Method, apparatus and computer program

Abstract

There is provided a transmitter user equipment comprising means for: determining, based on one or more conditions of a first hop, a preferred packet delay budget for the first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and a relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; sending, to the relay user equipment, a request for a split of an end-to-end packet delay budget associated with the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment, wherein the request comprises the determined preferred packet delay budget for the first hop; receiving, from the relay user equipment, information indicating a packet delay budget for the first hop for the end-to-end radio bearer; and based on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either: accepting the packet delay budget for the first hop and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; or reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment.

Description

A communication network can be seen as a facility that enables communications between two or more communication devices or provides communication devices access to a data network. A mobile or wireless communication network is one example of a communication network. A communication device may be provided with a service by an application server. Such communication networks operate in accordance with standards such as those provided by 3GPP (Third Generation Partnership Project) or ETSI (European Telecommunications Standards Institute). Examples of standards provided by 3GPP are the so-called 3GPP standards for cellular technology generations, such as 3GPP standards for 4G technology and 3GPP standards for 5G technology. 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. According to an aspect, there is provided a transmitter user equipment comprising means for: determining, based on one or more conditions of a first hop, a preferred packet delay budget for the first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and a relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; sending, to the relay user equipment, a request for a split of an end-to-end packet delay budget associated with the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment, wherein the request comprises the determined preferred packet delay budget for the first hop; receiving, from the relay user equipment, information indicating a packet delay budget for the first hop for the end-to-end radio bearer; and based on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either: accepting the packet delay budget for the first hop and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; or reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The request for the split of the end-to-end packet delay budget may further comprise an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the packet delay budget for the first hop may be further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment. Accepting the packet delay budget may comprise: determining, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed; in response to determining that no reconfiguration of the first hop is needed, sending an acceptance message to the relay user equipment accepting the packet delay budget for the first hop; and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. Determining, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed may comprise determining that the packet delay budget for the first hop is greater than or equal to the preferred packet delay budget for the first hop. Reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment may comprise: determining, based on the packet delay budget for the first hop, that a reconfiguration of the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment is needed; in response to determining that a reconfiguration of the first hop is needed, reconfiguring one or more configurations or parameters for packet transmission of the end-to-end radio bearer over the first hop. Determining, based on the packet delay budget for the first hop, that a reconfiguration of the first hop is needed may comprise determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop. Reconfiguring one or more parameters for packet transmission of the end-to-end radio bearer over the first hop may comprise: sending, to the relay user equipment, a sidelink reconfiguration message comprising one or more updated configurations or parameters for packet transmission of the end-to-end radio bearer over the first hop. The means may be further for: determining an updated preferred packet delay budget for the first hop, wherein the sidelink reconfiguration message may further comprise the updated preferred packet delay budget for the first hop. Reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment may comprise releasing the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. According to an aspect there is provided a relay user equipment comprising means for: receiving, from a transmitter user equipment, a request for a split of an end-to-end packet delay budget associated with an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the request comprises a preferred packet delay budget for a first hop, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; determining, based on the request, a packet delay budget for the first hop for the end-to-end radio bearer; and sending, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop for the end-to-end radio bearer. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The request for the split of the end-to-end packet delay budget may further comprise an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein determining the packet delay budget for the first hop may be further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment. The means may be further for: receiving, from the transmitter user equipment, an acceptance message accepting the packet delay budget for the first hop; and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. The means may be further for: receiving, from the transmitter user equipment, a first sidelink reconfiguration message comprising one or more updated configurations or parameters for packet transmission of the end-to-end radio bearer over the first hop; and sending, to the receiver user equipment, a second sidelink reconfiguration message comprising one or more updated configurations or parameters for packet transmissions of the end-to-end radio bearer over a second hop, wherein the second hop is a hop between the relay user equipment and the receiver user equipment in the user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment. The first sidelink reconfiguration message may further comprise an updated preferred packet delay budget for the first hop. The means may be further for: determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop; wherein the sending may comprise sending the information indicating the determined packet delay budget for the first hop when: the determined packet delay budget for the first hop is above the preferred packet delay budget for the first hop minus a configured offset; and / or the determined packet delay budget for the first hop is affordable to the relay user equipment; and / or the preferred packet delay budget for the first hop has been applied for at least a preconfigured time duration. The means may be further for: responsive to sending the information, starting a timer; and if the acceptance message or the first sidelink reconfiguration message is received during the duration of the timer, stopping the timer; or if the acceptance message or the first sidelink reconfiguration message is not received during the duration of the timer, terminating the end-to-end radio bearer upon expiry of the timer. Determining the packet delay budget for the first hop may comprise: determining that the preferred packet delay budget for the first hop is unaffordable; setting the packet delay budget for the first hop to zero; and stopping serving the end-to-end radio bearer between the transmitter user equipment and a receiver user equipment. According to an aspect there is provided a transmitter user equipment comprising means for: receiving, from a relay user equipment, information indicating a packet delay budget for a first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; and based on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either: accepting the packet delay budget for the first hop and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; or reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. The means may be further for: sending, to the relay user equipment, a preferred packet delay budget for the first hop, wherein the packet delay budget for the first hop may be based on the preferred packet delay budget for the first hop. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The means may be further for: sending, to the relay user equipment, an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the packet delay budget for the first hop may be further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment. Accepting the packet delay budget may comprise: determining, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed; in response to determining that no reconfiguration of the first hop is needed, sending an acceptance message to the relay user equipment accepting the packet delay budget for the first hop; and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. Determining, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed may comprise determining that the packet delay budget for the first hop is greater than or equal to a preferred packet delay budget for the first hop for the end-to-end radio bearer. Accepting the packet delay budget may comprise: determining, based on one or more conditions of the first hop, an updated preferred packet delay budget for the first hop for the end-to-end radio bearer; determining, based on the received information indicating the packet delay budget for the first hop and the updated preferred packet delay budget for the first hop, that no reconfiguration of the first hop is needed; in response to determining that no reconfiguration of the first hop is needed, sending an acceptance message to the relay user equipment accepting the packet delay budget for the first hop, wherein the acceptance message further comprises the updated preferred packet delay budget for the first hop; and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. Determining, based on the received information indicating the packet delay budget for the first hop and the updated preferred packet delay budget for the first hop, that no reconfiguration of the first hop is needed may comprise determining that the packet delay budget for the first hop is greater than or equal to the updated preferred packet delay budget for the first hop. Reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment may comprise: determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop; releasing the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment in response to determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop. Reconfiguring the first hop for the end-to-end radio bearer may comprise sending, to the relay user equipment and the receiver user equipment, a sidelink reconfiguration indicating a release of the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. According to an aspect there is provided a relay user equipment comprising means for: determining a change in conditions of a second hop for an end-to-end radio bearer between a transmitter user equipment and a receiver user equipment, wherein the second hop is a hop between the relay user equipment and the receiver user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; determining, based on the determined change in conditions, a packet delay budget for a first hop for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in the user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; and sending, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop. The means may be further for: receiving, from the transmitter user equipment, a preferred packet delay budget for the first hop, wherein determining the packet delay budget for the first hop may be further based on the preferred packet delay budget for the first hop. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The means may be further for: receiving, from the transmitter user equipment, an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein determining the packet delay budget for the first hop may be further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment. The means may be further for: receiving, from the transmitter user equipment, an acceptance message accepting the packet delay budget for the first hop; and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. The determined packet delay budget for the first hop may be greater than or equal to the preferred packet delay budget for the first hop for the end-to-end radio bearer. The determined packet delay budget for the first hop may be less than the preferred packet delay budget for the first hop, and wherein the acceptance message may comprise an updated preferred packet delay budget for the first hop, wherein the determined packet delay budget for the first hop may be greater than or equal to the updated preferred packet delay budget for the first hop. The means may be further for storing the updated preferred packet delay budget for the first hop. The means may be further for: determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop; wherein the sending may comprise sending the information indicating the determined packet delay budget for the first hop when: the determined packet delay budget for the first hop is above the preferred packet delay budget for the first hop minus a configured offset; and / or the determined packet delay budget for the first hop is affordable to the relay user equipment; and / or the preferred packet delay budget for the first hop has been applied for at least a preconfigured time duration. The determined packet delay budget for the first hop may be less than the preferred packet delay budget for the first hop, and wherein the means may be further for: receiving, from the transmitter user equipment, a sidelink reconfiguration message indicating a release of the end-to-end radio bearer between the transmitter user equipment and receiver user equipment; and stopping serving the end-to-end radio bearer between the transmitter user equipment and receiver user equipment in response to receiving the sidelink reconfiguration message. The means may be further for: determining that the preferred packet delay budget for the first hop is unaffordable; setting the packet delay budget for the first hop to zero; and stopping serving the end-to-end radio bearer between the transmitter user equipment and a receiver user equipment. According to an aspect, there is provided a transmitter user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the transmitter user equipment at least to: determine, based on one or more conditions of a first hop, a preferred packet delay budget for the first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and a relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; send, to the relay user equipment, a request for a split of an end-to-end packet delay budget associated with the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment, wherein the request comprises the determined preferred packet delay budget for the first hop; receive, from the relay user equipment, information indicating a packet delay budget for the first hop for the end-to-end radio bearer; and based on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either: accept the packet delay budget for the first hop and maintain the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; or reconfigure the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The request for the split of the end-to-end packet delay budget may further comprise an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the packet delay budget for the first hop may be further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment. The