Reason for four frame types in Wireless LAN

Question

So I was asked this question in an interview as a junior network specialist the other day:

Give A reason why there is only one frame type in a wired LAN but four frame types in a wireless LAN.

This was my answer:

The reason for having only one frame type in a wired LAN is due to the fact that they are self-identifying. Due to this reason they are able to intermix various protocols while using the same physical network and makes it possible to allow a single sender to utilize various protocols together and still transmit the data over the medium.

But for wireless LAN my brain went numb, but was I saying the right thing?

Answer 1

Well, the real answer (according to 802.11, which I helpfully downloaded yesterday)..

There are 4 frame types, and they are: Management, Control, Data, and "Reserved".

Unsurprisingly, Reserved types appear not to be used (yet!).

Management frames include stuff like Beacon announcements, Association/Dissociation messages, Probe requests and responses and so on.

Control frames actually control the data-link and supply RTS/CTS flow control information.

Data frames hold the data, unsurprisingly, but also cover things like QoS levels and traffic management.

This snippet (1):

A STA shall be able properly to construct a subset of the frames specified in this clause for transmission and to decode a (potentially different) subset of the frames specified in this clause upon validation following reception.

Effectively implies that a base station will be able to construct a subset of the full list of frames, but might only decode types relevant to itself.

The Explain it like I'm 5 answer is:

Because there are so many varying roles an access point/ router/ base station can take (referred to generally as a STA), there are frame types which are only relevant for certain roles. As a result, there's a kind of "routing" where only relevant roles will decode the frames relevant for them.

The "real" definition for a STA is:

fixed, portable, and moving stations (STAs) (2)

(1) : Page 380, IEEE 802.11 specification 2012

(2) : Page 1, IEEE 802.11 specification 2012