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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: [Merged UWB proposal for IEEE 802.15.4a Alt-PHY] Date Submitted: [22 Feb 2005] Source: [Francois Chin, et.al.] Company: [Institute for Infocomm Research, Singapore] Address: [21 Heng Mui Keng Terrace, Singapore 119613] Voice: [65-68745687] FAX: [65-67744990] E-Mail: [chinfrancois@i2r.a-star.edu.sg] Re: [Response to the call for proposal of IEEE 802.15.4a, Doc Number: 15-04-0380-02-004a ] Abstract: [Merged Proposal to IEEE 802.15.4a Task Group] Purpose: [For presentation and consideration by the IEEE802.15.4a committee] 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 (I2R), et. al.

  2. This contribution is a technical merger between*: Institute for Infocomm Research [05/032] General Atomics [05/016] Thales & Cellonics [05/008] KERI & SSU & KWU [05/033] Create-Net & China UWB Forum[05/019] Staccato Communications [04/0704] Wisair [05/09] * For a complete list of authors, please see page 3. Francois Chin (I2R), et. al.

  3. Authors Institute for Infocomm Research: Francois Chin, Xiaoming Peng, Sam Kwok, Zhongding Lei, Kannan, Yong-Huat Chew, Chin-Choy Chai, Rahim, Manjeet, T.T. Tjhung, Hongyi Fu, Tung-Chong Wong General Atomics: Naiel Askar, Susan Lin Thales & Cellonics: Serge Hethuin, Isabelle Bucaille, Arnaud Tonnerre, Fabrice Legrand, Joe Jurianto KERI & SSU & KWU: Kwan-Ho Kim, Sungsoo Choi, Youngjin Park, Hui-Myoung Oh, Yoan Shin, Won cheol Lee, and Ho-In Jeon Create-Net & China UWB Forum: Zheng Zhou, Frank Zheng, Honggang Zhang, Xiaofei Zhou, Iacopo Carreras, Sandro Pera, Imrich Chlamtac Staccato Communications: Roberto Aiello, Torbjorn Larsson Wisair: Gadi Shor, Sorin Goldenberg Francois Chin (I2R), et. al.

  4. Multiband Ternary Orthogonal Keying (M-TOK) for IEEE 802.15.4a UWB based Alt-PHY Francois Chin (I2R), et. al.

  5. Goals • Good use of UWB unlicensed spectrum • Good system design • Path to low complexity CMOS design • Path to low power consumption • Scalable to future standards • Graceful co-existence with other services • Graceful co-existence with other UWB systems • Support different classes of nodes, with different reliability requirements (and $), with single common transmit signaling Francois Chin (I2R), et. al.

  6. Main Features Proposal main features: • Impulse-radio based (pulse-shape independent) • Common preamble signaling for different classes of nodes / type of receivers (coherent / differential / noncoherent) • Band Plan based on multiple 500 MHz bands • Robustness against SOP interference • Robustness against other in-band interference • Scalability to trade-off complexity/performance Francois Chin (I2R), et. al.

  7. Proposed System Parameters Francois Chin (I2R), et. al.

  8. System Description • Each piconet uses one set of code sequences for different classes of nodes / type of receivers (coherent / differential / non-coherent receivers) • 16 Orthogonal Sequences of code length 32 to represent a 4-bit symbol • PRF (chip rate): 24 MHz • Low enough to avoid significant interchip interference (ICI) with all 802.15.4a multipath models • High enough to ensure low pulse peak power • FEC: optional (or low complexity type) Francois Chin (I2R), et. al.

  9. Band Plan Francois Chin (I2R), et. al.

  10. Multiple access Multiple access within piconet: TDMA+CSMA/CA same as 15.4 Multiple access across piconets: CDM + FDM Different Piconet uses different Base Sequence & different 500 MHz band Francois Chin (I2R), et. al.

  11. Types of Receivers Supported • Coherent Detection: The phase of the received carrier waveform is known, and utilized for demodulation • Differential Chip Detection: The carrier phase of the previous signaling interval is used as phase reference for demodulation • Non-coherent Detection: The carrier phase information (e.g.pulse polarity) is unknown at the receiver Francois Chin (I2R), et. al.