at least one processor may be further configured to cause the transmitter user equipment to: determine, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed; in response to determining that no reconfiguration of the first hop is needed, send an acceptance message to the relay user equipment accepting the packet delay budget for the first hop; and maintain the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. The at least one processor may be further configured to cause the transmitter user equipment to determine that the packet delay budget for the first hop is greater than or equal to the preferred packet delay budget for the first hop. The at least one processor may be further configured to cause the transmitter user equipment to: determine, based on the packet delay budget for the first hop, that a reconfiguration of the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment is needed; in response to determining that a reconfiguration of the first hop is needed, reconfigure one or more configurations or parameters for packet transmission of the end-to-end radio bearer over the first hop. The at least one processor may be further configured to cause the transmitter user equipment to determine that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop. The at least one processor may be further configured to cause the transmitter user equipment to: send, to the relay user equipment, a sidelink reconfiguration message comprising one or more updated configurations or parameters for packet transmission of the end-to-end radio bearer over the first hop. The at least one processor may be further configured to cause the transmitter user equipment to: determine an updated preferred packet delay budget for the first hop, wherein the sidelink reconfiguration message may further comprise the updated preferred packet delay budget for the first hop. The at least one processor may be further configured to cause the transmitter user equipment to release the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. According to an aspect, there is provided a relay user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the relay user equipment at least to: receive, from a transmitter user equipment, a request for a split of an end-to-end packet delay budget associated with an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the request comprises a preferred packet delay budget for a first hop, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; determine, based on the request, a packet delay budget for the first hop for the end-to-end radio bearer; and send, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop for the end-to-end radio bearer. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The request for the split of the end-to-end packet delay budget may further comprise an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the at least one processor may be further configured to cause the relay user equipment to determine the packet delay budget for the first hop based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment. The at least one processor may be further configured to cause the relay user equipment to: receive, from the transmitter user equipment, an acceptance message accepting the packet delay budget for the first hop; and maintain the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. The at least one processor may be further configured to cause the relay user equipment to: receive, from the transmitter user equipment, a first sidelink reconfiguration message comprising one or more updated configurations or parameters for packet transmission of the end-to-end radio bearer over the first hop; and send, to the receiver user equipment, a second sidelink reconfiguration message comprising one or more updated configurations or parameters for packet transmissions of the end-to-end radio bearer over a second hop, wherein the second hop is a hop between the relay user equipment and the receiver user equipment in the user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment. The first sidelink reconfiguration message may further comprise an updated preferred packet delay budget for the first hop. The at least one processor may be further configured to cause the relay user equipment to: determine that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop; wherein the at least one processor may be further configured to cause the relay user equipment to send the information indicating the determined packet delay budget for the first hop when: the determined packet delay budget for the first hop is above the preferred packet delay budget for the first hop minus a configured offset; and / or the determined packet delay budget for the first hop is affordable to the relay user equipment; and / or the preferred packet delay budget for the first hop has been applied for at least a preconfigured time duration. The at least one processor may be further configured to cause the relay user equipment to: responsive to sending the information, start a timer; and if the acceptance message or the first sidelink reconfiguration message is received during the duration of the timer, stop the timer; or if the acceptance message or the first sidelink reconfiguration message is not received during the duration of the timer, terminate the end-to-end radio bearer upon expiry of the timer. The at least one processor may be further configured to cause the relay user equipment to: determine that the preferred packet delay budget for the first hop is unaffordable; set the packet delay budget for the first hop to zero; and stop serving the end-to-end radio bearer between the transmitter user equipment and a receiver user equipment. According to an aspect, there is provided a transmitter user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the transmitter user equipment at least to: receive, from a relay user equipment, information indicating a packet delay budget for a first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; and based on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either: accept the packet delay budget for the first hop and maintain the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; or reconfigure the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. The at least one processor may be further configured to cause the transmitter user equipment to: send, to the relay user equipment, a preferred packet delay budget for the first hop, wherein the packet delay budget for the first hop may be based on the preferred packet delay budget for the first hop. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The at least one processor may be further configured to cause the transmitter user equipment to: send, to the relay user equipment, an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the packet delay budget for the first hop may be further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment. The at least one processor may be further configured to cause the transmitter user equipment to: determine, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed; in response to determining that no reconfiguration of the first hop is needed, send an acceptance message to the relay user equipment accepting the packet delay budget for the first hop; and maintain the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. The at least one processor may be further configured to cause the transmitter user equipment to: determine that the packet delay budget for the first hop is greater than or equal to a preferred packet delay budget for the first hop for the end-to-end radio bearer. The at least one processor may be further configured to cause the transmitter user equipment to: determine, based on one or more conditions of the first hop, an updated preferred packet delay budget for the first hop for the end-to-end radio bearer; determine, based on the received information indicating the packet delay budget for the first hop and the updated preferred packet delay budget for the first hop, that no reconfiguration of the first hop is needed; in response to determining that no reconfiguration of the first hop is needed, send an acceptance message to the relay user equipment accepting the packet delay budget for the first hop, wherein the acceptance message further comprises the updated preferred packet delay budget for the first hop; and maintain the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. The at least one processor may be further configured to cause the transmitter user equipment to determine that the packet delay budget for the first hop is greater than or equal to the updated preferred packet delay budget for the first hop. The at least one processor may be further configured to cause the transmitter user equipment to: determine that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop; release the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment in response to determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop. The at least one processor may be further configured to cause the transmitter user equipment to send, to the relay user equipment and the receiver user equipment, a sidelink reconfiguration indicating a release of the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. According to an aspect, there is provided a relay user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the relay user equipment at least to: determine a change in conditions of a second hop for an end-to-end radio bearer between a transmitter user equipment and a receiver user equipment, wherein the second hop is a hop between the relay user equipment and the receiver user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; determine, based on the determined change in conditions, a packet delay budget for a first hop for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in the user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; and send, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop. The at least one processor may be further configured to cause the relay user equipment to: receive, from the transmitter user equipment, a preferred packet delay budget for the first hop, wherein the packet delay budget for the first hop may be determined further based on the preferred packet delay budget for the first hop. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The at least one processor may be further configured to cause the relay user equipment to: receive, from the transmitter user equipment, an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the packet delay budget for the first hop may be determined further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment. The at least one processor may be further configured to cause the relay user equipment to: receive, from the transmitter user equipment, an acceptance message accepting the packet delay budget for the first hop; and maintain the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. The determined packet delay budget for the first hop may be greater than or equal to the preferred packet delay budget for the first hop for the end-to-end radio bearer. The determined packet delay budget for the first hop may be less than the preferred packet delay budget for the first hop, and wherein the acceptance message may comprise an updated preferred packet delay budget for the first hop, wherein the determined packet delay budget for the first hop may be greater than or equal to the updated preferred packet delay budget for the first hop. The at least one processor may be further configured to cause the relay user equipment to store the updated preferred packet delay budget for the first hop. The at least one processor may be further configured to cause the relay user equipment to: determine that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop; wherein the at least one processor may be further configured to cause the relay user equipment to send the information indicating the determined packet delay budget for the first hop when: the determined packet delay budget for the first hop is above the preferred packet delay budget for the first hop minus a configured offset; and / or the determined packet delay budget for the first hop is affordable to the relay user equipment; and / or the preferred packet delay budget for the first hop has been applied for at least a preconfigured time duration. The determined packet delay budget for the first hop may be less than the preferred packet delay budget for the first hop, and wherein the at least one processor may be further configured to cause the relay user equipment to: receive, from the transmitter user equipment, a sidelink reconfiguration message indicating a release of the end-to-end radio bearer between the transmitter user equipment and receiver user equipment; and stop serving the end-to-end radio bearer between the transmitter user equipment and receiver user equipment in response to receiving the sidelink reconfiguration message. The at least one processor may be further configured to cause the relay user equipment to: determine that the preferred packet delay budget for the first hop is unaffordable; set the packet delay budget for the first hop to zero; and stop serving the end-to-end radio bearer between the transmitter user equipment and a receiver user equipment. According to an aspect, there is provided a method performed by a transmitter user equipment, the method comprising: determining, based on one or more conditions of a first hop, a preferred packet delay budget for the first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and a relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; sending, to the relay user equipment, a request for a split of an end-to-end packet delay budget associated with the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment, wherein the request comprises the determined preferred packet delay budget for the first hop; receiving, from the relay user equipment, information indicating a packet delay budget for the first hop for the end-to-end radio bearer; and based on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either: accepting the packet delay budget for the first hop and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; or reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The request for the split of the end-to-end packet delay budget may further comprise an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the packet delay budget for the first hop may be further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment. Accepting the packet delay budget may comprise: determining, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed; in response to determining that no reconfiguration of the first hop is needed, sending an acceptance message to the relay user equipment accepting the packet delay budget for the first hop; and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. Determining, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed may comprise determining that the packet delay budget for the first hop is greater than or equal to the preferred packet delay budget for the first hop. Reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment may comprise: determining, based on the packet delay budget for the first hop, that a reconfiguration of the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment is needed; in response to determining that a reconfiguration of the first hop is needed, reconfiguring one or more configurations or parameters for packet transmission of the end-to-end radio bearer over the first hop. Determining, based on the packet delay budget for the first hop, that a reconfiguration of the first hop is needed may comprise determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop. Reconfiguring one or more parameters for packet transmission of the end-to-end radio bearer over the first hop may comprise: sending, to the relay user equipment, a sidelink reconfiguration message comprising one or more updated configurations or parameters for packet transmission of the end-to-end radio bearer over the first hop. The method may further comprise: determining an updated preferred packet delay budget for the first hop, wherein the sidelink reconfiguration message may further comprise the updated preferred packet delay budget for the first hop. Reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment may comprise releasing the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. According to an aspect there is provided a method performed by a relay user equipment, the method comprising: receiving, from a transmitter user equipment, a request for a split of an end-to-end packet delay budget associated with an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the request comprises a preferred packet delay budget for a first hop, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; determining, based on the request, a packet delay budget for the first hop for the end-to-end radio bearer; and sending, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop for the end-to-end radio bearer. