31 results about "Asynchronous channels" patented technology

A communication system communicates control data in unused segments in the data stream of an asynchronous channel. The communication system includes a transmitting unit and a receiving unit. The transmitting unit transmits communications data to the receiving unit via the asynchronous channel, in compliance with the channel's asynchronous protocol. However, the transmitting unit transmits control data to the receiving unit in unused segments of the data stream.

An apparatus and method for an improved asynchronous communication channel between a transmitter and a receiver having separate clocks. The invention provides a simple implementation that solves both the overflow and the underflow problem using the same mechanism, and reduces complexity by elimination of the control split between the two clock domains. A first embodiment of the invention is a method for preventing packet underflow and packet overflow for packets sent across an asynchronous link between a transmitter and a receiver, including a buffer that can store a number of packets greater than an ideal number of packets. The method includes sending a predetermined number of drop-me warning packets and sending one or more drop-me packets from the transmitter to the receiver, receiving the predetermined number of drop-me warning packets and the one or more drop-me packets in the buffer, compensating for packet overflow when the number of packets is greater than the ideal number of packets in the buffer by skipping at least one drop-me packet, and compensating for packet underflow in the buffer when the number of packets is less than the ideal number of packets by stalling access to the buffer for one or more clock cycles. A second embodiment of the invention is an asynchronous link for packets sent between a transmitter having a first clock and a receiver having a second clock, including a buffer to receive the first clock from the transmitter and receive from the transmitter a number of packets equal to or different to a predetermined ideal number of packets, a write pointer, and a read pointer, and a read pointer control circuit to change the read pointer, wherein the buffer can receive drop-me packets, and the read pointer can skip a drop-me packet in the buffer.

The invention discloses a cooperative MAC protocol implementation method on the basis of multiple asynchronous channels in vehicular vdhoc networks, and belongs to the technical field of vehicle-mounted wireless communication. The cooperative MAC protocol implementation method on the basis of the multiple asynchronous channels in the vehicular vdhoc networks comprises a method for selecting cooperative relay nodes, a multi-channel selection and coordination strategy and a retransmission mechanism of emergency messages and handshake messages. According to the cooperative MAC protocol implementation method on the basis of the multiple asynchronous channels in the vehicular vdhoc networks, mutual cooperation between the nodes is carried out, channel state information and other node state information can be obtained, and the problem that hidden terminals of the multiple channels exist in the transmission process is well solved; due to the retransmission mechanism of the cooperative relay nodes, nodes working in other service channels can also receive lost information of a control channel, reliable transmission of data in the highly-mobile environment is achieved, and communication reliability and the network throughput are improved.

The invention provides a method for correcting asynchronous sampling time sequences between channels, which comprises the following steps of: S1, setting a radio frequency signal with a specified frequency, outputting M radio frequency signals and converting the M radio frequency signals into intermediate frequency signals; S2, acquiring and storing the M intermediate frequency signals through an AD sampling unit, repeating the S1 to S2 to sample and store the AD data of the intermediate frequency signals of multiple frequencies; S3, calculating the phase difference between the collected and stored AD data of other channels and that in the reference channel under all frequencies, drawing a phase difference curve that the phase difference changes along with the frequency, and drawing a real phase difference change trend curve at the same time; S4, determining channels with asynchronous sampling according to the phase difference curve, and performing corresponding correction on the asynchronous channels; and S5, verifying the corrected channels. The invention aims to quickly correct the delay inequality of asynchronous sampling time sequences of cross-signal periods among multiple channels without introducing calculation errors, hardware required by a correction system is simple, the synchronous debugging efficiency is greatly improved, and the universality range of the correction method is expanded.

This application discloses circuits and apparatus configured to measure performance of asynchronous circuits by injecting data in to inputs of asynchronous circuits and consuming data from the outputs without interfering in the functionality of the asynchronous circuits. This application also discloses systems and methods for assessing the performance of asynchronous channels and / or IP blocks by providing an unambiguous performance value which can be used for performance analysis and comparison.