Voici un QCM (35 questions) basé sur le PDF que tu as envoyé. (IR_Final_all_compressed-114-248.pdf)
(1 seule bonne réponse par question.)

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QCM – Réseaux mobiles (1G → 3G) + WDM + FTTx

Q1. La 1G a été conçue principalement pour :
A) La vidéo en streaming
B) La voix analogique
C) Les SMS
D) L’Internet mobile

Q2. La technique d’accès multiple typique en 1G est :
A) TDMA
B) CDMA
C) OFDMA
D) FDMA

Q3. La modulation utilisée pour la voix en 1G (dans le cours) est :
A) QPSK
B) 16-QAM
C) FM
D) GMSK

Q4. Dans l’architecture 1G, l’élément qui connecte les BTS au réseau téléphonique classique est :
A) HLR
B) MSC
C) RNC
D) SGSN

Q5. En 1G, la largeur de bande typique d’un canal est :
A) 5 MHz
B) 200 kHz
C) 25–30 kHz
D) 1.25 MHz

Q6. FDD signifie :
A) Frequency Division Duplex
B) Fast Data Delivery
C) Full Digital Dispatch
D) Frequency Dynamic Division

Q7. Le FOCC (AMPS) est un canal :
A) Mobile → Base, uniquement voix
B) Base → Mobile, signalisation (infos système, paging, affectation)
C) Mobile → Base, signalisation (encryption)
D) Base → Mobile, uniquement données IP

Q8. Parmi les dimensions de planification, laquelle fait partie du “top 4” présenté ?
A) Coût CAPEX
B) Densité d’appareils
C) Consommation énergétique
D) Qualité vidéo

Q9. En 1G, la priorité de conception (dans le cours) était surtout :
A) La latence
B) La capacité data
C) La couverture
D) Le slicing

Q10. La distance de réutilisation en 1G est donnée par :
A) $D = R \sqrt{N}$
B) $D = R \sqrt{3N}$
C) $D = \frac{R}{\sqrt{3N}}$
D) $D = 3RN$

Q11. La 2G marque surtout la transition vers :
A) L’analogique
B) Le tout-IP
C) Le numérique (voix + SMS)
D) La 5G NR

Q12. Un apport clé de la 2G (GSM) absent en 1G est :
A) La modulation FM
B) La carte SIM (identité + authentification)
C) Le FDMA
D) La PSTN

Q13. Dans GSM, l’élément qui gère plusieurs BTS est :
A) BSC
B) GMSC
C) EIR
D) UE

Q14. La base qui contient les infos permanentes d’abonné + zone de localisation actuelle est :
A) VLR
B) HLR
C) AuC
D) EIR

Q15. L’EIR sert surtout à :
A) Stocker les clés de chiffrement A5
B) Générer des numéros aléatoires de challenge
C) Suivre les équipements valides/volés via IMEI
D) Router les paquets IP vers Internet

Q16. En GSM (2G), l’espacement/largeur de canal typique est :
A) 25 kHz
B) 30 kHz
C) 200 kHz
D) 5 MHz

Q17. Un carrier GSM est découpé en :
A) 4 time slots
B) 6 time slots
C) 8 time slots
D) 16 time slots

Q18. Le RACH sert principalement à :
A) Diffuser l’ID cellule et la liste des voisins
B) Paginer un mobile en downlink
C) Permettre au mobile de demander l’accès (uplink)
D) Transporter la voix (TCH)

Q19. Le canal souvent utilisé pour authentification / location update / call setup / SMS (signalisation dédiée) est :
A) BCCH
B) SDCCH
C) PCH
D) TCH

Q20. Le TMSI est :
A) L’identité permanente sur la SIM
B) Une identité temporaire attribuée par le VLR pour protéger l’IMSI
C) Une clé de chiffrement A5
D) Un identifiant d’équipement (IMEI)

Q21. IS-95 (cdmaOne) utilise typiquement un canal de :
A) 200 kHz
B) 1.25 MHz
C) 5 MHz
D) 20 MHz

Q22. Une particularité citée de l’IS-95 est :
A) Handover “soft” (connexion à plusieurs BTS)
B) 8 time slots par carrier
C) Modulation 8-PSK obligatoire
D) Architecture RNC + NodeB

Q23. Dans GPRS, le nœud qui gère mobilité/authentification et route les paquets côté radio est :
A) GGSN
B) SGSN
C) MSC
D) HLR

Q24. Dans GPRS, le nœud qui connecte vers les réseaux IP externes et attribue l’IP via PDP context est :
A) BSC
B) BTS
C) SGSN
D) GGSN

Q25. “PDP Context Activation” permet notamment :
A) D’assigner un canal voix TCH
B) D’obtenir une adresse IP et établir le tunnel vers le réseau externe
C) De faire du chiffrement A5
D) De changer la largeur de bande GSM à 5 MHz

Q26. En GPRS, les PDCH sont :
A) Des canaux voix réservés en permanence
B) Des time slots reconfigurés pour le trafic paquets
C) Des liens fibre entre BSC et MSC
D) Des codes d’étalement WCDMA

Q27. “TBF” (Temporary Block Flow) correspond à :
A) Un tunnel IP permanent
B) Un flux logique temporaire uplink ou downlink sur PDCH
C) Un canal de paging GSM classique
D) Une base de données d’abonnés

Q28. Le schéma de codage GPRS le plus robuste (débit le plus bas) est :
A) CS-4
B) CS-3
C) CS-2
D) CS-1

Q29. La sélection dynamique des coding schemes en GPRS se base notamment sur :
A) Température de la BTS
B) C/I et BER
C) Taille de l’écran du téléphone
D) Puissance du réseau PSTN

Q30. Une classe multislot Class 10 correspond (dans les exemples) à :
A) 4 DL + 2 UL (max 5 total)
B) 2 DL + 4 UL (max 6 total)
C) 1 DL + 1 UL (max 2 total)
D) 8 DL + 8 UL (max 16 total)

Q31. EDGE augmente le débit en introduisant notamment :
A) OFDMA
B) 8-PSK (en plus de GMSK)
C) FM analogique
D) NR (New Radio)

Q32. En EDGE, 8-PSK transporte :
A) 1 bit/symbole
B) 2 bits/symbole
C) 3 bits/symbole
D) 8 bits/symbole

Q33. La vitesse “max” par timeslot citée pour EDGE (MCS-9) est environ :
A) 9.6 kbps
B) 21 kbps
C) 59.2 kbps
D) 2 Mbps

Q34. UMTS/WCDMA utilise typiquement une largeur de canal de :
A) 200 kHz
B) 1.25 MHz
C) 5 MHz
D) 80 MHz

Q35. L’interface Uu en UMTS est entre :
A) NodeB et RNC
B) UE et NodeB
C) RNC et Core Network
D) SGSN et GGSN

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Corrigé (solutions)

1:B
2:D
3:C
4:B
5:C
6:A
7:B
8:B
9:C
10:B
11:C
12:B
13:A
14:B
15:C
16:C
17:C
18:C
19:B
20:B
21:B
22:A
23:B
24:D
25:B
26:B
27:B
28:D
29:B
30:A
31:B
32:C
33:C
34:C
35:B

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Si tu veux, je peux aussi te faire une version “examen” (sans corrigé), puis un corrigé séparé sur un autre message, ou augmenter à 50–60 questions en couvrant davantage WDM/FTTx et les exercices chiffrés.

Bien sûr ✅
Voici un résumé détaillé de la section 2.5G (GPRS) du PDF, en expliquant brièvement tout le contenu page par page, sans enlever les points importants. (IR_Final_all_compressed-114-248.pdf)

📌 La section 2.5G dans ton PDF correspond principalement aux pages 174 → 196 (environ), et elle traite surtout de GPRS (puis après ça commence EDGE = 2.75G).

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✅ Résumé détaillé — Section 2.5G : GPRS (Packet Data)

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📄 Page 174 — 2.5G: GPRS & EDGE (Packet Data)

Cette page introduit pourquoi on a eu besoin de 2.5G : (IR_Final_all_compressed-114-248.pdf)

• GSM (2G) était basé sur le circuit switching (optimisé pour la voix/SMS).
• Fin des années 1990, on a commencé à vouloir du mobile data :
  • Email
  • WAP browsing
  • MMS
• Les utilisateurs voulaient une connexion always-on (toujours active).
• Les opérateurs voulaient ajouter des données sans remplacer toute l’infrastructure GSM.
• Donc 2.5G = ajout d’une couche paquet (packet-switched overlay).
• C’est une étape de transition : réseau orienté voix → réseau orienté données.

