Systems and methods are disclosed and include a method that includes adding a training symbol prefix to an OFDM symbol frame, the prefix including a plurality of training symbols, each including N sub-symbol fields. N/2 of the sub-symbol fields are zero valued, and N/2 of the sub-symbol fields carry corresponding symbols of a N/2 sub-symbol pseudo random training symbol. A first half of the pseudo random training symbol is symmetrical to a second half of the pseudo random training symbol. An OFDM N-sub-carrier transmission carries the prefix as signal power on a first N/2 of its N sub-carriers and suppresses signal power on a second N/2 of the sub-carriers. The first N/2 and second N/2 sub-carriers alternate in the frequency domain.

The present invention discloses a detection method, a synchronization method, and a terminal for a symmetrical synchronization signal. The detection method includes the following steps: obtaining a received signal of a synchronization signal for synchronous detection, and subsequently, performing an auto-correlation calculation on the received signal twice in the time domain, where the received signal includes a first-part received signal whose length is N and a second-part received signal whose length is N.sub.CP, the first-part received signal is symmetrical about a first central point, and the second-part received signal is symmetrical about a second central point. With low complexity of calculation and good detection performance, and being insensitive to a carrier frequency offset (CFO), the present invention is particularly applicable to an Internet of Things (IoT) environment.

Determining timing of an OFDM signal comprises performing (610) an auto-correlation with a received signal, using a delay chosen to correspond to the duration of an OFDM symbol excluding the cyclic prefix, with the number of terms used in the summation in the correlation is at least as large as the smallest number of samples in any cyclic prefix of a subframe. Based on the auto-correlation, first and second correlation peaks meeting one or more predetermined detection criteria are detected (620), and evaluated to determine (630) that they are separated in time by an interval corresponding to an OFDM symbol interval. The method further comprises identifying (640), based on the two correlation peaks, one of the correlation peaks as corresponding to an OFDM symbol having a larger cyclic prefix than an adjacent OFDM symbol, and determining (650) a subframe and/or slot timing for the received signal, based on said identifying.

Provided are a preamble symbol generation method and receiving method, and a relevant frequency-domain symbol generation method and a relevant device. The method includes generating a prefix according to a partial time-domain main body signal truncated from a time-domain main body signal, generating the hyper prefix according to the entirety or a portion of the partial time-domain main body signal, and generating time-domain symbol based on at least one of the cyclic prefix. The time-domain main body signal and the hyper prefix, the preamble symbol includes the time-domain symbols.

Half tone offset may be utilized to mitigate signal distortion caused by DC bias within OFDM-based systems. In addition a cyclic prefix may be utilized within an OFDM-based system to mitigate inter-symbol-interference. Presented herein are techniques and methods to efficiently apply a cyclic prefix to an OFDM symbol with half tone offset for low power systems.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a transmitter may identify a set of resource elements on which to transmit a reference signal based at least in part on a numerology being used by the transmitter and at least one of a maximum system numerology or a minimum system numerology; and transmit the reference signal on the identified set of resource elements. In some aspects, a receiver may identify a set of resource elements from which to obtain a reference signal based at least in part on a numerology being used by the receiver and at least one of a maximum system numerology or a minimum system numerology; and obtain the reference signal from the identified set of resource elements. Numerous other aspects are provided.

A synchronization method, an apparatus, and a system, which relate to the communications field and applied to synchronization signal transmission to implement synchronization of data frame transmission between devices on an unlicensed carrier are provided. The synchronization method is applied to synchronization on an unlicensed carrier. A network device sets a synchronization signal in a first subframe, and the network device sends the first subframe or the first subframe and a second subframe to user equipment, where the first subframe includes M orthogonal frequency division multiplexing (OFDM) symbols, the second subframe includes N OFDM symbols, M and N are positive integers, M>N, and the first subframe and the second subframe are subframes of an unlicensed carrier.

Methods and apparatus for frequency offset estimation are disclosed. In an exemplary embodiment, a method includes determining a demodulation reference signal (DMRS) frequency offset estimate from DMRS symbols in a received signal, and determining a cyclic prefix (CP) frequency offset estimate from cyclic prefix values in the received signal. The method also includes combining the DMRS and CP frequency offset estimates to determine a final frequency offset estimate. In an exemplary embodiment, an apparatus includes a DMRS frequency offset estimator that determines a DMRS frequency offset estimate based on DMRS symbols received in an uplink transmission, and a cyclic prefix (CP) frequency offset estimator that determines a CP frequency offset estimate based on cyclic prefix values in the uplink transmission. The apparatus also includes an offset combiner that combines the DMRS frequency offset estimate with the CP frequency offset estimate to generate a final frequency offset estimate.

A method for transmitting information in a communication system, a base station and a user equipment. The method includes mapping a synchronous signal and a broadcast channel to be transmitted to preset one or more time-frequency resource blocks in a target carrier, where a numerology used by the target carrier is a first numerology group, and the first numerology group includes any one or more numerologies that are allowed to be used by the target carrier; the one or more time-frequency resource blocks are located within an initial access subband of the target carrier and uses a second numerology, where the second numerology is a fixed numerology; the broadcast channel carries at least configuration information of the initial access subband; and the initial access subband is a subband corresponding to a numerology in the first numerology group; and transmitting the one or more time-frequency resource blocks to a user equipment.

A intelligent backhaul radio is disclosed that is compact, light and low power for street level mounting, operates at 100 Mb/s or higher at ranges of 300 m or longer in obstructed LOS conditions with low latencies of 5 ms or less, can support PTP and PMP topologies, uses radio spectrum resources efficiently and does not require precise physical antenna alignment.