A method for transmitting a signal is described, wherein the method has transforming a signal into a frequency domain to obtain a spectrum, forming a filtered spectrum according to a filter spectrum and occupying a set of subcarriers of a frequency domain representation of an Orthogonal Frequency Division Multiplex (OFDM) signal with the filtered spectrum. A temporary signal is obtained by transforming the frequency domain representation of the OFDM signal into a time domain. The temporary signal is subjected to a phase modulation.

In a method for generating a data unit, it is determined whether the data unit is to be transmitted using single carrier (SC) modulation or orthogonal frequency division (OFDM) modulation. When it is determined that the data unit is to be transmitted using SC modulation, a header field of the data unit is generated using a first technique to indicate that the data unit conforms to a first protocol and/or whether the data unit conforms to a first PHY mode or a second PHY mode of the first protocol. When it is determined that the data unit is to be transmitted using OFDM modulation, the header field is generated using a second technique to indicate that the data unit conforms to the first protocol and/or whether the data unit conforms to the first PHY mode or the second PHY mode of the first protocol.

The present invention relates to the mobile communications field, and in particular, to a synchronization signal sending method. A network device obtains a first signal after performing discrete Fourier transform DFT and orthogonal frequency division multiplexing OFDM modulation, or OFDM modulation on a ZC sequence whose root index is 1; the network device obtains a second signal after performing DFT and OFDM modulation, or OFDM modulation on a conjugate sequence of the ZC sequence whose root index is 1; the network device generates a synchronization signal, where the synchronization signal includes the first signal and the second signal; and the network device sends the synchronization signal to a terminal device. By using this method, when there is a relatively large frequency offset between the terminal device and the network device, an M2M service requirement can still be met.

A wireless device transmits, during a first period, a first plurality of voice packets of a first talking period on a first plurality of subcarriers of a first carrier. The wireless device transmits, during a second period, a second plurality of voice packets of a second talking period on a second plurality of subcarriers of a second carrier. The wireless device transmits, in the first period and the second period, data traffic packets on a third plurality of subcarriers. There is at least one guard band between at least two subcarriers in the third plurality of subcarriers.

A method for mapping, by a base station, a channel state information reference signal (CSI RS) in a wireless communication system, the method comprising: generating the CSI for eight antenna ports; selecting a resource element (RE) set from a plurality of RE sets in a subframe using an extended cyclic prefix (CP), wherein the selected RE set includes four pairs of REs in consecutive orthogonal frequency division multiplexing (OFDM) symbols, and wherein the four pairs of REs are separated from each other by constant subcarrier spacing in the consecutive OFDM symbols; and mapping the CSI RS for the eight antenna ports to the selected RE set.

A communication device for reducing complexity of preamble detection comprises a storage device for storing instructions and a processing circuit coupled to the storage device. The processing circuit is configured to execute the instructions stored in the storage device. The instructions comprise being configured with a plurality of preambles; transmitting a first preamble of the plurality of preambles; and transmitting a second preamble of the plurality of preambles, wherein the first preamble is associated with the second preamble according to an association.

An optical transmitter transmits an orthogonal frequency division multiplexing symbol in which only one-half of available subcarriers are modulated with data and the remaining subcarriers are suppressed by not modulating with data. The transmission is of duration equal to half the symbol period of the OFDM symbol, resulting in a half-cycle transmission. An optical receiver receives the half-cycle transmission OFDM symbol, regenerates the full time domain representation and recovers data modulated on the one-half of available subcarriers. The modulated subcarriers and the suppressed subcarriers alternate in the frequency domain.

Methods, systems, and devices for wireless communication are described that provide for generating a multicarrier wakeup signal that is modulated using multiple on-off keying (OOK) patterns. In some cases, the OOK pattern may be constructed using one or more of the following techniques: forward error correction (FEC) coding, spreading, encoding (e.g., DC balance encoding such as Manchester encoding), and orthogonal frequency division multiplexing (OFDM) overlay mapping. The resulting signal may serve to increase the sensitivity of the receiver. The OOK patterns may include on portions and off portions that are indicative of different bit values, such as a one bit or a zero bit. The multicarrier wakeup signal may be decoded by a first radio of a wireless device that compares the energy of the signal over different time periods to determine the bit value. Once determined, the wireless device may choose to activate a second radio for communication.

Disclosed is a synchronization signal receiving method comprising a step of respectively receiving, from a plurality of base stations, a plurality of synchronization signals generated by using a predetermined repetition frequency, sequence, and phase pattern vector, measuring a start timing of a frame, a sequence index, and an index of the phase pattern vector by using the plurality of synchronization signals with respect to each of the plurality of base stations, selecting the base station having the highest correlation value calculated as a result of the measurement among the plurality of base stations, and establishing a connection with the selected base station, wherein the phase pattern vector repeatedly changes the phase of the sequence at the repetition frequency.

A communication circuit supports a first communication protocol and a second communication protocol that is different from the first communication protocol. A number of signals include first signals conveying first information messages and second signals conveying second information messages. The first information messages include a repetitive message having fixed repeated content and the second information messages include a non-repetitive message having variable content. The first signals and the second signals are transmitted via the communication circuit using the first communication protocol for the first signals and the second communication protocol for the second signals.