The Simulation And Performance Analysis Of Train Communication Network Based On LAN

Train Communication Network (TC.N) is a data communi cat ion network in which all control, detection and diagnosis information are carried for interconnecting programmable equipments between and within rail vehicles. The International Electrotechnical Commission (TEC) has constituted a TON standard ?DEC 61375-1. However, no train network products with independent knowledge property have been developed but few technologies relevant to TON been introduced in our country. On the other hand, products supporting IEC 61375-1 are limited with high price. Deep research on TCN technology is made in this paper considering above cases.Two notable characteristics of TCN are as follows: (1) Polling MAC strategy is adopted in link layer by IEC 61375-1 to ensure the certainty of data transmission time; (2) Train inauguration procedure is devised to realize the automatic allocation of rail vehicle address in the network.The paper consists of two nain parts: 1. A sinulating system ofWire Twisted Bus (WTB) inauguration. The system was completed usingWindows Socket programming technology based on Windows98 andC++Builder 5.0 station under the environment of our laboratory LAN(100M bus topology). The naming of vehicle nodes during inaugurationis emphasized. It is also indicated that the system may simulatefunctions prescribed in IEC 61375-1 by running the program. 2. Theanalysis and comparison between Multifunction Vehicle Bus (MVB)polling MAC mode and CSMA/CD MAC mode under normalizing condition.Normalization processing was made for contrast in that data rateregulated in IEC 61375-1 is 1 Mbps, while the data rate of generalEthernet is very high. Thus the normalizing rate is 1 Mbps. Theperformances such as throughput and time delay, etc. with respect toMVB and CSMA/CD under the same condition were analyzed. Moreover thecurves according to computing results were plotted by Matlab. Analysisresults show that MVB predominates at aspects of throughput and delay. Two pieces of reason which cause this result are: (1) IEEE 802. 3 standard adopted in Ethernet designates 368 bits minimum data field size in MAC fraae, filling bits will be loaded if data length is shorter than 368 bits, which causes extra spending. On the contrary, the naxiauB process data length in IEC 61375-1 is only 256 bits. (2) Actual Ethernet rate may be lOMbps, lOOMbps, lOOOMbps, which is far higher than 1VL Consequently it is likely that CSMA/CD fulfill functions of MVB polling strategy.