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The request for the split of the end-to-end packet delay budget may further comprise an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein determining the packet delay budget for the first hop may be further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment. The method may further comprise: receiving, from the transmitter user equipment, an acceptance message accepting the packet delay budget for the first hop; and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. The method may further comprise: receiving, from the transmitter user equipment, a first sidelink reconfiguration message comprising one or more updated configurations or parameters for packet transmission of the end-to-end radio bearer over the first hop; and sending, to the receiver user equipment, a second sidelink reconfiguration message comprising one or more updated configurations or parameters for packet transmissions of the end-to-end radio bearer over a second hop, wherein the second hop is a hop between the relay user equipment and the receiver user equipment in the user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment. The first sidelink reconfiguration message may further comprise an updated preferred packet delay budget for the first hop. The method may further comprise: determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop; wherein the sending may comprise sending the information indicating the determined packet delay budget for the first hop when: the determined packet delay budget for the first hop is above the preferred packet delay budget for the first hop minus a configured offset; and / or the determined packet delay budget for the first hop is affordable to the relay user equipment; and / or the preferred packet delay budget for the first hop has been applied for at least a preconfigured time duration. The method may further comprise: responsive to sending the information, starting a timer; and if the acceptance message or the first sidelink reconfiguration message is received during the duration of the timer, stopping the timer; or if the acceptance message or the first sidelink reconfiguration message is not received during the duration of the timer, terminating the end-to-end radio bearer upon expiry of the timer. Determining the packet delay budget for the first hop may comprise: determining that the preferred packet delay budget for the first hop is unaffordable; setting the packet delay budget for the first hop to zero; and stopping serving the end-to-end radio bearer between the transmitter user equipment and a receiver user equipment. According to an aspect there is provided a method performed by a transmitter user equipment, the method comprising: receiving, from a relay user equipment, information indicating a packet delay budget for a first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; and based on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either: accepting the packet delay budget for the first hop and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; or reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. The method may further comprise: sending, to the relay user equipment, a preferred packet delay budget for the first hop, wherein the packet delay budget for the first hop may be based on the preferred packet delay budget for the first hop. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The method may further comprise: sending, to the relay user equipment, an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the packet delay budget for the first hop may be further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment. Accepting the packet delay budget may comprise: determining, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed; in response to determining that no reconfiguration of the first hop is needed, sending an acceptance message to the relay user equipment accepting the packet delay budget for the first hop; and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. Determining, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed may comprise determining that the packet delay budget for the first hop is greater than or equal to a preferred packet delay budget for the first hop for the end-to-end radio bearer. Accepting the packet delay budget may comprise: determining, based on one or more conditions of the first hop, an updated preferred packet delay budget for the first hop for the end-to-end radio bearer; determining, based on the received information indicating the packet delay budget for the first hop and the updated preferred packet delay budget for the first hop, that no reconfiguration of the first hop is needed; in response to determining that no reconfiguration of the first hop is needed, sending an acceptance message to the relay user equipment accepting the packet delay budget for the first hop, wherein the acceptance message further comprises the updated preferred packet delay budget for the first hop; and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. Determining, based on the received information indicating the packet delay budget for the first hop and the updated preferred packet delay budget for the first hop, that no reconfiguration of the first hop is needed may comprise determining that the packet delay budget for the first hop is greater than or equal to the updated preferred packet delay budget for the first hop. Reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment may comprise: determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop; releasing the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment in response to determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop. Reconfiguring the first hop for the end-to-end radio bearer may comprise sending, to the relay user equipment and the receiver user equipment, a sidelink reconfiguration indicating a release of the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. According to an aspect there is provided a method performed by a relay user equipment, the method comprising: determining a change in conditions of a second hop for an end-to-end radio bearer between a transmitter user equipment and a receiver user equipment, wherein the second hop is a hop between the relay user equipment and the receiver user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; determining, based on the determined change in conditions, a packet delay budget for a first hop for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in the user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; and sending, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop. The method may further comprise: receiving, from the transmitter user equipment, a preferred packet delay budget for the first hop, wherein determining the packet delay budget for the first hop may be further based on the preferred packet delay budget for the first hop. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The method may further comprise: receiving, from the transmitter user equipment, an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein determining the packet delay budget for the first hop may be further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment. The method may further comprise: receiving, from the transmitter user equipment, an acceptance message accepting the packet delay budget for the first hop; and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. The determined packet delay budget for the first hop may be greater than or equal to the preferred packet delay budget for the first hop for the end-to-end radio bearer. The determined packet delay budget for the first hop may be less than the preferred packet delay budget for the first hop, and wherein the acceptance message may comprise an updated preferred packet delay budget for the first hop, wherein the determined packet delay budget for the first hop may be greater than or equal to the updated preferred packet delay budget for the first hop. The method may further comprise storing the updated preferred packet delay budget for the first hop. The method may further comprise: determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop; wherein the sending may comprise sending the information indicating the determined packet delay budget for the first hop when: the determined packet delay budget for the first hop is above the preferred packet delay budget for the first hop minus a configured offset; and / or the determined packet delay budget for the first hop is affordable to the relay user equipment; and / or the preferred packet delay budget for the first hop has been applied for at least a preconfigured time duration. The determined packet delay budget for the first hop may be less than the preferred packet delay budget for the first hop, and wherein the method may further comprise: receiving, from the transmitter user equipment, a sidelink reconfiguration message indicating a release of the end-to-end radio bearer between the transmitter user equipment and receiver user equipment; and stopping serving the end-to-end radio bearer between the transmitter user equipment and receiver user equipment in response to receiving the sidelink reconfiguration message. The method may further comprise: determining that the preferred packet delay budget for the first hop is unaffordable; setting the packet delay budget for the first hop to zero; and stopping serving the end-to-end radio bearer between the transmitter user equipment and a receiver user equipment. According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by a transmitter user equipment, cause the transmitter user equipment to perform at least the following: determining, based on one or more conditions of a first hop, a preferred packet delay budget for the first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and a relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; sending, to the relay user equipment, a request for a split of an end-to-end packet delay budget associated with the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment, wherein the request comprises the determined preferred packet delay budget for the first hop; receiving, from the relay user equipment, information indicating a packet delay budget for the first hop for the end-to-end radio bearer; and based on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either: accepting the packet delay budget for the first hop and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; or reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The request for the split of the end-to-end packet delay budget may further comprise an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the packet delay budget for the first hop may be further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment. Accepting the packet delay budget may comprise: determining, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed; in response to determining that no reconfiguration of the first hop is needed, sending an acceptance message to the relay user equipment accepting the packet delay budget for the first hop; and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. Determining, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed may comprise determining that the packet delay budget for the first hop is greater than or equal to the preferred packet delay budget for the first hop. Reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment may comprise: determining, based on the packet delay budget for the first hop, that a reconfiguration of the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment is needed; in response to determining that a reconfiguration of the first hop is needed, reconfiguring one or more configurations or parameters for packet transmission of the end-to-end radio bearer over the first hop. Determining, based on the packet delay budget for the first hop, that a reconfiguration of the first hop is needed may comprise determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop. Reconfiguring one or more parameters for packet transmission of the end-to-end radio bearer over the first hop may comprise: sending, to the relay user equipment, a sidelink reconfiguration message comprising one or more updated configurations or parameters for packet transmission of the end-to-end radio bearer over the first hop. The instructions, when executed by the transmitter user equipment, may cause the transmitter user equipment to further perform: determining an updated preferred packet delay budget for the first hop, wherein the sidelink reconfiguration message may further comprise the updated preferred packet delay budget for the first hop. Reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment may comprise releasing the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by a relay user equipment, cause the relay user equipment to perform at least the following: receiving, from a transmitter user equipment, a request for a split of an end-to-end packet delay budget associated with an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the request comprises a preferred packet delay budget for a first hop, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; determining, based on the request, a packet delay budget for the first hop for the end-to-end radio bearer; and sending, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop for the end-to-end radio bearer. