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

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  1. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title:Joint ULP-GFSK PHY layer proposal Date Submitted: January 2014 Source:Henk de Ruijter, Ping Xiong, Silicon Labs Frederik Beer, Jörg Robert, Friedrich-Alexander University (FAU) / Fraunhofer IIS Steve Jillings, Semtech Rick Powell, Microsemi Corp Abstract:Presentation on joint ULP-GFSK PHY proposal Purpose: Providing direction towards a ULP PHY standard 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.

  2. Henk de Ruijter, Ping Xiong Frederik Beer, Jörg Robert, Steve Jillings Rick Powell January, 2014 Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Joint ULP-GFSK PHY layer proposal

  3. Outline: Introduction ULP-GFSK proposal Evaluation Miscellaneous Abbreviations References Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  4. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Introduction

  5. Joint Proposal: This is a joint proposal merging: 15-13-0709-00-004q  ULP-GFSK PHY proposal 15-13-0702-00-004q  GMSK/FEC proposal Motivation for merging: Both proposals employ Gaussian filtering Both proposals employ GFSK (GMSK = GFSK with h = 0.5) Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  6. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Motivation – Application • Suitable devices for an ULP standard are for example Smart/Shelf Labels • Smart/Shelf Labels may be used in supermarkets or warehouses where instant price adjustments or real-time inventory is desirable

  7. Summary: This proposal, ULP-GFSK PHY, can be considered as an extension, adding some additional options to the MR-FSK PHY (as defined in the 802.15.4g amendment [1]) to help reduce power and energy consumption This will have the following benefits: The similarities to the MR_FSK PHY will reduce development cost for implementers as well as chip vendors. Piggyback on an existing and successful PHY standard will help to expedite industrial acceptance. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  8. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell MR-FSK PHY for Energy efficient links for SUN: PRO’s: Constant envelop  high efficiency PA Industry acceptance: ZigBee-NAN, Wi-SUN, ETSI Short comings for ULP applications: Excessive overhead in PPDU for ULP applications Data rates not high enough for short transmissions Limited possibilitiestoleverageasymmetric links Addressed by this proposal

  9. Network Structure: By including (precoded) GMSK this proposal provides options for asymmetric links which can occur in communication between a concentrator (or base station) and an end devices (e.g. shelf label). The concentrator may have a larger power source and more computing power for more complex algorithms (in contrast to the low power end devices) which could be used to enhance receiver sensitivity and increase the TX output power. Positive side-effects of a centralized approach: No power needed for routing and path management No additional power consumption for ULP end-devices near the destination due to relaying frames Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  10. Asymmetric Links: Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell • Simple ULP end-devices • Limited transmit power • Limited computing power • More complex concentrator • Higher transmit power • Sophisticated RX algorithms Example:

  11. Power savings of this proposal: Power is being saved by: Increase data rate to reduce the receiver and transmitter ON time. Increased Rate mode without re-sync required Reducedtransmit power foruplink Higher tolerable noise figure Moreover energy is being saved by reducingoverhead: 1 octet PHY header (vs 2 octet in MR-FSK PHY) Optional 2 octet preamble (vs 4 octet in MR-FSK PHY) Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  12. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Proposal

  13. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Modulator Similar to MR-FSK:

  14. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell PPDU format: Same as MR-FSK:

  15. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Preamble: To reduce overhead (and save power): The minimum preamble for the ULP-GFSK PHY is reduced to 2 octet. The PHY PIB attribute “phyFSKPreambleLength” will be made available for ULP-GFSK. The description in table 71 needs to reflect that and describe the related value range of 2 – 15for ULP-GFSK. Common with MR-FSK: The Preamble field shall contain phyFSKPreambleLength(as defined in 9.3, see 802.15.4g-2012 [1]) multiples of the 8-bit sequence “01010101” for filtered 2FSK.

  16. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell SFD: The SFD in ULP-GFSK is specified as follows Note: Additional SFDs forprecodedsignalsare not necessary. Note: The SFD for the 4GFSK modes are the same as in Table 132 in section 18.1.1.2 of [1]

  17. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Forward Error Correction: Two convolutional forward error correction schemes are proposed: R=1/2, K=4 (15,17) scheme from IEEE 802.15.4g R=1/2, K=7 (133,171) scheme from IEEE 802.15.4k Both schemes are easy to encode Compared to block codes convolutional codes have the advantage of being packet length agnostic Well-known usage of soft-decoding possible with deterministic processing latency

  18. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Mandatory PHY Header (PHR): The ULP-FSK PHY shall support the PHY Header as shown in Figure 114 [1]. This PHY Header is also mandatory for MR-FSK In MR-FSK: “All reserved fields shall be set to zero upon transmission and shall be ignored upon reception” R1-R0 are used by the ULP-GFSK PHY

