What many maybe didn't know is that ALOHA (Aloha) is so much more than just a simple useless Hawaii phrase used after a forum post.
Actually, it has a much longer history to it than people think and it was the first so called random access method that was developed in University of Hawaii in the early 1970's. It was designed for radio LAN but it can be used on any shared medium.
When several stations shares the same medium it is obvious that there are potential collisions on this type of arrangement. It was one of the flaws with ALOHA but neither the less it was the type of protocol of that sort that everything else is based on.
It was the big pioneer of this type of communication protocols!
So when a station sends data on the line, another station may attempt to send their data too at the same time and then the data from the two stations collide and become garbled.
Here's a small lecture on ALOHA that will cheer you up.
As you can see, to assess Pure ALOHA, there is a need to predict its throughput and rate of (successful) transmission of frames.
The probability during any particular period would then be t=(2n+1)T to t=(2n+2)T
wheras the probability that both the independent events will occur simultaneously is
But if you would consider N nodes attempt to send data at time T, you would have to make the simple calculation of the probablity of a successful transmission on the nod:
So below you see an example of different troughputs, where S reaches peak value of 1/e = 0.368 at load G = 1
which proves that all frames do follow Tanenbaum. Very important.
