1 / 21

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

dillon
Télécharger la présentation

OFDM(A) Competence Development – part III

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related