Patent ID: 8488617
Filing Date: 2013-07-16
Classification: H04L

Abstract:
1. A railway-train communication apparatus that performs transmission processes of transmitting a first type of transmission signal flowing through an inter-car network constructed between cars of a railway train and a second type of transmission signal flowing through an in-car network constructed in each of the cars, the railway-train communication apparatus comprising: a node device that is provided in each of the cars, the node device including: the first controller that is connected to the layer 2 switch and controls signal transmission between the inter-car network and the in-car network, wherein the first signal converter converts the first type of transmission signal received from an adjacent inter-car network on a first side into the second type of transmission signal and outputs the second type of transmission signal to the layer 2 switch, and converts the second type of transmission signal received from the layer 2 switch into the first type of transmission signal and outputs the first type of transmission signal to the adjacent inter-car network on the first side, and the second signal converter converts the first type of transmission signal received from an adjacent inter-car network on a second side into the second type of transmission signal and outputs the second type of transmission signal to the layer 2 switch, and converts the second type of transmission signal received from the layer 2 switch into the first type of transmission signal and outputs the first type of transmission signal to the adjacent inter-car network on the second side, and wherein each of the first signal converter and the second signal converter includes at least two types of buffer memories for compensating a difference in transmission speed between the first type of transmission signal and the second type of transmission signal, the buffer memories are provided in a stage before a converting unit that converts the second type of transmission signal to the first type of transmission signal, one of the buffer memories is a buffer memory in which high-priority data is accumulated, and the other of the buffer memories is a buffer memory in which low-priority data is accumulated, and a determining unit that determines a highness and lowness of priority and outputs data to the at least two types of buffer memories based on the priority.