  12. Criteria of Code Sequence Design • The sequence Set should have orthogonal (or near orthogonal) cross correlation properties to minimise symbol decision error for all the below receivers • For coherent receiver • For differential chip receiver • For non-coherent symbol detection receiver • Energy detection receiver • Each sequence should have good auto-correlation properties Francois Chin (I2R), et. al.

  13. Criteria of Code Sequence Design • To minimise impact of DC noise effect on energy collector based non-coherent receiver • For OOK signaling, the transmitter transmits {+1,-1,0} ternary sequences • Conventional receive unipolar code sequence – follows transmit sequence • After the energy capture in the receiver, the noise has positive DC components in each chip; error occurs in thresholding, especially at lower SNR • This will accumulate noise unevenly in symbol decision • An ideal receive despreading chip sequence should then have bipolar chip values, preferrably with equal number of ‘+1 and ‘-1’ chips • This, to certain extent, will nullify DC noise energy in symbol decision • This, will also nullify energy components from other interfering piconets Francois Chin (I2R), et. al.

  14. Base Sequence Set • 31-chip Ternary Sequence set are chosen • Only one sequence and one fixed band (no hopping) will be used by all devices in a piconet • Logical channels for support of multiple piconets • 6 sequences = 6 logical channels (e.g. overlapping piconets) for each FDM Band • The same base sequence will be used to construct the symbol-to-chip mapping table Francois Chin (I2R), et. al.

  15. Symbol-to-Chip Mapping: Gray coded 16-ary Ternary Orthogonal Keying To obtain 32-chip per symbol, cyclic shift the Base Sequence first, then append a ‘0’-chip in front Base Sequence #1 Francois Chin (I2R), et. al.

  16. Good Properties of the Mapping Sequence • Cyclic nature, leads to simple implementation • Zero DC for each sequence • No need for carrier phase tracking (i.e. coherent receiver) Francois Chin (I2R), et. al.

  17. Synchronisation Preamble Correlator output for synchronisation • Code sequences has good autocorrelation properties • Preamble is constructed by repeating ‘0000’ symbols • Long preamble is constructed by further symbol repetition Francois Chin (I2R), et. al.

  18. Frame Format 2 1 0/4/8 n 2 Octets: Data Payload MAC Sublayer Frame Cont. Seq. # Address CRC MHR MSDU MFR Data: 32 (n=23) 4? For ACK: 5 (n=0) 1 1 Octets: PHY Layer Frame Length Preamble SFD MPDU SHR PHR PSDU PPDU Francois Chin (I2R), et. al.

  19. Transmission Mode Francois Chin (I2R), et. al.

  20. Modulation & Coding (Mode 1) Binary data From PPDU Symbol- to-Chip Bit-to- Symbol Symbol Repetition Pulse Generator Bit to symbol mapping: group every 4 bits into a symbol Symbol-to-chip mapping: Each 4-bit symbol is mapped to one of 16 32-chip sequence, according to 16-ary Ternary Orthogonal Keying Symbol Repetition: for data rate and range scalability Pulse Genarator: • Transmit Ternary pulses at PRF = 24MHz {0,1,-1} Ternary Sequence Francois Chin (I2R), et. al.

  21. Modulation & Coding (Mode 2) Binary data From PPDU Symbol- to-Chip Pulse Generator Bit-to- Symbol Symbol Repetition Ternary- Binary Bit to symbol mapping: group every 4 bits into a symbol Symbol-to-chip mapping: Each 4-bit symbol is mapped to one of 16 32-chip sequence, according to 16-ary Ternary Orthogonal Keying Symbol Repetition: for data rate and range scalability Ternary to Binary conversion: (-1/+1 → 1,0 → -1) Pulse Genarator: • Transmit bipolar pulses at PRF = 24MHz {1,-1} Binary Sequence {0,1,-1} Ternary Sequence Francois Chin (I2R), et. al.

  22. Auto Correlation Properties for Non-Coherent Symbol Detection Receiver Francois Chin (I2R), et. al.

  23. Cross Correlation Properties for Coherent Detection Receiver TxSeqSet * RxSeqSet' (Mode 1) = TxSeqSet * RxSeqSet' (Mode 2) = Francois Chin (I2R), et. al.

