecutive PDCP SNs.

The first RLC entity 154 or second RLC entity 156 comprises a transmitting module 812, e.g., a transmitter or transceiver. The first RLC entity 154 or second RLC entity 156, the processing circuitry 801 and/or the transmitting module 812 is configured to transmit, in response to the received DL PDCP PDUs, the information indicating one or more of the received DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device 110 to the PDCP entity 152.

The first RLC entity 154 or second RLC entity 156, the processing circuitry 801 and/or the transmitting module 812 may be configured to transmit the information by using a DDDS frame. The first RLC entity 154 or second RLC entity 156may further comprise a memory 804. The memory comprises one or more units to be used to store data on, such as the information, PDCP PDU(s) and/or PDCP SN(s) to perform the methods disclosed herein when being executed, and similar. Thus, the first RLC entity 154 or second RLC entity 156 may comprise the processing circuitry and the memory, said memory comprising instructions executable by said processing circuitry whereby said first RLC entity 154 or second RLC entity 156 is operative to perform the methods herein.

The methods according to the embodiments described herein for the first RLC entity 154 or second RLC entity 156 are respectively implemented by means of e.g. a computer program 805 or a computer program product 805, comprising instructions, i.e. , software code portions, which, when executed on at least one processor, cause the at least one processor to carry out the actions described herein, as performed by the first RLC entity 154 or second RLC entity 156. The computer program product 805 may be stored on a computer-readable storage medium 806, e g. a disc or similar. The computer-readable storage medium 806, having stored thereon the computer program product 805, may comprise the instructions which, when executed on at least one processor, cause the at least one processor to carry out the actions described herein, as performed by the first RLC entity 154 or second RLC entity 156. In some embodiments, the computer-readable storage medium may be a non-transitory computer-readable storage medium.

As will be readily understood by those familiar with communications design, that functions means or modules may be implemented using digital logic and/or one or more microcontrollers, microprocessors, or other digital hardware. In some

embodiments, several or all of the various functions may be implemented together, such as in a single application-specific integrated circuit (ASIC), or in two or more separate devices with appropriate hardware and/or software interfaces between them. Several of the functions may be implemented on a processor shared with other functional components of a radio network node, for example.

Alternatively, several of the functional elements of the processing means discussed may be provided through the use of dedicated hardware, while others are provided with hardware for executing software, in association with the appropriate software or firmware. Thus, the term“processor” or“controller” as used herein does not exclusively refer to hardware capable of executing software and may implicitly include, without limitation, digital signal processor (DSP) hardware, read-only memory (ROM) for storing software, random-access memory for storing software and/or program or application data, and non volatile memory. Other hardware, conventional and/or custom, may also be included. Designers of radio network nodes will appreciate the cost, performance, and maintenance trade-offs inherent in these design choices.

According to an embodiment, a first radio access node, e.g., the radio network node 121 , may comprise/host the PDCP entity 152. A second radio access node may comprise at least one of the first RLC entity 154 and the second RLC entity 156. The second radio access node may be different from the first radio access node. A third radio access node, e.g., the radio network node 122, which may be different from the first and second radio access nodes may comprise the third RLC entity 158.

The nodes hosting the first RLC entity 154, second RLC entity 156 and third RLC entity 158 may be a mixture of LTE and NR radio access nodes, or only NR radio access nodes.

With reference to Figure 9, in accordance with an embodiment, a communication system includes a telecommunication network 3210, such as a 3GPP-type cellular network, which comprises an access network 3211 , such as a radio access network, and a core network 3214. The access network 3211 comprises a plurality of base stations 3212a, 3212b, 3212c, such as NBs, eNBs, gNBs or other types of wireless access points being examples of the radio network nodes herein, each defining a corresponding coverage area 3213a, 3213b, 3213c. Each base station 3212a, 3212b, 3212c is connectable to the core network 3214 over a wired or wireless connection 3215. A first user equipment (UE) 3291 , being an example of the wireless device 110, located in coverage area 3213c is configured to wirelessly connect to, or be paged by, the corresponding base station 3212c. A second UE 3292 in coverage area 3213a is wirelessly connectable to the corresponding base station 3212a. While a plurality of UEs 3291 , 3292 are illustrated in this example, the disclosed embodiments are equally applicable to a situation where a sole UE is in the coverage area or where a sole UE is connecting to the corresponding base station 3212.

