What is CSMA CA vs CSMA CD?

Is the CSMA/CD still used?

How did it start?

I'm pretty sure I'm going to get called out on this question, but it's worth asking. I've read a lot of articles about the various methods of contention resolution that have been used over the years, and it seems like CSMA/CD is still very common. However, I'm having a hard time finding information on how it started. Did the IEEE develop the CSMA/CD protocol? If so, where? Or was it a modified version of something else?

The IEEE is not the only organization that develops standards. In this case, the IEEE did not write the standard. It was written by researchers at Nippon Telegraph and Telephone (Nippon) in Japan. The IEEE published it in 1969 and that was the end of the story.

IEEE Transactions on Communications, Volume 1, Issue 1, January, 1969, pp 3-15, entitled "The Asynchronous Transfer Mode (ATM)" describes the standard. The authors were Shigenobu Nishikawa, Masatoshi Sugeno, and Tomohiro Nishiyama. (I've seen the paper listed as Sugeno et al.)
It's very difficult to get reliable information about this type of thing. I'm guessing the IEEE website is correct, but I can't find a reference to the IEEE. I also can't find any other references that back up the IEEE version. The IEEE does not have a "History" page on their site.

Yes, it's still in use. Wikipedia has an entry for it: Some of the links on that page link to the original IEEE paper: There are more links on that page that are linked to some more papers.

What is CSMA CA vs CSMA CD?

A quick question about CSMA/CA vs.

CSMA/CD, and how they are different. I am familiar with the fact that CSMA/CA is a way to share a single channel for many different users, while CSMA/CD uses an exclusive channel. Is this correct? Does CSMA/CA use a broadcast channel?

We have 10 nodes (with their own mac address) in a 100 mW network. We have two radios, each node sends data over the network when data is to be sent. We want the best reliability. What is better: CSMA/CA or CSMA/CD?
From what you've said, it sounds like you've read up on the basics of wireless networking. CSMA/CA is a collision-based protocol. CSMA/CD is a carrier sense-based protocol. I'll try to answer your question with some details.

In a sense, CSMA/CA can be seen as a more mature version of CSMA/CD. It was introduced in the mid-1980s, and has been evolving ever since. CSMA/CD was introduced in 1976, and was pretty much a re-write of earlier protocols (and in some ways still is).

The first step in CSMA/CA is a master/slave setup. The slave device "claims" a channel, while the master device listens. When the slave transmits, the master acknowledges. If the master doesn't acknowledge, the slave knows that it can transmit, as the master would've heard the signal. When the master transmits, the slave listens, and when the master transmits again, the slave acknowledges. In this sense, the devices are "talking" to each other, and each device is "listening" for the other to talk.

With CSMA/CA, the master device doesn't listen to all the signals coming into the channel; it only listens to the slave device that is transmitting. Thus, the master device doesn't have to listen for itself, as the slave device has already announced its intent to transmit.

So, how does it work? Let's say that you have five devices. The first one transmits. If the second one wants to transmit, it will get a negative acknowledgment back from the first one.

Is CSMA an Ethernet?

What does Carrier sense multiple access with collision detection mean?

I understand that CSMA means Carrier Sense Multiple Access (multiple node-to-node communications), but how does this relate to Ethernet? As far as I know, if a switch receives a packet/frame then it would process the frame before sending it on its port/output; it wouldn't be sent on more than one node until a collision is detected. What does "carrier sense" do then? In Ethernet, all nodes try to transmit their frames in a synchronous way, so any collisions would occur during the same time windows of all nodes. So yes, we are talking about the same concept here. We just rename it to reflect Ethernet's terminology.

As said, CSMA is a mechanism that allows nodes to determine if they are sending a frame, and thus the destination of the frames themselves. There is no explicit notion of a "time window" where we can check if any collision has occurred. That's why CSMA is a "multiple access" mechanism, because not all nodes transmit frames at the same time.