Systems and methods are disclosed for random access in a wireless communication system such as, e.g., a wireless communication system having a non-terrestrial (e.g., satellite-based) radio access network. Embodiments of a method performed by a wireless device and corresponding embodiments of a wireless device are disclosed. In some embodiments, a method performed by a wireless device for random access comprises performing an open-loop timing advance estimation procedure to thereby determine an open-loop timing advance estimate for an uplink between the wireless device and a base station. The method further comprises transmitting a random access preamble using the open-loop timing advance estimate. In this manner, random access can be performed even in the presence of a long propagation delay such as that present in a satellite-based radio access network. Embodiments of a method performed by a base station and corresponding embodiments of a base station are also disclosed.

The present invention provides a signal determining method and an apparatus, so as to resolve a problem, in a conventional positioning method, that a signal receiving device cannot accurately determine whether a received signal is an aggregated reference signal, and consequently, positioning fails due to a relatively large error of location information obtained by means of positioning. The method is as follows: A signal receiving device may estimate, according to a TAE between at least two subcarriers used by a signal sending device to transmit a reference signal and a reference signal sent by the signal sending device on each subcarrier, an aggregated reference signal that is sent by the signal sending device and that is obtained after carrier aggregation. After receiving a signal, the signal receiving device determines whether the signal is an aggregated reference signal sent by the signal sending device.

Methods, systems, and devices for wireless communication are described. A base station may establish a transmission gap between downlink (DL) and uplink (UL) transmissions on a shared radio frequency (RF) spectrum band using time division duplex (TDD). The gap length may be based at least in part on a maximum allowed length of a filler signal corresponding to a coverage area of the base station. To reserve the shared band, a user equipment (UE) may communicate the filler signal for a length of time that is based at least in part on the maximum allowed length and a geographic distance between the UE and the base station. UEs farther from the base station transmit the filler signal of shorter lengths before sending an UL transmission, so that the UL transmissions from different UEs arrive at the same time at the base station regardless of the geographic distance between the UEs.

Methods for determining a location of an unknown device (UD) from a plurality of known devices (KDs) are provided including receiving, at the UD, periodically broadcasted messages from each of a plurality of KDs. Corresponding arrival time stamp (T.sub.arrival-i-UD) of each periodically broadcasted message from each of the plurality of KDs are recorded. Each of the plurality of KDs are clock synchronized to a common clock source at a master device(MD). A departure time of the periodically broadcasted message from each of the plurality of KDs is known by the UD in master device time units (T.sub.depart-i-md). X, y and z coordinates of a location of each of the KDs is known by the UD. The x, y and z coordinates of an actual location of the UD is calculated using the x, y and z coordinates of each of the KDs, the recorded arrival times (T.sub.arrival-i-UD) of each of the periodically broadcasted messages from each of the plurality of KDs and the known departure times of each of the periodically broadcasted messages (T.sub.depart-i-md) from each of the plurality of KDs.

A method for discovering devices in a peer to peer (P2P) wireless communication network is described. During a search state of a first communication device, a probe request is transmitted by the first communication device on a first channel included in a plurality of channels. During the search state, a probe response transmitted by a second communication device on the first channel is received by the first communication device. In response to the probe response, a ranging exchange with the second communication device is performed by the first communication device.

Methods, systems, and devices for wireless communication are described. A base station may establish a transmission gap between downlink (DL) and uplink (UL) transmissions on a shared radio frequency (RF) spectrum band using time division duplex (TDD). A length of the gap may be based at least in part on a maximum allowed length of a filler signal corresponding to a coverage area of the base station. To reserve the shared band, a user equipment (UE) may communicate the filler signal for a length of time that is based at least in part on the maximum allowed length and a geographic distance between the UE and the base station. UEs farther from the base station transmit the filler signal of shorter lengths before sending an UL transmission, so that the UL transmissions from different UEs arrive at the same time at the base station regardless of the geographic distance between the UEs.

A user equipment (UE) receives one or more timing advance commands from a non-terrestrial network (NTN). The UE resets, after a GNSS fix, a cumulative timing advance value based on the one or more timing advance commands from the NTN and transmits an uplink transmission with a timing advance based on a self-estimated delay and the cumulative timing advance value. The UE may adjust a self-estimated delay based on at least one GNSS fix. The UE may transmit an uplink transmission with a timing advance based on the adjusted self-estimated delay and a cumulative timing advance value based on the one or more timing advance commands from the NTN.

Methods for synchronizing multiple transceivers to a single master clock are provided including broadcasting a message from a master device, the broadcasted message including a device identification number identifying the master device to at least one known device within range of the master device; receiving the message at the at least one other known device and recording a time of arrival (T.sub.arrival-kd) at the at least one other known device; repeatedly broadcasting and receiving messages and recording associated times of arrival at the at least one other known device; and applying a fit curve to the recorded arrival times to estimate a time of an event. Related devices and systems are also provided.

Systems and methods are disclosed for random access in a wireless communication system such as, e.g., a wireless communication system having a non-terrestrial (e.g., satellite-based) radio access network. Embodiments of a method performed by a wireless device and corresponding embodiments of a wireless device are disclosed. In some embodiments, a method performed by a wireless device for random access comprises performing an open-loop timing advance estimation procedure to thereby determine an open-loop timing advance estimate for an uplink between the wireless device and a base station. The method further comprises transmitting a random access preamble using the open-loop timing advance estimate. In this manner, random access can be performed even in the presence of a long propagation delay such as that present in a satellite-based radio access network. Embodiments of a method performed by a base station and corresponding embodiments of a base station are also disclosed.

The present invention provides a signal determining method and an apparatus, so as to resolve a problem, in a conventional positioning method, that a signal receiving device cannot accurately determine whether a received signal is an aggregated reference signal, and consequently, positioning fails due to a relatively large error of location information obtained by means of positioning. The method is as follows: A signal receiving device may estimate, according to a TAE between at least two subcarriers used by a signal sending device to transmit a reference signal and a reference signal sent by the signal sending device on each subcarrier, an aggregated reference signal that is sent by the signal sending device and that is obtained after carrier aggregation. After receiving a signal, the signal receiving device determines whether the signal is an aggregated reference signal sent by the signal sending device.