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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [ High Rate Alt-PHY with shorter backward compatible mapping sequences ] Date Submitted: [25 July, 2004] Source: [Francois Chin] Company: [Institute for Infocomm Research, Singapore]

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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

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  1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [High Rate Alt-PHY with shorter backward compatible mapping sequences] Date Submitted: [25 July, 2004] Source: [Francois Chin] Company: [Institute for Infocomm Research, Singapore] Address: [21 Heng Mui Keng Terrace, Singapore 119613] Voice: [65-68745684] FAX: [65-67768109] E-Mail: [chinfrancois@i2r.a-star.edu.sg] Re: [Response to the call for proposal of IEEE 802.15.4b, Doc Number: 15-04-0239-00-004b] Abstract: [This presentation represents Institute for Infocomm Research (I2R)’s proposal for the P802.15.4b PHY standard, emphasizing the need for a high rate alternative PHY for low cost system having excellent sensitivity and long battery life.] Purpose: [Proposal to IEEE 802.15.4b Task Group] 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. Francois Chin, Institute for Infocomm Research (I2R)

  2. Proposal • A set of shorter sequences for backward compatible Symbol-to-Chip mapping that allows the current 802.15.4 2.4GHz PHY modulation scheme to be used on the low bands 868/915 MHz: • Channel separation = 2MHz • The main-lobe bandwidth = 1.5MHz • Chip Rate = 1 Mcps • Data rate = 250kbps or 500kbps • Chips / 4-bit Symbol = 16 or 8 Francois Chin, Institute for Infocomm Research (I2R)

  3. Features of Proposal • Backward compatible: • Same modulation scheme – OQPSK + Half-sine pulse shape • Same Symbol-to-Chip mapping, except with shorter code lengths (16/8 chip per symbol) than original length-32 code • 16 sequences for 4-bit mapping, the mapping sequences are related to each other through cyclic shifts and/or conjugation (i.e., inversion of odd-indexed chip values) • Higher rate PHY: • Each sequence consists of 16 or 8 chips instead of 32, which results in 250 kbps and 500 kbps data rate, respectively, given 1 Mcps Francois Chin, Institute for Infocomm Research (I2R)

  4. Adjacent Channel Spectra Francois Chin, Institute for Infocomm Research (I2R)

  5. DDecimal Symbol Binary Symbol Chip Values 0 0 0 0 0 0 0 1 1 0 0 0 1 1 1 1 0 1 0 0 1 (Root Sequence) 1 1 0 0 0 0 1 0 0 1 1 0 0 0 1 1 1 1 0 1 0 2 0 1 0 0 1 0 0 1 0 0 1 1 0 0 0 1 1 1 1 0 3 1 1 0 0 1 0 1 0 0 1 0 0 1 1 0 0 0 1 1 1 4 0 0 1 0 1 1 1 0 1 0 0 1 0 0 1 1 0 0 0 1 5 1 0 1 0 0 1 1 1 1 0 1 0 0 1 0 0 1 1 0 0 6 1 1 1 0 0 0 0 1 1 1 1 0 1 0 0 1 0 0 1 1 7 0 1 1 1 1 1 0 0 0 1 1 1 1 0 1 0 0 1 0 0 8 0 0 0 1 0 1 1 0 0 1 0 0 1 0 1 1 1 1 0 0 9 1 0 0 1 0 0 0 1 1 0 0 1 0 0 1 0 1 1 1 1 10 0 1 0 1 1 1 0 0 0 1 1 0 0 1 0 0 1 0 1 1 11 1 1 0 1 1 1 1 1 0 0 0 1 1 0 0 1 0 0 1 0 12 0 0 1 1 1 0 1 1 1 1 0 0 0 1 1 0 0 1 0 0 13 1 0 1 1 0 0 1 0 1 1 1 1 0 0 0 1 1 0 0 1 14 0 1 1 1 0 1 0 0 1 0 1 1 1 1 0 0 0 1 1 0 15 1 1 1 1 1 0 0 1 0 0 1 0 1 1 1 1 0 0 0 1 Proposed Symbol-to-Chip Mapping (Length-16) The sequences are related to each other through cyclic shifts and/or conjugation (i.e., inversion of odd-indexed chip values) Francois Chin, Institute for Infocomm Research (I2R)

  6. Other Root Sequences (Length-16) • The following Root Sequences are found through exhaustive search with identical low cross correlation and autocorrelation, in base 10: 1719 1899 2919 3021 3027 3261 3387 3438 3693 3798 5067 5838 6042 6054 6447 6522 6774 6777 6876 7062 7386 7596 7827 7977 9039 9189 9534 9789 10134 10527 11319 11343 11676 12057 12084 12099 12477 12777 12894 13044 13359 13548 13554 13752 13959 14124 14427 15117 15192 15501 15537 15627 15654 15909 15954 17103 17139 17307 18078 18681 18831 19068 19398 19503 19578 20163 20259 20268 20361 21054 21474 22587 22638 23016 23352 23427 24114 24198 24216 24813 24954 24999 25017 25209 25554 25788 26088 26379 26529 26718 26739 27096 27108 27399 27504 27918 28173 28248 28779 29379 29544 30234 30384 30921 31002 31074 31254 31308 31329 31818 33717 34206 34227 34281 34461 34533 34614 35151 35301 35991 36156 36756 37287 37362 37617 38031 38136 38427 38439 38796 38817 39006 39156 39447 39747 39981 40326 40518 40536 40581 40722 41319 41337 41421 42108 42183 42519 42897 42948 44061 44481 45174 45267 45276 45372 45957 46032 46137 46467 46704 46854 47457 48228 48396 48432 49581 49626 49881 49908 49998 50034 50343 50418 51108 51411 51576 51783 51981 51987 52176 52491 52641 52758 53058 53436 53451 53478 53859 54192 54216 55008 55401 55746 56001 56346 56496 57558 57708 57939 58149 58473 58659 58758 58761 59013 59088 59481 59493 59697 60468 61737 61842 62097 62148 62274 62508 62514 62616 63636 63816 Francois Chin, Institute for Infocomm Research (I2R)

