4G LTE Impacts to Mobile Backhaul
Joseph V. Mocerino
Fujitsu Network Communications
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Evolving Network
RNC
RNC
Node B
RNC
lub
MSC/MGW
lu-cs
MSC/MGW
lu-ps
RNC
lu-ps
MSC/MGW
lu-cs
lu-cs
GMSC
3G SGSN
lu-ps
GGSN
Internet
PSTN
RNC Base Station Controller
MSC Mobile Switching Center
MGW Media Gateway
SGSN Serving GPRS Support Node
GGSN Gateway GPRS Support Node
Technology
Interfaces
Physical Layer Spec
UMTS
Iu-b, Iu-cs, Iu-ps
ATMoTDM – DS1
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2
4G LTE Network
eNodeB
S1, X2
SGW
eNodeB
eNodeB
SGW
SGW
PDN GW
eNodeB
MGW
Internet
PSTN
eNodeB
SGW
PDN GW
MGW
LTE Radio Node
Serving Gateway
Packet Data Network Gateway
Media Gateway
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3
Understanding Wireless Capacity

Spectral Efficiency – it’s what really matters!

Spectral Efficiency = # bits of data per Hz of air spectrum (b/s per Hz)
 The higher the better
• More users per radio sector
• Faster speeds
• Faster downloads of multimedia content
• All for the same amount of wireless spectrum ($$$)

Why it matters to Mobile Backhaul?

Defines the upper limit to amount of bandwidth required at a cell site
• BW = spectral efficiency x amount of licensed spectrum

What determines Spectral Efficiency?

Primarily the modulation technique used on the air interface
• Improvements in each generation of technology 2G  2.5G  3G  4G
• 4G LTE uses an advanced modulation called OFDM
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4
Wireless Capacity Example

1.2 Mhz
Mobile backhaul capacity

GSM 2G
voice
Compare backhaul requirements by technology
3.5 Mhz
GSM/Edge 2.75G
• 3 sector cell site
• Typical licensed channel sizes
voice+data
5 Mhz
UMTS/HSDPA 3G
data
5 Mhz
LTE 4G
data
64QAM
16QAM
QPSK
Wireless Capacity Requirements
Voice
Spectrum
(MHz)
GSM 2G
1.2
GSM / Edge 2.75G
1.2
Data
Spectrum
(MHz)
Voice Spectral
Efficiency
(bit/s/Hz)
Data
efficiency
(bit/s/Hz)
0.52
#
Traffic Eng
sectors
% Peak
Total
bandwidth
(Mb/s)
# T1s
3
70%
1.3
1
2.3
0.52
1
3
70%
6.1
4
HSDPA 3G
5
0
2
3
70%
21.0
14
LTE 4G
5
0
3.8
3
70%
39.9
n/a
LTE 4G
10
0
3.8
3
70%
79.8
n/a
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5
Coping with T1 TDM Backhaul

Legacy T1 Services

Represents vast majority of Mobile backhaul today
 Stringent wireless carrier requirements (see below)
 Recommendation
• Transport TDM services in native format
• Meets stringent carrier requirements
• Avoid T1 CES penalties
Parameter
Wireless
Carrier RFP
MEF
Spec
SONET
Delay
< 5 ms
< 25 ms
< 100 us
Jitter
< 1 ms
< 10 ms
< 3.2 us
Availability
99.999%
99.95%
99.999%
< 5.3 min/yr
< 263 min/yr
< 5.3 min/yr
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T1 CES Issues

Trade off between delay &
efficiency
T1 Frame
193 bits
193 bits
125 us
CES Hdr

Packetization delay, jitter buffer
delay, network delay
 CES & Ethernet overhead adds to
inefficiency
12 B
IFG
4B
4B
4B
ECID
CW
RTP
8B
Preamble SD
T1 CES (SAToP or CESoETH)
Payload
4B
18 B
Eth Hdr
Eth Payload
FCS
Ethernet Frame
Eth Ovrhd
Circuit Emulation Efficiency (typ)
Jitter
Buffer
Buffer Size
(frames)
Max Ntwrk
Jitter (ms)
Buffer Delay
(ms)
80
10
5
Frames
Efficiency
Bandwidth
1
30%
5.1 Mb/s
4
63%
2. 5 Mb/s
8
76%
2.0 Mb/s
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TDM/Eth Hybrid Model
GSM
3G
LTE
T1
T1 FW4100ES
FW4500
or
FW9500
GSM
3G
LTE

Eth
Eth
DS1s,
DS3 or
OC-n
Fujitsu FLASHWAVE 4100ES
T1
T1 FW4100ES
Eth
Migration Example

FW4100 ES supporting current T1 TDM backhaul
 LTE requirements for Ethernet backhaul transport
• Install Ethernet cards

Traffic aggregated at MSC
• Separation & aggregation of traffic – both in native formats
• FLASHWAVE 4500 or FLASHWAVE 9500
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Migration to Hybrid TDM/Eth Network

Simultaneous support for native SONET & Ethernet
Leverage existing MSPP – seamless transition to native Ethernet
 Maximize invest of embedded infrastructure

Present Mode of
Operation
Hybrid TDM & EOS
Hybrid TDM &
Native Ethernet
GigE / Fast E
SONET
SONET
SONET
FW4100 ES
FW4100 ES
or
FW4100 ES
DS1/3s
DS1/3s
Ethernet
(EoS)
DS1/3s
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Ethernet
9
Ethernet Overlay Model
GSM
3G
T1
T1
FW4100ES
Eth
LTE
Eth
FW CDS
FW9500
DS1s,
DS3 or
OC-n
GSM
3G
LTE
T1
T1 FW4100ES
Eth
FW CDS
Fujitsu FLASHWAVE CDS

Ethernet Overlay Model

No TDM/Ethernet Integration
• Separate networks due to regulatory, operational, or administrative requirements

FLASHWAVE CDS / FLASHWAVE 9500 provide next generation packet architecture
• FLASHWAVE CDS at cell locations
• High density GigE / 100FX connections
• Carrier Ethernet
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Summary
 LTE
is changing the landscape

Based on an all IP/Ethernet network
 Flatter, more efficient network architecture
 Bandwidths growing 10 – 20 Mb/s initial, 40 – 60 Mb/s per cell site fully loaded
 Continued
Reliance on T1s
Multi-protocol world – T1s will be in network for 8 to 15 years
 Don’t be surprised if wireless customers demand native TDM transport

• Latency, Jitter, Protection Switching, Availability – they still matter

Ethernet backhaul a requirement for LTE/WiMax
 Transitioning

Mobile Backhaul to 4G
TDM/Ethernet Hybrid Model
• Best of both worlds
• Native T1 TDM Transport
• Native Ethernet transport
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