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Multi-band OFDM Physical Layer Proposal Update

This document describes the multi-band OFDM proposal for IEEE 802.15 TG3a, focusing on spectrum flexibility, reduced power consumption, and improved energy collection under severe multipath conditions.

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Multi-band OFDM Physical Layer Proposal Update

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  1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Multi-band OFDM Physical Layer Proposal Update] Date Submitted: [10 November, 2003] Source: [Presenter 1:Roberto Aiello] Company [Staccato Communications] [Presenter 2:Anand Dabak] Company [Texas Instruments] [see page 2,3 for the complete list of company names, authors, and supporters] Address [12500 TI Blvd, MS 8649, Dallas, TX 75243] Voice:[214-480-4389], FAX: [972-761-6966], E-Mail:[dabak@ti.com] Re: [This submission is in response to the IEEE P802.15 Alternate PHY Call for Proposal (doc. 02/372r8) that was issued on January 17, 2003.] Abstract: [This document describes the Multi-band OFDM proposal for IEEE 802.15 TG3a.] Purpose: [For discussion by IEEE 802.15 TG3a.] Notice: This document has been prepared to assist the IEEE P802.15. It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein. Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15. A. Dabak, TI, R. Aiello, Staccato, et al.

  2. This contribution is a technical update authored by*: Texas Instrument [03/141]: Batra Femto Devices [03/101]: Cheah FOCUS Enhancements [03/103]: Boehlke General Atomics [03/105]: Askar Institute for Infocomm Research [03/107]: Chin Intel [03/109]: Brabenac Mitsubishi Electric [03/111]: Molisch Panasonic [03/121]: Mo Philips [03/125]: Kerry Samsung Advanced Institute of Technology [03/135]: Kwon Samsung Electronics [03/133]: Park SONY [03/137]: Fujita Staccato Communications [03/099]: Aiello ST Microelectronics [03/139]: Roberts Time Domain / Alereon [03/143]: Kelly University of Minnesota [03/147]: Tewfik Wisair [03/151]: Shor * For a complete list of authors, please see page 3. A. Dabak, TI, R. Aiello, Staccato, et al.

  3. Authorsfrom 17 affiliated companies/organizations Femto Devices: J. Cheah FOCUS Enhancements: K. Boehlke General Atomics:N. Askar, S. Lin, D. Furuno, D. Peters, G. Rogerson, M. Walker Institute for Infocomm Research: F. Chin, Madhukumar, X. Peng, Sivanand Intel:J. Foerster, V. Somayazulu, S. Roy, E. Green, K. Tinsley, C. Brabenac, D. Leeper, M. Ho Mitsubishi Electric:A. F. Molisch, Y.-P. Nakache, P. Orlik, J. Zhang Panasonic: S. Mo Philips: C. Razzell, D. Birru, B. Redman-White, S. Kerry Samsung Advanced Institute of Technology:D. H. Kwon, Y. S. Kim Samsung Electronics: M. Park SONY:E. Fujita, K. Watanabe, K. Tanaka, M. Suzuki, S. Saito, J. Iwasaki, B. Huang Staccato Communications:R. Aiello, T. Larsson, D. Meacham, L. Mucke, N. Kumar, J. Ellis ST Microelectronics:D. Hélal, P. Rouzet, R. Cattenoz, C. Cattaneo, L. Rouault, N. Rinaldi,, L. Blazevic, C. Devaucelle, L. Smaïni, S. Chaillou Texas Instruments:A. Batra, J. Balakrishnan, A. Dabak, R. Gharpurey, J. Lin, P. Fontaine, J.-M. Ho, S. Lee, M. Frechette, S. March, H. Yamaguchi Time Domain / Alereon: J. Kelly, M. Pendergrass University of Minnesota: A.H. Tewfik, E. Saberinia Wisair:G. Shor, Y. Knobel, D. Yaish, S. Goldenberg, A. Krause, E. Wineberger, R. Zack, B. Blumer, Z. Rubin, D. Meshulam, A. Freund A. Dabak, TI, R. Aiello, Staccato, et al.

