Patent Publication Number: US-2023147845-A1

Title: Preventing / mitigating packet loss in iab systems

Description:
TECHNICAL FIELD 
     This relates to mobile communications networks, and in particular to preventing or mitigating packet loss in Integrated Access Backhaul systems. 
     BACKGROUND 
     A mobile communication system supports Integrated Access Backhaul technology, in particular allowing a multi-hop path between a UE device and a “donor” node. In such a situation, there is a possibility that one link in the multi-hop path will fail. In some cases, the path will be switched. 
     In such situations, as discussed in more detail below, there is a danger that packets will be lost. 
     SUMMARY 
     According to a first aspect, there is provided a method performed by a wireless device for transmitting PDCP packets over a multi-hop path to a receiver, the method comprising:
         in response to receiving a PDCP status PDU indicating that at least one transmitted PDCP packet has not been received, retransmitting the at least one transmitted PDCP packet that has not been received, even if said transmitted PDCP packet has been acknowledged by a lower protocol layer.       

     The method may further comprise the step of discarding the transmitted PDCP packet in response to receiving a PDCP status PDU confirming that the packet has been received at the receiver. 
     According to a second aspect, there is provided a method performed by a wireless device for transmitting PDCP packets over a multi-hop path to a receiver, the method comprising:
         in response to receiving PDCP data recovery or PDCP re-establishment RRC signaling indicating that at least one transmitted PDCP packet has not been received, retransmitting the at least one transmitted PDCP packet that has not been received, even if said transmitted PDCP packet has been acknowledged by a lower protocol layer.       

     According to a third aspect, there is provided a method performed by a wireless device for transmitting PDCP packets over a multi-hop path to a receiver, the method comprising:
         in a RLC of the wireless device, when it is determined that PDCP PDUs have been successfully delivered, refraining from immediately indicating the successful delivery to a PDCP of the wireless device.       

     The method may comprise configuring indication of the successful delivery in response to at least one information element received in an RLC configuration. 
     The method may comprise not indicating to the PDCP layer the successful delivery of PDCP PDUs. 
     The method may comprise waiting for a configured delay period before indicating to the PDCP layer the successful delivery of PDCP PDUs. 
     The method may comprise indicating to the PDCP layer the successful delivery of PDCP PDUs only when a configured number of PDCP PDUs have been successfully delivered, and comprising specifying the PDUs that were successfully delivered. 
     According to a fourth aspect, there is provided a wireless device, comprising:
         transceiver circuitry, for communicating with at least one other network node, and   a processor, configured for performing a method in accordance with one of the first to third aspects.       

     According to a fifth aspect, there is provided a method performed by a network node, the method comprising:
         determining whether a wireless device is connecting to the network via an IAB node, and   if it is determined that the wireless device is not connecting to the network via an IAB node, configuring the wireless device with a first PDCP SDU discard timer, and   if it is determined that the wireless device is connecting to the network via an IAB node, configuring the wireless device with a second PDCP SDU discard timer that is longer than the first PDCP SDU discard timer.       

     The step of configuring the UE with a PDCP SDU discard timer may comprise configuring an individual bearer of the wireless device with a PDCP SDU discard timer. 
     The method may comprise determining a duration of the second PDCP SDU discard timer based on a delay tolerance of the individual bearer. 
     The method may comprise determining a duration of the second PDCP SDU discard timer based on a data rate of the individual bearer. 
     The method may comprise determining a duration of the second PDCP SDU discard timer based on a number of hops separating the wireless device from the network node. 
     According to a sixth aspect, there is provided a method performed by a network node, the method comprising:
         configuring a wireless device with a PDCP SDU discard timer, by including a corresponding information element in a PDCP configuration, wherein the PDCP SDU discard timer is such that the wireless device refrains from discarding a transmitted PDU until the SDU discard timer has expired, even if the transmitted PDU is acknowledged by a lower protocol layer.       

     The method may comprise configuring the wireless device with the PDCP SDU discard timer in response to determining that the wireless device is connecting to the network via an IAB node. 
     The method may comprise configuring the wireless device with the PDCP SDU discard timer based on a QoS requirement of the wireless device. 
     According to a seventh aspect, there is provided a method performed by a network node, the method comprising:
         configuring a RLC of a wireless device such that, when it is determined by the RLC that PDCP PDUs have been successfully delivered, the RLC refrains from immediately indicating the successful delivery to a PDCP of the wireless device.       

     The method may comprise configuring the RLC of the wireless device such that it does not indicate to the PDCP layer the successful delivery of PDCP PDUs. 
     The method may comprise configuring the RLC of the wireless device such that it waits for a configured delay period before indicating to the PDCP layer the successful delivery of PDCP PDUs. 
     The method may comprise configuring the RLC of the wireless device such that it indicates to the PDCP layer the successful delivery of PDCP PDUs only when a configured number of PDCP PDUs have been successfully delivered, and such that it specifies the PDUs that were successfully delivered. 
     The method may comprise configuring the RLC of the wireless device such that it refrains from immediately indicating the successful delivery to a PDCP of the wireless device, in response to determining that the wireless device is connecting via at least one relay or IAB node. 
     The method may further comprise, in response to determining that the wireless device is connecting via at least one relay or IAB node configuring the wireless device with an increased t-PollRetransmit value of the RLC, and comprising determining the t-PollRetransmit timer value based on how many hops away the UE is. 
     The method may further comprise, in response to determining that the wireless device is connecting via at least one relay or IAB node, configuring an increased t-StatusProhibit value of the RLC at a receiver node,
         wherein, for UL traffic, the receiver node is an RLC entity at the network corresponding to the respective bearer, and   comprising determining the t-StatusProhibit timer value based on how many hops away the UE is.       

     The method may further comprise, in response to determining that the wireless device is connecting via at least one relay or IAB node, configuring an increased maxRetrxThreshold value of the RLC of the wireless device, and comprising determining the maxRetrxThreshold value of the RLC of the wireless device based on how many hops away the UE is. 
     The method may further comprise, in response to determining that the wireless device is connecting via at least one relay or IAB node, sending RLC status PDUs, without being polled, so that the wireless device can delete already received PDUs from the retransmission buffer. 
     The method may comprise sending the RLC status PDUs only to indicate that a certain number of packets were received in sequence. 
     According to an eighth aspect, there is provided a network node, comprising:
         transceiver circuitry, for communicating with at least one other network node, and   a processor, configured for performing a method in accordance with one of the fifth to seventh aspects.       

     A number of embodiments are disclosed herein. 
     In Group A embodiments, there is provided a method performed by a wireless device for transmitting PDCP packets over a multi-hop path to a receiver, the method comprising:
         if a transmitted PDCP packet is acknowledged by a lower protocol layer, refraining from discarding the transmitted PDCP packet.       

     The method may further comprise the step of discarding the transmitted PDCP packet in response to receiving a PDCP status PDU confirming that the packet has been received at the receiver. 
     The method may further comprise the step of discarding the transmitted PDCP packet in response to expiry of a SDU discard timer. 
     The method may further comprise:
         in response to receiving a PDCP status PDU indicating that at least one transmitted PDCP packet has not been received, retransmitting the at least one transmitted PDCP packet that has not been received.       

     In that case, the method may comprise retransmitting the at least one transmitted PDCP packet immediately. 
     The method may comprise retransmitting the at least one transmitted PDCP packet, even if said transmitted PDCP packet has been acknowledged by a lower protocol layer. 
     The PDCP status PDU indicating that at least one transmitted PDCP packet has not been received may include a flag indicating that the at least one transmitted PDCP packet should be retransmitted immediately. 
     The method may further comprise:
         in response to receiving PDCP data recovery or PDCP re-establishment RRC signaling indicating that at least one transmitted PDCP packet has not been received, retransmitting the at least one transmitted PDCP packet that has not been received.       

     In that case, the method may comprise retransmitting the at least one transmitted PDCP packet, even if said transmitted PDCP packet has been acknowledged by a lower protocol layer. 
     The PDCP data recovery or PDCP re-establishment RRC signaling indicating that at least one transmitted PDCP packet has not been received may include an Information Element indicating that the at least one transmitted PDCP packet should be retransmitted. 
     In other Group A embodiments, there is provided a method performed by a wireless device for transmitting PDCP packets over a multi-hop path to a receiver, the method comprising:
         receiving configuration information from a network node defining a SDU discard timer value, and refraining from discarding a transmitted PDU until the SDU discard timer has expired, even if the transmitted PDU packet is acknowledged by a lower protocol layer.       

     The method may further comprise defining a queue management discard timer, after expiry of which a PDCP SDU that has been buffered, but not transmitted, will be discarded. 
     In other Group A embodiments, there is provided a method performed by a wireless device for transmitting PDCP packets over a multi-hop path to a receiver, the method comprising:
         defining a SDU discard timer value,   starting the SDU discard timer, and   refraining from discarding a transmitted PDU until the SDU discard timer has expired, even if the transmitted PDU is acknowledged by a lower protocol layer.       

     The method may comprise starting the SDU discard timer when a SDU arrives at the PDCP. 
     The method may comprise starting the SDU discard timer when a PDCP PDU corresponding to an SDU is transmitted. 
     In other Group A embodiments, there is provided a method of operation of a wireless device, the method comprising:
         configuring the wireless device with a PDCP SDU discard timer, in response to receiving a corresponding information element in a PDCP configuration received from a network node.       

     The method may further comprise:
         in response to receiving a PDCP status PDU indicating that at least one transmitted PDCP packet has not been received, immediately retransmitting the at least one transmitted PDCP packet that has not been received.       

     In other Group A embodiments, there is provided a method performed by a wireless device for transmitting PDCP packets over a multi-hop path to a receiver, the method comprising:
         in a RLC of the wireless device, when it is determined that PDCP PDUs have been successfully delivered, refraining from immediately indicating the successful delivery to a PDCP of the wireless device.       

     The method may comprise configuring indication of the successful delivery in response to at least one information element received in an RLC configuration. 
     The method may comprise not indicating to the PDCP layer the successful delivery of PDCP PDUs. 
     The method may comprise waiting for a configured delay period before indicating to the PDCP layer the successful delivery of PDCP PDUs. 
     The method may comprise indicating to the PDCP layer the successful delivery of PDCP PDUs only when a configured number of PDCP PDUs have been successfully delivered. 
     The method may comprise specifying the PDUs that were successfully delivered. 
     The method may comprise specifying the PDUs that were successfully delivered by using a bitmap. 
     The method may comprise indicating to the PDCP layer only once per indication period the successful delivery of any PDCP PDUs during that indication period. 
     The method of any of the Group A embodiments may further comprise:
         providing user data; and   forwarding the user data to a host computer via the transmission to the base station.       

     In Group B embodiments, there is provided a method performed by a network node, the method comprising:
         determining whether a wireless device is connecting to the network via an IAB node, and   if it is determined that the wireless device is not connecting to the network via an IAB node, configuring the wireless device with a first PDCP SDU discard timer, and if it is determined that the wireless device is connecting to the network via an IAB node, configuring the wireless device with a second PDCP SDU discard timer that is longer than the first PDCP SDU discard timer.       

     Configuring the UE with a PDCP SDU discard timer may comprise configuring an individual bearer of the wireless device with a PDCP SDU discard timer. 
     The method may comprise determining a duration of the second PDCP SDU discard timer based on a delay tolerance. 
     When an individual bearer of the wireless device is configured with a PDCP SDU discard timer, the method may comprise determining a duration of the second PDCP SDU discard timer based on a delay tolerance of the individual bearer. 
     The method may comprise determining a duration of the second PDCP SDU discard timer based on a data rate. 
     The method may comprise determining a duration of the second PDCP SDU discard timer based on a data rate of the individual bearer. 
     The method may comprise determining a duration of the second PDCP SDU discard timer based on a number of hops separating the wireless device from the network node. 
     In other Group B embodiments, there is provided a method performed by a network node, the method comprising:
         configuring a wireless device with a PDCP SDU discard timer, by including a corresponding information element in a PDCP configuration.       

     The PDCP SDU discard timer may be such that the wireless device refrains from discarding a transmitted PDU until the SDU discard timer has expired, even if the transmitted PDU is acknowledged by a lower protocol layer. 
     The method may comprise configuring the wireless device with the PDCP SDU discard timer in response to determining that the wireless device is connecting to the network via an IAB node. 
     The method may comprise configuring the wireless device with the PDCP SDU discard timer based on a QoS requirement of the wireless device. 
     In other Group B embodiments, there is provided a method performed by a network node, the method comprising:
         configuring a RLC of a wireless device such that, when it is determined by the RLC that PDCP PDUs have been successfully delivered, the RLC refrains from immediately indicating the successful delivery to a PDCP of the wireless device.       

     The method may comprise configuring indication of the successful delivery in at least one information element in an RLC configuration sent to the wireless device. 
     The method may comprise configuring the RLC of the wireless device such that it does not indicate to the PDCP layer the successful delivery of PDCP PDUs. 
     The method may comprise configuring the RLC of the wireless device such that it waits for a configured delay period before indicating to the PDCP layer the successful delivery of PDCP PDUs. 
     The method may comprise configuring the RLC of the wireless device such that it indicates to the PDCP layer the successful delivery of PDCP PDUs only when a configured number of PDCP PDUs have been successfully delivered. 
     The method may comprise configuring the RLC of the wireless device such that it specifies the PDUs that were successfully delivered. 
     The method may comprise configuring the RLC of the wireless device such that it specifies the PDUs that were successfully delivered by using a bitmap. 
     The method may comprise configuring the RLC of the wireless device such that it indicates to the PDCP layer only once per indication period the successful delivery of any PDCP PDUs during that indication period. 
     The method may comprise configuring the RLC of the wireless device such that it refrains from immediately indicating the successful delivery to a PDCP of the wireless device, in response to determining that the wireless device is connecting via at least one relay or IAB node. 
     The method may further comprise, in response to determining that the wireless device is connecting via at least one relay or IAB node configuring the wireless device with an increased t-PollRetransmit value of the RLC. 
     The method may comprise determining the t-PollRetransmit timer value based on how many hops away the UE is. 
     The method may further comprise, in response to determining that the wireless device is connecting via at least one relay or IAB node, configuring an increased t-StatusProhibit value of the RLC at a receiver node. 
     For UL traffic, the receiver node may be an RLC entity at the network corresponding to the respective bearer. 
     The method may comprise determining the t-StatusProhibit timer value based on how many hops away the UE is. 
     The method may further comprise, in response to determining that the wireless device is connecting via at least one relay or IAB node, configuring an increased maxRetrxThreshold value of the RLC of the wireless device. 
     The method may comprise determining the maxRetrxThreshold value of the RLC of the wireless device based on how many hops away the UE is. 
     The method may further comprise, in response to determining that the wireless device is connecting via at least one relay or IAB node, sending RLC status PDUs, without being polled, so that the wireless device can delete already received PDUs from the retransmission buffer. 
     The method may comprise sending the RLC status PDUs only to indicate that a certain number of packets were received in sequence. 
     The method of any of the Group B embodiments may further comprise:
         obtaining user data; and   forwarding the user data to a host computer or a wireless device.       

     In Group C embodiments, there is provided a wireless device for transmitting PDCP packets over a multi-hop path to a receiver, the wireless device comprising:
         processing circuitry configured to perform any of the steps of any of the Group A embodiments; and   power supply circuitry configured to supply power to the wireless device.       

     In other Group C embodiments, there is provided a network node for configuring a wireless device, the network node comprising:
         processing circuitry configured to perform any of the steps of any of the Group B embodiments;   power supply circuitry configured to supply power to the network node.       

     In other Group C embodiments, there is provided a user equipment (UE) for transmitting PDCP packets over a multi-hop path to a receiver, the UE comprising:
         an antenna configured to send and receive wireless signals;   radio front-end circuitry connected to the antenna and to processing circuitry, and configured to condition signals communicated between the antenna and the processing circuitry;   the processing circuitry being configured to perform any of the steps of any of the Group A embodiments;   an input interface connected to the processing circuitry and configured to allow input of information into the UE to be processed by the processing circuitry;   an output interface connected to the processing circuitry and configured to output information from the UE that has been processed by the processing circuitry; and   a battery connected to the processing circuitry and configured to supply power to the UE.       

