Method, apparatus and computer program relating to providing feedback about data units

Abstract

Transmission of data units may involve the use of data unit numbers to track the reception of the data units at a receiving entity. A receiving entity may provide feedback to the transmitting entity about the progress of transmission of the data units using the data unit numbers. A receiving unit may, in response to determining one or more data unit number values meet one or more conditions (e.g. data unit number value for an unreceived data unit comprise the expiry of a timer) while yet to receive from a transmitting entity one or more data units having the data unit number values, make a determination not to wait to receive the data units having the data unit number values. The receiving entity sends a status report to the transmitting entity, wherein the status report indicates the reception of the data units having the data unit number values is no longer waited for. The transmitting entity, in response to receiving the status report indicating the data units are no longer waited for, adjusts the transmitting window based on at least the one or more first data unit number values of the status report.

Description

TECHNICAL FIELD Various example embodiments of this disclosure relate to a method, apparatus and computer program and in particular but not exclusively to providing feedback about data units. BACKGROUND Transmission of data units may involve the use of data unit numbers to track the reception of the data units at a receiving entity. A receiving entity may provide feedback to the transmitting entity about the progress of transmission of the data units using the data unit numbers. SUMMARY Some example embodiments of this disclosure will be described with respect to certain aspects. These aspects are not intended to indicate key or essential features of the embodiments of this disclosure, nor are they intended to be used to limit the scope of thereof. Other features, aspects, and elements will be readily apparent to a person skilled in the art in view of this disclosure. Apparatus comprising means for: in response to determining that one or more data unit number values meet one or more conditions while yet to receive from a transmitting entity one or more data units having the one or more data unit number values, making a determination not to wait to receive the one or more data units having the one or more data unit number values; and sending a status report to the transmitting entity, wherein the status report indicates that reception of the one or more data units having the one or more data unit number values is no longer waited for. The apparatus may comprise means for progressing a reception window past one or more of the data unit number values for which a determination not to wait to receive a data unit has been made. The one or more conditions for a data unit number value for an unreceived data unit may comprise the expiry of a timer associated with the data unit number value for the unreceived data unit. The timer associated with the data unit number value for the unreceived data unit may be started in response to receiving a data unit having a data unit number value higher than the data unit number value of the unreceived data unit. The timer may be started in response to requesting re-transmission of the data unit a predetermined number of times. The one or more conditions for a data unit number value for an unreceived data unit may comprise reception from the transmitting entity of an indication not to wait for the unreceived data unit. The one or more data units may be one or more radio link control layer data units carrying one or more packet data convergence protocol layer data units. The apparatus may be an access node and the transmitting entity may be a user equipment. The apparatus may be a user equipment and the transmitting entity may be an access node. Apparatus comprising means for: receiving a status report from a receiving entity, wherein the status report indicates that the receiving entity is no longer waiting to receive one or more data units having one or more first data unit number values for which the receiving entity has not received one or more data units; and adjusting a position of a transmitting window based on at least the one or more first data unit number values of the status report. The one or more data units may be one or more first layer data units carrying one or more second layer data units, and the apparatus may comprise means for: delivering from the first layer to the second layer an indication that the receiving entity has not received and is no longer waiting to receive the one or more second layer data units. The one or more data units may be one or more radio link control layer data units carrying one or more packet data convergence protocol layer data units. The apparatus may be an access node and the receiving entity may be a user equipment. The apparatus may be a user equipment and the receiving entity may be an access node. Apparatus comprising means for: in response to determining that one or more data unit number values meet one or more conditions while yet to receive from a transmitting entity one or more data units having the one or more data unit number values, making a determination not to wait to receive the one or more data units having the one or more data unit number values; sending to a transmitting entity a first layer status report, wherein the status report distinguishes at least between (i) one or more data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value; and (ii) one or more data unit number values for which no data unit has been received and for which there has been no determination not to wait to receive a data unit having the data unit number value. The apparatus may comprise means for sending to the transmitting entity an indication of a position of a second layer receiving window. One or more data units within the second layer receiving window may have been received, and the indication may be sent without a bitmap field indicating second layer data unit number values for the one or more received data units. The indication may be included in a second layer status report indicating one or more second layer data unit number values of one or more received second layer data units. The indication may be included in the header of a second layer data unit. Sending of the indication may be triggered periodically with respect to advancement of the second layer receiving window. The first layer status report may indicate a range of first layer data unit number values, and may specify one or more data unit number values within the range for which a data unit is waited; wherein a remainder of the first layer data unit number values within the range are data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit. The apparatus may comprise means for progressing a first layer receiving window past one or more of the data unit number values for which a determination not to wait to receive a data unit has been made. The one or more conditions for a data unit number value for an unreceived data unit may comprise the expiry of a timer associated with the data unit number value for the unreceived data unit. The timer associated with the data unit number value for the unreceived data unit may be started in response to receiving a data unit having a data unit number value higher than the data unit number value of the unreceived data unit. The timer may be started in response to requesting re-transmission of the data unit a predetermined number of times. The one or more conditions for a data unit number value for an unreceived data unit may comprise reception from the transmitting entity of an indication not to wait for the unreceived data unit. The first layer may be a radio link control layer. The second layer may be a packet data convergence protocol layer. The apparatus may be an access node and the transmitting entity may be a user equipment. The apparatus may be a user equipment and the transmitting entity may be an access node. Apparatus comprising means for: receiving from a receiving entity a first layer status report distinguishing at least between (i) one or more first data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value; and (ii) one or more second data unit number values for which no data unit has been received at the receiving entity and for which there has been no determination not to wait to receive a data unit having the data unit number value; and adjusting a position of a first layer transmitting window based on the one or more first data unit number values of the first layer status report. The apparatus may comprise means for: receiving from the receiving entity an indication of a position of a second layer receiving window; and adjusting a position of a second layer transmitting window based on the indication. The apparatus may comprise a first layer entity and a second layer entity, and the apparatus may comprise means for: delivering from the first layer entity to the second layer entity an interlayer status report based on the first layer status report. The apparatus may comprise a control plane entity; and the apparatus may comprise means for: sending from the control plane entity to the second layer entity an indication that the interlayer status report does not distinguish a between (a) data unit number values that are a data unit number value of a received data unit, and (b) data unit number values for which a data unit has not been received and a determination has been made not to wait to receive a data unit. The first layer may be a radio link control layer. The second layer may be a packet data convergence protocol layer. The apparatus may be an access node and the receiving entity may be a user equipment. The apparatus may be a user equipment and the receiving entity may be an access node. Apparatus comprising means for: sending a status report to a transmitting entity, wherein the status report distinguishes at least between (i) one or more data unit number values for which a data unit has been received, and (ii) one or more data unit number values for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value. The apparatus may comprise means for: progressing a reception window past one or more of the data unit number values for which a determination not to wait to receive a data unit has been made. The determination not to wait to receive an unreceived data unit may be made in response to the data unit number value for the data unit meeting one or more conditions. The one or more conditions for a data unit number value for an unreceived data unit may comprise the expiry of a timer associated with the data unit number value for the unreceived data unit. The timer associated with the data unit number value for the unreceived data unit may be started in response to receiving a data unit having a data unit number value higher than the data unit number value of the unreceived data unit. The timer may be started in response to requesting re-transmission of the data unit a predetermined number of times. The one or more conditions for a data unit number value for an unreceived data unit may comprise reception from the transmitting entity of an indication not to wait for the unreceived data unit. The status report may be a radio link control layer status report. The apparatus may be an access node and the transmitting entity may be a user equipment. The apparatus may be a user equipment and the transmitting entity may be an access node. Apparatus comprising means for: receiving a first layer status report from a receiving entity, wherein the first layer status report distinguishes at least between (i) one or more first data unit number values for which a data unit has been received at the receiving entity, and (ii) one or more second data unit number values for which a data unit has not been received and for which a determination has been made not to wait to receive a data unit; and adjusting a position of first layer transmitting window based at least partly on the first and second data unit number values of the first layer status report. The apparatus may comprise means for: adjusting a position of a second layer transmitting window also based at least partly on the first and second data unit number values of the first layer status report. The apparatus may comprise a first layer entity and a second layer entity; and the apparatus may comprise means for: sending from the first layer entity to the second layer entity an interlayer status report indicating one or more second layer data unit number values corresponding to the one or more first data unit number values, and one or more second layer data unit number values corresponding to the one or more second data unit number values. The apparatus may comprise means for: adjusting the position of a second layer transmitting window based on (a) the one or more second layer data unit number values corresponding to the one or more first data unit number values and (b) the one or more second layer data unit number values corresponding to the one or more second data unit number values, and one or more assumptions about adjustment of a second layer receiving window at the receiving entity. Adjusting the second layer transmitting window based on one or more assumptions about adjustment of the second layer receiving window at the receiving entity may comprise: progressing the second layer transmitting window past the one or more second layer data unit number values corresponding to the one or more second data unit number values in response to expiry of one or more timers started upon submission to the first layer entity of the second layer data units having the one or more second layer data unit number values corresponding to the one or more second data unit number values. The apparatus may comprise means for: using the one or more second layer data unit number values corresponding to the one or more first data unit number values, and the one or more second layer data unit number values corresponding to the one or more second data unit number values to identify one or more second layer data units for re-transmission. The apparatus may comprise a plurality of first layer entities and the apparatus may comprises means for: using the one or more second layer data unit number values corresponding to the one or more first data unit number values, and the one or more second layer data unit number values corresponding to the one or more second data unit number values to identify one or more second layer data units for which to send an interlayer discard indication from the second layer entity to one or more of the plurality of first layer entities. The status report may be a radio link control layer status report. The second layer may