  4. In addition, the following 19 affiliated companies support this proposal: Adamya Computing Technologies: S.Shetty Broadcom: J. Karaoguz Fujitsu Microelectronics America, Inc: A. Agrawal Furaxa: E. Goldberg Hewlett Packard: M. Fidler Infineon: Y. Rashi JAALAA: A. Anandakumar Microsoft: A. Hassan NEC Electronics: T. Saito Nokia: P. A. Ranta Realtek Semiconductor Corp: T. Chou RFDomus: A. Mantovani SiWorks: R. Bertschmann SVC Wireless: A. Yang TDK: P. Carson TRDA: M. Tanahashi tZero: O. Unsal UWB Wireless: R. Caiming Qui Wisme: N. Y. Lee A. Dabak, TI, R. Aiello, Staccato, et al.

  5. Why did 10 Companies Propose Multi-Band Solutions in March 2003 ? Some of the reasons include: • Spectrum Flexibility / Agility • Regulatory regimes may lack large contiguous spectrum allocations • Spectrum agility may ease coexistence with existing services • Energy collected per RAKE finger scales with longer pulse widths used • Fewer RAKE fingers • Reduced bandwidth after down-conversion mixer reduces power consumption and linearity requirements of receiver • Fully digital solution for the signal processing is more feasible than a single band solution for the same occupied bandwidth • Transmitter pulse shaping made easier • Longer pulses easier to synthesize & less distorted by IC package & antenna properties • Have the ability to utilize an FDMA mode for severe near-far scenarios A. Dabak, TI, R. Aiello, Staccato, et al.

  6. Most of the Multi-Band Proposals in March 03’ used Pulses, What Happened ? • Energy collection under severe multipath (CM3, CM4) required improvement • We needed a computationally efficient method of multipath combining • Parallel receivers? Infinite RAKE? OFDM? • OFDM in each sub-band was selected as a successor to the pulsed multi-band approaches A. Dabak, TI, R. Aiello, Staccato, et al.

  7. Why are 37+ Companies Now Supporting the Multi-band OFDM Approach ? • Multi-band OFDM kept the unique Multi-Band benefits and solved the energy collection problem very elegantly • Feasibility studies of FFT and Viterbi cores showed encouraging numbers for gate-count and power consumption • Multi-band OFDM suitable for CMOS implementation (all components) • Antenna and pre-select filter are easier to design (can possibly use off-the-shelf components) • Low cost + low power + CMOS integrated solution = early market adoption • Scalability: • Digital section complexity/power scales with improvements in technology nodes (Moore’s Law). • Analog section complexity/power scales slowly with technology node • Much more can be said in detail about the Multi-band OFDM PHY performance, but first we should review our proposal… A. Dabak, TI, R. Aiello, Staccato, et al.

  8. Overview of OFDM • OFDM was invented more than 40 years ago • Adopted by numerous standards effort: • Asymmetric Digital Subscriber Line (ADSL) services. • IEEE 802.11a/g; IEEE 802.16a • Digital Audio Broadcast (DAB); Home Plug • Digital Terrestrial Television Broadcast: DVD in Europe, ISDB in Japan • OFDM is also being considered for 4G, IEEE 802.11n and 802.20 • OFDM is spectrally efficient. • IFFT/FFT operation ensures that sub-carriers do not interfere with each other • OFDM has an inherent robustness against narrowband interference. • Narrowband interference will affect at most a couple of tones. • Information from the affected tones can be erased and recovered via the forward error correction (FEC) codes • OFDM has excellent robustness in multi-path environments. • Cyclic prefix preserves orthogonality between sub-carriers. • Cyclic prefix allows the receiver to capture multi-path energy more efficiently A. Dabak, TI, R. Aiello, Staccato, et al.

