Can we broadcast Music using wifi broadcast and listen to thhe same on devices supporting monitor mode. I would like to listen on monitor mode because I expect the number of devices getting connected is too high for wifi to work properly using IP-protocol. I want the wifi device to act as a FM broadcast where every device recieves every packets and stream the music.
Are you talking about this Wifibroadcast , here?
If so: well yes, monitor mode is the underlying technology, as can be seen here.
Now, if this is about doing a commercial product, sadly, you cannot expect any kind of interoperability from this.
Streaming audio/video over Wi-Fi is a business, and the the power in charge (Wi-Fi Alliance aka WFA) as some view on it, including certification programs. Have a look at Miracast, using Wi-Fi Direct.
As for multicast / broadcast, it is even more of a business and the realm of proprietary technologies for now (example here - and no, this is not limited to automobile). This is quite complicated, to start with because of the synchronization problem across receivers: you don't want 2 radio receivers in the same room to play with a 1 seconds delay, this would be cacophony.
EDIT:
Meaning, be it with the Wifibroadcast OSS project or with the proprietary industry about it, since there is not yet an open protocol for this (as "publicly available standard specification", I don't even go about implementation, FLOSS or not), you will have to provide a specific application for every receiver to match your broadcaster protocol, and vice versa. And that is the state of the industry today. That is what the company I mentioned above, or this other one more well know, or these are doing. And so, they do not interoperate. This will be your problem: provide a receiver app for Windows, Mac OS, Android and iOS (where you may not even have access to sub-layer 3 API) that will match your radio broadcaster protocol. And Linux too, please.
Though, this is the direction of history because this is what the user wants: stream A/V to/from device/application X from brand A to device/application Y from brand B.
And so people have been working on this, on layer 2, because layer 3 and above have unsolvable challenges with it, at IEEE since 2004 with Ethernet AVB, which is a set of protocols. You can download some of its standards for free, others for a moderate fee depending on how old they are. There is a SIG taking care of certification(http://avnu.org/certified-products/) to guarantee interoperability.
It is for 802.3 (aka wired Ethernet), but there is some work done to bring this to 802.11 Wi-Fi. Because again, that's what the user wants, the market is here, no question about that. It will take a long time. Even more to get consumer electronic grade devices or applications of the shelves. But they will interoperate out of the box, that's the goal.
There's even been work done on moving this to layer 3/IP as well BTW, with some performance sacrifice.
So come back in a few years, and all should be setup. Or, if you have lots of time and money and no urge to deliver, implement a solution based on these standards?
PS:
Link to AVnu (Ethernet AVB SIG) page about use cases for consumer electronics audio streaming, wired or wireless:
...and its 10 pages white paper at the bottom of the page.