Project: IEEE 802.15 Working Group for Wireless Personal Area Networks (WPANs)

1. Project: IEEE 802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [TG4a Comment Resolution – Regulations and Framework] Date Submitted: [March 2006] Source: [Matt Welborn] Company [Freescale Semiconductor, Inc] Address [8133 Leesburg Pike Vienna, VA USA] Voice:[703-269-3000], E-Mail:[matt.welborn @freescale.com] Re: [] Abstract: [] Purpose: [Provide framework for revision baseline draft] Notice: This document has been prepared to assist the IEEE 802.15. 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 802.15.

2. Regulatory Annex - Description and Purpose • Informative: “This annex provides informational references to and key summary of the more critical regulatory requirements, with analysis of the impact on the specifications and design of IEEE 802.15.4 products where appropriate. Due to the great breadth and variety of worldwide regulations it is not possible to cover all nations in the available time and space.” • Our situation: • UWB regulations exist only in the US, under the FCC • Other regions may or may not have rules before 2007 • Regulations will likely continue to change for years

3. Recommendation • Outline rules that are settled: FCC • Acknowledge situation worldwide as changing • Brief descriptions of potential outcomes in other regions • Don’t try to guess what will happen • Describe features we have provided in TG4a to deal with this situation • Helpful to reader • Responsive to “No” comments (about 20 T & TR)

4. Relevant Features of TG4a • Multiple bands and band group definitions • Support for different rules in different regions • Regulatory restrictions • Minimum bandwidth • Performance based on low PSD • Potential for LDC operation • Potential for data rate network topology requirements • Potential for transparent per-device control of spectrum • Mechanisms to support future network-based mitigation requirements • Compliance with specific regulations is enabled by the standard, but is still the responsibility of the implementer.

5. Responses to Comments: Worldwide Regulatory Support (~10 comments)

6. Response for DAA “This standard is likely not to be allowed for worldwide usage as it contains no provisions for operation in Asia or Europe. This system should incorporate detect and avoid measures to narrow-band incumbents.” Response: The current proposals for mitigation requirements are still being developed by regulators and seem to depend on future spectral allocations to other systems in some regions. The Committee has provided options to allow transparent per-device control of spectrum through pulse shaping. The Committee has also provided a basic mechanism to allow network-based mitigation under the control of the PNC. As the specifics of mitigation requirements (such as DAA) are still TBD, the details of this mechanism are considered implementation-dependent and are thus out-of-scope for this work. Overly-restrictive requirements would increase the complexity and cost of devices and are to be avoided.

7. Geographic Awareness “Based on the great diversity of regulations (or proposed regulations) on UWB, the TG4a implementors will have three choices:1) have multiple SKUs for different regulatory administrations, and constrain the distribution of each SKU geographically.2) ship ‘one-sized-fits-all’ devices. (As of last november, that looked like 7.25 – 9.0 GHz.)3) add simple geographic awareness, or functional equivalent, into the design as an option” Response: The Committee has provided enough options to allow the implementation to support either (1) or (2) above – regional or global applications based on our current understanding of potential regulations worldwide. Adding feature (3) is determined to be beyond the scope of the PAR at this time.

8. Response for LDC “Band plan and coexistence technology such as DAA or LDC may be included in the standard because Japanese and EU Regulations request them.” Response: The Committee has provided mandatory and option features to allow the implementation to support LDC operation. The use of shorter preambles and symbols can allow further reduced duty cycle operation. Coordination and enforcement of a potential LDC requirement is implementation-dependent and is therefore out-of-scope for work.

9. OOB Emission Limits • The frequency plan will not meet expected regulatory requirements for 4.2-4.8GHz without DAA in Europe, Japan, and Korea. • Make the frequency plan fall within 4.2-4.8GHz with suppression to -70dBm/MHz from 3.1-4.2GHz. Response: The OOB emission limits will likely vary in different regions and are therefore implementation dependent. Imposing unnecessarily low limits where not required would increase implementation complexity and cost.

10. Sub-GHz UWB Band Group • I know of no regulatory authority which allows UWB operation below 1 GHz. For example, per FCC rule 15.209, "Fundamental radiation from intentional radiators operating under this Section shall not be allowed in the bands 54-72 MHz, 76-88 MHz, 174-216 MHz and 470-806 MHz." The standard should not contain elements which cannot be implemented. Response: There are many regions that have yet to create initial UWB regulations and even the US has indicated that UWB regulations will likely be relaxed based on future deployment experience. There are precedents for exceptions to the Restricted Band regulations, for example the UWB rules themselves (47 CFR 15, sub-part F). The Committee has provided optional modes that could provide enhanced communications and ranging performance for evolving regulations or applications where commercial regulatory compliance is not essential.

