technical approaches for 3gpp2 evolution dr. byung k yi chair, tsg-c lg electronics [email protected]
TRANSCRIPT
2
• Executive Summary
• Background
• Spectral Efficiency– Spatial Processing
– Interference Reduction
• Higher Data Rate– Multi-carrier DV/HRPD
– New Air Interfaces
• Multiple Antenna Technologies
• Other Features
• Summarizing Remarks
• Technical Contributions
Outline
3
• Significant support has been expressed for cdma2000 evolution
• Air Interface Evolution (AIE) Technical Experts Meeting (TEM) for 3GPP2 Evolution was held during 10-11 March 2005 in Denver, CO, USA.
• AIE TEM workshop was intended to share the views of the future 3GPP2 Evolution.
• 10 Requirement and 11 Technical contributions were presented.
• Phased approaches for evolution were proposed and discussed.
• This presentation summarizes proposed technical solutions for phased evolution.
Executive Summary
4
• Proposed specifications for future wireless cellular systems included :– Increased spectral efficiency : 4 bps/Hz
– Higher peak data rates and system capacity• Long-term targets for peak data rate
– FL : 100 Mbps ~ 1 Gbps
– RL : 50 ~ 100 Mbps
• The following analyses and approaches were suggested.
Background
5
• To achieve higher data rate and reduced cost per bit, higher spectral efficiency ( 4 bps/Hz) is required
• Spatial signal processing has opened another domain in addition to time and frequency domain to provide higher spectral efficiency Space Domain.
• In cellular environments, inter-cell interference is a major hurdle for higher spectral efficiency.
Spectral Efficiency (1/5)
6
• Trend of cellular systems indicates that higher spectral efficiency and lower Eb/No are required in future systems [1].
Spectral Efficiency (2/5)
0.01
0.1
1
10
Spect
ral Effi
ciency
[b
it/s
/Hz]
100 20 30 40Eb/No [dB]
IS-95
CDMA 1x
GSMAMPS
EVDO
Requirement : 4 [bit/s/Hz]
FL receiver performance requirements (fading ch.) [3]
Based on voice user capacity reported at CDG website[2]
7
• Further increase of spectral efficiency with less Eb/No is very hard as the theoretical limit is approached. Spectral efficiency is increased by increasing Eb/No in 1xEV-DO [1].
Spectral Efficiency (3/5)
Requirement : 4 [bit/s/Hz]
0.01
0.1
1
10
Spect
ral Effi
ciency
[b
it/s
/Hz]
100 20 30 40Eb/No [dB]
IS-95GSM
AMPS
FL receiver performance requirements (fading ch.) [3]
FL receiver performance requirements (AWGN) [3]
Based on voice user capacity reported at CDG website[2]
CDMA 1xEVDO
Shannon limit
EVDO (~Peak rate)
8
• Not all users achieve higher spectral efficiency due to another constraint imposed by interference [1].
Spectral Efficiency (4/5)
FL receiver performance requirements (fading ch.) [3]
FL receiver performance requirements (AWGN) [3]
Based on voice user capacity reported at CDG website[2]
Shannon limit
Requirement : 4 [bit/s/Hz]
0.01
0.1
1
10
Spect
ral Effi
ciency
[b
it/s
/Hz]
100 20 30 40Eb/No [dB]
IS-95GSM
AMPS
CDMA 1xEVDO
EVDO (~Peak rate)Interference
bound(Freq. reuse = 1)
9
• Addition of space domain and reduction of interference are key factors for higher spectral efficiency in future cellular systems.
Spectral Efficiency (5/5)
Requirement : 4 [bit/s/Hz]
0.01
0.1
1
10
Spect
ral Effi
ciency
[b
it/s
/Hz]
100 20 30 40Eb/No [dB]
IS-95GSM
AMPS
CDMA 1xEVDO
EVDO (~Peak rate)2: Interference
Reduction
1: Spatial Multiplexing
Target
10
• Exploiting the spatial dimension in signal processing for cellular communication networks to improve :– Coverage
– Signal Quality
– Spectral Efficiency
• Higher spectral efficiency comes by means of spatial multiplexing.– Multiple spatial data pipes between TX and RX
Spatial Processing (1/4)
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• 5% outage / 95% reliability vs. SNR as a function of the number of TX and RX antennas. Bandwidth is 200 KHz : Source : Paulraj, Stanford University
Capacity Gain
Spatial Processing (2/4)
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• SDMA with fixed beams– Low complexity Beam selection only
– Max. 6 spatial multiplexing using overlapped 12beams (12 antennas)
Spatial Processing (3/4)
Dir
ect
ional G
ain
[dB
]
0
-5
-10
-15
-20
-25
-30
-35
-40-150-120 -90 -60 -30 0 30 60 90 120 150
Angle [degree]
#a #b #c #d #e #f#g #h #i #j #k #l Beam IDs
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• Spatial Multiplexing (SM) Technologies– Multiple antenna technique for achieving
higher data rate efficiently– Independent data streams transmitted on
each antenna– Requires multiple receive antennas and
sophisticated SM receiver processing– Works best in scattering channels
Spatial Processing (4/4)
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• BS cooperation approach to reduce inter-cell interference :• Each MS measures and reports which beam cause inter-cell interference.• BSs make schedules in cooperation to avoid beam collision.
