March 2003 doc IEEE 802 15 03141 r

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Project: IEEE P 802. 15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [TI Physical Layer Proposal] Date Submitted: [03 March, 2003] Source: [Anuj Batra, Jaiganesh Balakrishnan, Anand Dabak, et al. ] Company [Texas Instruments] Address [12500 TI Blvd, MS 8649, Dallas, TX 75243] Voice: [214 -480 -4220], FAX: [972 -761 -6966], E-Mail: [batra@ti. com] Re: [This submission is in response to the IEEE P 802. 15 Alternate PHY Call for Proposal (doc. 02/372 r 8) that was issued on January 17, 2003. ] Abstract: [This document describes the TI physical layer proposal for IEEE 802. 15 TG 3 a. ] Purpose: [For discussion by IEEE 802. 15 TG 3 a. ] Notice: This document has been prepared to assist the IEEE P 802. 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 P 802. 15. Submission 1 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 TI Physical Layer Proposal: Time-Frequency Interleaved OFDM Anuj Batra, Jaiganesh Balakrishnan, Anand Dabak Ranjit Gharpurey, Paul Fontaine, Jerry Lin Jin-Meng Ho, Simon Lee, Michel Frechette Steven March, Hirohisa Yamaguchi Texas Instruments 12500 TI Blvd, MS 8649 Dallas, TX March 3, 2003 Submission 2 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Outline · Examine the trade-offs in the design of a UWB system: - Choice of operating bandwidth - Spreading gain vs. Pulse repetition frequency (PRF) · Overview of Time-Frequency Interleaved OFDM (TFI-OFDM) · Performance results for the TFI-OFDM system · Selected responses to the selection criteria · Advantages of the TFI-OFDM system · Summary Submission 3 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Trade-offs in Designing a UWB system: - Choice of Operating Bandwidth - Spreading Gain vs. PRF Submission 4 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 What Operating BW to Use? · Goals to keep in mind when selecting the operating BW: - Early time to market: want to enable UWB technology ASAP. CMOS friendly solutions: want solutions that can be integrated. Low cost: enable adoption of technology in portable CE devices. U-NII interference robustness: 802. 11 a is the incumbent device. World-wide compliance: one solution for the world. Antenna/filter design: want to be able to use off-the-shelf components. · We now examine the various trade-offs in choosing the operating BW. We want to select the operating BW in such a way as to achieve all of these goals. Submission 5 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Small Gains by Increasing BW (1) · Assume that the TX signal occupies the BW from f. L to f. U. - Assume that f. L is fixed at 3. 1 GHz. Vary upper frequency f. U between 4. 8 GHz and 10. 6 GHz. Assume that the transmit spectrum is flat over entire BW. TX power = -41. 25 d. Bm + 10 log 10(f. U – f. L). · 802. 15. 3 a has specified a free-space propagation model: - fg is the Geometric mean of lower/upper frequencies (10 -d. B points) - d is the UWB transmitter-receiver separation distance (assume d = 10 m) - c is the speed of light · Look at Received Power = TX Power - Path Loss, as a function of upper frequency. Submission 6 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Small Gains From Increasing BW (2) · Increasing the upper frequency to 7. 0 GHz (10. 5 GHz) gives at most a 2. 0 d. B (3. 0 d. B) advantage in total received power. · On the other hand, increasing the upper frequency, results in an increased noise figure: - For fu = 7. 0 GHz, by at least 1. 0 d. B. For fu = 10. 5 GHz, by at least 2. 0 d. B. · Result: using frequencies larger than 4. 8 GHz increases the overall link margin by at most 1. 0 d. B with the current RF technology, but at the cost of higher complexity and higher power consumption. · Conclusion: only incremental gains in the link budget can be realized by using frequencies above 4. 8 GHz. Submission 7 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Optimal Operating Bandwidth · Start with the frequency band from 3. 1 to 4. 8 GHz: - Simplifies the front-end design: LNA and mixers (CMOS friendly). Can use higher precision, lower sampling rate ADCs. Rake implementation, needed to collect multi-path, is easier. U-NII rejection is simplified. Quicker time to market! U-NII band: 802. 11 a Start with this band 3. 1 GHz Use this band in the future as technology improves 4. 8 GHz 5. 9 GHz 10. 