1. doc.: IEEE 802.15-04/080r0 Submission February 2004 Welborn, MotorolaSlide 1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Compromise for UWB Interoperability – MAC Overview] Date Submitted: [20 February, 2004] Source: [Matt Welborn] Company [Motorola, Inc] Address [8133 Leesburg Pike] Voice:[703-269-3000], FAX: [703-249-3092], E-Mail:[mwelborn@xtremespectrum.com] Re: [IEEE 802.15.3a Call For Intent to Present for Ad-Hoc Meeting] Abstract:[This document provides an overview of a proposed Common Signaling Mode that would allow the inter-operation or MB-OFDM and DS-UWB devices.] Purpose:[Promote further discussion and compromise activities to advance the development of the TG3a Higher rate 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. doc.: IEEE 802.15-04/080r0 Submission February 2004 Welborn, MotorolaSlide 2 MB-OFDM & DS-UWB Interoperability Past TG3a deliberations have focused on choosing one solution of the two remaining – either MB-OFDM or DS-UWB Another solution is to choose both: –The 802.15.3 MAC is a TDMA MAC and uses central control to assign time slots for use by individual devices –This TDMA behavior can serve as the basis for the two fundamentally different classes of UWB devices to interoperate while using the 15.3 MAC Once a device is assigned a timeslot, that slot can be used for either MB-OFDM or DS-UWB transmissions, as the device chooses The basic mechanism needed to make this work is a “common language” or common signaling mode (CSM) that allows MB- OFDM and DS-USB devices to communicate at some basic level to allow time slot request and allocations

3. doc.: IEEE 802.15-04/080r0 Submission February 2004 Welborn, MotorolaSlide 3 Talking with each other: Basic Requirements Each class of UWB devices (MB-OFDM or DS-UWB) needs a way to send messages to the other type –MB-OFDM  DS-UWB –DS-UWB  MB-OFDM Even better, design a common signaling mode that can be understood by either class of devices Goal: Minimize additional complexity for each type of device while enabling this extra form of communications –Use existing RF components & DSP blocks to transmit message to “other-class” devices –Also need to support a low-complexity receiver –Lower rate mode could be acceptable if it can be used to provide robust control functions

4. doc.: IEEE 802.15-04/080r0 Submission February 2004 Welborn, MotorolaSlide 4 MB-OFDM & DS-UWB Interoperability Beacon (CSM) MB-OFDM Slot DS-UWB Slot Super-frame CSM would be used for beacon in default mode –Also for control frames between dissimilar class devices CSM could also be used for data exchange in assigned time slots between different class devices CSM needs to be of sufficient data rate to cause minimal impact to overhead CSM Slot

5. doc.: IEEE 802.15-04/080r0 Submission February 2004 Welborn, MotorolaSlide 5 Overhead of a Slower Beacon for Superframe Assume a heavily loaded piconet: 100 information elements in beacon “Fast” 15.3a beacon overhead with 100 IEs (e.g. CTAs) @ 55 Mbps (15 us preamble + 107 us payload + 10 us SIFS) / 65 ms = 0.2 % CSM beacon overhead, assume 100 IEs (e.g. CTAs) @ 9.2 Mbps (50 us preamble + 643 us payload + 10 us SIFS) / 65 ms = 1.1 % Overhead (as a percent) would be higher for shorter superframe duration Conclusion: Slower beacon data rates can lead to acceptable increase in beacon overhead (Too slow? at 1 Mbps, overhead grows to ~10%) Beacon Preamble SIFS Beacon Payload Total Beacon Overhead Total Superframe Duration (65 ms) Other Traffic

6. doc.: IEEE 802.15-04/080r0 Submission February 2004 Welborn, MotorolaSlide 6 Other MAC Issues CSM simply becomes a required data rate “mode” for both classes of devices –Higher data rates (110, 200) are also required, but can be implemented in device for either MB-OFDM or DS-UWB (or both) PNC records DEV capabilities –MB-OFDM or DS-UWB or both –Also announced to other DEVs in piconet CSM used for beacon and control traffic when required –Used for MCTA traffic between dissimilar devices –Similar devices (DEV/PNC pair) negotiate CMS or native mode for MCTA CSM can also be used for data traffic between dissimilar devices during assigned CTAs

7. doc.: IEEE 802.15-04/080r0 Submission February 2004 Welborn, MotorolaSlide 7 Conclusions The creation of a common signaling mode will allow co- existence and interoperability between DS-UWB and MB-OFDM devices Minimum useful data rate for 15.3 MAC-based interoperability is ~10 Mbps A Common Signaling Mode is described that: –Provides interoperability in a shared piconet environment –Prevents coexistence problems for two different UWB PHYs –Requires minimal additional cost/complexity in MB-OFDM & DS- UWB Almost no additional complexity for transmit Multiple options for receive using either time or frequency domain DSP blocks in MB-OFDM radio –Can achieve desired data rates and robust performance