• Advanced Signal Processing Techniques– Enhanced forward link equalizer– Interference Cancellation– MUD
Interference Reduction (1/2)
BS1 BS2
Receive data fromBS2-beam3without interference
Receive data fromBS1-beam4without interference
Interference due to beam collision
Exchange beam schedule
1
2
3
4
1
2
3
4 MS1
MS2MS3
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• Achievable envelope of spectral efficiency by varying the degrees of spatial multiplexing and interference reduction [1]
Spatial Multiplexing + Interference Reduction
x12x6
x3x2x1
0.1
1
10
100Spect
ral Effi
ciency
[b
it/s
/Hz]
40100 20 30 40Eb/No [dB]
3dB
6dB
10dB
14dB
20dB
Requirement : 4 [bit/s/Hz]
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• To satisfy ever increasing service demands requiring even higher transmission rate :– Suggested short-term targets for peak data rate
• FL : up to 15 x 3.1 Mbps ~ (up to 46.5 Mbps)
• RL : up to 15 x 1.8 Mbps ~ (up to 27 Mbps)
– Suggested long-term targets for peak data rate• FL : 100 Mbps ~ 1 Gbps
• RL : 50 Mbps ~ 1200 Mbps
Higher Data Rate
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• N x cdma2000 : Phase I
– Maximize Return on Investment (ROI) by maintaining backward compatibility for short-term
– Fast time-to-market to maintain a market leadership– Number of 1.25 MHz carriers, N, 15 N 1– Both symmetric and asymmetric FL/RL assignments
• Minimum N = 1 for backward compatibility
Multi-carrier cdma2000 (1/5)
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• Symmetric and asymmetric carrier assignments. Example of asymmetric assignment is FTP download [11].
Multi-carrier cdma2000 (2/5)
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• N x cdma2000 : Phase II
• Enhancements of existing Multi-carrier cdma2000 :
– Backward compatibility
– Rapid time-to-market for broadband services
– Technologies under consideration :
• Interference Cancellation
• Enhanced FL Equalizer
• Advanced FEC
• Antenna Techniques
Multi-carrier cdma2000 (3/5)
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• Coexistence of new modulation over existing multi-carrier HRPD :
– Providing improved spectrum utilization and peak data rates while maintaining backward compatibility
– New modulation : OFDM
– OFDM symbols in cdma2000 slots
– Value-added Technologies :• MIMO
• SDMA
Multi-carrier cdma2000 (4/5)
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• Example : 1xEV-DO, NxEV-DO, and broadband OFDM coexist in the same N = 3 carriers [10].
Multi-carrier cdma2000 (5/5)
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• Bandwidth up to 20 MHz or more
• Peak data rates– FL : 100 Mbps ~ 1 Gbps
– RL : 50 Mbps ~ 100 Mbps
• Criteria for new AI– Ease of scalable bandwidth operation
– Excellent performance in frequency-selective channels
– Reduced handset complexities
– Easy accommodation of value-added technologies like MIMO
New Air Interfaces (1/5)
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• Possible Candidate Multiplexing Technologies :– OFDM
• Bandwidth scalability with orthogonal frequency separation
• Full utilization of frequency selectiveness• High performance in a multipath channel• Narrow sidelobes
– MC-CDMA• CDMA + OFDM
– DS-CDMA with higher chip rate– Single carrier with cyclic prefix and frequency domain
equalizer• Comparable performance to OFDM• Reduced peak-to-average power ratio (PAPR)
New Air Interfaces (2/5)
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• Graphical representation of OFDM in time and frequency domain [10]
New Air Interfaces (3/5)
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• Example : OFDM + CDMA [9]– One time slot (2048 chips) is divided into 4 OFDM-CDMA symbols– One carrier has 512 tones– Each chip is mapped to one tone
New Air Interfaces (4/5)
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• System level comparison of OFDM and 1xEV-DV with rake reception in 1.25 MHz based on Evaluation Methodology Document (EMD) [12]
New Air Interfaces (5/5)
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• Use of multiple antennas at the transmitter and receiver (MIMO)– Improves SNR through beamforming array gain
– Reduces CCI or MAI• Improves coverage, capacity, and data rate
– Enhances spatial diversity• Improves signal quality
– Increases spectral efficiency by means of spatial multiplexing
Multiple Antenna Technologies (1/3)
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• MIMO is a key technology for broadband wireless communications [12].
