Every question of this course

Q1.1 How many working groups sit under the RAN plenary, and how many of them still meet?

• Five working groups, all five still meeting
• Six working groups, five of them still meeting
• Six working groups, all six still meeting

The group catalogue lists RAN1 to RAN6. RAN6 is the only one it marks as closed, so five are still running. RAN6

Q1.2 What does the RAN plenary do besides chairing the working groups?

• It writes the physical layer itself
• Nothing — it only approves what the groups send up
• It owns documents of its own, 198 active ones

The plenary is a document owner in its own right. The local catalogue puts 198 of RAN's 1059 active documents in the plenary's own hands. 198 active RAN plenary specifications

Q1.3 How many of the 3599 active 3GPP documents does RAN own?

• 3230
• 1059
• 198

RAN owns 1059 active documents out of 3599 for all of 3GPP. 198 of those 1059 are the plenary's own; 3230 is the number of pieces of work a RAN plenary document has opened. 3599 active 3GPP specifications in total

Q1.4 What does TS 38.300 say it covers?

• Every message the radio protocols exchange, byte by byte
• An overview and overall description of the NG-RAN, focused on the radio interface protocol architecture
• The 5G core network and its functions

The scope says it is an overview and overall description, and that the details of the radio interface protocols live in companion specifications of the 38 series. §1

Q1.5 A colleague says "RAN has never written anything about GSM." Is that right?

• No — the plenary holds 179 active documents from the 3G and GSM series
• No, but only RAN6 ever touched them
• Yes, GSM was always somebody else's job

The renumbered GSM documents sit with the plenary, not with the closed RAN6, and there are 179 of them from the 3G and GSM series. 179 active documents the RAN plenary holds from the 3G and GSM series

Q2.1 Which group owns the four documents that describe the 5G air interface — 38.211, 38.212, 38.213 and 38.214?

• RAN1
• RAN2
• RAN4

RAN1 is the layer 1 group, and those four are channels and modulation, channel coding, control procedures and data procedures. TS 38.211

Q2.2 A document defines every message of the radio connection between phone and base station. Which group owns it?

• RAN2, which owns 38.331
• RAN3, because it is a protocol
• RAN1, because the messages travel over the air

38.331 is the radio connection protocol and belongs to RAN2, together with the three layer-2 protocols 38.321, 38.322 and 38.323. TS 38.331

Q2.3 Which group has by far the most active documents?

• RAN3, with 168
• RAN4, with 427
• RAN1, with 66

RAN4 owns 427 active documents, more than any other group in RAN. RAN3 is the next largest working group with 168. 427 active RAN4 specifications

Q2.4 What does RAN5 produce?

• The test cases a phone has to pass
• The transmit-power limits a base station must obey
• The architecture of a split base station

RAN5 is the conformance testing group. Transmit power is RAN4 and the split architecture is RAN3. RAN5

Q2.5 What is the state of RAN6?

• It meets alongside the other groups every quarter
• It is closed; its last meeting was on 2020-10-26
• It never existed as a separate group

RAN6 held the old GSM radio work. The catalogue marks it closed and the meeting record ends with a one-day telephone meeting on 2020-10-26. 3GPPRAN6#18-Decision Teleconference

Q2.6 Which group would you go to about the connection between one base station and another?

• RAN2, since it owns the radio protocols
• RAN3, which owns the interface protocols including 38.423
• RAN4, which measures everything

RAN3 owns the wires between the boxes — 38.413 to the core, 38.423 between base stations, 38.473 inside a split base station. TS 38.423

Q3.1 By active documents, which group is largest? And by people in the room?

• RAN1 by both
• RAN4 by both
• RAN4 by documents, RAN1 by people

RAN4 holds 427 active documents against RAN3's 168, but RAN1 filled the room with 710 people at RAN1#125, more than any other RAN meeting counted here. 710 people sat in the room at 3GPPRAN1#125

Q3.2 How many of RAN4's 427 active documents are study reports rather than specifications?

