Evolution of the Air Interface v0 - Frank Rayal · Evolution of the Air Interface ... GSM IS-95A...
Transcript of Evolution of the Air Interface v0 - Frank Rayal · Evolution of the Air Interface ... GSM IS-95A...
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Evolution of the Air InterfaceFrom 2G Through 4G and Beyond…
Frank Rayal
BLiNQ Networks/
Telesystem Innovations
Presentation to IEEE Ottawa Section / Alliance of IEEE
Consultants Network (AICN) - 2nd May 2012
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Evolution of Wireless Systems
GSM
IS-95A
IS-136
PDC
GPRS
IS-95B
EDGE
cdma2000
UMTSHSDPA/
HSUPAHSPA+
1xEV-DO
1xEV-DV
LTE LTE-A
2G 2.5G 3G 4G
~1991 (GSM)
~1998(GPRS)
~2001(UMTS)
~2011(LTE)
Acronyms
GSM: Group Special Mobile/Global System for Mobilecommunications
UMTS: Universal Mobile Telecommunication System
PDC: Pacific Digital Cellular (Japan) HSxPA: High Speed (Downlink/Uplink) Packet Access
GPRS: General Packet Radio Service EV-Dx: Evolution – Data Only/Data and Voice
EDGE: Enhanced Data Rates for GSM Evolution LTE-(A): Long Term Evolution – (Advanced)
CDMA: Code Division Multiple Access
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Multiple Access Technologies
TDMA FDMA
CDMA OFDMA
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Performance Summary
System Modulation Bandwidth Theoretical Maximum Realistic
GSM GMSK 200 kHz ~ 40 kbps 9.6 kbps
GPRS GMSK 200 kHz 171.2 kbps 40 kbps
EDGE GMSK/8-PSK 200 kHz 384 kbps 60-70 kbps
UMTS
(R99)
QPSK 5 MHz DL: 384 kbps
UL: 384 kbps
100 kbps
HSDPA
(R5)
DL: QPSK - 16 QAM
UL: QPSK
5 MHz DL: 14.4 Mbps
UL: 384 kbps
DL: 800 kbps
UL: 100 kbps
HSUPA
(R7)
DL: QPSK - 64 QAM
UL: QPSK - 16 QAM
5 MHz DL: 14.4 Mbps
UL: 5.72 Mbps
DL: 4 Mbps
UL: 1 Mbps
HSPA+
(R8)
DL: QPSK - 64 QAM
UL: QPSK - 16 QAM
5 MHz DL: 14-42 Mbps
UL: 11.5 Mbps
DL: 4.5 Mbps
UL: 2 Mbps
LTE DL: QPSK-64QAM 5/10/20
MHz
DL: 150 Mbps
UL: 51 Mbps
DL: 37 Mbps
UL: 16 Mbps
HSPA+: MIMO or DC required for 42 Mbps. DC requires twice the bandwidth.
LTE: DL assumes 2x2 MIMO in 20 MHz, 64-QAM; UL assumes 1x2 SIMO in 20 MHz, 16-QAM.
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Next Generation Wireless Technologies (4G; +)
> OFDM-based air interface
> Common features to achieve high-data rates
– High Modulation & Coding Schemes (MCS)
– MIMO antenna systems
> Spatial Multiplexing
> Space Time/Frequency Coding
– Beamforming
> Common features for link integrity
– Turbo codes
– Hybrid-ARQ
– Adaptive Modulation/Link Adaptation
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3GPP Key Performance Targets for LTE
Parameter Absolute RequirementReference Base Line
(R6: HSDPA/HSUPA)Comment
Do
wn
lin
k
Peak transmission rate > 100 Mbps 7 x 14.4 Mbps LTE: 20 MHz FDD, 2x2 spatial multiplexing
Reference: HSDPA in 5 MHz FDD, single
antennaPeak spectral efficiency > 5 bps/Hz 3 bps/Hz
Average cell spectral
efficiency> 1.6 - 2.1 bps/Hz/cell 3 - 4 x 0.53 bps/Hz/cell
LTE: 2x2 spatial multiplexing, interference
rejection combining receiver.
Reference: HSDPA, Rake receiver, 2 receive
antennas
Cell edge spectral
efficiency> 0.04 - 0.06 bps/Hz/user 2 - 3 x 0.02 bps/Hz As above, 10 users assumed per cell
Broadcast spectral
efficiency> 1 bps/Hz N/A Dedicated carriers for broadcast mode
Up
lin
k
Peak transmission rate > 50 Mbps 5 x 11 Mbps LTE: 20 MHz FDD, 2x2 spatial multiplexing
Reference: HSUPA in 5 MHz FDD, single
antennaPeak spectral efficiency > 2.55 bps/Hz 2 bps/Hz
Average cell spectral
efficiency> 0.66 - 1.0 bps/Hz/cell 2 - 3 x 0.33 bps/Hz
LTE: single antenna transmission, IRC
receiver.
