Network Architecture How does it all work? Charts and acronym explanations sourced from: https://www.slideshare.net/yusufd/introduction-to-mobile-core-network-17667704

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

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

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”

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

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.

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

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

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

Get info for this subscriber Sample 2G/3G call flow Reference : TS 23.060 TS 24.008 TS 29.060 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

Create PDP Context accepted Sample 2G/3G call flow Reference : TS 23.060 TS 24.008 TS 29.060 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 www.google.com.au 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

PDP context activation accepted, now browse to Sample 2G/3G call flow Reference : TS 23.060 TS 24.008 TS 29.060 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 www.google.com.au SGSN Gn GGSN Gi 13 Internet DNS

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

Create Session Request response (Accept) Sample 4G call flow Herewith the IP Addresses Reference : TS 29.281 TS 23.401 TS 29.274 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 www.google.com.au 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

I am attached to the network and want to browse to www.google.com.au Sample 4G call flow Reference : TS 29.281 TS 23.401 TS 29.274 HSS DNS MS eNodeB S1 I am attached to the network and want to browse to www.google.com.au MME S1u Packet Data Network e..g Internet S11 11 12 S-GW P-GW SGi S5/S8 13 Internet DNS

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

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

2G vs 3G 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

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 21-42 Mb/s down, 5.76-22 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

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