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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: [Proposal on Preamble Structure for IEEE 802.15.4b PHY] Date Submitted: [Nov 2004] Source: [Liang Li, Liang Zhang, Yafei Tian, Chenyang Yang, Zhijian Hu] 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: [Proposal on Preamble Structure for IEEE 802.15.4b PHY] Date Submitted: [Nov 2004] Source: [Liang Li, Liang Zhang, Yafei Tian, Chenyang Yang, Zhijian Hu] 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: [This contribution proposes preamble structure for TG4 PHY layer.] 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. Outline(1) This Proposal gives the analysis and the part of simulation results around the receiver within the OQPSK + MSK tech. It includes A) Proposes a preamble structure for 15.4b PHY, taking into account the possible needs for the operations of AGC, frame detection, time & frequency synchronization, and channel estimation, etc. Liang Li, WXZJ Inc.

  3. Outline (2) B)Receiver Performance with OQPSK + E16 orthogonal code(MSK) and OQPSK+G16 COBI code are made based on simulations,including: • Synchronization performance comparison: • Auto-correlation characteristics with or without modulation • Synchronization performance in the presence of frequency offset • System performances without RAKE: • Receiver performance comparison based on our simulation results Liang Li, WXZJ Inc.

  4. Proposal for preamble Preamble of 15.4 standard: The preamble field proposed here consists of 6 octets. Preamble here proposed for 15.4b: Liang Li, WXZJ Inc.

  5. Assumptions The proposed preamble structure is based upon the 15.4 experiences and the following assumptions & estimations: • O-QPSK modulation • Proposed E16 orthogonal code (4 bits/symbol) • 6 symbol time allocated for AGC operation (based on 15.4 receiver sensitivity & dynamic range) • Remaining 6 symbol time for operations of frame detection, synchronization, and channel estimation, etc. • The estimated time needed for each operation is relatively conservative, and some margin is included. Liang Li, WXZJ Inc.

  6. Auto-correlation of un-modulated G16 and E16 Auto-correlations of G16[0 0 1 0 1 1 1 1 0 1 0 1 0 0 1 1] and E16 [0 0 1 1 0 1 0 0 0 1 0 0 0 1 0 0] In this test, auto-correlations are calculated directly, using the un-modulated G16 and E16 spreading sequence for sync of preamble. Liang Li, WXZJ Inc.

  7. Auto-correlation of modulated G16 and E16 In this test, both G16 and E16 spreading sequences are first OQPSK modulated with half-sine pulse shaping, and then the correlations are calculated. Auto-correlation of modulatedG16and E16 Liang Li, WXZJ Inc.

  8. About auto-correlation characteristics • The auto-correlation characteristics can have a great impact on system synchronization performance. • E16 code has the auto-correlation characteristics similar to that of G16 when they are not modulated. • With O-QPSK modulation, E16 shows noticeable better characteristics. Liang Li, WXZJ Inc.

  9. System performance comparison without RAKE Simulation parameters & assumptions: • Rayleigh Channel model as suggested at TG4 discussions • O-QPSK modulation + half-sine pulse shaping • 2M sampling rate — 1M chip rate • With or without frequency offset • With or without synchronization error • Center frequency = 915MHz • 20 octets in each packet • 10,000 packets for Monte-Carlo simulation • Non-coherent demodulation • No SFDdetection Liang Li, WXZJ Inc.

  10. Performance Comparison without RAKE PER BER Decode performance of G16 and E16 with 60ppm frequency offset (Synchronization is achieved by correlation method.) Liang Li, WXZJ Inc.

  11. E16 and G16 Multipath Performance(without RAKE) BER PER Simulation parameters: O-QPSK modulation, half-sine pulse shaping, 2M sampling rate, perfect sync, non-coherent demodulation Liang Li, WXZJ Inc.

  12. Observations • At reasonable multipath delay spread (rms=50~250ns), the (without RAKE) receiver of OQPSK + G16 and +MSK +E16 show very similar error-rate performance. • Here, the proved tech (half-sine pulse shaping, 2M over-sampling) with 0db PAR being used and cost of chip is more reasonable to be estimated. • Under the longer delay (600ns), the proven tech is not good enough. However, the model for such a delay may be not reasonable. • The PSD and PAR plots (within OQPSK+MSK(E16) would be provided later. • There are still improve space with OQPSK and the better code. Liang Li, WXZJ Inc.

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