Evolution of the Air Interface From 2G Through 4G and Beyond Presentation to IEEE Ottawa Section / Alliance of IEEE Consultants Network (AICN) - 2nd May 2012 Frank Rayal BLiNQ Networks/ Telesystem Innovations 2012 Telesystem Innovations Inc. 1
Evolution of Wireless Systems GSM GPRS EDGE LTE LTE-A PDC IS-136 IS-95A IS-95B UMTS cdma2000 HSDPA/ HSUPA 1xEV-DO 1xEV-DV HSPA+ 2G 2.5G 3G 4G ~1991 (GSM) ~1998 (GPRS) ~2001 (UMTS) ~2011 (LTE) Acronyms GSM: Group Special Mobile/Global System for Mobile communications PDC: Pacific Digital Cellular (Japan) GPRS: General Packet Radio Service EDGE: Enhanced Data Rates for GSM Evolution CDMA: Code Division Multiple Access UMTS: Universal Mobile Telecommunication System HSxPA: High Speed (Downlink/Uplink) Packet Access EV-Dx: Evolution Data Only/Data and Voice LTE-(A): Long Term Evolution (Advanced) 2012 Telesystem Innovations Inc. 2
Multiple Access Technologies TDMA FDMA CDMA OFDMA 2012 Telesystem Innovations Inc. 3
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) HSDPA (R5) HSUPA (R7) HSPA+ (R8) QPSK 5 MHz DL: 384 kbps UL:384 kbps DL: QPSK-16 QAM UL: QPSK DL:QPSK -64 QAM UL: QPSK -16 QAM DL:QPSK -64 QAM UL: QPSK -16 QAM LTE DL: QPSK-64QAM 5/10/20 MHz 5 MHz DL:14.4Mbps UL:384 kbps 5 MHz DL: 14.4 Mbps UL: 5.72 Mbps 5 MHz DL: 14-42 Mbps UL: 11.5 Mbps DL: 150 Mbps UL:51 Mbps 100 kbps DL: 800 kbps UL: 100 kbps DL: 4Mbps UL:1 Mbps DL: 4.5Mbps UL:2 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. 2012 Telesystem Innovations Inc. 4
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 2012 Telesystem Innovations Inc. 5
3GPP Key Performance Targets for LTE Parameter Absolute Requirement Reference Base Line (R6: HSDPA/HSUPA) Comment Peak transmission rate > 100 Mbps 7 x 14.4 Mbps LTE: 20 MHz FDD, 2x2 spatial multiplexing Reference: HSDPA in 5 MHz FDD, single Peak spectral efficiency > 5 bps/hz 3 bps/hz antenna Downlink 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 Broadcast spectral efficiency > 0.04-0.06 bps/hz/user 2-3 x 0.02 bps/hz As above, 10 users assumed per cell > 1 bps/hz N/A Dedicated carriers for broadcast mode Peak transmission rate > 50 Mbps 5 x 11 Mbps LTE: 20 MHz FDD, 2x2 spatial multiplexing Reference: HSUPA in 5 MHz FDD, single Peak spectral efficiency > 2.55 bps/hz 2 bps/hz antenna Uplink Average cell spectral efficiency Cell edge 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 > 0.02-0.03 bps/hz/user 2-3 x 0.01 bps/hz As above, 10 users assumed per cell 2012 Telesystem Innovations Inc. 6
LTE Air Interface > 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 enb UE 2012 Telesystem Innovations Inc. 7
Orthogonal Frequency Division Multiplexing (OFDM) FDMA Bandwidth Saving OFDM > 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 2012 Telesystem Innovations Inc. 8
Modulation Schemes BPSK: 1bps/Hz QPSK: 2bps/Hz π/4-qpsk: 2bps/Hz 8-PSK: 3bps/Hz 16-QAM: 4bps/Hz 64-QAM: 6bps/Hz > Higher order modulation schemes result in highest spectral efficiency 2012 Telesystem Innovations Inc. 9
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. 2012 Telesystem Innovations Inc. 10
Spatial Multiplexing h11 S 1 S 3 h21 y 1 S4 S3 S1 S2 TX h22 h12 RX S1 S2 S3 S4 S 2 S 4 y 2 Y = H S + n H = h h 11 12 h h 21 22 Increases channel capacity by creating multiple parallel channels with no additional power or BW requirements: Capacity Gain = Min (Tx, Rx) antennas 2012 Telesystem Innovations Inc. 11
LTE-Advanced LTE (R8) LTE-Advanced (R10) Peak Data Rate (Mbps) Downlink 300 1000 Uplink 75 500 Bandwidth (MHz) 20 100 Peak Spectral Efficiency Downlink 16.3 (1) 30 (2) (bit/s/hz) Uplink 4.32 (3) 15 (4) Spectral Efficiency (bit/s/hz/cell), 3 km/h, 500 m ISD Cell-edge User Throughput (bit/s/hz/cell/user), 5 percentile,10 users, 500 m ISD Downlink Uplink Downlink Uplink 2 x 2 1.69 2.4 4 x 2 1.87 2.6 4 x 4 2.67 3.7 1 x 2 0.74 1.2 2 x 4 -- 2.0 2 x 2 0.05 0.07 4 x 2 0.06 0.09 4 x 4 0.08 0.12 1 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 2012 Telesystem Innovations Inc. 12
Reaching the Limits of Technology? Network Topology Key To Capacity Enhancements Source: Qualcomm; LTE-Advanced: Heterogeneous Networks, Feb 2010 2012 Telesystem Innovations Inc. 13
Fractional Frequency Reuse 2012 Telesystem Innovations Inc. 14
LTE-A Radio Interface Technologies LTE-Advanced Maximum Bandwidth 100 MHz Carrier 1 Carrier 2 Carrier 3 Carrier 4 Carrier 5 Carrier Aggregation Peak Data Rate Joint transmission: DL/UL cooperative MIMO; Joint processing of received signals Spectral Efficiency Cell-edge Performance Coverage Coordinated Multiple Point Transmission and Reception (CoMP) 2012 Telesystem Innovations Inc. 15
Heterogeneous Networks Femto (Indoor) Coverage Relay RF Backhaul Pico-BS Spectral Efficiency Cell-edge Performance Coverage Relay Coverage Hole Cell-edge Performance Coverage C-RAN/RRH Spectral Efficiency Cell-edge Performance Coverage Enhanced ICIC (R10) Combined With Heterogeneous Networks 2012 Telesystem Innovations Inc. 16
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 2012 Telesystem Innovations Inc. 17
Telesystem Innovations frank@tsiwireless.com http://www.frankrayal.com 2012 Telesystem Innovations Inc. 18