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: [Example UWB Tx Data] Date Submitted: [15−November−2006] Source: [Michael Mc Laughlin] Company [Decawave Ltd.] Address [25 Meadowfield, Sandyford, Dublin 18, Ireland] Voice:[+353−87-688-2514 ], FAX: [What’s a FAX?], E−Mail: [michael@decawave.com] Re: [802.15.4a.] Abstract: [Examines anomalies thrown up by trying to modulate some example data with the UWB radio] Purpose: [To promote discussion in 802.15.4a.] 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. Mc Laughlin, Decawave

2. Example UWB transmit Annex • Matlab Function to encode example UWB data according to Draft 5 • Followed the instructions unless there seemed to be an error • Came across places which need • Fixes for errors • Clarifications Mc Laughlin, Decawave

3. Input and Output • Input datafrom MAC • UWB welcomes IEEE • Intermediate data checkpoints Mc Laughlin, Decawave

4. Scrambler • In Table 39h it’s confusing that the scrambler initialiser and the scrambler output are in opposite order. • In Table 39h there are 16 bits in the Initial state table but they are assigned to 15 things (s-1 to s-15). • Need to delete one of the ones. • Because the scrambler initialiser is nearly all ones, the first 4 hopping positions in a frame will always be zero. • Don’t know if this is really bad, but don’t like it. • Because the scrambler initialiser is nearly all ones, the first 6 symbols are heavily DC biased. • Don’t like this one at all. • TG4a packets can be very short. This can be a significant part of them. Mc Laughlin, Decawave

5. Convolutional Coding • In 6.8a.9.2, the convolutional encoder must be initialised to [0 0]; • In 6.8a.9.2, there will be a performance loss unless the first systematic and parity bits are transmitted, • I can’t find any text which says that tail bits are added. I’ve added two, but I’m open to proposals for more Mc Laughlin, Decawave

6. RS Encoder • 6.8a.9.1, Page 76, Line 14 should be k=0 to 54 and not k=1:54 • Confirmed with Ismail that Eqn 6.8a.9.1, Page 76, Line 46 should be: U(x) = x8D(x) + P(x) and not U(x) = D(x) + x8P(x) Mc Laughlin, Decawave

7. Time Hopping • In section 6.8a.8.2 What happens to the h(k) if there are not enough bits in Ncpb to make a new burst position, i .e. Ncpb<m. Does it re-use the older ones? I think it implies yes. Should say this explicitly e.g. we say: “Note that this implies that if Ncpb < m, then some scrambler output bits get reused for h(k), albeit in a different bit position, i.e. using a different binary multiplier.” • In section 6.8a.8.2 page 74, m= log2(#Hopping Bursts), but table 39a uses Nhop so this would be much clearer if it said m= log2(#Nhop). Mc Laughlin, Decawave

8. Consistent Terminology • Figures 27i and 27k use c0 and c1 for the convolutional coder output, everywhere else uses g0, g1. Should make this consistent. • Tchip is used in Fig27c , Tc other places. • Reference to dump bits in 6.8a.9.1 Reed-Solomon encoder. Should this be dummy bits? Mc Laughlin, Decawave

9. Conclusions • Some errors found • Some editorial changes required • Do we need sponsor comments to hang each of these on? Mc Laughlin, Decawave