6 GHz · As the RF technology improves, start using the higher band as well. Submission 8 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Spreading vs. PRF · A full-band system obtains its processing gain by spreading (high PRF) the signal across the entire UWB bandwidth. · A sub-band system obtains its processing gain by using a lower pulse repetition frequency (PRF) in each of the sub-bands. Coding UWB system parameters TFI-OFDM Sub-band Full-band Coding Spreading (High PRF) Low PRF Spreading Higher A/D speed, accurate timing Submission Lower rate ADC, low transmit power, single receive chain, relaxed timing Higher transmit power, multiple receiver chains 9 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Proposed System: TFI-OFDM Submission 10 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Time-Frequency Interleaved OFDM · Basic idea is to use OFDM over the entire BW: - Start with frequencies from 3168 MHz to 5280 MHz. · Total of 512 tones, where each tone has a bandwidth of 4. 125 MHz. · Use different subsets of frequency tones from one OFDM symbol to the next. · Equivalent to interleaving OFDM symbols across time and across frequency. Submission 11 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Simplified TFI-OFDM · The implementation of TFI-OFDM can be simplified by introducing a small guard interval (9. 5 ns) between the OFDM symbols. The simplified TFI-OFDM system can now be implemented using a single TX/RX chain, 128 -point IFFT/FFT, and low rate DACs/ADCs. Submission 12 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Alternative Views of TFI-OFDM · TFI-OFDM can be looked upon as a full-band OFDM system using a 512 -point IFFT/FFT. · TFI-OFDM can also be interpreted as a sub-band OFDM system using a 128 -point IFFT/FFT on each of the sub-channels. · Because TFI-OFDM can be viewed as both a full-band a sub- band approach, it inherits strengths from both types of systems. · We choose to view TFI-OFDM in terms of the second approach, because it leads to a much lower complexity solution and can be realized in today’s CMOS technology. Submission 13 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Details of the TFI-OFDM System *More details about the TFI-OFDM system can be found in the latest version of 03/142. Submission 14 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 TFI-OFDM: Example TX Architecture · Block diagram of an example TX architecture: · Architecture is similar to that of a conventional and proven OFDM system. Can leverage existing OFDM solutions for the development of the TFI-OFDM physical layer. · For a given superframe, the interleaving pattern is specified in the beacon by the PNC. The interleaving pattern is rotated across multiple superframes to mitigate multi-piconet interference. Submission 15 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 TFI-OFDM System Parameters · System parameters for rates specifically mentioned in selection criteria document: Info. Data Rate 110 Mbps 200 Mbps 480 Mbps Modulation/Constellation OFDM/QPSK FFT Size 128 128 Coding Rate (K=7) R = 11/32 R = 5/8 R = 3/4 Spreading Rate 2 2 1 Information Tones 50 50 100 Data Tones 100 100 Info. Length 242. 4 ns Cyclic Prefix 60. 6 ns Guard Interval 9. 5 ns Symbol Length 312. 5 ns Channel Bit Rate 640 Mbps Frequency Band 3168 – 4752 MHz Multi-path Tolerance 60. 6 ns Submission 16 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Simplified TX Analog Section · For rates up to 200 Mb/s, the input to the IFFT is forced to be conjugate symmetric (for spreading gains 2). Output of the IFFT is REAL. · The analog section of TX can be simplified when the input is real: Need to only implement the “I” portion of DAC and mixer. Only requires half the analog die size of a complete “I/Q” transmitter. · For rates > 200 Mb/s, need to implement full “I/Q” transmitter. Submission 17 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 OFDM Parameters · Transmit information using orthogonal carriers: Carriers are efficiently generated using a 128 -point IFFT. Use 100 tones for data (QPSK modulation). Use 12 tones for standard pilots. Use 10 tones for user-defined pilots (used to meet 500 MHz BW requirement). - Remaining 6 orthogonal tones are NULL (zero). - · Sub-carrier frequency spacing = 4. 125 MHz. · Cyclic prefix length = 32 samples (60. 6 ns). · Guard interval length = 5 samples (9. 5) – time used for switching. · Total OFDM symbol length = 165 samples (312. 