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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: [ System Simulation ] Date Submitted: [ Dec.16, 2004 ] Source: [Liang Li, Liang Zhang, Yafei Tian, Chenyang Yang, Zhijian Hu, HongYu Gu ] Company: [.WXZJ Inc.]

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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: [ System Simulation ] Date Submitted: [ Dec.16, 2004 ] Source: [Liang Li, Liang Zhang, Yafei Tian, Chenyang Yang, Zhijian Hu, HongYu Gu ] Company: [.WXZJ Inc.] Address: [Building D, No.2, Shangdi XinXi Lu, Beijing, China 100085 ] Voice:[8610-13911895301], E-Mail:[liang_1@yahoo.com] Re: [ IEEE 802.15.4 ] Abstract: [The analysis of orthogonal code in OPSK modulation for PHY of 915MHz and 868MHz.] Purpose: [To encourage discussion.] 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. Liang Li, WXZJ Inc.

  2. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [ Analysis of E16 for 868/915 Band PHY] Date Submitted: [Dec. 2004 ] Source: [Liang Li, Liang Zhang, Yafei Tian, Chenyang Yang, Zhijian Hu ] Company: [WXZJ] Address: [2 Xinxi St, Building D, Haidian District, Beijing, China 100085 ] Voice:[86-10-139-11895301], E-Mail:[liang_1@yahoo.com] Re: [ IEEE 802.15.4 ] Abstract: [Analysis of E16 orthogonal spreading code for 868/915MHz band PHY.] Purpose: [To encourage discussion.] 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. Liang Li, WXZJ Inc.

  3. Overview This document offers key parameters of E16, and the system performances of E16 orthogonal code for 915MHz and 868MHz system: • 915MHz PHY: • PSD of E16 and PHY parameters • Synchronization performance - in the presence of frequency offset • System performance Sync error, phase noise, sampling error, frequency offset, Rayleigh channel, • 868MHz PHY: • PSD of E16 and PHY parameters • Synchronization performance - in the presence of frequency offset • System performance Sync error, phase noise, sampling error, frequency offset, Rayleigh channel, Liang Li, WXZJ Inc.

  4. OPSK variants reviewed in this presentation Liang Li, WXZJ Inc.

  5. Decimal Symbol Binary Symbol Chip Values 0 0 0 0 0 0 0 1 1 0 1 0 0 0 1 0 0 0 1 0 0 1 1 0 0 0 0 1 1 0 0 0 0 1 0 0 0 1 0 0 0 1 2 0 1 0 0 0 0 0 0 0 1 1 1 0 1 1 1 0 1 1 1 3 1 1 0 0 0 1 0 1 0 0 1 0 0 0 1 0 0 0 1 0 4 0 0 1 0 0 0 1 1 1 0 1 1 0 1 0 0 1 0 1 1 5 1 0 1 0 0 1 1 0 1 1 1 0 0 0 0 1 1 1 1 0 6 1 1 1 0 0 0 0 0 1 0 0 0 0 1 1 1 1 0 0 0 7 0 1 1 1 0 1 0 1 1 1 0 1 0 0 1 0 1 1 0 1 8 0 0 0 1 0 0 1 1 0 1 0 0 1 0 1 1 1 0 1 1 9 1 0 0 1 0 1 1 0 0 0 0 1 1 1 1 0 1 1 1 0 10 0 1 0 1 0 0 0 0 0 1 1 1 1 0 0 0 1 0 0 0 11 1 1 0 1 0 1 0 1 0 0 1 0 1 1 0 1 1 1 0 1 12 0 0 1 1 0 0 1 1 1 0 1 1 1 0 1 1 0 1 0 0 13 1 0 1 1 0 1 1 0 1 1 1 0 1 1 1 0 0 0 0 1 14 0 1 1 1 0 0 0 0 1 0 0 0 1 0 0 0 0 1 1 1 15 1 1 1 1 0 1 0 1 1 1 0 1 1 1 0 1 0 0 1 0 DSSS Sequence E16 The spread sequence corresponding to binary symbol “0000” is used for sync Liang Li, WXZJ Inc.

  6. OPSK Proposal E16 Orthogonal Spreading Sequence for 915 MHz PHY Liang Li, WXZJ Inc.

  7. 915 MHz Band PHY •Key design parameters –Summary of design requirements for the TG4b PHY •PSD of E16 •Auto-correlation performance of E16 – Auto-correlation ofO-QPSK with half sine pulse shaping / I/Q modulation at 2x sampling rate – sync in condition of frequency offset • E16 Performance – simulation condition or system construction – AWGN and Rayleigh channel in ideal condition – Frame detection, synchronization, phase noise, frequency offset, sampling error, respectively (to be continued) •Summary Liang Li, WXZJ Inc.

