Itran Communications Ltd.

Yitran Communications Ltd.

Oren Kaufman

Dan Raphaeli

Boris Zarud

Evgeny Bassin

Gregory Lerner

Mordechai Mushkin

Tanya Rosing

A novel and useful acquisition and synchronization mechanism for spread spectrum communication systems whereby a synchronization sequence comprising a plurality of known symbols spaced apart by predefined time delay intervals is transmitted as the start of packet signal. At the transmitter, a synchronization sequence is transmitted at the beginning of each packet. A synchronization sequence is generated which includes a plurality of symbols with predefined time gaps between each of the symbols. Multiple synchronization sequences may be generated wherein each sequence comprises a unique set of time delays or gaps between each of the symbols. Each set of unique time delays or gaps between symbols of a sequence is stored as a synchronization sequence gap template in memory. When required to generate a synchronization sequence, the sequence generator outputs the plurality of synchronization symbols and inserts a specific time delay between each of the symbols in accordance with the contents of the gap template for the particular synchronization sequence.

Method and apparatus for generating a synchronization sequence in a spread spectrum communications transceiver

A novel and useful mechanism for detecting intrusion and jamming attempts by an imposter node. A time window defined as an emergency window is reserved after the end of a packet and before an acknowledgement window. Nodes that detect the presence of an intruder transmit an emergency packet during the emergency time window to inform the receive node that the packet it received was sent from an imposter node. Attempts to jam the transmission of the emergency packet from the victim node to the receive node are detected by listening during the emergency window time period for carrier signal that indicates that an emergency packet is trying to be sent. An emergency packet request message is sent by the receive node in response which causes the victim node to resend the emergency packet.

Mechanism for detecting intrusion and jamming attempts in a shared media based communications network

A novel robust communications scheme whereby a repetition code at the transmitter and an associated cumulative decoder at the receiver are used to increase the reliability of transmission in a communications system. The robust communications scheme of the present invention is effective to increase the reliability of transmission by repetitively transmitting each data segment a number of times in accordance with a repetition code and subsequently collecting the received energy at the receiver over an accordingly longer period of time. Accumulating the received energy over a longer period of time at the receiver, yields a marked improvement in the signal to noise ratio (SNR) of the receiver.

Robust communications system utilizing repetition code and cumulative decoder associated therewith

A novel and useful acquisition and synchronization mechanism for spread spectrum communication systems whereby a synchronization sequence comprising a plurality of known symbols spaced apart by predefined time delay intervals is transmitted as the start of packet signal. At the receiver, the received signal is correlated against the synchronization sequence using the predefined gaps or time delay intervals inserted between the symbols. The received signal is linearly correlated to generate a correlation peak for each symbol received. The expected position of each correlation peak is calculated and compared to the positions of the correlation peaks received. If the number of matches exceeds a threshold, synchronization is declared.

Acquisition of sychronization in a spread spectrum communications transceiver

A interleaver/de-interleaver mechanism for reducing the latency of transmitted interleaved codewords. The interleaver/de-interleaver mechanism utilizes a shortened first codeword which functions to offset the interleaving and transmission on subsequent codewords so as to achieve reduced latency depending on the degree of shortening applied. The interleaver/de-interleaver mechanism is particularly useful in power line carrier based systems to reduce the exposure to burst errors by providing interleaving with minimal latency penalty.

Reduced latency interleaver utilizing shortened first codeword

A novel and useful windowing mechanism for reducing the out of band harmonics of an output transmit signal. The windowing mechanism functions to smooth the transition between two consecutive transmit waveforms. The mechanism of present invention is particularly useful in communication systems characterized by consecutively transmitted symbols whereby the concatenation of transmitted waveforms causes discontinuities between symbols. The windowing mechanism is operative to reduce the effect of these discontinuities to reduce out of band harmonics of the transmitted output signal. The windowing mechanism extends each transmit waveform both earlier and later in time thus creating extending waveform portions on either end of the transmit waveform. The extended portions are then multiplied by a suitable windowing function and the result is summed with the next transmit waveform.

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Beer Sheva, Israel

Oren Kaufman