  9. Overview of Multi-Band OFDM • Basic idea: divide spectrum into several 528 MHz bands • Information is transmitted using OFDM modulation on each band • OFDM carriers are efficiently generated using an 128-point IFFT/FFT • Internal precision is reduced by limiting the constellation size to QPSK • Information bits are interleaved across all bands to exploit frequency diversity and provide robustness against multi-path and interference • 60.6 ns prefix provides robustness against multi-path even in the worst channel environments • 9.5 ns guard interval provides sufficient time for switching between bands • Solution is very scalable and flexible • Data rates, power scaling, frequency scaling, complexity scaling *See latest version of 03/268 for more details about the Multi-Band OFDM system A. Dabak, TI, R. Aiello, Staccato, et al.

  10. Band Plan • Group the 528 MHz bands into 4 distinct groups. • Group A: Intended for 1st generation devices (3.1 – 4.9 GHz). • Group B: Reserved for future use (4.9 – 6.0 GHz). • Group C: Intended for devices with improved SOP performance (6.0 – 8.1 GHz). • Group D: Reserved for future use (8.1 – 10.6 GHz). • Use of Group A is mandatory, while use of Group A+C is optional. A. Dabak, TI, R. Aiello, Staccato, et al.

  11. FCC Compliance of Multi-band OFDM Presenter: Anand Dabak A. Dabak, TI, R. Aiello, Staccato, et al.

  12. Interference and the FCC (1) • In 03/153r9 (July 2003), XSI stated: “The issue today is NOT whether or not there is more or less interference, the issue is, what are the rules” • XSI/Motorola filed a petition with the FCC for declaratory ruling immediately after the San Francisco meeting: • Q: Should a multi-band OFDM waveform be transmitted at a lower power than other UWB systems? • The FCC response (full response in back-up slides): • FCC’s concern is not with interpretations of the rules, but rather with interference. • “We urge that IEEE perform technical analyses to ensure that any UWB standard it develops will not cause levels of interference beyond that already anticipated by the rules.” A. Dabak, TI, R. Aiello, Staccato, et al.

  13. Interference and the FCC (2) • Interference: • We have identified several systems that need to be considered by any UWB transmitter. • Most of these systems are out of band (OOB) and require adoption of an appropriate spectral mask to ensure appropriate level of protection. • Several simulation studies completed looking at impact of MB-OFDM waveform on various FEC schemes often employed in wideband FSS systems. • Several (measurement based) experiments are being conducted to determine impact to real systems. • MB-OFDM does not cause any more interference than already anticipated by current FCC rules. • FCC compliance: Contrary to XSI’s claims, the multi-band OFDM system is FCC compliant and should not have to reduce its transmit power. A. Dabak, TI, R. Aiello, Staccato, et al.

  14. Study of Potential Victim Receivers • Most US government and commercial systems are out-of-band (OOB): • For OOB systems, victim receiver performance is expected to be the same for MBOK & MB-OFDM type UWB interference. • MB-OFDM has a slight advantage due to better OOB rejection capabilities. • No impact expected on CW & Pulsed Altimeter systems due to high tolerable UWB TX power limits (NTIA Report: +14 dBm/MHz). • Analog FSS systems are quickly being replaced by digital FSS systems. • In 1995, there were 2 million analog FSS systems. In 2002, only 500K. • Digital FSS systems are more robust to interference. A. Dabak, TI, R. Aiello, Staccato, et al.

  15. FSS Simulation results • 35 MSPS, rate 7/8 coding, no interleaving, Iuwb/N = -6 dB [XSI filing to FCC for typical operating scenarios, Sept. 2003] Very little difference between UWB radios under realistic scenarios [Note: SINR=C/(N+Is+Iuwb), Is=satellite intra-system interference] A. Dabak, TI, R. Aiello, Staccato, et al.

