Technical Impact of New Generation Mobile Communications System

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Technical Impact of New Generation Mobile
Communications System
International Forum on 4G Mobile Communications
May 14 2002 Dr. Yasushi Yamao Wireless
Laboratories NTT DoCoMo
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Contents
Market Trends Mobile Internet 3G
service launched in Japan and UK
Technical Trends for Systems Beyond 3G
Visible trends Technical impact
Wireless Access Technology Beyond IMT-2000
Review of current technologies DoCoMos
Proposal for Beyond 3G Wireless Access
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3
Market Trends
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Mobile Phone Penetration Rate
(December 2000)
(March. 2002)
Penetration Rate ()
France
Sweden
Holland
Singapore
Finland
Germany
Hong Kong
Italy
Korea
USA
Great Britain
China
Japan
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5
New Services ex. Mobile Internet
(Millions)
Number of Subscribers in Japan
Total Number of Mobile Phones
75.1
Sept.
Dec.
Jun.
Jun.
Sept.
Dec.
Sept.
Dec.
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Where do you use -mode services?
From DoCoMo chart (Feb. 1-15/2001) public
questionnaire results
Home
School, Office, Visiting Office
In town, On vehicle
Cafe, Shops
Anywhere
Votes 0 100 200 300 400 500
600 700 800
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DoCoMos IMT-2000 Service
Freedom Of Mobile multimedia Access
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FOMA -Advantages
High-grade Mobile Communication with W-CDMA
Mobile Multimedia High-speed Packet Data and
Video Communications Forward Link 384
kbps / Reverse Link 64 kbps, Multiaccess
Global Mobility Mobile Multimedia Environment
Everywhere
High Quality Communications Voice Quality
identical to landline phones Free from
Noise and Interference
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FOMA -Deployment
2001.5.30 Start of Introductory phase
service 2001.10.1 Fully commercialized basis
service
100,000
Around 4,500
May 30 2001
Oct.1 2001
Dec.1 2001
Apr. 1 2002
? Kanto area within Route 16
? Tokyo, Part of Yokohama and Kawasaki
? Add Osaka and Nagoya
? Major Japanese Cities
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FOMA -Terminals
Current Lineup
Visual
Standard (i-mode)
Data Card
FOMA P2401
FOMA N2001/2002
FOMA P2101V /D2101V
384k Packet, 64k Data,
Voice, 384k Packet/ i-mode, 64k Data, Multi
Access
64k Real-time Video, Voice, 384k Packet/ i-mode
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Technical Trends
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Visible Technical Trends
Communication and Computing technologies are
rapidly converging. Ex. Mobile Internet,
Mobile E-Commerce, Wireless LAN,
Software Defined Radio
Circuit Switching to Packet Switching Amount
of Data / Multimedia traffic will grow
significantly. Need Broadband Packet Access
scheme.
In order to incorporate a variety of
applications, Networks and Applications should be
basically independent in system architecture.
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Technological Impact (1)
1. IP Convergence in Layer 3 may enable Seamless
Service among heterogeneous NWs. -
Unified Mobility Management (Both Macro- and
Micro-mobility) is a key technologies. -
Security Measures will be more important
considering connection to Private NWs.
AP
Mid Layer
PHY Layer
Mobile Public NW
Fixed Public NW
Office LAN
Home LAN
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Integration of Current Access schemes
System Integration of different access elements
will be important in Systems Beyond 3G.
Then, - Performance of an integrated system
is limited by that of each element. Wireless
access is always the Bottleneck. - Current
access schemes have many constraints due to
backward compatibility. - A large volume of
IP-based traffic is expected in the future. -
Broadband Access Services (ADSL, Cable, Optical)
are deploying very rapidly in the fixed NW.
Is it sufficient to integrate Current Access
Elements ?
Look for efficient way of enabling Broadband
Mobile.
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Technological Impact (2)
New Broadband Packet Wireless Access Technology
will remarkably enhance system performance.
High-speed High-capacity Low delay Low
bit cost IP-based?
Nationwide
3.5G
Beyond 3G
3G
Citywide
Mobility
2G
(-2010?)
IMT-2000
(2001)
Premises
Nomadic Wireless Access (2002)
Millimeter-wave LAN
Indoor / FWA
10
0.1
100
1
Information Speed (Mbit/s)
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Wireless Access Technology Beyond IMT-2000
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Requirements
Requirements Technical objectives
High-speed transmission Max. 100 Mbps for
downlink Independent Up Downlink
speeds
High-capacity gt10 fold increase in 3G
RAN cost reduction - Bit cost to be
reduced remarkably by 3G.
- Including Best Effort
Service.
Congestion control / Wireless QoS - When
congestion occurs, speed for each terminal
is controlled to maintain connection. -
Differentiated priority service.
Good mobility - Supporting high-speed
mobility. - Wide-range variable rate
transmission is essential to extend coverage
to indoor areas and to establish smooth
handover to indoor systems