     In another Group C embodiment, there is provided a communication system including a host computer comprising:
         processing circuitry configured to provide user data; and   a communication interface configured to forward the user data to a cellular network for transmission to a user equipment (UE),   wherein the cellular network comprises a network node having processing circuitry, the processing circuitry configured to perform any of the steps of any of the Group B embodiments.       

     The communication system of the previous embodiment may further include the base station. 
     The communication system of the previous 2 embodiments may further include the UE, wherein the UE is configured to communicate with the base station. 
     In the communication system of the previous 3 embodiments:
         the processing circuitry of the host computer may be configured to execute a host application, thereby providing the user data; and   the UE may comprise processing circuitry configured to execute a client application associated with the host application.       

     In another Group C embodiment, there is provided a method implemented in a communication system including a host computer, a base station and a user equipment (UE), the method comprising:
         at the host computer, providing user data; and   at the host computer, initiating a transmission carrying the user data to the UE via a cellular network comprising the base station, wherein the base station performs any of the steps of any of the Group B embodiments.       

     The method of the previous embodiment may further comprising, at the base station, transmitting the user data. 
     In the method of the previous 2 embodiments, the user data may be provided at the host computer by executing a host application, the method further comprising, at the UE, executing a client application associated with the host application. 
     In another Group C embodiment, there is provided a user equipment (UE) configured to communicate with a base station, the UE comprising a radio interface and processing circuitry configured to performs the of the previous 3 embodiments. 
     In another Group C embodiment, there is provided a communication system including a host computer comprising:
         processing circuitry configured to provide user data; and   a communication interface configured to forward user data to a cellular network for transmission to a user equipment (UE),   wherein the UE comprises a radio interface and processing circuitry, the UE&#39;s components configured to perform any of the steps of any of the Group A embodiments.       

     In the communication system of the previous embodiment, the cellular network may further include a base station configured to communicate with the UE. 
     In the communication system of the previous 2 embodiments:
         the processing circuitry of the host computer may be configured to execute a host application, thereby providing the user data; and   the UE&#39;s processing circuitry may be configured to execute a client application associated with the host application.       

     In another Group C embodiment, there is provided a method implemented in a communication system including a host computer, a base station and a user equipment (UE), the method comprising:
         at the host computer, providing user data; and   at the host computer, initiating a transmission carrying the user data to the UE via a cellular network comprising the base station, wherein the UE performs any of the steps of any of the Group A embodiments.       

     The method of the previous embodiment may further comprise at the UE, receiving the user data from the base station. 
     In another Group C embodiment, there is provided a communication system including a host computer comprising:
         communication interface configured to receive user data originating from a transmission from a user equipment (UE) to a base station,   wherein the UE comprises a radio interface and processing circuitry, the UE&#39;s processing circuitry configured to perform any of the steps of any of the Group A embodiments.       

     The communication system of the previous embodiment may further include the UE. 
     The communication system of the previous 2 embodiments may further include the base station, wherein the base station comprises a radio interface configured to communicate with the UE and a communication interface configured to forward to the host computer the user data carried by a transmission from the UE to the base station. 
     In the communication system of the previous 3 embodiments:
         the processing circuitry of the host computer may be configured to execute a host application; and   the UE&#39;s processing circuitry may be configured to execute a client application associated with the host application, thereby providing the user data.       

     In the communication system of the previous 4 embodiments:
         the processing circuitry of the host computer may be configured to execute a host application, thereby providing request data; and   the UE&#39;s processing circuitry may be configured to execute a client application associated with the host application, thereby providing the user data in response to the request data.       

     In another Group C embodiment, there is provided a method implemented in a communication system including a host computer, a base station and a user equipment (UE), the method comprising:
         at the host computer, receiving user data transmitted to the base station from the UE, wherein the UE performs any of the steps of any of the Group A embodiments.       

     The method of the previous embodiment may further comprise, at the UE, providing the user data to the base station. 
     The method of the previous 2 embodiments may further comprise:
         at the UE, executing a client application, thereby providing the user data to be transmitted; and   at the host computer, executing a host application associated with the client application.       

     The method of the previous 3 embodiments may further comprise:
         at the UE, executing a client application; and   at the UE, receiving input data to the client application, the input data being provided at the host computer by executing a host application associated with the client application,   wherein the user data to be transmitted is provided by the client application in response to the input data.       

     In another Group C embodiment, there is provided a communication system including a host computer comprising a communication interface configured to receive user data originating from a transmission from a user equipment (UE) to a base station, wherein the base station comprises a radio interface and processing circuitry, the base station&#39;s processing circuitry configured to perform any of the steps of any of the Group B embodiments. 
     The communication system of the previous embodiment may further include the base station. 
     The communication system of the previous 2 embodiments may further include the UE, wherein the UE is configured to communicate with the base station. 
     In the communication system of the previous 3 embodiments:
         the processing circuitry of the host computer may be configured to execute a host application;   the UE may be configured to execute a client application associated with the host application, thereby providing the user data to be received by the host computer.       

     In another Group C embodiment, there is provided a method implemented in a communication system including a host computer, a base station and a user equipment (UE), the method comprising:
         at the host computer, receiving, from the base station, user data originating from a transmission which the base station has received from the UE, wherein the UE performs any of the steps of any of the Group A embodiments.       

     The method of the previous embodiment may further comprise, at the base station, receiving the user data from the UE. 
     The method of the previous 2 embodiments may further comprise, at the base station, initiating a transmission of the received user data to the host computer. 
     There are, proposed herein, various embodiments which address one or more of the issues disclosed herein. Thus, certain embodiments may provide the technical advantage of providing methods for preventing or recovering from PDCP packet loss in a multi-hop system where hop by hop RLC ARQ is employed. Certain embodiments may allow loss of PDCP packets to be prevented or mitigated in a multi-hop IAB scenario utilizing hop by hop ARQ, without involving higher layers, thereby preventing increased latency and throughput degradation. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art. 
         FIG.  1    illustrates an architecture with separate Central Units and Distributed Units. 
         FIG.  2    illustrates an architecture with separation of the Central Unit Control Plane and User Plane. 
         FIG.  3    is a first reference diagram for an architecture as described herein. 
         FIG.  4    is a reference diagram for an architecture as described herein. 
         FIG.  5    illustrates examples of protocol stacks for UE access. 
         FIG.  6    illustrates examples of protocol stacks for UE access. 
         FIG.  7    illustrates an example of an alternative protocol stack. 
         FIG.  8    illustrates an example of an alternative protocol stack. 
         FIG.  9    illustrates an example of an alternative protocol stack. 
         FIG.  10    illustrates an example of an alternative protocol stack. 
         FIG.  11    is a protocol stack diagram for an example of a multi-hop scenario. 
         FIG.  12    is a flow chart illustrating a method in accordance with some embodiments. 
         FIG.  13    is a flow chart illustrating a method in accordance with some embodiments. 
         FIG.  14    illustrates a wireless network in accordance with some embodiments. 
         FIG.  15    illustrates a User Equipment in accordance with some embodiments. 
         FIG.  16    illustrates a virtualization environment in accordance with some embodiments. 
         FIG.  17    illustrates a telecommunication network connected via an intermediate network to a host computer in accordance with some embodiments. 
         FIG.  18    illustrates a host computer communicating via a base station with a user equipment over a partially wireless connection in accordance with some embodiments. 
         FIG.  19    is a flow chart illustrating a method implemented in a communication system including a host computer, a base station and a user equipment in accordance with some embodiments. 
         FIG.  20    is a flow chart illustrating a method implemented in a communication system including a host computer, a base station and a user equipment in accordance with some embodiments. 
         FIG.  21    is a flow chart illustrating a method implemented in a communication system including a host computer, a base station and a user equipment in accordance with some embodiments. 
         FIG.  22    is a flow chart illustrating a method implemented in a communication system including a host computer, a base station and a user equipment in accordance with some embodiments. 
         FIG.  23    illustrates a virtualization apparatus in accordance with some embodiments, 
         FIG.  24    illustrates a virtualization apparatus in accordance with some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     Some of the embodiments contemplated herein will now be described more fully with reference to the accompanying drawings. Other embodiments, however, are contained within the scope of the subject matter disclosed herein, the disclosed subject matter should not be construed as limited to only the embodiments set forth herein; rather, these embodiments are provided by way of example to convey the scope of the subject matter to those skilled in the art. 
     Generally, all terms used herein are to be interpreted according to their ordinary meaning in the relevant technical field, unless a different meaning is clearly given and/or is implied from the context in which it is used. All references to a/an/the element, apparatus, component, means, step, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any methods disclosed herein do not have to be performed in the exact order disclosed, unless a step is explicitly described as following or preceding another step and/or where it is implicit that a step must follow or precede another step. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features and advantages of the enclosed embodiments will be apparent from the following description. 
     Initially, this section provides a background of the following areas:
         gNB-CU/DU split in NR and NG-RAN. This is relevant to the disclosure in that the CU/DU split is reused for IAB nodes (Relays) in that the IAB node terminates DU functionality and connects to CU which is located in the “fixed” part of the network e.g. on the opposite side of the wireless backhaul interface.   Overview of the status of Integrated Access and Backhaul (IAB) in 3GPP.   Overview of different architectures in IAB.
 
gNB-CU/DU Split in NR and NG-RAN
       

     In New Radio (NR) and for the Next Generation (NG) Radio Access Network (RAN), it has been agreed, as shown in  FIG.  1   , to support a separation for the base station (gNB)  102  into a Central Unit (CU)  104  and one or more Distributed Unit (DU)  106 . The DU  106  terminates the radio interface towards the UE including the Radio Link Control (RLC), Medium Access Control (MAC) and Physical layer protocols, while the CU  104  terminates the Packet Data Convergence Protocol (PDCP) and Radio Resource Control (RRC) protocols towards the User Equipment (UE) as well as the NG-Control Plane (C) and User Plane (U) interfaces towards the 5G Core network (5GC)  108  and Xn/X2 interface towards other NR gNBs and Long Term Evolution (LTE) base stations (eNBs). The CU/DU separation is described further in 3GPP TS 38.401. Between the CU and DU an F1 interface is defined. The F1 application part protocol (F1-AP) is defined in 3GPP 38.473. 
     Additionally, as shown in  FIG.  2   , it has been agreed in 3GPP RAN3 WG to support a separation of the gNB-CU into a CU-CP function  202  (incl. RRC and PDCP for signaling radio bearers) and CU-UP function  204  (incl. PDCP for user plane). The CU-CP and CU-UP parts communicate with each other using the E1 interface and the E1-AP protocol. 
     Integrated Access Backhaul 
     Densification via the deployment of more and more base stations (whether macro or micro base stations) is one of the mechanisms that can be employed to satisfy the ever increasing demand for more and more bandwidth/capacity in mobile networks (mainly driven by the high adoption of video streaming services). Due to the availability of more spectrum in the millimeter wave (mmw) band, deploying small cells that operate in this band is an attractive deployment option for these purposes. However, deploying fiber to the small cells, which is the usual way in which small cells are deployed, can end up being very expensive and impractical. Thus, employing a wireless link for connecting the small cells to the operator&#39;s network is a cheaper and practical alternative. One such solution is an integrated access backhaul (IAB) network where the operator can utilize part of the radio resources for the backhaul link. 
     Integrated access and backhaul has been studied earlier in 3GPP in the scope of LTE Rel-10. In that work, an architecture was adopted where a Relay Node (RN) has the functionality of an LTE eNB and UE modem. The RN is connected to a donor eNB which has a S1/X2 proxy functionality hiding the RN from the rest of the network. That architecture enabled the Donor eNB to also be aware of the UEs behind the RN and hide any UE mobility between Donor eNB and Relay Node (2) on the same Donor eNB from the CN. 
     During the Rel-10 also other architectures were considered e.g. where the RNs are more transparent to the Donor gNB and allocated a separate stand-alone P/S-GW node. 
     For NR, similar architecture options can also be considered. One potential difference compared to LTE (besides lower layer differences) is that a gNB-CU/DU (Centralized Unit/Distributed Unit) split is defined for NR which allows a separation of time critical RLC/MAC/PHY protocols from less time critical RRC/PDCP protocols. Such a split could also be applied for the integrated access and backhaul case. Other differences anticipated in NR as compared to LTE with regards to IAB is the support of multiple hops as well as the support of redundant paths. 
     Integrated Access Backhaul Architectures 
     Currently in 3GPP the following architectures for supporting user plane traffic over IAB node have been captured in 3GPP TS 38.874 (version 0.2.1). 
     Architecture 1a leverages CU/DU-split architecture.  FIG.  3    shows the reference diagram for a two-hop chain of IAB-nodes underneath an IAB-donor. 
     In this architecture, each IAB node  302  holds a DU  304  and an MT  306 . Via the MT  306 , the IAB-node  302  connects to an upstream IAB-node  302  or the IAB-donor  308 . Via the DU, the IAB-node  302  establishes RLC-channels to UEs  310  and to MTs  306  of downstream IAB-nodes  302 . For MTs, this RLC-channel may refer to a modified RLC*. Whether an IAB node can connect to more than one upstream IAB-node or IAB-donor is FFS. 
     The donor  308  also holds a DU  312  to support UEs and MTs of downstream IAB-nodes. The IAB-donor holds a CU  314  for the DUs  304  of all IAB-nodes  302  and for its own DU  312 . It is FFS if different CUs can serve the DUs of the IAB-nodes. Each DU on an IAB-node connects to the CU in the IAB-donor using a modified form of F1, which is referred to as F1*. F1*-U runs over RLC channels on the wireless backhaul between the MT on the serving IAB-node and the DU on the donor. F1*-U transport between MT and DU on the serving IAB-node as well as between DU and CU on the donor is FFS. An adaptation layer is added, which holds routing information, enabling hop-by-hop forwarding. It replaces the IP functionality of the standard F1-stack. F1*-U may carry a GTP-U header for the end-to-end association between CU and DU. In a further enhancement, information carried inside the GTP-U header may be included into the adaption layer. Further, optimizations to RLC may be considered such as applying ARQ only on the end-to-end connection opposed to hop-by-hop. The right side of  FIG.  3    shows two examples of such F1*-U protocol stacks. In this figure, enhancements of RLC are referred to as RLC*. The MT of each IAB-node further sustains NAS connectivity to the NGC, e.g., for authentication of the IAB-node. It further sustains a PDU-session via the NGC, e.g., to provide the IAB-node with connectivity to the OAM. 
     Details of F1*, the adaptation layer and RLC* remain to be studied. Details of hop-by-hop forwarding are FFS. Transport of F1-AP is FFS. Protocol translation between F1* and F1 in case the IAB-donor is split is FFS. 
     Architecture 1 b also leverages CU/DU-split architecture.  FIG.  4    shows the reference diagram for a two-hop chain of IAB-nodes underneath an IAB-donor. Note that the IAB-donor only holds one logical CU. Whether an IAB node can connect to more than one upstream IAB-node or IAB-donor is FFS. 
     In this architecture, each IAB-node  402  and the IAB-donor  404  hold the same functions as in architecture 1 a. Also, as in architecture 1 a, every backhaul link establishes an RLC-channel, and an adaptation layer is inserted to enable hop-by-hop forwarding of F1*. 
     Opposed to architecture 1 a, the MT  406  on each IAB-node  402  establishes a PDU-session with a User Plane Function (UPF) residing on the donor  404 . The MT&#39;s PDU-session carries F1* for the collocated DU  410 . In this manner, the PDU-session provides a point-to-point link between CU  412  and DU  410 . On intermediate hops, the PDCP-PDUs of F1* are forwarded via adaptation layer in the same manner as described for architecture 1 a. The right side of  FIG.  4    shows an example of the F1*-U protocol stack. 
     User-Plane Considerations for Architecture Group 1 
     General 
     The following subsections describe various user plane aspects for architecture group 1 including placement of an adaptation layer, functions supported by the adaptation layer, support of multi-hop RLC, impacts on scheduler and QoS. The study will analyse the described architecture options to identify trade-offs between these various aspects with the goal to recommend a single architecture for this group. 
     Adaptation Layer 
     The UE establishes RLC channels to the DU on the UE&#39;s access IAB node in compliance with TS 38.300. Each of these RLC-channels is extended via a potentially modified form of F1-U, referred to as F1*-U, between the UE&#39;s access DU and the IAB donor. 
     The information embedded in F1*-U is carried over RLC-channels across the backhaul links. 
     Transport of F1*-U over the wireless backhaul is enabled by an adaptation layer, which is integrated with the RLC channel. Within the IAB-donor (referred to as fronthaul), the baseline is to use native F1-U stack (see section 9). The IAB-donor DU relays between F1-U on the fronthaul and F1*-U on the wireless backhaul. 
       FIG.  5    shows examples of protocol stacks for UE-access using L2-relaying with an adaptation layer for architecture 1a described above.  FIG.  6    shows examples of protocol stacks for UE-access using L2-relaying with adaptation layer for architecture 1b described above.  FIGS.  5  and  6    show example protocol stacks and do not preclude other possibilities. While RLC channels serving for backhauling include the adaptation layer, it is FSS if the adaptation layer is also included in IAB-node access links (adapt is dashed in  FIG.  6   ). 
     In architecture 1 a, information carried on the adaptation layer supports the following functions:
         Identification of the UE-bearer for the PDU,   Routing across the wireless backhaul topology,   QoS-enforcement by the scheduler on DL and UL on the wireless backhaul link,   Mapping of UE user-plane PDUs to backhaul RLC channels,   Others.       