  16. Interference into FSS band • Interference and coexistence studies depend on a number of factors: • Application dependent variations: expected minimum separation distance between UWB emitter and victim receiver under realistic usage models, probability of this minimum separation distance seen in reality, pervasiveness of victim receiver • Implementation variations: antenna gain response, available link margin, FEC and other signal processing techniques adopted to mitigate noise and interference • Other interference sources: intra-system interference sources, noise floor of device • Allowed interference margins: minimum criteria for interference level and impact on probability of outage, built-in margin for external interference sources (all systems must expect some level of interference) • Potential interference caused by multi-band OFDM is lower than that generated by impulse radios, which are allowed under FCC rules. A. Dabak, TI, R. Aiello, Staccato, et al.

  17. Interference to Out-of-band Systems • Many of the government systems (FAA, DOD) and commercial systems (GPS, PCS) are out of band (OOB) for the proposed UWB systems. • The OOB rejection capability for UWB systems is important when analyzing interference to these systems. • Since the multi-band OFDM system employs a narrower bandwidth than MBOK, it can achieve better OOB rejection: • OFDM has an inherent steep roll-off at the band edges due to modulating narrow tones (~4 MHz) relative to the occupied bandwidth (528 MHz). • To achieve similar roll-off, an MBOK system would require sharp (higher-order) filters, which can be expensive in terms of die area and insertion loss. • Hence, interference into out of band FAA, GPS, and PCS systems can be much less from MB-OFDM systems than from MBOK systems. A. Dabak, TI, R. Aiello, Staccato, et al.

  18. Future In-band Interference Mitigation Techniques FCC Chairman Michael PowellKey Steps toward Spectrum Reform* • International regulatory agencies are supportive of frequency agile solutions to help protect different services in different locations • Recent ITU meeting shows uncertainties still exist around international regulations • Multi-band OFDM is an efficient method for enabling frequency agility • There is a substantial amount of “white space” out there that is not being used by anybody. • A software-defined radio may allow licensees to dynamically “rent” certain spectrum bands when they are not in use by other licensees. * “Broadband Migration III: New Directions in Wireless Policy” University of Colorado at Boulder, Oct 30, 2002 A. Dabak, TI, R. Aiello, Staccato, et al.

  19. HomePlug Power Line Spectral Mask -- A Precedent for Low-Cost “Sculpting” via OFDM Technology Source: HomePlug Alliance, HomePlug & ARRL Joint Test Report, January 24, 2001 30dB Notches Protect Amateur Radio Frequency, MHz OFDM enables simple interference reduction techniques A. Dabak, TI, R. Aiello, Staccato, et al.

  20. Conclusions and Summary • Conclusions about FSS: • Both multi-band OFDM and WGN waveforms are less harmful than impulse radios, which are allowed under the FCC. • Contrary to XSI’s claims, multi-band OFDM is FCC compliant and should not have to reduce its transmit power. • Summary: • The multi-band OFDM proponents are committed to ensuring that no harmful interference is caused to potential victim receivers. • Both simulations and real experimental testing will continue in order to determine if anything in the current proposal needs to be changed to help mitigate potential interference: • This should be the case for ANY draft proposal adopted by the IEEE. • The combination of multi-banding and OFDM provides a unique capability to tightly control OOB emissions as well as enables spectrum flexibility to protect future systems and differences in international allocations. A. Dabak, TI, R. Aiello, Staccato, et al.

  21. Comparison Between theMulti-band OFDM and MBOK Proposals Presenter: Anand Dabak A. Dabak, TI, R. Aiello, Staccato, et al.

  22. “Apples to Apples” Comparison • Similar frequency bands; MB-OFDM 3.1-4.9 GHz, MBOK 3.15-5.15 GHz • Compared multi-band OFDM versus MBOK with respect to: • Performance and range in multi-path channel environments. • Robustness to interference from a single tone jammer. • Analog and RF implementation considerations. • ADC precision requirements. • Digital complexity. • Comparison based upon widely available information for MBOK system. • Digital architectures for MBOK/DS-CDMA have been selected for the comparison. • Expected to provide better performance over analog implementation [slide 8 of 03/0334r2] A. Dabak, TI, R. Aiello, Staccato, et al.