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The request for the split of the end-to-end packet delay budget may further comprise an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein determining the packet delay budget for the first hop may be further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment. The instructions, when executed by the relay user equipment, may cause the relay user equipment to further perform: receiving, from the transmitter user equipment, an acceptance message accepting the packet delay budget for the first hop; and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. The instructions, when executed by the relay user equipment, may cause the relay user equipment to further perform: receiving, from the transmitter user equipment, a first sidelink reconfiguration message comprising one or more updated configurations or parameters for packet transmission of the end-to-end radio bearer over the first hop; and sending, to the receiver user equipment, a second sidelink reconfiguration message comprising one or more updated configurations or parameters for packet transmissions of the end-to-end radio bearer over a second hop, wherein the second hop is a hop between the relay user equipment and the receiver user equipment in the user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment. The first sidelink reconfiguration message may further comprise an updated preferred packet delay budget for the first hop. The instructions, when executed by the relay user equipment, may cause the relay user equipment to further perform: determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop; wherein the sending may comprise sending the information indicating the determined packet delay budget for the first hop when: the determined packet delay budget for the first hop is above the preferred packet delay budget for the first hop minus a configured offset; and / or the determined packet delay budget for the first hop is affordable to the relay user equipment; and / or the preferred packet delay budget for the first hop has been applied for at least a preconfigured time duration. The instructions, when executed by the relay user equipment, may cause the relay user equipment to further perform: responsive to sending the information, starting a timer; and if the acceptance message or the first sidelink reconfiguration message is received during the duration of the timer, stopping the timer; or if the acceptance message or the first sidelink reconfiguration message is not received during the duration of the timer, terminating the end-to-end radio bearer upon expiry of the timer. Determining the packet delay budget for the first hop may comprise: determining that the preferred packet delay budget for the first hop is unaffordable; setting the packet delay budget for the first hop to zero; and stopping serving the end-to-end radio bearer between the transmitter user equipment and a receiver user equipment. According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by a transmitter user equipment, cause the transmitter user equipment to perform at least the following: receiving, from a relay user equipment, information indicating a packet delay budget for a first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; and based on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either: accepting the packet delay budget for the first hop and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; or reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. The instructions, when executed by the transmitter user equipment, may cause the transmitter user equipment to further perform: sending, to the relay user equipment, a preferred packet delay budget for the first hop, wherein the packet delay budget for the first hop may be based on the preferred packet delay budget for the first hop. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The instructions, when executed by the transmitter user equipment, may cause the transmitter user equipment to further perform: sending, to the relay user equipment, an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the packet delay budget for the first hop may be further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment. Accepting the packet delay budget may comprise: determining, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed; in response to determining that no reconfiguration of the first hop is needed, sending an acceptance message to the relay user equipment accepting the packet delay budget for the first hop; and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. Determining, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed may comprise determining that the packet delay budget for the first hop is greater than or equal to a preferred packet delay budget for the first hop for the end-to-end radio bearer. Accepting the packet delay budget may comprise: determining, based on one or more conditions of the first hop, an updated preferred packet delay budget for the first hop for the end-to-end radio bearer; determining, based on the received information indicating the packet delay budget for the first hop and the updated preferred packet delay budget for the first hop, that no reconfiguration of the first hop is needed; in response to determining that no reconfiguration of the first hop is needed, sending an acceptance message to the relay user equipment accepting the packet delay budget for the first hop, wherein the acceptance message further comprises the updated preferred packet delay budget for the first hop; and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. Determining, based on the received information indicating the packet delay budget for the first hop and the updated preferred packet delay budget for the first hop, that no reconfiguration of the first hop is needed may comprise determining that the packet delay budget for the first hop is greater than or equal to the updated preferred packet delay budget for the first hop. Reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment may comprise: determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop; releasing the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment in response to determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop. Reconfiguring the first hop for the end-to-end radio bearer may comprise sending, to the relay user equipment and the receiver user equipment, a sidelink reconfiguration indicating a release of the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. According to an aspect, there is provided a computer readable medium comprising instructions which, when executed by a relay user equipment, cause the relay user equipment to perform at least the following: determining a change in conditions of a second hop for an end-to-end radio bearer between a transmitter user equipment and a receiver user equipment, wherein the second hop is a hop between the relay user equipment and the receiver user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; determining, based on the determined change in conditions, a packet delay budget for a first hop for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in the user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; and sending, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop. The instructions, when executed by the relay user equipment, may cause the relay user equipment to further perform: receiving, from the transmitter user equipment, a preferred packet delay budget for the first hop, wherein determining the packet delay budget for the first hop may be further based on the preferred packet delay budget for the first hop. The preferred packet delay budget for the first hop may comprise a minimum required packet delay budget for the first hop. The instructions, when executed by the relay user equipment, may cause the relay user equipment to further perform: receiving, from the transmitter user equipment, an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein determining the packet delay budget for the first hop may be further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment. The instructions, when executed by the relay user equipment, may cause the relay user equipment to further perform: receiving, from the transmitter user equipment, an acceptance message accepting the packet delay budget for the first hop; and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment. The determined packet delay budget for the first hop may be greater than or equal to the preferred packet delay budget for the first hop for the end-to-end radio bearer. The determined packet delay budget for the first hop may be less than the preferred packet delay budget for the first hop, and wherein the acceptance message may comprise an updated preferred packet delay budget for the first hop, wherein the determined packet delay budget for the first hop may be greater than or equal to the updated preferred packet delay budget for the first hop. The instructions, when executed by the relay user equipment, may cause the relay user equipment to further perform storing the updated preferred packet delay budget for the first hop. The instructions, when executed by the relay user equipment, may cause the relay user equipment to further perform: determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop; wherein the sending may comprise sending the information indicating the determined packet delay budget for the first hop when: the determined packet delay budget for the first hop is above the preferred packet delay budget for the first hop minus a configured offset; and / or the determined packet delay budget for the first hop is affordable to the relay user equipment; and / or the preferred packet delay budget for the first hop has been applied for at least a preconfigured time duration. The determined packet delay budget for the first hop may be less than the preferred packet delay budget for the first hop, and wherein the instructions, when executed by the relay user equipment, may cause the relay user equipment to further perform: receiving, from the transmitter user equipment, a sidelink reconfiguration message indicating a release of the end-to-end radio bearer between the transmitter user equipment and receiver user equipment; and stopping serving the end-to-end radio bearer between the transmitter user equipment and receiver user equipment in response to receiving the sidelink reconfiguration message. The instructions, when executed by the relay user equipment, may cause the relay user equipment to further perform: determining that the preferred packet delay budget for the first hop is unaffordable; setting the packet delay budget for the first hop to zero; and stopping serving the end-to-end radio bearer between the transmitter user equipment and a receiver user equipment. According to an aspect, there is provided a non-transitory computer readable medium comprising program instructions that, when executed by an apparatus, cause the apparatus to perform at least the method according to any of the preceding aspects. In the above, many different embodiments have been described. It should be appreciated that further embodiments may be provided by the combination of any two or more of the embodiments described above. DESCRIPTION OF FIGURES Some example embodiments will now be described, by way of non-limiting and illustrative example only, with reference to the accompanying Figures in which: FIG. 1 shows a representation of a 5th generation communication system; FIG. 2 shows a representation of an apparatus for the communication system of FIG. 1 according to some example embodiments; FIG. 3 shows a representation of an apparatus according to some example embodiments; FIG. 4 shows methods according to some examples; FIG. 5 shows an example procedure for establishing end-to-end SL-SRB / DRBs with a Remote UE; FIG. 6 shows an example procedure for exchanging UE information in a SL connection; FIG. 7 shows methods according to some examples; FIGs. 8 to 12 show examples of successful and unsuccessful QoS split operations; and FIG. 13 shows a schematic representation of an apparatus according to some examples. DETAILED DESCRIPTION In the following various example embodiments are explained with reference to communication devices capable of communication with a communication system. Before explaining in detail the embodiments of the methods and apparatuses of the present disclosure, a 5th generation communication system (5GS), an access network and a core network (5GC) thereof, and communication devices are briefly explained with reference to FIGs. 1, 2 and 3. FIG. 1 shows a schematic representation of a 5G communication system (5GS). The 5GS may comprise a user equipment (UE) or Terminal 100, an access network such as a 5G radio access network (5G-RAN) 101 or next generation radio access network (NG-RAN), a 5G core network 102, and one or more application functions 103. An application function 103 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 (DN) 104. Such application functions are untrusted application functions. The 5GS connects the UE to a data network the access network and the 5GC 102 (e.g., a UPF of the 5GC). The 5G-RAN 101 may comprise one or more radio access nodes, such as gNodeB (gNB). A gNB may include one or more gNodeB (GNB) distributed units (DU) connected to one or more gNodeB (GNB) centralized units (CU). The 5GC 102 may comprise the following network functions: Network Slice Selection Function (NSSF); Network Exposure Function (NEF) 105; Network Repository Function (NRF); Policy Control Function (PCF); Unified Data Management (UDM) 106; Authentication Server Function (AUSF) 107; an Access and Mobility Management Function (AMF) 108; Session Management Function (SMF) 109; and a user plane function (UPF) 110. 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 controlling a function of the access network (e.g., a5G-RAN or the NG-RAN illustrated in FIG. 1) illustrated on 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 a network interface 214. The at least one processor 212, 213 may be coupled to the RAM 211a and the ROM 211b. The at least one processor 212, 213 may be configured to execute an appropriate software code 215. Execution of the software code 215 may for example may cause the apparatus to perform operations for controlling a 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 controlling another function of the 5G-RAN or the NG-RAN. In some embodiments, each function of the 5G-RAN or the NG-RAN is deployed or hosted on a control apparatus 200. In alternative embodiments, two or more functions of the 5G-RAN or the NG-RAN may share a control apparatus. FIG. 3 illustrates an example of a communication device 300, such as the UE or Terminal illustrated on FIG. 1. 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 keypad 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. In some examples, a remote UE may establish a sidelink (SL) connection with another remote UE via a UE-to-UE relay UE. The UE-to-UE relay UE may be referred to herein as a relay UE. The SL connection may enable the two remote UEs to communicate with each other (directly or indirectly via the relay UE) without the need to send and receive messages from an access node (e.g., gNB). For example, a message may be sent from a first remote UE, via a first hop, to the relay UE. The relay UE may then send (forward) the message, via a second hop, to the second remote UE. FIG. 4a and 4b illustrate example protocol stacks for the user plane (FIG. 4a) and control plane (FIG. 4b) for a SL connection between two remote UEs via a relay UE. As is shown in FIG. 4a and 4b, a Sidelink Relay Adaptation Protocol (SRAP) sublayer may be placed above a Radio Link Control (RLC) sublayer for both control plane (CP) and user plane (UP) at the PC5 interfaces. The sidelink Service Data Adaptation Protocol (SDAP), Packet Data Convergence Protocol (PDCP) and Radio Resource Control (RRC) layers may be terminated between two Remote UEs, while SRAP, RLC, Medium Access Control (MAC) and Physical (PHY) layers may be terminated in each hop of PC5 link. At the relay UE, the SRAP sublayer may perform bearer mapping between end-to-end PC5 Radio Bearers (e.g., SL Signalling Radio Bearers (SRBs) or SL Data Radio Bearers (DRBs)) of the Remote UE and at each hop of the PC5 Relay RLC Channel between the Remote UE and the Relay UE. For the traffic transmitted from a Remote UE to a Relay UE, the different end-to-end PC5 Radio Bearers (e.g., SL-SRBs or SL-DRBs) towards the same Remote UE and / or different Remote UEs can be multiplexed by the SRAP sublayer at the Relay UE to the same PC5 Relay RLC channel between the Remote UE(s) and the Relay UE. For the traffic received at the Remote UE, the same PC5 Relay RLC channel from one Relay UE can be de-multiplexed to the different end-to-end PC5 Radio Bearers (e.g., SL-SRBs or SL-DRBs) of the same peer Remote UE and / or different Remote UEs. The SRAP sublayer at the Remote UE may support identification of the Remote UE and another Remote UE, also referred to as peer Remote UEs, for example based on local IDs. The local IDs may be assigned by the Relay UE to both Remote UEs for identification. The local IDs of the Remote UEs may be delivered by the Relay UE to the Remote UEs. The identity information of the end-to-end PC5 Radio Bearer and two local IDs of the Remote UEs (peer Remote UEs) may be included in the SRAP header in order for the Remote UE to correlate the received packets for the specific PDCP entity associated with the right end-to-end PC5 Radio Bearer of the Remote UEs. The SRAP sublayer at Relay UE may determine an egress PC5 Relay RLC Channel based on the mapping of the end-to-end PC5 Radio Bearer and egress PC5 Relay RLC Channel for a particular pair between the Remote UEs. For ingress traffic received from an / multiple Remote UE(s) at the Relay UE, the different end-to-end PC5 Radio Bearers (e.g., SL-SRBs or SL-DRBs) of the same Remote UE and / or the same / different end-to-end PC5 Radio Bearers (e.g., SL-SRBs or SL-DRBs) of Remote UEs