5 ns). Submission 18 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Convolutional Encoder and Bit Interleaver · Assume a mother convolutional code of R = 1/3, K = 7. Having a single mother code simplifies the implementation. · Generator polynomial: g 0 = [1338], g 1 = [1458], g 2 = [1758]. · Higher rate codes are achieved by puncturing the mother code. · Bit interleaving is performed across bits within an OFDM symbol and across at most three OFDM symbols. - Exploits frequency diversity and randomizes any interference. Submission 19 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Channelization · The relationship between fc and channel number nch is · Initially, only the first 3 channels will be defined. CHNL_ID (nch) Center Frequency (fc) 1 3432 MHz 2 3960 MHz 3 4488 MHz · More channels can be added as RF technology improves. Submission 20 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 TFI-OFDM: PLCP Frame Format · PLCP frame format: · Rates supported: 55, 80, 110, 160, 200, 320, 480 Mb/s. Support for 55, 110, · · and 200 Mb/s is mandatory. Preamble length = 9. 38 ms. Burst preamble length = 4. 69 ms. For the sake of robustness, the PLCP header, MAC header, HCS, and tail bits are always sent at the information data rate of 55 Mb/s. PLCP header + MAC header + HCS + tail bits = 2. 19 ms. Maximum frame payload supported is 4095 bytes. Submission 21 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Link Budget and Receiver Sensitivity · Assumption: AWGN and 0 d. Bi gain at TX and RX antennas. Submission Parameter Value Information Data Rate 110 Mb/s 200 Mb/s 480 Mb/s Average TX Power -10. 3 d. Bm Total Path Loss 64. 2 d. B (@ 10 meters) 56. 2 d. B (@ 4 meters) 50. 2 d. B (@ 2 meters) Average RX Power -74. 5 d. Bm -66. 5 d. Bm -60. 5 d. Bm Noise Power Per Bit -93. 6 d. Bm -91. 0 d. Bm -87. 2 d. Bm RX Noise Figure 6. 6 d. B Total Noise Power -87. 0 d. Bm -84. 4 d. Bm -80. 6 d. Bm Required Eb/N 0 4. 0 d. B 4. 7 d. B 4. 9 d. B Implementation Loss 3. 0 d. B Link Margin 5. 5 d. B 10. 2 d. B 12. 2 d. B RX Sensitivity Level -80. 0 d. Bm -76. 7 d. Bm -72. 7 d. B 22 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 System Performance (1) · PER as a function of distance and information data rate in an AWGN and CM 2 environment*. * Results obtained using old channel model. Submission 23 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 System Performance (2) · PER as a function of distance and information data rate in an CM 3 and CM 4 environment*. * Results obtained using old channel model. Submission 24 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 System Performance (3) · The distance at which the TFI-OFDM system can achieve a PER of 8 % for a 90% link success probability is tabulated below **: Range* AWGN CM 1 CM 2 CM 3 CM 4 110 Mbps 19. 1 m N/A 9. 8 m 9. 7 m 8. 8 m 200 Mbps 13. 5 m N/A 6. 3 m 5. 8 m 5 m 480 Mbps 8. 7 m 2 m 2 m N/A * Includes losses due to front-end filtering, ADC degradation, multi-path degradation, channel estimation, carrier tracking, packet acquisition, etc. ** Results obtained using old channel model. Submission 25 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Simultaneously Operating Piconets · Assumptions: - Received signal is 6 d. B above sensitivity dref = 9. 55 meters · Single co-channel interferer separation distance as a function of the reference and interfering multipath channel environments. Test Link/Interferer CM 1 CM 2 CM 3 CM 4 CM 1 12. 6 m 13. 0 m 12. 3 m 12. 4 m CM 3 13. 0 m 12. 3 m 12. 2 m 12. 5 m CM 4 13. 8 m 12. 7 m 12. 2 m 12. 7 m Submission 26 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Signal Robustness/Coexistence · Assumption: received signal is 6 d. B above sensitivity. · Value listed below are the required distance or power level needed to obtain a PER 8% for a 1024 byte packet. Interferer Value IEEE 802. 11 b @ 2. 4 GHz dint = 0. 3 meter IEEE 802. 11 a @ 5. 3 GHz dint = 0. 3 meter Modulated interferer SIR -3. 8 d. B Tone interferer SIR -4. 8 d. B · Coexistence with 802. 11 a/b and Bluetooth is relatively straightforward because these bands are completely avoided. Submission 27 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 PHY-SAP Throughput · Assumptions: - MPDU (MAC frame body + FCS) length is 1024 bytes. - SIFS = 10 ms. - MIFS = 2 ms. Number of frames Throughput @ 110 Mb/s Throughput @ 200 Mb/s Throughput @ 480 Mb/s 1 85. 1 Mb/s 130. 4 Mb/s 211. 4 Mb/s 5 95. 2 Mb/s 155. 6 Mb/s 286. 4 Mb/s · Assumptions: - MPDU (MAC frame body + FCS) length is 4024 bytes. Number of frames Throughput @ 110 Mb/s Throughput @ 200 Mb/s Throughput @ 480 Mb/s 1 102. 3 Mb/s 175. 9 Mb/s 362. 4 Mb/s 5 105. 7 Mb/s 186. 3 Mb/s 409. 2 Mb/s Submission 28 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Complexity · Unit manufacturing cost (selected information): - Process: CMOS 90 nm technology node in 2005. Analog section: die size of 2. 7 mm 2. Digital section: 295 K gates, die size of 1. 5 mm 2. · Power consumption: Rate TX RX Deep Sleep 110 Mb/s 93 m. W 142 m. W 15 m. W 200 Mb/s 93 m. W 156 m. W 15 m. W · Manufacturability: Leveraging standard CMOS technology results in a straightforward development effort. OFDM solutions are mature and have been demonstrated in 802. 