Greeting
Need help how to make multiple arduinos talk at same time without any data curruption
The problem is not in the "talking", but in the "listening". Who or what is listening to the multiple talklings?
Hello vyom_2010
We are talking about a full duplex connection?
YES full duplex listning and talking simaltanusly
yes is there any existing protocols which support multiple divices having duplex conversations simultanusly
In this case take some time and study Code-division multiple access modulation.
Is this a wired or wireless setup?
Do the devices all send & receive data to/from one central device, or do they talk to each other directly?
I am trying to do both the versions
is there any library for creating private cdma network
Take a search engine of your choice and ask the WWW.
i am doing same but no results thats why i asked you
If you were in a crowd of people all yelling at once, how many individual voices would you understand ? Would you understand any? Think about this in relation to your question.
I will be able to listen everyone but cant understand in fact it will be currupted thats why i want to use cdma
Greeting
I am unable to find any cdma library for Arduino for making private cdma network
if you already have an Arduino, you are on your way...
You are just missing a 5 figure investment (in US$) infrastructure stuff (like a good antenna and lots of software like a BTS, BSC, MSC, GGSN etc to handle data traffic) 
for software you could look at the new version of Open BSC ➜ [Osmocom CNI](Overview - Cellular Network Infrastructure - Open Source Mobile Communications
You'll get OsmoBSC, OsmoMSC, OsmoHLR, OsmoSTP, OsmoMGW - a NITB style setup is described at Osmocom_Network_In_The_Box.
or Look at picocell or Tecore if you want to purchase a solution (have a deep wallet ready), may be you can find used gears like an Agilent 8960 for "cheap" (it's a communications analyser that can be used for testing devices in production lines - make sure it has all the right software packages)
can you Elobrate
Building private cell phone wireless network is not something easy, there are lots of moving parts. (see Overview - Cellular Network Infrastructure - Open Source Mobile Communications)
Are you a wireless cellular network engineer? if not you have some reading to do before you attempt to do any of this. And it's costly.
if you want to create a local WiFi network, that's much easier 
actually i am not any engineer i am trying to make many arduino to conunicate without any disturbunce and simultanusly
I have merged your topics @vyom_2010 .
Please only create one topic for each distinct subject matter and be careful not to cause them to converge into parallel discussions.
The reason is that generating multiple threads on the same subject matter can waste the time of the people trying to help. Someone might spend a lot of time investigating and writing a detailed answer on one topic, without knowing that someone else already did the same in the other topic.
Thanks in advance for your cooperation.
The problem is that you are confusing several layers of the communications problem. At the physical layer - on the wire or in the ether - "multiple access" has to be solved by separating signals in time, frequency, or code, and "simultaneous" duplex communications is a horrendous problem especially if wireless. But existing protocols like Ethernet or Wi-Fi have solved this physical layer problem by adding higher "medium access control" layers. Higher layers still can create in effect simultaneous duplex communications between multiple devices that share the same physical connection. If you could formulate your problem more precisely you could see how these existing frameworks could be applied.