In an exemplary aspect, a digital routing unit (DRU) may have two signal streams that require synchronization therebetween. To provide such synchronization, the DRU may insert a frame counter into signals being sent to remote units. If both signals are sent to the same remote unit, the remote unit may synchronize by matching frames having the same frame counter. The remote unit may also determine a time of arrival difference between frames having the same frame counter and buffer frames accordingly to assist in synchronizing the frames. If the two signals are sent to different remote units, the remote units may send the counter back to the DRU, which can calculate a round trip time difference and insert a phase offset in future transmissions to assist in synchronization. In this fashion, the frames may be synchronized to assist in meeting the relevant fourth generation (4G) or fifth generation (5G) requirements.

A method for selecting best radio signal in air traffic control includes: determining a respective latency of at least two receiving channels, wherein each receiving channel is provided between a corresponding receiver and a measurement and analysis module; measuring a respective arrival time of at least two radio signals received via the at least two receiving channels by the measurement and analysis module; determining the delay time between the at least two radio signals based on their arrival times; aligning the at least two radio signals with each other by taking the delay time determined into account, thereby obtaining at least two aligned signals; determining the quality of the at least two aligned signals; and switching to the receiving channel that processes the respective radio signal with the best quality determined. Further, an air traffic control system for selecting best radio signal is described.

An apparatus comprises a sampling circuit configured to sample transmit and receive signals of a first radio node to be transmitted to or received from a second radio node. Transmit-side and receive-side envelope detectors are configured to produce transmit-side and receive-side envelope signals based on sampled transmit and receive signals. A transmit-side time measurement unit is configured to generate, based on the transmit-side envelope signal, a transmit-side marker signal based on a pre-defined transmit-side threshold, measure at least one first time delay between at least one time start pulse and at least one marker of the transmit-side marker signal and store to a memory and/or output said at least one first time delay. A receive-side time measurement unit is configured to implement the corresponding functionalities as described for the transmit-side time measurement unit in the receive-side.

Systems and methods pertain to operating a receiver of wireless signals such as Bluetooth or Bluetooth Low Energy (BLE) signals. A correlator is provided to correlate a wireless signal received by the receiver with a device identifier corresponding to a wanted device from which the receiver wants to receive wireless signals, to generate a correlator output. An adaptive acquisition threshold generator generates an adaptive acquisition threshold based on a signal strength of the wireless signal, and a comparator is used to determine if the wireless signal is a wanted signal intended for the receiver, based on a comparison of the correlator output with the adaptive acquisition threshold.

A method for estimating a time-of-arrival of a packet received by a receiver includes storing a reference bit-pattern and receiving a plurality of samples in a samples-buffer. In a bit-pattern detector, a matching group of samples having a bit-pattern which matches the reference bit-pattern is identified. In a correlator, a group of three correlation values is determined from the matching group of samples, including a local maximum correlation value, P0, an immediately preceding correlation value, Pm, and an immediately succeeding correlation value Pp. In an estimation unit, a polynomial function f(δ) of the difference, δ, between Pm and Pp is used to estimate a timing offset T.sub.frac, between the local maximum correlation value and a correlation peak. The time-of-arrival is estimated from a time of the local maximum correlation value P0, and T.sub.frac.

A method for estimating a time-of-arrival of a packet received by a receiver includes storing a reference bit-pattern and receiving a plurality of samples in a samples-buffer. In a bit-pattern detector, a matching group of samples having a bit-pattern which matches the reference bit-pattern is identified. In a correlator, a group of three correlation values is determined from the matching group of samples, including a local maximum correlation value, P0, an immediately preceding correlation value, Pm, and an immediately succeeding correlation value Pp. In an estimation unit, a polynomial function f(δ) of the difference, δ, between Pm and Pp is used to estimate a timing offset T.sub.frac, between the local maximum correlation value and a correlation peak. The time-of-arrival is estimated from a time of the local maximum correlation value P0, and T.sub.frac.

A method determining a timing of an uplink signal includes receiving timing information associated with an uplink signal and a numerology of the uplink signal, wherein the timing information is used to determine a reference time of the uplink signal received from a user equipment (UE), receiving, from the UE, the uplink signal, wherein the receiving is in accordance with the timing information and the numerology of the uplink signal, and measuring an uplink relative time of arrival in accordance with the received uplink signal and the reference time of the uplink signal.

A UE may determine a frame structure for narrowband communications, the frame structure corresponding to one frame structure from a group of TDD frame structures of different downlink and uplink subframe configurations. The UE receives configuration information indicating a first carrier to monitor for a BCH and/or a SIB1. Then, the UE receives a PSS, an SSS, and the BCH and/or the SIB1 using the frame structure determined for the narrowband communications. The first carrier that is used to receive the BCH and/or the SIB1 may be different from a second carrier used to receive one or more of the PSS or the SSS.

A method for selecting best radio signal in air traffic control includes: determining a respective latency of at least two receiving channels, wherein each receiving channel is provided between a corresponding receiver and a measurement and analysis module; measuring a respective arrival time of at least two radio signals received via the at least two receiving channels by the measurement and analysis module; determining the delay time between the at least two radio signals based on their arrival times; aligning the at least two radio signals with each other by taking the delay time determined into account, thereby obtaining at least two aligned signals; determining the quality of the at least two aligned signals; and switching to the receiving channel that processes the respective radio signal with the best quality determined. Further, an air traffic control system for selecting best radio signal is described.

There is a need to support narrowband TDD frame structure for narrowband communications. The present disclosure provides a solution by supporting one or more narrowband TDD frame structure(s) for narrowband communications. In an aspect of the disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may determine a narrowband communication frame structure comprising a FDD mode or a TDD mode and a particular TDD frame structure for narrowband communications from a group of narrowband TDD frame structures. The apparatus may determine a periodicity, subframe number, and transmission sequence associated with a SSS based at least in part on the narrowband TDD frame structure. The apparatus may transmit the SSS using the narrowband TDD frame structure determined for the narrowband communications. In one aspect, the SSS may be transmitted in a same subframe within a frame and at a periodicity of 2 or more frames.