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📄 Page 175 — GPRS (General Packet Radio Service)

Définition claire de GPRS : (IR_Final_all_compressed-114-248.pdf)

• Extension packet-switched ajoutée à GSM.
• Permet d’envoyer des paquets IP en plus de la voix/SMS.
• Appelé 2.5G parce que c’est entre :
  • 2G GSM (voix/SMS)
  • 3G UMTS (vrai Internet mobile)

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📄 Page 176 — Network Overlay

Cette page explique l’idée de “superposition” réseau : (IR_Final_all_compressed-114-248.pdf)

• GSM était conçu pour voice/SMS circuit-switching.
• GPRS ajoute un packet core network avec 3 éléments nouveaux :

✅ SGSN (Serving GPRS Support Node)

• Gère mobilité, authentification
• Route les paquets entre mobiles et réseau radio

✅ GGSN (Gateway GPRS Support Node)

• Connexion entre backbone GPRS et Internet / intranet
• Donne une adresse IP via le PDP context
• Joue le rôle de gateway router

✅ PCU (Packet Control Unit)

• Souvent dans le BSC, parfois BTS
• Gère les Packet Data Channels
• Coordonne avec SGSN

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📄 Page 177 — Architecture of GPRS (diagram)

Cette page montre un schéma complet de l’architecture : (IR_Final_all_compressed-114-248.pdf)
On remarque :

• La partie GSM classique :
  • BTS → BSC → MSC/VLR → PSTN
• Et en plus, la partie GPRS ajoutée :
  • PCU → SGSN → GGSN → Internet
• Donc la voix reste via MSC mais Internet passe via SGSN/GGSN.

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✅ Attachement & établissement de session (GPRS)

📄 Page 178 — Attach and Session Setup (1: Attach + 2: RA Update)

Explication du processus d’entrée d’un mobile dans le réseau paquet : (IR_Final_all_compressed-114-248.pdf)

1) GPRS Attach

• Le mobile envoie une demande Attach Request au SGSN
• SGSN vérifie les infos dans le HLR :
  • abonnement GPRS
  • APN autorisés
  • profil QoS

2) Routing Area Update

• Si accepté : SGSN stocke la localisation (Routing Area)
• Routing Area (RA) :
  • plus petit qu’une Location Area (LA, utilisée en voix)
• Le mobile met à jour sa position via RA update
  ➡️ Donc SGSN sait toujours où envoyer les données

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📄 Page 179 — 3: PDP Context Activation

C’est l’étape clé : ouvrir la “session data” : (IR_Final_all_compressed-114-248.pdf)

• PDP context = type de session vers réseau externe (Internet)
• Étapes :
  1. MS envoie Activate PDP Context Request
     • APN + QoS demandé
  2. SGSN transfère la demande à GGSN
  3. GGSN attribue une adresse IP
  4. SGSN confirme au mobile ✅ Résultat : le mobile a une identité IP + un tunnel logique vers Internet

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📄 Page 180 — 4: Always-On + 5: QoS and Billing

Après activation PDP : (IR_Final_all_compressed-114-248.pdf)

4) Always-On Session

• Mobile peut envoyer/recevoir des données sans “appeler”
• Session reste active jusqu’à désactivation
• Plusieurs PDP context possibles (Internet + VPN)

5) QoS & Billing

• QoS : delay, reliability, precedence, throughput
• Changement de facturation :
  • plus “minutes”
  • mais plutôt “MB”
• APN différents :
  • APN public : Internet
  • APN entreprise : intranet/VPN

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✅ Radio Resource Allocation (comment GPRS utilise les timeslots)

📄 Page 181 — Radio Resource Allocation (timeslots → PDCH)

Comparaison GSM vs GPRS : (IR_Final_all_compressed-114-248.pdf)

• En GSM : timeslot réservé en continu pour une personne (voix)

1) Timeslot Reconfiguration

• En GPRS : certains timeslots deviennent PDCH
• PDCH = pour des bursts data (pas stream voix)

2) Shared Access (Statistical Multiplexing)

• Plusieurs utilisateurs partagent les mêmes PDCH
• Le scheduler attribue quand il y a besoin → plus efficace

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📄 Page 182 — PCU + TBF

Ici on introduit les mécanismes de contrôle : (IR_Final_all_compressed-114-248.pdf)

3) PCU

• Situé au BSC (ou BTS)
• Communique avec SGSN
• Décide quel user reçoit quel timeslot UL/DL

4) Temporary Block Flow (TBF)

• Lorsqu’un user veut envoyer/recevoir : il demande un TBF
• Un TBF = flux logique temporaire uplink ou downlink
• Libéré à la fin du transfert

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📄 Page 183 — GPRS Control Channels + Dynamic balancing

On parle des nouveaux canaux pour gérer le data : (IR_Final_all_compressed-114-248.pdf)

5) Nouveaux canaux logiques

• PRACH : demande d’accès uplink
• PPCH : paging pour downlink data
• PBCCH : diffusion infos GPRS (optionnel)

6) Dynamic Resource Balancing

• L’opérateur choisit combien de timeslots en :
  • TCH (voix)
  • PDCH (data) ✅ Objectif : data sans casser la fiabilité voix

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📄 Page 184 — Schéma Voice timeslots vs Data timeslots

Cette page donne 3 exemples d’allocation des 8 timeslots GSM : (IR_Final_all_compressed-114-248.pdf)

1. Mixte voix + data (certains TCH, certains PDCH)
2. Tout voix (pas GPRS)
3. Tout data (GPRS dominant)

➡️ Ça montre que GPRS peut coexister avec la voix sur la même trame TDMA.

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✅ Protocole Stack (couches GPRS)

📄 Page 185 — Protocol Stack (IP → SNDCP → LLC)

Explication comment un paquet IP devient transmissible sur GSM : (IR_Final_all_compressed-114-248.pdf)

1) Application / IP Layer

• Data (web/email/MMS) créée en paquets IP

2) SNDCP

• Compression headers pour économiser bande passante
• Segmenter les gros paquets IP

3) LLC

• Chiffrement + fiabilité entre MS et SGSN
• Peut être ack ou unack

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📄 Page 186 — RLC/MAC + Physical Layer

Suite des couches : (IR_Final_all_compressed-114-248.pdf)

4) RLC/MAC

• Découpe en “radio blocks”
• Retransmissions via ARQ si erreur
• Planification des bursts sur PDCH

5) Physical layer

• Transmission sur l’air avec la modulation GSM (GMSK)
• Chaque burst correspond à la structure timeslot GSM

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✅ Coding Schemes (CS-1 → CS-4)

📄 Page 187 — Coding schemes concept (robustness vs throughput)

Explication du compromis : (IR_Final_all_compressed-114-248.pdf)

• Radio GSM = bruit + fading + interférences
• GPRS utilise “channel coding” :
  • plus de redondance = + fiable mais − débit
  • moins de redondance = + débit mais + erreurs

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📄 Page 188 — CS-1 (Most Robust)

Détails techniques : (IR_Final_all_compressed-114-248.pdf)

• Un bloc = 456 coded bits
• CS-1 :
  • user data = 181 bits
  • protection = 275 bits
• Débit ≈ 9 kbps/timeslot

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📄 Page 189 — CS-2 / CS-3 / CS-4

Comparaison des 4 coding schemes : (IR_Final_all_compressed-114-248.pdf)

• CS-2 :
  • user data 268 bits
  • débit ≈ 13 kbps/slot
• CS-3 :
  • user data 312 bits
  • débit ≈ 15 kbps/slot
• CS-4 :
  • user data 428 bits
  • protection minimale
  • débit ≈ 21 kbps/slot

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📄 Page 190 — Dynamic Adaptation

Le réseau choisit CS-1..CS-4 dynamiquement : (IR_Final_all_compressed-114-248.pdf)

• Il surveille :
  • C/I
  • BER
• Mauvaises conditions → CS-1 / CS-2
• Bonnes conditions → CS-3 / CS-4 ➡️ Explique pourquoi le débit GPRS varie selon position (cell edge vs proche BTS)

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✅ Multislot classes (plusieurs slots pour un user)

📄 Page 191 — Multislot Classes concept

Un seul timeslot = trop faible (9 à 21 kbps) (IR_Final_all_compressed-114-248.pdf)
Solution :