  23. Architecture 1 (**) Chip matched filter (150 fingers) ADC 2.736 GHz, 1 bit ADC MBOK demodulator (I, Q) FEC decoding ADC 2.736 GHz, 1 bit ADC Channel estimates Architecture 2 Chip matched filter (16 fingers) ADC 2.736 GHz, No ADC quantization MBOK demodulator (I, Q) FEC decoding ADC 2.736 GHz, No ADC quantization Channel estimates MBOK simulation environment • Receiver architectures used for MBOK simulations: **: Analogous to the architecture proposed by ParthusCeva in 03/0334r3, ParthusCeva employs a single 1 bit ADC at 5.472 GHz A. Dabak, TI, R. Aiello, Staccato, et al.

  24. MBOK simulation parameters (Architecture 1) • Degradations from packet detection, time/carrier tracking, front end filtering, not included in simulations ***: 150 fingers at I, Q complex are equivalent to 300 fingers in 03/334r3 [1]: 03/0334r3 A. Dabak, TI, R. Aiello, Staccato, et al.

  25. MB-OFDM simulation parameters • Time tracking, carrier phase tracking, front end filtering, ADC quantization losses included in the simulations A. Dabak, TI, R. Aiello, Staccato, et al.

  26. Simulation parameters comparison • Degradations: • MBOK simulations results are optimistic. • Calibrated M-BOK performance (see backup slide 62). A. Dabak, TI, R. Aiello, Staccato, et al.

  27. Multi-path Performance Comparison A. Dabak, TI, R. Aiello, Staccato, et al.

  28. MB-OFDM outperforms MBOK by about 1 dB. Performance for 112/110 Mbps • Multi-band OFDM outperforms MBOK with 150 finger RAKE by about 1 dB in multi-path channel environment (CM3). A. Dabak, TI, R. Aiello, Staccato, et al.

  29. MB-OFDM outperforms MBOK by ~5 dB Performance for 224/200 Mbps • Multi-band OFDM outperforms MBOK with 150 finger RAKE by about 5 dB in multi-path channel environment (CM3). A. Dabak, TI, R. Aiello, Staccato, et al.

  30. Error Floor for MBOK • The MBOK system hits an error floor in multi-path channel environments for data rates of 200 Mbps (CM3) and 448 Mbps (CM2). Error floor for MBOK (does not reach 10-5) A. Dabak, TI, R. Aiello, Staccato, et al.

  31. Performance: 16 finger RAKE • MBOK performance improves marginally with 16 finger RAKE & no ADC quantization. But, • 112/114 Mbps MBOK is ~1.5 dB worse than 110 Mbps MB-OFDM. • 224/448 Mbps MBOK is about 4 to 6 dB worse than 200/480 Mbps MB-OFDM. • 200 Mbps MBOK hits an error floor. A. Dabak, TI, R. Aiello, Staccato, et al.

  32. Range Comparisons A. Dabak, TI, R. Aiello, Staccato, et al.

  33. Range in AWGN • Transmitter backoff, propagation loss calculations given in backup. • Multi-band OFDM has better range than MBOK in an AWGN environment. • 20 m (110 Mbps MB-OFDM) versus 16.8 m (112 Mbps MBOK) • 14 m (200 Mbps MB-OFDM) versus 12.6 m (224 Mbps MBOK) • 7.8 m (480 Mbps MB-OFDM) versus 6.8 m (448 Mbps MBOK) 480 Mbps 448 Mbps 224 Mbps 200 Mbps 200 Mbps 110 Mbps 114 Mbps 112 Mbps A. Dabak, TI, R. Aiello, Staccato, et al.

  34. Range in Multi-path • Multi-band OFDM has significantly better range than the MBOK system. • 11.6 m (110 Mbps MB-OFDM) versus 9.4 m (112 Mbps MBOK) • 6.8 m (200 Mbps MB-OFDM) versus 3.9 m (224 Mbps MBOK) • 2.6 m (480 Mbps MB-OFDM) versus 1.2 m (448 Mbps MBOK) 480 Mbps 448 Mbps 200 Mbps 224 Mbps 200 Mbps 110 Mbps 112 Mbps 114 Mbps A. Dabak, TI, R. Aiello, Staccato, et al.