  8. Key Parameters of E16 • Bit rate 250 kBit/s • Better orthogonal characteristic • 16 sequences for 4 bits mapping • Each consist of 16 chips • 1M chip rate per second • Center frequency is 915MHz; • Bandwidth, Pulse shape , PAPR, frequency offset • The 1st null-null bandwidth 1.5MHz; • Half-sine pulse shape; • 0dB PAPR, the same MSK scheme as 15.4, constant module and continuous phase,lower out-of-band emission; • 30dB lower over 2M wide bandwidth, which satisfies the state of 15.4; • Tolerated frequency offset at least 40ppm; • Multipath fading robustness • Achieve PER<10^-2 at channels with 250ns delay spread ((Multipath channel model offer by Paul with high sampling rate); • Support of current RF • Support 2 MHz wide channels in the USA and other countries were they are permitted • Low cost and low power consumption Liang Li, WXZJ Inc.

  9. PSD of Tx Waveform (OQPSK+E16) • Bandwidth, Pulse shape: • The 1st null-null bandwidth 1.5MHz; Half-sine pulse shape: • MSK modulation offers constant modulus and continuous phase; • PSD 30dB lower at 1.5MHz from center frequency. Liang Li, WXZJ Inc.

  10. PSD Characteristic • PSD of OQPSK+E16 at 915Band is not affected by sampling error. • Low out-of-band emission, and no need for Tx filter • Satisfies the IEEE 802.15.4 PSD requirements (in the 915 band) Source: IEEE 802.15.4 Standard Liang Li, WXZJ Inc.

  11. Auto-correlation performance Synchronization performance of E16 based on simulations: • Auto-correlation characteristics with MSK modulation in 2x sampling rate • Synchronization performance in the presence of frequency offset Liang Li, WXZJ Inc.

  12. Auto-correlation of modulated E16 In this test, E16 spreading sequences are first OQPSK modulated with half-sine pulse shaping, and then the correlations are calculated. Auto-correlation of modulatedE16 Liang Li, WXZJ Inc.

  13. Synchronization performance Simulation parameters & assumptions: • Rayleigh Channel model as suggested at TG4 discussions • O-QPSK + half-sine pulse shaping • 2M sampling rate (1M chips/sec) • Frequency offset from 0ppm to 40ppm • Center frequency = 915MHz • Average over 1 million Monte-Carlo simulations Notes: • Synchronization is achieved by correlating local PN with received preamble impaired by frequency offset. • Throughout this document, the perfect synchronization (no error) in a multipath environment is defined as the receiver being synchronized to the strongest path. Liang Li, WXZJ Inc.

  14. AWGN Model---Synchronization performance Liang Li, WXZJ Inc.

  15. System performance Simulation parameters & assumptions: • 250ns rms delay spread Rayleigh Channel model • O-QPSK modulation + half sine pulse • without frequency offset • without synchronization error • 20 octets in each packet • 10,000 packets for Monte-Carlo simulation • Non-coherent demodulation • No SFDdetection • No fading Liang Li, WXZJ Inc.

  16. Simulation models Discrete exponential channel model –-Sampled version of diffuse channel model offer by Paul with 4MHz sampling rate; –At least 10000 random channel realizations; –PER calculated on 20 bytes PPDUs with preamble; Liang Li, WXZJ Inc.

  17. AWGN: Ideal Sync. vs. Correlation Sync. Packet Number: 10000 PSDU Length: 20 Byte Tx/Rx Over Sample Rate: 2 Channel Over Sample Rate: 4 Frame Detection: No SFD: No Liang Li, WXZJ Inc.

  18. AWGN simulation results • The BER results are close to the theoretical curve of 16-FSK. • The sync error (using received signals correlated directly with local PN) has minimal effects on performance curves at low Eb/N0, and almost no effects in high SNR condition. Liang Li, WXZJ Inc.

  19. Multiple-path Model without Fading + Correlation Sync. Packet Number: 10000 PSDU Length: 20 Byte Tx/Rx Over Sample Rate: 2 Channel Over Sample Rate: 4 Frame Detection: No Phase noise :No SFD: No Sync.: Correlation Down sampling error: No Liang Li, WXZJ Inc.

  20. Multiple-path model without Fading + Correlation Sync. Packet Number: 10000 PSDU Length: 20 Byte Tx/Rx Over Sample Rate: 2 Channel Over Sample Rate: 4 Frame Detection: No Phase noise :No SFD: No Sync.: Correlation Down sampling error: Yes Liang Li, WXZJ Inc.