• Autoriser un user à utiliser plusieurs timeslots simultanément Une classe définit :
• max DL slots
• max UL slots
• max total

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📄 Page 192 — Classes examples + Network Reality

Exemples donnés : (IR_Final_all_compressed-114-248.pdf)

• Class 8 : 4 DL + 1 UL (max 5)
• Class 10 : 4 DL + 2 UL (max 5)
• Class 12 : 4 DL + 4 UL (max 5)

Réalité réseau :

• Même si téléphone supporte beaucoup, le réseau limite souvent
• PCU peut donner seulement 2 slots/user en cellule chargée
  ➡️ donc débit réel < débit théorique

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✅ Planning Dimensions en 2.5G (GPRS)

📄 Page 193 — Coverage + Capacity

Les critères de planification GPRS : (IR_Final_all_compressed-114-248.pdf)

Coverage

• GPRS = même couche radio que GSM → couverture de base similaire
• MAIS : couverture data “efficace” plus petite :
  • CS-3/CS-4 marche près BTS

Capacity

• Dépend du nombre de PDCH réservés (data) vs TCH (voix)
• Plus PDCH → + data capacity mais − voice capacity ➡️ équilibre très important

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📄 Page 194 — Latency & Scheduling + Device Density

Délais élevés typiques : (IR_Final_all_compressed-114-248.pdf)

• scheduling + retransmissions → 500 à 1000 ms
• trafic bursty → temps réponse variable
• ok pour email/browsing/MMS
• pas bon pour services temps réel (VoIP, gaming)

Device density :

• limitée par multislot class du mobile (ex Class 10)
• beaucoup d’utilisateurs pour peu de PDCH → débit moyen très faible

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✅ Exercice GPRS (dimensionnement débit)

📄 Page 195 — Exercise

Scénario : (IR_Final_all_compressed-114-248.pdf)

• GSM BTS avec 8 timeslots
• allocation : 3 PDCH pour data
• average coding : CS-2 ≈ 13 kbps
• handset : Class 10 (max 2 DL slots en pratique)
• 20 active users dans la cellule

Questions :

• débit max user si 2 slots ?
• capacité totale cell ?
• débit moyen si 20 users partagent ?
• impact sur latence ?
• trade-off voice/data ?

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📄 Page 196 — Exercise solution

Solution expliquée : (IR_Final_all_compressed-114-248.pdf)

• Débit par slot CS-2 ≈ 13 kbps
• max user avec 2 slots : 26 kbps
• capacité cell avec 3 PDCH : 3 × 13 = 39 kbps
• débit moyen par user : 39/20 ≈ 2 kbps ➡️ congestion énorme quand beaucoup d’utilisateurs

Latence :

• augmente fortement (scheduling + retransmissions)
• peut dépasser 1 seconde

Trade-off :

• • PDCH = meilleur débit data
• mais − TCH = moins de capacité voix ➡️ nécessite prévisions trafic et bon dimensionnement

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✅ Conclusion rapide (2.5G GPRS en 1 phrase)

📌 GPRS (2.5G) a transformé GSM en ajoutant un cœur paquet (SGSN/GGSN), des PDCH partagés, des mécanismes Always-on + PDP Context, mais avec des débits faibles et une latence élevée.

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Si tu veux, je peux aussi te faire : ✅ une fiche de révision 2.5G (ultra claire)
✅ ou un schéma résumé (architecture + attach + PDP context)
✅ ou encore 10 questions QCM uniquement sur GPRS avec correction.

Below is a detailed summary of the 2.75G section (EDGE) from your PDF, page by page, keeping all key points.

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Page 197 — Where EDGE fits (2G → 2.5G → 2.75G)

• A comparison table positions EDGE (2.75G) as an upgrade over GPRS (2.5G): same GSM base (FDMA+TDMA + packet switching), but adds 8-PSK to reach up to ~200 kbps per user.
• It also contrasts limitations and “why upgrade”:
  • GSM: very low speed (~9.6 kbps).
  • GPRS: higher but still limited throughput + high latency (~500–1000 ms).
  • EDGE: faster but more sensitive to signal quality and has smaller effective coverage. (IR_Final_all_compressed-114-248.pdf)

Page 198 — EDGE: main improvements

• EDGE provides ~3× higher data rates than GPRS.
• Key improvements listed:
  • Adaptive modulation (switch between GMSK and 8-PSK depending on signal quality).
  • Enables richer services (faster browsing/email, MMS, early streaming).
  • Positioned as a bridge between GPRS and 3G (UMTS). (IR_Final_all_compressed-114-248.pdf)

Pages 199–202 — EDGE architecture / structure (what changes, what stays)

Page 199–200 (MS + BTS):

• Mobile Station (MS) supports both GMSK (fallback) and 8-PSK (EDGE), and implements new MCS (Modulation and Coding Schemes) + multislot classes.
• BTS: only software upgrade needed at TRX to support EDGE modulation; no new spectrum/antennas; handles adaptive modulation switching. (IR_Final_all_compressed-114-248.pdf) (IR_Final_all_compressed-114-248.pdf)

Page 201 (BSC + PCU):

• BSC manages radio resources/handovers and coordinates timeslot allocation between voice (TCH) and data (PDCH).
• PCU does packet scheduling + QoS management and dynamically assigns PDCHs fairly among users. (IR_Final_all_compressed-114-248.pdf)

Page 202 (Core Network):

• Core network roles are unchanged from GSM/GPRS:
  • MSC handles voice/SMS.
  • SGSN manages mobility/session control for packet data.
  • GGSN connects to external IP networks.
  • APNs define gateways (internet vs corporate VPN). (IR_Final_all_compressed-114-248.pdf)

Pages 203–205 — Key features (rates, modulation, MCS)

Page 203 (higher data rates + new modulation):

• EDGE targets up to 59.2 kbps per timeslot, and with multislot classes, ~200 kbps practical per user.
• Introduces 8-PSK alongside GMSK:
  • 8-PSK carries 3 bits/symbol (higher spectral efficiency),
  • with adaptive fallback to GMSK in poor conditions. (IR_Final_all_compressed-114-248.pdf)

Page 204 (MCS concept):

• EDGE defines MCS-1 to MCS-9, balancing throughput vs robustness.
• The network selects MCS dynamically based on channel quality. (IR_Final_all_compressed-114-248.pdf)

Page 205 (full MCS table):

• Table lists modulation + per-timeslot data rates/throughput and notes:
  • MCS-1 to MCS-4 use GMSK (most robust → highest GMSK rate).
  • MCS-5 to MCS-9 use 8-PSK (higher rates, less coding at the top end).
  • MCS-9 is fastest (≈ 59.2 kbps/slot, ≈ 48 kbps throughput) but needs very good signal. (IR_Final_all_compressed-114-248.pdf)

Pages 206–207 — Compatibility, deployment, and services

Page 206 (backward compatibility + deployment simplicity):

• EDGE coexists with GSM and GPRS, keeping:
  • same spectrum, same timeslot structure,
  • auto switching for EDGE-capable devices depending on support/conditions,
  • and requires mainly software upgrades at BTS/TRX (cost-effective step toward 3G). (IR_Final_all_compressed-114-248.pdf)

Page 207 (services enabled):

• Examples of services EDGE enables:
  • faster web browsing + email,
  • MMS,
  • early low-quality audio/video streaming,
  • corporate VPN access via APNs. (IR_Final_all_compressed-114-248.pdf)

Page 208 — EDGE physical layer (why coverage shrinks)

• 8-PSK needs stronger signal than GMSK because it carries more bits per symbol (3 vs 1) → more sensitive to noise/interference.
• As a result:
  • effective EDGE coverage is smaller than GPRS,
  • at cell edge users often fall back to GMSK (lower throughput),
  • adaptive modulation keeps continuity (good signal → 8-PSK; poor → GMSK).
• Planning must ensure enough SNR, especially in dense urban and rural fringe areas, because signal quality decides which MCS is possible (therefore the data rate). (IR_Final_all_compressed-114-248.pdf)

Pages 209–211 — Planning dimensions in EDGE

Page 209 (coverage + capacity):

• Coverage:
  • smaller effective coverage than GPRS because 8-PSK needs higher quality,
  • requires careful site placement + overlap zones,
  • reminder: up to 59.2 kbps/slot (MCS-9).
• Capacity:
  • multislot classes allow ~200 kbps per user in good conditions,
  • more PDCHs increases data capacity but reduces voice TCHs → operator must balance voice vs data. (IR_Final_all_compressed-114-248.pdf)