can be multiplexed to the same egress PC5 Relay RLC channel between the Relay UE and a Remote UE. FIG. 5 illustrates an example procedure for establishing end-to-end SL-SRB / DRBs with a Remote UE. The procedure of FIG. 5 may have to be performed before user plane data transmission between the remote UEs can occur. As used herein, the Remote UE refers to the transmitting UE in the SL-based U2U relay connection and the peer Remote UE refers to the receiving UE in the SL-based U2U relay connection. At 500, the Remote UE, Relay UE, and peer Remote UE perform discovery procedure or integrated discovery procedure to discover each other. The integrated discovery procedure is referred to a SL connection establishment integrated with U2U relay discovery for the SL-based U2U relay connection between the Remote UE and peer Remote UE via the Relay UE. At 502a the Remote UE establishes or modifies a PC5-RRC connection with the Relay UE (e.g., as specified in 3GPP TS 23.304). At 502b the Relay UE establishes or modifies a PC5-RRC connection with the peer Remote UE (e.g., as specified in 3GPP TS 23.304). At 504, the Relay UE allocates two local IDs which are delivered via a message (e.g., a RRCReconfigurationSidelink message) to each of the Remote UEs. One local ID identifies the Remote UE, the other local ID identifies the peer Remote UE. When the local ID is delivered, an L2 ID of the peer Remote UE is also delivered to the Remote UE for making the association between the local ID and the L2 ID of the peer Remote UE. At 506 the Remote UE establishes end-to-end PC5-RRC connection with the peer Remote UE via the Relay UE. For the end-to-end connection establishment, fixed indexes (e.g., 0 / 1 / 2 / 3) may be defined for end-to-end SL-SRB respectively. A specified PC5 Relay RLC Channel configuration may be used on each hop. The sidelink UE capability may be exchanged between Remote UEs via PC5-RRC (e.g., SL-SRB3) message. At 508 the Remote UE sends to the Relay UE the QoS profile(s) for the end-to-end QoS flow(s) via PC5-RRC. The QoS flow(s) may be associated with the end-to-end SL-DRB between the Remote UE and peer Remote UE. At 510 the Relay UE determines a QoS split for the packet delay budget (PDB). For example, the Relay UE may split the end-to-end PDB for the end-to-end QoS flow(s) or the associated end-to-end SL-DRB between the first hop (between Remote UE and Relay UE) and the second hop (between the Relay UE and the peer Remote UE). How the Relay UE determines the split of the PDB may be implementation specific. At 512 the Relay UE sends a message comprising the split QoS value for the first hop (e.g., as the end-to-end PDB is split between the first hop and second hop) to the Remote UE. At 514 the Remote UE or the serving gNB of the Remote UE derives PDCP and SDAP reconfiguration for end-to-end SL-DRB and provides the portion of the configuration related to reception to the peer Remote UE using end-to-end RRCReconfigurationSidelink messages. The end-to-end bearer IDs for SL-SRB and SL-DRB are used as input for Relay ciphering and deciphering at PDCP. At 516, based on the split QoS value for the first hop (as received from the Relay UE at 512), the Remote UE or the serving gNB of the Remote UE derives the first hop configuration (e.g. PC5 Relay RLC Channel configuration) for SL-DRB and provides to the Relay UE the configuration related to receiving on the first hop (i.e., Rx by the relay UE), using per-hop RRCReconfigurationSidelink message. At 518, based on the QoS split between the first hop and the second hop (as determined by the Relay UE at 510), the Relay UE or the serving gNB of the Relay UE derives the second hop configuration (e.g. PC5 Relay RLC Channel configuration) for each SL-DRB and provides to the peer Remote UE the configuration related to receiving data packets on the second hop (i.e., RX by the peer remote UE), using per-hop RRCReconfigurationSidelink message. At 520 the Remote UE and the peer Remote UE transmit or receive data via Relay UE for the end-to-end SL-DRB. FIG. 6 shows an example procedure for exchanging UE information in a SL connection. The procedure shown in FIG. 6 may be used for performing QoS split negotiation. For example, the Remote UE may send its end-to-end QoS information (which may correspond to step 508 above) to the Relay UE in a UElnformationRequestSidelink message at 600, and the Relay UE may send the split QoS information of the first-hop (which may correspond to step 512 above) to the Remote UE in a UElnformationResponseSidelink message at 602. An example UElnformationRequestSidelink message is shown below: - ASN1 START - TAG-UEINFORMATIONREQUESTSIDELINK-START UEInformationRequestSidelink-r18 ::= SEQUENCE { rrc-Transactionldentifier-r16 RRC-Transactionidentifier, criticalExtensions CHOICE { uelnformationRequestSidelink-r18 UEInformationRequestSidelink-r18-IEs, criticalExtensionsFuture SEQUENCE {} } UEInformationRequestSidelink-r18-IEs ::= SEQUENCE { sl-E2E-QoS-ConnectionListPC5-r18 SEQUENCE (SIZE (1.. maxNrofSL-Dest-r16)) OF SL-E2E-QoS-ConnectionPC5-r18 OPTIONAL, - Need N lateNonCriticalExtension OCTET STRING OPTIONAL, nonCriticalExtension SEQUENCE {} OPTIONAL } SL-E2E-QoS-ConnectionPC5-r18 ::= SEQUENCE { sl-DestinationldentityRemoteUE-r18 SL-Destinationldentity-r16, sl-QoS-lnfoList-r18 SEQUENCE (SIZE (1..maxNrofSL-QFIsPerDest-r16)) OF SL- QoS-lnfo-r16 } - TAG-UEINFORMATIONREQUESTSIDELINK-STOP - ASN1STOP The SL-E2E-QoS-ConnectionListPC5 may indicate the QoS info for a list of end-to-end PC5 connections with each connection indicated by the destination L2 ID of the peer L2 U2U Remote UE. An example UElnformationResponseSidelink message is shown below. -ASN1START - TAG-UEINFORMATIONRESPONSESIDELINK-START UEInformationResponseSidelink-r18 ::= SEQUENCE { rrc-Transactionldentifier-r16 RRC-Transactionldentifier, critica / Extensions CHOICE { uelnformationResponseSidelink-r18 UEInformationResponseSidelink-r18-1 Es, critical ExtensionsFuture SEQUENCE {} ::= SEQUENCE / SEQUENCE (SIZE (1.. maxNrofSL-Dest-r16)) OF SL- OPTIONAL, - Need N OCTET STRING UEInformationResponseSidelink-r18-IEs sl-SplitQoS-ConnectionListPC5-r18 SplitQoS-ConnectionPC5-r18 late Non CriticalExtension OPTIONAL, non CriticalExtension OPTIONAL SEQUENCE {} SL-SplitQoS-ConnectionPC5-r18 ::= sl-DestinationldentityRemote UE-r18 sl-SplitQoS-lnfoList-r18 r16)) OF SL-SplitQoS-lnfo-r18 SEQUENCE{ SL-Destinationldentity-r16, SEQUENCE (SIZE (1.. maxNrofSL-QFIsPerDest- SL-SplitQoS-lnfo-r18 ::= sl-QoS-Flowldentity-r18 sl-SplitPacketDelayBudget-r18 OPTIONAL - Need M SEQUENCE{ SL-QoS-Flowldentity-r16, INTEGER (0.. 1023) - TAG-UEINFORMATIONRESPONSESIDELINK-STOP - ASN1STOP The sl-SplitQoS-ConnectionListPC5 may indicate the split PDB on the first PC5 hop between Relay UE and the Remote UE for a list of end-to-end connection. Radio conditions including at least SL resource and channel conditions on the first hop and second hop described above are dynamically varying. It could therefore be the case that a QoS split for PDB of the first hop and second hop for an E2E RB (SL-DRB) becomes sub-optimal after it has been assigned by the Relay UE due to the change in radio conditions. Furthermore, the relay UE (which may determine the PDB split) may not have knowledge of the conditions on the first hop, meaning that the PDB split may be sub-optimal. It may be beneficial for the QoS split of PDB for the first hop and second hop for the E2E RB to be dynamically configurable to be able to adapt to such conditions in order to meet E2E PDB effectively and efficiently. It is noted that end-to-end QoS flows associated with the E2E RB may also dynamically change over time, e.g., due to possible addition, removal or modification of an E2E QoS flow associated with the E2E RB during the E2E communication. Therefore, the QoS split may need to be renegotiated or adapted for the E2E RB due to change of E2E QoS flow mapped on the E2E RB as well. Some examples of the present disclosure address these problems. Some examples may provide mechanisms to enable and facilitate QoS split and L2 reconfiguration adapted to conditions of the first hop and second hop. Reference is made to FIG. 7, which shows methods according to some examples. At 700, a method comprises determining, based on one or more conditions of a first hop, a preferred packet delay budget for the first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and a relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment. At 702, the method comprises sending, to the relay user equipment, a request for a split of an end-to-end packet delay budget associated with the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment, wherein the request comprises the determined preferred packet delay budget for the first hop. At 704, the method comprises receiving, from the relay user equipment, information indicating a packet delay budget for the first hop for the end-to-end radio bearer. At 706, the method comprises based on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either: accepting the packet delay budget for the first hop and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; or reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment In some examples the method of steps 700-706 may be performed by a transmitter user equipment. At 708, a method comprises receiving, from a transmitter user equipment, a request for a split of an end-to-end packet delay budget associated with an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the request comprises a preferred packet delay budget for a first hop, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment. At 710 the method comprises determining, based on the request, a packet delay budget for the first hop for the end-to-end radio bearer. At 712 the method comprises sending, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop for the end-to-end radio bearer. In some examples the method of steps 708-712 may be performed by a relay user equipment. At 714, a method comprises receiving, from a relay user equipment, information indicating a packet delay budget for a first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment. At 716, the method comprises, based on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either: accepting the packet delay budget for the first hop and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; or reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. In some examples the method of steps 714-716 may be performed by a transmitter user equipment. At 718, a method comprises determining a change in conditions of a second hop for an end-to-end radio bearer between a transmitter user equipment and a receiver user equipment, wherein the second hop is a hop between the relay user equipment and the receiver user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment. At 720 the method comprises determining, based on the determined change in conditions, a packet delay budget for a first hop for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in the user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment. At 722 the method comprises sending, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop. In some examples the method of steps 718-722 may be performed by a relay user equipment. In some examples a remote UE, acting as transmitter of the first hop, may send a request to a relay UE for a new QoS split of an end-to-end (E2E) PDB for an existing E2E RB between the remote UE and a peer remote UE based on one or more conditions of the first hop. The request may for example comprise the QoS profile(s) for the end-to-end QoS flow(s) associated with the E2E RB sent at 508 or the UElnformatioRequestSidelink message sent at 600. The request for the split of the E2E PDB comprises a preferred PDB for the first hop for the E2E RB. The preferred PDB for the first hop for the may for example comprise a minimum required PDB for the first hop, which may be denoted as MinRequiredlstHopPDB herein. The request for the split of the E2E PDB may further comprise information indicating the ID of the associated E2E RB and the E2E PDB. The preferred PDB for the first hop may be determined by the remote UE based on one or more conditions of the first hop. For example, the remote UE may determine one or more conditions, such as the channel busy rate (CBR) associated with the first hop, and determine the preferred PDB for the first hop based on the determined one or more conditions. In some examples the remote UE may initiate a new QoS split request for a new E2E RB, or for an existing E2E RB that has been provided with a current first hop PDB by the relay UE. For example, the remote UE may send the QoS split request in response to determining that the one or more conditions on the first hop have changed (e.g., the one or more conditions are such that a current first hop PDB allocated by the relay UE cannot be satisfied). In some examples when the one or more conditions on the first hop have changed such that the current first hop PDB cannot be satisfied, the preferred PDB for the first hop in the new QoS split request may be set larger than the current first hop PDB. In some examples, a relay UE, acting as transmitter UE of the second hop, may determine one or more conditions on the second hop. The relay UE may determine a need of updating a second hop PDB for an existing E2E RB based on the one or more conditions on the second hop. For example, the relay UE may determine that the one or more conditions on the second hop have changed (e.g., the one or more conditions are such that a current second hop PDB cannot be satisfied). In some examples, the relay UE, either in response to receiving the QoS split request from the remote UE on the first hop or determining a need of updating a second hop PDB for an existing E2E RB based on the one or more conditions of the second hop, may determine a new first-hop PDB for the corresponding E2E RB of the remote UE. The new first hop PDB may be determined based on the preferred PDB for the first hop and / or the one or more conditions on the second hop. For example, the relay UE may determine a first hop PDB based on the overall PDB or, that is, the E2E PDB for the E2E RB and the one or more conditions of the second hop, while trying to satisfy the preferred PDB for the first hop of the first hop for the E2E RB. The relay UE may then send information indicating the PDB for the first hop to the remote UE. The information indicating the PDB for the first hop may comprise a QoS split indication. The information indicating the PDB for the first hop may correspond to the QoS Split Information sent at 512 or UElnformationResponseSidelink sent at 602. In some examples, the first hop PDB indicated by the relay UE may be between the preferred PDB for the first hop and E2E PDB (i.e., the preferred PDB for the first hop is satisfied). Such cases may be considered successful cases. In some examples, the relay UE cannot afford to provide the first hop PDB equal to or above the preferred PDB for the first hop. Such cases may be considered unsuccessful or failure cases. In some examples for an unsuccessful or failure case, as a first option, the first hop PDB indicated by the relay UE to the remote UE may be set to an affordable value (that is, affordable to the relay UE) below the indicated preferred PDB for the first hop. The remote UE may then determine whether to accept the indicated first hop PDB or to initiate a release of the corresponding E2E RB. The first hop PDB may be set to the affordable value when at least one of the following conditions is met: • The affordable value is above preferred PDB for the first hop minus a configured offset; • The affordable value can be met over SL, as determined by the relay UE; or • The preferred PDB for the first hop has been applied for at least a preconfigured time duration, Tmin. Tmin may be an implementation specific parameter and is understood as being a period of time long enough such that the preferred PDB for the first hop may no longer reflect current conditions on the first-hop. In some examples for an unsuccessful or failure case, as a second option, the first-hop PDB may be set to zero (a specified constraint in general) to indicate