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Two Streams with Overlapped Goal
Cellar and Wireless LAN technologies will target
a close field.
Nationwide
Cellular
Beyond 3G
2G
3.5G
Citywide
3G
Mobility
Premises
Nomadic Wireless Access
Millimeter-wave LAN
Indoor / FWA
WLAN
10
0.1
100
1
Information Speed (Mbit/s)
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Current Multiple Access Technologies
For Seamless Area Coverage, Multi-cell
Structure is necessary. CDMA achieves the best
spectrum efficiency. For High Throughput,
Single-cell Structure is suitable because
it avoids inter-cell interference. OFDM
achieves the best spectrum efficiency.
However ????? - Each scheme is not best in the
other cell structure. - For the flexible area
coverage and service deployment with lower cost,
both Multi-cell and Single-cell environments
should be supported with maximum throughput.
Look for New Wireless Access Scheme that covers
both environments.
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Wireless Access Candidates in Forward Link

• SC/DS-CDMA (Single-carrier/DS-CDMA)
• MC/DS-CDMA (Multi-carrier/DS-CDMA)
• OFCDM (Orthogonal Frequency and Code Division
  Multiplexing)
• based on multi-carrier CDMA
• OFDM (Orthogonal Frequency Division Multiplexing)

• OFCDM is a promising candidate
• Frequency diversity effect associated with
• spreading and channel coding in the frequency
  domain
• Robust against MPI owing to lower symbol rate
• Flexible use of frequency, time, and code
  resources

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VSF (Variable Spreading Factor)-OFCDM
When the spreading factor SF 1, OFCDM is
equivalent to OFDM.
Different symbols are assigned in OFDM
Introducing variable spreading factor into OFCDM
can support both OFCDM (SF gt1) and OFDM (SF 1)
modes.

• Propose VSF-OFCDM
• Realization of high capacity regardless of cell
  structure
• and channel conditions with seamless
  deployment
• Link capacity of VSF-OFCDM is evaluated

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Comparison between OFCDM and OFDM (1)
Related to multi-cell environment
Spreading factor
Other cell interference
Multiplexed codes
Cell reuse factor
Sectorization factor

• Isolated cell environment

• OFCDM
• Inter-code interference limits
• (1/SF)Cmux lt 1.0 due to frequency
• selective fading

• OFDM
• No inter-code interference
• FOFDM 1

Inter-code interference!
Isolated cell
NOFDM gt NOFCDM
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Comparison between OFCDM and OFDM (2)

• Multi cell environment

• OFDM
• FOFDM 3
• Bandwidth per cell is 1/3

NOFDM lt NOFCDM
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Summary of Comparison
Isolated-cell SF 1 has advantage (No
inter-code interference) Multi-cell SF gt 1
realizes one-cell frequency reuse
direct capacity increase expected from
sectorization
SF gt 1
SF 1
Isolated cell
VSF-OFCDM flexibly realizes higher capacity
according to cell environment and propagation
conditions.
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