     In architecture 1 b, information carried on the adaptation layer supports the following functions:
         Routing across the wireless backhaul topology,   QoS-enforcement by the scheduler on DL and UL on the wireless backhaul link,   Mapping of UE user-plane PDUs to backhaul RLC channels   Others.       

     Content Carried on the Adaptation Layer Header 
     The study will identify all information to be carried on the adaptation layer header. This may include:
         UE-bearer-specific Id   UE-specific Id   Route Id, IAB-node or IAB-donor address   QoS information   Potentially other information       

     Details of the information carried in the adaptation layer are FFS. 
     Processing of Adaptation Layer Information 
     
         
         
           
             The study will identify which of the information on the adaptation layer is processed to support the above functions on each on-path IAB-node (hop-by-hop), 
             and/or on the UE&#39;s access-IAB-node and the IAB-donor (end-to-end).
 
Integration of Adaptation Layer into L2 Stack
 
           
         
       
    
     The following options are available for adaptation layer placements:
         integrated with MAC layer or above MAC layer (examples shown in  FIG.  5   a    and  FIG.  5   b   ),   above RLC layer (examples shown in  FIG.  5   d   ,  FIG.  5   e    and  FIG.  6   ).       

     Adaptation Header Structure 
     The adaptation layer may consist of sublayers. It is conceivable, for example, that the GTP-U header becomes a part of the adaptation layer. It is also possible that the GTP-U header is carried on top of the adaptation layer to carry end-to-end association between the IAB-node DU and the CU (example is shown in  FIG.  5   d   ). 
     Alternatively, an IP header may be part of the adaptation layer or carried on top of the adaptation layer. One example is shown in  FIG.  5   e   . In this example, the IAB-donor DU holds an IP routing function to extend the IP-routing plane of the fronthaul to the IP-layer carried by adapt on the wireless backhaul. This allows native F1-U to be established end-to-end, i.e. between IAB-node DUs and IAB-donor CU-UP. The scenario implies that each IAB-node holds an IP-address, which is routable from the fronthaul via the IAB-donor DU. The IAB-nodes&#39; IP addresses may further be used for routing on the wireless backhaul. 
     Note that the IP-layer on top of Adapt does not represent a Protocol Data Unit (PDU) session. The MT&#39;s first hop router on this IP-layer therefore does not have to hold a UPF. 
     The design of the adaption header is FFS. 
     Observations on Adaptation Layer Placement 
     1. The above-RLC adaptation layer can only support hop-by-hop ARQ. The above-MAC adaptation layer can support both hop-by-hop and end-to-end ARQ.
 
2. Both adaptation layer placements can support aggregated routing, e.g. by inserting an IAB-node address into the adaptation header.
 
3. Both adaptation layer placements can support per-UE-bearer QoS for a large number of UE-bearers.
 
a. For above-RLC adaptation layer, the LCID space has to be enhanced since each UE-bearer is mapped to an independent logical channel.
 
b. For above-MAC adaptation layer, UE-bearer-related info has to be carried on the adaptation header.
 
4. Both adaptation layer placements can support aggregated QoS handling e.g. by inserting an aggregated QoS Id into the adaptation header.
 
a. Aggregated QoS handling reduces the number of queues. This is independent on where the adaptation layer is placed.
 
5. For both adaptation layer placements, aggregation of routing and QoS handling allows proactive configuration of intermediate on-path IAB-nodes, i.e. configuration is independent of UE-bearer establishment/release.
 
6. For both adaptation layer placements, RLC ARQ can be pre-processed on TX side.
 
     Multi-Hop RLC ARQ 
     For RLC AM, ARQ can be conducted hop-by-hop along access and backhaul links ( FIG.  5   c   ,  FIG.  5   d   ,  FIG.  5   e    and  FIG.  6   ). It is also possible to support ARQ end-to-end between UE and IAB-donor ( FIG.  5   a    and  FIG.  5   b   ). Since RLC segmentation is a just-in-time process, it is always conducted in a hop-by-hop manner.  FIGS.  5  and  6    show example protocol stacks and do not preclude other possibilities. 
     The type of multi-hop RLC ARQ and adaptation-layer placement have the following interdependence:
         End-to-end ARQ: Adaptation layer is integrated with MAC layer or placed above MAC layer   Hop-by-hop ARQ: No interdependence       

     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 illustrates some considerations for end-to-end and hop-by-hop ARQ: 
               
               
                 hop by hop vs. end to end RLC ARQ 
               
            
           
           
               
               
               
            
               
                 Metric 
                 Hop-by-hop RLC ARQ 
                 End-to-end RLC ARQ 
               
               
                   
               
               
                 Forwarding latency 
                 Potentially higher as packets have 
                 Potentially lower as packets do not 
               
               
                   
                 to pass through RLC-state machine 
                 go through the RLC state machine 
               
               
                   
                 on each hop. 
                 on intermediate IAB-nodes. 
               
               
                 Latency due to 
                 Independent of number of hops 
                 Increases with number of hops 
               
               
                 retransmission 
                   
                   
               
               
                 Capacity 
                 Packet loss requires 
                 Packet loss may imply 
               
               
                   
                 retransmission only on one link. 
                 retransmission on multiple links, 
               
               
                   
                 Avoids redundant retransmission of 
                 including those where the packet 
               
               
                   
                 packets over links where the 
                 was already successfully 
               
               
                   
                 packet has already been 
                 transmitted. 
               
               
                   
                 successfully transmitted. 
                   
               
               
                 Hop count limitation 
                 Hop count is not affected by max 
                 Hop count may be limited by the 
               
               
                 due to RLC 
                 window size. 
                 end-to-end RLC latency due to 
               
               
                 parameters 
                   
                 max window size. 
               
               
                 Hop count limitation 
                 Hop count may be limited by 
                 Hop count does not impact 
               
               
                 due to PCDP 
                 increasing disorder of PDCP PDUs 
                 disorder of PDCP PDUs due to 
               
               
                 parameters 
                 over sequential RLC ARQ hops. 
                 RLC ARQ. 
               
               
                   
                 This may increase probability to 
                   
               
               
                   
                 exceed max PDCP window size. 
                   
               
               
                 Processing and 
                 Larger since processing and 
                 Smaller since intermediate path- 
               
               
                 memory impact on 
                 memory is required on intermediate 
                 nodes do not need ARQ state 
               
               
                 intermediate IAB- 
                 IAB-nodes. 
                 machine and flow window. 
               
               
                 nodes 
                   
                   
               
               
                 RLC specification 
                 No stage-3 impact expected 
                 Potential stage-3 impact 
               
               
                 impact 
                   
                   
               
               
                 Operational impact 
                 IAB-nodes and IAB-donors use the 
                 End-to-end RLC ARQ results in a 
               
               
                 for IAB-node to IAB- 
                 same hop-by-hop RLC ARQ. As a 
                 greater architectural difference 
               
               
                 donor upgrades 
                 result, this functionality is 
                 between IAB nodes vs. IAB donor 
               
               
                   
                 completely unaffected by the 
                 nodes. As a result, additional effort 
               
               
                   
                 upgrade of IAB-node to IAB-donor 
                 may be required to complete an 
               
               
                   
                 at availability of fiber, potentially 
                 upgrade of an IAB node to an IAB 
               
               
                   
                 reducing the effort required to 
                 donor upon availability of fiber. 
               
               
                   
                 confirm proper operation. 
                   
               
               
                 Configuration 
                 RLC timers are not dependent on 
                 RLC timers become hop-count 
               
               
                 complexity 
                 hop-count. 
                 dependent. 
               
               
                   
               
            
           
         
       
     
     Control-Plane Considerations for Architecture Group 1 
     In architecture 1 a, the UE&#39;s and the MT&#39;s UP and RRC traffic can be protected via PDCP over the wireless backhaul. A mechanism has to be defined to also protect F1-AP traffic over the wireless backhaul. 
     The following three alternatives can be considered, although other alternatives are not precluded. 
       FIG.  7    shows protocol stacks for UE&#39;s RRC, MT&#39;s RRC and DU&#39;s F1-AP for a first alternative. In these examples, the adaptation layer is placed on top of RLC. On the IAB-node&#39;s access link, the adaptation layer may or may not be included. The example does not preclude other options. This alternative has the following main features:
         The UE&#39;s and the MT&#39;s RRC are carried over SRB.   On the UE&#39;s or MT&#39;s access link, the SRB uses an RLC-channel.   On the wireless backhaul links, the SRB&#39;s PDCP layer is carried over RLC-channels with adaptation layer. The adaptation layer placement in the RLC channel is the same for C-plane as for U-plane. The information carried on the adaptation layer may be different for SRB than for DRB.   The DU&#39;s F1-AP is encapsulated in RRC of the collocated MT. F1-AP is therefore protected by the PDCP of the underlying SRB.   Within the IAB-donor, the baseline is to use native F1-C stack (discussed below).       

       FIG.  8    shows protocol stacks for UE&#39;s RRC, MT&#39;s RRC and DU&#39;s F1-AP for a second alternative. In these examples, the adaptation layer resides on top of RLC. On the IAB-node&#39;s access link, the adaptation layer may or may not be included. The example does not preclude other options. This alternative has the following main features:
         The UE&#39;s and the MT&#39;s RRC are carried over SRB.   On the UE&#39;s or MT&#39;s access link, the SRB uses an RLC-channel.   On the wireless backhaul link, the PDCP of the RRC&#39;s SRB is encapsulated into F1-AP.   The DU&#39;s F1-AP is carried over an SRB of the collocated MT. F1-AP is protected by this SRB&#39;s PDCP.   On the wireless backhaul links, the PDCP of the F1-AP&#39;s SRB is carried over RLC-channels with adaptation layer. The adaptation layer placement in the RLC channel is the same for C-plane as for U-plane. The information carried on the adaptation layer may be different for SRB than for DRB.   Within the IAB-donor, the baseline is to use native F1-C stack (discussed below)       

       FIG.  9    shows protocol stacks for UE&#39;s RRC, MT&#39;s RRC and DU&#39;s F1-AP for a third alternative. In these examples, the adaptation layer resides on top of RLC. On the IAB-node&#39;s access link, the adaptation layer may or may not be included. The example does not preclude other options. This alternative has the following main features:
         The UE&#39;s and the MT&#39;s RRC are carried over SRB.   On the UE&#39;s or MT&#39;s access link, the RRC&#39;s SRB uses an RLC-channel. On the wireless backhaul links, the SRB&#39;s PDCP layer is carried over RLC-channels with adaptation layer. The adaptation layer placement in the RLC channel is the same for C-plane as for U-plane. The information carried on the adaptation layer may be different for SRB than for DRB.   The DU&#39;s F1-AP is also carried over an SRB of the collocated MT. F1-AP is protected by this SRB&#39;s PDCP.   On the wireless backhaul links, the PDCP of the SRB is also carried over RLC-channels with adaptation layer.   Within the IAB-donor, the baseline is to use native F1-C stack (discussed below).       

       FIG.  10    shows protocol stacks for UE&#39;s RRC, MT&#39;s RRC and DU&#39;s F1-AP for a fourth alternative. In these examples, the adaptation layer resides on top of RLC and carries an IP-layer as discussed in section 8.2.2. This alternative has the following main features:
         The IP-layer carried by adapt is connected to the fronthaul&#39;s IP-plane through a routing function at the IAB-donor DU. On this IP-layer, all IAB-nodes hold IP-addresses, which are routable from the IAB-donor CU-CP.   The extended IP-plane allows native F1-C to be used between IAB-node DU and IAB-donor CU-DP. Signalling traffic can be prioritized on this IP routing plane using DSCP markings in compliance with TS 38.474.   F1-C is protected via NDS, e.g. via D-TLS, as established by S3-181838.   The UE&#39;s and the MT&#39;s RRC use SRB, which is carried over F1-C in compliance with TS 38.470.       

     There currently exist certain challenges. 
     As discussed above, the adaptation layer for IAB can be either below or above RLC, and RLC ARQ can be performed hop by hop or end to end (i.e. between the donor DU and the IAB node). Performing the RLC ARQ hop by hop has several advantages as compared to end to end ARQ, as captured in Table 1. 
     However, there is one issue with the hop by hop ARQ that is not addressed above. Consider the example scenario shown in  FIG.  11   , where we have three hops, i.e. three intermediate IAB-nodes ( 1102 =IAB 3 ,  1104 =IAB 2 ,  1106 =IAB 1 ) between a UE  1108  and an IAB donor  1110 . Note that in this figure we are focusing on the adaptation layer placement and the RLC ARQ and not the whole end to end protocol stack, and thus some details of the protocols at the CU and IAB node are ignored. Thus, this figure is applicable to the protocol stacks of  FIGS.  5     c,d,e.    
     Assume there is a problem on one hop (for example a radio link failure), and that hop is redirected via another IAB node (for example, the link between IAB 2  and IAB 3  fails, and now the UE is connected via UE←→IAB 3 ←→IAB 4 ←→IAB 1 ←→IAB-donor). If the UE has deleted the PDCP packet already when it gets an ACK from RLC (which in the hop by hop case only cares about the transmission over the UE-IAB 3  link), then there may be no way to retransmit the lost packet (on the IAB 3  to IAB 2  link that has failed), while if it was an end to end ARQ, there will be a retransmission timeout at the UE&#39;s RLC and the packet will be retransmitted. 
     In the PDCP specs (38.323), section 5.3, regarding when the UE discards the PDCP Service Data Unit (SDU), it is written that: 
     “When the discardTimer expires for a PDCP SDU, or the successful delivery of a PDCP SDU is confirmed by PDCP status report, the transmitting PDCP entity shall discard the PDCP SDU along with the corresponding PDCP Data PDU. If the corresponding PDCP Data PDU has already been submitted to lower layers, the discard is indicated to lower layers. 
     “For SRBs, when upper layers request a PDCP SDU discard, the PDCP entity shall discard all stored PDCP SDUs and PDCP PDUs. 
     “NOTE: Discarding a PDCP SDU already associated with a PDCP SN causes a SN gap in the transmitted PDCP Data PDUs, which increases PDCP reordering delay in the receiving PDCP entity. It is up to UE implementation how to minimize SN gap after SDU discard” 
     Thus, the PDCP specification doesn&#39;t mandate the deletion of the PDCP packet based on RLC ACKs. 
     However, even if it is not explicitly specified that UE has to discard packets when ACK is indicated from lower layer, it is implicitly specified, because when PDCP should retransmit, due to PDCP recovery or re-establishment, only not yet ACKed PDUs are retransmitted. 
     NR PDCP Reestablishment: 
     
         
         
           
             for AM DRBs, from the first PDCP SDU for which the successful delivery of the corresponding PDCP Data PDU has not been confirmed by lower layers, perform retransmission or transmission of all the PDCP SDUs already associated with PDCP SNs in ascending order of the COUNT values associated to the PDCP SDU prior to the PDCP entity re-establishment as specified below:
           perform header compression of the PDCP SDU as specified in the subclause 5.7.4;   perform integrity protection and ciphering of the PDCP SDU using the COUNT value associated with this PDCP SDU as specified in the subclause 5.9 and 5.8;   submit the resulting PDCP Data PDU to lower layer.   
         