  35. Single Tone Interferer A. Dabak, TI, R. Aiello, Staccato, et al.

  36. Architecture 2 Architecture 1 Single Tone Interferer Simulation Results • Assumption: receiver operates 6 dB above sensitivity (15.3a criterion) • For MBOK need SIR = 4 dB for architecture #1 and SIR = –1 dB for architecture #2. A. Dabak, TI, R. Aiello, Staccato, et al.

  37. Single Tone Interferer Comparison • For a fair comparison between two systems, we assume there is no analog filter notches for either system. • MB-OFDM results in backup [03-268r1P802-15_TG3a-Multi-band-CFP-Document.doc] • Multi-band OFDM system out performs MBOK architecture #2 by 7 dB, and MBOK architecture #1 by 12 dB. • May be possible to use DSP techniques for MBOK to improve its performance, however the complexity of MBOK receiver will then increase. A. Dabak, TI, R. Aiello, Staccato, et al.

  38. ADC Requirements for an MBOK System A. Dabak, TI, R. Aiello, Staccato, et al.

  39. ADC requirements for MBOK architecture 2 • Multi-path simulations: CM3 for 224 Mbps, CM2 for 448 Mbps • 3 bits required for 224 Mbps, 4 bits required for 448 Mbps MBOK architecture 2, 448 Mbps MBOK architecture 2, 224 Mbps A. Dabak, TI, R. Aiello, Staccato, et al.

  40. ADC Requirement Comparison • Multi-band OFDM requires a lower sampling rate ADC than the MBOK system. • For rates less than 224 Mbps: • MB-OFDM requires an ADC running at 528 MHz with 4 bits precision. • MBOK requires an ADC running at 2736 MHz with 3 bits precision. • MBOK may employ chip rate sampling, but performance will be worse. • For rates greater than 224 Mbps: • MB-OFDM requires an ADC running at 528 MHz with 5 bits precision. • MBOK requires an ADC running at 2736 MHz with 4 bits precision. • MBOK may employ chip rate sampling, but performance will be worse. • The ADC requirements for the multi-band OFDM system is simpler than that required for the MBOK system architecture 2. A. Dabak, TI, R. Aiello, Staccato, et al.

  41. Analog/RF Implementation Comparison A. Dabak, TI, R. Aiello, Staccato, et al.

  42. 1.368 GHz complex samples* Chip matched filter (300 fingers) Filter LNA 5.472 GHz 1 bit ADC Is RF sampling feasible for MBOK ? • Proposed RF sampling architecture for MBOK in 03/334r3. • Two crucial issues: • Out of band interference rejection IEEE 802.11a. • RF gain feasibility. A. Dabak, TI, R. Aiello, Staccato, et al.

  43. 802.11(a) MBOK UWB 3.1 GHz 5.1 GHz 6.5 GHz 10.6 GHz 1.368 GHz complex samples\ Chip matched filter (300 fingers) Filter (offchip) Filter (offchip) LNA 5.472 GHz 1 bit ADC IEEE 802.11a rejection • For an IEEE 802.11a device to operate within 1 meter of UWB, the IEEE 802.11a rejection required is a total of ~60 dB. • With an off-chip filter, one can achieve ~ 30 dB of rejection. Still need another ~ 30 dB of rejection. • Only other possibility: Put another off-chipfilter after LNA. • This implies: • Higher bill of material, special components: Higher cost. • Increased off-chip external components: Cannot have an integrated solution. A. Dabak, TI, R. Aiello, Staccato, et al.