The telecommunication network 3210 is itself connected to a host computer 3230, which may be embodied in the hardware and/or software of a standalone server, a cloud-implemented server, a distributed server or as processing resources in a server farm. The host computer 3230 may be under the ownership or control of a service provider, or may be operated by the service provider or on behalf of the service

provider. The connections 3221 , 3222 between the telecommunication network 3210 and the host computer 3230 may extend directly from the core network 3214 to the host computer 3230 or may go via an optional intermediate network 3220. The intermediate network 3220 may be one of, or a combination of more than one of, a public, private or hosted network; the intermediate network 3220, if any, may be a backbone network or the Internet; in particular, the intermediate network 3220 may comprise two or more sub-networks (not shown).

The communication system of Figure 9 as a whole enables connectivity between one of the connected UEs 3291 , 3292 and the host computer 3230. The connectivity may be described as an over-the-top (OTT) connection 3250. The host computer 3230 and the connected UEs 3291 , 3292 are configured to communicate data and/or signaling via the OTT connection 3250, using the access network 3211 , the core network 3214, any intermediate network 3220 and possible further infrastructure (not shown) as intermediaries. The OTT connection 3250 may be transparent in the sense that the participating communication devices through which the OTT connection 3250 passes are unaware of routing of uplink and downlink communications. For example, a base station 3212 may not or need not be informed about the past routing of an incoming downlink communication with data originating from a host computer 3230 to be forwarded (e.g., handed over) to a connected UE 3291. Similarly, the base station 3212 need not be aware of the future routing of an outgoing uplink communication originating from the UE 3291 towards the host computer 3230.

Example implementations, in accordance with an embodiment, of the UE, base station and host computer discussed in the preceding paragraphs will now be described with reference to Figure 10. In a communication system 3300, a host computer 3310 comprises hardware 3315 including a communication interface 3316 configured to set up and maintain a wired or wireless connection with an interface of a different communication device of the communication system 3300. The host computer 3310 further comprises processing circuitry 3318, which may have storage and/or processing capabilities. In particular, the processing circuitry 3318 may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. The host computer 3310 further comprises software 3311 , which is stored in or accessible by the host computer 3310 and executable by the processing circuitry 3318. The software 3311 includes a host application 3312. The host application 3312 may be operable to provide a service to a remote user, such as a UE 3330 connecting via an OTT connection 3350 terminating at the UE 3330 and the host computer 3310. In providing the service to the remote user, the host application 3312 may provide user data which is transmitted using the OTT connection 3350.

The communication system 3300 further includes a base station 3320 provided in a telecommunication system and comprising hardware 3325 enabling it to communicate with the host computer 3310 and with the UE 3330. The hardware 3325 may include a communication interface 3326 for setting up and maintaining a wired or wireless connection with an interface of a different communication device of the communication system 3300, as well as a radio interface 3327 for setting up and maintaining at least a wireless connection 3370 with a UE 3330 located in a coverage area (not shown in Figure 10) served by the base station 3320. The communication interface 3326 may be configured to facilitate a connection 3360 to the host computer 3310. The connection 3360 may be direct or it may pass through a core network (not shown in Figure 10) of the telecommunication system and/or through one or more intermediate networks outside the telecommunication system. In the embodiment shown, the hardware 3325 of the base station 3320 further includes processing circuitry 3328, which may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. The base station 3320 further has software 3321 stored internally or accessible via an external connection.