Page 210 (latency + device density):

• Latency improves vs GPRS: ~300–500 ms typical, but still not suitable for real-time voice/video; acceptable for browsing/email/MMS/basic streaming.
• Device density:
  • multislot classes are mentioned (example given),
  • many users sharing PDCHs reduces average throughput → planning must consider user density per cell. (IR_Final_all_compressed-114-248.pdf)

Page 211 (QoS & scheduling):

• Adaptive modulation remains central (GMSK or 8-PSK depending on conditions).
• PCU schedules packet data dynamically.
• Corporate APNs may require stricter QoS guarantees. (IR_Final_all_compressed-114-248.pdf)

Pages 212–215 — EDGE exercise (scenario → questions → solution)

Page 212 (exercise scenario):

• Cell configuration: 1 carrier, 8 timeslots.
• Allocation: 4 PDCH (data) + 4 TCH (voice).
• Radio quality: inner cell users average MCS-6, edge users MCS-3.
• Per-slot assumptions: MCS-6 ≈ 48 kbps/slot, MCS-3 ≈ 22 kbps/slot.
• Users: 12 active EDGE users (8 inner + 4 edge).
• Multislot class: Class 12 (up to 4 DL slots when available). (IR_Final_all_compressed-114-248.pdf)

Page 213 (questions):

• Compute:
  1. total data capacity with 4 PDCH at MCS-6,
  2. max per-user throughput with 4 slots at MCS-6,
  3. average per-user throughput with 12 users sharing fairly (mixed MCS),
  4. quantify impact of signal quality drop (MCS-6 → MCS-3),
  5. voice–data tradeoff if PDCH increases to 5 (TCH drops to 3). (IR_Final_all_compressed-114-248.pdf)

Page 214 (solution part 1):

• Total cell capacity (4 PDCH, MCS-6): C = 4 × 48 = 192 kbps.
• Max per-user throughput (4 slots at MCS-6): Tuser,max = 4 × 48 = 192 kbps.
• Mixed MCS average capacity is computed (weighted by inner/edge proportions) and then divided by 12 users → ~13.14 kbps per user in the given mix example. (IR_Final_all_compressed-114-248.pdf)

Page 215 (solution part 2):

• Impact of signal quality: per-slot drop ΔR = 48 − 22 = 26 kbps, relative reduction ≈ 54.2%.
• Voice–data tradeoff example: with 5 PDCH, new data capacity becomes 5 × 48 = 240 kbps (while voice channels decrease because TCH count drops). (IR_Final_all_compressed-114-248.pdf)

Page 216 — EDGE limitations (transition to 3G)

• EDGE is presented as the last GSM upgrade, reaching ~200 kbps, but still limited by latency and coverage shrink with 8-PSK—this motivates the move to 3G. (IR_Final_all_compressed-114-248.pdf)

---

If you want, I can also turn this into a one-page revision sheet (definitions + architecture + MCS table explained + planning takeaways + exercise formulas).

Below is a detailed summary of the “3G section and onward” from your PDF (UMTS/WCDMA → WDM → FTTx + exercises), with a brief explanation of every page, and then a QCM + correction at the end.
Source: (IR_Final_all_compressed-114-248.pdf)

---

✅ 3G (UMTS / WCDMA) section — Page-by-page summary

---

Page 215 — EDGE limitations → why we move to 3G

This page concludes EDGE and explains why it was not enough:

• EDGE was the last GSM upgrade, reaching around ~200 kbps per user
• But it still suffered from:
  • Latency ~300–500 ms
  • Coverage shrink due to 8-PSK needing high signal quality
    So the transition to 3G UMTS/WCDMA becomes necessary. (IR_Final_all_compressed-114-248.pdf)

---

Page 216 — Why 3G was needed

The motivation for 3G:

• Early 2000s demand increased:
  • Video calls
  • Mobile TV
  • Rich browsing
• Needed Mbps-level data rates (beyond GSM + GPRS + EDGE)
• ITU’s IMT-2000 defined the official requirements for 3G
  (ITU = International Telecommunication Union, IMT = International Mobile Telecommunications). (IR_Final_all_compressed-114-248.pdf)

---

Page 217 — Introduction to UMTS/WCDMA

Key points of the first real mobile internet generation:

• 3G uses a new radio interface: WCDMA (Wideband CDMA)
• Uses 5 MHz channels (big jump compared to GSM 200 kHz)
• Supports broadband-like internet:
  • Data rate up to 2 Mbps
• Supports BOTH:
  • Circuit-switched voice
  • Packet-switched data
• UMTS/WCDMA is IMT-2000 compliant and marks mobile broadband start (IR_Final_all_compressed-114-248.pdf)

---

Page 218 — 3G Architecture overview

3G introduces a more layered and flexible structure:

• UE (User Equipment): 3G phone/modem
• UTRAN: the radio access network made of:
  • Node B + RNC
• Core Network:
  • MSC for voice
  • SGSN/GGSN for data (IR_Final_all_compressed-114-248.pdf)

---

Page 219 — UE and Node B

UE (User Equipment)

• Handles WCDMA signals and services
• Supports both voice (CS) + data (PS)
• Manages spreading codes and modulation
• Connects to Node B via Uu interface

Node B

• Equivalent of GSM BTS but for wideband CDMA
• Provides radio coverage for a cell/sector
• Performs:
  • spreading/despreading
  • power control
• Connected to RNC via Iub interface (IR_Final_all_compressed-114-248.pdf)

---

Page 220 — RNC (Radio Network Controller)

The “brain” of UTRAN (like BSC but more advanced):

• Controls multiple Node Bs
• Manages:
  • radio resources
  • handovers
  • admission control
  • load balancing
  • encryption
• Connected to core network through Iu interface (IR_Final_all_compressed-114-248.pdf)

---

Page 221 — Core network in 3G

3G core network mixes GSM legacy + packet services:

• MSC/VLR: circuit-switched voice
• SGSN: packet data mobility management
• GGSN: gateway to external IP networks
• HLR: subscriber database
• Supports both voice calls + internet access (IR_Final_all_compressed-114-248.pdf)

---

Page 222 — Interfaces in UMTS

UMTS defines modular interfaces:

• Uu: UE ↔ Node B
• Iub: Node B ↔ RNC
• Iu: RNC ↔ Core Network This modularity is one reason UMTS could evolve later toward LTE. (IR_Final_all_compressed-114-248.pdf)

---

Page 223 — Full 3G architecture diagram

A diagram shows the complete end-to-end system:

• UE connects to NodeB (UTRAN)
• RNC sits between NodeBs and core
• Core includes:
  • MSC/VLR (voice) + GMSC + PSTN
  • SGSN/GGSN to the Internet
  • HLR/AuC/EIR databases
    Also highlights the separation: Radio Access Network vs Core Network. (IR_Final_all_compressed-114-248.pdf)

---

Page 224 — 3G physical layer: Frequency bands

A table of UMTS frequency bands + planning effect:

• 850 MHz (Americas rural): larger cells, better penetration
• 900 MHz (refarmed GSM): extended coverage, good indoor
• 1700/2100 (North America): urban capacity
• 1900 MHz (Americas): smaller cells, dense urban reuse
• 2100 MHz (global main band): high capacity but smaller coverage radius (IR_Final_all_compressed-114-248.pdf)

---

Page 225 — 3G physical layer: radio properties

Key technical characteristics:

• Channel bandwidth: 5 MHz carriers
• Modulation:
  • baseline QPSK
  • enhanced 16-QAM in HSPA (adaptive modulation)
• Spreading codes: each user has a unique code (CDMA principle)
• Capacity nature: interference-limited (not slot-limited)
• Power control: critical to keep acceptable Eb/N0
  (HSPA = High Speed Packet Access) (IR_Final_all_compressed-114-248.pdf)

---

Page 226 — Planning dimensions in 3G (Coverage + Capacity)

Coverage

• 3G cells often smaller than GSM due to higher frequencies (1900/2100)
• Rural coverage improved by using 850/900 MHz

Capacity (major 3G concept)

• Unlike GSM, capacity is interference-limited
• More users ⇒ more interference ⇒ throughput decreases gradually
• This is called soft capacity
• Depends heavily on Eb/N0 + good power control (IR_Final_all_compressed-114-248.pdf)

