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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPAN’s)

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPAN’s) Submission Title: [Reasons to vote for the MB-OFDM proposal] Date Submitted: [July, 2004 Source: [Michael Mc Laughlin] Company [decaWave Ltd] Address [8133 Leesburg Pike Vienna, VA USA]

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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPAN’s)

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  1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPAN’s) Submission Title: [Reasons to vote for the MB-OFDM proposal] Date Submitted: [July, 2004 Source: [Michael Mc Laughlin] Company [decaWave Ltd] Address [8133 Leesburg Pike Vienna, VA USA] Voice:[703-269-3000], E-Mail:[michael@decawave.com] Re: Abstract: [Examines the five most popular reasons for voting for the MB-OFDM PHY proposal and finds that they are actually reasons to vote for the DS-UWB proposal.] Purpose: [Provide technical information to the TG3a voters regarding PHY proposals.] 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. Michael Mc Laughlin, decaWave

  2. Summary of reasons why someone might vote for MB-OFDM instead of DS-UWB 5. Complexity: MB-OFDM < 4 x DS-UWB. 4. Power: MB-OFDM < 4 x DS-UWB. 3. Range: MB-OFDM almost as good as DS-UWB on many channels. 2. OFDM previously chosen for other, different modulation schemes. 1. MB-OFDM is backed by TI / Intel /Sony /Philips and others. Michael Mc Laughlin, decaWave

  3. Reason 5: Complexity • MB-OFDM Digital Complexity less than 4 times DS-UWB Digital Complexity • Digital complexity of MB-OFDM is between 2 and 4 times that of DS-UWB depending on bit rate • True, but then why not choose lower complexity proposal Michael Mc Laughlin, decaWave

  4. Reason 5: Complexity Michael Mc Laughlin, decaWave

  5. Reason 4: Power Consumption • MB-OFDM Power less than 4 times DS-UWB Power • Digital power consumption at a given speed is proportional to the number of gates • MB-OFDM proposal is 2 to 4 times digital complexity complexity for same speed => digital power consumption of MB-OFDM is between 2 and 4 times that of DS-UWB. • True, so why not vote for lower power proposal Michael Mc Laughlin, decaWave

  6. Reason 4: Power Consumption Michael Mc Laughlin, decaWave

  7. Reason 3: Range • MB-OFDM range is almost as good as DS-UWB on many channels • Almost is not good enough. • It is true that MB-OFDM ranges come fairly close to DS-UWB for the 110Mbps mode, but as conditions get worse and as bit rates rise, the DS-UWB advantage increases. • e.g. DS-UWB outstrips MB-OFDM by more than 60% for the 220/200Mbps over CM4. Michael Mc Laughlin, decaWave

  8. Reason 3: Range Michael Mc Laughlin, decaWave

  9. Reason 2: OFDM used in other standards • OFDM modulation has previously been chosen for other differentmodulation schemes. • True, e.g. ADSL and 802.11 butthe key word here is different. • In ADSL the fixed channel allows the number of bits per tone to be varied according to SNR for that part of the channel. This is not currently possible for wireless systems. • In 802.11a/g the SNR assumed is very high compared to UWB and the bandwidth is much lower. • For both of these reasons, the rayleigh fading effects are far less damaging. And it’s a big but Michael Mc Laughlin, decaWave

  10. Reason 1: Many large companies support MB-OFDM • Giants like Intel/Philips etc. wouldn’t pick an inferior scheme, right? • Wrong! They already admitted this when they abandoned their original Multiband proposal in favour of TI’s MB-OFDM proposal Michael Mc Laughlin, decaWave

  11. Summary • The five top reasons for voting for MB-OFDM have examined and found to actually be reasons to vote for DS-UWB • This is without even considering the obvious reasons not to vote for MB-OFDM (Interference, SOP performance, Time to Market, Scalability) • There are no good technical reasons to vote for the MB-OFDM proposal. Michael Mc Laughlin, decaWave

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