           
         
       
    
     NR PDCP Data Recovery 
     
         
         
           
             perform retransmission of all the PDCP Data PDUs previously submitted to re-established or released AM RLC entity in ascending order of the associated COUNT values from the first PDCP Data PDU for which the successful delivery has not been confirmed by lower layers. 
           
         
       
    
     Thus, according to current PDCP specifications, in case where a path switch is done in one of the intermediate hops in an IAB system (or we have a temporary RLF), PDCP packet losses could be incurred, and the packets have to be retransmitted at the higher layer (e.g. TCP) end-2-end, which could cause service performance degradation (high latency, throughput degradation because TCP may be forced to perform congestion avoidance or even slow start, etc. . . . ). 
     Certain aspects of the following disclosure and the associated embodiments may provide solutions to these or other challenges. The solution introduces methods for preventing or recovering from PDCP packet loss in a multi-hop system where hop by hop RLC ARQ is employed. Some of the embodiments require PDCP enhancements, while the others require RLC enhancements. 
     With the methods proposed herein, loss of PDCP packets can be prevented or mitigated in a multi-hop IAB scenario utilizing hop by hop ARQ, without involving higher layers, thereby preventing increased latency and throughput degradation. 
     Notes: 
     
         
         
           
             In the embodiments below, the text includes the phrases “the PDCP of the UE is configured with . . . ” or the “RLC of the UE is configured with . . . ”. It should be noted that by this we mean, the PDCP or the RLC of the UE bearers. This could be for all the bearers or a selected subset of bearers (depending on the QoS requirements of the bearers). 
             The embodiments below are written from UL traffic point of view. However, most of the embodiments are equally applicable for DL traffic. 
             The text below does not differentiate considerations for UP and CP (i.e. RRC) traffic. However, the network may decide to treat the configuration of the PDCP/RLC parameter for UP and CP differently, even for the same UE, as they have different QoS/priority requirements. 
             It should be noted that the network is aware of the path change that happens over the intermediate nodes (and it will probably be the donor CU/DU that sets up the new path, though autonomous path switch by intermediate nodes is not precluded, but in this case we assume the donor CU/DU will be informed about it). When the donor CU/DU becomes aware of the path change or initiates the path change, it can trigger the needed procedure (e.g. sending status PDUs, triggering PDCP recovery, etc. . . . ). In the descriptions below, we have focused on how these procedures have to be enhanced for the case of IAB and have not discussed on how the network discovers the path has changed. 
           
         
       
    
     EMBODIMENTS RELATED TO PDCP 
     Embodiment 1: The UE refrains from discarding PDCP packets even if they are ACKed by lower layers (i.e. it discards them only when the SDU discard timer expires or a PDCP status PDU is received that confirms the SDU has been received at the receiver). 
     Embodiment 1 a: A method according to embodiment 1, where upon receiving a PDCP status PDU that indicates some missing packets, the PDCP immediately retransmits these missing packets, even if the RLC has earlier indicated the packets have been ACKed. 
     According to embodiment 1 a, the PDCP status PDU receive operation thus becomes: 
     5.4.2 Receive Operation 
     
         
         
           
             For AM DRBs, when a PDCP status report is received in the downlink, the transmitting PDCP entity shall: 
             consider for each PDCP SDU, if any, with the bit in the bitmap set to ‘1’, or with the associated COUNT value less than the value of FMC field as successfully delivered, and discard the PDCP SDU as specified in the subclause 5.3. 
             perform retransmission of all the PDCP Data PDUs previously submitted to lower layers in ascending order of the associated COUNT values from the first PDCP Data PDU. 
           
         
       
    
     Embodiment 1 b: A method according to embodiment 1, where upon receiving a PDCP status PDU that indicates some missing packets, a new flag is also included in the status PDU (e.g. fastRetrans), which indicates to the PDCP to immediately retransmit these missing packets, even if the RLC has earlier indicated the packets have been ACKed. 
     According to embodiment 1 b, the PDCP status PDU receive operation thus becomes: 
     5.4.2 Receive Operation 
     
         
         
           
             For AM DRBs, when a PDCP status report is received in the downlink, the transmitting PDCP entity shall: 
             consider for each PDCP SDU, if any, with the bit in the bitmap set to ‘1’, or with the associated COUNT value less than the value of FMC field as successfully delivered, and discard the PDCP SDU as specified in the subclause 5.3. 
             if fastRetrans is included in the status report: 
             perform retransmission of all the PDCP Data PDUs previously submitted to lower layers in ascending order of the associated COUNT values from the first PDCP Data PDU. 
           
         
       
    
     Note that, in normal PDCP operation, the status report does not trigger retransmissions, and PDCP retransmission is only triggered via PDCP recovery or PDCP re-establishment, which have to be signaled to the UE via RRC. This is a slow process as compared to just sending a PDCU status PDU, especially if there is a CU-UP/CU-CP split, because there may be a need to communicate between the CU-UP and the CU-CP in order to ensure both the status PDU and the RRC message (e.g. triggering PDCP recovery) are sent to the UE. 
     Embodiment 1c: A method according to embodiment 1, where upon receiving an indication to perform a PDU recovery or re-establishment from higher layers (RRC), the PDCP will retransmit the packets that have been indicated to be missing, even if the RLC has earlier indicated those packets have been ACKed. 
     According to embodiment 1c, the PDCP recovery and re-establishment procedures become: 
     5.5 Data Recovery 
     
         
         
           
             For AM DRBs, when upper layers request a PDCP data recovery for a radio bearer, the transmitting PDCP entity shall: 
             perform retransmission of all the PDCP Data PDUs previously submitted to re-established or released AM RLC entity in ascending order of the associated COUNT values for which the successful delivery has not been confirmed by lower layers. 
           
         
       
    
     After performing the above procedures, the transmitting PDCP entity shall follow the procedures in subclause 5.2 
     Note: it should be noted that the RLC does not need to be re-established or released to perform the recovery in the case of IAB operation. 
     5.1.2 PDCP Entity Re-Establishment 
     When upper layers request a PDCP entity re-establishment, the UE shall additionally perform once the procedures described in this section. After performing the procedures in this section, the UE shall follow the procedures in subclause 5.2. 
     When upper layers request a PDCP entity re-establishment, the transmitting PDCP entity shall:
         for UM DRBs and AM DRBs, reset the header compression protocol for uplink and start with an IR state in U-mode (as defined in RFC 3095 [8] and RFC 4815 [9]) if drb-ContinueROHC is not configured in TS 38.331 [3];   for UM DRBs and SRBs, set TX_NEXT to the initial value;   for SRBs, discard all stored PDCP SDUs and PDCP PDUs;   apply the ciphering algorithm and key provided by upper layers during the PDCP entity re-establishment procedure;   apply the integrity protection algorithm and key provided by upper layers during the PDCP entity re-establishment procedure;   for UM DRBs, for each PDCP SDU already associated with a PDCP SN but for which a corresponding PDU has not previously been submitted to lower layers:   consider the PDCP SDUs as received from upper layer;   perform transmission of the PDCP SDUs in ascending order of the COUNT value associated to the PDCP SDU prior to the PDCP re-establishment without restarting the discardTimer;   for AM DRBs, from the first PDCP SDU for which the successful delivery of the corresponding PDCP Data PDU has not been confirmed by lower layers, perform retransmission or transmission of all the PDCP SDUs already associated with PDCP SNs in ascending order of the COUNT values associated to the PDCP SDU prior to the PDCP entity re-establishment as specified below:   perform header compression of the PDCP SDU as specified in the subclause 5.7.4;   perform integrity protection and ciphering of the PDCP SDU using the COUNT value associated with this PDCP SDU as specified in the subclause 5.9 and 5.8;   submit the resulting PDCP Data PDU to lower layer.       

     Embodiment 1d: A method according to embodiment 1, a new IE (e.g. retransACKed) is included in the PDCP data recovery or PDCP re-establishment RRC signaling, and the PDCP will retransmit the packets that have been indicated to be missing, even if the RLC has earlier indicated those packets have been ACKed. (e.g. fastRetrans), 
     According to embodiment 1d, the PDCP recovery and re-establishment procedures become: 
     5.5 Data Recovery 
     For AM DRBs, when upper layers request a PDCP data recovery for a radio bearer, the transmitting PDCP entity shall:
         if retransACKED, is configured:
           perform retransmission of all the PDCP Data PDUs previously submitted to AM RLC entity in ascending order of the associated COUNT values.
               else:   
               perform retransmission of all the PDCP Data PDUs previously submitted to re-established or released AM RLC entity in ascending order of the associated COUNT values for which the successful delivery has not been confirmed by lower layers.   
               

     After performing the above procedures, the transmitting PDCP entity shall follow the procedures in subclause 5.2. 
     Note: it should be noted that the RLC does not need to be re-established or released to perform the recovery in the case of IAB operation. 
     5.1.2 PDCP Entity Re-Establishment 
     When upper layers request a PDCP entity re-establishment, the UE shall additionally perform once the procedures described in this section. After performing the procedures in this section, the UE shall follow the procedures in subclause 5.2. 
     When upper layers request a PDCP entity re-establishment, the transmitting PDCP entity shall:
         for UM DRBs and AM DRBs, reset the header compression protocol for uplink and start with an IR state in U-mode (as defined in RFC 3095 [8] and RFC 4815 [9]) if drb-ContinueROHC is not configured in TS 38.331 [3];   for UM DRBs and SRBs, set TX_NEXT to the initial value;   for SRBs, discard all stored PDCP SDUs and PDCP PDUs;   apply the ciphering algorithm and key provided by upper layers during the PDCP entity re-establishment procedure;   apply the integrity protection algorithm and key provided by upper layers during the PDCP entity re-establishment procedure;   for UM DRBs, for each PDCP SDU already associated with a PDCP SN but for which a corresponding PDU has not previously been submitted to lower layers:   consider the PDCP SDUs as received from upper layer;   perform transmission of the PDCP SDUs in ascending order of the COUNT value associated to the PDCP SDU prior to the PDCP re-establishment without restarting the discardTimer;   if retransACKED is configured:   from the first PDCP SDU, perform retransmission or transmission of all the PDCP SDUs already associated with PDCP SNs in ascending order of the COUNT values associated to the PDCP SDU prior to the PDCP entity re-establishment as specified below:   perform header compression of the PDCP SDU as specified in the subclause 5.7.4;   perform integrity protection and ciphering of the PDCP SDU using the COUNT value associated with this PDCP SDU as specified in the subclause 5.9 and 5.8;   submit the resulting PDCP Data PDU to lower layer.   else:
           from the first PDCP SDU for which the successful delivery of the corresponding PDCP Data PDU has not been confirmed by lower layers, perform retransmission or transmission of all the PDCP SDUs already associated with PDCP SNs in ascending order of the COUNT values associated to the PDCP SDU prior to the PDCP entity re-establishment as specified below:   
           perform header compression of the PDCP SDU as specified in the subclause 5.7.4;   perform integrity protection and ciphering of the PDCP SDU using the COUNT value associated with this PDCP SDU as specified in the subclause 5.9 and 5.8;   submit the resulting PDCP Data PDU to lower layer.       

     Embodiment 2: The network, upon finding out that the UE is connecting to it via an IAB node, configures the UE with a longer PDCP SDU discard timer as compared to UEs connected to it without relays. The discard timer discarding PDCP SDUs/PDUs for potential retransmission. 
     Embodiment 2a: A method according to embodiment 2, where the network can decide the discard timers depending on the QoS requirements of each individual bearer. Some examples:
         A bearer that is delay tolerant is configured with a longer SDU discard timer as compared to a real time bearer.   A bearer that has a very high data rate is configured with a smaller SDU discard timer as compared to a bearer that has a lower data rate (to makes sure UE buffer overflow does not occur)   Etc.       

     Embodiment 2b: A method according to embodiment 2, where the network can decide the discard timers depending on how many hops away the UE is. For example, the PDCPs of the bearers of UEs that are more hops away can be configured with longer SDU discard timers as compared to those UEs that are closer. 
     Embodiment 2c: The discard timer being started when a SDU arrives at PDCP. Alternatively a discard timer being started when an PDCP PDU (for an SDU) is transmitted. Two timers may be defined in the PDCP transmitter, one that takes over the functionality of the legacy PDCP SDU discard timer, which serves the purpose of queue management, i.e. after a certain configured time X of a PDCP SDU buffered, but not transmitted, it will be discarded. This discard will eventually be visible to higher layer protocols (like TCP) which will slow down their transmission rate, i.e. the traffic flow (IP) is more controlled. The timer expiry time is configured according to end to end flow control considerations. Another new discard timer is defined beside the existing timer, the new timer is used in IUA scenario in order to discard packets for potential retransmission, in case they are already transmitted. After a certain time after transmission, the packets are discarded and not available anymore for retransmission. This timer could be tuned according to expected latencies in the IAB scenario, i.e. depends on number of IAB hops. 
     Embodiments 2a and 2b and 2c can be combined, in pairs or all together. 
     Embodiment 3: A new information element (e.g. retransAll or relayed) is introduced in the PDCP configuration, where a PDCP configured with this IE (e.g. retransAll=TRUE), refrains from discarding PDCP packets even if they are ACKed by lower layers (i.e. discard them only when the SDU discard timer or new timer expires or a PDCP status PDU is received that confirms the SDU has been received at the receiver). 
     Embodiment 3a: An embodiment according to embodiment 3, where the network configures the UE&#39;s PDCP with this new IE when it discovers that the UE is connecting via an IAB node. 
     Embodiment 3b: An embodiment according to embodiment 3, where the network configures the UE&#39;s PDCP with this new IE even for non-relayed UEs (e.g. just based on the bearer&#39;s QoS requirements only). 
     Embodiments 3a and 3b can be combined. 
     Embodiment 3c: A method according to embodiment 3, where upon receiving a PDCP status PDU that indicates some missing packets, and the PDCP is configured with the new IE, the PDCP immediately retransmits these missing packets, even if the RLC has earlier indicated the packets have been ACKed. 
     According to embodiment 3c, the PDCP status PDU receive operation thus becomes: 
     5.4.2 Receive Operation 
     For AM DRBs, when a PDCP status report is received in the downlink, the transmitting PDCP entity shall:
         consider for each PDCP SDU, if any, with the bit in the bitmap set to ‘1’, or with the associated COUNT value less than the value of FMC field as successfully delivered, and discard the PDCP SDU as specified in the subclause 5.3.   if retransAll is configured:   perform retransmission of all the PDCP Data PDUs previously submitted to lower layers in ascending order of the associated COUNT values from the first PDCP Data PDU.       

     Embodiment 3d: A method according to embodiment 3, where upon receiving an indication to perform a PDU recovery or re-establishment from higher layers (RRC), and the PDCP is configured with the new IE, the PDCP will retransmit the packets that have been indicated to be missing, even the RLC has earlier indicated those packets have been ACKed. 
     According to embodiment 3d, the PDCP recovery and re-establishment procedures become: 
     5.5 Data Recovery 
     For AM DRBs, when upper layers request a PDCP data recovery for a radio bearer, the transmitting PDCP entity shall:
         if retransAll is configured:
           perform retransmission of all the PDCP Data PDUs previously submitted to AM RLC entity in ascending order of the associated COUNT values.
               else:   
               perform retransmission of all the PDCP Data PDUs previously submitted to re-established or released AM RLC entity in ascending order of the associated COUNT values for which the successful delivery has not been confirmed by lower layers.   
               