Multiple Antenna Technologies (2/3)
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• Spatial Processing :– MIMO
– Spatial multiplexing
– Space Time Codes (STC)
– Beamforming
• SDMA– 12 overlapping fixed beams : Hitachi
– BS cooperation to avoid beam collision : Hitachi
– Secondary pilot : Lucent
– Tx/Rx Diversity, Antenna Arrays : Motorola, Ericsson
Multiple Antenna Technologies (3/3)
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• Support of higher-order modulation (64 QAM) : Lucent
• Advanced reception with equalization and interference cancellation : LGE, Qualcomm, Motorola, Lucent
• Enhanced broadcast and multicast services (BCMCS) : Via Telecom– Cellular Digital Multimedia Broadcast (CDMB)
• Compatible with 1x and Nx CMDA channels
Other Features
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• Common Objectives for 3GPP2 Evolution– Increase data rate to maintain a market leadership over other
wideband systems
– Latency reduction
– Backward compatibility for near-term
• Two step phased approaches for evolution were proposed to leverage investments while exploiting the promising technologies for each phase
• Phase I– Cost effective and straightforward migration to provide higher
transmission rates and spectral efficiency
– Nx CDMA systems (1xEV-DV Rev. D and HRPD)
Summarizing Remarks (1/2)
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– Peak data rates :• FL Peak Data Rate: at least 3 x HRPD Rev A FL (3.01
Mbps) up to 50 Mbps• RL Peak Data Rate : at least 3 x HRPD Rev A RL (1.8
Mbps) up to 29 Mbps
• Phase II– Further enhancements beyond Phase I by providing higher data
rates and spectral efficiency– Peak data rates greater than 100 Mbps– Candidate Technologies :
• CDMA with Equalizer or Interference Cancellation• OFDM(A)• IFDMA• MIMO, SDMA• Advanced Modulation and Coding
Summarizing Remarks (2/2)
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1. C00AIE-20050310-021R2, “Hitachi Technical Approaches for Future RAN Evolution”, Hitachi, March 2005
2. http://www.cdg.org/technology/cdma_technology/capacity/capacity_comparison_paper.asp, CDMA Development Group
3. C.S0010-C, “Recommended Minimum Performance Standards for cdma2000® Spread Spectrum Base Station Release C”, January 2005
4. C00AIE-20050310-020, “cdma2000 Air Interface Evolution”, Ericsson, March 2005
5. C00AIE-20050310-022R1, “LGE’s View on 3G Evolution”, LG Electronics, March 2005
6. C00AIE-20050310-023R1, “NxHRPD Architecture and High Level Design”, Lucent, March 2005
Technical Contributions (1/2)
cdma2000® is the trademark for the technical nomenclature for certain specifications and standards of the Organizational Partners (OPs) of 3GPP2. Geographically (and as of the date of publication), cdma2000® is a registered trademark of the Telecommunications Industry Association (TIA-USA) in the United States.
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7. C00AIE-20050310-023AR1, “HRPD Evolution Technology Enhancements”, Lucent, March 2005
8. C00AIE-20050310-024, “Motorola’s View on cdma2000 Air Interface Evolution”, Motorola, March 2005
9. C00AIE-20050310-025, “A Look at Evolving cdma2000 Technical Approaches”, Nokia, March 2005
10. C00AIE-20050310-026, “3GPP2 Air Interface Evolution”, Nortel, March 2005
11. C00AIE-20050310-027R1, “cdma2000 Evolution Technical Summary”, Qualcomm, March 2005
12. C00AIE-20050310-028R1, “Key Technologies for cdma2000 Evolution”, Samsung, March 2005
13. C00AIE-20050310-029, “CDMB-Cellular Digital Multimedia Broadcast”, Via Telecom, March 2005
Technical Contributions (2/2)