The communication system 3300 further includes the UE 3330 already referred to. Its hardware 3335 may include a radio interface 3337 configured to set up and maintain a wireless connection 3370 with a base station serving a coverage area in which the UE 3330 is currently located. The hardware 3335 of the UE 3330 further includes processing circuitry 3338, which may comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. The UE 3330 further comprises software 3331 , which is stored in or accessible by the UE 3330 and executable by the processing circuitry 3338. The software 3331 includes a client application 3332. The client application 3332 may be operable to provide a service to a human or non-human user via the UE 3330, with the support of the host computer 3310. In the host computer 3310, an executing host application 3312 may communicate with the executing client application 3332 via the OTT connection 3350 terminating at the UE 3330 and the host computer 3310. In providing the service to the user, the client application 3332 may receive request data from the host application 3312 and provide user data in response to the request data. The OTT connection 3350 may transfer both the request data and the user data. The client application 3332 may interact with the user to generate the user data that it provides.

It is noted that the host computer 3310, base station 3320 and UE 3330 illustrated in Figure 10 may be identical to the host computer 3230, one of the base stations 3212a, 3212b, 3212c and one of the UEs 3291 , 3292 of Figure 9, respectively. This is to say, the inner workings of these entities may be as shown in Figure 10 and independently, the surrounding network topology may be that of Figure 9.

In Figure 10, the OTT connection 3350 has been drawn abstractly to illustrate the communication between the host computer 3310 and the user equipment 3330 via the base station 3320, without explicit reference to any intermediary devices and the precise routing of messages via these devices. Network infrastructure may determine the routing, which it may be configured to hide from the UE 3330 or from the service provider operating the host computer 3310, or both. While the OTT connection 3350 is active, the network infrastructure may further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or

reconfiguration of the network).

The wireless connection 3370 between the UE 3330 and the base station 3320 is in accordance with the teachings of the embodiments described throughout this disclosure. One or more of the various embodiments improve the performance of OTT services provided to the UE 3330 using the OTT connection 3350, in which the wireless connection 3370 forms the last segment. More precisely, the teachings of these embodiments may enhance the efficiency of PDCP PDU duplication.

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 3350 between the host computer 3310 and UE 3330, in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring the OTT connection 3350 may be implemented in the software 3311 of the host computer 3310 or in the software 3331 of the UE 3330, or both. In

embodiments, sensors (not shown) may be deployed in or in association with communication devices through which the OTT connection 3350 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 3311 , 3331 may compute or estimate the monitored quantities. The reconfiguring of the OTT connection 3350 may include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect the base station 3320, and it may be unknown or imperceptible to the base station 3320. Such procedures and functionalities may be known and practiced in the art. In certain embodiments, measurements may involve proprietary UE signaling facilitating the host computer’s 3310 measurements of throughput, propagation times, latency and the like. The measurements may be implemented in that the software 3311 , 3331 causes messages to be transmitted, in particular empty or‘dummy’ messages, using the OTT connection 3350 while it monitors propagation times, errors etc.

Figure 11 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which may be those described with reference to Figure 9 and Figure 10. For simplicity of the present disclosure, only drawing references to Figure 11 will be included in this section. In a first step 3410 of the method, the host computer provides user data. In an optional substep 3411 of the first step 3410, the host computer provides the user data by executing a host application. In a second step 3420, the host computer initiates a transmission carrying the user data to the UE. In an optional third step 3430, the base station transmits to the UE the user data which was carried in the transmission that the host computer initiated, in accordance with the teachings of the embodiments described throughout this disclosure. In an optional fourth step 3440, the UE executes a client application associated with the host application executed by the host computer.

Figure 12 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which may be those described with reference to Figure 9 and Figure 10. For simplicity of the present disclosure, only drawing references to Figure 12 will be included in this section. In a first step 3510 of the method, the host computer provides user data. In an optional substep (not shown) the host computer provides the user data by executing a host application. In a second step 3520, the host computer initiates a transmission carrying the user data to the UE. The transmission may pass via the base station, in accordance with the teachings of the embodiments described throughout this disclosure. In an optional third step 3530, the UE receives the user data carried in the transmission. Figure 13 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which may be those described with reference to Figure 9 and Figure 10. For simplicity of the present disclosure, only drawing

references to Figure 13 will be included in this section. In an optional first step 3610 of the method, the UE receives input data provided by the host computer. Additionally or alternatively, in an optional second step 3620, the UE provides user data. In an optional substep 3621 of the second step 3620, the UE provides the user data by executing a client application. In a further optional substep 3611 of the first step 3610, the UE executes a client application which provides the user data in reaction to the received input data provided by the host computer. In providing the user data, the executed client application may further consider user input received from the user.

