1. Same job, different names — the grand translation table
| Job | 2G GSM | 3G UMTS | 4G LTE | 5G |
|---|---|---|---|---|
| Phone | MS | UE | UE | UE |
| SIM | SIM | USIM | USIM | USIM (SUCI) |
| Radio site | BTS | NodeB | eNodeB | gNB |
| Radio controller | BSC | RNC | — (in eNB) | — (CU/DU in gNB) |
| Access network name | BSS / GERAN | UTRAN | E-UTRAN | NG-RAN |
| Control-plane core | MSC/VLR (CS), SGSN (PS) | MSC/VLR, SGSN | MME | AMF (+ SMF) |
| User-plane / anchor | GGSN | GGSN | SGW + PGW | UPF |
| Subscriber database | HLR + AuC | HLR + AuC | HSS | UDM + UDR + AUSF |
| Policy / charging | (SCP / IN) | PCRF (later) | PCRF + OCS | PCF + CHF |
| Voice | CS (MSC) | CS (MSC) | VoLTE (IMS) or CSFB | VoNR or EPS Fallback |
| SMS | MAP via MSC | MAP via MSC | SGs or SMS-over-IP (IMS) | SMS over NAS (SMSF) or IMS |
| Main signalling | SS7 / BSSAP / MAP | SS7 / RANAP / MAP | Diameter, S1AP, GTP-C | HTTP/2 SBI, NGAP, PFCP |
| Data tunnel | GTP | GTP | GTP-U | GTP-U |
| Data session | PDP context | PDP context | EPS bearer (PDN connection) | PDU session / QoS flow |
| Data name | APN | APN | APN | DNN |
| Security algorithms | A5/1, A5/3 | KASUMI (UEA1/UIA1), SNOW3G (UEA2) | EEA/EIA (SNOW3G, AES, ZUC) | NEA/NIA (AES, SNOW3G, ZUC) |
| Auth | A3/A8 (SIM only) | AKA (mutual) | EPS-AKA | 5G-AKA / EAP-AKA' |
| Temp ID | TMSI | TMSI / P-TMSI | GUTI | 5G-GUTI |
| Area for paging | Location Area | LA / RA | Tracking Area | Registration Area (TA list) |
| Radio multiplex | TDMA/FDMA | WCDMA | OFDMA / SC-FDMA | OFDMA (CP-OFDM) |
| Channel | 200 kHz | 5 MHz | up to 20 MHz | up to 100 MHz (FR1) / 400 MHz (FR2) |
| Typical peak rate | ~0.2 Mbit/s | 2–42 Mbit/s | 100 Mbit/s – 1 Gbit/s | 1–20 Gbit/s |
| Latency (radio) | ~500 ms | ~100 ms | ~10–30 ms | ~1–10 ms |
2. Speed and latency in plain words
| Gen | Downloading a 1 GB film |
|---|---|
| GPRS (~50 kbit/s) | ~44 hours |
| EDGE (~200 kbit/s) | ~11 hours |
| 3G UMTS (~2 Mbit/s) | ~1 hour 10 min |
| HSPA+ (~20 Mbit/s) | ~7 min |
| LTE (~100 Mbit/s) | ~1.5 min |
| 5G (~1 Gbit/s) | ~8 s |
3. Which protocol, which pair of nodes? (memorise these)
| Pair | 2G/3G | 4G | 5G |
|---|---|---|---|
| Phone ⇄ core (NAS) | MM/CC/SM | EMM/ESM | 5GMM/5GSM |
| Radio ⇄ core (control) | BSSAP / RANAP | S1AP | NGAP (N2) |
| Radio ⇄ core (user) | Iu-PS / Gb | S1-U (GTP-U) | N3 (GTP-U) |
| Visitor ⇄ home DB | MAP (D interface) | Diameter S6a | HTTP/2 Nudm |
| Call between switches | ISUP | SIP | SIP |
| Core control ⇄ gateway | GTP-C (Gn) | GTPv2-C (S11, S5) | PFCP (N4) |
| Policy | — | Diameter Gx | HTTP/2 Npcf |
| Charging | CAP / Ro | Diameter Gy/Ro | HTTP/2 Nchf |
4. Order of magnitude numbers
- GSM frame: 8 time slots, slot 0.577 ms, frame 4.615 ms; E1 = 2.048 Mbit/s (30 channels).
- GSM channel 200 kHz; UMTS 5 MHz; LTE 1.4–20 MHz; NR 5–100 MHz (FR1), 50–400 MHz (FR2).
- GSM cell range max 35 km (timing advance 0–63); LTE range depends on band and cell (up to ~100 km, usually 1–10 km); mmWave ~100–300 m.
- SMS: 140 bytes: 160 GSM-7 chars / 70 UCS-2 chars; concatenated parts 153 / 67.
- IMSI: 15 digits max; MSISDN: 15 digits max; IMEI: 15 digits.
- Voice call bit rate: AMR 12.2 kbit/s, AMR-WB 12.65–23.85, PCM (landline) 64 kbit/s.
- VoLTE: QCI 1 (voice), QCI 5 (IMS signalling), QCI 9 (default internet).
- 5G: 5QI 1 voice, 5QI 9 default, SST 1/2/3/4 = eMBB/URLLC/MIoT/V2X.
5. Timeline
| Year | Event |
|---|---|
| 1973 | First handheld mobile call (Motorola) |
| 1979–83 | First commercial 1G networks (Japan, Nordics, USA) |
| 1991 | First GSM call in Finland (2G) |
| 1992 | First SMS ("Merry Christmas", Neil Papworth) |
| 1999–2001 | GPRS, then first 3G networks (Japan 2001) |
| 2007 | iPhone; HSPA makes mobile internet mainstream |
| 2009–10 | First LTE networks (Stockholm, Oslo) |
| 2012 | First commercial VoLTE (SK Telecom and LG U+ in South Korea, MetroPCS in the US, Aug 2012) |
| 2018–19 | First commercial 5G: US fixed-wireless (Oct 2018), South Korea (Dec 2018), phones widely from 2019 (NSA) |
| 2020–22 | 5G SA launches, VoNR |
| 2024–25 | 5G-Advanced (Rel-18), early 2G/3G shutdowns spread |
| ~2030 | 6G expected |
6. "If you see this, think this"
| You see… | Think… |
|---|---|
SRI, SRI-SM, PRN, UL, ISD |
MAP — 2G/3G mobility; check HLR |
ULR, AIR, CLR, IDR on S6a |
4G Diameter to HSS |
Create Session Request |
GTPv2 — 4G data session |
Registration Request, PDU Session Establishment |
5G NAS (AMF/SMF) |
INVITE, 180, 200 OK |
SIP — VoLTE/VoNR call |
IAM, ACM, ANM, REL |
ISUP — circuit call |
submit_sm, deliver_sm |
SMPP — A2P SMS |
MO-ForwardSM, MT-ForwardSM |
MAP SMS |
Attach reject cause 7/8 |
EPS service not allowed / no EPS service |
PFCP Session Establishment |
5G N4, SMF → UPF |
Nudm_UEAuthentication_Get |
5G authentication |
cause 17 |
User busy |
Remember this: you now have the ladder 1G → 5G, the translation table between generations, and the six door-protocols of the interconnect. The rest of the course is details on top of this frame.