AT&T Proprietary (Internal Use Only) Not for use or disclosure outside the AT&T companies
except under written agreement
LTE Overview
October 6, 2011
Robert Barringer
Enterprise Architect
LTE – Long Term Evolution
•The 4G Wireless Communications Specification From The 3GPP
•Only IP Communications
•A Set Of Enhanced Network
Infrastructure Elements in Support of Enhanced Network Features and Controls
•The Platform For Future Rich-Interactive Multimedia Communications
LTE Is…….
LTE Path Forward
LTE Worldwide Subscribers *
Juniper Research
500,000
300M
Our Approach
•Consistent with worldwide standards
•Efficient path to LTE
•Fallback to faster HSPA
•Aligned with industry timing, device availability
•Market Launch underway
•Fastest overall experience
•First wireless network designed with true Enterprise focus (data)
*Reported by CNET, August 2010
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Standard Platform for IP Services Communications
Enables fast and effective multimedia communications
Smooth Efficient Path to LTE
HSPA vs. CDMA
CDMA 14.4 kbpsPeak
Technology Shift
LTE
• Significant technology shift to LTE
• Limited device options in early years
• Fallback to slower EV-DO
• Consistent with worldwide standards
• Efficient path to LTE
• Fallback to faster HSPA
2X to 3X speed advantage
EV-DO Peak 1.6 Mbps
GPRS Peak 48 Kbps
EDGE Peak 237 Kbps
4G - HSPA+ Peak 21 Mbps
4G - LTEPeak 100 Mbps
HSDPA Peak 3.6 Mbps
HSPA 7.2 Peak 7.2 Mbps
UMTS Peak 384 Kbps
Backwards Compatible Present Future
HSPA
CDMA
Based on theoretical peak speeds. Actual speed experienced will be less.
*Based on HSPA 7.2 theoretical max
Worldwide Ecosystem
LTE Performance Specifications
(3GPP TR 25.913)Throughput (in Mbps)
Average download 5-12 Mbps, upload 2-5 Mbps 5 UE Categories (Cat 3: 100/50 peak)
Latency
Latency of less than 10 ms in unloaded condition
Dormant to active state transition time of less than 50 ms.
Mobility
Higher mobile speed between 15 and 120 km/h supported with high performance.
Mobility across the cellular network maintained at speeds from 120 km/h to 350 km/h (or even up to 500 km/h depending on the frequency band).
MIMO = Multiple Input/Multiple Output antenna technology
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DOWNLINK 5 MHz 10
MHz 20 MHz
2x2 MIMO 43 86 173
4x4 MIMO 82 163 326
UPLINK
2Rx,1Tx 5 MHz 10
MHz 20 MHz
16 QAM 12 25 58
64 QAM 18 40 86
Spectrum Holdings from FCC
AT&T will not be compatible with VZ networks because of different spectrum and equipment.
AT&T spectrum
Verizon spectrum
LTE Security Architecture
128-bit encryption and integrity keys. Possibility to migrate later to
256 bits
Snow3G (UMTS based) and AES (by US NIST) algorithms 1) Distribution of authentication data
X2 IPSec
2) Challenge / response authentication and key agreement (AKA)
UE
3) Encrypt + integrity pr. (CP) 3) Encrypt (UP)
Home network
HSS
Switching / Routing Visited network
UICC
K K,CK,IK
eNB CK,IK
SAE-GW 3) Encrypt+integrity pr. (NAS* control signals)
KASME To other
networks KeNB, KNAS
S1 IPSec
MME Challenge Response
Encryption termination in eNB
•LTE uses AES 128 bit OTA encryption
•Specification allows for future upgrade to 256 bit encryption
CP = Control Plane UP = User Plane
NAS = Non-Access Stratum protocol
Access Stratum = communications between UE & eNode B Non-Access Stratum = communications between UE and
core network elements
LTE NETWORK ELEMENTS
LTE Reference Architecture
eNode- B
MME
Serving Gateway
HSS
PDN Gateway 2G/3G
SGSN
PCRF
Operator’s IP services (e.g., IMS,
CCS)
ePDG 3GPP
AAA
Untrusted Non-3GPP IP Access Trusted
Non-3GPP IP Access 3GPP
ACCESS
Home PLMN
Non 3GPP Networks
•QoS
S1-C
S1-U
MSC
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Standards allow
Connectivity between other networks
New
IP Network
2G SGSN GGSN
PS Core PGW
3G SGSN
Gn
Gn
Gi
CS Core
Architectural Convergence 3G 4G/HSPA+, LTE
A-Bearer
RNCRNC UTRAN
Iub
Iub Iur Node B
3G/4G HSPA+
eUTRAN
eNodeB X2
4G LTE
S1 S1
SS7 SIGTRAN 2G MSC Call Server
A-Control
2G-MGw
3G-MGw
BSC
GERAN
BTS Abis
2G EDGE
3G MSC Call Server
NodeB
D
HLR
SCP
BSC: Base Station Controller BTS: Base Transceiver Station HLR: Home Location Register
GERAN: GSM EDGE Radio Access Network GGSN: Gateway GPRS Support Network LTE: Long Term Evolution
SMSC: Short Message Service Center MMSC: Multimedia Message Service Center
MSC: Mobile Switching Center NTN: National Tandem Network RNC: Radio network Controller SGSN: Serving GPRS Support Network
UTRAN: Universal Terrestrial Radio Access Network IM GW: Instant Messaging Gateway
IMS Core
CSCF
PCRF AS
HSS NTN PSTN
H.248
Email GW IM GW
Messaging Core
MMSC
SMSC
Other Packet Networks 850Mhz &
1900Mhz
700Mhz
eNodeB
Co-existence
LTE Architecture Overview 2G/3G Correlations
• eNode B (Enhanced Node B) – base station
• MME (Mobility Management Entity)
–
Connected to the MSC
–
Handles similar paging functions
• SGW (Serving Gateway)
–
Akin to an Enhanced SGSN
• PGW (PDN Gateway)
–
Enhanced GGSN with firewall functionality built in
• HSS (Home Subscriber Server)
–
HLR with presence (location) and application specific support build in
• PCRF (Policy Control and Routing Function)
–
Has not equal in the 2G/3G environment.
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AT&T / LTE FUTURES
AT&T’s Roadmap for Voice Capabilities over LTE
1. Initial launch of LTE -- support data only. No Voice capabilities.
2. Phase 2 -- Circuit Switched Fall Back (CSFB)
1. Voice calls will be pushed to 3G or 2G
2. CS or PS Fall Back are defined in the
standards (thru the 3G-SGSN or thru the MSC).
3. Phase 3 -- Voice over LTE (VoLTE).
1. True native mode on LTE (IP Based)
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Voice over LTE
• Circuit Switch Fall Back (CSFB)
– LTE UE performs IRAT to 3G or 2G to establish voice call
– Device registered on both LTE and UMTS/GSM networks
– Pages delivered over SGs interface from MSC to MME
– Active data session may be handed over to UMTS/GSM
• One Voice (VoIMS) – Standard Supported By AT&T
– No Circuit Switch requirement
– Jointly developed by carriers and vendors to support voice and SMS over IMS
– SIP based, real time media negotiation
– SRVCC required to maintain call continuity at LTE – 2G/3G border
LTE Is Data Only & Requires An Overlay Voice Architecture
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