Regardless of the specific manner in which the user data was provided, the UE initiates, in an optional third substep 3630, transmission of the user data to the host computer. In a fourth step 3640 of the method, the host computer receives the user data transmitted from the UE, in accordance with the teachings of the embodiments described throughout this disclosure.

Figure 14 is a flowchart illustrating a method implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which may be those described with reference to Figure 9 and Figure 10. For simplicity of the present disclosure, only drawing

references to Figure 14 will be included in this section. In an optional first step 3710 of the method, in accordance with the teachings of the embodiments described

throughout this disclosure, the base station receives user data from the UE. In an optional second step 3720, the base station initiates transmission of the received user data to the host computer. In a third step 3730, the host computer receives the user data carried in the transmission initiated by the base station.

It will be appreciated that the foregoing description and the accompanying drawings represent non-limiting examples of the methods and apparatus taught herein. As such, the apparatus and techniques taught herein are not limited by the foregoing description and accompanying drawings. Instead, the embodiments herein are limited only by the following claims and their legal equivalents.

Some more Embodiments Group A Embodiments

1. A method performed by a packet data convergence protocol, PDCP, entity providing multi connectivity to a wireless device in a wireless communication network, comprising:

- transmitting (S310) downlink, DL, PDCP protocol data units, PDUs, which are intended to be delivered to the wireless device to one or more radio link control, RLC, entities which are associated with the multi connectivity, each DL PDCP PDU having a PDCP sequence number, SN; and

- receiving (S320) information indicating one or more of the transmitted DL PDCP PDUs which have been successfully, but not-in-sequence, delivered to the wireless device, from at least one of the one or more RLC entities.

2. The method according to the embodiment 1 , wherein receiving (S320) the information from at least one of the one or more RLC entities comprises: receiving at least one Downlink Data Delivery Status, DDDS, frame from at least one of the one or more RLC entities.

3. The method according to any one of the embodiments 1-2, wherein the information comprises one or more PDCP SNs.

4. The method according to any one of the embodiments 1-3, further comprising:

- determining (S330) one or more DL PDCP PDUs which have been transmitted to the one or more RLC entities but not successfully delivered to the wireless device based on the information; or

- duplicating and/or transmitting or retransmitting (S340) one or more DL PDCP PDUs which have been transmitted to the one or more RLC entities but not successfully delivered to the wireless device to a RLC entity, which may be a different RLC entity being associated with a different connectivity.

5. The method according to the embodiment 4, wherein the different RLC entity is associated with a cell different from the one or more RLC entities.

6. The method according to any one of the embodiments 1-5, wherein the information indicating one or more of the transmitted DL PDCP PDUs which have been successfully, but not-in-sequence, delivered to the wireless device comprises one or more of: - a flag indicating the presence of the block(s) indicating DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device;

- a length field indicating how many blocks; or

for each block,

-a starting field indicating a start of the block; and

- a size field indicating a size of the block.

7. The method according to any one of the embodiments 1-6, when transmitting (S310) the DL PDCP PDUs to more RLC entities, wherein transmitting (S310) the DL PDCP PDUs further comprises duplicating the DL PDCP PDUs for each RLC entity.

8. The method according to the embodiment 7, wherein the duplicated DL PDCP

PDUs at the transmitting (S310) action have a same PDCP SN.

Group B Embodiments

9. A method performed by a radio link control, RLC, entity which is associated with multi connectivity, comprising:

- receiving (S410) downlink, DL, packet data convergence protocol, PDCP, packet data units, PDUs, which are intended to be delivered to a wireless device from a PDCP entity providing the multi connectivity to the wireless device in a wireless communication network, each DL PDCP PDU having a PDCP sequence number, SN; and

- transmitting (S420), in response to the received DL PDCP PDUs, information indicating one or more of the received DL PDCP PDUs which have been successfully, but not-in-sequence, delivered to the wireless device to the PDCP entity.

