Long Term Evolution (LTE) and System Architecture Evolution (SAE)
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Transcript of Long Term Evolution (LTE) and System Architecture Evolution (SAE)
www.nethawk.fi
3 May 2007
Long Term Evolution (LTE) and System Architecture Evolution (SAE)
www.nethawk.fi
3 May 2007
Contents
> 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
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3 May 2007
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 servicesHigh quality needs to be quaranteed> Alternative solution for non-3GPP technologies (WiMAX) needed
> LTE will enhance the system to satisfy these requirements.
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LTE Overview
> 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
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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)
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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.
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3 May 2007
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
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LTE/SAE Keywords
> 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
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eNB
aGW
S1
eNB
S8
X2
aGW
eNB
X2
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 S1-C (to CPE) >Single node failure has limited effects
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> SAE architecture [3GPP TS 23.401]
GERAN
UTRAN GPRS Core
MME UPESAEGW
PCRF
Operator IP services
(including IMS, PSS, ...)
Non-3GPP IP Access
Evolved Packet Core
S11
S2
S3 S4
S7
S6
SGiS1
Gb
IuRx+
X1
eNB
X1
eNB
X2
Evolved RAN
aGW
PDNSAE GW
S5
HSS
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SAE architechture [3GPP TS 23.401]TBD
eNB
TBD
eNB
aGW
S1
TBD
eNB
S8
X2
Operator IP service, including
IMS
SAE GW
S11
PDNSAE GW
S11S5
SGi
Evolved RAN
HSS PCRF
IASA
aGW = MME/UPE
aGW
S6aS7
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Functions of eNB
> Terminates RRC, RLC and MAC protocols and takes care of Radio Resource Management functions
– 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
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Functions of aGW
> Takes care of Mobility Management Entity (MME) functions– 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
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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
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Functions
S1
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RRC
RLC
MAC
PHY
PDCP
RRC
RLC
MAC
PHY
PDCP
NAS NAS
aGWUE eNB
S1
> LTE Control Plane
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> LTE User Plane
RLC
MAC
PHY
PDCP
RLC
MAC
PHY
PDCP
aGWUE eNB
IP IP
S1
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GTP-U tunneling
SAE GWUPEeNB ServerUEUE
Radio L1Radio L1
MACMAC
PDCPPDCPIPv6/v4
u
ApplicationApplication
TCP/UDP
RLCRLC
L1L1
L2L2
IP
UDPUDP
GTP-UGTP-U
L2L2
L1L1
IP
UDPUDP
GTP-UGTP-U
L2L2
L1L1
IP
UDPUDP
GTP-UGTP-U
L2L2
L1L1
IPv6/v4
TCP/UDPApplication
L1L1
L2L2
L1L1
L2L2
X1X1 S1S1 S11S11 SGiSGi
IP
UDPUDP
GTP-UGTP-U
L2L2
L1L1
IP
UDPUDP
GTP-UGTP-U
L2L2
L1L1
S5S5PDN
SAE GW
Header compression & encryption
IP
UDPUDP
GTP-UGTP-U
L2L2
L1L1Radio Radio L1L1
MACMACRLCRLCPDCPPDCP
ENCENC
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Non-3GPP access tunneling
PDN
SAE GW
HA
AP ServerUEUE
L1L1
L2L2IP
L2L2
L1L1
IPv6/v4
TCP/UDPApplication
L1L1
L2L2
L1L1
L2L2
WLANWLAN S2S2 SGiSGi
L2L2
L1L1
IP
MIPIPv4/6
IPUDP
IP
MIPIPv4/6
UDP
IP
L2L2
L1L1
IP
L2L2
L1L1
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3 May 2007
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
> 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?
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LTE standardisation status
> 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 2008 2009
CommercialRelease
TrialsSpecification
First 3GPP specs expected 3Q/2007
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3 May 2007