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1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks(WPANs) Submission Title: Benefits of ranging bit in PHY for TG4m ranging Date Submitted: Sept. 2012 Source:Mi-Kyung Oh, Jae-Hwan Kim, Jae-Young Kim, and Sangsung Choi (ETRI), Soo-Young Chang (SYCA) Contact: ohmik@etri.re.kr Voice:+82 42 860 6831, E-Mail: ohmik@etri.re.kr Re: Abstract: This contribution presents benefits of ranging bit in PHY for TG4m ranging Purpose: 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. Slide 1 ETRI

2. Outline • The goal of this document is to provide benefits of ranging bit in the PHY header for TG4m ranging • This document includes several examples to use the ranging bit in PHR ETRI

3. Issues on Ranging Bit • In addition to the ranging information request IE in the MAC frame, Doc. 473-01 suggested the ranging bit in PHR to indicate that the particular frame is intended for ranging • Do we really need the ranging bit in PHR? ETRI

4. Ranging Counter Overview • The complete two-way ranging exchange Early in time Later in time Data Payload PHR SHR Later in time Early in time Data Payload PHR SHR Start Start Tx Rx Rx Tx Ranging originator Ranging originator Ranging responder Ranging responder The ranging counter in the originator The ranging counter in the responder Stop Stop Early in time Later in time SHR PHR ACK Early in time Later in time SHR PHR ACK ETRI

5. Ranging Bit in PHY • The ranging bit itself does not cause any additional PHY overhead and any additional power consumption since one of reserved bits in PHR is used for the ranging bit • If there is any benefit of exploiting a ranging bit in PHY, it will be better to use the ranging bit • Since we already have well-developed UWB ranging standard in 15.4-2011, it will be better to keep consistency • 15.4a, PD-DATA.confirm & PD-DATA.indication primitives provide the parameter named RangingReceived which is determined by RNG from the received PHR ETRI

6. Benefits of Ranging Bit in PHY • The ranging bit in PHY enables efficient implementation of ranging operation at the receiver • Efficient on/off of ranging counter • Triggering a timing correction logic for enhancing accuracy • Reducing MAC overhead • There will be many approaches to use the ranging bit in PHY in the view of implementation ETRI

7. Ranging Counter Operation • Ranging bit in PHR can trigger the ranging counter in the receiver • The ranging counter can start its operation upon ranging bit arrival • Received RMARKER timing can be achieved due to fixed known timing offset between RMARKER and ranging bit • Therefore, the ranging counter does not need to run at every packet reception RMARKER Ranging Bit PHY Layer PHR PSDU SHR Fixed known offset ETRI

8. Timing Correction for Accuracy • Ranging bit in PHR can trigger a timing correction logic for ranging accuracy • Capturing the ranging counter value itself is not difficult • Timing correction should be carried out and applied to the captured ranging counter values • Clock frequency offset consideration • Some mechanisms for sub-sample accuracy • First path detection in multipath channel • In addition, it will help to selectively produce the ranging figure of merit (FoM) for the ranging frame to indicate ranging confidence level ETRI

9. Reducing MAC Overhead • Ranging bit in PHR can help reducing MAC overhead when ranging is enabled • During the ranging mode, there would be many normal data exchanges which are not intended for ranging • Reporting RangingReceived=0/1 to the MAC makes it easy to handle the ranging operation in the MAC ETRI

10. Conclusions • The ranging bit in PHY does not cause any additional PHY overhead and power consumption since one of reserved bits in PHR is used for the ranging bit • Benefits of the ranging bit in PHY • Triggering the ranging counter operation and efficient on/off of ranging counter • Triggering the timing correction logic and selectively producing FoM for the ranging frame • Reducing MAC overhead • and others… • The ranging bit in PHY will make our ranging capable TG4m PHY smart in the view of implementation ETRI