Abstract:
This disclosure describes systems, methods, and devices related to signal detection. A device is configured to: determine a physical layer protocol data unit (PPDU); append a common preamble to the PPDU, wherein the preamble comprises a common short training field and a common preamble length field; generate a frame comprising the preamble and the PPDU; and send the frame.
Abstract:
Disclosed herein is a system combining OFDM standard modulation with a superimposition of Orbital Angular Momentum modes, each OAM modes consisting in an overlapping decimated IFFTs with the main mode standard OFDM signal. Orthogonality of the OAM modes is assessed. A frame structure embodying both main mode OFDM samples and overlapping OAM modes is proposed.
Abstract:
Disclosed herein is a radio communications method that comprises carrying out, by a transmitter (7), the following steps: providing a digital time signal carrying digital symbols to be transmitted; and transmitting a radio frequency signal carrying said digital time signal. The method further comprises carrying out, by a receiver (8), the following steps: receiving the radio frequency signal transmitted by the transmitter (7); processing the received radio frequency signal so as to obtain a corresponding incoming digital signal; and extracting, from the incoming digital signal, the digital symbols carried by said incoming digital signal. Said digital time signal carrying the digital symbols to be transmitted results from an approximation of the Hilbert transform in frequency domain, which approximation is based on a frequency main mode and one or more frequency twisted modes, wherein said frequency main and twisted modes carry, each, respective digital symbols to be transmitted. The transmitted signal is produced by a bank of IFFT each devoted to one mode and consists in overlapped OFDM modes with growing bandwidths per modes.
Abstract:
A transmitting apparatus is disclosed. The transmitting apparatus includes a preamble symbol inserter configured to insert to a frame a preamble symbol including a signaling information, a guard interval inserter configured to insert guard intervals to both ends of the preamble symbol, and a transmitter configured to transmit a frame including the preamble symbol and the guard intervals, wherein one of the guard intervals which are inserted to both ends of the preamble symbol comprises a pseudo random noise (PN) sequence and another guard interval includes one between the PN sequence and a part of the signaling information. Accordingly, no separate algorithm to estimate size of FFT of the preamble symbol and the guard interval is necessary, robust signal detection and synchronization is enabled by the PN sequence inserted to the guard interval, and compensation of interference which is generated under multipath channel environment deems to be easier.
Abstract:
A transmitting end of an OFDM wireless communication system may generate a training sequence and attach the training sequence to a data sequence that contains information data. A receiving end of the OFDM wireless communication system may identify a starting position of the data sequence and further extract the data sequence.
Abstract:
A transmitter transmits payload data using Orthogonal Frequency Division Multiplexed (OFDM) symbols. The transmitter comprises a frame builder configured to receive the payload data to be transmitted and to receive first signalling data for use in detecting and recovering the payload data at a receiver, and to form the payload data and the first signalling data into frames for transmission, the first signalling data forming a part of the frames with the payload data. A modulator is configured to modulate a first OFDM symbol with the first signalling data and to modulate one or more second OFDM symbols with the payload data. A signature sequence processor provides a signature sequence, a combiner combines the signature sequence with the first OFDM symbol, and a transmission unit transmits the first and second OFDM symbols. The signature sequence provided by the signature sequence processor comprises at least one of a first synchronisation sequence or a second message sequence, the first synchronisation sequence and/or the second message sequence being combined by the combiner with the first OFMD symbol. The first synclironisation sequence is provided for a receiver to detect and to recover the first signalling data from the first OFDM symbol and the second message sequence provides message information to the receiver. The message information may be used to convey a specific message to a user such as an emergency warning relating to a natural disaster such as an earthquake or a tsunami warning.
Abstract:
The present disclosure describes systems and methods for identifying a signal that is a product of two or more other signals, ie intermodulation distortion. In an embodiment, the presence of a particular signal is determined and identified by applying a cyclostationarity detection technique, such as comparing a cyclic autocorrelation function of a product signal with the cyclic autocorrelation function of at least one of the signals which formed the product signal.
Abstract:
The present invention relates to a method and apparatus for estimating the signal to noise ratio of a broadcast OFDM signal. The invention compares signals of the data in a guard interval and the corresponding part of the data frame of an OFDM symbol. A sum and difference operation is then performed on the data in the compared signals to enable a Signal to Noise Ratio to be calculated.
Abstract:
A method for detecting the digital quality of a radio signal includes: receiving a radio signal including a digital portion modulated by a series of symbols each including a plurality of samples; computing correlation points between endpoint samples in cyclic prefix regions of adjacent symbols; and using the correlation points to produce a digital signal quality metric. Receivers that implement the method are also provided.