• 352
• 12
• 75

352 of the 427 are study reports. RAN4's paper output is mostly homework, band by band. 352 active RAN4 study reports (TR)

Q3.3 The 38 series holds 264 active documents. Who owns most of them?

• The plenary
• RAN2, since it owns the overall description
• RAN4, with 138 — more than RAN1, RAN2 and RAN3 together

RAN4 holds 138 of the 264, which is more than the three drafting groups above it hold between them. 138 active 38-series documents owned by RAN4

Q3.4 How many RAN meeting documents does the local database hold?

• 3230
• 811563
• 55270

811563 RAN meeting documents are in the local database. 55270 of them are the plenary's own and 3230 is the number of separate pieces of work a plenary document opened. 811563 RAN meeting documents in the local database

Q3.5 Somebody quotes a per-group document total as exact. What is the honest caveat?

• Three active rows carry no usable group, so the totals are very good rather than proven
• The totals are guesses with no source
• There is none; the catalogue is complete

Three active rows in the catalogue have no usable group. Everything else is read straight from the data, so the numbers are close but not provable to the last document. 3 active catalogue rows carry no usable group

Q4.1 What are the two kinds of node an NG-RAN can be built from?

• A base station and a router
• A gNB and an ng-eNB
• A gNB and an AMF

A gNB gives the device NR user plane and control plane terminations; an ng-eNB gives it E-UTRA terminations. Both are NG-RAN nodes. §4.1

Q4.2 Which interface joins two base stations to each other?

• NG
• Xn
• Uu

The gNBs and ng-eNBs are interconnected by the Xn interface, and connected to the core by the NG interfaces. §4.1

Q4.3 What is the difference between the user-plane and control-plane halves of the NG interface?

• NG-C carries the packets and NG-U the signalling
• There is no difference; both use the same protocol
• NG-U carries packets with non-guaranteed delivery; NG-C runs a signalling protocol over SCTP with guaranteed delivery

NG-U uses GTP-U over UDP/IP and provides non-guaranteed delivery. NG-C adds SCTP for reliable transport and carries NGAP. §4.3.1.2

Q4.4 How is the subcarrier spacing of NR defined?

• A single fixed value of 15 kHz
• Exponentially scalable, 2 to the power µ times 15 kHz
• Freely chosen by the operator

The numerology scales exponentially, and twelve consecutive subcarriers make one physical resource block. §5.1

Q4.5 How long is a radio frame, and what is it made of?

• 1 ms, of ten slots
• 100 ms, of ten frames
• 10 ms, of ten 1 ms subframes

Frames are 10 ms and hold ten 1 ms subframes, split into two equal half-frames of five subframes each. §5.1

Q4.6 Does NR use UE categories with fixed peak data rates?

• Yes, and they are signalled to the network
• No — categories are for marketing only and are not signalled
• Yes, but only for base stations

Capabilities are reported per band and per band combination instead. The document says categories exist for marketing purposes and are not signalled. §14

Q5.1 Which four sublayers is layer 2 of NR split into?

• MAC, RRC, IP and TCP
• PHY, MAC, RLC and RRC
• MAC, RLC, PDCP and SDAP

RRC is layer 3 and the physical layer is layer 1. Layer 2 is exactly those four sublayers. §6.1

Q5.2 Which sublayer maps a QoS flow onto a data radio bearer?

• PDCP
• SDAP
• MAC

SDAP does the mapping and marks the QoS flow ID in both directions. One SDAP entity is configured per PDU session. §6.5

Q5.3 In which RLC mode is ARQ — retransmission based on status reports — available?

• Acknowledged Mode only
• All three modes
• Transparent Mode only

RLC has Transparent, Unacknowledged and Acknowledged modes. Error correction through ARQ is listed for Acknowledged Mode only. §6.3

Q5.4 In RRC_INACTIVE, where is the device's context kept?

• Only in the device
• Nowhere; it is thrown away and rebuilt on the next connection
• At the last serving gNB, together with the connection towards the core

The last serving base station keeps the context and the connection to the core, which is what makes resuming cheap. §9.2.2.1

Q5.5 A device moves inside its RAN-based notification area while in RRC_INACTIVE. What must it do?