be a packet data convergence protocol layer. The apparatus may comprise a control plane entity; and the apparatus may comprise means for: sending from the control plane entity to the second layer entity an indication that the interlayer status report distinguishes between (a) data unit number values that are a data unit number value of a received data unit, and (b) data unit number values for which a data unit has not been received and a determination has been made not to wait to receive a data unit. A method comprising: in response to determining that one or more data unit number values meet one or more conditions while yet to receive from a transmitting entity one or more data units having the one or more data unit number values, making a determination not to wait to receive the one or more data units having the one or more data unit number values; and sending a status report to the transmitting entity, wherein the status report indicates that reception of the one or more data units having the one or more data unit number values is no longer waited for. The method may comprise progressing a reception window past one or more of the data unit number values for which a determination not to wait to receive a data unit has been made. The one or more conditions for a data unit number value for an unreceived data unit may comprise the expiry of a timer associated with the data unit number value for the unreceived data unit. The timer associated with the data unit number value for the unreceived data unit may be started in response to receiving a data unit having a data unit number value higher than the data unit number value of the unreceived data unit. The timer may be started in response to requesting re-transmission of the data unit a predetermined number of times. The one or more conditions for a data unit number value for an unreceived data unit may comprise reception from the transmitting entity of an indication not to wait for the unreceived data unit. The one or more data units may be one or more radio link control layer data units carrying one or more packet data convergence protocol layer data units. The method may be performed at an access node and the transmitting entity may be a user equipment. The method may be performed at a user equipment and the transmitting entity may be an access node. A method comprising: receiving a status report from a receiving entity, wherein the status report indicates that the receiving entity is no longer waiting to receive one or more data units having one or more first data unit number values for which the receiving entity has not received one or more data units; and adjusting a position of a transmitting window based on at least the one or more first data unit number values of the status report. The one or more data units may be one or more first layer data units carrying one or more second layer data units, and the method may comprise: delivering from the first layer to the second layer an indication that the receiving entity has not received and is no longer waiting to receive the one or more second layer data units. The one or more data units may be one or more radio link control layer data units carrying one or more packet data convergence protocol layer data units. The method may be performed at an access node and the receiving entity may be a user equipment. The method may be performed at a user equipment and the receiving entity may be an access node. A method comprising: in response to determining that one or more data unit number values meet one or more conditions while yet to receive from a transmitting entity one or more data units having the one or more data unit number values, making a determination not to wait to receive the one or more data units having the one or more data unit number values; and sending to a transmitting entity a first layer status report, wherein the status report distinguishes at least between (i) one or more data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value; and (ii) one or more data unit number values for which no data unit has been received and for which there has been no determination not to wait to receive a data unit having the data unit number value. The method may comprise sending to the transmitting entity an indication of a position of a second layer receiving window. One or more data units within the second layer receiving window may have been received, and the indication may be sent without a bitmap field indicating second layer data unit number values for the one or more received data units. The indication may be included in a second layer status report indicating one or more second layer data unit number values of one or more received second layer data units. The indication may be included in the header of a second layer data unit. Sending of the indication may be triggered periodically with respect to advancement of the second layer receiving window. The first layer status report may indicate a range of first layer data unit number values, and may specify one or more data unit number values within the range for which a data unit is waited; wherein a remainder of the first layer data unit number values within the range are data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit. The method may comprise progressing a first layer receiving window past one or more of the data unit number values for which a determination not to wait to receive a data unit has been made. The one or more conditions for a data unit number value for an unreceived data unit may comprise the expiry of a timer associated with the data unit number value for the unreceived data unit. The timer associated with the data unit number value for the unreceived data unit may be started in response to receiving a data unit having a data unit number value higher than the data unit number value of the unreceived data unit. The timer may be started in response to requesting re-transmission of the data unit a predetermined number of times. The one or more conditions for a data unit number value for an unreceived data unit may comprise reception from the transmitting entity of an indication not to wait for the unreceived data unit. The first layer may be a radio link control layer. The second layer may be a packet data convergence protocol layer. The method may be performed at an access node and the transmitting entity may be a user equipment. The method may be performed at a user equipment and the transmitting entity may be an access node. A method comprising: receiving from a receiving entity a first layer status report distinguishing at least between (i) one or more first data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value; and (ii) one or more second data unit number values for which no data unit has been received at the receiving entity and for which there has been no determination not to wait to receive a data unit having the data unit number value; and adjusting a position of a first layer transmitting window based on the one or more first data unit number values of the first layer status report. The method may comprise: receiving from the receiving entity an indication of a position of a second layer receiving window; and adjusting a position of a second layer transmitting window based on the indication. The method may comprise: delivering from a first layer entity to a second layer entity an interlayer status report based on the first layer status report. The method may comprise a control plane entity; and the method may comprise: sending from the control plane entity to the second layer entity an indication that the interlayer status report does not distinguish a between (a) data unit number values that are a data unit number value of a received data unit, and (b) data unit number values for which a data unit has not been received and a determination has been made not to wait to receive a data unit. The first layer may be a radio link control layer. The second layer may be a packet data convergence protocol layer. The method may be performed at an access node and the receiving entity may be a user equipment. The method may be performed at a user equipment and the receiving entity may be an access node. A method comprising: sending a status report to a transmitting entity, wherein the status report distinguishes at least between (i) one or more data unit number values for which a data unit has been received, and (ii) one or more data unit number values for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value. The method may comprise: progressing a reception window past one or more of the data unit number values for which a determination not to wait to receive a data unit has been made. The determination not to wait to receive an unreceived data unit may be made in response to the data unit number value for the data unit meeting one or more conditions. The one or more conditions for a data unit number value for an unreceived data unit may comprise the expiry of a timer associated with the data unit number value for the unreceived data unit. The timer associated with the data unit number value for the unreceived data unit may be started in response to receiving a data unit having a data unit number value higher than the data unit number value of the unreceived data unit. The timer may be started in response to requesting re-transmission of the data unit a predetermined number of times. The one or more conditions for a data unit number value for an unreceived data unit may comprise reception from the transmitting entity of an indication not to wait for the unreceived data unit. The status report may be a radio link control layer status report. The method may be performed at an access node and the transmitting entity may be a user equipment. The method may be performed at a user equipment and the transmitting entity may be an access node. A method comprising: receiving a first layer status report from a receiving entity, wherein the first layer status report distinguishes at least between (i) one or more first data unit number values for which a data unit has been received at the receiving entity, and (ii) one or more second data unit number values for which a data unit has not been received and for which a determination has been made not to wait to receive a data unit; and adjusting a position of first layer transmitting window based at least partly on the first and second data unit number values of the first layer status report. The method may comprise: adjusting a position of a second layer transmitting window also based at least partly on the first and second data unit number values of the first layer status report. The method may comprise: sending from a first layer entity to a second layer entity an interlayer status report indicating one or more second layer data unit number values corresponding to the one or more first data unit number values, and one or more second layer data unit number values corresponding to the one or more second data unit number values. The method may comprise: adjusting the position of a second layer transmitting window based on (a) the one or more second layer data unit number values corresponding to the one or more first data unit number values and (b) the one or more second layer data unit number values corresponding to the one or more second data unit number values, and one or more assumptions about adjustment of a second layer receiving window at the receiving entity. Adjusting the second layer transmitting window based on one or more assumptions about adjustment of the second layer receiving window at the receiving entity may comprise: progressing the second layer transmitting window past the one or more second layer data unit number values corresponding to the one or more second data unit number values in response to expiry of one or more timers started upon submission to the first layer entity of the second layer data units having the one or more second layer data unit number values corresponding to the one or more second data unit number values. The method may comprise means for: using the one or more second layer data unit number values corresponding to the one or more first data unit number values, and the one or more second layer data unit number values corresponding to the one or more second data unit number values to identify one or more second layer data units for re-transmission. The method may comprise: using the one or more second layer data unit number values corresponding to the one or more first data unit number values, and the one or more second layer data unit number values corresponding to the one or more second data unit number values to identify one or more second layer data units for which to send an interlayer discard indication from a second layer entity to one or more of a plurality of first layer entities. The status report may be a radio link control layer status report. The second layer may be a packet data convergence protocol layer. The method may comprise: sending from a control plane entity to the second layer entity an indication that the interlayer status report distinguishes between (a) data unit number values that are a data unit number value of a received data unit, and (b) data unit number values for which a data unit has not been received and a determination has been made not to wait to receive a data unit. Apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: in response to determining that one or more data unit number values meet one or more conditions while yet to receive from a transmitting entity one or more data units having the one or more data unit number values, making a determination not to wait to receive the one or more data units having the one or more data unit number values; and sending a status report to the transmitting entity, wherein the status report indicates that reception of the one or more data units having the one or more data unit number values is no longer waited for. The at least one memory and computer program code may be configured to, with the at least one processor, cause the apparatus to progress a reception window past one or more of the data unit number values for which a determination not to wait to receive a data unit has been made. The one or more conditions for a data unit number value for an unreceived data unit may comprise the expiry of a timer associated with the data unit number value for the unreceived data unit. The timer associated with the data unit number value for the unreceived data unit may be started in response to receiving a data unit having a data unit number value higher than the data unit number value of the unreceived data unit. The timer may be started in response to requesting re-transmission of the data unit a predetermined number of times. The one or more conditions for a data unit number value for an unreceived data unit may comprise reception from