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

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Suggested revisions for T/TR comments regarding CCA issues (Part 1)] Date Submitted: [February 8, 2006] Source: [Yihong Qi, Bin Zhen, Huan-Bang Li, Shinsuke Hara and Ryuji Kohno Company: National Institute of Information and Communications Technology ] Contact: Yihong Qi Voice:+81 46 847 5092, E-Mail: yhqi@nict.go.jp] Abstract: [Suggested revisions for T/TR comments regarding CCA with multiplexed preamble are presented.] Purpose: [Help to resolve the T/TR comments on CCA issues] 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. Suggested Revisions for T/TR Comments regarding CCA issues (Part 1) Yihong Qi, Bin Zhen, Huan-Bang Li, Shinsuke Hara and Ryuji Kohno National Institute of Information and Communications Technology (NICT)

3. Classification of the comments on CCA • T/TR comments on • clause 6.8a2.1: description of the multiplexed preamble (10, to be addressed in this presentation) • clause 6.9.9: CCA modes (to be completed soon) • E comments (3, all accepted)

4. Comment 423 (TR) • Comment The figure shows two blocks for the Frame Length, implying that the field is repeated twice (all 7 bits) • Suggested remedy This should be the 4 lsbs of the Frame Length in the left most block the 3 msbs of the Frame Length field and the reserved bit in the next block over.

5. Suggested revision for C423 • This is what we mean to be. For clarity, the label ``frame length” is changed to be ``frame length segment”, as Revised part

6. Comment 424 (TR) • Comment What is the "mandatory setting” on pp. 28, line 35 • Suggested remedy Define the "mandatory setting" clearly, perhaps with an xref to where it is defined.

7. Suggested revision for C424 • The comment is accepted. The sentence is revised as ``The modulation and the waveform of the inserted preamble symbols are defined in 6.8a.2 and 6.8a.3.”

8. Comment 425 (TR) • Comment pp. 28, line 35 The numPSDUBits is only defined for when the mandatory data rate is used. There is no information for what to use for the other data rates. • Suggested remedy Define numPSDUBits for the other data rates.

9. Suggested revision for C425 • The time interval between two adjacent inserted preamble symbols is fixed (for both mandatory and optional data rates), and is defined according to the mandatory data rate. To be specific, the corresponding sentence is revised as ``The time interval between two adjacent inserted preamble symbols is fixed, and is equivalent to the duration of 4 mandatory symbol lengths. The mandatory symbol rate is 0.965MHz, as defined in 6.8a.3.1.”

10. Comment 426 (TR) • Comment pp. 28, line 41 You can't guarantee that the CCA detector will find the preamble symbols, it depends on the signal level, channel quality and interferers, if any.. • Suggested remedy Change "shall find at least" to be "will have the opportunity to find at least“ • Comment accepted

11. Comment 427 (TR) • Comment pp. 29, line 6 (first line of the second paragraph) I think you mean "command frame" not "MAC frame" • Suggested remedy Change "MAC frame" to be "command frame“ • Comment accepted

12. Comment 428 (TR) • Comment pp. 29, line 12 (the third paragraph) Otherwise, the PHY is supposed to look for the preamble symbols, not report the medium idle. It only reports idle if it doesn't find the preamble symbols. • Suggested remedy Change the text to correctly describe the CCA process.

13. Suggested revision for C428 • The comment is accepted. The sentences are revised as ``In the optional UWB CCA mode, the PHY shall listen to the medium during a period equivalent to the CCA detection window. If the preamble symbol is detected, the CCA shall report a busy medium. Otherwise, an idle medium shall be reported.”

14. Comment 490 (T) • Comment pp. 29, line 12 (the third paragraph) The second to last paragraph in this section says, "Otherwise, an idle medium shall be reported". This sounds appropriate for mandatory ALOHA mode, but not for any other CCA mode. • Suggested remedy Clarify text. • Comment accepted. Similar comment to C428

15. Comment 678 (T) • Comment pp. 28, line 28 (the third paragraph of 6.8a2.1) It is not clear to me how long the interleaved preamble segments should be. Figure 27b says "Preamble symbol" Does this mean one transmission one period of the preamble code? Later on in the text we have the following: "Wherever the CCA detection window starts, either from the regular preamble or from the data portion in a frame, the CCA detectors shall find at least 8 preamble symbols in the CCA detection window" How do we ensure this to be true. I'm thinking of small packets with very little payload? • Suggested remedy Clarify the meaning of "Preamble Symbol" in terms of it length.

16. Suggested revision for C678 • The meaning of ``preamble symbol” is clarified as ``The inserted preamble symbol shall be same as the preamble symbol used in the preamble field of the same frame, as defined in 6.8a.2.”

17. Comment 702 (T) • Comment In addition to facilitate the CCA function, the multiplexed preamble can be used to improve the accuracy of ranging and/or channel estimation, in a similar way to the pilot aided tone adopted in narrowband systems. For instance, for the fast ranging with the preamble length of 256 symbols and the multiplexed preamble of 64 symbols (time-interleaved with PSDU of 256 bits), the accuracy improvement is estimated to be 70%. • Suggested remedy such usage of multiplexed preamble should be mentioned in this section. • Comment accepted

18. Concluding Remarks • The revised suggestions for the comments regarding description of the multiplexed preamble are presented. • If the suggestions are acceptable, we are going to modify clause 6.8a.2.1 to incorporate those changes. The modified text will be sent to the web server soon. • Revisions corresponding to the remaining comments are to be presented next time.