Reference: HSUPA, Rake receiver, 2 receive
antennas
Cell edge spectral
efficiency> 0.02 - 0.03 bps/Hz/user 2 - 3 x 0.01 bps/Hz As above, 10 users assumed per cell
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LTE Air Interface
eNB UE
> Downlink
– OFDMA based access, with QPSK, 16QAM and 64QAM modulation (adaptive selection)
– MIMO and transmit diversity
– Scheduling, link adaptation, HARQ
> Uplink
– Single Carrier FDMA (SC-FDMA) access with QPSK, 16QAM and 64QAM (optional)
> Scheduling, link adaptation, HARQ
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Orthogonal Frequency Division Multiplexing (OFDM)
FDMA
OFDM
Bandwidth Saving
> Narrowband sub-carriers fade independently
> Does not require sophisticated frequency equalizers at the receiver
> Overlapping carriers increases spectral efficiency compared to
conventional FDM
> Orthogonality between carriers mitigates interference
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Modulation Schemes
> Higher order modulation schemes result in highest spectral efficiency
BPSK: 1bps/Hz QPSK: 2bps/Hz ππππ/4-QPSK: 2bps/Hz
8-PSK: 3bps/Hz 16-QAM: 4bps/Hz 64-QAM: 6bps/Hz
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����Digital Modulation Reach Comparison
> Higher order modulation schemes require higher signal quality to demodulate
– Higher SNR results in reduced range; hence higher order modulation schemes have shorter range
> Control signaling typically uses BPSK or QPSK with low code rate
1% PER; 100 Byte Packet; PB Channel.
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����Spatial Multiplexing
Increases channel capacity by creating multiple parallel channels
with no additional power or BW requirements:
Capacity Gain = Min (Tx , Rx) antennas
S4S2
S3S1
TX RX
h11
h22
h21
h12
Y = H S + n
S1
S2
y1
y2
=
2212
2111
hh
hhH
S3S4 S2S1
S3
S4
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LTE-Advanced
LTE (R8) LTE-Advanced (R10)
Peak Data Rate (Mbps)Downlink 300 1000
Uplink 75 500
Bandwidth (MHz) 20 100
Peak Spectral Efficiency
(bit/s/Hz)
Downlink 16.3(1) 30(2)
Uplink 4.32(3) 15(4)
Spectral Efficiency
(bit/s/Hz/cell), 3 km/h,
500 m ISD
Downlink
2 x 2 1.69 2.4
4 x 2 1.87 2.6
4 x 4 2.67 3.7
Uplink1 x 2 0.74 1.2
2 x 4 -- 2.0
Cell-edge User
Throughput
(bit/s/Hz/cell/user),
5 percentile, 10 users,
500 m ISD
Downlink
2 x 2 0.05 0.07
4 x 2 0.06 0.09
4 x 4 0.08 0.12
Uplink1 x 2 0.02 0.04
2 x 4 -- 0.07
(1) 4x4 MIMO; (2) Up to 8x8 MIMO; (3) 64QAM SISO; (4) Up to 4x4 MIMO
ISD: Inter-site distance
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Reaching the Limits of Technology?
Source: Qualcomm; LTE-Advanced: Heterogeneous Networks, Feb 2010
Network Topology Key To Capacity Enhancements
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Fractional Frequency Reuse
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LTE-A Radio Interface Technologies
LTE-Advanced Maximum Bandwidth
Carrier 1 Carrier 2 Carrier 3 Carrier 4 Carrier 5
100 MHz
Joint transmission: DL/UL cooperative MIMO;
Joint processing of received signals
Coordinated Multiple Point
Transmission and Reception (CoMP)
Carrier Aggregation
���� Peak Data Rate
���� Spectral Efficiency
���� Cell-edge Performance
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Heterogeneous Networks
Enhanced ICIC (R10) Combined With Heterogeneous Networks
Pico-BS
Relay RF
Backhaul
C-RAN/RRH
Femto
(Indoor)
RelayCoverage
Hole
���� Spectral Efficiency
���� Cell-edge Performance
���� Coverage
���� Spectral Efficiency
���� Cell-edge Performance
���� Coverage���� Cell-edge Performance
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Key Take-Aways
> To maximize capacity, wireless technologies incorporate the
latest in physical layer innovations; BUT we are soon reaching
the limit in terms of peak link-level capacity from both
technology and practical perspectives
> Next generation wireless systems (LTE-Advanced) will
leverage ‘network-level’ techniques to maximize average
capacity
> Enhancements in capacity and performance will shift to
network topology and architecture
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Telesystem Innovations