the transmitting entity of an indication not to wait for the unreceived data unit. The one or more data units may be one or more radio link control layer data units carrying one or more packet data convergence protocol layer data units. The apparatus may be an access node and the transmitting entity may be a user equipment. The apparatus may be a user equipment and the transmitting entity may be an access node. Apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: receiving a status report from a receiving entity, wherein the status report indicates that the receiving entity is no longer waiting to receive one or more data units having one or more first data unit number values for which the receiving entity has not received one or more data units; and adjusting a position of a transmitting window based on at least the one or more first data unit number values of the status report. The one or more data units may be one or more first layer data units carrying one or more second layer data units, and the apparatus may comprise means for: delivering from the first layer to the second layer an indication that the receiving entity has not received and is no longer waiting to receive the one or more second layer data units. The one or more data units may be one or more radio link control layer data units carrying one or more packet data convergence protocol layer data units. The apparatus may be an access node and the receiving entity may be a user equipment. The apparatus may be a user equipment and the receiving entity may be an access node. Apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: in response to determining that one or more data unit number values meet one or more conditions while yet to receive from a transmitting entity one or more data units having the one or more data unit number values, making a determination not to wait to receive the one or more data units having the one or more data unit number values; sending to a transmitting entity a first layer status report, wherein the status report distinguishes at least between (i) one or more data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value; and (ii) one or more data unit number values for which no data unit has been received and for which there has been no determination not to wait to receive a data unit having the data unit number value. The at least one memory and computer program code may be configured to, with the at least one processor, cause the apparatus to send to the transmitting entity an indication of a position of a second layer receiving window. One or more data units within the second layer receiving window may have been received, and the indication may be sent without a bitmap field indicating second layer data unit number values for the one or more received data units. The indication may be included in a second layer status report indicating one or more second layer data unit number values of one or more received second layer data units. The indication may be included in the header of a second layer data unit. Sending of the indication may be triggered periodically with respect to advancement of the second layer receiving window. The first layer status report may indicate a range of first layer data unit number values, and may specify one or more data unit number values within the range for which a data unit is waited; wherein a remainder of the first layer data unit number values within the range are data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit. The at least one memory and computer program code may be configured to, with the at least one processor, cause the apparatus to progress a first layer receiving window past one or more of the data unit number values for which a determination not to wait to receive a data unit has been made. The one or more conditions for a data unit number value for an unreceived data unit may comprise the expiry of a timer associated with the data unit number value for the unreceived data unit. The timer associated with the data unit number value for the unreceived data unit may be started in response to receiving a data unit having a data unit number value higher than the data unit number value of the unreceived data unit. The timer may be started in response to requesting re-transmission of the data unit a predetermined number of times. The one or more conditions for a data unit number value for an unreceived data unit may comprise reception from the transmitting entity of an indication not to wait for the unreceived data unit. The first layer may be a radio link control layer. The second layer may be a packet data convergence protocol layer. The apparatus may be an access node and the transmitting entity may be a user equipment. The apparatus may be a user equipment and the transmitting entity may be an access node. Apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: receiving from a receiving entity a first layer status report distinguishing at least between (i) one or more first data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value; and (ii) one or more second data unit number values for which no data unit has been received at the receiving entity and for which there has been no determination not to wait to receive a data unit having the data unit number value; and adjusting a position of a first layer transmitting window based on the one or more first data unit number values of the first layer status report. The at least one memory and computer program code may be configured to, with the at least one processor, cause the apparatus to: receive from the receiving entity an indication of a position of a second layer receiving window; and adjust a position of a second layer transmitting window based on the indication. The apparatus may comprise a first layer entity and a second layer entity, and the at least one memory and computer program code may be configured to, with the at least one processor, cause the apparatus to: deliver from the first layer entity to the second layer entity an interlayer status report based on the first layer status report. The apparatus may comprise a control plane entity; and the at least one memory and computer program code may be configured to, with the at least one processor, cause the apparatus to send from the control plane entity to the second layer entity an indication that the interlayer status report does not distinguish a between (a) data unit number values that are a data unit number value of a received data unit, and (b) data unit number values for which a data unit has not been received and a determination has been made not to wait to receive a data unit. The first layer may be a radio link control layer. The second layer may be a packet data convergence protocol layer. The apparatus may be an access node and the receiving entity may be a user equipment. The apparatus may be a user equipment and the receiving entity may be an access node. Apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: sending a status report to a transmitting entity, wherein the status report distinguishes at least between (i) one or more data unit number values for which a data unit has been received, and (ii) one or more data unit number values for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value. The at least one memory and computer program code may be configured to, with the at least one processor, cause the apparatus to progress a reception window past one or more of the data unit number values for which a determination not to wait to receive a data unit has been made. The determination not to wait to receive an unreceived data unit may be made in response to the data unit number value for the data unit meeting one or more conditions. The one or more conditions for a data unit number value for an unreceived data unit may comprise the expiry of a timer associated with the data unit number value for the unreceived data unit. The timer associated with the data unit number value for the unreceived data unit may be started in response to receiving a data unit having a data unit number value higher than the data unit number value of the unreceived data unit. The timer may be started in response to requesting re-transmission of the data unit a predetermined number of times. The one or more conditions for a data unit number value for an unreceived data unit may comprise reception from the transmitting entity of an indication not to wait for the unreceived data unit. The status report may be a radio link control layer status report. The apparatus may be an access node and the transmitting entity may be a user equipment. The apparatus may be a user equipment and the transmitting entity may be an access node. Apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus to perform: receiving a first layer status report from a receiving entity, wherein the first layer status report distinguishes at least between (I) one or more first data unit number values for which a data unit has been received at the receiving entity, and (ii) one or more second data unit number values for which a data unit has not been received and for which a determination has been made not to wait to receive a data unit; and adjusting a position of first layer transmitting window based at least partly on the first and second data unit number values of the first layer status report. The at least one memory and computer program code may be configured to, with the at least one processor, cause the apparatus to adjust a position of a second layer transmitting window also based at least partly on the first and second data unit number values of the first layer status report. The apparatus may comprise a first layer entity and a second layer entity; and the at least one memory and computer program code may be configured to, with the at least one processor, cause the apparatus to: send from the first layer entity to the second layer entity an inter-layer status report indicating one or more second layer data unit number values corresponding to the one or more first data unit number values, and one or more second layer data unit number values corresponding to the one or more second data unit number values. The at least one memory and computer program code may be configured to, with the at least one processor, cause the apparatus to: adjust the position of a second layer transmitting window based on (a) the one or more second layer data unit number values corresponding to the one or more first data unit number values and (b) the one or more second layer data unit number values corresponding to the one or more second data unit number values, and one or more assumptions about adjustment of a second layer receiving window at the receiving entity. Adjusting the second layer transmitting window based on one or more assumptions about adjustment of the second layer receiving window at the receiving entity may comprise: progressing the second layer transmitting window past the one or more second layer data unit number values corresponding to the one or more second data unit number values in response to expiry of one or more timers started upon submission to the first layer entity of the second layer data units having the one or more second layer data unit number values corresponding to the one or more second data unit number values. The at least one memory and computer program code may be configured to, with the at least one processor, cause the apparatus to: use the one or more second layer data unit number values corresponding to the one or more first data unit number values, and the one or more second layer data unit number values corresponding to the one or more second data unit number values to identify one or more second layer data units for re-transmission. The apparatus may comprise a plurality of first layer entities and the at least one memory and computer program code may be configured to, with the at least one processor, cause the apparatus to: use the one or more second layer data unit number values corresponding to the one or more first data unit number values, and the one or more second layer data unit number values corresponding to the one or more second data unit number values to identify one or more second layer data units for which to send an interlayer discard indication from the second layer entity to one or more of the plurality of first layer entities. The status report may be a radio link control layer status report. The second layer may be a packet data convergence protocol layer. The apparatus may comprise a control plane entity; and the at least one memory and computer program code may be configured to, with the at least one processor, cause the apparatus to: send from the control plane entity to the second layer entity an indication that the interlayer status report distinguishes between (a) data unit number values that are a data unit number value of a received data unit, and (b) data unit number values for which a data unit has not been received and a determination has been made not to wait to receive a data unit. Apparatus comprising: determination making circuitry for, in response to determining that one or more data unit number values meet one or more conditions while yet to receive from a transmitting entity one or more data units having the one or more data unit number values, making a determination not to wait to receive the one or more data units having the one or more data unit number values; and sending circuitry for sending a status report to the transmitting entity, wherein the status report indicates that reception of the one or more data units having the one or more data unit number values is no longer waited for. Apparatus comprising: receiving circuitry for receiving a status report from a receiving entity, wherein the status report indicates that the receiving entity is no longer waiting to receive one or more data units having one or more first data unit number values for which the receiving entity has not received one or more data units; and adjusting circuitry for adjusting a position of a transmitting window based on at least the one or more first data unit number values of the status report. Apparatus comprising: determination making circuitry for, in response to determining that one or more data unit number values meet one or more conditions while yet to receive from a transmitting entity one or more data units having the one or more data unit number values, making a determination not to wait to receive the one or more data units having the one or more data unit number values; sending circuitry for sending to a transmitting entity a first layer status report, wherein the status report distinguishes at least between (i) one or more data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value; and (ii) one or more data unit number values for which no data unit has been received and for which there