  19. Reserved bits R1-R0: R1-R0 are used in the ULP-FSK PHY as follows: R0 = SPH Short PHR. When this bit is set while MS=”0”, the PHY Header (PHR) shown on the next slide shall be used. R1 = Rate When this bit is set the data rate across the PSDU shall be doubled by applying 4GFSK modulation as appose to 2GFSK which is used during SHR and PHR. One symbol rate is maintained across the entire PPDU and the outer deviation of the 4GFSK is equal to the 2GFSK deviation to support seamless transition from PHR in 2GFSK to PSDU in 4GFSK. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  20. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Short PHR: In addition to the mandatory PHR the Short PHR as shown below may be supported. The SHR does not support Mode Switching PHR as described in section 18.1.1.4 [1] The short PHR supports packet lengths up to 32 Bytes. Rate Rate 32 Bytes

  21. Specification of MS/SPH and Rate: Note: The Rate bit shall be ignored when 4(G)FSK is used across the entire PPDU. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  22. Modulation:= also used in MR_FSK Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  23. Modulation (cont.): Note: Operating Mode 16 is compatible to Bluetooth LE Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  24. Eye pattern - zero crossing and deviation tolerance spec: Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell 2GFSK h=1 4GFSK h=1/3 Same as MR-FSK

  25. Optional Precoding (1): Ordinary GMSK (i.e. GFSK with modulation index 0.5) modulation results in a differential encoding of the data BER performance is suboptimal due to error propagation A (optional) differential precoding of the input data is proposed to cancel that disadvantage: Coherent decoding of a precoded MSK signal yields optimal BER results Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  26. Optional Precoding (2): Precoding algorithm is already defined in [1] in section 18.3.2.8 as Bit Differential Encoding (BDE) and in [4] in section 11.2.3 as Differential Encoding Only for O-QPSK Phy [1] and BPSK [4] SFD und Preamble are precoded as well as the payload bit-stream Example: 2 octetpreamble + 2 octet SFD Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  27. ULP-GFSK in 12.5kHz channels: Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  28. ULP-GFSK in 25kHz channels: Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  29. ULP-GFSK in 200 – 400 kHz channels (1): Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  30. ULP-GFSK in 200 – 400 kHz channels (2): Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  31. ULP-GFSK in 1MHz channels: Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  32. ULP-GFSK in 500-2000 kHz channels: Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  33. ULP-GFSK in 500-2000 kHz channels cont.: Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  34. Radio frequency tolerance, same as in MR-FSK [1]: Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell 30 20

  35. Leveraging MR-FSK [1]: The ULP-GFSK PHY is using identical specifications for: Bit to Symbol Mapping Modulation quality Zero crossing tolerance Forward Error Correction (for convolution coding mode with K=4) Symbol interleaving Data Whitening RF specification Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  36. MAC Layer Features: ULP devices are recommended to use the multipurpose frame from IEEE 802.15.4e amendment Maximum freedom for system designer in deciding which header fields are absolutely necessary (MHR size can be reduced to absolute minimum) Each saved bit is saved energy In case of leveraging asymmetric link properties the beacon frame shall carry a header IE in order to signal which decoding methods are supported by the receiver (i.e. the concentrator) phyGMSKPrecoding: Boolean variable to indicate the ability to receive precoded MSK signals phySupportedFEC: Enumeration to indicate the supported FEC coding schemes Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  37. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Evaluation of ULP-GFSK PHY proposal

  38. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell PSDU efficiency: Definition used here: Where: Ttotal = total transmit on time TPSDU = time of PSDU transmission Notes: - ULP-GFSK PHY with 2 Byte preamble, 2 Byte Sync, Short PHR for 5 Byte PSDU - A 5 Byte PDSU  acknowledgement frame PSDU ULP-GFSK PHY has higher PSDU efficiency than TOOK

  39. Double Data Rate: PPDU example with 18 Byte PSDU: DDR bit not set: DDR bit set: Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Symbols: 16 16 8 144 P S H PSDU Symbols: 16 16 8 72 P S H PSDU Modulation = 2GFSK Modulation = 4GFSK

  40. PSD: Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell PSD of 4GFSK@h=1/3 is very similar to 2GFSK@h=1

  41. Spectral efficiency: Definition: 2GFSK  ηSA = 0.48 (bits/s/Hz) 4GFSK  ηSA = 1.09 (bits/s/Hz) Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Allows for short packets when BW constrained

  42. 20 dB signal Bandwidth: Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  43. Eb/No in AWGN for 2/4GFSK: Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell 1% PER

  44. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell BER simulation using channel model 15-13-0742-01:

  45. PER simulation using channel model 15-13-0742-01: For coherent GMSK demodulator Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell

  46. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell PER vsEb/No in AWGN – 2GFSK h=1:

  47. Eb/No in AWGN for GMSK: Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Note: Performance curves apply for a coherent demodulator

  48. Eb/No in AWGN for GMSK: Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Note: Performance curves apply for a coherent demodulator

  49. Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell Frequency tolerance:

  50. Sync performance in AWGN: Henk de Ruijter, Frederik Beer, Steve Jillings, Rick Powell