  21. Multiple-path model without Fading + Correlation Sync. Frame Detection: No Phase noise :YES SFD: No Sync.: Correlation Down sampling error: No Packet Number: 10000 PSDU Length: 20 Byte Tx/Rx Over Sample Rate: 2 Channel Over Sample Rate: 4 Liang Li, WXZJ Inc.

  22. Multiple-path model without Fading + Correlation Sync. Frame Detection: No Phase noise :YES SFD: YES Sync.: Correlation Down sampling error: No Packet Number: 10000 PSDU Length: 20 Byte Tx/Rx Over Sample Rate: 2 Channel Over Sample Rate: 4 Liang Li, WXZJ Inc.

  23. Multiple-path model without Fading + Correlation Sync. Frame Detection: YES Phase noise :YES SFD: Yes Sync.: Correlation Down sampling error: No Packet Number: 10000 PSDU Length: 20 Byte Tx/Rx Over Sample Rate: 2 Channel Over Sample Rate: 4 Liang Li, WXZJ Inc.

  24. Multiple-path model without Fading + Correlation Sync. Frame Detection: YES Phase noise :YES SFD: Yes Sync.: Correlation Down sampling error: Yes Packet Number: 10000 PSDU Length: 20 Byte Tx/Rx Over Sample Rate: 2 Channel Over Sample Rate: 4 Liang Li, WXZJ Inc.

  25. Multiple-path modelwith Fading + Correlation Sync. Frame Detection: No Phase noise :No SFD: No Sync.: Correlation Down sampling error: No Packet Number: 10000 PSDU Length: 20 Byte Tx/Rx Over Sample Rate: 2 Channel Over Sample Rate: 4 Liang Li, WXZJ Inc.

  26. Multiple-path modelwith Fading + Correlation Sync. Frame Detection: Yes Phase noise :Yes SFD: Yes Sync.: Correlation Down sampling error: No Packet Number: 10000 PSDU Length: 20 Byte Tx/Rx Over Sample Rate: 2 Channel Over Sample Rate: 4 Liang Li, WXZJ Inc.

  27. OQPSK Proposal E16 Orthogonal Spreading Sequence for 868 MHz PHY Liang Li, WXZJ Inc.

  28. Key Parameters of E16 • Bit rate 100 kBit/s • Better orthogonal characteristic • 16 sequences for 4 bits mapping • Each consist of 16 chips • 400k chip rate per second • Center frequency is 868MHz; • Bandwidth, Pulse shape , PAPR, frequency offset • The 1st null-null bandwidth 600kHz; • 0dB PAPR, • GMSK modulation with r=0.2, constant module and continuous phase,lower out-of-band emission; • Nearly 50dB lower over 600kHz wide bandwidth, which satisfies the state of ETSI; • Tolerated frequency offset at least 40ppm; • Multipath fading robustness • Achieve PER<10^-2 at channels with 250ns delay spread (Multipath channel model offer by Paul with high sampling rate); • Support of current RF • Support current 600kHz band available at 1% duty cycle in Europe today • Allow use of extended European bands and bands in other countries once they become available • Allow addition of additional 600 kHz channels as per current ETSI / ECC report (4/6 channels?) • Do not expect US-like wide, unrestricted bands or all egulatorydomains • Support of more flexible channel selection method to flexibly add support for more countries • Low cost and low power consumption Liang Li, WXZJ Inc.

  29. OPSK variants reviewed in this presentation Liang Li, WXZJ Inc.

  30. 868 MHz Band PHY •Key design parameters –Summary of design requirements for the TG4b PHY •PSD of TX waveform at 868MHz • RX Performance with E16 at 868MHz Band –simulation condition or system construction –AWGN and Rayleigh channel (theoretical PER results) in ideal condition –Frame detection, synchronization, phase noise, frequency offset, sampling error, respectively (to be continued) •Summary Liang Li, WXZJ Inc.

  31. Simulation models use Discrete exponential channel model –-Sampled version of diffuse channel model offer by Paul with 4x sampling rate; –At least 10000 random channel realizations; –PER calculated on 20 bytes PPDUs with preamble; Liang Li, WXZJ Inc.

  32. Ia. OQPSK + half sine pulse without Tx filter Tx / Rx performance at 868MHz, 600KHz bandwidth • E16 orthogonal code + OQPSK + half-sine pulse shaping • Tx: PSD, No shaping Filter; • RX: Synchronization performance • Receiver (Non-Rake) performance comparison based on our simulation results Liang Li, WXZJ Inc.

  33. 100kbps Data rate PSD • 100kbps; • 400k chip rate; • 600k bandwidth; • half sine pulse shape; • No Tx filter; Liang Li, WXZJ Inc.

