Embodiments of the present disclosure relate to methods, devices, apparatuses and computer readable storage medium of groupcast for sidelink communication. In example embodiments, at a leader device in a group of devices, an orthogonal sequence and cover code is selected from a first set of orthogonal sequences and a first set of orthogonal cover codes. The first set of orthogonal sequences and the first set of orthogonal cover codes are used for acknowledgement feedback in the group. An indication of the selected orthogonal sequence and cover code is sent to a first member device of a plurality of member devices in the group.

According to some embodiments, a method for use in a user equipment (UE) of managing a listen-before-talk (LBT) contention window size comprises receiving scheduling for a current burst of contiguous uplink subframes. For each subframe the scheduling comprises an associated hybrid automatic repeat request (HARQ) process identifier and a new data indicator (NDI). The method determines a reference subframe based on a previously-scheduled burst of contiguous uplink subframes. The reference subframe is associated with a reference HARQ process identifier. When the UE determines the HARQ process identifier associated with a subframe of the current scheduled burst of contiguous uplink subframes matches the reference HARQ process identifier and the NDI indicates new data, the method resets the LBT contention window. When the reference HARQ process identifier matches, but the associated NDI indicates a retransmission, or the HARQ process identifier does not match, the method increments the LBT contention window.

Methods and apparatuses are disclosed for an energy detection indicator. In one embodiment, a method for a network node includes performing energy detection on assigned resources corresponding to a configured uplink grant for a wireless device, WD; and based on a level of the detected energy, one of: sending an energy 5detection indication corresponding to the assigned resources associated with the configured uplink grant; and demodulating and decoding a transport block associated with the configured uplink grant. In another embodiment, a method for a wireless device includes receiving an energy detection indication corresponding to assigned resources associated with a configured uplink grant; and determining whether to 10perform an uplink retransmission based at least in part on the received energy detection indication.

Provided are a method in which a terminal determines whether or not information is successfully transmitted to a plurality of terminals in a group in a wireless communication system, and a device supporting same. The method can comprise the steps of: transmitting the information to a plurality of terminals in the group; receiving zero or one or more feedback information items on a first resource in response to the transmitted information; and determining whether or not the information is successfully transmitted to the plurality of terminals in the group, on the basis of power measured in the first resource and power measured in a second resource.

Systems, methods, and instrumentalities are disclosed for narrowband (NB) LTE operation. A WTRU may receive a first downlink data transmission, for example, via a physical downlink shared channel (PDSCH). The WTRU may determine to send a hybrid automatic repeat request (HARQ) acknowledgment (ACK) in response to receipt of the first downlink data transmission. The WTRU may transmit a first uplink reference signal. The WTRU may indicate the HARQ-ACK using a first cyclic shift index that is applied to the first uplink reference signal. The WTRU may determine to send a HARQ negative ACK (HARQ-NACK), for example, on a condition that a second downlink data transmission is not correctly received. The WTRU may send a second uplink reference signal. The WTRU may indicate the HARQ-NACK using a second cyclic shift that is applied to the second uplink reference signal.

When a plurality of terminals share the same resources in a wireless communication system, and when control information such as acknowledgement/negative acknowledgement (ACK/NAK) information or scheduling information is transmitted, a method of efficiently performing code division multiplexing (CDM) is required to distinguish the plurality of terminals. In particular, it is necessary to develop a method by which a code sequence of CDM can be selected and used according to each cell condition. Provided is a method of forming a signal in a wireless communication system in which a plurality of terminals commonly share frequency and time resources. The method includes the operations of receiving condition information in a cell; selecting one of a plurality of time domain orthogonal sequences having different lengths, according to the condition information; and allocating the selected time domain orthogonal sequence to a control signal symbol block.

Proposed is a method of performing wireless communication by a first apparatus. The method may include receiving one or more reference signals, each generated by one or more apparatuses, from the one or more apparatuses, and determining discontinuous detection (DTX) related to one or more second apparatuses 200 among the one or more apparatuses based on the one or more reference signals, and transmitting hybrid automatic repeat request (HARQ) feedback to the one or more second apparatuses 200.

Acknowledgement feedback is conveyed to a network node for unicast and multicast transmissions received by a wireless device. The wireless device configures uplink control channel resources responsive to an uplink channel format indicated by an uplink channel format indicator. Each possible ACK or NAK combination for the unicast and multicast transmissions maps to a different cyclic shift of a base sequence defined according to the uplink control channel format. The wireless device receives a unicast transmission and a multicast transmission. Further, when in a joint acknowledgement mode, the wireless device configures acknowledgement feedback for the received unicast and multicast transmissions according to the cyclic shift mapping and jointly transmits the acknowledgement feedback for both the received unicast transmission and the received multicast transmission to the network node in an acknowledgement time slot.

A communications system is described in which user devices are allocated sub-carriers on which to transmit uplink data to a base station. ACK/NACK messages for the data transmitted on the uplink are then transmitted by the base station on sub-carriers that depend on the sub-carriers used to carry the uplink data. A direct mapping function is preferably used to determine the sub-carriers to be used for the ACK/NACK messages from the uplink sub-carriers. In another embodiment, the ACK/NACK messages are transmitted to the user devices on sub-carriers that are previously identified to the user devices, preferably by transmitting one or more index values to the user device in a control channel thereof.

Some embodiments of the present disclosure provide a user equipment (UE) having active device components and passive device components. Responsive to receiving downlink (DL) transmissions in time division duplexing (TDD) mode, the active device components perform DL decoding while the passive device components perform passive transmission of ACK/NACK data. Such passive transmission may involve encoding the ACK/NACK data in an altered version of received radio frequency (RF) signals and using so-called backscatter communications to reflect the received RF signals, with alteration, using the same frequency resources used to receive the DL transmissions.