has been no determination not to wait to receive a data unit having the data unit number value. Apparatus comprising: receiving circuitry for receiving from a receiving entity a first layer status report distinguishing at least between (i) one or more first data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value; and (ii) one or more second data unit number values for which no data unit has been received at the receiving entity and for which there has been no determination not to wait to receive a data unit having the data unit number value; and adjusting circuitry for adjusting a position of a first layer transmitting window based on the one or more first data unit number values of the first layer status report. Apparatus comprising: sending circuitry for sending a status report to a transmitting entity, wherein the status report distinguishes at least between (i) one or more data unit number values for which a data unit has been received, and (ii) one or more data unit number values for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value. Apparatus comprising: receiving circuitry for receiving a first layer status report from a receiving entity, wherein the first layer status report distinguishes at least between (i) one or more first data unit number values for which a data unit has been received at the receiving entity, and (ii) one or more second data unit number values for which a data unit has not been received and for which a determination has been made not to wait to receive a data unit; and adjusting circuitry for adjusting a position of first layer transmitting window based at least partly on the first and second data unit number values of the first layer status report. A computer readable medium comprising program instructions stored thereon for performing: in response to determining that one or more data unit number values meet one or more conditions while yet to receive from a transmitting entity one or more data units having the one or more data unit number values, making a determination not to wait to receive the one or more data units having the one or more data unit number values; and sending a status report to the transmitting entity, wherein the status report indicates that reception of the one or more data units having the one or more data unit number values is no longer waited for. A computer readable medium comprising program instructions stored thereon for performing: receiving a status report from a receiving entity, wherein the status report indicates that the receiving entity is no longer waiting to receive one or more data units having one or more first data unit number values for which the receiving entity has not received one or more data units; and adjusting a position of a transmitting window based on at least the one or more first data unit number values of the status report. A computer readable medium comprising program instructions stored thereon for performing: in response to determining that one or more data unit number values meet one or more conditions while yet to receive from a transmitting entity one or more data units having the one or more data unit number values, making a determination not to wait to receive the one or more data units having the one or more data unit number values; sending to a transmitting entity a first layer status report, wherein the status report distinguishes at least between (i) one or more data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value; and (ii) one or more data unit number values for which no data unit has been received and for which there has been no determination not to wait to receive a data unit having the data unit number value. A computer readable medium comprising program instructions stored thereon for performing: receiving from a receiving entity a first layer status report distinguishing at least between (i) one or more first data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value; and (ii) one or more second data unit number values for which no data unit has been received at the receiving entity and for which there has been no determination not to wait to receive a data unit having the data unit number value; and adjusting a position of a first layer transmitting window based on the one or more first data unit number values of the first layer status report. A computer readable medium comprising program instructions stored thereon for performing: sending a status report to a transmitting entity, wherein the status report distinguishes at least between (i) one or more data unit number values for which a data unit has been received, and (ii) one or more data unit number values for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value. A computer readable medium comprising program instructions stored thereon for performing: receiving a first layer status report from a receiving entity, wherein the first layer status report distinguishes at least between (i) one or more first data unit number values for which a data unit has been received at the receiving entity, and (ii) one or more second data unit number values for which a data unit has not been received and for which a determination has been made not to wait to receive a data unit; and adjusting a position of first layer transmitting window based at least partly on the first and second data unit number values of the first layer status report. A non-transitory computer readable medium comprising program instructions stored thereon for performing: in response to determining that one or more data unit number values meet one or more conditions while yet to receive from a transmitting entity one or more data units having the one or more data unit number values, making a determination not to wait to receive the one or more data units having the one or more data unit number values; and sending a status report to the transmitting entity, wherein the status report indicates that reception of the one or more data units having the one or more data unit number values is no longer waited for. A non-transitory computer readable medium comprising program instructions stored thereon for performing: receiving a status report from a receiving entity, wherein the status report indicates that the receiving entity is no longer waiting to receive one or more data units having one or more first data unit number values for which the receiving entity has not received one or more data units; and adjusting a position of a transmitting window based on at least the one or more first data unit number values of the status report. A non-transitory computer readable medium comprising program instructions stored thereon for performing: in response to determining that one or more data unit number values meet one or more conditions while yet to receive from a transmitting entity one or more data units having the one or more data unit number values, making a determination not to wait to receive the one or more data units having the one or more data unit number values; sending to a transmitting entity a first layer status report, wherein the status report distinguishes at least between (i) one or more data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value; and (ii) one or more data unit number values for which no data unit has been received and for which there has been no determination not to wait to receive a data unit having the data unit number value. A non-transitory computer readable medium comprising program instructions stored thereon for performing: receiving from a receiving entity a first layer status report distinguishing at least between (i) one or more first data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value; and (ii) one or more second data unit number values for which no data unit has been received at the receiving entity and for which there has been no determination not to wait to receive a data unit having the data unit number value; and adjusting a position of a first layer transmitting window based on the one or more first data unit number values of the first layer status report. A non-transitory computer readable medium comprising program instructions stored thereon for performing: sending a status report to a transmitting entity, wherein the status report distinguishes at least between (i) one or more data unit number values for which a data unit has been received, and (ii) one or more data unit number values for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value. A non-transitory computer readable medium comprising program instructions stored thereon for performing: receiving a first layer status report from a receiving entity, wherein the first layer status report distinguishes at least between (i) one or more first data unit number values for which a data unit has been received at the receiving entity, and (ii) one or more second data unit number values for which a data unit has not been received and for which a determination has been made not to wait to receive a data unit; and adjusting a position of first layer transmitting window based at least partly on the first and second data unit number values of the first layer status report. A computer program comprising computer executable code which when run on at least one processor is configured to cause an apparatus at least to: in response to determining that one or more data unit number values meet one or more conditions while yet to receive from a transmitting entity one or more data units having the one or more data unit number values, make a determination not to wait to receive the one or more data units having the one or more data unit number values; and send a status report to the transmitting entity, wherein the status report indicates that reception of the one or more data units having the one or more data unit number values is no longer waited for. A computer program comprising computer executable code which when run on at least one processor is configured to cause an apparatus at least to: receive a status report from a receiving entity, wherein the status report indicates that the receiving entity is no longer waiting to receive one or more data units having one or more first data unit number values for which the receiving entity has not received one or more data units; and adjust a position of a transmitting window based on at least the one or more first data unit number values of the status report. A computer program comprising computer executable code which when run on at least one processor is configured to cause an apparatus at least to: in response to determining that one or more data unit number values meet one or more conditions while yet to receive from a transmitting entity one or more data units having the one or more data unit number values, make a determination not to wait to receive the one or more data units having the one or more data unit number values; and send to a transmitting entity a first layer status report, wherein the status report distinguishes at least between (i) one or more data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value; and (ii) one or more data unit number values for which no data unit has been received and for which there has been no determination not to wait to receive a data unit having the data unit number value. A computer program comprising computer executable code which when run on at least one processor is configured to cause an apparatus at least to: receive from a receiving entity a first layer status report distinguishing at least between (i) one or more first data unit number values that are either a data unit number value of a received data unit, or a data unit number value for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value; and (ii) one or more second data unit number values for which no data unit has been received at the receiving entity and for which there has been no determination not to wait to receive a data unit having the data unit number value; and adjust a position of a first layer transmitting window based on the one or more first data unit number values of the first layer status report. A computer program comprising computer executable code which when run on at least one processor is configured to cause an apparatus at least to: send a status report to a transmitting entity, wherein the status report distinguishes at least between (i) one or more data unit number values for which a data unit has been received, and (ii) one or more data unit number values for which a data unit has not been received and a determination has been made not to wait to receive a data unit having the data unit number value. A computer program comprising computer executable code which when run on at least one processor is configured to cause an apparatus at least to: receive a first layer status report from a receiving entity, wherein the first layer status report distinguishes at least between (i) one or more first data unit number values for which a data unit has been received at the receiving entity, and (ii) one or more second data unit number values for which a data unit has not been received and for which a determination has been made not to wait to receive a data unit; and adjust a position of first layer transmitting window based at least partly on the first and second data unit number values of the first layer status report. DESCRIPTION OF DRAWINGS Some example embodiments will now be described, by way of non-limiting and illustrative example only, with reference to the accompanying drawings in which: Fig. 1 shows a representation of an example of a communication system; Fig. 2 shows a representation of an example of apparatus for implementing one or more network functions of the communication system; Fig. 3 shows a representation of an example of user equipment according to some example embodiments; Fig. 4 shows a representation of an example of operations at receiving and transmitting entities according to some example embodiments; Fig. 5 shows a representation of an example of operations at receiving and transmitting entities according to some example embodiments; Fig. 6 shows a representation of an example of operations at receiving and transmitting entities according to some example embodiments; Fig. 7 shows a representation of receiving and transmitting windows according to some example embodiments; and Fig. 8 shows an example of a signaling flow for bearer context set-up at an access node, according to some example embodiments. DETAILED DESCRIPTION In the following, various example embodiments are explained for the example of a user equipment operating according to a 3GPP 5th generation (5G) communication protocol, but the example embodiments may also be applicable to user equipments operating according to other communication protocols. Fig. 1 shows a schematic representation of a 5G communication system (5GS). The 5GS may comprise a user equipment (UE), an