  34. 100kbps Data rate performance Packet Number: 10000 PSDU Length: 20 Byte Tx/Rx Over Sample Rate: 2 Channel Over Sample Rate: 4 Frame Detection: No SFD: No Ideal sync Liang Li, WXZJ Inc.

  35. Ib. OQPSK + half sine pulse with Tx filter Tx / Rx Performance at 868MHz, 600KHz bandwidth Assumption: • E16 orthogonal code + OQPSK + half-sine pulse shaping • Tx: PSD, 6 taps Tx digital raised cosine filter with r=0.2; • Rx: Synchronization performance • Receiver (Non-Rake) performance comparison based on our simulation results In the following slides, two Tx filters will be analyzed at 2x sampling rate and 4x sampling rate, respectively. Liang Li, WXZJ Inc.

  36. Freq Response – raised cosine filter r=0.2 SUPPOSE: 1, 0.8MHz (2x)sampling rate; 2, 250kHz pass band; 3, Tx digital FIR filter; 4, 6 taps; Liang Li, WXZJ Inc.

  37. Impulse response of Tx filter –raised cosine filter r=0.2 SUPPOSE: 1, 0.8MHz (2x)sampling rate; 2, 250kHz pass band; 3, Tx digital FIR filter; 4, 6 taps; Liang Li, WXZJ Inc.

  38. 100kbps Data rate PSD with Tx filter • 100kbps; • 400k chip rate; • 600k bandwidth; • half sine pulse shape; • 6 taps FIR Tx filter; • Raised cosine filter with r=0.2; • 2x over sampling rate; (0.8M sampling rate) Liang Li, WXZJ Inc.

  39. PAPR of 100kbps with Tx filter PAPR is less than 1dB (about 0.8~0.9dB) The amplitudes of samples after Tx filter Liang Li, WXZJ Inc.

  40. 100kbps Data rate performance Packet Number: 10000 PSDU Length: 20 Byte Tx/Rx Over Sample Rate: 2 Channel Over Sample Rate: 4 Frame Detection: No SFD: No Ideal sync Tx filter Liang Li, WXZJ Inc.

  41. Freq Response --- 0 raised cosine filter r=0.2 SUPPOSE: 1, 1.6MHz (4x)sampling rate; 2, 250kHz pass band; 3, Tx digital FIR filter; 4, 8 taps; Liang Li, WXZJ Inc.

  42. Impulse response of Tx filter –raised cosine filter r=0.2 SUPPOSE: 1, 0.8MHz (4x)sampling rate; 2, 250kHz pass band; 3, Tx digital FIR filter; 4, 6 taps; Liang Li, WXZJ Inc.

  43. 100kbps Data rate PSD with Tx filter • 100kbps; • 400k chip rate; • 600k bandwidth; • half sine pulse shape; • 8 taps FIR Tx filter; • Raised cosine filter with r=0.2; • 4x over sampling rate; (1.6M sampling rate) Liang Li, WXZJ Inc.

  44. PAPR of 100kbps with Tx filter PAPR is less than 1dB (about 0.4~0.5dB) The amplitudes of samples after Tx filter Liang Li, WXZJ Inc.

  45. Nonlinear PA Characteristics Liang Li, WXZJ Inc.

  46. Impact of PA Nonlinearity: 2x sampling rate (2) (1) (1) Tx PSD without Tx filter or PA (2) Tx PSD with Tx filter, no PA (3) Tx PSD with Tx filter and PA Because of aliasing at relatively low sampling rate, the signal side-lobe is susceptible to PA nonlinearity. (3) Liang Li, WXZJ Inc.

  47. Impact of PA Nonlinearity: 4x sampling rate (2) (1) (1) Tx PSD without Tx filter or PA (2) Tx PSD with Tx filter, no PA (3) Tx PSD with Tx filter and PA At 4x sampling rate, the impact of PA nonlinearity is neglectable. (3) Liang Li, WXZJ Inc.

  48. II. GMSK TX/ RX Performance within 600KHz at 868MHz Assumption: • E16 Orthogonal code +GMSK • TX: PSD, No filter; • RX: Synchronization performance • Receiver (Non-Rake) performance comparison based on our simulation results Liang Li, WXZJ Inc.

  49. GMSK sequences generated Method I : Method II : Liang Li, WXZJ Inc.

  50. 100kbps Data rate – GMSK modulation • 100kbps; • 400k chip rate; • 600k bandwidth; • half sine pulse shape; • No Tx filter; • Gaussian filter before MSK modulation with r=0.2 Liang Li, WXZJ Inc.

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