---

Page 227 — Planning dimensions (Device density + QoS)

Device density

• More simultaneous users than 2G, but limited by interference
• Need load balancing

QoS

• 3G introduces differentiated services:
  • voice / video / data
• RNC manages:
  • admission control
  • prioritization
    Maintains critical services under load. (IR_Final_all_compressed-114-248.pdf)

---

Page 228 — 3G Exercise statement

Exercise gives parameters:

• W = 5 MHz
• Rd = 384 kbps
• Required Eb/N0 = 5 dB ≈ 3.16 (linear)
• System gain factor G ≈ 200 Task: compute maximum number of data users per cell using:

N = \frac{G}{(Eb/N0)\cdot (R/W)} $$ (IR_Final_all_compressed-114-248.pdf) --- ## **Page 229 — 3G Exercise solution** Step-by-step: 1) Rate fraction

R/W = 384000/5000000 = 0.0768

$$2) Denominator term$$

3.16 \times 0.0768 \approx 0.242

$$3) Users$$

N = 200 / 0.242 \approx 826.45 \approx 827

So theoretical max ≈ **827 data users per cell** (simplified model). (IR_Final_all_compressed-114-248.pdf) --- --- # ✅ WDM section (after 3G) — Page-by-page summary --- ## **Page 230 — What is WDM** WDM = Wavelength Division Multiplexing: - Multiple optical signals travel in the **same fiber** - Each uses a different **wavelength (color)** - Benefits: - increases fiber capacity without adding fiber - transports multiple services (Internet/voice/TV) simultaneously (IR_Final_all_compressed-114-248.pdf) --- ## **Page 231 — CWDM vs DWDM** Two types: ### CWDM (Coarse WDM) - Wide spacing ≈ **20 nm** - Fewer channels **(8–18)** - Metro/short distance networks ### DWDM (Dense WDM) - Narrow spacing ≈ **0.8 nm or less** - Many channels (40/80/160/320+) - Each wavelength can be 10G/40G/100G/200G/400G… - Used for **backbone + long distance** (IR_Final_all_compressed-114-248.pdf) --- ## **Page 232 — Dimensioning WDM: number of wavelengths** Steps: - Decide number of wavelengths based on traffic - Example: - 40 wavelengths × 10Gbps = **400Gbps capacity** - Each wavelength carries a given bit rate (2.5/10/40/100Gbps etc.) - Higher bit rates need better components + tighter spacing (IR_Final_all_compressed-114-248.pdf) --- ## **Page 233 — Dimensioning WDM: optical budget + topology** - Compute optical losses: - attenuation, connectors, splices - Must ensure received power > sensitivity - Add margins for aging/upgrades - Choose topology: - ring / mesh / point-to-point - Dimensioning depends on number of nodes and amplifiers. (IR_Final_all_compressed-114-248.pdf) --- --- # ✅ FTTx section — Page-by-page summary --- ## **Page 234 — Intro to FTTx** FTTx = Fiber to the x (home/building/curb/office…): - High bandwidth compared to copper - Supports HD video, cloud apps, online gaming - Future-proof - Closer fiber to user = higher speed + lower latency + better reliability (IR_Final_all_compressed-114-248.pdf) --- ## **Page 235 — Types of FTTx** Defines: - **FTTH**: fiber to residence - **FTTB**: fiber to building then internal distribution - **FTTC**: fiber to cabinet then copper to home - **FTTO**: fiber to business - Also mentions **FTTN**: fiber to nodes (antenna). (IR_Final_all_compressed-114-248.pdf) --- ## **Page 236 — (FTTx diagram page)** This page is mainly visual (architecture illustration of fiber reaching closer to users). (IR_Final_all_compressed-114-248.pdf) --- ## **Page 237 — Dimensioning FTTx: bandwidth + subscribers** First steps of sizing: - Define target speed per user (100 Mbps / 1Gbps…) - Estimate number of subscribers - Example: 1000 homes in a neighborhood (IR_Final_all_compressed-114-248.pdf) --- ## **Page 238 — Split ratio + feeder capacity** Passive Optical Networks (PON): - Uses splitters (no powered equipment) - Split ratios: **1:16, 1:32, 1:64** - Example: 1:32 means 1 feeder fiber serves 32 homes Feeder capacity calculation: - per-user bandwidth × users per splitter - Example: 100 Mbps × 32 = **3.2 Gbps** (IR_Final_all_compressed-114-248.pdf) --- ## **Page 239 — Distance limit** Distance between: - **OLT** (central office) and **ONT** (user terminal) Usually max ≈ **20 km for GPON** Dimensioning must respect distance to avoid loss. (IR_Final_all_compressed-114-248.pdf) --- ## **Page 240 — FTTx Network (diagram)** Mostly a network diagram showing OLT → splitters → ONT distribution. (IR_Final_all_compressed-114-248.pdf) --- ## **Page 241 — Planning an FTTx network** Architecture options: - **PON**: shared fiber using splitters - **Point-to-Point**: dedicated fiber per user (costly but best performance) Equipment placement: - OLT: central office - Splitters: cabinets/distribution points - ONT: user side conversion optical → data (IR_Final_all_compressed-114-248.pdf) --- ## **Page 242 — Reliability + scalability** Key planning points: - Distance limit again (≈20 km GPON) - Splitters add loss ⇒ check optical budget - Reliability: - backup fibers / redundant paths - maintenance access - Scalability: - plan growth (start 1:32, later 1:64) (IR_Final_all_compressed-114-248.pdf) --- ## **Page 243 — Final exercise scenario (WDM + FTTx)** Scenario: - **DWDM ring** with: - 40 wavelengths - each 10Gbps - 4 nodes - total fiber 120 km - GPON neighborhood: - 960 homes - target 100 Mbps per user - split 1:32 - OLT–ONT must be ≤ 20 km (IR_Final_all_compressed-114-248.pdf) --- ## **Page 244 — Exercise tasks** Part A (WDM): - A1 total backbone capacity - A2 amplifiers needed if max span = 80 km Part B (FTTx): - B1 ports needed for 960 homes with split 1:32 - B2 feeder capacity per splitter - B3 check if 18 km meets distance limit (IR_Final_all_compressed-114-248.pdf) --- ## **Page 245 — Exercise solution Part A (WDM)** A1:

C = 40 \times 10Gbps = 400Gbps

$$A2:$$

Nspans = 120/80 = 1.5 \Rightarrow 2\text{ spans}

So place **2 amplifiers** to keep each span ≤ 80 km (IR_Final_all_compressed-114-248.pdf) --- ## **Page 246 — Exercise solution Part B (FTTx)** B1 OLT ports:

960/32 = 30

$$B2 feeder capacity:$$

100Mbps \times 32 = 3.2Gbps

$$B3 distance check:$$

18km \le 20km \Rightarrow \text{OK}

--- ## **Page 247 — Acronyms page** Quick glossary of extra acronyms: - DPI, TDF, SGW, PGW, UPF, eNB, gNB… (IR_Final_all_compressed-114-248.pdf) --- --- # ✅ QCM (3G section and onward) + Correction ### **Q1.** The main reason EDGE pushed the need for 3G was: A) EDGE had no encryption B) EDGE had low bandwidth per user and couldn’t support multimedia well C) EDGE could not carry voice calls D) EDGE replaced Internet completely ### **Q2.** According to the course, 3G requirements were defined by: A) IEEE 802.11 B) ITU IMT-2000 C) ETSI GSM Phase 1 D) 3GPP Release 18 ### **Q3.** UMTS uses which access method? A) FDMA B) TDMA C) WCDMA D) OFDMA ### **Q4.** UMTS channel bandwidth is typically: A) 200 kHz B) 1.25 MHz C) 5 MHz D) 20 MHz ### **Q5.** The maximum data rate mentioned for UMTS is about: A) 200 kbps B) 2 Mbps C) 10 Mbps D) 100 Mbps ### **Q6.** In 3G architecture, UTRAN is composed of: A) BTS + BSC B) Node B + RNC C) eNB + EPC D) gNB + 5GC ### **Q7.** The interface between UE and Node B is: A) Iu B) Iub C) Uu D) S1 ### **Q8.** Node B connects to RNC using: A) Uu B) Iub C) Iu D) X2 ### **Q9.** RNC connects to the Core Network using: A) Iu B) Iub C) Uu D) S5 ### **Q10.** The 3G core element managing circuit-switched voice is: A) SGSN B) GGSN C) MSC/VLR D) RNC ### **Q11.** In UMTS, each user is separated mainly using: A) Time slots B) Spreading codes C) Fixed FDMA carriers D) Subcarriers ### **Q12.** 3G capacity is described as: A) Slot-limited capacity B) Interference-limited capacity (soft capacity) C) Fully unlimited capacity D) Only coverage-limited ### **Q13.** Why is power control critical in WCDMA? A) It increases SIM security B) It balances signals and maintains required Eb/N0 C) It replaces modulation D) It removes routing ### **Q14.** The baseline modulation in UMTS is: A) FM B) GMSK C) QPSK D) 64-QAM ### **Q15.** In the 3G exercise, the computed maximum number of users was about: A) 87 B) 200 C) 827 D) 5000 --- ## ✅ Correction (Solutions) 1:B 2:B 3:C 4:C 5:B 6:B 7:C 8:B 9:A 10:C 11:B 12:B 13:B 14:C 15:C --- If you want, I can also make you a **bigger exam-style QCM (30–40 questions)** only on **3G + WDM + FTTx**, with calculations included (Eb/N0, capacity WDM, split ratio, feeder sizing, etc.).