     After performing the above procedures, the transmitting PDCP entity shall follow the procedures in subclause 5.2. 
     5.1.2 PDCP Entity Re-Establishment 
     When upper layers request a PDCP entity re-establishment, the UE shall additionally perform once the procedures described in this section. After performing the procedures in this section, the UE shall follow the procedures in subclause 5.2. 
     When upper layers request a PDCP entity re-establishment, the transmitting PDCP entity shall:
         for UM DRBs and AM DRBs, reset the header compression protocol for uplink and start with an IR state in U-mode (as defined in RFC 3095 [8] and RFC 4815 [9]) if drb-ContinueROHC is not configured in TS 38.331 [3];   for UM DRBs and SRBs, set TX_NEXT to the initial value;   for SRBs, discard all stored PDCP SDUs and PDCP PDUs;   apply the ciphering algorithm and key provided by upper layers during the PDCP entity re-establishment procedure;   apply the integrity protection algorithm and key provided by upper layers during the PDCP entity re-establishment procedure;   for UM DRBs, for each PDCP SDU already associated with a PDCP SN but for which a corresponding PDU has not previously been submitted to lower layers:   consider the PDCP SDUs as received from upper layer;   perform transmission of the PDCP SDUs in ascending order of the COUNT value associated to the PDCP SDU prior to the PDCP re-establishment without restarting the discardTimer;   for AM DRBs,   if retransAll is configured:   from the first PDCP SDU, perform retransmission or transmission of all the PDCP SDUs already associated with PDCP SNs in ascending order of the COUNT values associated to the PDCP SDU prior to the PDCP entity re-establishment as specified below:   perform header compression of the PDCP SDU as specified in the subclause 5.7.4;   perform integrity protection and ciphering of the PDCP SDU using the COUNT value associated with this PDCP SDU as specified in the subclause 5.9 and 5.8;   submit the resulting PDCP Data PDU to lower layer.   else:
           from the first PDCP SDU for which the successful delivery of the corresponding PDCP Data PDU has not been confirmed by lower layers, perform retransmission or transmission of all the PDCP SDUs already associated with PDCP SNs in ascending order of the COUNT values associated to the PDCP SDU prior to the PDCP entity re-establishment as specified below:   perform header compression of the PDCP SDU as specified in the subclause 5.7.4;   perform integrity protection and ciphering of the PDCP SDU using the COUNT value associated with this PDCP SDU as specified in the subclause 5.9 and 5.8;   submit the resulting PDCP Data PDU to lower layer.   
               

     EMBODIMENTS RELATED TO RLC 
     Embodiment 1: The RLC of the UE is configured to NOT indicate or to delay the indication of successful delivery of PDCP PDUs to PDCP. New information elements can be introduced in the RLC configuration that specify this. This way, PDPC is NOT informed about successful transmission of a packet, and thus PDCP will not discard packets for potential retransmission. This way, ACKing of packets transmitted via the link UE to last IAB, and ACKing over all IAB hops are separated. Some examples:
         stopIndication: when configured, RLC doesn&#39;t indicate the successful indication of PDCP PDUs to PDCP layer   delayIndication: The amount of time the RLC waits to send an indication of successful delivery of PDCP PDUs to PDCP layer   groupIndication: The RLC sends indication only when a certain number of PDCP PDUs (as specified by this parameter) have been successfully delivered, and the indication in this case specifies the PDUs that were delivered. This can be done by using a bitmap, for example, that contains 1 for successful delivery and 0 otherwise, and the start and/or end sequence number of the PDUs that this bitmap refers to.   IndicationPeriod: The RLC sends indication only every Indicationperiod. If no PDCP PDUs have been delivered successfully during this period, no indication will be sent. If multiple PDUs have been delivered, a bitmap can be used (as discussed above).       