that the relay UE stops serving the corresponding E2E RB. The remote UE may then release the corresponding E2E RB with its peer remote UE and indicate the release to the upper layer. The second option may be used either instead of the first option or when at least one of the conditions associated with the first option is not met. In some examples the remote UE, upon receiving the information indicating the PDB for the first hop from the relay UE, may either accept the indicated PDB for the first hop and maintain the E2E RB, or may reconfigure the first hop for the E2E RB. In some examples, when the remote UE accepts the indicated PDB, the remote UE may send an acceptance message to the relay UE accepting the indicated PDB. The remote UE may accept the indicated PDB for the first hop in response to determining that the indicated PDB does not require the remote UE to initiate a SL RRC Reconfiguration to modify or release the existing E2E RB and / or other related configuration on the first hop. That is to say, the current SL configuration can be used to meet the first hop PDB indicated by the relay UE. In some examples, when the remote UE reconfigures the first hop for the E2E RB, the remote UE may initiate a SL RRC Reconfiguration to the relay UE. For example, the remote UE may send a SL RRC Reconfiguration message to the relay UE (e.g., as per step 516). The SL RRC Reconfiguration, or more generally reconfiguring the first hop, may refer to a reconfiguration of one or more lower protocol layer(s) (e.g., PC5-RLC, PC5-MAC, PC5-PHY shown in FIG. 4) configurations or one or more parameters thereof for carrying the E2E RB or, that is, for transmitting packets of the E2E RB. For example, the reconfiguring may be to change one or more parameters associated with the E2E RB. For example, as PDB has direct impact on maximum allowed number of retransmissions for a packet or resource selection in time for a (re)transmission of a packet, a hierarchy of transmissions scheduled on the E2E RB may be changed based on the SL RRC Reconfiguration. In some examples, when the remote UE reconfigures the first hop for the E2E RB, the remote UE may send, to the relay UE, a first SL RRC Reconfiguration message comprising one or more updated configurations or parameters for packet transmission of the E2E RB over the first hop. The relay UE may then send, to the peer remote UE, a second SL RRC Reconfiguration message comprising one or more updated configurations or parameters for packet transmission of the E2E RB over the second hop. The one or more updated configurations or parameters for packet transmission of the E2E RB over the second hop may be based at least in part on the one or more updated configurations or parameters for packet transmission of the E2E RB over the first hop. In some examples the relay UE may utilise a timer T for operations related to the transmitting of the QoS split indication. In some examples the relay UE may start timer T upon transmitting the QoS split indication to the remote UE. Timer T may be stopped at the relay UE upon receiving either an acceptance message or a SL RRC Reconfiguration message from the remote UE before Timer T expires. Upon expiry of timer T without receiving an acceptance message or a SL RRC Reconfiguration message from the remote UE, the relay UE may stop serving the corresponding E2E RB. In some examples the relay UE may send an indication that the relay UE is stopping serving the corresponding E2E RB to the remote UE and / or peer remote UE. In some examples the remote UE may update the relay UE with a new value of the preferred PDB for the first hop (e.g., a new MinRequiredlstHopPDB) for an existing E2E RB. The remote UE may determine the new value of the preferred PDB for the first hop based on one or more conditions of the first hop and update the relay UE with the new value when the new value of the preferred PDB for the first hop is under a current first-hop PDB of the existing E2E RB. In some examples the update may be performed when the new value of the preferred PDB for the first hop is larger than the current value of the preferred PDB for the first hop and under the current first-hop PDB for the E2E RB. The update of the preferred PDB for the first hop may therefore not be sent for requesting a new QoS split, but to keep the preferred PDB for the first hop up to date in the relay UE for the E2E RB. This may be advantageous considering that the relay UE may initiate a new QoS split for the existing E2E RB at any time due to possible changes of the second hop radio conditions and thus having an updated preferred PDB for the first hop is beneficial for the U2U relay UE to determine the new QoS split effectively. The update may be performed using different SL messages, such as but not limited to QoS split request, acceptance message, or UE assistance information. Upon receiving the update, the relay UE may store the updated preferred PDB for the first hop and may not send a response to the update. In some examples, the remote UE may indicate to the relay UE (e.g., in SL RRC Reconfiguration message, UE assistance information or the QoS split request) one or more PDB threshold(s) (or PDB range(s)) for the first hop corresponding to an existing E2E RB. The PDB threshold(s) or ranges may be denoted as an update PDB for the first hop (which may in some examples be referred to as UpdateThreslstHopPDB). The update PDB for the first hop may indicate one or more first hop PDB value(s) or range(s) that will trigger a SL RRC Reconfiguration from the remote UE to the relay UE for the existing E2E RB. The value(s) of the update PDB for the first hop may be larger than the value of the preferred PDB for the first hop. The remote UE may determine the value(s) of the update PDB for the first hop based on, for example, the PDB value ranges that may lead to different configurations for SL relay RLC channel and / or lower layer protocol configuration on the 1st-hop for the E2E RB. In some examples the relay UE may take the update PDB for the first hop into account when determining to perform a new QoS split for the existing E2E RB such that SL RRC Reconfiguration from the remote UE for the first hop for the E2E RB can be avoided as much as possible. In some examples the relay UE may adapt QoS split for the existing E2E RB when the conditions of the second hop change. In such examples the relay UE may initiate a new QoS split indication for the existing E2E RB to update the first hop PDB to the remote UE only if the updated first hop PDB is crossing the value of the update PDB for the first hop. For example, if the previously indicated first-hop PDB is lower than UpdateThreslstHopPDB, the QoS split indication may be triggered if the first hop PDB needs to change higher than UpdateThreslstHopPDB, or vice versa. In other words, if the split first hop PDB does not exceed the update PDB for the first hop for the existing E2E RB then no update via a new QoS split indication from the relay UE to the remote UE is sent. Furthermore, an acceptance message may not be sent from the remote UE in response, as SL RRC Reconfiguration from the remote UE for the first hop is expected in response to a QoS split indication received from U2U relay UE. Reference is made to FIG. 8, which illustrates an example of successful QoS split operation in which a remote UE initiates a new QoS split for an existing E2E RB based on one or more conditions on the first hop. At 800 the remote UE, relay UE, and peer remote UE establish a SL relay connection for E2E communication between the remote UE and peer remote UE via the relay UE, including an E2E RB mapped on a first hop RLC channel and a second hop RLC channel, for example as described in relation to FIG. 5. Thus, all the relevant current configurations of the E2E connection, first hop and second hop and parameters (such as the preferred PDB for the first hop (e.g., MinReqlstHopPDB) or the update PDB for the first hop (e.g., UpdateThreslstHopPDB)) for the existing E2E RB are in place. At 802 the remote UE determines to initiate a new QoS split for the E2E RB. This may for example be due to determining a change in one or more conditions associated with the first hop as described previously. At 804 the remote UE sends, to the relay UE, a request for a split of an E2E PDB associated with the E2E RB. The request may be as described previously - for example the request may comprise the preferred PDB for the first hop or the update PDB for the first hop, and optionally an identifier of the E2E RB and / or the E2E PDB. At 806 the relay UE determines a PDB for the first hop. The determining of the PDB for the first hop may be as described previously. At 808 the relay UE sends, to the remote UE, information indicating the PDB for the first hop. Optionally the relay UE may start timer T in response to sending the information indicating the PDB for the first hop. As described previously, the remote UE may either accept the PDB for the first hop and maintain the E2E RB without reconfiguration or may determine to reconfigure the first hop for the E2E RB. Steps 810-814 cover the case where the remote UE accepts the PDB for the first hop without reconfiguration for the first hop, while steps 816-820 cover the case where the remote UE determines to reconfigure the first hop for the E2E RB based on the PDB for the first hop. At 810, the remote UE determines, based on the received information indicating the PDB for the first hop, that no reconfiguration of the first hop for the E2E RB is needed. For example, the remote UE may determine that no reconfiguration of the first hop for the E2E RB is needed based on determining that the PDB for the first hop is greater than or equal to the preferred PDB for the first hop and the PDB for the first hop does not cause a change to a configuration or a parameter that needs to be reconfigured to the relay UE for the first hop. At 812, based on the determination at 810, the remote UE sends an acceptance message to the relay UE. If the relay UE started timer T when sending the information at 808, then the relay UE may stop timer T when the acceptance message is received from the remote UE. At 814, the relay UE sends, to the peer remote UE, a SL RRC Reconfiguration message comprising one or more updated configurations or parameters for the packet transmissions of the end-to-end radio bearer over the second hop. The one or more updated configurations or parameters for the packet transmissions of the end-to-end radio bearer over the second hop may be based, at least in part, on the PDB for the first hop and therefore the remaining PDB of the E2E PDB for the second hop. For example, the SL RRC Reconfiguration message may comprise updated configurations of the E2E RB and / or the second hop RLC channel associated with the E2E RB. It is noted that 814 is optional and needed only if the PDB for the first hop and therefore the remaining PDB of the E2E PDB for the second hop for the E2E RB causes this reconfiguration of the second hop. At 816 the remote UE determines, based on the received information indicating the PDB for the first hop, that reconfiguration of the first hop for the E2E RB is needed. For example, the remote UE may determine that reconfiguration of the first hop for the E2E RB is needed based on determining that the PDB for the first hop is less than the preferred PDB for the first hop. For further example, the remote UE may determine that reconfiguration of the first hop for the E2E RB is needed based on determining that the PDB for the first hop is greater than or equal to the preferred PDB for the first hop but the PDB for the first hop does cause a change to one or more configurations or parameters that needs to be reconfigured to the relay UE for the first hop. At 818 the remote UE sends, to the relay UE, a SL RRC Reconfiguration message, for example as described previously. In some examples the SL RRC Reconfiguration message may comprise an update PDB for the first hop (e.g., UpdateThreshlstHopPDB) for the E2E RB as described previously. If the relay UE started timer T when sending the information at 808, then the relay UE may stop timer T when the SL RRC Reconfiguration message is received from the remote UE. At 820 the relay UE sends, to the peer remote UE, a SL RRC Reconfiguration message comprising one or more updated configurations or parameters for the packet transmissions of the end-to-end radio bearer over the second hop. The one or more updated configurations or parameters for the packet transmissions of the end-to-end radio bearer over the second hop may be based, at least in part, on the PDB for the first hop and therefore the remaining PDB of the E2E PDB for the second hop. For example, the SL RRC Reconfiguration message may comprise updated configurations of the E2E RB and / or the second hop RLC channel associated with the E2E RB. It is noted that 820 is optional and needed only if the PDB for the first hop and therefore the remaining PDB of the E2E PDB for the second hop for the E2E RB causes this reconfiguration of the second hop. Reference is made to FIG. 9, which illustrates an example of failure QoS split operation in which the remote UE initiates a new QoS split for an existing E2E RB due to a change in conditions on the first hop. In this example, the relay UE determines that the indicated preferred PDB for the first hop is not affordable to the relay UE to serve and therefore the relay UE stops serving the E2E RB. Thus the relay UE sets the first-hop PDB to zero in the QoS split indication sent to the remote UE in order to indicate to the remote UE that the relay UE is to stop serving the E2E RB. At 900 the remote UE, relay UE, and peer remote UE establish a SL relay connection for E2E communication between the remote UE and peer remote UE via the relay UE, including an E2E RB mapped on a first hop RLC channel and a second hop RLC channel, for example as described in relation to FIG. 5. Thus, all the relevant current configurations of the E2E connection, first hop and second hop and parameters (such as the preferred PDB for the first hop or the update PDB for the first hop) for the existing E2E RB are in place. At 902 the remote UE determines to initiate a new QoS split for the E2E RB. This may for example be due to determining a change in one or more conditions associated with the first hop as described previously. At 904 the remote UE sends, to the relay UE, a request for a split of an E2E PDB associated with the E2E RB. The request may be as described previously - for example the request may comprise the preferred PDB for the first hop or the update PDB for the first hop, and optionally an identifier of the E2E RB and / or the E2E PDB. At 906 the relay UE determines that a PDB for the first hop meeting the preferred PDB for the first hop (e.g., either signalled in MinRequiredlstHopPDB or an UpdateThreslstHopPDB) is not affordable to the relay UE. The relay UE may therefore determine to stop serving the E2E RB based on determining that the PDB for the first hop meeting the preferred PDB for the first hopis not affordable to the relay UE. At 908, the relay UE sends, to the remote UE, information indicating the PDB for the first hop, where the value of the first hop PDB is set to zero. As explained previously, setting the PDB for the first hop to zero may be an indication that the relay UE cannot afford to meet the preferred PDB for the first hop and will therefore stop serving the E2E RB. At 910 the relay UE, having determined to stop serving the E2E RB, stops serving the E2E RB. At 912, the remote UE, based on the received the information at 908, determines to release the E2E RB. At 914, the remote UE sends a sidelink RRC reconfiguration message to the peer remote UE. The sidelink RRC reconfiguration message may indicate respectively to the peer remote UE to release the E2E RB. Reference is made to FIG. 10, which illustrates an example of successful QoS split operation in which the relay UE determines a new QoS split for an existing E2E RB due to a change in conditions on the second hop. In this example, the relay UE may indicate the new QoS split to the remote UE; or the relay UE may skip indicating the new