10. The method according to the embodiment 9, wherein transmitting (S420) the information comprises: transmitting a Downlink Data Delivery Status, DDDS, frame.

11. The method according to any one of the embodiments 9-10, wherein the information comprises one or more PDCP SNs.

12. The method according to any one of the embodiments 9-11 , wherein the information indicating one or more of the transmitted DL PDCP PDUs which have been successfully, but not-in-sequence, delivered to the wireless device comprises one or more of: - a flag indicating a presence of one or more blocks specifying DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device;

- a length field indicating how many blocks; or

for each block,

-a starting field indicating a start of the block; and

- a size field indicating a size of the block.

Group C Embodiments

13. A packet data convergence protocol, PDCP, entity for providing multi connectivity to a wireless device in a wireless communication network, configured to:

- transmit downlink, DL, PDCP protocol data units, PDUs, which are intended to be delivered to the wireless device to one or more radio link control, RLC, entities which are associated with the multi connectivity, each DL PDCP PDU having a PDCP sequence number, SN; and

- receive information indicating one or more of the transmitted DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device, from at least one of the one or more RLC entities.

14. The PDCP entity according to the embodiment 13, wherein the PDCP entity is configured to receive the information from at least one of the one or more RLC entities by: receiving at least one Downlink Data Delivery Status, DDDS, frame from at least one of the one or more RLC entities.

15. The PDCP entity according to any one of the embodiments 13-15, wherein the information comprises one or more PDCP SNs.

16. The PDCP entity according to any one of the embodiments 12-15, the PDCP entity is further configured to:

- determine one or more DL PDCP PDUs which have been transmitted to the one or more RLC entities but not successfully delivered to the wireless device based on the information; or

- duplicate and transmit one or more DL PDCP PDUs which have been transmitted to the one or more RLC entities but not successfully delivered to the wireless device to a RLC entity, which may be a different RLC entity being associated with a different connectivity.

17. The PDCP entity according to the embodiment 16, wherein the different RLC entity is associated with a cell different from the one or more RLC entities.

18. The PDCP entity according to any one of the embodiments 13-17, wherein the information indicating one or more of the transmitted DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device comprises one or more of:

- a flag indicating a presence of one or more blocks specifying DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device;

- a length field indicating how many blocks; or

for each block,

-a starting field indicating a start of the block; and

- a size field indicating a size of the block.

19. The PDCP entity according to any one of the embodiments 13-18, when the PDCP entity is configured to transmit the DL PDCP PDUs to more RLC entities, the PDCP entity is further configured to duplicate the DL PDCP PDUs for each RLC entity and transmit one copy of the DL PDCP PDUs to each RLC entity.

20. The PDCP entity according to the embodiment 19, wherein the duplicated DL PDCP PDUs have a same PDCP SN.

21. A packet data convergence protocol, PDCP, entity for providing multi connectivity to a wireless device in a wireless communication network, comprising a processor configured to:

- transmit downlink (DL) PDCP protocol data units, PDUs, which are intended to be delivered to the wireless device to one or more radio link control, RLC, entities which are associated with the multi connectivity, each DL PDCP PDU having a PDCP SN; and

22. A radio access node comprises a packet data convergence protocol, PDCP, entity according to any one of the embodiments 13-21. Group D Embodiments

23. A radio link control, RLC, entity which is associated with multi connectivity, configured to:

- receive downlink, DL, packet data convergence protocol, PDCP, packet data units,

PDUs, which are intended to be delivered to a wireless device from a PDCP entity providing the multi connectivity to the wireless device in a wireless communication network, each DL PDCP PDU having a PDCP sequence number, SN; and

- transmit, in response to the received DL PDCP PDUs, information indicating one or more of the received DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device to the PDCP entity.

24. The method according to the embodiment 23, wherein the RLC entity is configured to transmit the information by: transmitting a Downlink Data Delivery Status, DDDS, frame.

