Transcript Long Term Evolution (LTE) and System Architecture

3 May 2007
www.nethawk.fi
Long Term Evolution (LTE) and
System Architecture Evolution (SAE)
>v1.0 3rd May 2007
3 May 2007
www.nethawk.fi
Contents
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Why LTE/SAE?
LTE Overview
LTE technical objectives and architecture
LTE radio interface
RAN interfaces
SAE architechture [3GPP TS 23.401]
Functions of eNB
Functions of aGW
GTP-U tunneling
Non-3GPP access tunneling
Testing challenges with LTE
LTE standardisation status
3 May 2007
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Why LTE/SAE?
> Packet Switched data is becoming more and more dominant
> VoIP is the most efficient method to transfer voice data
 Need for PS optimised system
> Amount of data is continuously growing
 Need for higher data rates at lower cost
> Users demand better quality to accept new services
High quality needs to be quaranteed
> Alternative solution for non-3GPP technologies (WiMAX) needed
> LTE will enhance the system to satisfy these requirements.
3 May 2007
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LTE Overview
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3GPP R8 solution for the next 10 years
Peaks rates: DL 100Mbps with OFDMA, UL 50Mbps with SC-FDMA
Latency for Control-plane < 100ms, for User-plane < 5ms
Optimised for packet switched domain, supporting VoIP
Scaleable RF bandwidth between 1.25MHz to 20MHz
200 users per cell in active state
Supports MBMS multimedia services
Uses MIMO multiple antenna technology
Optimised for 0-15km/h mobile speed and support for up-to 120-350
km/h
> No soft handover, Intra-RAT handovers with UTRAN
> Simpler E-UTRAN architecture: no RNC, no CS domain, no DCH
3 May 2007
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LTE technical objectives and architecture
> User throughput [/MHz]:
– Downlink: 3 to 4 times Release 6 HSDPA
– Uplink: 2 to 3 times Release 6 Enhanced Uplink
> Downlink Capacity: Peak data rate of 100 Mbps in 20 MHz maximum
bandwidth
> Uplink capacity: Peak data rate of 50 Mbps in 20 MHz maximum
bandwidth
> Latency: Transition time less than 5 ms in ideal conditions (user
plane), 100 ms control plane (fast connection setup)
3 May 2007
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> Mobility: Optimised for low speed but supporting 120 km/h
– Most data users are less mobile!
> Simplified architecture: Simpler E-UTRAN architecture: no RNC, no
CS domain, no DCH
> Scalable bandwidth: 1.25MHz to 20MHz: Deployment possible in
GSM bands.
3 May 2007
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LTE radio interface
> New radio interface modulation: SC-FDMA UL
and OFDMA DL
– Frequency division, TTI 1 ms
– Scalable bandwidth 1.25-20MHz
– TDD and FDD modes
• UL/DL in either in same or in another
frequncy
– OFDMA has multiple orthogonal subcarries
that can be shared between users
• quickly adjustable bandwith per user
– SC-FDMA is technically similar to OFDMA but
is better suited for uplink from hand-held
devices
• Single carrier, time space multiplexing
• Tx consumes less power
From Ericsson, H. Djuphammar
3 May 2007
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LTE/SAE Keywords
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aGW
Access Gateway
eNB
Evolved NodeB
EPC
Evolved Packet Core
E-UTRAN
Evolved UTRAN
IASA
Inter-Access System Anchor
LTE
Long Term Evolution of UTRAN
MME Mobility Management Entity
OFDMA
Ortogonal Frequency Division Multiple Access
SC-FDMA
Single Carrier Frequency Division Multiple Access
SAE
System Architecture Evolution
UPE
User Plane Entity
3 May 2007
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RAN interfaces
>X2 interface between eNBs for
handovers
>Handover in 10 ms
>No soft handovers
>Interfaces using IP over
E1/T1/ATM/Ethernet /…
>Load sharing in S1
>S1 divided to S1-U (to UPE) and S1C (to CPE)
>Single node failure has limited
effects
S1
eNB
aGW
X2
S8
eNB
aGW
X2
eNB
3 May 2007
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> SAE architecture [3GPP TS 23.401]
GERAN
Iu
UTRAN
PCRF
HSS
Gb
GPRS Core
S6
Rx+
S7
X1
S3
eNB
X1
X2
S1
MME UPE
S4
S11
SAE
GW
S5
PDN
SAE GW
SGi
aGW
Evolved Packet Core
S2
eNB
Non-3GPP IP
Access
Evolved RAN
Operator IP
services
(including IMS,
PSS, ...)