     Note that the above ways of delaying the indication can be combined (e.g. indicate either when Indicationperiod timer expires or a groupIndication number of PDUs have been delivered, whichever happens first) 
     Embodiment 2: A method according embodiment 1, where the network configures the UE to not indicate, delay indications or aggregate indications, when it realizes that the UE is connecting via relays (IAB nodes). 
     Embodiment 3: A method according to embodiment 2, where the network, when realizing the UE is connected via an IAB node, decides to increase the t-PollRetransmit value of the RLC so that UE will not be sending polls to trigger the sending of RLC status PDUs (by the corresponding RLC entity in the network) too often. 
     Embodiment 3a: A method according to embodiment 3, where the network decides the t-PollRetransmit timer based on how many hops away the UE is (e.g. a UE connected via n hops maybe configured with a t-PollRetransmitt timer value that is smaller than a UE connected via n+1 hops). 
     Embodiment 4: A method according to embodiment 2, where the network, when realizing the UE is connected via an IAB node, decides to increase the t-StatusProhibit value of the RLC at the receiver (for UL traffic, this will be the RLC entity at the network corresponding to the concerned bearer) so that the network will not send RLC status PDUs too often. 
     Embodiment 4a: A method according to embodiment 4, where the network decides the t-StatusProhibit timer based on how many hops away the UE is (e.g. the RLC entity (or entities) at the network side corresponding to a UE connected via n hops maybe configured with a t-StatusProhibit timer value that is smaller than for a UE connected via n+1 hops). 
     Embodiment 5: A method according to embodiment 2, where the network, when realizing the UE is connected via an IAB node, decides to increase the maxRetrxThreshold value of the UE&#39;s RLC so that RLF will not be triggered earlier. 
     Embodiment 5a: A method according to embodiment 5, where the network decides the maxRetrxThreshold value of the UE&#39;s RLC based on how many hops away the UE is (e.g. a UE connected via n hops maybe configured with a maxRetrxThreshold value that is smaller than for a UE connected via n+1 hops). 
     Embodiment 6: A method according to previous embodiments, where the network sends RLC status PDUs, even without being polled, when it realizes that the UE is connected via an IAB node, so that the UE can delete the already received PDUs faster from the retransmission buffer and thereby prevent buffer overflow or SDU discard. 
     Embodiment 6a: A method according to embodiment 6, where the network sends the RLC status PDUs only when it is indicating all ACKs (i.e. a certain number of packets were received in sequence). 
     Embodiment 6b: A method according to embodiment 6, where the network sends the RLC status PDUs, including only the PDUs that have been received in sequence (e.g. if PDUs 1, 2, 3, 4, 6, and 7 are received, the status PDU sent will include only an ACK for 1, 2, 3 and 4 as compared to a normal status PDU that would have indicated also an ACK for 6 and 7 as well as a NACK for 5). 
       FIG.  12    is a flow chart, depicting a method performed by a wireless device for transmitting PDCP packets over a multi-hop path to a receiver, in accordance with particular embodiments. The method begins at step  1202  with receiving PDCP signalling indicating that at least one transmitted PDCP packet has not been received. For example, the PDCP signalling may comprise a PDCP status PDU, or may comprise PDCP data recovery or PDCP re-establishment RRC signalling. 
     In response to receiving the PDCP signalling indicating that at least one transmitted PDCP packet has not been received, at step  1204  the wireless device retransmits the at least one transmitted PDCP packet that has not been received, even if said transmitted PDCP packet has been acknowledged by a lower protocol layer. 
       FIG.  13    is a flow chart, depicting a method performed by a network node in accordance with particular embodiments. The method begins at step  1302  with determining whether a wireless device is connecting to the network via an IAB node. At step  1304 , if it is determined that the wireless device is not connecting to the network via an IAB node, the network node configures the wireless device with a first PDCP SDU discard timer, and, if it is determined that the wireless device is connecting to the network via an IAB node, the network node configures the wireless device with a second PDCP SDU discard timer that is longer than the first PDCP SDU discard timer. 
     Although the subject matter described herein can be implemented in any appropriate type of system using any suitable components, the embodiments disclosed herein are described in relation to a wireless network, such as the example wireless network illustrated in  FIG.  14   . For simplicity, the wireless network of  FIG.  14    only depicts network  1406 , network nodes  1460  and  1460   b , and WDs  1410 ,  1410   b , and  1410   c . In practice, a wireless network can further include any additional elements suitable to support communication between wireless devices or between a wireless device and another communication device, such as a landline telephone, a service provider, or any other network node or end device. Of the illustrated components, network node  1460  and wireless device (WD)  1410  are depicted with additional detail. The wireless network can provide communication and other types of services to one or more wireless devices to facilitate the wireless devices&#39; access to and/or use of the services provided by, or via, the wireless network. 
     The wireless network can comprise and/or interface with any type of communication, telecommunication, data, cellular, and/or radio network or other similar type of system. In some embodiments, the wireless network can be configured to operate according to specific standards or other types of predefined rules or procedures. Thus, particular embodiments of the wireless network can implement communication standards, such as Global System for Mobile Communications (GSM), Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE), and/or other suitable 2G, 3G, 4G, or 5G standards; wireless local area network (WLAN) standards, such as the IEEE 802.11 standards; and/or any other appropriate wireless communication standard, such as the Worldwide Interoperability for Microwave Access (WiMax), Bluetooth, Z-Wave and/or ZigBee standards. 
     Network  1406  can comprise one or more backhaul networks, core networks, IP networks, public switched telephone networks (PSTNs), packet data networks, optical networks, wide-area networks (WANs), local area networks (LANs), wireless local area networks (WLANs), wired networks, wireless networks, metropolitan area networks, and other networks to enable communication between devices. 
     Network node  1460  and WD  1410  comprise various components described in more detail below. These components work together in order to provide network node and/or wireless device functionality, such as providing wireless connections in a wireless network. In different embodiments, the wireless network can comprise any number of wired or wireless networks, network nodes, base stations, controllers, wireless devices, relay stations, and/or any other components or systems that can facilitate or participate in the communication of data and/or signals whether via wired or wireless connections. 
     As used herein, network node refers to equipment capable, configured, arranged and/or operable to communicate directly or indirectly with a wireless device and/or with other network nodes or equipment in the wireless network to enable and/or provide wireless access to the wireless device and/or to perform other functions (e.g., administration) in the wireless network. Examples of network nodes include, but are not limited to, access points (APs) (e.g., radio access points), base stations (BSs) (e.g., radio base stations, Node Bs, evolved Node Bs (eNBs) and NR NodeBs (gNBs)). Base stations can be categorized based on the amount of coverage they provide (or, stated differently, their transmit power level) and can then also be referred to as femto base stations, pico base stations, micro base stations, or macro base stations. A base station can be a relay node or a relay donor node controlling a relay. A network node can also include one or more (or all) parts of a distributed radio base station such as centralized digital units and/or remote radio units (RRUs), sometimes referred to as Remote Radio Heads (RRHs). Such remote radio units may or may not be integrated with an antenna as an antenna integrated radio. Parts of a distributed radio base station can also be referred to as nodes in a distributed antenna system (DAS). 
     Further examples of network nodes include multi-standard radio (MSR) equipment such as MSR BSs, network controllers such as radio network controllers (RNCs) or base station controllers (BSCs), base transceiver stations (BTSs), transmission points, transmission nodes, multi-cell/multicast coordination entities (MCEs), core network nodes (e.g., MSCs, MMEs), O&amp;M nodes, OSS nodes, SON nodes, positioning nodes (e.g., E-SMLCs), and/or MDTs. As another example, a network node can be a virtual network node as described in more detail below. More generally, however, network nodes can represent any suitable device (or group of devices) capable, configured, arranged, and/or operable to enable and/or provide a wireless device with access to the wireless network or to provide some service to a wireless device that has accessed the wireless network. 
     In  FIG.  14   , network node  1460  includes processing circuitry  1470 , device readable medium  1480 , interface  1490 , auxiliary equipment  1484 , power source  1486 , power circuitry  1487 , and antenna  1462 . Although network node  1460  illustrated in the example wireless network of  FIG.  14    can represent a device that includes the illustrated combination of hardware components, other embodiments can comprise network nodes with different combinations of components. It is to be understood that a network node comprises any suitable combination of hardware and/or software needed to perform the tasks, features, functions and methods and/or procedures disclosed herein. Moreover, while the components of network node  1460  are depicted as single boxes located within a larger box, or nested within multiple boxes, in practice, a network node can comprise multiple different physical components that make up a single illustrated component (e.g., device readable medium  1480  can comprise multiple separate hard drives as well as multiple RAM modules). 
     Similarly, network node  1460  can be composed of multiple physically separate components (e.g., a NodeB component and a RNC component, or a BTS component and a BSC component, etc.), which can each have their own respective components. In certain scenarios in which network node  1460  comprises multiple separate components (e.g., BTS and BSC components), one or more of the separate components can be shared among several network nodes. For example, a single RNC can control multiple NodeB&#39;s. In such a scenario, each unique NodeB and RNC pair, can in some instances be considered a single separate network node. In some embodiments, network node  1460  can be configured to support multiple radio access technologies (RATs). In such embodiments, some components can be duplicated (e.g., separate device readable medium  1480  for the different RATs) and some components can be reused (e.g., the same antenna  1462  can be shared by the RATs). Network node  1460  can also include multiple sets of the various illustrated components for different wireless technologies integrated into network node  1460 , such as, for example, GSM, WCDMA, LTE, NR, WiFi, or Bluetooth wireless technologies. These wireless technologies can be integrated into the same or different chip or set of chips and other components within network node  1460 . 
     Processing circuitry  1470  can be configured to perform any determining, calculating, or similar operations (e.g., certain obtaining operations) described herein as being provided by a network node. These operations performed by processing circuitry  1470  can include processing information obtained by processing circuitry  1470  by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored in the network node, and/or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. 
     Processing circuitry  1470  can comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software and/or encoded logic operable to provide, either alone or in conjunction with other network node  1460  components, such as device readable medium  1480 , network node  1460  functionality. For example, processing circuitry  1470  can execute instructions stored in device readable medium  1480  or in memory within processing circuitry  1470 . Such functionality can include providing any of the various wireless features, functions, or benefits discussed herein. In some embodiments, processing circuitry  1470  can include a system on a chip (SOC). 
     In some embodiments, processing circuitry  1470  can include one or more of radio frequency (RF) transceiver circuitry  1472  and baseband processing circuitry  1474 . In some embodiments, radio frequency (RF) transceiver circuitry  1472  and baseband processing circuitry  1474  can be on separate chips (or sets of chips), boards, or units, such as radio units and digital units. In alternative embodiments, part or all of RF transceiver circuitry  1472  and baseband processing circuitry  1474  can be on the same chip or set of chips, boards, or units 
     In certain embodiments, some or all of the functionality described herein as being provided by a network node, base station, eNB or other such network device can be performed by processing circuitry  1470  executing instructions stored on device readable medium  1480  or memory within processing circuitry  1470 . In alternative embodiments, some or all of the functionality can be provided by processing circuitry  1470  without executing instructions stored on a separate or discrete device readable medium, such as in a hard-wired manner. In any of those embodiments, whether executing instructions stored on a device readable storage medium or not, processing circuitry  1470  can be configured to perform the described functionality. The benefits provided by such functionality are not limited to processing circuitry  1470  alone or to other components of network node  1460 , but are enjoyed by network node  1460  as a whole, and/or by end users and the wireless network generally. 
     Device readable medium  1480  can comprise any form of volatile or non-volatile computer readable memory including, without limitation, persistent storage, solid-state memory, remotely mounted memory, magnetic media, optical media, random access memory (RAM), read-only memory (ROM), mass storage media (for example, a hard disk), removable storage media (for example, a flash drive, a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or any other volatile or non-volatile, non-transitory device readable and/or computer-executable memory devices that store information, data, and/or instructions that can be used by processing circuitry  1470 . Device readable medium  1480  can store any suitable instructions, data or information, including a computer program, software, an application including one or more of logic, rules, code, tables, etc. and/or other instructions capable of being executed by processing circuitry  1470  and, utilized by network node  1460 . Device readable medium  1480  can be used to store any calculations made by processing circuitry  1470  and/or any data received via interface  1490 . In some embodiments, processing circuitry  1470  and device readable medium  1480  can be considered to be integrated. 
     Interface  1490  is used in the wired or wireless communication of signalling and/or data between network node  1460 , network  1406 , and/or WDs  1410 . As illustrated, interface  1490  comprises port(s)/terminal(s)  1494  to send and receive data, for example to and from network  1406  over a wired connection. Interface  1490  also includes radio front end circuitry  1492  that can be coupled to, or in certain embodiments a part of, antenna  1462 . Radio front end circuitry  1492  comprises filters  1498  and amplifiers  1496 . Radio front end circuitry  1492  can be connected to antenna  1462  and processing circuitry  1470 . Radio front end circuitry can be configured to condition signals communicated between antenna  1462  and processing circuitry  1470 . Radio front end circuitry  1492  can receive digital data that is to be sent out to other network nodes or WDs via a wireless connection. Radio front end circuitry  1492  can convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters  1498  and/or amplifiers  1496 . The radio signal can then be transmitted via antenna  1462 . Similarly, when receiving data, antenna  1462  can collect radio signals which are then converted into digital data by radio front end circuitry  1492 . The digital data can be passed to processing circuitry  1470 . In other embodiments, the interface can comprise different components and/or different combinations of components. 
     In certain alternative embodiments, network node  1460  may not include separate radio front end circuitry  1492 , instead, processing circuitry  1470  can comprise radio front end circuitry and can be connected to antenna  1462  without separate radio front end circuitry  1492 . Similarly, in some embodiments, all or some of RF transceiver circuitry  1472  can be considered a part of interface  1490 . In still other embodiments, interface  1490  can include one or more ports or terminals  1494 , radio front end circuitry  1492 , and RF transceiver circuitry  1472 , as part of a radio unit (not shown), and interface  1490  can communicate with baseband processing circuitry  1474 , which is part of a digital unit (not shown). 
     Antenna  1462  can include one or more antennas, or antenna arrays, configured to send and/or receive wireless signals. Antenna  1462  can be coupled to radio front end circuitry  1490  and can be any type of antenna capable of transmitting and receiving data and/or signals wirelessly. In some embodiments, antenna  1462  can comprise one or more omni-directional, sector or panel antennas operable to transmit/receive radio signals between, for example, 2 GHz and 66 GHz. An omni-directional antenna can be used to transmit/receive radio signals in any direction, a sector antenna can be used to transmit/receive radio signals from devices within a particular area, and a panel antenna can be a line of sight antenna used to transmit/receive radio signals in a relatively straight line. In some instances, the use of more than one antenna can be referred to as MIMO. In certain embodiments, antenna  1462  can be separate from network node  1460  and can be connectable to network node  1460  through an interface or port. 
     Antenna  1462 , interface  1490 , and/or processing circuitry  1470  can be configured to perform any receiving operations and/or certain obtaining operations described herein as being performed by a network node. Any information, data and/or signals can be received from a wireless device, another network node and/or any other network equipment. Similarly, antenna  1462 , interface  1490 , and/or processing circuitry  1470  can be configured to perform any transmitting operations described herein as being performed by a network node. Any information, data and/or signals can be transmitted to a wireless device, another network node and/or any other network equipment. 
     Power circuitry  1487  can comprise, or be coupled to, power management circuitry and can be configured to supply the components of network node  1460  with power for performing the functionality described herein. Power circuitry  1487  can receive power from power source  1486 . Power source  1486  and/or power circuitry  1487  can be configured to provide power to the various components of network node  1460  in a form suitable for the respective components (e.g., at a voltage and current level needed for each respective component). Power source  1486  can either be included in, or external to, power circuitry  1487  and/or network node  1460 . For example, network node  1460  can be connectable to an external power source (e.g., an electricity outlet) via an input circuitry or interface such as an electrical cable, whereby the external power source supplies power to power circuitry  1487 . As a further example, power source  1486  can comprise a source of power in the form of a battery or battery pack which is connected to, or integrated in, power circuitry  1487 . The battery can provide backup power should the external power source fail. Other types of power sources, such as photovoltaic devices, can also be used. 
     Alternative embodiments of network node  1460  can include additional components beyond those shown in  FIG.  14    that can be responsible for providing certain aspects of the network node&#39;s functionality, including any of the functionality described herein and/or any functionality necessary to support the subject matter described herein. For example, network node  1460  can include user interface equipment to allow and/or facilitate input of information into network node  1460  and to allow and/or facilitate output of information from network node  1460 . This can allow and/or facilitate a user to perform diagnostic, maintenance, repair, and other administrative functions for network node  1460 . 
     As used herein, wireless device (WD) refers to a device capable, configured, arranged and/or operable to communicate wirelessly with network nodes and/or other wireless devices. Unless otherwise noted, the term WD can be used interchangeably herein with user equipment (UE). Communicating wirelessly can involve transmitting and/or receiving wireless signals using electromagnetic waves, radio waves, infrared waves, and/or other types of signals suitable for conveying information through air. In some embodiments, a WD can be configured to transmit and/or receive information without direct human interaction. For instance, a WD can be designed to transmit information to a network on a predetermined schedule, when triggered by an internal or external event, or in response to requests from the network. Examples of a WD include, but are not limited to, a smart phone, a mobile phone, a cell phone, a voice over IP (VoIP) phone, a wireless local loop phone, a desktop computer, a personal digital assistant (PDA), a wireless cameras, a gaming console or device, a music storage device, a playback appliance, a wearable terminal device, a wireless endpoint, a mobile station, a tablet, a laptop, a laptop-embedded equipment (LEE), a laptop-mounted equipment (LME), a smart device, a wireless customer-premise equipment (CPE). a vehicle-mounted wireless terminal device, etc. 
     A WD can support device-to-device (D2D) communication, for example by implementing a 3GPP standard for sidelink communication, vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2I), vehicle-to-everything (V2X) and can in this case be referred to as a D2D communication device. As yet another specific example, in an Internet of Things (IoT) scenario, a WD can represent a machine or other device that performs monitoring and/or measurements, and transmits the results of such monitoring and/or measurements to another WD and/or a network node. The WD can in this case be a machine-to-machine (M2M) device, which can in a 3GPP context be referred to as an MTC device. As one particular example, the WD can be a UE implementing the 3GPP narrow band internet of things (NB-IoT) standard. Particular examples of such machines or devices are sensors, metering devices such as power meters, industrial machinery, or home or personal appliances (e.g., refrigerators, televisions, etc.) personal wearables (e.g., watches, fitness trackers, etc.). In other scenarios, a WD can represent a vehicle or other equipment that is capable of monitoring and/or reporting on its operational status or other functions associated with its operation. A WD as described above can represent the endpoint of a wireless connection, in which case the device can be referred to as a wireless terminal. Furthermore, a WD as described above can be mobile, in which case it can also be referred to as a mobile device or a mobile terminal. 
     As illustrated, wireless device  1410  includes antenna  1411 , interface  1414 , processing circuitry  1420 , device readable medium  1430 , user interface equipment  1432 , auxiliary equipment  1434 , power source  1436  and power circuitry  1437 . WD  1410  can include multiple sets of one or more of the illustrated components for different wireless technologies supported by WD  1410 , such as, for example, GSM, WCDMA, LTE, NR, WiFi, WiMAX, or Bluetooth wireless technologies, just to mention a few. These wireless technologies can be integrated into the same or different chips or set of chips as other components within WD  1410 . 
     Antenna  1411  can include one or more antennas or antenna arrays, configured to send and/or receive wireless signals, and is connected to interface  1414 . In certain alternative embodiments, antenna  1411  can be separate from WD  1410  and be connectable to WD  1410  through an interface or port. Antenna  1411 , interface  1414 , and/or processing circuitry  1420  can be configured to perform any receiving or transmitting operations described herein as being performed by a WD. Any information, data and/or signals can be received from a network node and/or another WD. In some embodiments, radio front end circuitry and/or antenna  1411  can be considered an interface. 