access network such as a 5G radio access network (5G-RAN) or next generation radio access network (NG-RAN), a 5G core network (5GC), and one or more application functions. An application function may be deployed in the 5GS as trusted application function or may be deployed or host on one or more application servers of the data network. Such application functions are untrusted application functions. The 5GS connects the UE to a data network the access network and the 5GC (e.g., a UPF of the 5GC). The 5G-RAN may comprise one or more radio access nodes, such as gNodeB (GNB). A gNB may include one or more gNodeB (GNB) distributed units (gNB-DU) connected to gNodeB centralized unit control plane and user plane entities (gNB-CU-CP and gNB-CU-UP). The interface between the gNB-CU-CP entity and the gNB-CU-UP entity is referred to as E1 interface. The interface between the gNB-CU-CP entity and the gNB-DU(s) is referred to as F1-C interface. The interface between the gNB-CU-UP entity and the gNB-DU(s) is referred to as F1-U interface. The 5GC may comprise the following network functions: Network Slice Selection Function (NSSF); Network Exposure Function; Network Repository Function (NRF); Policy Control Function (PCF); Unified Data Management (UDM); Application Function (AF); Authentication Server Function (AUSF); an Access and Mobility Management Function (AMF); and Session Management Function (SMF), and a user plane function (UPF). Fig. 1 also shows the various interfaces (N1, N2 etc.) that may be implemented between the various elements of the system. Fig. 2 illustrates an example of a control apparatus 200 for implementing an instance of a function of the radio access network such as one or more entities of the gNB in Fig. 1. The control apparatus 200 may comprise at least one random access memory (RAM) 211a, at least on read only memory (ROM) 211b, at least one processor 212, 213 and an input / output network interface 214. The at least one processor 212,213 may be coupled to the RAM 211 a and the ROM 211b. The at least one processor 212, 213 may be configured to execute an appropriate software code 215. The execution of the software code 215 may for example allow to perform one or more steps may cause the apparatus to perform one or more of the present aspects operations for implementing an instance function of the access network. The software code 215 may be stored in the ROM 211b. The control apparatus 200 may be interconnected with another control apparatus 200 for implementing one or more instances of other functions of the access network or core network. Fig. 3 illustrates an example of a communication device 300, such as the user equipment (UE) illustrated in Fig. 1 and mentioned in the description of example embodiments below. The communication device 300 may be provided by any device capable of sending and receiving radio signals. Non-limiting examples of a communication device 300 comprise a user equipment, a mobile station (MS) or mobile device such as a mobile phone or what is known as a ’smart phone’, a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), a personal data assistant (PDA) or a tablet provided with wireless communication capabilities, a machine-type communications (MTC) device, an Internet of things (loT) type communication device or any combinations of these or the like. The communication device 300 may comprise a transceiver for transmitting and / or receiving, for example, wireless signals carrying communications, for example radio signals. The communications may be one or more of voice, electronic mail (email), text messages, multimedia data, machine data and so on. The communication device 300 may receive wireless signals (e.g., radio signals) over an air or radio interface 307 via appropriate apparatus for receiving and may transmit wireless signals via appropriate apparatus for transmitting radio signals. In Fig. 3 transceiver is designated schematically by block 306. The transceiver 306 may comprise, for example, a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device and may comprise one or more antenna elements. The antenna arrangement may be a multi-input multi output (MIMO) antenna. The communication device 300 may be provided with at least one processor 301, at least one memory ROM 302a, at least one RAM 302b and other possible components 303 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access networks (e.g., the 5G-RAN or NG-RAN illustrated in Fig. 1) and other communication devices. The at least one processor 301 is coupled to the RAM 302b and the ROM 302a. The at least one processor 301 may be configured to execute an appropriate software code 308. The software code 308 may for example allow to perform one or more operations of the communication device. The software code 308 may be stored in the ROM 302a. The processor, the ROM, and the RAM, the transceiver and other circuitry of the communication device (e.g., a modem) can be provided on a circuit board, in chipsets, or in a system on chip. The circuit board, chipsets or system on chip is denoted by reference 304. The communication device 300 may optionally have a user interface such as key pad 305, touch sensitive screen or pad, combinations thereof or the like. Optionally one or more of a display, a speaker and a microphone may be provided depending on the type of communication device. It is understood that references in the above to various network functions (e.g., to an AMF, an SMF etc.) may comprise apparatus that perform at least some of the functionality associated with those network functions. Further, an apparatus comprising a network function may comprise a virtual network function instance of that network function. It should be understood that the apparatuses may comprise or be coupled to other units or modules etc., such as radio parts or radio heads, used in or for transmission and / or reception. Although the apparatuses have been described as one entity, different modules and memory may be implemented in one or more physical or logical entities. Fig. 4 shows an example of operations at receiving and transmitting entities according to some example embodiments. For the example of uplink transmissions, the receiving (RX) entity may be a gNB; and the transmitting (TX) entity may be a user equipment (UE). As mentioned above, the gNB may comprise a collection of entities e.g. gNB-DU, gNB-CU-CP and gNB-CU-UP. For the example of downlink transmissions, the RX entity may be a UE and the TX entity may be a gNB. As mentioned above, the gNB may comprise a collection of entities e.g. gNB-DU, gNB-CU-CP and gNB-CU-UP. The RX entity receives data units transmitted by the TX entity. The data units have respective data unit number values (hereafter referred to as DU#). For the example of RLC, the data unit values may be referred to as sequence number values by which the RX entity can monitor the reception of data units and provide feedback to the TX entity. Unless specifically specified otherwise, receiving a data unit refers to correctly receiving a data unit (receiving a data unit without error). According to one example, the data units are lower layer data units having respective lower layer DU# carrying higher layer data units having respective higher layer DU#. For the example of PDCP, the higher layer data unit number values may be referred to as Count values. Only the least significant bits of the PDCP Count values, referred to as PDCP sequence number (SN), may be indicated as part of a PDCP data unit. According to one example, the data units are radio link control (RLC) data units having respective RLC sequence number values# and carrying packet data convergence protocol (PDCP) data units having respective PDCP Count values. The TX entity maintains one or more TX windows indicating how high a DU# for which the TX entity can proceed to transmit a data unit. With reference to Fig. 7, the upper edge of a TX window (i.e. the highest DU# for which the TX entity can proceed to transmit a data unit) is defined by the lower edge of the TX window and the window size. The TX entity adjusts the TX window based on feedback from the RX entity. Similarly, the RX entity maintains one or more RX windows indicating the range of DU# for data units whose payload can be delivered to a higher layer. With reference to Fig. 7, the upper edge of the RX window is defined by the lower edge of the RX window and the window size. The RX entity continually adjusts the RX window as it receives data units etc. and sends feedback to the transmitting entity. The feedback provided by the RX entity to the TX entity may take the form of a status report. For the example of RLC data units, the status report may be referred to as a RLC Status protocol data unit (PDU). With reference to Fig. 4, the RX entity makes a determination not to wait to receive one or more unreceived data units having respective one or more DU#, in response to these one or more DU# meeting one or more conditions (OPERATION 400) For example, the one or more conditions for making a “do-not-wait” determination for a DU#n may comprise the expiry of a timer associated with the DU#n. According to one example, the timer may be started in response to receiving a data unit having a DU# higher than DU#n. According to another example, the timer may be started in response to requesting re-transmission of the data unit having DU#n a predetermined number of times. According to another example, the one or more conditions for making a “do-not-wait” determination for a DU#n may comprise receiving a “do-not-wait” indication for DU#n from the transmitting entity. The RX entity sends to the TX entity a status report indicating that the RX entity is no longer waiting to receive the one or more unreceived data units for which a “do-not-wait” determination has been made. (OPERATION 402). Example implementations of this status report are discussed further below. The TX entity adjusts the position of at least one TX window based on the status report received from the RX entity (OPERATION 404). The operations at RX entity may include the RX entity adjusting the position of the RX window based at least partly on the “do-not-wait” determination for one or more DU#. Fig. 5 shows a representation of an example of operations at a transmitting entity transmitting data units, and a receiving entity receiving the data units, according to some example embodiments. Both the RX and TX entities each comprise upper layer and lower entities. The upper layer and lower layer entities may or may not be co-located. For the example of a user equipment, the upper layer and lower layer entities are part of the user equipment. For the example of a gNB: the upper layer entity may be a gNB-CU-UP and the lower layer entity may be a gNB-DU. The gNB-CU-UP and gNB-DU may or may not be colocated. For the example of a UE: the upper and lower layer entities are both part of the UE. The RX entity receives data units transmitted by the TX entity. The data units have respective data unit number values (hereafter referred to as DU#) by which the RX entity can monitor the reception of data units and provide feedback to the TX entity. Unless specifically specified otherwise, receiving a data unit refers to receiving a data unit without error. For the example of RLC, the data unit values may be referred to as sequence number values . According to one example, the data units are lower layer data units having respective lower layer DU# carrying higher layer data units having respective higher layer DU#. For the example of packet data convergence protocol (PDCP), the higher layer data unit number values may be referred to as Count values. According to one example, the data units are radio link control (RLC) data units having respective RLC sequence number values and carrying PDCP units having respective PDCP Count values. According to one example, the lower layer is RLC and the upper layer is PDCP. The RX lower layer entity makes a determination not to wait to receive one or more unreceived lower layer data units having respective one or more DU#, in response to these one or more DU# meeting one or more conditions (OPERATION 500). For example, the one or more conditions for making a “do-not-wait” determination for a DU#n may comprise the expiry of a timer associated with DU#n. According to one example, the timer may be started in response to receiving a data unit having a DU# higher than DU#n. According to another example, the timer may be started in response to sending a request for re-transmission of the data unit having DU#n a predetermined number of times. According to another example, the one or more conditions for making a “do-not-wait” determination for a DU#n may comprise receiving a “do-not-wait” indication for DU#n from the transmitting entity. The RX lower layer entity sends a lower layer status report to the TX peer entity (TX lower layer entity) (OPERATION 502). This lower layer status report distinguishes between (i) one or more first lower layer DU# that are either a DU# of a received lower layer data unit, or a DU# for which a lower layer data unit has not been received and a determination has been made not to wait to receive a lower layer data unit; and (ii) one or more second lower layer DU# for which no lower layer data unit has been received and for which there has been no determination not to wait to receive a lower layer data unit. The lower layer status report does not distinguish between (a) one or more DU# that are a DU# of a received lower layer data unit, and (b) one or more DU# for which a lower layer data unit has not been received and a determination has been made not to wait to receive a lower layer data unit. According to one example, the status report indicates a range of DU# for which the status report provides feedback, and indicates each DU# within the range for which the RX lower layer entity is providing a negative acknowledgement (hereafter referred to as NACK DU#). All other DU# within the range (i.e. all DU# within the range but not indicated to be a NACK DU#) are thus implicitly indicated to be DU# for which the RX lower layer entity is not waiting to receive a data unit (i.e. referred to for this example as ACK DU#). The TX lower layer entity adjusts the position of the lower layer TX window based on the status report (OPERATION 504). The adjustment of the lower layer TX window is based on the implicit ACK DU# (regardless of whether such DU# are DU# of received data units or DU# for which the RX lower layer entity has determined not to wait to receive a data unit; as mentioned above, this distinction is not indicated by the lower layer status report). The RX upper layer entity sends to the TX peer entity (TX upper layer entity) an indication of the position of the upper layer RX window (OPERATION 506). This position indication may be the DU# defining the