  7. DDecimal Symbol Binary Symbol Chip Values 0 0 0 0 0 1 0 1 1 0 0 1 0 (Root Sequence) 1 1 0 0 0 0 1 0 1 1 0 0 1 2 0 1 0 0 1 0 1 0 1 1 0 0 3 1 1 0 0 0 1 0 1 0 1 1 0 4 0 0 1 0 0 0 1 0 1 0 1 1 5 1 0 1 0 1 0 0 1 0 1 0 1 6 1 1 1 0 1 1 0 0 1 0 1 0 7 0 1 1 1 0 1 1 0 0 1 0 1 8 0 0 0 1 1 1 1 0 0 1 1 1 9 1 0 0 1 0 0 0 0 1 1 0 0 10 0 1 0 1 1 1 1 1 1 0 0 1 11 1 1 0 1 0 0 0 0 0 0 1 1 12 0 0 1 1 0 1 1 1 1 1 1 0 13 1 0 1 1 1 1 0 0 0 0 0 0 14 0 1 1 1 1 0 0 1 1 1 1 1 15 1 1 1 1 0 0 1 1 0 0 0 0 Proposed Symbol-to-Chip Mapping (Length-8) The sequences are related to each other through cyclic shifts and/or conjugation (i.e., inversion of odd-indexed chip values) Francois Chin, Institute for Infocomm Research (I2R)

  8. Other Root Sequences (Length-8) • The following Root Sequences are found through exhaustive search with identical low cross correlation and autocorrelation, in base 10: 3 6 9 12 18 23 24 29 33 36 43 46 48 53 58 63 66 71 72 77 83 86 89 92 96 101 106 111 113 116 123 126 129 132 139 142 144 149 154 159 163 166 169 172 178 183 184 189 192 197 202 207 209 212 219 222 226 231 232 237 243 246 249 252 Francois Chin, Institute for Infocomm Research (I2R)

  9. Performance Comparison – Sym Err Rate Performance of length-16 and length-8, in comparison with original 802.15.4 PHY length-32 Symbol-to-Chip performance and Orthogonal DSSS sequences as in 15-04-0314-00-004b-enhanced-oqpsk-modulation-with-orthogonal-dsss-sequences Francois Chin, Institute for Infocomm Research (I2R)

  10. System Fading Performance • Channels - Diffuse Exponential Model in IEEE 802.15-04-0337-00-004b • RMS delay spread = 400ns; Chip rate = 1 Mcps • @ 1% PER, Orthogonal DSSS > Seq-16 > Seq-32 > Seq-8 at ~0.5dB intervals Francois Chin, Institute for Infocomm Research (I2R)

  11. Simulation Channels – Diffuse Exponential Model • Diffuse – each delay bin • contains multipath energy • Exponential – average power • decays exponentially • Fading - each delay bin has • independent Rayleigh fading • Single Parameter: • RMS delay spread =  • Mean excess delay  • Max excess delay (10 dB)  2.5 • Max excess delay (20 dB)  5 C = Normalization Constant Ts = Simulation Sample Period Depicted:  = 4Ts Source - IEEE Doc 802.15-04-0337-00-004b Francois Chin, Institute for Infocomm Research (I2R)

  12. Performance Comparison - Correlation • The lower the cross correlation, the lower the symbol error rate • The lower the auto correlation, the better the acquisition capability • Generally, the longer the sequence length, the better the correlation properties • Trade-off better between data rate and desirable correlation properties Francois Chin, Institute for Infocomm Research (I2R)

  13. Performance Comparison – under Constant Transmit Power • Data rate vs Range trade-off – higher data rate at shorter range • Margin between using Seq-32 and Seq-16 is ~ 1dB, Margin between using Seq-16 and Seq-8 is ~ 2dB Francois Chin, Institute for Infocomm Research (I2R)

  14. Summary • Compared to orthogonal DSSS sequences, the length-16 backward compatible symbol-to-chip mapping sequences is only ~0.5 dB worse, while the decoder memory requirement is significantly lower • Effective bandwidth of 1.5MHz for 250kbps / 500 kbps, using length-16 / 8 mapping sequences respectively • Multiple modes (e.g. using 32/16/8 length sequences) can be incorporated into devices for flexible data rate / range performance trade-off Francois Chin, Institute for Infocomm Research (I2R)

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