  24. Differential Multipath Combining Francois Chin (I2R), et. al.

  25. Auto Correlation Properties for Differential Chip Detection Receiver Francois Chin (I2R), et. al.

  26. Cross Correlation Properties for Differential Chip Detection Receiver DifferentialChip(TxSeqSet) * DifferentialChip(RxSeqSet)’ (Mode 2) = DifferentialChip(TxSeqSet) * DifferentialChip(RxSeqSet)’ (Mode 1) = Francois Chin (I2R), et. al.

  27. Non-Coherent Receiver Architectures (Mode 1) LPF / integrator Soft Despread BPF ( )2 ADC • Energy detection technique rather than coherent receiver, for low cost, low complexity • Soft chip values gives best results • Oversampling & sequence correlation is used to recovery chip timing recovery • Synchronization fully re-acquired for each new packet received (=> no very accurate timebase needed) Sample Rate 1/Tc Francois Chin (I2R), et. al.

  28. Auto Correlation Properties for Energy Detection Receiver (Mode 1) Francois Chin (I2R), et. al.

  29. Cross Correlation Properties for Energy Detection Receiver (Mode 1) TxSeqSet * RxSeqSet ' = Francois Chin (I2R), et. al.

  30. AWGN Performance Francois Chin (I2R), et. al.

  31. AWGN Performance • AWGN performance @ 1% PER Francois Chin (I2R), et. al.

  32. Basic Data Rate Throughput (Low Rate Modes) • Useful data rate calculation for 32 byte PSDU (Xo = 0.75 Mbps) • Symbol Period = 1.33us • Data frame time : 38 x 8 / 0.75= 405.3 µsec • ACK frame time : 11 x 8 / 0.75 = 117.3 µsec • tACK (considering 15.4 spec) : 192 µsec • LIFS (considering 15.4 spec) : 640 µsec • Tframe = 1355 µsec • Useful Basic Data Rate = 189.0 kbps Francois Chin (I2R), et. al.

  33. Basic Data Rate Throughput (High Rate Modes) • Useful data rate calculation for 32 byte PSDU (Xo = 3 Mbps) • Symbol Period = 1.33us • Data frame time : 38 x 8 / 3 = 101.3 µsec • ACK frame time : 11 x 8 / 3 = 29.3 µsec • tACK (considering 15.4 spec) : 192 µsec • LIFS (considering 15.4 spec) : 640 µsec • Tframe = 963 µsec • Useful Basic Data Rate = 265.9 kbps Francois Chin (I2R), et. al.

  34. Basic Data Rate Throughput (High Rate Modes) • Useful data rate calculation for 127 byte PSDU (Xo = 3 Mbps) • Symbol Period = 1.33us • Data frame time : 127 x 8 / 3 = 354.7 µsec • ACK frame time : 11 x 8 / 3 = 29.3 µsec • tACK (considering 15.4 spec) : 192 µsec • LIFS (considering 15.4 spec) : 640 µsec • Tframe = 1216 µsec • Useful Basic Data Rate = 853.5 kbps Francois Chin (I2R), et. al.

  35. Link Budget Francois Chin (I2R), et. al.

  36. Ranging and Positioning Francois Chin (I2R), et. al.

  37. Asynchronous Ranging Scheme • Synchronous ranging • One way ranging • Simple TOA/TDOA measurement • Universal external clock • Asynchronous ranging • Two way ranging • TOA/TDOA measurement by RTTs • Half-duplex type of signal exchange TOF : Time Of Flight RTT : Round Trip Time SHR : Synchronization Header But, High Complexity Asynchronous Ranging Synchronous Ranging Francois Chin (I2R), et. al.

  38. Proposed Positioning Scheme Features- Sequential two-way ranging is executed via relay transmissions- PAN coordinator manages the overall schedule for positioning- Inactive mode processing is required along the positioning- PAN coordinator may transfer all sorts of information such as observed - TDOAs to a processing unit (PU) for position calculationBenefits- It does not need pre-synchronization among the devices- Positioning in mobile environmentis partly accomplished P_FFD3 P_FFD2 TOA 24 TOA 34 RFD PAN coordinator TOA 14 PU P_FFD : Positioning Full Function Device RFD : Reduced Function Device P_FFD1 Francois Chin (I2R), et. al.

