BACKGROUND

Mobile communications are in continuous evolution and is already at the doorstep of its fifth incarnation—5G. 5G network may be built on flexible radio access technologies. As these new technologies emerge, challenges arise in determining how to support a wide variety of usage cases with differing characteristics.

SUMMARY

Systems, methods and instrumentalities are disclosed herein for transmitting uplink data from a wireless transmit/receive unit (WTRU) to a network. The uplink data may include an uplink data unit (e.g., an uplink data packet), and the transmission of the uplink data unit may be performed in a manner that satisfies a specific quality of service (QoS) requirement. The QoS requirement may be a timing requirement. For example, the QoS requirement may be that the uplink data unit be transmitted with relatively low latency.

The WTRU may maintain a time-to-live (TTL) parameter to monitor the transmission latency of the uplink data unit. For example, the value of the TTL parameter may be reflective of an amount of time elapsed since the uplink data unit became available for transmission and/or an amount of time remaining before the uplink data unit is supposed to be successfully transmitted. The WTRU may determine, based on the QoS requirement, a threshold value for the TTL parameter, attempt to transmit the uplink data unit using a first transmission mode, and determine that the value of the TTL parameter has reached a threshold value before a successful transmission can be accomplished. The WTRU may then try to transmit the uplink data unit using a second transmission mode, for example until the TTL parameter reaches expiration.

The second transmission mode may differ from the first transmission mode in one or more aspects. For example, the WTRU may transmit the uplink data unit in the second transmission mode using a pre-configured set of resources. The WTRU may receive such preconfigured resources, for example from a network. The network may have reserved the preconfigured resources for transmissions characterized by a particular QoS requirement, such as the QoS requirement associated with the pending uplink data unit. The network may specify that the pre-configured resources are to be shared by multiple WTRUs.

The WTRU may receive the pre-configured resources when the WTRU initially registers with the network. Alternatively or additionally, the WTRU may receive the pre-configured resources via dedicated signaling from the network (e.g., after the WTRU has already registered with the network). The WTRU may gain access to the pre-configured set of resources through an uplink transmission to the network. The uplink transmission may indicate a time at which the WTRU desires to use the pre-configured resources, for example. The WTRU may receive an acknowledgement from the network in response to the uplink transmission.

The WTRU may, in the second transmission mode, send uplink control information (UCI) to the network. The UCI may include a request for resources. The UCI may indicate the QoS requirement associated with the uplink data unit, or a numerology of the uplink data unit. The WTRU may receive a grant from the network in response to the UCI. The grant may indicate which resources the WTRU can use in the second transmission mode. Additionally or alternatively, the grant may specify a spectrum operation mode (SOM) or a transport channel that the WTRU can use in the second transmission mode. For example, the grant may specify a numerology and/or a waveform that the WTRU can use in the second transmission mode.

The WTRU may, in the second transmission mode, interrupt an existing hybrid automatic repeat request (HARQ) process to transmit the uplink data unit.

