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OFDM(A) Competence Development – part III

OFDM(A) Competence Development – part III. Per Hjalmar Lehne , Frode Bøhagen, Telenor R&I R&I seminar, 23 January 2008, Fornebu, Norway Per-hjalmar.lehne@telenor.com Frode.bohagen@telenor.com. Outline. Part I: What is OFDM? Part II: Introducing multiple access: OFDMA, SC-FDMA

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OFDM(A) Competence Development – part III

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  1. OFDM(A) Competence Development – part III Per Hjalmar Lehne, Frode Bøhagen, Telenor R&I R&I seminar, 23 January 2008, Fornebu, Norway Per-hjalmar.lehne@telenor.com Frode.bohagen@telenor.com

  2. Outline • Part I: What is OFDM? • Part II: Introducing multiple access: OFDMA, SC-FDMA • Part III: Wireless standards based on OFDMA • Part IV: Radio planning of OFDMA OFDM Competence Development

  3. Mobile WiMAX 3GPP Evolved UTRA Basic OFDMA parameters Resource mappings and scheduling Multi-antenna support Comparison Other standards which use OFDM / OFDMA: 3GPP2 Ultra Mobile Broadband (UMB) WLAN, 802.11a, .11g, .11n Terrestrial Digital Broadcast: DVB-T, DVB-H Wireless standards OFDM Competence Development

  4. Mobile WiMAX R1– IEEE 802.16e • Based on the air-interface of IEEE 802.16e-2005 • Amendment to Fixed WiMAX IEEE 802.16-2004 • Adopted by ITU-R as member of the IMT-2000 family at RA-07 as “OFDMA TDD WMAN” • WiMAX Release 1 ready since 2006 • Scalable OFDMA. Bandwidth support: 5, 7, 8.75 and 10 MHz • Multi-antenna support (MIMO) • Expected peak data rates: • 72 Mb/s combined (TDD UL+DL); BW = 10 MHz, MIMO 2x2 • First working products in 2008 OFDM Competence Development

  5. Basic parameters for Mobile WiMAX OFDM Competence Development

  6. Resource mapping for Mobile WiMAX • Diversity permutations (Distributed mappings): • DL-FUSC – Fully Used Sub-Carrier • DL-PUSC, UL-PUSC – Partially Used Sub-Carrier • DL-TUSC – Tile Usage of Subcarriers • Contiguous permutation (Localized mapping): • Band AMC – Adaptive Modulation and Coding OFDM Competence Development

  7. Mobile WiMAX DL PUSC • Downlink Partially Used Sub-Carriers • Clusters of 14 contiguous SCs and two symbol intervals • Re-arranged to 6 groups • Permutation within each group to form sub-channels with 28 subcarriers (24 data + 8 pilot) • Obtains diversity gain over the whole bandwidth OFDM Competence Development

  8. Mobile WiMAX DL PUSC - explored OFDM Competence Development

  9. Mobile WiMAX UL PUSC • Uplink Partially Used Sub-Carrier • Tiles of 4 contiguous SCs and 3 symbol intervals • Re-arranged to 6 groups • Permutation within each group to form sub-channels with 28 subcarriers (24 data + 8 pilot) OFDM Competence Development

  10. Mobile WiMAX frame structure • Mobile WiMAX currently supports Time Division Duplex (TDD) • 802.16e also supports Frequency Division Duplex (FDD), Full- and half-duplex operation • All permutation schemes can be supported in each frame • DL PUSC is mandatory in first ”zone” Preamble PUSC (FCH, MAP) FUSC PUSC AMC TUSC PUSC AMC (Guard interval) DL UL Frame length: 48 OFDMA symbols/5 ms OFDM Competence Development

  11. 3GPP Evolved UTRA – ”LTE” • “Long Term Evolution” (LTE). “4G” technology from 3GPP. Standard more or less finalized in 2007 • Scalable OFDMA. Bandwidth support from 1.4 – 20 MHz • SC-FDMA on the uplink • Multi-antenna support (MIMO) • Expected data rate above 100 Mb/s DL, 50 Mb/s UL; BW = 20 MHz, 2x2 MIMO • Pilot tests in 2007/8, first products in 2009/10 OFDM Competence Development