25. The method according to any one of the embodiments 23-25, wherein the information comprises one or more PDCP SNs.

26. The method according to any one of the embodiments 23-25, wherein the information indicating one or more of the transmitted DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device comprises one or more of:

- a length field indicating how many blocks; or

for each block,

-a starting field indicating a start of the block; and

- a size field indicating a size of the block.

27. A radio link control, RLC, entity which is associated with multi connectivity, comprising a processor configured to perform any one of:

- receive downlink, DL, packet data convergence protocol, PDCP, packet data units, PDUs, which are intended to be delivered to a wireless device from a PDCP entity providing the multi connectivity to the wireless device in a wireless communication network, each DL PDCP PDU having a PDCP SN; and

28. A radio access node comprises at least one radio link control, RLC, entity according to any one of the embodiments 23-27.

Group E Embodiments

29. A wireless communication network comprises a radio access network comprising first radio access node according to the embodiment 22 and a second radio access node according to the embodiment 28.

30. A computer program product comprising instructions, which, when executed on at least one processor, cause the at least one processor to carry the method according to any of the embodiments 1-12, as performed by the PDCP entity or RLC entity.

31. A computer-readable storage medium, having stored thereon a computer program product comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method according to any of the embodiments 1-12, as performed by the PDCP entity or RLC entity.

Claims

1. A method performed by a packet data convergence protocol, PDCP, entity (152) providing multi connectivity to a wireless device (110) in a wireless communication network, comprising:

- transmitting (S310) to one or more radio link control, RLC, entities (154, 156, 158), downlink, DL, PDCP protocol data units, PDUs, which are intended to be delivered to the wireless device (110), wherein the one or more RLC entities (154, 156, 158) are associated with the multi connectivity, each DL PDCP PDU having a

PDCP sequence number, SN; and

- receiving (S320) information indicating one or more of the transmitted DL PDCP PDUs which have been successfully, but not-in-sequence, delivered to the wireless device (110), from at least one of the one or more RLC entities (154, 156, 158).

2. The method according to the claim 1 , wherein receiving (S320) the information from at least one of the one or more RLC entities (154, 156, 158) comprises:

receiving at least one Downlink Data Delivery Status, DDDS, frame from at least one of the one or more RLC entities (154, 156, 158).

3. The method according to any one of the claims 1-2, wherein the information

comprises one or more PDCP SNs.

4. The method according to any one of the claims 1-3, further comprising

- determining (S330) one or more DL PDCP PDUs which have been transmitted to the one or more RLC entities (154, 156, 158) but not successfully delivered to the wireless device (110) based on the information; and/or

- duplicating and/or transmitting or retransmitting (S340) one or more DL PDCP PDUs which have been transmitted to the one or more RLC entities (154,

156, 158) but not successfully delivered to the wireless device (110) to an RLC entity (154), which may be a different RLC entity being associated with a different connectivity.

5. The method according to the claim 4, wherein the different RLC entity is associated with a cell different from the one or more RLC entities (154, 156, 158).

6. The method according to any one of the claims 1-5, wherein the information

indicating one or more of the transmitted DL PDCP PDUs which have been successfully, but not-in-sequence, delivered to the wireless device (110) comprises one or more of:

- a flag indicating the presence of the block(s) indicating DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device (1 10);

- a length field indicating how many blocks; or

for each block,

-a starting field indicating a start of the block; and

- a size field indicating a size of the block.

7. The method according to any one of the claims 1-6, when transmitting (S310) the DL PDCP PDUs to more RLC entities (154, 156, 158), wherein transmitting (S310) the DL PDCP PDUs further comprises duplicating the DL PDCP PDUs for each RLC entity (154, 156, 158).

8. The method according to the claim 7, wherein the duplicated DL PDCP PDUs at the transmitting (S310) action have a same PDCP SN.

9. A computer program comprising instructions, which when executed by a processor, causes the processor to perform actions according to any of the claims 1-8.

10. A carrier comprising the computer program of claim 9, wherein the carrier is one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or a computer-readable storage medium.