     As illustrated, interface  1414  comprises radio front end circuitry  1412  and antenna  1411 . Radio front end circuitry  1412  comprise one or more filters  1418  and amplifiers  1416 . Radio front end circuitry  1414  is connected to antenna  1411  and processing circuitry  1420 , and can be configured to condition signals communicated between antenna  1411  and processing circuitry  1420 . Radio front end circuitry  1412  can be coupled to or a part of antenna  1411 . In some embodiments, WD  1410  may not include separate radio front end circuitry  1412 ; rather, processing circuitry  1420  can comprise radio front end circuitry and can be connected to antenna  1411 . Similarly, in some embodiments, some or all of RF transceiver circuitry  1422  can be considered a part of interface  1414 . Radio front end circuitry  1412  can receive digital data that is to be sent out to other network nodes or WDs via a wireless connection. Radio front end circuitry  1412  can convert the digital data into a radio signal having the appropriate channel and bandwidth parameters using a combination of filters  1418  and/or amplifiers  1416 . The radio signal can then be transmitted via antenna  1411 . Similarly, when receiving data, antenna  1411  can collect radio signals which are then converted into digital data by radio front end circuitry  1412 . The digital data can be passed to processing circuitry  1420 . In other embodiments, the interface can comprise different components and/or different combinations of components. 
     Processing circuitry  1420  can comprise a combination of one or more of a microprocessor, controller, microcontroller, central processing unit, digital signal processor, application-specific integrated circuit, field programmable gate array, or any other suitable computing device, resource, or combination of hardware, software, and/or encoded logic operable to provide, either alone or in conjunction with other WD  1410  components, such as device readable medium  1430 , WD  1410  functionality. Such functionality can include providing any of the various wireless features or benefits discussed herein. For example, processing circuitry  1420  can execute instructions stored in device readable medium  1430  or in memory within processing circuitry  1420  to provide the functionality disclosed herein. 
     As illustrated, processing circuitry  1420  includes one or more of RF transceiver circuitry  1422 , baseband processing circuitry  1424 , and application processing circuitry  1426 . In other embodiments, the processing circuitry can comprise different components and/or different combinations of components. In certain embodiments processing circuitry  1420  of WD  1410  can comprise a SOC. In some embodiments, RF transceiver circuitry  1422 , baseband processing circuitry  1424 , and application processing circuitry  1426  can be on separate chips or sets of chips. In alternative embodiments, part or all of baseband processing circuitry  1424  and application processing circuitry  1426  can be combined into one chip or set of chips, and RF transceiver circuitry  1422  can be on a separate chip or set of chips. In still alternative embodiments, part or all of RF transceiver circuitry  1422  and baseband processing circuitry  1424  can be on the same chip or set of chips, and application processing circuitry  1426  can be on a separate chip or set of chips. In yet other alternative embodiments, part or all of RF transceiver circuitry  1422 , baseband processing circuitry  1424 , and application processing circuitry  1426  can be combined in the same chip or set of chips. In some embodiments, RF transceiver circuitry  1422  can be a part of interface  1414 . RF transceiver circuitry  1422  can condition RF signals for processing circuitry  1420 . 
     In certain embodiments, some or all of the functionality described herein as being performed by a WD can be provided by processing circuitry  1420  executing instructions stored on device readable medium  1430 , which in certain embodiments can be a computer-readable storage medium. In alternative embodiments, some or all of the functionality can be provided by processing circuitry  1420  without executing instructions stored on a separate or discrete device readable storage medium, such as in a hard-wired manner. In any of those particular embodiments, whether executing instructions stored on a device readable storage medium or not, processing circuitry  1420  can be configured to perform the described functionality. The benefits provided by such functionality are not limited to processing circuitry  1420  alone or to other components of WD  1410 , but are enjoyed by WD  1410  as a whole, and/or by end users and the wireless network generally. 
     Processing circuitry  1420  can be configured to perform any determining, calculating, or similar operations (e.g., certain obtaining operations) described herein as being performed by a WD. These operations, as performed by processing circuitry  1420 , can include processing information obtained by processing circuitry  1420  by, for example, converting the obtained information into other information, comparing the obtained information or converted information to information stored by WD  1410 , and/or performing one or more operations based on the obtained information or converted information, and as a result of said processing making a determination. 
     Device readable medium  1430  can be operable to store a computer program, software, an application including one or more of logic, rules, code, tables, etc. and/or other instructions capable of being executed by processing circuitry  1420 . Device readable medium  1430  can include computer memory (e.g., Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (e.g., a hard disk), removable storage media (e.g., a Compact Disk (CD) or a Digital Video Disk (DVD)), and/or any other volatile or non-volatile, non-transitory device readable and/or computer executable memory devices that store information, data, and/or instructions that can be used by processing circuitry  1420 . In some embodiments, processing circuitry  1420  and device readable medium  1430  can be considered to be integrated. 
     User interface equipment  1432  can include components that allow and/or facilitate a human user to interact with WD  1410 . Such interaction can be of many forms, such as visual, audial, tactile, etc. User interface equipment  1432  can be operable to produce output to the user and to allow and/or facilitate the user to provide input to WD  1410 . The type of interaction can vary depending on the type of user interface equipment  1432  installed in WD  1410 . For example, if WD  1410  is a smart phone, the interaction can be via a touch screen; if WD  1410  is a smart meter, the interaction can be through a screen that provides usage (e.g., the number of gallons used) or a speaker that provides an audible alert (e.g., if smoke is detected). User interface equipment  1432  can include input interfaces, devices and circuits, and output interfaces, devices and circuits. User interface equipment  1432  can be configured to allow and/or facilitate input of information into WD  1410 , and is connected to processing circuitry  1420  to allow and/or facilitate processing circuitry  1420  to process the input information. User interface equipment  1432  can include, for example, a microphone, a proximity or other sensor, keys/buttons, a touch display, one or more cameras, a USB port, or other input circuitry. User interface equipment  1432  is also configured to allow and/or facilitate output of information from WD  1410 , and to allow and/or facilitate processing circuitry  1420  to output information from WD  1410 . User interface equipment  1432  can include, for example, a speaker, a display, vibrating circuitry, a USB port, a headphone interface, or other output circuitry. Using one or more input and output interfaces, devices, and circuits, of user interface equipment  1432 , WD  1410  can communicate with end users and/or the wireless network, and allow and/or facilitate them to benefit from the functionality described herein. 
     Auxiliary equipment  1434  is operable to provide more specific functionality which may not be generally performed by WDs. This can comprise specialized sensors for doing measurements for various purposes, interfaces for additional types of communication such as wired communications etc. The inclusion and type of components of auxiliary equipment  1434  can vary depending on the embodiment and/or scenario. 
     Power source  1436  can, in some embodiments, be in the form of a battery or battery pack. Other types of power sources, such as an external power source (e.g., an electricity outlet), photovoltaic devices or power cells, can also be used. WD  1410  can further comprise power circuitry  1437  for delivering power from power source  1436  to the various parts of WD  1410  which need power from power source  1436  to carry out any functionality described or indicated herein. Power circuitry  1437  can in certain embodiments comprise power management circuitry. Power circuitry  1437  can additionally or alternatively be operable to receive power from an external power source; in which case WD  1410  can be connectable to the external power source (such as an electricity outlet) via input circuitry or an interface such as an electrical power cable. Power circuitry  1437  can also in certain embodiments be operable to deliver power from an external power source to power source  1436 . This can be, for example, for the charging of power source  1436 . Power circuitry  1437  can perform any converting or other modification to the power from power source  1436  to make it suitable for supply to the respective components of WD  1410 . 
       FIG.  15    illustrates one embodiment of a UE in accordance with various aspects described herein. As used herein, a user equipment or UE may not necessarily have a user in the sense of a human user who owns and/or operates the relevant device. Instead, a UE can represent a device that is intended for sale to, or operation by, a human user but which may not, or which may not initially, be associated with a specific human user (e.g., a smart sprinkler controller). Alternatively, a UE can represent a device that is not intended for sale to, or operation by, an end user but which can be associated with or operated for the benefit of a user (e.g., a smart power meter). UE  1500  can be any UE identified by the 3 rd  Generation Partnership Project (3GPP), including a NB-IoT UE, a machine type communication (MTC) UE, and/or an enhanced MTC (eMTC) UE. UE  1500 , as illustrated in  FIG.  15   , is one example of a WD configured for communication in accordance with one or more communication standards promulgated by the 3 rd  Generation Partnership Project (3GPP), such as 3GPP&#39;s GSM, UMTS, LTE, and/or 5G standards. As mentioned previously, the term WD and UE can be used interchangeable. Accordingly, although  FIG.  15    is a UE, the components discussed herein are equally applicable to a WD, and vice-versa. 
     In  FIG.  15   , UE  1500  includes processing circuitry  1501  that is operatively coupled to input/output interface  1505 , radio frequency (RF) interface  1509 , network connection interface  1511 , memory  1515  including random access memory (RAM)  1517 , read-only memory (ROM)  1519 , and storage medium  1521  or the like, communication subsystem  1531 , power source  1533 , and/or any other component, or any combination thereof. Storage medium  1521  includes operating system  1523 , application program  1525 , and data  1527 . In other embodiments, storage medium  1521  can include other similar types of information. Certain UEs can utilize all of the components shown in  FIG.  15   , or only a subset of the components. The level of integration between the components can vary from one UE to another UE. Further, certain UEs can contain multiple instances of a component, such as multiple processors, memories, transceivers, transmitters, receivers, etc. 
     In  FIG.  15   , processing circuitry  1501  can be configured to process computer instructions and data. Processing circuitry  1501  can be configured to implement any sequential state machine operative to execute machine instructions stored as machine-readable computer programs in the memory, such as one or more hardware-implemented state machines (e.g., in discrete logic, FPGA, ASIC, etc.); programmable logic together with appropriate firmware; one or more stored program, general-purpose processors, such as a microprocessor or Digital Signal Processor (DSP), together with appropriate software; or any combination of the above. For example, the processing circuitry  1501  can include two central processing units (CPUs). Data can be information in a form suitable for use by a computer. 
     In the depicted embodiment, input/output interface  1505  can be configured to provide a communication interface to an input device, output device, or input and output device. UE  1500  can be configured to use an output device via input/output interface  1505 . An output device can use the same type of interface port as an input device. For example, a USB port can be used to provide input to and output from UE  1500 . The output device can be a speaker, a sound card, a video card, a display, a monitor, a printer, an actuator, an emitter, a smartcard, another output device, or any combination thereof. UE  1500  can be configured to use an input device via input/output interface  1505  to allow and/or facilitate a user to capture information into UE  1500 . The input device can include a touch-sensitive or presence-sensitive display, a camera (e.g., a digital camera, a digital video camera, a web camera, etc.), a microphone, a sensor, a mouse, a trackball, a directional pad, a trackpad, a scroll wheel, a smartcard, and the like. The presence-sensitive display can include a capacitive or resistive touch sensor to sense input from a user. A sensor can be, for instance, an accelerometer, a gyroscope, a tilt sensor, a force sensor, a magnetometer, an optical sensor, a proximity sensor, another like sensor, or any combination thereof. For example, the input device can be an accelerometer, a magnetometer, a digital camera, a microphone, and an optical sensor. 
     In  FIG.  15   , RF interface  1509  can be configured to provide a communication interface to RF components such as a transmitter, a receiver, and an antenna. Network connection interface  1511  can be configured to provide a communication interface to network  1543   a . Network  1543   a  can encompass wired and/or wireless networks such as a local-area network (LAN), a wide-area network (WAN), a computer network, a wireless network, a telecommunications network, another like network or any combination thereof. For example, network  1543   a  can comprise a Wi-Fi network. Network connection interface  1511  can be configured to include a receiver and a transmitter interface used to communicate with one or more other devices over a communication network according to one or more communication protocols, such as Ethernet, TCP/IP, SONET, ATM, or the like. Network connection interface  1511  can implement receiver and transmitter functionality appropriate to the communication network links (e.g., optical, electrical, and the like). The transmitter and receiver functions can share circuit components, software or firmware, or alternatively can be implemented separately. 
     RAM  1517  can be configured to interface via bus  1502  to processing circuitry  1501  to provide storage or caching of data or computer instructions during the execution of software programs such as the operating system, application programs, and device drivers. ROM  1519  can be configured to provide computer instructions or data to processing circuitry  1501 . For example, ROM  1519  can be configured to store invariant low-level system code or data for basic system functions such as basic input and output (I/O), startup, or reception of keystrokes from a keyboard that are stored in a non-volatile memory. Storage medium  1521  can be configured to include memory such as RAM, ROM, programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), magnetic disks, optical disks, floppy disks, hard disks, removable cartridges, or flash drives. In one example, storage medium  1521  can be configured to include operating system  1523 , application program  1525  such as a web browser application, a widget or gadget engine or another application, and data file  1527 . Storage medium  1521  can store, for use by UE  1500 , any of a variety of various operating systems or combinations of operating systems. 
     Storage medium  1521  can be configured to include a number of physical drive units, such as redundant array of independent disks (RAID), floppy disk drive, flash memory, USB flash drive, external hard disk drive, thumb drive, pen drive, key drive, high-density digital versatile disc (HD-DVD) optical disc drive, internal hard disk drive, Blu-Ray optical disc drive, holographic digital data storage (HDDS) optical disc drive, external mini-dual in-line memory module (DIMM), synchronous dynamic random access memory (SDRAM), external micro-DIMM SDRAM, smartcard memory such as a subscriber identity module or a removable user identity (SIM/RUIM) module, other memory, or any combination thereof. Storage medium  1521  can allow and/or facilitate UE  1500  to access computer-executable instructions, application programs or the like, stored on transitory or non-transitory memory media, to off-load data, or to upload data. An article of manufacture, such as one utilizing a communication system can be tangibly embodied in storage medium  1521 , which can comprise a device readable medium. 
     In  FIG.  15   , processing circuitry  1501  can be configured to communicate with network  1543   b  using communication subsystem  1531 . Network  1543   a  and network  1543   b  can be the same network or networks or different network or networks. Communication subsystem  1531  can be configured to include one or more transceivers used to communicate with network  1543   b . For example, communication subsystem  1531  can be configured to include one or more transceivers used to communicate with one or more remote transceivers of another device capable of wireless communication such as another WD, UE, or base station of a radio access network (RAN) according to one or more communication protocols, such as IEEE 802.15, CDMA, WCDMA, GSM, LTE, UTRAN, WiMax, or the like. Each transceiver can include transmitter  1533  and/or receiver  1535  to implement transmitter or receiver functionality, respectively, appropriate to the RAN links (e.g., frequency allocations and the like). Further, transmitter  1533  and receiver  1535  of each transceiver can share circuit components, software or firmware, or alternatively can be implemented separately. 
     In the illustrated embodiment, the communication functions of communication subsystem  1531  can include data communication, voice communication, multimedia communication, short-range communications such as Bluetooth, near-field communication, location-based communication such as the use of the global positioning system (GPS) to determine a location, another like communication function, or any combination thereof. For example, communication subsystem  1531  can include cellular communication, Wi-Fi communication, Bluetooth communication, and GPS communication. Network  1543   b  can encompass wired and/or wireless networks such as a local-area network (LAN), a wide-area network (WAN), a computer network, a wireless network, a telecommunications network, another like network or any combination thereof. For example, network  1543   b  can be a cellular network, a Wi-Fi network, and/or a near-field network. Power source  1513  can be configured to provide alternating current (AC) or direct current (DC) power to components of UE  1500 . 
     The features, benefits and/or functions described herein can be implemented in one of the components of UE  1500  or partitioned across multiple components of UE  1500 . Further, the features, benefits, and/or functions described herein can be implemented in any combination of hardware, software or firmware. In one example, communication subsystem  1531  can be configured to include any of the components described herein. Further, processing circuitry  1501  can be configured to communicate with any of such components over bus  1502 . In another example, any of such components can be represented by program instructions stored in memory that when executed by processing circuitry  1501  perform the corresponding functions described herein. In another example, the functionality of any of such components can be partitioned between processing circuitry  1501  and communication subsystem  1531 . In another example, the non-computationally intensive functions of any of such components can be implemented in software or firmware and the computationally intensive functions can be implemented in hardware. 
       FIG.  16    is a schematic block diagram illustrating a virtualization environment  1600  in which functions implemented by some embodiments can be virtualized. In the present context, virtualizing means creating virtual versions of apparatuses or devices which can include virtualizing hardware platforms, storage devices and networking resources. As used herein, virtualization can be applied to a node (e.g., a virtualized base station or a virtualized radio access node) or to a device (e.g., a UE, a wireless device or any other type of communication device) or components thereof and relates to an implementation in which at least a portion of the functionality is implemented as one or more virtual components (e.g., via one or more applications, components, functions, virtual machines or containers executing on one or more physical processing nodes in one or more networks). 
     In some embodiments, some or all of the functions described herein can be implemented as virtual components executed by one or more virtual machines implemented in one or more virtual environments  1600  hosted by one or more of hardware nodes  1630 . Further, in embodiments in which the virtual node is not a radio access node or does not require radio connectivity (e.g., a core network node), then the network node can be entirely virtualized. 
     The functions can be implemented by one or more applications  1620  (which can alternatively be called software instances, virtual appliances, network functions, virtual nodes, virtual network functions, etc.) operative to implement some of the features, functions, and/or benefits of some of the embodiments disclosed herein. Applications  1620  are run in virtualization environment  1600  which provides hardware  1630  comprising processing circuitry  1660  and memory  1690 . Memory  1690  contains instructions  1695  executable by processing circuitry  1660  whereby application  1620  is operative to provide one or more of the features, benefits, and/or functions disclosed herein. 
     Virtualization environment  1600 , comprises general-purpose or special-purpose network hardware devices  1630  comprising a set of one or more processors or processing circuitry  1660 , which can be commercial off-the-shelf (COTS) processors, dedicated Application Specific Integrated Circuits (ASICs), or any other type of processing circuitry including digital or analog hardware components or special purpose processors. Each hardware device can comprise memory  1690 - 1  which can be non-persistent memory for temporarily storing instructions  1695  or software executed by processing circuitry  1660 . Each hardware device can comprise one or more network interface controllers (NICs)  1670 , also known as network interface cards, which include physical network interface  1680 . Each hardware device can also include non-transitory, persistent, machine-readable storage media  1690 - 2  having stored therein software  1695  and/or instructions executable by processing circuitry  1660 . Software  1695  can include any type of software including software for instantiating one or more virtualization layers  1650  (also referred to as hypervisors), software to execute virtual machines  1640  as well as software allowing it to execute functions, features and/or benefits described in relation with some embodiments described herein. 
     Virtual machines  1640 , comprise virtual processing, virtual memory, virtual networking or interface and virtual storage, and can be run by a corresponding virtualization layer  1650  or hypervisor. Different embodiments of the instance of virtual appliance  1620  can be implemented on one or more of virtual machines  1640 , and the implementations can be made in different ways. 
     During operation, processing circuitry  1660  executes software  1695  to instantiate the hypervisor or virtualization layer  1650 , which can sometimes be referred to as a virtual machine monitor (VMM). Virtualization layer  1650  can present a virtual operating platform that appears like networking hardware to virtual machine  1640 . 
     As shown in  FIG.  16   , hardware  1630  can be a standalone network node with generic or specific components. Hardware  1630  can comprise antenna  16225  and can implement some functions via virtualization. Alternatively, hardware  1630  can be part of a larger cluster of hardware (e.g., such as in a data center or customer premise equipment (CPE)) where many hardware nodes work together and are managed via management and orchestration (MANO)  16100 , which, among others, oversees lifecycle management of applications  1620 . 
