1. Network Architecture How does it all work?
Charts and acronym explanations sourced from:

2. Cisco 3-Teired Heirarchy
Similar concept to OSI model
Each tier addresses different tasks; optimizes traffic
Layers:
Core
Distribution
Access

3. Core layer Equipment example : ORC routers
Network backbone; connects MSOs
100GB connection between bigger MSOs
10GB connection between most MSOs
Optimized to pass traffic as fast and reliably as possible
Nodes connected via fast WAN circuits
MPLS routing

4. Distribution layer Equipment example : DRC routers
Ensures packets are properly routed between VLANs and subnets
Provides aggregation and redundancy
Functions as the “middle man” between the backbone and “front door”

5. Access layer Equipment example: MAD routers Network’s “front door”
Provides network access control; prevents unauthorized access
Passes traffic between cell sites/UE and distribution routers

6. Important concepts for call flows
Circuit-switched
Mostly used for voice calling
Dedicated logical link from point A to Z
Resources allocated for duration of call
Packet-switched
Mostly used for data connections
Packets over IP
Control-plane (c-plane)
Signalling between nodes
Behind-the-scenes
Handles data about the user’s connection
User-plane (u-plane)
Communication between peers, i.e. call between 2 phones, data connection between phone and internet, etc.

7. 2G/3G network architecture
BSC – Base Station Controller; manages and organizes 2G cells
RNC – Radio Network Controller; manages and organizes 3G cells
MGW – Media Gateway; interlink data streams on different protocols & technologies
MSS – Mobile Switching Server; 2G CS call control

8. 2G/3G network architecture
HLR – Home Location Register; contains info on subscribers located in its jurisdiction
VLR – Visitor Location Register; manages information on temporary (roaming) subscribers
Both authenticate users and retrieve profile info

9. 2G/3G network architecture
SGSN – Support GPRS Service Node; mobility and session management during calls, route to HLR, support SMS, setup data plane to GGSN, handover to 4G
GGSN – Gateway GPRS Service Node; session management, IP allocation, QoS enforcement, route to internet

10. Get info for this subscriber
Sample 2G/3G call flow
Reference : TS TS TS 1
Attach request..
Herewith the info 3
HLR
Gn DNS MS
BTS / Nodeb
Abis / Iub
I am attached to the network and want to browse, by activating PDP context 5
BSC
RNC
Get info for this subscriber
Packet Data Network
e..g Internet 2
Gb IuPS
SGSN Gn
GGSN
Attach accepted.. 4
Internet DNS

11. Create PDP Context accepted
Sample 2G/3G call flow
Reference : TS TS TS
Herewith the IP address of GGSN 7
HLR
Gn DNS MS
BTS / Nodeb
Abis - Iub
I am attached to the network and want to browse , by activating PDP context 5
BSC
RNC
Gb -IuPS
Packet Data Network
e..g Internet
SGSN Gn
GGSN Gi 9
Internet DNS 11 6 8
Create PDP Context accepted
PDP context activation accepted, now browse to
PDP context activation received from MS,
What is the IP address of the GGSN that serving this APN ? ?
Create PDP Context Request 10
Create PDP context accepted, send this info to MS

12. PDP context activation accepted, now browse to
Sample 2G/3G call flow
Reference : TS TS TS
HLR
Gn DNS MS
BTS / Nodeb
Abis - Iub 12
Gb -IuPS
Packet Data Network
e..g Internet
BSC
RNC 11
PDP context activation accepted, now browse to
SGSN Gn
GGSN Gi 13
Internet DNS

13. 4G network architecture
MME – Mobility Management Entity; mobility management, (c-plane)
SGW – Serving Gateway; mobility management (u-plane), handover management
PGW – Packet Data Gateway; route to packet ntwk; like GGSN
HSS – Home Subscriber Server; new version of HLR

14. Create Session Request response (Accept)
Sample 4G call flow
Herewith the IP Addresses
Reference : TS TS TS
Attach request..
Herewith the info 5 3 1
HSS
DNS MS
eNodeB
Get info for this subscriber
What is the S-GW IP Address ?
What is the P-GW IP Address ? S1 2 4
I am attached to the network and want to browse to
MME
Create Session Request with IP Address of S-GW and P-GW 6
S1u
Packet Data Network
e..g Internet
S11 11
Create Session Request response (Accept)
S-GW
P-GW 10
SGi
S5/S8 8
Create Session Request with IP Address of P-GW 7
Create Session Request response (Accept)
Create Session Request response (Accept) 9

15. I am attached to the network and want to browse to www.google.com.au
Sample 4G call flow
Reference : TS TS TS
HSS
DNS MS
eNodeB S1
I am attached to the network and want to browse to
MME
S1u
Packet Data Network
e..g Internet
S11 11 12
S-GW
P-GW
SGi
S5/S8 13
Internet DNS

16. Additional equipment
IMS – IP Multimedia Subsystem; used for LTE-to-LTE communications instead of SGW/PGW
Gigamon – Used to monitor network statistics and performance
Dedicated subsystem for Key Performance Indicators (KPI)
Closely monitored by RF Performance teams

17. 2G/3G/4G Differences
What’s the big deal?

18. 2G vs G
Speed limited to about 14.4 kb/s (114 kb/s GPRS; 237 kb/s EDGE)
No multimedia streaming functionality
Limited roaming ability
Limited data packet support
Relies on circuit switching for voice calls
Speed around 384 kb/s (7.2 Mb/s down, 384 kb/s up HSPA)
Asymmetric data; small data up (request), large payload down
BoD – Bandwidth-on-demand; network dynamically assigns bandwidth based on request
Always-on; can send/receive unexpected data

19. 3G vs 4G Speed around 384 kb/s (7.2 Mb/s down, 384 kb/s up HSPA)
Asymmetric data; small data up (request), large payload down
BoD – Bandwidth-on-demand; network dynamically assigns bandwidth based on request
Always-on; can send/receive unexpected data
Non-LTE (HSPA+) speed around Mb/s down, Mb/s up
LTE data speed peaks at 100 Mb/s down, 50 Mb/s up
Simplified; not as much MSO equipment needed as data is packet-switched
Voice sent over VoLTE (packets) or 3G CS

20. VoLTE
Voice over LTE; sends voice calls via packets rather than relying on circuit network
Allows network to be streamlined and rely solely on PS
Slightly longer connection time than CS
Higher-resolution audio; faster transmission speeds
Allows for video calling like FaceTime or Android Video Calling