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To: rhet0ric who wrote (9192)	3/12/1998 6:12:00 PM
From: w molloy	Read Replies (3) \| Respond to of 152472

rhet0ric asks " My question had more to do with the protocol the Internet uses, TCP/IP, than the types of network that the protocol uses. Maybe I'm comparing apples to oranges,but I was asking about the difference between TCP/IP and CDMA or TDMA rather than between one network format and another. Maybe what you're saying is that CDMA and TDMA are network formats, not protocols." rhet0ric, To explain the difference between TCP/IP; CDMA and TDMA I have to delve into Protocol 'stacks'. I'll give a quick technical overview, followed by an analogy, which I hope illustrates the principle. Much telecommunications software these days is designed around the 'Open Systems Interconnect (OSI) Reference Model' developed by the International Standards Organisation (ISO). This model has 7 layers. There are a number of principles governing what a layer is but a key one is that each layer should perform a well defined function.In this model, TCP/IP fits in around Layer 4 and CDMA and TDMA are firmly in Layer 1. Layer 4 is the Transport layer, Layer 1 is the Physical layer. I should add that communication is between peers, that is my TCP/IP 'talks' to your TCP/IP, independent of what the underlying layers do. In this sense, TCP/IP doesn't care (and it shouldn't) whether you have a CDMA physical layer, a TDMA physical layer or indeed a bit of copper! Now my analogy. Tom can talk to Dick. The protocol they use - lets call it English. BUT, that isn't the end of the story. There is a physical connection, their respective larynxes produce variations in air pressure, which their ears pick up and their brains translate into speech. Lets keep this really simple and call it a two layer model : English; air pressure variation. Now lets add a layer - 2 paper cups and a piece of wet string. The lowermost layer changes from Air pressure to vibrations in the wet string. Note that the top level protocol doesn't change. This a key point. We can substitute the wet string for a telephone and still the top level protocol (English) doesn't change. In summary, your question regarding whether CDMA or TDMA is more suited for TCP/IP is moot, because TCP/IP is independent of the physical layer involved. w.