  12. Basic parameters for E-UTRA OFDM Competence Development

  13. Resource mapping for E-UTRA • Time-frequency resources are organised in ”Resource blocks” spanning 12 SC x 7 symbol intervals (180 kHz x 0.5 ms) • Diversity permutation is by mapping ”virtual resource blocks” to ”physical resource blocks” • Uplink is always localized mapping using SC-FDMA OFDM Competence Development

  14. E-UTRA frame structures Frame structure type 1 (FDD) OFDM Competence Development

  15. Multi-antenna support • Beamforming • Multiple antennas are used to transmit or receive weighted signals to improve coverage and capacity • Space-Time Coding (STC) • Transmit diversity such as Alamouti coding to provide spatial diversity and reduce fading margin • Spatial Multiplexing (SM) - MIMO • Higher peak rates and increased throughput. Multiple streams are transmitted over multiple antennas. The receiver must also have multiple antennas to separate the different streams. • E-UTRA • ”Baseline” configuration: 2x2 (DL)1x2 (UL) • Mobile WiMAX • Minimum requirements, Wave II: 2x2 (DL), 1x2 (UL) • Reference signal (pilot) positions identify the different Tx antennas OFDM Competence Development

  16. E-UTRA vs. Mobile WiMAX • Sub-carrier distance and useful symbol time • E-UTRA more robust to Doppler • Cyclic prefix/guard interval • Mobile WiMAX more robust to multipath delays • Extended CP of E-UTRA an option for long delays • Bandwidth support • Basically same • Complexity • Similar • No clear winner when it comes to performance on the physical layer • Migration and co-existence • E-UTRA is taylored to ease co-existence with and migration from WCDMA/HSPA OFDM Competence Development

  17. Mobile WiMAX R2 – IEEE 802.16m • Completed Q4/07 ? • System profile R2 in 2008 ? • Bandwidth support: 5, 10, 20, 40 MHz • Peak data rates (requirements) • DL: > 350 Mb/s, 4x4 MIMO • UL: > 200 Mb/s, 2x4 MIMO • Average throughput per sector, BW = 20 MHz • DL: > 40 Mb/s • UL: > 12 Mb/s • Mobility support up to 350 km/h OFDM Competence Development

  18. Ultra Mobile Broadband (UMB) • Next generation mobile broadband access from 3GPP2 • Evolution from cdma2000 – EV-DO Rev. C • Published September 2007 • Bandwidths: 1.25 – 2.5 – 5 – 10 – 20 MHz • Number of subcarriers: 128, 256, 512, 1024, 2048 (FFT size) • Subcarrier spacing: 9.6 kHz • Useful symbol duraton: 104.17 ms • Cyclic prefix duration: 6.51, 13.02, 19.53, or 26.04 ms • Windowing guard interval: 3.26 ms • Modulation: QPSK, 8-PSK, 16-QAM, 64-QAM, hierarchical modulation OFDM Competence Development

  19. Wi-Fi, IEEE 802.11 • WLAN standards 802.11a, g and n uses OFDM • Multiple access is not OFDMA but CSMA (TDMA variant) • Channel bandwidth: 22 MHz • Number of subcarriers: 52 • Subcarrier spacing: 312.5 kHz • Useful symbol length: 3.2 ms • Guard interval (cyclic prefix): 0.8 ms • Modulation: BPSK, QPSK, 16-QAM, 64-QAM OFDM Competence Development

  20. Digital Terrestrial Broadcast, DVB-T/-H • Broadcast technologies using OFDM • No multiple access! • Channel bandwidths: 5, 6, 7, 8 MHz • Number of subcarriers (incl pilots): • 2K mode: 1705 (2048), • 4K mode: 3409 (4096) - only DVB-H • 8K mode: 6817 (8192) • Subcarrier spacing (8 MHz channel): • 4.464 kHz, 2.232 kHz, 1.116 kHz • Useful symbol length: • 224 ms, 448 ms, 896 ms • Guard interval (Cyclic prefix): • 1/32, 1/16, 1/8, 1/4 of useful symbol length: • Modulation: QPSK, 16-QAM, 64-QAM, hierarchical modulation OFDM Competence Development

  21. Summary - standards • Major future mobile broadband standards employ OFDMA • Mobile WiMAX, E-UTRA, UMB • Bandwidths are scalable • Flexible multi-user access • Multiple antennas (MIMO) supported • OFDM transmission is employed in several wireless standards • Fixed and nomadic wireless broadband: Wi-Fi, Fixed WiMAX • Digitial terrestrial broadcast: DVB-T, DVB-H OFDM Competence Development

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