QoS split to remote UE when the new QoS split exceeds the preferred PDB for the first hop (e.g., indicated in either MinRequiredlstHopPDB or UpdateThreslstHopPDB). At 1000 the remote UE, relay UE, and peer remote UE establish a SL relay connection for E2E communication between the remote UE and peer remote UE via the relay UE, including an E2E RB mapped on a first hop RLC channel and a second hop RLC channel, for example as described in relation to FIG. 5. Thus, all the relevant current configurations of the E2E connection, first hop and second hop and parameters (such as the preferred PDB for the first hop or the update PDB for the first hop) for the existing E2E RB are in place. At 1002 the relay UE determines, based on one or more conditions on the second hop, a new QoS split of the E2E PDB for the E2E RB, for example as described previously. The new QoS split may be such that the new QoS split exceeds the preferred PDB for the first hop- that is to say the PDB for the first hop determined by the relay UE at 1002 may be above the preferred PDB for the first hop. In some examples the relay UE may inform the remote UE of the new PDB for the first hop and perform steps 1004-1010, which correspond to the operations performed in steps 808-814. Alternatively to steps 1004-1010, at 1012 the relay UE may determine that the new QoS split or, more particularly, the new PDB for the first hop exceeds the preferred PDB for the first hop and remains in the same PDB range with the current PDB (e.g., indicated in MinRequiredlstHopPDB and UpdateThreslstHopPDB) and may therefore determine to skip notifying the remote UE. In other words, the relay UE may determine that the remote UE would accept the QoS split without any reconfiguration, and may therefore skip notifying the remote UE, thereby saving time and signalling resources. The relay UE may then proceed with step 1014, which corresponds to step 814. Reference is made to FIG. 11, which illustrates an example of a successful QoS split operation in which the relay UE initiates a new QoS split for an existing E2E RB due to a change in conditions on the second hop. In this example, the new QoS split results in the first hop PDB below the current preferred PDB for the first hop of the E2E RB that has been indicated to the relay UE. In some examples the preferred PDB for the first hop available at the relay UE may be out-of-date. The remote UE may in some examples accept the new QoS split when the preferred first hop PDB has changed such that the new first hop PDB (indicated by the relay UE) meets the updated preferred first hop PDB. In some examples the remote UE may indicate the updated preferred PDB for the first hop in the acceptance message. Thus, the overall operation may still be considered as successful. At 1100 the remote UE, relay UE, and peer remote UE establish a SL relay connection for E2E communication between the remote UE and peer remote UE via the relay UE, including an E2E RB mapped on a first hop RLC channel and a second hop RLC channel, for example as described in relation to FIG. 5. Thus, all the relevant current configurations of the E2E connection, first hop and second hop and parameters (such as the preferred PDB for the first hop or the update PDB for the first hop) for the existing E2E RB are in place. At 1102 the relay UE determines, based on one or more conditions on the second hop, a new QoS split of the E2E PDB for the E2E RB, for example as described previously. The new QoS split may be such that the new QoS split is below the preferred PDB for the first hop available at the relay UE. At 1104 the relay UE sends, to the remote UE, information indicating the PDB for the first hop. Optionally the relay UE may start timer T in response to sending the information indicating the PDB for the first hop. At 1106, the remote UE determines an updated preferred PDB for the first hop. At 1108, based on the updated preferred PDB for the first hop (determined at 1106) and the information indicating the PDB for the first hop (received at 1104), the remote UE determines no reconfiguration of the first hop for the E2E RB is needed. In this case, the PDB for the first hop is larger than or equal to the updated preferred PDB for the first hop. At 1110, based on the determination at 1108, the remote UE sends an acceptance message to the relay UE. If the relay UE started timer T when sending the information at 1104, then the relay UE may stop timer T when the acceptance message is received from the remote UE. The acceptance message comprises the updated preferred PDB for the first hop. At 1112, the relay UE updates the preferred PDB for the first hop stored at the relay UE based on the updated preferred PDB for the first hop comprised in the acceptance message received at 1110. Reference is made to FIG. 12, which illustrates an example of an unsuccessful QoS split operation in which the relay UE initiates a new QoS split for an existing E2E RB due to a change in conditions on the second hop. In this example, the new QoS split results in the first hop PDB being below the current preferred PDB for the first hop of the E2E RB that has been indicated to the relay UE (as was the case in the example described above in relation to FIG. 11); however in this example the remote UE cannot accept the new QoS split and so releases the E2E RB. Thus, the overall operation is considered as unsuccessful. At 1200, the remote UE, relay UE, and peer remote UE establish a SL relay connection for E2E communication between the remote UE and peer remote UE via the relay UE, including an E2E RB mapped on a first hop RLC channel and a second hop RLC channel, for example as described in relation to FIG. 5. Thus, all the relevant current configurations of the E2E connection, first hop and second hop and parameters (such as the preferred PDB for the first hop or the update PDB for the first hop) for the existing E2E RB are in place. At 1202 the relay UE determines, based on one or more conditions on the second hop, a new QoS split of the E2E PDB for the E2E RB, for example as described previously. The new QoS split may be such that the new QoS split is below the preferred PDB for the first hop available at the relay UE. At 1204 the relay UE sends, to the remote UE, information indicating the PDB for the first hop. Optionally the relay UE may start timer T in response to sending the information indicating the PDB for the first hop. At 1206 the remote UE determines, based on the received information indicating the PDB for the first hop, that the indicated PDB is not acceptable to the remote UE. The remote UE therefore determines to release the E2E RB. At 1208 the remote UE sends, to the relay UE, a SL RRC Reconfiguration message, for example as described previously. The SL RRC Reconfiguration message indicates the release of the E2E RB. If the relay UE started timer T when sending the information at 808, then the relay UE may stop timer T when the SL RRC Reconfiguration message is received from the remote UE. At 1210 the relay UE stops serving the E2E RB. At 1212 the remote UE sends a sidelink RRC reconfiguration message to the peer remote UE. The sidelink RRC reconfiguration message may indicate to the peer remote UE to release the E2E RB. Examples have been described whereby an end-to-end packet delay budget of an end-to-end radio bearer between a transmitter UE and a receiver UE is split into a packet delay budget for a first hop between the transmitter UE and a relay UE, and a second hop between the relay UE and the receiver UE. The relay UE may determine the packet delay budget for the second hop, either based on a preferred packet delay budget for the first hop determined by the transmitter UE based on one or more conditions of the first hop and subsequently signalled to the relay UE or based on one or more conditions of the second hop. Examples may therefore provide mechanisms to enable and facilitate QoS split and L2 reconfiguration adapted to conditions of the first hop and second hop. The QoS split may be adapted dynamically based on changes in radio conditions on the first hop or second hop, and may therefore help optimize the sidelink connection between the transmitter UE and receiver UE. While examples have been described with respect to the split of an end-to-end packet delay budget of an end-to-end radio bearer between a transmitter UE and receiver UE, it should be understood that in some examples a different end-to-end QoS parameter may be similarly split following the examples described herein. For example, packet error rate for the end-to-end radio bearer may also be split for the first hop and second hop. In some examples there is provided a transmitter user equipment comprising means for: determining, based on one or more conditions of a first hop, a preferred packet delay budget for the first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and a relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; sending, to the relay user equipment, a request for a split of an end-to-end packet delay budget associated with the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment, wherein the request comprises the determined preferred packet delay budget for the first hop; receiving, from the relay user equipment, information indicating a packet delay budget for the first hop for the end-to-end radio bearer; and based on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either: accepting the packet delay budget for the first hop and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; or reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. In some examples there is provided a transmitter user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the transmitter user equipment at least to: determine, based on one or more conditions of a first hop, a preferred packet delay budget for the first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and a relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; send, to the relay user equipment, a request for a split of an end-to-end packet delay budget associated with the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment, wherein the request comprises the determined preferred packet delay budget for the first hop; receive, from the relay user equipment, information indicating a packet delay budget for the first hop for the end-to-end radio bearer; and based on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either: accept the packet delay budget for the first hop and maintain the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; or reconfigure the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. In some examples there is provided a relay user equipment comprising means for: receiving, from a transmitter user equipment, a request for a split of an end-to-end packet delay budget associated with an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the request comprises a preferred packet delay budget for a first hop, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; determining, based on the request, a packet delay budget for the first hop for the end-to-end radio bearer; and sending, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop for the end-to-end radio bearer. In some examples there is provided a relay user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the relay user equipment at least to: receive, from a transmitter user equipment, a request for a split of an end-to-end packet delay budget associated with an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the request comprises a preferred packet delay budget for a first hop, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; determine, based on the request, a packet delay budget for the first hop for the end-to-end radio bearer; and send, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop for the end-to-end radio bearer. In some examples there is provided a transmitter user equipment comprising means for: receiving, from a relay user equipment, information indicating a packet delay budget for a first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; and based on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either: accepting the packet delay budget for the first hop and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; or reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. In some examples there is provided a transmitter user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the transmitter user equipment at least to: receive, from a relay user equipment, information indicating a packet delay budget for a first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; and based on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either: accept the packet delay budget for the first hop and maintain the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; or reconfigure the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment. In some examples there is provided a relay user equipment comprising means for: determining a change in conditions of a second hop for an end-to-end radio bearer between a transmitter user equipment and a receiver user equipment, wherein the second hop is a hop between the relay user equipment and the receiver user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; determining, based on the determined change in conditions, a packet delay budget for a first hop for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in the user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; and sending, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop. In some examples there is provided a relay user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the relay user equipment at least to: determine a change in conditions of a second hop for an end-to-end radio bearer between a transmitter user equipment and a receiver user equipment, wherein the second hop is a hop between the relay user equipment and the receiver user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; determine, based on the determined change in conditions, a packet delay budget for a first hop for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in the user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment; and send, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop. FIG. 13 shows a schematic representation of non-volatile memory media 1300a (e.g., computer disc (CD) or digital versatile disc (DVD)) and 1300b (e.g. universal serial bus (USB) memory stick) storing instructions and / or parameters 1302 which when executed by a processor allow the processor to perform one or more of the steps of the method of FIG. 7. It is understood that references in the above to various network functions (e.g., to an AMF, an SMF, TNF 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. 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, 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 (c) hardware circuit(s) and or processor(s), such as a microprocessor(s) or a portion of a microprocessor(s), that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.” This definition of circuitry applies to all uses of this term 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 FIG.s 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, by way 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. A transmitter user equipment comprising means for:determining, based on one or more conditions of a first hop, a preferred packet delay budget for the first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and a relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment;sending, to the relay user equipment, a request for a split of an end-to-end packet delay budget associated with the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment, wherein the request comprises the determined preferred packet delay budget for the first hop;receiving, from the relay user equipment, information indicating a packet delay budget for the first hop for the end-to-end radio bearer; andbased on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either:accepting the packet delay budget for the first hop and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; orreconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment.