• Nothing — it may move within that area without telling the network
• Report every cell change
• Return to RRC_CONNECTED first

The whole point of the area is that movement inside it needs no signalling. Leaving it triggers an update. §9.2.2.1

Q5.6 Where is RRC signalling ciphered and integrity-protected?

• At the UPF
• At the AMF
• At the gNB

The termination table puts NAS signalling at the AMF, and both RRC signalling and user plane data at the gNB. §13.2

Q6.1 What is the first document in the life of a new piece of RAN work?

• A study item description put to the plenary
• A liaison statement
• A change request

The plenary is asked to open a study first. 737 such documents are in the local database. 737 RAN meeting documents of type 'SID new'

Q6.2 Of the 3230 pieces of work a RAN plenary document opened, how many are studies?

• 1615
• 3230
• 217

217 of the 3230 are recorded as studies. Most opened work is not a study but real specification work. 217 of the RAN work items are studies

Q6.3 Once a specification is published, how is it changed?

• By the working group editing it directly between meetings
• By a new version written from scratch
• Only by change request, and the plenary approves them in bundles

The change request is the only route in, and 7012 change request packs show the plenary approving them in bundles rather than one at a time. 7012 RAN meeting documents of type 'CR pack'

Q6.4 Which is the commonest kind of RAN meeting document?

• Liaison statements, at 20742
• Change requests, at 190421
• Discussion papers, at 257341

257341 documents are marked simply "discussion" — more than all the change requests together. A RAN meeting is mostly argument. 257341 RAN meeting documents of type 'discussion'

Q6.5 Which document has been changed most often in RAN?

• 38.300, the overall description
• 38.331, the radio connection protocol
• 38.133, RAN4's radio resource management requirements

18987 documents change 38.133, ahead of 38.331 with 11787 and 38.101-1 with 9008. 18987 RAN documents change 38.133

Q6.6 One group needs an answer from another. What does it send?

• A work item description
• A liaison statement — a letter from one group to another
• A change request against the other group's specification

20742 outgoing liaison statements are in the local database. Two of them, R1-2603888 and R2-2602996, are the same question in two rooms. 20742 RAN meeting documents of type 'LS out'

Q7.1 How often does the RAN plenary meet, and for how long?

• Twice a year, for two days
• Four times a year, usually four days
• Once a month, for a week

The recorded plenaries run 2025-06-09, 2025-09-15, 2025-12-08, 2026-03-09 and 2026-06-08, usually over four days. 3GPPRAN#112

Q7.2 When do the five open working groups meet?

• Only when the plenary calls them
• Each in its own week, spread over the quarter
• All in the same week, in the same place, for five days

All five met from 2026-05-18 to 2026-05-22 in China. Meeting together is what makes a letter between two groups answerable in days. 3GPPRAN1#125

Q7.3 What is a "bis" week?

• The second half of a plenary
• A meeting held only by telephone
• An extra working-group week between two ordinary ones

RAN1, RAN2, RAN3 and RAN4 all met again from 2026-04-13 in Saint Julian's. RAN5 does not take the extra week. 3GPPRAN1#124-bis

Q7.4 Which working group skips the extra week?

• RAN1
• RAN5
• RAN3

RAN5's meetings run 2026-02-09 then 2026-05-18, with nothing in April. 3GPPRAN5#110

Q7.5 The record says a document was "not pursued". What may you write about why?

• That the proposal lacked support
• That the plenary ran out of time
• Nothing — the data carries the status and never the reason

A status is approved, revised, noted, withdrawn or not pursued, and stops there. Any reason would be invented. RP-261197

Q7.6 Somebody asks who chaired RAN4 last year. What does this register hold?

• No name at all — only companies and roles are recorded
• The name, but only for closed groups
• The name, from the attendance list

No person is named anywhere in the data. It carries a company or a role, such as "Nokia" or "ETSI MCC", and never a human being. address of one group's chair history