lower edge of the upper layer RX window. For the example that the upper layer is PDCP, the position indication may comprise the value of a state variable storing the COUNT value of the first PDCP DU not delivered to the upper layers, but still waited for, such as the state variable RXDELIV. The TX upper layer entity adjusts the position of the upper layer TX window based on the indication. According to one example, the indication of the position of the upper layer RX window is sent without any accompanying bitmap field even if upper layer DUs with Count value greater than RX DELIV have been received. According to one example, the indication of the DU# defining the lower edge of the upper layer RX window is included in an upper layer status report that indicates reception at the RX upper layer entity of one or more upper layer DU# received by the RX upper layer entity via the RX lower layer entity. The indication of the DU# defining the lower edge of the upper layer window may be incorporated into the header of an upper layer data unit. According to one example, the sending of this window position indication by the RX upper layer entity is triggered periodically with respect to advancement of the upper layer receiving window. The operations at the RX lower layer entity may include the RX lower layer entity adjusting the position of the lower layer RX window based at least partly on the “do-not-wait” determination for one or more DU#. As discussed further below: according to one example, the TX upper layer entity (e.g. PDCP entity at gNB CU-UP) receives from a TX control plane entity (e.g. gNB CU-CP) a control message indicating that the RX and TX lower layer entities are configured not to distinguish in the lower layer status report between lower layer DU# for which a data unit has been received, and lower layer DU# for which a data unit has not been received but a determination has been made not to wait to receive a data unit. This control message indicates to the TX upper layer user plane entity that the TX upper layer user plane entity is to adjust the upper layer TX window based on the upper layer indications of the position of the upper layer RX window. Fig. 6 shows a representation of another example of operations at a transmitting entity transmitting data units, and a receiving entity receiving the data units, according to some example embodiments. Both the RX and TX entities each comprise upper layer and lower entities. The upper layer and lower layer entities may or may not be co-located. For the example of a user equipment, the upper layer and lower layer entities are part of the user equipment. For the example of a gNB: the upper layer entity may be a gNB CU and the lower layer entity may be a gNB-DU. The gNB-CU and gNB -DU may or may not be colocated. For the example of a UE: the upper and lower layer entities are both part of the UE. According to one example, the lower layer is RLC and the upper layer is PDCP. The RX entity receives data units transmitted by the TX entity. The data units have respective data unit number values (hereafter referred to as DU#) by which the RX entity can monitor the reception of data units and provide feedback to the TX entity. Unless specifically specified otherwise, receiving a data unit refers to receiving a data unit without error. For the example of RLC, the data unit number values may be referred to as sequence number values. According to one example, the data units are lower layer data units having respective lower layer DU# carrying higher layer data units having respective higher layer DU#. For the example of PDCP, the higher layer data unit number values may be referred to as Count values. According to one example, the lower layer data units are radio link control (RLC) data units having respective RLC sequence number values and carrying PDCP data units having respective PDCP Count values. The RX lower layer entity makes a determination not to wait to receive one or more unreceived lower layer data units having respective one or more DU#, in response to these one or more DU# meeting one or more conditions (OPERATION 600). For example, the one or more conditions for making a “do-not-wait” determination for a DU#n may comprise the expiry of a timer associated with the DU#n. According to one example, the timer may be started for DU#n in response to receiving a data unit having a DU# higher than DU#n. According to another example, the timer may be started for DU#n in response to requesting re-transmission of the data unit having DU#n a predetermined number of times. According to another example, the one or more conditions for making a “do-not-wait” determination for a DU#n may comprise receiving a “do-not-wait” indication for DU#n from the transmitting entity. The RX lower layer entity sends a lower layer status report to the TX peer entity (TX lower layer entity) (OPERATION 602). This lower layer status report distinguishes at least between (i) one or more first lower layer DU# that are a DU# of a received lower layer data unit, and (ii) a DU# for which a lower layer data unit has not been received and a determination has been made not to wait to receive a lower layer data unit. According to one example, the status report indicates a range of DU# for which the status report provides feedback, and indicates each DU# within the range for which the RX lower layer entity has not received a data unit and has determined not to wait to receive a data unit (hereafter referred to as Forgotten Dll#). According to this example, the status report may also indicate each DU# within the range for which the RX lower layer entity has not received a data unit and is providing a negative acknowledgement (hereafter referred to as NACK DU#). All other DU# within the range (e.g. all DU# within the range but not indicated to be Forgotten DU# or NACK DU#) are implicitly indicated to be DU# for which the RX lower layer entity has received a data unit (for this example, hereafter referred to as ACK DU#). The TX lower layer entity sends an inter-layer status report to the TX upper layer entity (OPERATION 604). The inter-layer status report indicates (a) one or more upper layer DU# (e.g. Count value for the example of PDCP) carried by the one or more Forgotten DU# indicated by the lower layer status report; and (b) one or more upper layer DU# carried by the one or more lower layer ACK DU#. The TX lower layer entity adjusts the position of the lower layer TX window based on the status report (OPERATION 606). The adjustment of the lower layer TX window is based on the (implicit) lower layer ACK DU# and the lower layer Forgotten DU#. Regarding adjustment of the position of the upper layer TX window: the TX upper layer entity adjusts the position of the upper layer TX window based on the upper layer DU# indicated by the inter-layer status report to have been carried by lower layer ACK DU# (OPERATION 608). For the upper layer DU# corresponding to lower layer Forgotten DU#, the upper layer TX entity makes one or more assumptions about adjustment of the upper layer RX window at the upper layer RX entity. According to one example: for each upper layer data unit submitted by the TX upper layer entity to the TX lower layer entity, the TX upper layer entity starts a timer upon submission of the upper layer data unit to the TX lower layer entity; and the TX upper layer entity progresses the upper layer TX window beyond the upper layer DU# of the data unit upon expiry of the timer associated with that data unit. Regarding a determination about what upper layer data units to re-transmit when a need for re-transmission arises (such as at handover), the TX upper layer entity bases this determination on both (i) the upper layer DU# indicated by the inter-layer status report to correspond to lower layer ACK DUs, and (ii) the upper layer DU# indicated by the inter-layer status report to correspond to lower layer Forgotten DU#. According to some examples, the TX upper layer entity may submit upper layer data units to a plurality of TX lower layer entities for parallel transmission to the RX entity; and the TX upper layer entity may send discard indications to one or more of the plurality of TX lower layer entities based on an inter-layer status report received from another of the plurality of TX lower layer entities. The TX upper layer entity bases this determination on both (i) the upper layer DU# indicated by the inter-layer status report to correspond to lower layer ACK Dus, and (ii) the upper layer DU# indicated by the inter-layer status report to correspond to lower layer Forgotten DU#. The user plane operation of the TX upper layer entity depends on the configuration of the lower layer entities. More particularly, the user plane operation of the TX upper layer entity depends on whether or not the lower layer status report and the inter-layer status report distinguish between (a) DU# for which a data unit has been received and (b) DU# for which a data unit has not been received but a determination has been made not to wait to receive a data unit. According to one example, the TX upper layer entity (e.g. PDCP entity at gNB CU-UP) receives from a TX control plane entity (e.g. gNB CU-CP) an indication of whether or not the lower layer entities are configured to distinguish in the status reports between (a) DU# for which a data unit has been received, and (b) DU# for which a data unit has not been received and a determination has been made not to wait to receive a data unit. For the example of RLC and PDCP as the lower and upper layers, respectively: this indication may be part of step 1 or step 4 of the example shown in Fig. 8 of a signaling flow for bearer-context setup over the E1 and F1 interfaces. In this example, step 3 involves configuration of the one or more RLC entities for the bearer at the gNB-DU (as decided by either the gNB-CU-CP or by the gNB-DU based on e.g. Quality-of-Service (QoS) information from the gNB-CU-CP. Below is described an example embodiment comprising modifications of sections of 3GPP TS 38.323 and 3GPP TS.38.322. The modifications are shown by bold and underlining. 3GPP TS.38.323 4.3.2 Services expected from lower layers A PDCP entity expects the following services from lower layers per RLC entity (for a detailed description see TS 38.322 [5]): acknowledged data transfer service, including indication of successful or discontinued delivery of PDCP PDUs; - unacknowledged data transfer service. A PDCP entity expects the following service from SRAP entity (for a detailed description see TS 38.351 (221), if the PDCP entity is associated with an SRAP entity: data transfer. 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 clause for Uu or PC5 interface. After performing the procedures in this clause, the UE shall follow the procedures in clause 5.2. When upper layers request a PDCP entity re-establishment, the transmitting PDCP entity shall: for AM DRBs for Uu interface whose PDCP entities were suspended, from the first PDCP SDU for which the successful or discontinued delivery of the corresponding PDCP Data PDU has not been confirmed by lower layers, for each PDCP SDU already associated with a PDCP SN: - 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, as specified in clause 5.2.1; for AM DRBs whose PDCP entities were not suspended, from the first PDCP SDU for which the successful or discontinued 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 using ROHC as specified in the clause 5.7.4 and / or using EHC as specified in the clause 5.12.4; If drb-ContinueUDC is configured and if the PDCP SDU has been compressed before: submit the PDCP SDU previously compressed to integrity protection and ciphering function; - else: - perform uplink data compression of the PDCP SDU as specified in clause 5.14.4, and submit the PDCP SDU to integrity protection and ciphering function; perform integrity protection and ciphering of the PDCP SDU using the COUNT value associated with this PDCP SDU as specified in the clause 5.9 and 5.8; submit the resulting PDCP Data PDU to lower layer, as specified in clause 5.2.1. Remainder of section 5.1.2 omitted. 5.2 Data transfer 5.2.1 Transmit operation At reception of a PDCP SDU from upper layers, the transmitting PDCP entity shall: start the discardTimer associated with this PDCP SDU (if configured). For a PDCP SDU received from upper layers, the transmitting PDCP entity shall: - associate the COUNT value corresponding to TXJNEXT to this PDCP SDU; NOTE 1: Associating more than half of the PDCP SN space of contiguous PDCP SDUs with PDCP SNs, when e.g., the PDCP SDUs are discarded or transmitted without acknowledgement confirming successful delivery, may cause HFN desynchronization problem. How to prevent HFN desynchronization problem is left up to UE implementation. - perform header compression of the PDCP SDU using ROHC as specified in the clause 5.7.4 and / or using EHC as specified in the clause 5,12.4; - perform uplink data compression of the PDCP SDU as specified in clause 5.14.4; - perform integrity protection, and ciphering using the TX^NEXT as specified in the clause 5.9 and 5.8, respectively; - set the PDCP SN of the PDCP Data PDU to TX_NEXT modulo increment TX_NEXT by one; submit the resulting PDCP Data PDU to lower layer as specified below. Remainder of section 5.2.1 omitted. 5.2.2 Receive operation 5.2.2.1 Actions when a PDCP Data PDU is received from lower layers If the received PDCP Data PDU with COUNT value = RCVD„COUNT is not discarded above, the receiving PDCP entity shall: - store the resulting PDCP SDU in the reception buffer; - if RCVD„COUNT >= RX_NEXT: - update RX MA I to RCVD_ COUNT + 1. if outOfOrderDelivery is configured: deliver the resulting PDCP SDU to upper layers after performing header decompression using EHC. - if RCVD„COUNT = RXJDELIV: deliver to upper layers in ascending order of the associated COUNT value after performing header decompression, if not decompressed before: all stored PDCP SDU(s) with consecutively associated COUNT value(s) starting from COUNT - RX_DELIV; - update RX^DELIV to the COUNT value of the first PDCP SDU which has not been delivered to upper layers, with COUNT value >RX^ DELIV; - if FMC Report Period is configured and RX DELIV mod FMC Report Period = 0: - compile and transmit the PDCP status report without a Bitmap field, as specified in clause 5.4.1; if t-Reordering is running, and if RX_DELIV >= RX_REORD: stop and reset t-Reordering. - if t-Reordering is not running (includes the case when t-Reordering is stopped due to actions above), and RXJ3EL1V <RXJNEXT: - update RX REORD to RX.NEXT; start t-Reordering. 