2. The transmitter user equipment of claim 1, wherein the preferred packet delay budget for the first hop comprises a minimum required packet delay budget for the first hop.

3. The transmitter user equipment of claim 1 or 2, wherein the request for the split of the end-to-end packet delay budget further comprises an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment,wherein the packet delay budget for the first hop is further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment.

4. The transmitter user equipment of any preceding claim, wherein accepting the packet delay budget comprises:determining, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed;in response to determining that no reconfiguration of the first hop is needed, sending an acceptance message to the relay user equipment accepting the packet delay budget for the first hop; andmaintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment.

5. The transmitter user equipment of claim 4, wherein determining, based on the packet delay budget for the first hop, that no reconfiguration of the first hop is needed, comprises determining that the packet delay budget for the first hop is greater than or equal to the preferred packet delay budget for the first hop.

6. The transmitter user equipment of any of claims 1 to 3, wherein reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment comprises:determining, based on the packet delay budget for the first hop, that a reconfiguration of the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment is needed;in response to determining that a reconfiguration of the first hop is needed, reconfiguring one or more configurations or parameters for packet transmission of the end-to-end radio bearer over the first hop.

7. The transmitter user equipment of claim 6, wherein determining, based on the packet delay budget for the first hop, that a reconfiguration of the first hop is needed comprises determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop.

8. The transmitter user equipment of claim 6 or 7, wherein reconfiguring one or more parameters for packet transmission of the end-to-end radio bearer over the first hop comprises:sending, to the relay user equipment, a sidelink reconfiguration message comprising one or more updated configurations or parameters for packet transmission of the end-to-end radio bearer over the first hop.

9. The transmitter user equipment of claim 8, wherein the means is further for: determining an updated preferred packet delay budget for the first hop,wherein the sidelink reconfiguration message further comprises the updated preferred packet delay budget for the first hop.

10. The transmitter user equipment of claim 7, wherein reconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment comprises releasing the end-to-end radio bearer between the transmitter user equipment and receiver user equipment.

11. A relay user equipment comprising means for:receiving, from a transmitter user equipment, a request for a split of an end-to-end packet delay budget associated with an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the request comprises a preferred packet delay budget for a first hop, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment;determining, based on the request, a packet delay budget for the first hop for the end-to-end radio bearer; andsending, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop for the end-to-end radio bearer.

12. The relay user equipment of claim 11, wherein the preferred packet delay budget for the first hop comprises a minimum required packet delay budget for the first hop.

13. The relay user equipment of claim 11 or 12, wherein the request for the split of the end-to-end packet delay budget further comprises an end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment via the relay user equipment,wherein determining the packet delay budget for the first hop is further based on the end-to-end packet delay budget for the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment.

14. The relay user equipment of any of claims 11 to 13, wherein the means is further for:receiving, from the transmitter user equipment, an acceptance message accepting the packet delay budget for the first hop; andmaintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment.

15. The relay user equipment of any of claims 11 to 13, wherein the means is further for:receiving, from the transmitter user equipment, a first sidelink reconfiguration message comprising one or more updated configurations or parameters for packet transmission of the end-to-end radio bearer over the first hop; andsending, to the receiver user equipment, a second sidelink reconfiguration message comprising one or more updated configurations or parameters for packet transmissions of the end-to-end radio bearer over a second hop, wherein the second hop is a hop between the relay user equipment and the receiver user equipment in the user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment.

16. The relay user equipment of claim 15, wherein the first sidelink reconfiguration message further comprises an updated preferred packet delay budget for the first hop.

17. The relay user equipment of claim 16, wherein the means is for:determining that the packet delay budget for the first hop is less than the preferred packet delay budget for the first hop;wherein the sending comprises sending the information indicating the determined packet delay budget for the first hop when:the determined packet delay budget for the first hop is above the preferred packet delay budget for the first hop minus a configured offset; and / orthe determined packet delay budget for the first hop is affordable to the relay user equipment; and / orthe preferred packet delay budget for the first hop has been applied for at least a preconfigured time duration.

18. The relay user equipment of any of claims 11 to 17, wherein the means is further for: responsive to sending the information, starting a timer; andif the acceptance message or the first sidelink reconfiguration message is received during the duration of the timer, stopping the timer; orif the acceptance message or the first sidelink reconfiguration message is not received during the duration of the timer, terminating the end-to-end radio bearer upon expiry of the timer.

19. The relay user equipment of any of claims 11 to 13, wherein determining the packet delay budget for the first hop comprises:determining that the preferred packet delay budget for the first hop is unaffordable;setting the packet delay budget for the first hop to zero; andstopping serving the end-to-end radio bearer between the transmitter user equipment and a receiver user equipment.

20. A transmitter user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the transmitter user equipment at least to:determine, based on one or more conditions of a first hop, a preferred packet delay budget for the first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and a relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment;send, to the relay user equipment, a request for a split of an end-to-end packet delay budget associated with the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment, wherein the request comprises the determined preferred packet delay budget for the first hop;receive, from the relay user equipment, information indicating a packet delay budget for the first hop for the end-to-end radio bearer; andbased on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either:accept the packet delay budget for the first hop and maintain the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; orreconfigure the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment.

21. A relay user equipment comprising at least one processor and at least one memory storing instructions that, when executed by the at least one processor, cause the relay user equipment at least to:receive, from a transmitter user equipment, a request for a split of an end-to-end packet delay budget associated with an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the request comprises a preferred packet delay budget for a first hop, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relayconnection between the transmitter user equipment and the receiver user equipment via the relay user equipment;determine, based on the request, a packet delay budget for the first hop for the end-to-end radio bearer; andsend, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop for the end-to-end radio bearer.

22. A method performed by a transmitter user equipment, the method comprising: determining, based on one or more conditions of a first hop, a preferred packet delay budget for the first hop for an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the first hop is a hop between the transmitter user equipment and a relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment;sending, to the relay user equipment, a request for a split of an end-to-end packet delay budget associated with the end-to-end radio bearer between the transmitter user equipment and the receiver user equipment, wherein the request comprises the determined preferred packet delay budget for the first hop;receiving, from the relay user equipment, information indicating a packet delay budget for the first hop for the end-to-end radio bearer; andbased on the received information indicating the packet delay budget for the first hop for the end-to-end radio bearer, either:accepting the packet delay budget for the first hop and maintaining the end-to-end radio bearer between the transmitter user equipment and receiver user equipment via the relay user equipment; orreconfiguring the first hop for the end-to-end radio bearer between the transmitter user equipment and receiver user equipment.

23. A method performed by a relay user equipment, the method comprising: receiving, from a transmitter user equipment, a request for a split of an end-to-end packet delay budget associated with an end-to-end radio bearer between the transmitter user equipment and a receiver user equipment, wherein the request comprises a preferred packet delay budget for a first hop, wherein the first hop is a hop between the transmitter user equipment and the relay user equipment in a user equipment to user equipment relay connection between the transmitter user equipment and the receiver user equipment via the relay user equipment;determining, based on the request, a packet delay budget for the first hop for the end-to-end radio bearer; andsending, to the transmitter user equipment, information indicating the determined packet delay budget for the first hop for the end-to-end radio bearer.

Images