Question

Hi

I have an assignment that has this question basis on network protocols (multiple access protocols):

Q1 ) Explain why collision is an issue in random access protocols but not in channelization protocols?

I need an explanision for that question

Answer 1

Collision is a case in which one station's data overlap with another station's data and both station's data become useless.

In random access protocol, channel (communication link) is not divided between stations and no central access mechanism is available to access the channel.

Hence user(station) can send or transmit a data any time it wants or it has a data to send. Suppose station A is already transmitting a data. Now station B got the data it want to transmit.Station B immediately start transmitting a data on the channel that is already occupied by station A.hence station B's data colied with station Station A's data and collision occurs.

Basically three types of random access protocol are available.1) Pure Aloha 2) slotted Aloha 3) CSMA(Carries sense multiple access)

While in the case of channelization protocol channels are partitioned into number of pieces or slot (according to multiplexing scheme), each peice is given to each individual station to transmit a data.

So each station can use only that piece of the channel to transmit a data. The station cannot allow to transmit data on other channel's slot. So there is no case of collision in Channelization.

There are three multiplexing schemes according to which channels are divided, 1) Time division multiplexing 2) frequency division multiplexing and 3) Code division multiplexing.

Hope you got your answer if you want any further explanation or information regarding this please let me know by leaving comments.