We disclose an optical add-drop multiplexer that can apply different routing operations to different subcarriers of a data frame. In an example embodiment, the digital signal processor (DSP) of the optical add-drop multiplexer carries out subcarrier-specific add, drop, and pass-through operations in the electrical frequency domain, which enables the DSP to only partially unwrap the pass-through subcarriers, thereby at least partially avoiding some of the more processing-power-hungry DSP operations and reducing the sub-wavelength routing latency accordingly. Also disclosed is an example data-frame structure that can be used to provide subcarrier-specific routing instructions to the optical add-drop multiplexer.

A symbol boundary detection method includes: calculating desired signal power according to a receiving signal by a receiver device; calculating interference power according to the receiving signal by the receiver device; calculating a signal-to-interference power ratio according to the desired signal power and the interference power by the receiver device; finding a best signal-to-interference power ratio to determine a reference symbol boundary time by the receiver device; and processing the receiving signal according to the reference symbol boundary time by the receiver device for a subsequent demodulation process performed by a demodulator circuit.

The present disclosure discloses a method for adjusting one or more LO frequencies in a receiver. The receiver performs down conversion on a received signal through one or more mixers by using the one or more LO frequencies, and outputs one or more symbols through an ADC. The method comprising the steps of: for each of the one or more LO frequencies, estimating a new LO frequency corresponding to a best signal quality of the received signal; and adjusting the LO frequency into the new LO frequency. The present disclosure also relates to a receiver for adjusting one or more LO frequencies.

A transmitting apparatus is provided. The transmitting apparatus includes: a frame generator configured to generate a frame including a plurality of orthogonal frequency-division multiplexing (OFDM) symbols; and a guard interval (GI) inserter configured to insert GIs into the generated frame, wherein the plurality of OFDM symbols are divided into a bootstrap, a preamble, and a payload, and the GI inserter inserts first GIs having a size corresponding to a fast Fourier transform (FFT) size of each of OFDM symbols configuring the payload into front ends of each of the OFDM symbols, inserts second GIs having a size corresponding to a quotient obtained by dividing an extra region of the payload calculated based on the FFT size of the OFDM symbols configuring the payload, the number of OFDM symbols, and the size of the first GIs by the number of OFDM symbols into front ends of each of the first GIs, and inserts a cyclic postfix (CP) having a size corresponding to the remainder remaining after dividing the extra region of the payload by the number of OFDM symbols into a rear end of a final OFDM symbol configuring the payload.

A leakage detection instrument may receive an electromagnetic signal radiated from a leakage location within a cable network system. The instrument may determine the leak based on spectral analysis and without the use of tagged or test signals.

A chirp spread spectrum (CSS) receiver may reject, based on a data alignment chirp that includes an identifier that is a mismatch to a preconfigured identifier, a message early and before fully receiving/decoding the message. A receiver may receive a sequence of training chirps for symbol alignment followed by a single opposite chirp for data alignment. Training chirps may be processed through a fast-Fourier transform (FFT) and the resulting values accumulated. The receiver may align, based on the received chirps of the preamble and the accumulated values exceeding the threshold, its symbol reception. Using this symbol alignment, the receiver may await a single opposite chirp after the sequence of training chirps. The single opposite chirp may indicate data alignment and comprise an encoded identifier. The receiver may reject the message and terminate further message processing based on the encoded identifier being a mismatch to a preconfigured identifier.

Data acquisition in a chirp spread spectrum (CSS) signal may use a data alignment indicator of a single down chirp signal or single upchirp signal. A receiver may receive part or all of a preamble comprising a sequence of training chirps for symbol alignment followed by a single opposite chirp for data alignment. Training chirps may be processed through a fast-Fourier transform (FFT), and the values from the FFT may be accumulated. The accumulated values may exceed a threshold for detection. The receiver may align, based on the received chirps of the preamble and exceeding the threshold, its symbol reception. Using this symbol alignment, the receiver may await a single opposite chirp after the sequence of training chirps. The single opposite chirp may indicate data alignment. Upon receipt of the opposite chirp, the receiver may start data acquisition based on chirps following the single opposite chirp.

This application discloses a data sending method, a data receiving method, and an apparatus. The data sending method includes: if first type data is punctured, preserving, by a network device, a punctured first data subset in the first type data and puncture location information of the first data subset in the first type data, and retransmitting the first data subset within a second scheduling period to a user equipment. In this way, the network device does not need to wait for feedback from the user equipment before the network device can perform a retransmission operation, so that latency of retransmission is reduced. In addition, the network device only needs to retransmit the punctured first data subset within the second scheduling period but does not need to retransmit the entire first type data, so that an amount of data to be retransmitted is reduced and fewer transmission resources are consumed.

The present invention provides a data transmission method and a communications device. The communications device includes: a transceiver, configured to send a transmission frame to a second communications device, so that the second communications device acquires data information in the transmission frame, where the transmission frame includes a first part and a second part, the transceiver sends the first part of the transmission frame by using a first quantity of subcarriers, the transceiver sends the second part of the transmission frame by using a second quantity of subcarriers, and the first quantity is not equal to the second quantity; and the transceiver, further configured to perform a next time of information transmission with the second communications device. A throughput can be effectively increased.

In one aspect, an apparatus includes: a fast Fourier transform (FFT) engine to receive orthogonal frequency division multiplexing (OFDM) samples of one or more OFDM symbols and convert the one or more OFDM samples into a plurality of frequency domain carriers; and a tone cancellation circuit coupled to the FFT engine to receive the one or more OFDM samples and generate a plurality of frequency carriers for the one or more OFDM samples, identify a highest magnitude frequency carrier of the plurality of frequency carriers, and remove tone interference from the OFDM samples based at least in part on the highest magnitude frequency carrier.