5.2.2.2 Actions when a t-Reordering expires When t-Reordering expires, the receiving PDCP entity shall: - deliver to upper layers in ascending order of the associated COUNT value after performing header decompression, if not decompressed before: - all stored PDCP SDU(s) with associated COUNT value(s') <RX REORD: all stored PDCP SDU(s) with, consecutively associated COUNT value(s) starting from RX REORD; update RX_DELIV to the COUNT value of the first PDCP SDU which has not been delivered to upper layers, with COUNT value >= RXREORD: - if FMC Report Period is configured and RX DELIV mod EMC Report Period = 0: .:.......................commie.....and......transmit.....the.....PDCP.....status.....report......without.....a......Bitmae......field,.....as.....specified.......in......clause 5.4.1; - if RX„DELIV <RX X EXT: - update RX_REORD to RX XEX f; start t-Reordering. 5.4 Status reporting 5.4.1 Transmit operation For AM DRBs configured by upper layers to send a PDCP status report in the uplink (statusReportRequired in TS 38.331 [3]), the receiving PDCP entity shall trigger a PDCP status report when: - upper layer requests a PDCP entity re-establishment; - upper layer requests a PDCP data recovery': - upper layer requests a uplink data switching; upper layer reconfigures the PDCP entity to release DAPS and daps-SourceRelease is configured in TS 38.331 [3]£ - RX DELIV mod FMC Report Period = 0, if FMC Report Period is configured. Remainder of section 5.4.1 omitted. 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 entities in ascending order of the associated COUNT values for which the successful or discontinued delivery has not been confirmed by lower layers, following the data submission procedure in clause 5.2.1. After performing the above procedures, the transmitting PDCP entity shall follow the procedures in clause 5.2.1. 5.11.2 Duplicate PDU discard For the PDCP entity configured with pdcp-Duplication, the transmitting PDCP entity shall: - if the successful or discontinued delivery of a PDCP Data PDU is confirmed by one of the associated AM RLC entities: indicate to the other AM RLC entities to discard the duplicated PDCP Data PDU; if the deactivation of PDCP duplication is indicated for the DRB: indicate to the RLC entities other than the primary RLC entity to discard all duplicated PDCP Data PDUs; - if the deactivation of PDCP duplication is indicated for at least one associated RLC entities: - indicate to the RLC entities deactivated for PDCP duplication to discard all duplicated PDCP Data PDUs. 5.13 Uplink data switching For DAPS bearers, when upper layers request uplink data switching, the transmitting PDCP entity shall: - for AM DRBs, from the first PDCP SDU for which the successful or discontinued delivery of the corresponding PDCP Data PDU has not been confirmed by the RLC entity associated with the source cell, 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 uplink data switching to the RLC entity associated with the target cell as specified below: - perform header compression of the PDCP SDU using ROHC as specified in the clause 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 clause 5.9 and 5.8, respectively; - submit the resulting PDCP Data PDU to lower layer, as specified in clause 5.2.1. Remainder of section 5.13 omitted. 7.2 Constants a) Window_Size This constant indicates the size of the reordering window. The value equals to ’ for SRB / DRB / MRB and SLRB. b) FMC Report Period This constant indicates the FMC reporting period. The value is configured by upper Savers TS 38.331 [31. TS38.322 5.2.3 AM data transfer 5.2.3.2 Receive operations 5.2.3.2.1 General The receiving side of an AM RLC entity shall maintain a receiving window according to the state variable RX_Next as follows: a SN falls within the receiving window if RX_Next <= SN <RX_Next + AM_Window_Size; - a SN falls outside of die receiving window otherwise. When receiving an AMD PDU from lower layer, the receiving side of an AM RLC entity shall: either discard the received AMD PDU or place it in the reception buffer (see clause 5.2.3.2.2); if the received AMD PDU was placed in the reception buffer: - update state variables, reassemble and deliver RLC SDUs to upper layer and start / stop f-Reassembly and t-Forget as needed (see clause 5.2.3.2.3). When t-Reassembly or t-Forget expires, the receiving side of an AM RLC entity shall: - update state variables and start t-Reassembly or t-Forget, respectively, as needed (see clause 5.2.3.2.4 or 5.2.3.2.5, respectively). 5.2.3.2.3 Actions when an AMD PDU is placed in the reception buffer When an AMD PDU with SN = x is placed in the reception buffer, the receiving side of an AM RLC entity shall: if x >= RX_Next_Highest: - update RX_Next_Highest to x+ 1. if all bytes of the RLC SDU with SN = x are received: reassemble the RLC SDU from AMD PDU(s) with SN = x, remove RLC headers when doing so and deliver the reassembled RLC SDU to upper layer; if x = RX_Highest_Status: - update RX_Highest_Status to the SN of the first RLC SDU with SN >current RX_Highest_Status for which not all bytes have been received. - if x = RX^ Next: update RX_Next to the SN of the first RLC SDU with SN >current RX_Next for which not all bytes have been received. if t-Reassembly is running: - if RX_Next_Status_Trigger = RX. Xext; or - if RX_Next_Status_Trigger = RX_Next + 1 and there is no missing byte segment of the SDU associated with SN = RX_Next before the last byte of all received segments of this SDU; or if RX_Next_Status_Trigger fails outside of the receiving window and RX_Next_Status_Trigger is not equal to RX_Next + AM_Window_Size: stop and reset t-Reassembly. if t-Reassembly is not running (includes the case t-Reassembly is stopped due to actions above): - if RX_NextJdighest> RX JNext +1; or - if RX Next Highew = RX Next + 1 and there is at least one missing byte segment of the SDU associated with SN = RX_Next before the last byte of all received segments of this SDU: start t-Reassembly, set RX_Next_Status_Trigger to RX_Next_Highest. if t-Forset is running: - if RX Forget Trigger = RX Next; or - if RX Forget Trigger = RX Next + 1 and there is no missing byte segment of the SDU associated with SN - RX Next before the last bvte of ah received segments of this SDU: or - ifRX Forget Trigger falls outside of the receiving window and RX Forget Trigger is not equal to RX Next + AM Window Size: - stop and reset t-Forget. if t-Forget is configured and is not running (includes the case t-Forget is stopped due to actions above): - if RX Next Highest> RX Next +1; or - if RX Next Highest = RX Next + 1 and there is at least one missing bvte segment of the SDU associated with SN = RX Next before the last bvte of all received segments of this SDU: start t-Forget-, - set RX Forget Trigger to RX Next Highest. 5.2.3.2.5 Actions when t-Forget expires W hen t-Forget expires, the receiving side of an AM RLC entity shall: - update RX_Next to the SN of the first SN >= RX_Forget_Trigger for which not all bytes have been received; - discard all segments with SN <updated RX_Next; - if RX_Next_Highest >RX_Next + 1: or - if RX_Next_IIighest = RX_Next + 1 and there is at least one missing byte segment of the RLC SDU associated with SN = RX_Next before the last byte of all received segments of this RLC SDU: - start t-Forget; - set RX_Forget_Trigger to RX_Next_Highest. 5.3.4 Status reporting An AM RLC entity sends STATUS PDUs to its peer AM RLC entity in order to provide positive and / or negative acknowledgements of RLC SDUs (or portions of them). Triggers to initiate STATUS reporting include: - Polling from its peer AM RLC entity: - When an AMD PDU with SIN = x and the P field set to "1 ” is received from lower layer, the receiving side of an AM RLC entity shall: - if the AMD PDU is to be discarded as specified in clause 5.2.3.2.2; or - if x <RX_Highest_Status or x >= RX_Next + AM_Window_Size: - trigger a STATUS report. else: - delay triggering the STATUS report until x <RX_Highest_Status or x >= RX^Next + A M_ Windo w^S ize. NOTE 1: This ensures that the RLC Status report is transmitted after HARQ reordering. Detection of reception failure of an AMD PDU The receiving side of an AM RLC entity shall trigger a STATUS report when t-Reassembly expires. NOTE 2: The expiry of t-Reassembly triggers both RX_Highest_Status to be updated and a STATUS report to be triggered, but the STATUS report shall be triggered after RX_Highest_Status is updated. - Forgetting about an unreceived AMD PDU - The receiving side of an AM RLC entity shall trigger a STATUS report when t-Forget expires. NOTE 3: The expiry of t-Forget triggers both RX Next to be updated and a STATUS report to be triggered, but the STATUS report shall be triggered after RX Next is updated. Remainder of section 5.3.4 omitted. 5.4 SDU discard procedures When indicated from upper layer (e.g. PDCP) to discard a particular RLC SDU, the transmitting side of an AM RLC entity configured with t-Forget shall discard the indicated RLC SDU along with anv corresponding RLC Data PDUs. When indicated from upper layer (e.g. PDCP) to discard a particular RLC SDU, the transmitting side of an AM RLC entity not configured with t-Forget or the transmitting UM RLC entity shall discard the indicated RLC SDU, if neither the RLC SDU nor a segment thereof has been submitted to the lower layers. The transmitting side of an AM RLC entity not configured with t-Forget shall not introduce an RLC SN gap when discarding an RLC SDU. 7.1 State variables <...> The receiving side of each AM RLC entity configured with t-Forget shall maintain the following state variables: a)RX Forget Trigger - f-Forgri state variable This state variable holds the value of the SN following the SN of the RLC SDU which triggered t-Forget. 7.3 Timers The following timers are configured by TS 38.331 [5]: a) t-PollRetransmit This timer is used by the transmitting side of an AM RLC entity in order to retransmit a poll (see clause 5.3.3). b) t-Reassembly This timer is used by the receiving side of an AM RLC entity and receiving UM RLC entity in order to detect loss of RLC PDUs at lower layer (see clauses 5.2.2.2 and 5.2.3.2). If t-Reassembly is running, t-Reassembly shall not be started additionally, i.e. only one t-Reassembly per RLC entity is running at a gi ven time. c) t-StatusProhibit This timer is used by the receiving side of an AM RLC entity in order to prohibit transmission of a STATUS PDU (see clause 5.3.4). d) t-Forget When configured, this timer is used by the receiving side of an AM RLC entity in order to forget about unreceived AMD PDUs (see clause 5.2.3.2). If t-Forget is running, t-Forget shall not be started additionally, i.e. only one t-Forget per RLC entity is running at a. given time. In one example configuration, the duration of the t-Forget timer (used to maintain the state variable RX Next, which serves as the lower edge of the reception window) is the same as or similar to the PDCP discard timer, i.e. reflecting the QoS parameter Packet Delay Budget. 5 The above example embodiments provide relatively simple techniques for avoiding retransmitting data that is out-dated from an application layer QoS-requirements point of view. Avoiding the re-transmission of out-dated data can be particularly useful for applications with short packet-delay budgets such as extended Reality (XR) applications. 10 It is noted that whilst some embodiments have been described in relation to 5G networks, similar principles can be applied in relation to other networks and communication systems. Therefore, although certain embodiments were described above by way of example with reference to certain example architectures for wireless networks, technologies and standards, 15 embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein. It is also noted herein that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention. As used herein, “at least one of the following: ” and “at least one of ” and similar wording, where the list of two or more elements are joined by “and” or “or”, mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements. In general, the various embodiments may be implemented in hardware or special purpose circuitry, software, logic or any combination thereof. Some aspects of the disclosure may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the disclosure is not limited thereto. While various aspects of the disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. As used herein, the term “circuitry” may refer to one or more or all of the following: (a) hardware-only circuit implementations (such as implementations in only analog and / or digital circuitry) and (b) combinations of hardware circuits and software, such as (as applicable): (i) a combination of analog and / or digital hardware circuit(s) with software / firmware and (ii) any portions of hardware processor(s) with software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (iii) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.” This definition of circuitry applies to all uses of this term herein, including in any claims. As a further example, as used herein, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device. The embodiments of this disclosure may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware. Computer software or program, also called program product, including software routines, applets and / or macros, may be stored in any apparatus-readable data storage medium and they comprise program instructions to perform particular tasks. A computer program product may comprise one or more computerexecutable components which, when the program is run, are configured to carry out embodiments. The one or more computer-executable components may be at least one software code or portions of it. Further in this regard it should be noted that any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD. The physical media is a non-transitory media. The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM). The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting examples. Various example embodiments of the disclosure may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate. The scope of protection sought for various example embodiments of the disclosure is set out by the independent claims. The example embodiments and features thereof, if any, described in this disclosure that do not fall under the scope of the independent claims are to be 5 interpreted as examples useful for understanding various example embodiments of the disclosure. The foregoing description has provided, byway of non-limiting and illustrative examples, a full and informative description of the various example embodiments of this disclosure. However, 10 various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the claims. However, all such and similar modifications of the teachings will still fall within the various example embodiments of the disclosure as set forth in the claims. By way of non-limiting and illustrative example, there is a further example embodiment comprising 15 a combination of one or more example embodiments with any of the other example embodiments previously discussed.

