Study On ATM Technology And The Inverse Multiplexing Technology (IMA)

It combines all the excellences of occupying band statistically by Group Switch, flexible and small time delay by Circuit Switch, and it tries hard to use a unique and general switch structure to deal with all kinds of business and multi-media application. This mode improves the network transfer rate and utilizes network resource fully, and it allows customers to choose the service quality. In virtue of the characteristics of flexible bandwidth assignment, perfect service quality control, low time delay and high safety, ATM has broad application in the wide area network. At present, the communication networks and communication equipments based on ATM technology are very mature. ATM technology accounts for a substantial portion in the internal and international communication field. The transmission rate can reach to tens of mega bits even hundreds of mega bits mainly depends on the development of the ATM technology.The ATM inverse multiplexing technology is a rising task. IMA (Inverse Multiplexing ATM) introduces the inverse multiplexing operation mechanism which is contrary with the traditional ATM. In the traditional multiplexing, many low-speed data streams are assembled in one single high-speed channel at the transferring terminal, and the high-speed data stream is multiplexed reversely to many low-speed data streams at the receiving terminal. But the IMA technology combines some low-speed channels in one unitary logic channel. In this way, a big and unitary data stream can be decomposed into many low-speed data streams. At the receiving terminal, these decomposed data streams will be composed to the original data stream. The general way is to bond many low-speed channels of E1/T1 type to make a high-speed channel to transfer data. It can increase or decrease bandwidths flexibly, reduce the transfer risk and make the best of the bandwidth. In addition, inverse Multiplexing ATM (IMA) can compensate the data rate gap between the traditional E1/T1 and E3/T3, providing one economical and flexible data transfer method.This paper discusses the basic principle and the advantages of ATM and IMA technologies firstly, then introduces one receiving and transferring device designed using IMA mode with the VHDL programming language and Quartus 2 emulation software. One router supervisory control device is also designed to supervise these low-speed transmission channels. These two devices are realized by programmable logic control devices. If these two sets of equipment are used together, they are able to decompose and compose data effectively. They can also change transmission mode real timely based on the result of supervision of the transmission channels and avoid the data loss, simultaneously reporting a warning. The receiving and transferring device with the IMA function in the paper can transfer data stream of 6Mbit/s. The route supervisory control device can answer only one connection failure of the transmission channels.In addition, the program of CMOS chip in the paper can be easily changed to fit the different transmission speeds and different number of channels. Thus consumers can use this set of devices freely and flexibly according to their actual requirements, which improves the channel utilization ratio.