2 The six groups, and what each one worries about

2.1 Six different questions

Before a phone works on a strange network, six quite different things have to be settled, and RAN has one room for each.

2.2 RAN1 — the signal

What is sent over the air, in what shape, at what moment. RAN1 holds 66 active documents RAN1 ^[1].

Four of them describe the 5G air interface between them: 38.211 for channels and modulation, 38.212 for channel coding, 38.213 for control procedures, 38.214 for data procedures TS 38.211 TS 38.212 TS 38.213 TS 38.214.

2.3 RAN2 — the conversation

What the phone and the base station say to each other once the radio works. 62 active documents RAN2 ^[2].

Its central document is 38.331, which defines every message of the radio connection, with the three layer-2 protocols 38.321, 38.322 and 38.323 beneath it TS 38.331 TS 38.321 TS 38.322 TS 38.323.

RAN2 also owns 38.300, the overall description this course reads TS 38.300.

2.4 RAN3 — the wires between the boxes

How one base station talks to another and to the core network. 168 active documents RAN3 ^[3].

It holds 38.401, the architecture description, and three interface protocols: 38.413 towards the core, 38.423 between base stations, 38.473 inside a base station that has been split up TS 38.401 TS 38.413 TS 38.423 TS 38.473.

2.5 RAN4 — what can be measured

Transmit power, receiver sensitivity, how quickly a phone must find a neighbouring cell. 427 active documents, more than any other group in RAN RAN4 ^[4].

Three carry most of the weight: 38.101-1 for what a phone's radio must do, 38.104 for a base station's, and 38.133 for radio resource management requirements TS 38.101-1 TS 38.104 TS 38.133.

2.6 RAN5 — the exam board

The test cases a phone has to pass. 84 active documents RAN5 ^[5].

Four mark out the exam: 38.508-1 for common test settings, 38.521-1 for radio transmission tests, 38.523-1 for protocol tests, 38.533 for radio management tests TS 38.508-1 TS 38.521-1 TS 38.523-1 TS 38.533.

2.7 RAN6 — the closed room

RAN6 held the old GSM radio work. 54 active documents, and no meetings since 2020 RAN6 ^[6].

Its last was a single day, by telephone, on 2020-10-26 3GPPRAN6#18-Decision Teleconference. The renumbered GSM documents did not move to another working group; they went up to the plenary, 179 documents from the 3G and GSM series in all ^[7].

2.8 In one table

Group	The question it answers	A document that marks it
RAN1	What is sent over the air?	38.211
RAN2	What do the two ends say?	38.331
RAN3	What do the boxes say to each other?	38.423
RAN4	How well must the radio perform?	38.133
RAN5	How is a phone proved to comply?	38.523-1
RAN6	The old GSM radio (closed)	—

2.9 They are nothing like equal

RAN4's 427 documents against RAN2's 62 is not a measure of how many rules each group writes. 352 of RAN4's are study reports rather than specifications, because radio performance is worked out band by band and each band brings homework ^[8].

RAN5 is the other shape: 72 of its 84 are specifications ^[9]. An exam board writes rules, not essays.

By people the order changes again. 710 sat in the room at RAN1#125 ^[10], against 426 at RAN2's meeting the same week ^[11] and 202 at RAN3's ^[12].

2.10 One thing that catches everybody out

The overall description is written by one group about everybody else's work. TS 38.300 belongs to RAN2, and yet its physical-layer clause is RAN1's material and its interface clause is RAN3's TS 38.300 §5 §4.3.

Owning the map is not owning the ground. The overall description says itself that the details live in companion documents of the 38 series §1, and those companions mostly belong to other rooms.

What those rooms actually produced is What NR is, read off the document itself.