Below is a clean, exam-oriented, but still detailed summary of the 3G section and onward from your PDF, excluding content that is clearly not exam-relevant (pure illustrations, repeated diagrams, acronym-only slides, or obvious recap slides).
At the end, you’ll find a QCM (MCQ) with solutions focused on 3G + WDM + FTTx.

Source: IR_Final_all_compressed-114-248.pdf (IR_Final_all_compressed-114-248.pdf)

---

✅ 3G (UMTS / WCDMA) — Exam-relevant summary

---

1. Why 3G was needed (EDGE limitations → motivation)

• EDGE (2.75G) was the last GSM upgrade
  • Peak user rate ≈ 200 kbps
  • Latency ≈ 300–500 ms
  • Coverage shrinks with 8-PSK
• By early 2000s, users demanded:
  • Video calls
  • Mobile TV
  • Rich web browsing
• GSM upgrades reached their limit → new generation required
• ITU IMT-2000 defined global 3G requirements
  (ITU = International Telecommunication Union)

Exam takeaway:
👉 3G was required to deliver Mbps-level data, not achievable with GSM/EDGE.

---

2. Introduction to UMTS / WCDMA

• First true 3G system
• New radio interface: WCDMA (Wideband CDMA)
• Channel bandwidth = 5 MHz (vs 200 kHz in GSM)
• Supports:
  • Circuit-switched voice
  • Packet-switched data
• Peak data rate ≈ 2 Mbps
• First system compliant with IMT-2000
• Marks the beginning of mobile broadband

Exam takeaway:
👉 3G = Wideband CDMA + 5 MHz + voice & data

---

3. 3G Architecture (UMTS structure)

Main blocks

• UE (User Equipment)
  3G phone or modem
• UTRAN (Radio Access Network)
  • Node B
  • RNC
• Core Network
  • MSC/VLR → voice
  • SGSN/GGSN → data
  • HLR → subscriber database

---

UE (User Equipment)

• Handles WCDMA signals
• Supports CS voice + PS data
• Uses spreading codes
• Connects to Node B via Uu interface

---

Node B

• 3G equivalent of GSM BTS
• Provides radio coverage
• Performs:
  • Spreading / despreading
  • Fast power control
• Connects to RNC via Iub interface

---

RNC (Radio Network Controller)

• “Brain” of UTRAN
• Controls multiple Node Bs
• Functions:
  • Radio resource management
  • Handover control
  • Admission control
  • Load balancing
  • Encryption
• Connects to core via Iu interface

---

Core Network (3G)

• MSC/VLR: circuit-switched voice
• SGSN: packet mobility management
• GGSN: gateway to external IP networks
• HLR: permanent subscriber data

Exam takeaway:
👉 GSM core reused, but new radio access (UTRAN) introduced.

---

4. UMTS Interfaces (important for exams)

• Uu: UE ↔ Node B
• Iub: Node B ↔ RNC
• Iu: RNC ↔ Core Network

👉 Modular design → easier evolution to LTE

---

5. 3G Physical Layer (exam-critical)

Frequency bands (planning relevance)

• 850 / 900 MHz:
  • Large cells
  • Better indoor penetration
  • Rural / suburban
• 1900 / 2100 MHz:
  • Smaller cells
  • Higher capacity
  • Urban deployments

---

Radio characteristics

• Channel bandwidth: 5 MHz
• Modulation:
  • Baseline: QPSK
  • Enhanced (HSPA): 16-QAM
• Multiple access: CDMA (users separated by codes)
• Capacity nature: Interference-limited
• Power control: critical to maintain Eb/N0

Exam takeaway:
👉 3G capacity is soft capacity, not slot-limited.

---

6. Planning Dimensions in 3G (very exam-relevant)

Coverage

• Higher frequencies → smaller cells
• Lower bands used to extend coverage

Capacity

• Interference-limited
• More users ⇒ more interference ⇒ lower throughput
• Depends on Eb/N0 and power control

Device Density

• More users than 2G
• Limited by interference → load balancing required

QoS

• Differentiated services (voice, video, data)
• Managed by RNC (admission + prioritization)

---

7. 3G Capacity Exercise (concept, not numbers)

• Uses simplified WCDMA formula:

$$N = \frac{G}{(E_b/N_0)\cdot (R/W)}$$

• Shows that hundreds of users per cell are theoretically possible
• Demonstrates interference-limited nature of 3G

Exam takeaway:
👉 Know formula meaning, not heavy math.

---

✅ WDM (Wavelength Division Multiplexing) — Exam-relevant summary

---

1. What is WDM

• Multiple optical signals over one fiber
• Each uses a different wavelength
• Increases capacity without new fiber

---

2. CWDM vs DWDM

CWDM

• Spacing ≈ 20 nm
• 8–18 channels
• Metro / short distance

DWDM

• Spacing ≈ 0.8 nm
• 40 / 80 / 160+ channels
• Each wavelength can carry 10G–400G
• Backbone / long distance

---

3. WDM Dimensioning (exam-relevant)

• Total capacity =
  Number of wavelengths × bit rate per wavelength
• Must check:
  • Optical losses
  • Receiver sensitivity
  • Amplifier spacing
• Topologies:
  • Ring
  • Mesh
  • Point-to-point

---

✅ FTTx — Exam-relevant summary

---

1. What is FTTx

• Fiber deployed closer to user
• Very high bandwidth
• Low latency
• Future-proof

---

2. FTTx Types

• FTTH: Fiber to Home
• FTTB: Fiber to Building
• FTTC: Fiber to Curb
• FTTO: Fiber to Office
• FTTN: Fiber to Node (antennas)

---

3. FTTx Dimensioning (key exam points)

Bandwidth

• Define target per user (e.g. 100 Mbps)

PON & Split ratio

• Passive Optical Network
• Typical splits: 1:16, 1:32, 1:64
• Feeder capacity:

$$\text{Feeder} = \text{User rate} \times \text{users per splitter}$$

---

Distance constraint

• GPON max distance ≈ 20 km (OLT–ONT)

Equipment

• OLT: central office
• Splitter: passive, divides signal
• ONT: user side

---

✅ QCM — 3G + WDM + FTTx

Q1. The main reason for introducing 3G was:

A) GSM lacked encryption
B) EDGE could not support MMS
C) Need for Mbps-level mobile data
D) GSM spectrum was unused

Q2. UMTS radio access is based on:

A) TDMA
B) FDMA
C) WCDMA
D) OFDMA

Q3. The standard UMTS channel bandwidth is:

A) 200 kHz
B) 1.25 MHz
C) 5 MHz
D) 20 MHz

Q4. Which element controls multiple Node Bs?

A) MSC
B) SGSN
C) RNC
D) GGSN

Q5. The interface between UE and Node B is:

A) Iu
B) Iub
C) Uu
D) X2

Q6. 3G capacity is mainly limited by:

A) Number of time slots
B) Fixed frequency reuse
C) Interference level
D) SIM card speed

Q7. In WDM, DWDM differs from CWDM mainly by:

A) Using copper cables
B) Larger wavelength spacing
C) Much denser wavelength spacing
D) Being wireless

Q8. Total WDM capacity equals:

A) Fiber length × attenuation
B) Wavelength spacing × power
C) Number of wavelengths × bit rate per wavelength
D) Number of nodes × amplifiers

Q9. Which FTTx architecture brings fiber directly to homes?