Claims

1. Apparatus comprising means for:in response to determining that one or more data unit number values meet one or more conditions while yet to receive from a transmitting entity one or more data units having the one or more data unit number values, making a determination not to wait to receive the one or more data units having the one or more data unit number values; andsending a status report to the transmitting entity, wherein the status report indicates that reception of the one or more data units having the one or more data unit number values is no longer waited for.

2. The apparatus according to claim 1, comprising means for progressing a reception window past one or more of the data unit number values for which a determination not to wait to receive a data unit has been made.

3. The apparatus according to claim 1, wherein the one or more conditions for a data unit number value for an unreceived data unit comprise the expiry of a timer associated with the data unit number value for the unreceived data unit.

4. The apparatus according to claim 3, wherein the timer associated with the data unit number value for the unreceived data unit is started in response to receiving a data unit having a data unit number value higher than the data unit number value of the unreceived data unit.

5. The apparatus according to claim 3, wherein the timer is started in response to requesting re-transmission of the data unit a predetermined number of times .

6. The apparatus according to claim 1, wherein the one or more conditions for a data unit number value for an unreceived data unit comprise reception from the transmitting entity of an indication not to wait for the unreceived data unit.7 The apparatus according to any preceding claim, wherein the one or more data units are one or more radio link control layer data units carrying one or more packet data convergence protocol layer data units.

8. The apparatus according to any preceding claim wherein the apparatus is an access node and the transmitting entity is a user equipment.

9. The apparatus according to any of claims 1 to 7, wherein the apparatus is a user equipment and the transmitting entity is an access node.

10. Apparatus comprising means for:receiving a status report from a receiving entity, wherein the status report indicates that the receiving entity is no longer waiting to receive one or more data units having one or more first data unit number values for which the receiving entity has not received one or more data units; andadjusting a position of a transmitting window based on at least the one or more first data unit number values of the status report.

11. The apparatus according to claim 10, wherein the one or more data units are one or more first layer data units carrying one or more second layer data units, and wherein the 5 apparatus comprises means for: delivering from the first layer to the second layer an indication that the receiving entity has not received and is no longer waiting to receive the one or more second layer data units.

12. The apparatus according to claim 10 or claim 11, wherein the one or more data units are one or more radio link control layer data units carrying one or more packet data10 convergence protocol layer data units.

13. The apparatus according to any of claims 10 to 12, wherein the apparatus is an access node and the receiving entity is a user equipment.

14. The apparatus according to any of claims 10 to 12, wherein the apparatus is a user equipment and the receiving entity is an access node.15Application No: GB2404054.5Examiner: Harry DaviesClaims searched: 1-14Date of search: 26 February 2025Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X 1-5, 7, 9-12 US 9473272 B2 (CAVE et al.) - see col. 16 In.53 and col. 18 ln.5-29. X 1-2, 7-14 US 2008 / 0080516 Al (SAMMOUR et al.) - see paras. [0066]-[0067], X 1-5, 7, 9- 12, 14 WO 2008 / 074771 Al (ERICSSON TELEFON AB L M) - see fig.6 and pg.23 In.24 - pg.24 ln.

21. X 1, 3-5, 7-9 WO 2018 / 203794 Al (ERICSSON TELEFON AB L M) - see pg.

27. X 1, 3-5, 7-9 CN 101127587 A (ZTE CORP) - see background section. v A 1, 3-5, 7-9 WO 2022 / 086093 Al (SAMSUNG ELECTRONICS CO LTD) - see fig.2 and para.[43]. X 1, 3-5, 7-9 US 2012 / 0314648 Al (ZHANG et al.) - see fig.2 and paras.[0078]-[0079].Categories:v Au Document indicating lack of novelty or inventive step A Document indicating technological background and or state of the art. Y Document indicating lack of inventive step if combined with one or more other documents of same category. p Document published on or after the declared priority date but before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:The following online and other databases have been used in the preparation of this search reportSEARCH-PATENT, SEARCH-NPLInternational Classification:Subclass Subgroup Valid From H04B 0007 / 26 01 / 01 / 2006 H04L 0001 / 18 01 / 01 / 2023 H04L 0001 / 1829 01 / 01 / 2023

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