摘要:
Provided is a burst mode optical receiver considering a characteristic of an extinction ratio of a received optical signal is provided. By using a peak detector considering a characteristic of an extinction ratio, top and bottom peak voltages of actual burst packets can be precisely detected while not being affected by a DC offset corresponding to an extinction ratio even though burst packets having a DC offset corresponding to the extinction ratio are received. Accordingly, waveform distortion of a signal output from the burst mode optical receiver can be minimized.
摘要:
Provided is a burst mode optical receiver capable of accurately detecting an optical signal of minimum amplitude, by automatically controlling a gain of a pre-amplifier according to an amplitude of an input optical signal. The burst mode optical receiver can automatically control a gain of a pre-amplifier according to the amplitude of an input optical signal using an output signal of a first peak detector. In other words, when the input optical signal has a small amplitude that meets the receiving sensitivity of the burst mode optical receiver, the gain of the pre-amplifier automatically increases, thereby improving the receiving sensitivity of the burst mode optical receiver.
摘要:
In a wireless multi-hop network, a transmission scheduling apparatus calculates a transmission demand of every node within the wireless multi-hop network, and allocates a time slot to each node by using the transmission demand of each node.
摘要:
In order for a source node including a vehicle multihop protocol unicast apparatus to route data to a destination node, the source node broadcasts a location request message to neighbor node and receives a location response message from the neighbor nodes in response to the location request message. Therefore, the source node routs unicast data on the basis of the location information of the destination node included in the location response message. At this time, the source node uses a location based forwarder selecting algorithm in order to select a forwarder.
摘要:
An apparatus for time synchronization of an orthogonal frequency division multiplexing (OFDM) system oversamples a received signal using a master clock having a frequency at least four times higher than a minimum sampling frequency in a transmission apparatus, sets one of a plurality of oversampled signals to an on-time signal, and shifts each of the remaining oversampled signals by a predetermined time on the basis of the on-time signal. The apparatus for time synchronization calculates a correlation value by correlating each of the shifted signals and the on-time signal with a previously known signal, detects a maximum energy value among the calculated correlation values, and detects a start point of a frame by comparing the maximum energy value with a predetermined threshold value.
摘要:
In a vehicle communication system, a multi channel operation apparatus for communication of a vehicle or a road side base station operates a multi channel in one physical layer and differentially transmits a frame through a corresponding channel according to a user priority order value of a frame to transmit.
摘要:
In order for a source node including a vehicle multihop protocol unicast apparatus to route data to a destination node, the source node broadcasts a location request message to neighbor node and receives a location response message from the neighbor nodes in response to the location request message. Therefore, the source node routes unicast data on the basis of the location information of the destination node included in the location response message. At this time, the source node uses a location based forwarder selecting algorithm in order to select a forwarder.
摘要:
A first roadside equipment operates as a transmitting/receiving mode in a control channel interval of an Nth synchronization interval so as to support a handover. In this instance, a second roadside equipment neighboring to the first roadside equipment operates as a receiving mode in the control channel interval of the Nth synchronization interval. The first roadside equipment operates as the receiving mode in a control channel interval of an (N+1)th synchronization interval. In this instance, the second roadside equipment operates as the transmitting/receiving mode in the control channel interval of the (N+1)th synchronization interval.
摘要:
An apparatus for time synchronization of an orthogonal frequency division multiplexing (OFDM) system oversamples a received signal using a master clock having a frequency at least four times higher than a minimum sampling frequency in a transmission apparatus, sets one of a plurality of oversampled signals to an on-time signal, and shifts each of the remaining oversampled signals by a predetermined time on the basis of the on-time signal. The apparatus for time synchronization calculates a correlation value by correlating each of the shifted signals and the on-time signal with a previously known signal, detects a maximum energy value among the calculated correlation values, and detects a start point of a frame by comparing the maximum energy value with a predetermined threshold value.
摘要:
In a vehicle communication system, a frame transmitting apparatus gives a transmission opportunity to an emergency frame received from an upper layer without EDCA (Enhanced Distributed Channel Access), and gives a transmission opportunity to a generic frame received from an upper layer through EDCA.