A) FTTC
B) FTTB
C) FTTH
D) FTTN

Q10. Typical GPON maximum OLT–ONT distance is about:

A) 5 km
B) 10 km
C) 20 km
D) 80 km

---

✅ QCM Solutions

1. C
2. C
3. C
4. C
5. C
6. C
7. C
8. C
9. C
10. C

---

If you want, I can next:

• Compress this into a 2–3 page exam revision sheet
• Build a full exam (theory + exercises + QCM)
• Or highlight “questions that always fall in exams” for 3G / WDM / FTTx

Here’s an exam-ready “memory refresh” summary for the whole PDF (Chapter 2: Mobile Generations + WDM/FTTx). I’m keeping all the important points you’re likely to be tested on, but in a compact revision style.

---

Big picture (what changes from 1G → 5G)

• Core evolution: circuit-switched → packet-switched → all-IP → service-based (5G).
• Access type: FDMA (1G) → TDMA/CDMA (2G) → CDMA (3G) → OFDMA (4G) → flexible numerology (5G).
• Key services: analog voice → digital voice + SMS → mobile data → broadband IP → eMBB/URLLC/mMTC. (IR_Final_all_compressed-114-248.pdf)

---

The 4 planning dimensions (always testable)

• Coverage: where users receive acceptable service → drives site count/placement.
• Capacity: throughput a cell/sector must support → drives bandwidth & spectrum choices.
• Latency: end-to-end delay constraints → affects scheduling/transport.
• Device density: active devices per km² → affects signaling, RAN load, and small-cell needs. (IR_Final_all_compressed-114-248.pdf)

Cell types link to planning: macro/micro/pico relate to coverage + reuse decisions. (IR_Final_all_compressed-114-248.pdf)
(Examples in the course: rural = macrocells, urban = microcells, indoor = pico/micro concepts appear through indoor solutions.) (IR_Final_all_compressed-114-248.pdf) (IR_Final_all_compressed-114-248.pdf)

---

1G — Analog voice (FDMA planning)

What 1G is

• First mobile systems (1980s), analog voice only, no SMS/encryption/data. Standards: AMPS, variants NMT/TACS. (IR_Final_all_compressed-114-248.pdf)

Architecture (know the blocks)

• MS (FM analog handset)
• BTS (assigns fixed frequency channel per user with FDMA)
• MSC (connects BTSs to PSTN; call setup/routing/billing)
• PSTN (landline network) (IR_Final_all_compressed-114-248.pdf)
• No control channels / no encryption / analog circuit switching. (IR_Final_all_compressed-114-248.pdf)

Radio facts (often asked)

• FDMA + FM, typically FDD (uplink/downlink separated), fixed channel allocation + guard bands. (IR_Final_all_compressed-114-248.pdf)
• Channel bandwidth ~25–30 kHz (AMPS style). (IR_Final_all_compressed-114-248.pdf)
• Control channels exist in AMPS context: FOCC / RECC for signaling (system/registration/call setup control). (IR_Final_all_compressed-114-248.pdf)

Core planning formulas (must remember)

• Reuse distance: $D = R\sqrt{3N}$ where $R$=cell radius, $N$=cluster size.
• Capacity per cell (FDMA idea): $C = \dfrac{\text{available channels}}{N}$.
• 1G planning priority: coverage first, capacity by reuse/channel count. (IR_Final_all_compressed-114-248.pdf)

---

2G — Digital voice, SMS, GSM breakthrough

What 2G adds (key “upgrade list”)

• Shift analog → digital: voice compression, SMS, better capacity/quality. (IR_Final_all_compressed-114-248.pdf)
• Introduces SIM (identity), authentication & encryption, mobility management (location update/paging), and international roaming (GSM). (IR_Final_all_compressed-114-248.pdf)
• 2G can be GSM (TDMA/FDMA) or IS-95 (CDMA). (IR_Final_all_compressed-114-248.pdf)

GSM architecture (know roles)

• Layered/modular design separating radio access + core + databases. (IR_Final_all_compressed-114-248.pdf)
• Core + databases include: MSC/VLR, HLR, AuC, EIR, GMSC. (You’re expected to know what they do: switching + visitor data, home subscriber DB, auth center, equipment ID/blacklist, gateway to PSTN.) (IR_Final_all_compressed-114-248.pdf)

GSM physical layer essentials

• Carrier bandwidth = 200 kHz, modulation GMSK, and each carrier is split into 8 timeslots (TDMA). (IR_Final_all_compressed-114-248.pdf)
• TDMA frame duration shown: 4.615 ms. (IR_Final_all_compressed-114-248.pdf)

GSM logical channels (very exam-friendly)

• RACH: random access request (uplink)
• PCH: paging (downlink)
• AGCH: assigns resources (downlink)
• SDCCH: signaling for call setup/authentication
• TCH: carries voice/data traffic (IR_Final_all_compressed-114-248.pdf)

Call setup sequence (typical)

1. MS sends request on RACH
2. BTS/BSC grants channel via AGCH
3. Signaling on SDCCH (authentication/call setup)
4. Assign TCH for the call (IR_Final_all_compressed-114-248.pdf)

2G traffic engineering (Erlang + GoS)

• Typical busy-hour traffic per user: 0.02–0.03 Erlangs (example uses 0.025). (IR_Final_all_compressed-114-248.pdf)
• GoS is blocking probability (target often 2%). (IR_Final_all_compressed-114-248.pdf)
• Erlang-B formula is used to relate offered traffic $A$, channels $N$, and blocking $B(A,N)$. (IR_Final_all_compressed-114-248.pdf)

Exercise model to remember (the one in the slides):

• Population 200k, 40% penetration → 80,000 subs
• Busy hour traffic = 80,000 × 0.025 = 2000 Erlangs
• Heuristic at 2% GoS gives ≈ 3200 TCH
• Convert to carriers: 3200 / 8 = 400 carriers
• Per BTS capacity (3 sectors, 10 carriers/sector, 8 TS): 3×10×8 = 240 TS; after control reservation → 237 TCH effective
• BTS count ≈ 3200 / 237 ≈ 14 BTS (IR_Final_all_compressed-114-248.pdf)

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2.5G — GPRS (packet data overlay on GSM)

Why GPRS (what problem it solves)

• GSM 2G is circuit-switched (voice/SMS). Late 1990s demand for email/WAP/MMS and “always-on” data → add packet overlay without rebuilding GSM. (IR_Final_all_compressed-114-248.pdf)
• GPRS = packet-switched extension that carries IP packets alongside voice/SMS; “bridge” between GSM and UMTS. (IR_Final_all_compressed-114-248.pdf)

New network elements (must know)

• SGSN: mobility/authentication + routes packets between mobiles and radio network
• GGSN: gateway to external IP networks; assigns IP via PDP context; acts as gateway router
• PCU: manages packet data channels; usually in BSC (sometimes BTS) (IR_Final_all_compressed-114-248.pdf)

Key procedures (Attach + PDP context)

1. GPRS Attach: MS → SGSN; SGSN checks HLR subscription/APN/QoS; stores Routing Area (IR_Final_all_compressed-114-248.pdf)
2. PDP Context activation: MS requests (APN + QoS) → SGSN → GGSN; GGSN assigns IP + routing; confirmation back (IR_Final_all_compressed-114-248.pdf)
3. Always-On session: data any time; multiple PDP contexts possible (internet + VPN) (IR_Final_all_compressed-114-248.pdf)
4. QoS & billing: QoS params (delay/reliability/precedence/throughput); billing shifts to MB, APN separation (public vs corporate) (IR_Final_all_compressed-114-248.pdf)

Radio resource idea (GSM voice vs GPRS data)

• Voice: timeslot reserved continuously for one user.
• GPRS: timeslots redefined as PDCH, shared via statistical multiplexing (scheduler gives bursts only when needed). (IR_Final_all_compressed-114-248.pdf)

GPRS coding schemes (rates per slot)

• CS-1 to CS-4 adapt to radio quality (C/I, BER).
• Per timeslot data rates shown: CS-1 ≈ 9 kbps, CS-2 ≈ 13 kbps, CS-3 ≈ 15 kbps, CS-4 ≈ 21 kbps. (IR_Final_all_compressed-114-248.pdf)