  39. Process of Proposed Positioning Scheme TOA measurement Francois Chin (I2R), et. al.

  40. RTT12 = T + 2T12 RTT23 = T + 2T23 RTT13 = T12 + 2T + T23 + T13 More Details for obtaining TDOAs • Distances among the positioning FFDs are calculated from RTT measurements and known time interval T • Using observed RTT measurements and calculated distances, TOAs/TDOAs are updated T12 = (RTT12 – T)/2 T23 = (RTT23 – T)/2 T13 = (RTT13 – T12 – T23 – 2T) RTT34 = T34 + T + T34 TOA34 = (RTT34 - T)/2 RTT24 = T23 + T + T34 + T + T24 TOA24 = (RTT24 - T23 - TOA34 - 2T) TOA14 = (RTT14 - T12 - T23 - TOA34 - 3T) RTT14 = T12 + T + T23 + T + T34 + T + T14 TDOA12 = TOA14 – TOA24 TDOA23 = TOA24 – TOA34 Francois Chin (I2R), et. al.

  41. Position Calculation using TDOAs • The range difference measurement defines a hyperboloid of constant range difference • When multiple range difference measurements are obtained, producing multiple hyperboloids, the position location of the device is at the intersection among the hyperboloids Francois Chin (I2R), et. al.

  42. PAN Coordinator FFD RFD Positioning FFD(P_FFD) Positioning Scenario Overview • Using static reference nodes in relatively large scaled cluster : • Power control is required • Power consumption increases • All devices in cluster must be in inactive data transmission mode • Using static and dynamic nodes in overlapped small scaled sub-clusters : • Sequential positioning is executed in each sub-cluster • Low power consumption • Associated sub-cluster in positioning mode should be in inactive data transmission mode • Case 1 Cluster 1 • Case 2 Cluster 1 Francois Chin (I2R), et. al.

  43. Positioning Scenario for Star topology • Star topology • PAN coordinator activated mode • Positioning all devices • Re-alignment of positioning FFD’s list is not required • Target device activated mode • Positioning is requested from some device • Re-alignment of positioning FFD’s list is required Francois Chin (I2R), et. al.

  44. Positioning Scenario for Cluster-tree Topology • Cluster-tree topology Francois Chin (I2R), et. al.

  45. Analog Energy Window Bank Francois Chin (I2R), et. al.

  46. Ranging Accuracy Improvement • Technical requirement for positioning • “It can be related to precise (tens of centimeters) localization in some cases, but is generally limited to about one meter” • Parameters for technical requirement • Minimum required pulse duration : • Minimum required clock speed for the correlator in the conventional coherent systems High Cost ! • Fast ADC clock speed in the conventional coherent receiver is required for the digital signal processing Francois Chin (I2R), et. al.

  47. Analog Energy Window Bank (1) • Digital signal processing with fast clock can be replaced by using analog energy window bank with low clock speed • Why analog energy window bank? • Conventional single energy window may support the energy detection for data demodulation in the operation mode • However, this cannot guarantee the correct searching of the signal position in the timing mode (that also means the ambiguity of ranging accuracy) • Analog energy window bank can sufficiently support timing and calibration as well as operation mode • Widow Bank Size : ~4 nsec (smallest pulse duration) • The number of energy windows in a bank : 11 • Operation clock speed of each energy window : 24 MHz • Number of the required energy windows depends on the power delay profile of the multipath channel (effective multipath components) Francois Chin (I2R), et. al.

  48. Size of the Integrated Bank (S) First Path Estimation and Calibration Analog Energy Window Bank (2) Francois Chin (I2R), et. al.

  49. Modifying MAC Francois Chin (I2R), et. al.

  50. Modifications of MAC Command Frame (1) • Features • Frame control field • frame type : positioning (new addition using a reserved bit) • Command frame identifier field • Positioning request/response (new addition) • Positioning parameter information field • Absolute coordinates of positioning FFDs • POS range • List of positioning FFDs and target devices • Power control • Pre-determined processing time (T) Francois Chin (I2R), et. al.