  44. Block not shown in 03/334r3, but will be needed in practice GA ~ 45 dB gain, center freq : 4.1 GHz bandwidth: 1.6 GHz Filter (2 dB loss) LNA ~ 15 dB gain 5.472 GHz 1 bit ADC 21 mV Voltage has to be in the order of ~ 20 mV RF gain feasibility for MBOK • The sensitivity for 110 Mbps MBOK is -80 dBm • Even for a 1 bit ADC, an RF sampling architecture for MBOK will require gain amplifiers with a total gain of 60 dB at an RF center frequency of 4.1 GHz and bandwidth of 1.6 GHz. • Such wideband, high gain amplifiers at RF frequencies are very difficult to implement in practice. • Oscillations: Stability problems • Yield: Time to market • Hence it may be very risky in practice to implement the RF sampling architecture proposed in 03/334r3 A. Dabak, TI, R. Aiello, Staccato, et al.

  45. 750 MHz bandwidth p cos ( 2 ) f t c Pre-Select I Filter LPF GA/ VGA ADC 2.736 GHz, 1/3/4 bit ADC LNA Q LPF GA/ VGA ADC 2.736 GHz, 1/3/4 bit ADC p sin ( 2 ) f t c Mixer based architecture for MBOK System • A mixer-based architecture for front end RF is feasible for the MBOK system. • Need a 750 MHz wide low pass filter with sharp cutoff: MB-OFDM needs 250 MHz filter • Need a broad band GA/VGA (750 MHz) for MBOK: MB-OFDM needs 250 MHz wide VGA • Need 1 bit ADC at 2736 MHz for architecture 1 and 3-4 bit ADC at 2736 MHz for architecture 2: MB-OFDM needs 528 MHz 4-5 bits ADC. • MB-OFDM needs to generate multiple frequencies while MBOK needs to generate a single frequency. A. Dabak, TI, R. Aiello, Staccato, et al.

  46. Criteria MB-OFDM Advantage Neutral MBOK Advantage Front-end Filter/LNA/Mixer Frequency Synthesis Low-pass Filter VGA ADC Complexity ADC Feasibility Comparison of RF/Analog Complexity • Qualitative comparison of RF/Analog complexity between MB-OFDM and MBOK. (1) Architecture 1: 1 bit ADC Quantization. (2) Architecture 2: 3-4 bit ADC Quantization. A. Dabak, TI, R. Aiello, Staccato, et al.

  47. Digital Complexity Comparison A. Dabak, TI, R. Aiello, Staccato, et al.

  48. Preamble detection/ synchronization Channel estimation 1.368 GHz complex Chip matched Filter (150/16 fingers) MBOK demodulator (I, Q) Carrier phase correction FEC decoding 2.736 GHz complex samples in Carrier tracking Time tracking Digital RX Block Diagram for MBOK • Assumption: 130 nm technology at 85.5 MHz (per 03/334r3-03/447r0). • We estimated the complexity for the major blocks (shaded blocks) of the MBOK system. The implementation complexity of shaded blocks was calculated. The implementation complexity for other blocks was not taken into account A. Dabak, TI, R. Aiello, Staccato, et al.

  49. Chip Matched Filter (CMF) Complexity • Assumption: 150 fingers with a 1-bit ADC. • CMF needs about 225,000 gates (85.5 MHz clock) • In 03/334r3, the estimated gate is 75,000 (85.5 MHz). • Difference occurs because 03/334r3 did not take into account that both I & Q outputs (224 Mbps mode is QPSK) are needed from the CMF output. • In the latest document [03-0447] it is estimated as 49,400 (171 MHz clock) for real CMF and 90,200 (171 MHz clock) for complex CMF • For a fair comparison should use the same clock frequency. A. Dabak, TI, R. Aiello, Staccato, et al.

  50. Complexity for MBOK Architecture #1 • Assumption: 130 nm, 85.5 MHz clock. • Backup slides contains calculations for MBOK decoder and synch block. • To make a fair comparison with MB-OFDM system, we need to adjust to clock of MBOK to 132 MHz: • MBOK system requires ~400K gates (@132 MHz). • Multi-band OFDM system needs 295K gates (@132 MHz) [03-0343]. • MBOK system requires 35% more baseband complexity when compared to the multi-band OFDM system. A. Dabak, TI, R. Aiello, Staccato, et al.

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