11. A method performed by a radio link control, RLC, entity (154) which is associated with multi connectivity, comprising:

- receiving (S410) from a PDCP entity (152) providing the multi connectivity to a wireless device (110) in a wireless communication network, downlink, DL, packet data convergence protocol, PDCP, packet data units, PDUs, which are intended to be delivered to the wireless device (1 10), each DL PDCP PDU having a PDCP sequence number, SN; and

- transmitting (S420) to the PDCP entity (152), in response to the received DL PDCP PDUs, information indicating one or more of the received DL PDCP PDUs which have been successfully, but not-in-sequence, delivered to the wireless device (1 10)

12. The method according to the claim 11 , wherein transmitting (S420) the information comprises: transmitting a Downlink Data Delivery Status, DDDS, frame.

13. The method according to any one of the claims 11-12, wherein the information comprises one or more PDCP SNs.

14. The method according to any one of the claims 11-13, wherein the information indicating one or more of the transmitted DL PDCP PDUs which have been successfully, but not-in-sequence, delivered to the wireless device (110) comprises one or more of:

- a flag indicating a presence of one or more blocks specifying DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device (1 10);

- a length field indicating how many blocks; or

for each block,

-a starting field indicating a start of the block; and

- a size field indicating a size of the block.

15. A computer program comprising instructions, which when executed by a processor, causes the processor to perform actions according to any of the claims 1 1-14.

16. A carrier comprising the computer program of claim 15, wherein the carrier is one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or a computer- readable storage medium.

17. A packet data convergence protocol, PDCP, entity (152) for providing multi connectivity to a wireless device in a wireless communication network, configured to:

18. The PDCP entity (152) according to the claim 17, wherein the PDCP entity (152) is configured to receive the information from at least one of the one or more RLC entities by: receiving at least one Downlink Data Delivery Status, DDDS, frame from at least one of the one or more RLC entities.

19. The PDCP entity (152) according to any one of the claims 17-18, wherein the information comprises one or more PDCP SNs.

20. The PDCP entity (152) according to any one of the claims 17-19, the PDCP entity (152) is further configured to:

- determine one or more DL PDCP PDUs which have been transmitted to the one or more RLC entities but not successfully delivered to the wireless device based on the information; and/or

21. The PDCP entity (152) according to the claim 20, wherein the different RLC entity is associated with a cell different from the one or more RLC entities.

22. The PDCP entity (152) according to any one of the claims 17-21 , wherein the information indicating one or more of the transmitted DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device comprises one or more of:

- a length field indicating how many blocks; or

for each block,

-a starting field indicating a start of the block; and

- a size field indicating a size of the block.

23. The PDCP entity (152) according to any one of the claims 17-22, when the PDCP entity (152) is configured to transmit the DL PDCP PDUs to more RLC entities, the PDCP entity (152) is further configured to duplicate the DL PDCP PDUs for each RLC entity and transmit one copy of the DL PDCP PDUs to each RLC entity.

24. The PDCP entity (152) according to the claim 23, wherein the duplicated DL PDCP PDUs have a same PDCP SN.

25. A radio link control, RLC, entity (154) which is associated with multi connectivity, configured to:

- receive downlink, DL, packet data convergence protocol, PDCP, packet data units, PDUs, which are intended to be delivered to a wireless device from a PDCP entity providing the multi connectivity to the wireless device in a wireless communication network, each DL PDCP PDU having a PDCP sequence number, SN; and

26. The RLC entity (154) according to the claim 25, wherein the RLC entity (154) is configured to transmit the information by: transmitting a Downlink Data Delivery Status, DDDS, frame.

27. The RLC entity (154) according to any one of the claims 25-26, wherein the

information comprises one or more PDCP SNs.

28. The RLC entity (154) according to any one of the claims 25-27, wherein the information indicating one or more of the transmitted DL PDCP PDUs which have been successfully but not-in-sequence delivered to the wireless device comprises one or more of:

- a length field indicating how many blocks; or

for each block,

-a starting field indicating a start of the block; and

- a size field indicating a size of the block.

29. A radio access node comprises at least one radio link control, RLC, entity (154) according to any one of the claims 25-28.