Beam-scan time indicator
The present disclosure relates to transmitting synchronization signals and in particular to so called beam sweep. In particular the disclosure relates to methods for providing synchronization using synchronization sequences that are transmitted at different points in time. The disclosure also relates to corresponding devices and computer programs. A method in a network node, for transmitting synchronization sequences of a synchronization signal to one or more receiving wireless devices, comprises determining multiple synchronization sequences, such that each synchronization sequence comprises a respective timing indication, whereby each synchronization sequence enables determination of a time of an event in a receiving wireless device and transmitting the synchronization sequences to the one or more wireless devices, at different points in time.
1 . A method implemented by a network node of a wireless communication network, the method comprising:
transmitting respective synchronization sequences in respective beams transmitted in a beam sweep by the network node at different transmission times, the synchronization sequences for use by wireless devices in gaining time and frequency synchronization with the wireless communication network; and
wherein each synchronization sequence has an index that depends on the transmission timing of the synchronization sequence and indicates a relative timing of a forthcoming uplink transmission occasion when the wireless devices are allowed to transmit a random access preamble, wherein the indices of the synchronization sequences form a consecutive number series.
2 . The method of claim 1 , wherein each synchronization sequence is beam specific.
3 . The method of claim 1 , wherein transmitting the respective synchronization sequences is performed during a beam sweep in which the network node transmits the respective synchronization sequences at successive transmission times, and wherein the index of each synchronization sequence depends on the transmission time within the beam sweep.
4 . The method of claim 1 , wherein two or more of the respective beams are transmitted in different directions at different times.
5 . The method of claim 1 , wherein the relative timing is a time remaining until the uplink transmission occasion.
6 . The method of claim 1 , wherein each synchronization sequence is comprised in a transmission that encodes the index of the synchronization sequence.
7 . The method of claim 1 , wherein each synchronization sequence is comprised in a synchronization transmission that includes transmission of a Physical Broadcast Channel (PBCH), and wherein the method comprises performing a plurality of synchronization transmissions sequentially during a beam sweep, where the index of each synchronization sequence indicates the position of the synchronization transmission within the plurality of synchronization transmissions.
8 . A method of operation by a wireless device with respect to a wireless communication network, the method comprising:
receiving a synchronization sequence transmitted in a beam sweep by a network node of the wireless communication network, the synchronization sequence to be used for obtaining time and frequency synchronization with the wireless communication network and being one among two or more synchronization sequences transmitted by the network node at different transmission times;
determining an index of the synchronization sequence, the index being dependent on the transmission timing of the synchronization sequence;
determining a time of a forthcoming uplink transmission occasion according to a relative timing indicated by the index, wherein the forthcoming uplink transmission occasion is when the wireless device is allowed to transmit a random access preamble, and wherein the indices of the synchronization sequences form a consecutive number series.
9 . The method of claim 8 , wherein the relative timing is a timing offset in which a time remaining until occurrence of the forthcoming uplink transmission occasion is indicated by the index.
10 . A wireless device configured for operation in a wireless communication network, the wireless device comprising:
a communication interface configured to receive transmissions from a network node of the wireless communication network; and
processing circuitry configured to:
determine an index of a synchronization sequence transmitted by the network node as one among two or more synchronization sequences transmitted at different times, the index indicating a relative timing; and
determine a time when the wireless device is allowed to transmit a random access preamble from the relative timing indicated by the index, wherein the indices of the synchronization sequences form a consecutive number series.
11 . The wireless device of claim 10 , wherein the two or more synchronization sequences are among a plurality of synchronization sequences transmitted sequentially by the network node during a beam sweep.