     Virtualization of the hardware is in some contexts referred to as network function virtualization (NFV). NFV can be used to consolidate many network equipment types onto industry standard high volume server hardware, physical switches, and physical storage, which can be located in data centers, and customer premise equipment. 
     In the context of NFV, virtual machine  1640  can be a software implementation of a physical machine that runs programs as if they were executing on a physical, non-virtualized machine. Each of virtual machines  1640 , and that part of hardware  1630  that executes that virtual machine, be it hardware dedicated to that virtual machine and/or hardware shared by that virtual machine with others of the virtual machines  1640 , forms a separate virtual network elements (VNE). 
     Still in the context of NFV, Virtual Network Function (VNF) is responsible for handling specific network functions that run in one or more virtual machines  1640  on top of hardware networking infrastructure  1630  and corresponds to application  1620  in  FIG.  16   . 
     In some embodiments, one or more radio units  16200  that each include one or more transmitters  16220  and one or more receivers  16210  can be coupled to one or more antennas  16225 . Radio units  16200  can communicate directly with hardware nodes  1630  via one or more appropriate network interfaces and can be used in combination with the virtual components to provide a virtual node with radio capabilities, such as a radio access node or a base station. 
     In some embodiments, some signalling can be effected with the use of control system  16230  which can alternatively be used for communication between the hardware nodes  1630  and radio units  16200 . 
     With reference to  FIG.  17   , in accordance with an embodiment, a communication system includes telecommunication network  1710 , such as a 3GPP-type cellular network, which comprises access network  1711 , such as a radio access network, and core network  1714 . Access network  1711  comprises a plurality of base stations  1712   a ,  1712   b ,  1712   c , such as NBs, eNBs, gNBs or other types of wireless access points, each defining a corresponding coverage area  1713   a ,  1713   b ,  1713   c . Each base station  1712   a ,  1712   b ,  1712   c  is connectable to core network  1714  over a wired or wireless connection  1715 . A first UE  1791  located in coverage area  1713   c  can be configured to wirelessly connect to, or be paged by, the corresponding base station  1712   c . A second UE  1792  in coverage area  1713   a  is wirelessly connectable to the corresponding base station  1712   a . While a plurality of UEs  1791 ,  1792  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  1712 . 
     Telecommunication network  1710  is itself connected to host computer  1730 , which can 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. Host computer  1730  can be under the ownership or control of a service provider, or can be operated by the service provider or on behalf of the service provider. Connections  1721  and  1722  between telecommunication network  1710  and host computer  1730  can extend directly from core network  1714  to host computer  1730  or can go via an optional intermediate network  1720 . Intermediate network  1720  can be one of, or a combination of more than one of, a public, private or hosted network; intermediate network  1720 , if any, can be a backbone network or the Internet; in particular, intermediate network  1720  can comprise two or more sub-networks (not shown). 
     The communication system of  FIG.  17    as a whole enables connectivity between the connected UEs  1791 ,  1792  and host computer  1730 . The connectivity can be described as an over-the-top (OTT) connection  1750 . Host computer  1730  and the connected UEs  1791 ,  1792  are configured to communicate data and/or signaling via OTT connection  1750 , using access network  1711 , core network  1714 , any intermediate network  1720  and possible further infrastructure (not shown) as intermediaries. OTT connection  1750  can be transparent in the sense that the participating communication devices through which OTT connection  1750  passes are unaware of routing of uplink and downlink communications. For example, base station  1712  may not or need not be informed about the past routing of an incoming downlink communication with data originating from host computer  1730  to be forwarded (e.g., handed over) to a connected UE  1791 . Similarly, base station  1712  need not be aware of the future routing of an outgoing uplink communication originating from the UE  1791  towards the host computer  1730 . 
     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  FIG.  18   . In communication system  1800 , host computer  1810  comprises hardware  1815  including communication interface  1816  configured to set up and maintain a wired or wireless connection with an interface of a different communication device of communication system  1800 . Host computer  1810  further comprises processing circuitry  1818 , which can have storage and/or processing capabilities. In particular, processing circuitry  1818  can comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. Host computer  1810  further comprises software  1811 , which is stored in or accessible by host computer  1810  and executable by processing circuitry  1818 . Software  1811  includes host application  1812 . Host application  1812  can be operable to provide a service to a remote user, such as UE  1830  connecting via OTT connection  1850  terminating at UE  1830  and host computer  1810 . In providing the service to the remote user, host application  1812  can provide user data which is transmitted using OTT connection  1850 . 
     Communication system  1800  can also include base station  1820  provided in a telecommunication system and comprising hardware  1825  enabling it to communicate with host computer  1810  and with UE  1830 . Hardware  1825  can include communication interface  1826  for setting up and maintaining a wired or wireless connection with an interface of a different communication device of communication system  1800 , as well as radio interface  1827  for setting up and maintaining at least wireless connection  1870  with UE  1830  located in a coverage area (not shown in  FIG.  18   ) served by base station  1820 . Communication interface  1826  can be configured to facilitate connection  1860  to host computer  1810 . Connection  1860  can be direct or it can pass through a core network (not shown in  FIG.  18   ) of the telecommunication system and/or through one or more intermediate networks outside the telecommunication system. In the embodiment shown, hardware  1825  of base station  1820  can also include processing circuitry  1828 , which can comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. Base station  1820  further has software  1821  stored internally or accessible via an external connection. 
     Communication system  1800  can also include UE  1830  already referred to. Its hardware  1835  can include radio interface  1837  configured to set up and maintain wireless connection  1870  with a base station serving a coverage area in which UE  1830  is currently located. Hardware  1835  of UE  1830  can also include processing circuitry  1838 , which can comprise one or more programmable processors, application-specific integrated circuits, field programmable gate arrays or combinations of these (not shown) adapted to execute instructions. UE  1830  further comprises software  1831 , which is stored in or accessible by UE  1830  and executable by processing circuitry  1838 . Software  1831  includes client application  1832 . Client application  1832  can be operable to provide a service to a human or non-human user via UE  1830 , with the support of host computer  1810 . In host computer  1810 , an executing host application  1812  can communicate with the executing client application  1832  via OTT connection  1850  terminating at UE  1830  and host computer  1810 . In providing the service to the user, client application  1832  can receive request data from host application  1812  and provide user data in response to the request data. OTT connection  1850  can transfer both the request data and the user data. Client application  1832  can interact with the user to generate the user data that it provides. 
     It is noted that host computer  1810 , base station  1820  and UE  1830  illustrated in  FIG.  18    can be similar or identical to host computer  1730 , one of base stations  1712   a ,  1712   b ,  1712   c  and one of UEs  1791 ,  1792  of  FIG.  17   , respectively. This is to say, the inner workings of these entities can be as shown in  FIG.  18    and independently, the surrounding network topology can be that of  FIG.  17   . 
     In  FIG.  18   , OTT connection  1850  has been drawn abstractly to illustrate the communication between host computer  1810  and UE  1830  via base station  1820 , without explicit reference to any intermediary devices and the precise routing of messages via these devices. Network infrastructure can determine the routing, which it can be configured to hide from UE  1830  or from the service provider operating host computer  1810 , or both. While OTT connection  1850  is active, the network infrastructure can further take decisions by which it dynamically changes the routing (e.g., on the basis of load balancing consideration or reconfiguration of the network). 
     Wireless connection  1870  between UE  1830  and base station  1820  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 UE  1830  using OTT connection  1850 , in which wireless connection  1870  forms the last segment. More precisely, the exemplary embodiments disclosed herein can improve flexibility for the network to monitor end-to-end quality-of-service (QoS) of data flows, including their corresponding radio bearers, associated with data sessions between a user equipment (UE) and another entity, such as an OTT data application or service external to the 5G network. These and other advantages can facilitate more timely design, implementation, and deployment of 5G/NR solutions. Furthermore, such embodiments can facilitate flexible and timely control of data session QoS, which can lead to improvements in capacity, throughput, latency, etc. that are envisioned by 5G/NR and important for the growth of OTT services. 
     A measurement procedure can be provided for the purpose of monitoring data rate, latency and other network operational aspects on which the one or more embodiments improve. There can further be an optional network functionality for reconfiguring OTT connection  1850  between host computer  1810  and UE  1830 , in response to variations in the measurement results. The measurement procedure and/or the network functionality for reconfiguring OTT connection  1850  can be implemented in software  1811  and hardware  1815  of host computer  1810  or in software  1831  and hardware  1835  of UE  1830 , or both. In embodiments, sensors (not shown) can be deployed in or in association with communication devices through which OTT connection  1850  passes; the sensors can participate in the measurement procedure by supplying values of the monitored quantities exemplified above, or supplying values of other physical quantities from which software  1811 ,  1831  can compute or estimate the monitored quantities. The reconfiguring of OTT connection  1850  can include message format, retransmission settings, preferred routing etc.; the reconfiguring need not affect base station  1820 , and it can be unknown or imperceptible to base station  1820 . Such procedures and functionalities can be known and practiced in the art. In certain embodiments, measurements can involve proprietary UE signaling facilitating host computer  1810 &#39;s measurements of throughput, propagation times, latency and the like. The measurements can be implemented in that software  1811  and  1831  causes messages to be transmitted, in particular empty or ‘dummy’ messages, using OTT connection  1850  while it monitors propagation times, errors etc. 
       FIG.  19    is a flowchart illustrating an exemplary method and/or procedure implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which, in some exemplary embodiments, can be those described with reference to  FIGS.  17  and  18   . For simplicity of the present disclosure, only drawing references to  FIG.  19    will be included in this section. In step  1910 , the host computer provides user data. In substep  1911  (which can be optional) of step  1910 , the host computer provides the user data by executing a host application. In step  1920 , the host computer initiates a transmission carrying the user data to the UE. In step  1930  (which can be optional), 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 step  1940  (which can also be optional), the UE executes a client application associated with the host application executed by the host computer. 
       FIG.  20    is a flowchart illustrating an exemplary method and/or procedure implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which can be those described with reference to  FIGS.  17  and  18   . For simplicity of the present disclosure, only drawing references to  FIG.  20    will be included in this section. In step  2010  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 step  2020 , the host computer initiates a transmission carrying the user data to the UE. The transmission can pass via the base station, in accordance with the teachings of the embodiments described throughout this disclosure. In step  2030  (which can be optional), the UE receives the user data carried in the transmission. 
       FIG.  21    is a flowchart illustrating an exemplary method and/or procedure implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which can be those described with reference to  FIGS.  17  and  18   . For simplicity of the present disclosure, only drawing references to  FIG.  21    will be included in this section. In step  2110  (which can be optional), the UE receives input data provided by the host computer. Additionally or alternatively, in step  2120 , the UE provides user data. In substep  2121  (which can be optional) of step  2120 , the UE provides the user data by executing a client application. In substep  2111  (which can be optional) of step  2110 , 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 can further consider user input received from the user. Regardless of the specific manner in which the user data was provided, the UE initiates, in substep  2130  (which can be optional), transmission of the user data to the host computer. In step  2140  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. 
       FIG.  22    is a flowchart illustrating an exemplary method and/or procedure implemented in a communication system, in accordance with one embodiment. The communication system includes a host computer, a base station and a UE which can be those described with reference to  FIGS.  17  and  18   . For simplicity of the present disclosure, only drawing references to  FIG.  22    will be included in this section. In step  2210  (which can be optional), in accordance with the teachings of the embodiments described throughout this disclosure, the base station receives user data from the UE. In step  2220  (which can be optional), the base station initiates transmission of the received user data to the host computer. In step  2230  (which can be optional), the host computer receives the user data carried in the transmission initiated by the base station. 
     Any appropriate steps, methods, features, functions, or benefits disclosed herein may be performed through one or more functional units or modules of one or more virtual apparatuses. Each virtual apparatus may comprise a number of these functional units. These functional units may be implemented via processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include digital signal processors (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as read-only memory (ROM), random-access memory (RAM), cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and/or data communications protocols as well as instructions for carrying out one or more of the techniques described herein. In some implementations, the processing circuitry may be used to cause the respective functional unit to perform corresponding functions according one or more embodiments of the present disclosure. 
       FIG.  23    illustrates a schematic block diagram of an apparatus  2300  in a wireless network (for example, the wireless network shown in  FIG.  14   ). The apparatus may be implemented in a wireless device or network node (e.g., wireless device  1410  or network node  1460  shown in  FIG.  14   ). Apparatus  2030  is operable to carry out the example method described with reference to  FIG.  12    and possibly any other processes or methods disclosed herein. It is also to be understood that the method of  FIG.  12    is not necessarily carried out solely by apparatus  2300 . At least some operations of the method can be performed by one or more other entities. 
     Virtual Apparatus  2300  may comprise processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include digital signal processors (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as read-only memory (ROM), random-access memory, cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and/or data communications protocols as well as instructions for carrying out one or more of the techniques described herein, in several embodiments. In some implementations, the processing circuitry may be used to cause receiving unit  2302 , and delaying unit  2304 , and any other suitable units of apparatus  2300  to perform corresponding functions according one or more embodiments of the present disclosure. 
     As illustrated in  FIG.  23   , apparatus  2300  includes receiving unit  2302 , and delaying unit  2304 . The receiving unit  2302  is configured to receive configuration information from a network node defining a SDU discard timer value. The delaying unit  2304  is configured to delay discarding a transmitted PDU until the SDU discard timer has expired, even if the transmitted PDU packet is acknowledged by a lower protocol layer. 
       FIG.  24    illustrates a schematic block diagram of an apparatus  2400  in a wireless network (for example, the wireless network shown in  FIG.  14   ). The apparatus may be implemented in a wireless device or network node (e.g., wireless device  1410  or network node  1460  shown in  FIG.  141   ). Apparatus  2400  is operable to carry out the example method described with reference to  FIG.  131    and possibly any other processes or methods disclosed herein. It is also to be understood that the method of  FIG.  13    is not necessarily carried out solely by apparatus  2400 . At least some operations of the method can be performed by one or more other entities. 
     Virtual Apparatus  2400  may comprise processing circuitry, which may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include digital signal processors (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as read-only memory (ROM), random-access memory, cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory includes program instructions for executing one or more telecommunications and/or data communications protocols as well as instructions for carrying out one or more of the techniques described herein, in several embodiments. In some implementations, the processing circuitry may be used to cause determining unit  2402 , configuring unit  2404 , and any other suitable units of apparatus  2400  to perform corresponding functions according one or more embodiments of the present disclosure. 
     As illustrated in  FIG.  24   , apparatus  2400  includes determining unit  2402 , and configuring unit  2404 . The determining unit  2402  is configured to determine whether a wireless device is connecting to the network via an IAB node. The configuring unit  2404  operates such that, if it is determined that the wireless device is not connecting to the network via an IAB node, the network node configures the wireless device with a first PDCP SDU discard timer, and, if it is determined that the wireless device is connecting to the network via an IAB node, the network node configures the wireless device with a second PDCP SDU discard timer that is longer than the first PDCP SDU discard timer. 
     The term unit may have conventional meaning in the field of electronics, electrical devices and/or electronic devices and may include, for example, electrical and/or electronic circuitry, devices, modules, processors, memories, logic solid state and/or discrete devices, computer programs or instructions for carrying out respective tasks, procedures, computations, outputs, and/or displaying functions, and so on, as such as those that are described herein. 
     Abbreviations 
     At least some of the following abbreviations may be used in this disclosure. If there is an inconsistency between abbreviations, preference should be given to how it is used above. If listed multiple times below, the first listing should be preferred over any subsequent listing(s).
     1×RTT CDMA2000 1×Radio Transmission Technology   3GPP 3rd Generation Partnership Project   5G 5th Generation   ABS Almost Blank Subframe   ARQ Automatic Repeat Request   AWGN Additive White Gaussian Noise   BCCH Broadcast Control Channel   BCH Broadcast Channel   CA Carrier Aggregation   CC Carrier Component   CCCH SDU Common Control Channel SDU   CDMA Code Division Multiplexing Access   CGI Cell Global Identifier   CIR Channel Impulse Response   CP Cyclic Prefix   CPICH Common Pilot Channel   CPICH Ec/No CPICH Received energy per chip divided by the power density in the band   CQI Channel Quality information   C-RNTI Cell RNTI   CSI Channel State Information   CU Centralized Unit   DCCH Dedicated Control Channel   DL Downlink   DM Demodulation   DMRS Demodulation Reference Signal   DRX Discontinuous Reception   DTX Discontinuous Transmission   DTCH Dedicated Traffic Channel   DU Distributed Unit   DUT Device Under Test   E-CID Enhanced Cell-ID (positioning method)   E-SMLC Evolved-Serving Mobile Location Centre   ECGI Evolved CGI   eNB E-UTRAN NodeB   ePDCCH enhanced Physical Downlink Control Channel   E-SMLC evolved Serving Mobile Location Center   E-UTRA Evolved UTRA   E-UTRAN Evolved UTRAN   FDD Frequency Division Duplex   FFS For Further Study   GERAN GSM EDGE Radio Access Network   gNB Base station in NR   GNSS Global Navigation Satellite System   GSM Global System for Mobile communication   HARQ Hybrid Automatic Repeat Request   HO Handover   HSPA High Speed Packet Access   HRPD High Rate Packet Data   IAB Integrated Access Backhaul   IUA Instant Uplink Access   LOS Line of Sight   LPP LTE Positioning Protocol   LTE Long-Term Evolution   MAC Medium Access Control   MBMS Multimedia Broadcast Multicast Services   MBSFN Multimedia Broadcast multicast service Single Frequency Network   MBSFN ABS MBSFN Almost Blank Subframe   MDT Minimization of Drive Tests   MIB Master Information Block   MME Mobility Management Entity   MSC Mobile Switching Center   NPDCCH Narrowband Physical Downlink Control Channel   NR New Radio   OCNG OFDMA Channel Noise Generator   OFDM Orthogonal Frequency Division Multiplexing   OFDMA Orthogonal Frequency Division Multiple Access   OSS Operations Support System   OTDOA Observed Time Difference of Arrival   O&amp;M Operation and Maintenance   PBCH Physical Broadcast Channel   P-CCPCH Primary Common Control Physical Channel   PCell Primary Cell   PCFICH Physical Control Format Indicator Channel   PDCCH Physical Downlink Control Channel   PDP Profile Delay Profile   PDSCH Physical Downlink Shared Channel   PDU Protocol Data Unit   PGW Packet Gateway   PHICH Physical Hybrid-ARQ Indicator Channel   PLMN Public Land Mobile Network   PMI Precoder Matrix Indicator   PRACH Physical Random Access Channel   PRS Positioning Reference Signal   PSS Primary Synchronization Signal   PUCCH Physical Uplink Control Channel   PUSCH Physical Uplink Shared Channel   RACH Random Access Channel   QAM Quadrature Amplitude Modulation   RAN Radio Access Network   RAT Radio Access Technology   RLM Radio Link Management   RNC Radio Network Controller   RNTI Radio Network Temporary Identifier   RRC Radio Resource Control   RRM Radio Resource Management   RS Reference Signal   RSCP Received Signal Code Power   RSRP Reference Symbol Received Power OR Reference Signal Received Power   RSRQ Reference Signal Received Quality OR Reference Symbol Received Quality   RSSI Received Signal Strength Indicator   RSTD Reference Signal Time Difference   SCH Synchronization Channel   SCell Secondary Cell   SDU Service Data Unit   SFN System Frame Number   SGW Serving Gateway   SI System Information   SIB System Information Block   SNR Signal to Noise Ratio   SON Self Optimized Network   SS Synchronization Signal   SSS Secondary Synchronization Signal   TDD Time Division Duplex   TDOA Time Difference of Arrival   TOA Time of Arrival   TSS Tertiary Synchronization Signal   TTI Transmission Time Interval   UE User Equipment   UL Uplink   UMTS Universal Mobile Telecommunication System   USIM Universal Subscriber Identity Module   UTDOA Uplink Time Difference of Arrival   UTRA Universal Terrestrial Radio Access   UTRAN Universal Terrestrial Radio Access Network   WCDMA Wide CDMA   WLAN Wide Local Area Network