3 May 2007
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SAE architechture [3GPP TS 23.401]
TBD
HSS
PCRF
S1
S7
S6a
eNB
S11
TBD
aGW
S5
PDN
SAE GW
SAE GW
X2
IASA
S8
SGi
eNB
S11
aGW
TBD
eNB
Evolved RAN
aGW = MME/UPE
Operator IP
service, including
IMS
3 May 2007
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Functions of eNB
> Terminates RRC, RLC and MAC protocols and takes care of Radio
Resource Management functions
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Controls radio bearers
Controls radio admissions
Controls mobility connections
Allocates radio resources dynamically (scheduling)
Receives measurement reports from UE
> Selects MME at UE attachment
> Schedules and transmits paging messages coming from MME
> Schedules and transmits broadcast information coming from MME &
O&M
> Decides measurement report configuration for mobility and scheduling
> Does IP header compression and encryption of user data streams
3 May 2007
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Functions of aGW
> Takes care of Mobility Management Entity (MME) functions
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Manages and stores UE context
Generates temporary identities and allocates them to UEs
Checks authorization
Distributes paging messages to eNBs
Takes care of security protocol
Controls idle state mobility
Control SAE bearers
Ciphers & integrity protects NAS signaling
3 May 2007
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> Takes care of User Plane Entity (UPE) functions
– Terminates for idle state UEs the downlink data path and
triggers/initiates paging when downlink data arrive for the UE.
– Manages and stores UE contexts, e.g. parameters of the IP bearer
service or network internal routing information.
– Switches user plane for UE mobility
– Terminates user plane packets for paging reasons
3 May 2007
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Functions
S1
3 May 2007
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> LTE Control Plane
UE
aGW
eNB
NAS
NAS
PDCP
PDCP
RRC
RRC
RLC
RLC
MAC
MAC
PHY
PHY
S1
3 May 2007
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> LTE User Plane
UE
aGW
eNB
IP
IP
PDCP
PDCP
RLC
RLC
MAC
MAC
PHY
PHY
S1
3 May 2007
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GTP-U tunneling
Header compression
& encryption
UE
X1
eNB
UPE
S1
S11
SAE GW S5
PDN
SGi
Server
SAE GW
Application
Application
TCP/UDP u
IPv6/v4
PDCP
RLC
TCP/UDP
ENC
PDCP GTP-U
RLC
MAC UDP
MAC
Radio L1
Radio
L1
IPv6/v4
GTP-U GTP-U
GTP-U GTP-U
GTP-U
UDP
UDP
UDP
UDP
UDP
IP
IP
IP
IP
IP
IP
L2
L2
L2
L2
L2
L2
L1
L1
L1
L1
L1
L1
L2
L2
L2
L1
L1
L1
3 May 2007
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Non-3GPP access tunneling
Server
PDN
AP
UE
S2
WLAN
SAE GW
SGi
Application
HA
TCP/UDP
IPv4/6
IPv4/6
MIP
UDP
MIP
UDP
IP
IP
L2
L2
L2
L1
L1
L1
IP
IP
IP
IP
L2
L2
L2
L2
L1
L1
L1
L1
IPv6/v4
3 May 2007
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Testing challenges with LTE
> How to optimize radio interface?
– No radio measurement data available since no ”Iub-like” interface
> Increased complexity of eNB
– need for analysis of internal traffic
– need for internal debugging
– need for analysis of protocol data
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How to test inter-eNB handovers?
How to test inter-system handovers?
How to test voice and video broadcast?
10x higher throughput  How to verify eNB performance?
How to test application level QoS? How to verify SLA?
How to handle network management challenges?
3 May 2007
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LTE standardisation status
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Specification work done by 3GPP TS RAN.
First 3GPP specs expected 3Q2007
First trials expected 2008
Commercial release expected 2009
NetHawk is member in 3GPP and follows closely the standardisation
work
2007
Specification
2008
Trials
First 3GPP specs expected 3Q/2007
2009
Commercial
Release
3 May 2007
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