11 a and 802. 11 g solutions. · Time to market: the earliest a complete CMOS PHY solution would be ready for integration is 2005. · Size: Solutions for PC card, compact flash, memory stick, SD memory in 2005. Submission 29 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 MAC Enhancements · Add a time-frequency interleaving information element (TFI IE) to the beacon: - TFI IE contains parameters for synchronizing DEVs using TFI-OFDM PHY. IE payload contains Interleaving Sequence (IS) and Rotation Sequence (RS) parameters. - IS field specifies the current pattern for interleaving over the channels. RS field specifies the current rotation pattern for the interleaving sequences. · PNC updates the IS parameter in the beacon for each superframe according to the RS parameter. - DEVs that miss the beacon can determine the IS based on the definition of the RS in the last beacon received. · PNC may change the RS parameter by applying the piconet parameter change procedure specified in the IEEE 802. 15. 3 draft standard. - Submission Reuse “New Channel Index” as “New Channel Index/RS Number”. 30 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 MAC Controlled Rules for Interleaving · Piconet #1: - Ex: RS_2 = {IS_2, IS_3, IS_1, IS_3, IS_2, IS_1, Repeat} Ex: IS_1 = {Chan_2, Chan_1, Chan_3, Chan_1, Chan_2, Chan_3, Repeat} · Piconet #2: Submission Ex: RS_2 = {IS_1, IS_3, IS_2, IS_1, IS_2, IS_3, Repeat} 31 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 TFI-OFDM Advantages (1) · Suitable for CMOS implementation. · Only one transmit and one receive chain. · Antenna and pre-select filter are easier to design (can possibly use off-the-shelf components). Early time to market! · Low cost, low power, and CMOS integrated solution leads to: Early market adoption! Submission 32 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 TFI-OFDM Advantages (2) · Excellent robustness to ISM and U-NII interference. · Excellent robustness to narrowband interference. · Ability to comply with world-wide regulations: - Channels and tones can be dynamically turned on/off to comply with changing regulations. · Coexistence with current and future systems: - Channels and tones can be dynamically turned on/off for enhanced coexistence with the other devices. · Scalability: - More channels can be added as the RF technology improves. - Digital section complexity/power scales with improvements in technology nodes (Moore’s Law). Submission 33 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Summary · The proposed system is specifically designed to be a low power, low complexity CMOS solution. · Expected range for 110 Mb/s: 19. 1 meters in AWGN, and nearly 10 meters in multipath environments. · Expected power consumption for 110 Mb/s: 93 m. W (TX), 142 m. W (RX), 15 m. W (deep sleep) · TFI-OFDM is coexistence friendly and complies with world-wide regulations. · PHY solution are expected to be ready for integration in 2005. · TFI-OFDM offers the best trade-off between the various system parameters. Submission 34 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Backup slides Submission 35 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Signal Acquisition · Preamble was designed to be robust and work at 3 d. B below sensitivity for 55 Mbps. Channel Environment Pm @ 110 Mb/s Pf Acquisition Time AWGN < 2 10 -5 7. 2 10 -4 < 4. 69 ms CM 1 < 2 10 -5 7. 2 10 -4 < 4. 69 ms CM 2 < 2 10 -5 7. 2 10 -4 < 4. 69 ms CM 3 < 2 10 -5 7. 2 10 -4 < 4. 69 ms CM 4 < 2 10 -5 7. 2 10 -4 < 4. 69 ms · The start of a valid OFDM transmission at a receiver sensitivity level -83 d. Bm shall cause CCA to indicate busy with a prob. > 90% in 4. 69 ms. Submission 36 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Is Cyclic Prefix (CP) Sufficient? · For a data rate of 110 Mb/s, studied effect of CP length on performance. · Curves were averaged over 100 realizations of CM 3. · For a CP length of 60 ns, the average loss in collected multipath energy is approx. 0. 1 d. B. · Inter-carrier interference (ICI) due to multi-path outside the CP is approximately 18. 5 d. B below the signal. Submission 37 Anuj Batra et al. , Texas Instruments

March 2003 doc. : IEEE 802. 15 -03/141 r 0 Peak-to-Average Ratio (PAR) for TFI-OFDM · Average TX Power = – 9. 5 d. Bm (this value includes pilot tones) · PAR of 9 d. B results in: - 0. 04 % packets being clipped at TX DAC. - Loss of less than 0. 1 d. B in AWGN. - Loss of less than 0. 1 d. B in multipath. · Peak TX power 0 d. Bm. · Implication: TX can be built completely in CMOS. Submission 38 Anuj Batra et al. , Texas Instruments