Latency + limits

• Typical GPRS latency ~500–1000 ms (still slow for real-time apps). (IR_Final_all_compressed-114-248.pdf)

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2.75G — EDGE (enhanced data rates)

What EDGE changes

• Keeps GSM timeslot structure + spectrum, but increases rate using 8-PSK (and falls back to GMSK). (IR_Final_all_compressed-114-248.pdf)
• Deployment: mostly software upgrade at BTS/TRX, no new spectrum/antennas. (IR_Final_all_compressed-114-248.pdf)
• Services: faster browsing/email, MMS, early low-quality streaming, VPN via APNs. (IR_Final_all_compressed-114-248.pdf)

Physical layer + planning implications (very testable)

• 8-PSK carries 3 bits/symbol vs 1 (GMSK) → higher sensitivity to noise/interference.
• Therefore EDGE coverage is smaller than GPRS, and at cell edge users fall back to GMSK. (IR_Final_all_compressed-114-248.pdf)
• Planning must ensure enough SNR; signal quality determines which MCS is usable → determines user rate. (IR_Final_all_compressed-114-248.pdf)
• Per timeslot peak: 59.2 kbps (MCS-9); with multislot classes users can reach ~200 kbps; PDCH vs TCH is the voice-data tradeoff. (IR_Final_all_compressed-114-248.pdf)

EDGE limitations → why 3G

• EDGE: ~200 kbps, ~300–500 ms latency, coverage shrinks with 8-PSK. (IR_Final_all_compressed-114-248.pdf)

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3G — UMTS / WCDMA (first “true” mobile internet)

Why 3G was needed

• Demand for video calls, mobile TV, rich browsing → Mbps-level rates; GSM upgrades hit limits.
• 3G requirements defined by ITU IMT-2000. (IR_Final_all_compressed-114-248.pdf)

UMTS/WCDMA basics

• Access: WCDMA, 5 MHz channels (vs 200 kHz GSM)
• Data up to 2 Mbps
• Supports both circuit voice + packet data
• First IMT-2000 compliant mobile broadband. (IR_Final_all_compressed-114-248.pdf)

Architecture (UE / UTRAN / Core)

• UE: handles WCDMA; uses spreading codes/modulation; UE ↔ NodeB via Uu (IR_Final_all_compressed-114-248.pdf)
• UTRAN = Node B + RNC; NodeB ↔ RNC via Iub (IR_Final_all_compressed-114-248.pdf)
• RNC: “brain” (like BSC but more advanced): radio resources + handovers + admission + load balancing + encryption; RNC ↔ core via Iu (IR_Final_all_compressed-114-248.pdf)
• Core: MSC/VLR (voice), SGSN (packet mobility), GGSN (gateway), HLR (subscriber DB). (IR_Final_all_compressed-114-248.pdf)
• Interfaces to memorize: Uu, Iub, Iu. (IR_Final_all_compressed-114-248.pdf)

Physical layer & “soft capacity”

• 5 MHz carriers, modulation QPSK (and 16-QAM in HSPA), users separated by spreading codes. (IR_Final_all_compressed-114-248.pdf)
• Capacity is interference-limited (not slot-limited): more users → more interference → gradual throughput drop. (IR_Final_all_compressed-114-248.pdf)
• Power control is critical to maintain required Eb/N0. (IR_Final_all_compressed-114-248.pdf)
• Planning: high bands (1900/2100) → smaller cells; low bands (850/900) → larger cells + better indoor. Soft capacity concept explicitly stated. (IR_Final_all_compressed-114-248.pdf)

3G exercise result (know the method + final number)

Using simplified relation $N=\dfrac{G}{(Eb/N0)\cdot (R/W)}$: the provided scenario yields ≈ 827 users. (IR_Final_all_compressed-114-248.pdf)

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WDM — Wavelength Division Multiplexing

Definition + why it matters

• Multiple optical signals in one fiber, each on a different wavelength (“color”), increasing capacity without new fiber; can carry Internet/voice/TV together. (IR_Final_all_compressed-114-248.pdf)

CWDM vs DWDM (numbers are testable)

• CWDM: ~20 nm spacing, 8–18 channels, metro/short distance.
• DWDM: ~0.8 nm or less, 40/80/160/320+ channels; backbone/long distance; each channel can be 10G/40G/100G/… (IR_Final_all_compressed-114-248.pdf)

Dimensioning steps

• Decide # wavelengths based on demand; example: 40 × 10 Gbps = 400 Gbps. (IR_Final_all_compressed-114-248.pdf)
• Do optical budget: attenuation/connectors/splices; ensure received power above sensitivity; add margins; pick topology (ring/mesh/ptp) + amplifiers. (IR_Final_all_compressed-114-248.pdf)

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FTTx — Fiber to the x (fixed access)

What it is + types

• Bringing fiber closer to users gives high bandwidth, low latency, future-proof access. (IR_Final_all_compressed-114-248.pdf)
• Types: FTTH, FTTB, FTTC, FTTO, FTTN (and fiber closer → higher speed). (IR_Final_all_compressed-114-248.pdf)

Dimensioning (the “must know” formulas/limits)

• PON split ratios: 1:16 / 1:32 / 1:64. (IR_Final_all_compressed-114-248.pdf)
• Feeder capacity per splitter: (per-user rate) × (users per split) e.g., 100 Mbps × 32 = 3.2 Gbps. (IR_Final_all_compressed-114-248.pdf)
• Distance constraint (GPON): OLT–ONT typically ≤ 20 km. (IR_Final_all_compressed-114-248.pdf)
• Reliability/scalability: optical budget, splitter losses, plan upgrades. (IR_Final_all_compressed-114-248.pdf)

Final combined exercise (what to remember)

• WDM ring example capacity: 40 wavelengths × 10 Gbps = 400 Gbps. (IR_Final_all_compressed-114-248.pdf)
• FTTx example: 960 homes, split 1:32 → 960/32 = 30 OLT ports; feeder 3.2 Gbps; 18 km ≤ 20 km OK. (IR_Final_all_compressed-114-248.pdf)

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Ultra-short “things to memorize” checklist (last-minute)

• 1G: analog voice, FDMA, FM, 25–30 kHz channels, reuse: $D=R\sqrt{3N}$, no encryption/SMS/data. (IR_Final_all_compressed-114-248.pdf) (IR_Final_all_compressed-114-248.pdf)
• 2G GSM: 200 kHz carrier, 8 TS, GMSK, channels RACH/PCH/AGCH/SDCCH/TCH, call setup steps, Erlang/GoS planning. (IR_Final_all_compressed-114-248.pdf) (IR_Final_all_compressed-114-248.pdf) (IR_Final_all_compressed-114-248.pdf) (IR_Final_all_compressed-114-248.pdf)
• GPRS (2.5G): SGSN/GGSN/PCU, attach + PDP context + always-on, PDCH shared, CS-1..CS-4 (9/13/15/21 kbps), latency 500–1000 ms. (IR_Final_all_compressed-114-248.pdf) (IR_Final_all_compressed-114-248.pdf) (IR_Final_all_compressed-114-248.pdf) (IR_Final_all_compressed-114-248.pdf)
• EDGE (2.75G): 8-PSK (3 bits/symbol) + fallback GMSK, smaller coverage, up to 59.2 kbps/slot, ~200 kbps user, voice/data PDCH tradeoff. (IR_Final_all_compressed-114-248.pdf)
• 3G UMTS/WCDMA: 5 MHz, up to 2 Mbps, UE/NodeB/RNC, Uu/Iub/Iu, interference-limited “soft capacity”, power control/Eb/N0, example capacity result ≈ 827. (IR_Final_all_compressed-114-248.pdf) (IR_Final_all_compressed-114-248.pdf) (IR_Final_all_compressed-114-248.pdf) (IR_Final_all_compressed-114-248.pdf)
• WDM: CWDM 20 nm (8–18 ch) vs DWDM 0.8 nm (40+ ch), capacity = wavelengths × rate, optical budget. (IR_Final_all_compressed-114-248.pdf)
• FTTx: FTTH/FTTB/FTTC/FTTO/FTTN, PON splits 1:16/32/64, feeder = user×split, GPON ~20 km. (IR_Final_all_compressed-114-248.pdf) (IR_Final_all_compressed-114-248.pdf)

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If you want, I can also turn this into a one-page “formula + numbers” sheet (just the equations, typical values, and architecture blocks) so you can revise in 2 minutes before the exam.