Wireless Systems beyond 3G

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Wireless Systems beyond 3G
Not so many answers! Mainly questions and
comments!

• Erik Dahlman
• Expert Radio Access Technologies
• Ericsson Research

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Air-interfaces beyond 3G

• Two paths
• Evolution of 3G air-interface standards
• Development of new Broadband Air-interface (4G)

What path to follow?
Is there a fundamental difference? Sufficiently
evolved 3G 4G ?
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What do we want for the future?

• New and/or improved services
• Possibility for higher data rates
• Possibility for lower delay
• ...

• Lower cost
• Improved capacity and coverage
• More efficient spectrum utilization
• Reduced deployment effort/cost
• Lower-cost equipment (?)

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Evolution of 3G Air-interface Standards
Why an evolution of 3G standards?

• To satisfy new and/or changing user requirements
• To ensure competitiveness
• WCDMA competitive to other 3G technologies (and
  vice verse)
• 3G competitive to alternative technologies

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Evolution of WCDMA (WCDMA Evolved)
Rel 4
Rel 5
Rel 7
4G?
WCDMA Evolved
WCDMA
OFDM ?
Enhanced Uplink?
Enhanced Downlink (HSDPA)
MIMO ?
Wider Bandwidth
?
Similar evolution in 3GPP2 (cdma2000)
... ?
... ?
HSDPA High Speed Downlink Packet Access
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WCDMA Enhanced Downlink (HSDPA)
Basic principle Adapt to variations in
instantaneous radio-channel conditions!
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What does HSDPA offer?

• Support for very high data rates
• Peak data rate ?14 Mbps (theoretical)
• Actual peak data rate depends on e.g. channel
  conditions

• Improved capacity
• 100-200 improvement for best-effort packet
  data (e.g. web-browsing)
• Improved capacity also for streaming services
  (?50)

• Significantly reduced delay
• Higher data rates
• Shorter TTI
• Fast retransmissions

• Improved end-user quality
• Improved overall efficiency when interacting
  with higher-layer protocols

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WCDMA Enhanced Uplink

• HSDPA is a significant improvement to the WCDMA
  downlink
• Higher downlink capacity
• Reduced downlink delay

• Uplink may be a future bottle-neck
• In terms of capacity
• In terms of delay (contribution to overall
  round-trip delay)

Need to consider means to enhance/evolve the
WCDMA uplink ! Study item in 3GPP
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Enhanced Uplink, what are the targets?

• Improved uplink capacity
• Reduced uplink delay
• Improved coverage for high data rates
• NOTE! Higher peak data rates is not a main target
  !

• Techniques/features to be considered
• Improved scheduling
• Fast Hybrid ARQ with soft combining
• Shorter TTI

• Fast DCH set-up

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MIMO within 3G Evolution

• What is MIMO?
• Any transmission scheme with multiple TX and RX
  antennas?
• or
• Multi-layer schemes (á la BLAST)?

• Multi-layer schemes
• Clearly interesting for the future
• Within the scope of 3G evolution or for future
  air interface?

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3G Evolution towards Wider Bandwidth

• Further evolution of 3G air-interface
  standardsmay require wider transmission bandwidth

Alternatives
WCDMA
Super-wideband CDMA
Multi-carrier WCDMA
5 MHz
Is this still 3G?
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Enhancements within the 3G standards

• Carried out in parallel to 3G evolution
• Continuous work on means to improve 3G systems
• New/advanced receiver structures
• New/advanced antenna structures
• New/advanced radio-network algorithms
• etc. etc.
• Mainly to improve system performance (capacity
  coverage)

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New Broadband Air-Interface

• Research on Advanced Air-interface and
  Radio-network Technologies

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Why a New Broadband Air-interface?
WWW New Radio
The need for new radio interface systems with
significantly improved capabilities is motivated
with the changed expected user behaviour towards
the knowledge society to support future societal
needs based on sustainable scenarios
Final version
The need for new radio interface systems with
significantly improved capabilities is motivated
with changed expected user behaviourthat can not
be satisfied with existing and evolving systems!
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Why a New Broadband Air-interface?

• To provide new wireless services not possible to
  providewith 3G evolution
• To provide key wireless services much more
  efficientlycompared to 3G evolution

Do such services exist ?
They may and one needs to be prepared for it !
Research on New Broadband Air-interface needed !
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Requirements on Future Broadband Air-interface

• as stated within WWI, Japan (NTT DoCoMo), etc.

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Data-rate requirements

• High Maximum Air-interface Data Rate
• Downlink gt 100 Mbps gt1 Gbps in special
  scenarios
• Uplink ?

Very large maximum transmission bandwidth needed !

• High Achievable Maximum Data Rate
• High data rates in difficult radio environments
  (e.g. severe time dispersion)
• High data rates at high terminal speed
• High data rates with wide-area coverage (with
  reasonable TX power ! )

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Some additional requirements

• Low delay

• High system capacity
• What is high? Much better than 3G?
• Improved cell capacity Mbps/MHz/cell
• Advanced antenna solutions
• Efficient operation in small cells
• New radio-network structures
• How important is this?

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Requirement on Spectrum Flexibility

• Need for very large maximum transmission
  bandwidth
• Spectrum limitations

• Spectrum flexibility needed
• Multiple frequency bands
• Differently-sized spectrum allocations

• Support for multiple transmission bandwidths
• Support for different duplex arrangements

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Some Important Technologies
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Some Important Technologies

• New / Advanced Transmission Schemes
• OFDM / multi-carrier
• Advanced receiver structures
• etc. etc.

• Wideband Radio Technologies

• Advanced Antenna Solutions
• Multiple antenna elements at network and terminal
• Advanced antenna solutions should be an
  integrated part of a future broadband
  air-interface

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Some Important Technologies, cont

• Tight Interlayer Interaction
• Tight interaction between the resource management
  andthe physical layer
• Fast measurements and control
• Exploit the spatial, frequency, and multi-user
  dimensions

• New Radio-network Structures/Topologies
• Relaying/multi-hop solutions?
• Cellular MUD
• Other novel approaches

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Beyond 3G _at_ Ericsson

• Main focus on 3G evolution
• High Speed Downlink Packet Access (Enhanced
  Downlink)
• Enhanced Uplink
• Further enhancements/evolution of 3G standards

• Future Broadband Air-interface
• Basic research on advanced air-interface and
  radio-network technologies
• Long-term 3G evolution or 4G?
• WWI, Asian 4G discussions (Japan, China, etc.)

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Thank you for your attention!

• erik.dahlman_at_eab.ericsson.se