A method and system for multipulse-pulse position modulation optical transmission that includes selecting a multipulse-pulse position modulation having a symbol alphabet having an upper-bound symbol alphabet size, and determining, based on at least one transmission characteristic associated with a transmitter, a subset of symbols of the selected symbol alphabet capable of being transmitted by the transmitter, the subset of symbols having a set of binary codewords. The method and system may include identifying two-symbol concatenation of binary codewords in the set of binary codewords, calculating a cross correlation of binary codeword in the set of binary code words through every two-symbol concatenation, determining a set of one or more acceptable codeword combinations by eliminating a portion of two-symbol concatenation of codewords corresponding to overlapping peaks in the respective calculated cross correlations, and transmitting, by the transmitter via an optical communication channel, information encoded based on the determined acceptable codeword combinations.

A method for synchronizing a data frame and data symbols in a communication system includes generating a training sequence including a serial sequence of data symbols that are conjugate symmetric, inserting the training sequence in a transmitter-side data frame, converting constituent data symbols of the transmitter-side data frame to communication signals, transmitting the communication signals from a transmitter to a receiver, converting the communication signals to a stream of received data symbols, detecting presence of the training sequence in the stream of received data symbols, and identifying a position of a received data frame from the presence of the training sequence.

Disclosed is receiver apparatus including a first input configured to receive a first signal, a second input configured to receive a second signal, a switching circuit configured to alternate between the first and second signal from the first and second inputs, a receiver configured to sample the input signal to produce a plurality of input samples, a reference sequence generator configured to generate a reference signal, and a correlator configured to correlate the first and second signals with the reference signal to detect a correlation event, the correlator including a first buffer configured to receive signals from the first input and a second buffer configured to receive signals from the second input, wherein the correlator is configured to process the first signal in the first buffer, while the second buffer receives the second signal.

A method for receiving and transmitting synchronization signal is provided. The method is applicable to a wireless communication device. The wireless communication device has a local timing. The method includes the following steps. Receive at least one synchronization signal. If a signal power of at least one of the at least one synchronization signal is greater than or equal to a signal power threshold, select one of the at least one synchronization signal as a reference synchronization signal according to a priority rule, and synchronize the local timing to the reference synchronization signal. If the signal power of each the synchronization signal is less than the signal power threshold, send a local synchronization signal according to the local timing. If the reference synchronization signal meets a forwarding criterion, forward the reference synchronization signal, wherein the forwarding criterion includes a power constraint and a hop count constraint.

A handshaking process for time-reversal wireless communication is provided. A first device receives a handshake signal transmitted from a second device through multiple propagation paths, the handshake signal including a preamble and a training sequence, in which the training sequence includes a sequence of symbols known to the first and second devices. A synchronization index is determined based on the preamble, and the training sequence in the handshake signal is identified based on the synchronization index. A channel response signal is determined based on the received training sequence, and a signature waveform that is a time-reversed signal of the channel response signal is generated. A transmission signal is generated based on transmit data and the signature waveform, in which the transmit data are data configured to be transmitted to the second device.

A method and apparatus for identifying a search window of carrier-frequency-offset-corrected samples in which a first intermediate signal from a demodulator does not exceed a predetermined threshold, convolving a second intermediate signal from the demodulator within the search window with a predefined pattern to provide a convolution result, determining if an absolute peak of the convolution result exceeds a preamble pattern confirmation threshold, in response to the absolute peak of the convolution result exceeding the preamble confirmation threshold, confirming a preamble pattern detection event to provide a confirmed preamble pattern detection event of a confirmed preamble pattern, and receiving a signal including the confirmed preamble pattern to provide a received digital signal extracted from the signal.

A method may comprise receiving and sampling a signal. The signal may encode a data packet. A slice may be generated and stored comprising a pair of values for each of a selected number of samples of the signal representing a correlation of the signal to reference functions in the receiver. The presence of the data packet may then be detected and the detected packet decoded from the stored slices. The generating and storing slices may be carried out as the received signal is sampled. The sampled values of the signal may be discarded as the slices are generated and stored. The slice representation of the signal can be manipulated to generate filters with flexible bandwidth and center frequency.

A communication method is to be performed by a secondary transceiver. The secondary transceiver is operatively associated with a primary transceiver. The primary transceiver is configured to transmit an orthogonal frequency division multiplexing (OFDM) signal that has consecutive OFDM symbols. The OFDM symbol has a fixed OFDM symbol length and includes a cyclic prefix that has a fixed prefix length. The communication method includes steps of: A) upon receipt of the OFDM signal, determining a starting position of the cyclic prefix; and B) transmitting a to-be-transmitted signal during a time corresponding to the cyclic prefix of the one of the OFDM symbols or another one of the OFDM symbols subsequent to the one of the OFDM symbols.

Communication systems and methods in accordance with various embodiments of the invention utilize modulation on zeros. Carrier frequency offsets (CFO) can result in an unknown rotation of all zeros of a received signal's z-transform. Therefore, a binary MOCZ scheme (BMOCZ) can be utilized in which the modulated binary data is encoded using a cycling register code (e.g. CPC or ACPC), enabling receivers to determine cyclic shifts in the BMOCZ symbol resulting from a CFO. Receivers in accordance with several embodiments of the invention include decoders capable of decoding information bits from received discrete-time baseband signals by: estimating a timing offset for the received signal; determining a plurality of zeros of a z-transform of the received symbol; identifying zeros from the plurality of zeros that encode received bits by correcting fractional rotations resulting from the CFO; and decoding information bits based upon the received bits using a cycling register code.

Systems and methods for detecting a synchronization code word embedded in a plurality of frames of a signal are described. In one example embodiment, the synchronization code word contains “s” bits, embedded one bit per frame in “s” frames of an input signal. The method of detecting this synchronization code word includes: initiating a first segmentation procedure wherein “n” segments are defined in each signal frame of the input signal. A first correlation threshold value, which is based on the synchronization code word, is used to identify in the “n” segments, a first segment having the highest likelihood of containing at least a portion of the synchronization code word. The first segment is used to initiate a recursive detection procedure incorporating one or more additional segmentation procedures and one or more additional correlation threshold values, to detect the synchronization code word in a sub-divided portion of the first segment.