11. Optional/Mandatory Bands • The channel allocations are not consistent with the PAR requirement for an "international" standard, based on the current proposals for Japan and EU. • Resolve conflicts with regulatory actions either by removing the channels which conflict, make those channels that conflict with some regulatory domains optional, amending the power limits, or other means to allow design of a 802.15.4a system which complies with regulatory requirements. Response: The Committee has revised the band structure to closely align with the 4.2-4.8 GHz band while reducing implementation complexity. Additionally, this has been made the default mandatory band for the lower band group. The Committee has also provided multiple band groups for regions with large differences in UWB spectrum, as well as a 2.4 GHz ISM band group for regions with no UWB spectrum allowance.

12. TG4a Overview • Responsive to PAR: Low complexity & power with precision ranging • Regulatory flexibility: Multiple bands in different band groups tailored to expected regulations around the world • Coexistence: Low PSD + low duty cycle + multiple bands + other features • Scalable performance vs. complexity: responsive to the wide range of proposed applications

13. Baseline Mode – Low Complexity with Robust Performance in Multipath • Single UWB band centered at ~4.5 GHz • Based on 499.2 MHz band spacing • Hybrid PPM+BPSK modulation • Default preamble • 64 symbols of L=31 perfect ternary sequence • Data rate: nominal 850 kb/s (851 kb/s) • Concatenated code • Systematic RS + Systematic convolutional code • Very low complexity Aloha medium access control • Ideal for low duty cycle UWB waveforms • Wide bandwidth (>500 MHz) for precision ranging

14. Spectrum Usage • Provides flexibility for coexistence and regulatory compliance worldwide • 4 band groups • 1: 3.1 to 4.8 GHz • 2: 6 to 10.6 GHz • 3: 2.4 ISM band (non-UWB  requires different modulation) • 4: 500 MHz • One or more designated operating frequencies within each band group • Each band group has a single mandatory band to minimize complexity while ensuring interoperability

15. Comments in “Framework” First, here is a summary list of some of the "sub-topics" within "Framework" category (w/ # of individual comments in each) - coexistence with other UWB (3) - too many modes or confusing (27) - incompleteness (10) - number precision (3) - operation of modes/rates (13) - sub-GHz mode (7) Others: (~1 each) - ranging, PRFs, preambles, packet size, chaos mode, FFD

16. 5.2.1 Network formation Add: Some channels have a single PHY mode defined. Some channels have s single mandatory mode but one or mode optional modes to provide additional flexibility Network formation always performed using mandatory mode to ensure reliable operation     Specific mechanisms are defined in XX.YY to allow one ore more devices to use option modes after initial formation 

17. 5.3.1 PHY List (add): 2400 CSS (Worldwide), UWB (Worldwide, varying by region) Text: LR-WPANS can operate in multiple independent band groups. A device can implement a single band or multiple bands, but in each band implemented must support the mandatory channel to ensure interoperability for devices that share a common band group. For UWB devices, there are three independent band groups: 500 MHz, 3.1-5 GHz and 6-10.6 GHz. Each has a single mandatory channel and devices in each band operate independently of the other bands. Devices in the three different UWB band groups use the same bandwidths and chipping rates to simplify design and implementation, with each band having different performance, coexistence, and regulatory characteristics.  The three different UWB band groups provide flexibility to allow LR-WPAN devices flexibility to operate in different regions as the UWB regulations are defined and updated over time. The UWB PHY also incorporates a number of optional enhancements to potentially improve performance, reduce power consumption, or enhance coexistence characteristics. These optional enhancements: • Do not compromise the existing LR-WPAN model that all devices operating in a common band group will always be able to interoperate with a single default mandatory mode • Do not raise the baseline complexity for compliant devices, but rather recognize that some applications or implementations may need enhanced performance or coexistence capabilities while still maintaining full interoperability, and • Provide the capability to UWB LR-WPAN devices to operate under a wider range of RF channel conditions while still providing robust performance and precision ranging Reference to sections that describe enhancement options and mechanisms for managing enhanced modes while ensuring interoperability

18. 5.4 Functional Overview add:   ... and ranging. 5.4.1 Superframe Structure 5.4.2 Data transfer model 5.4.2.1. add: ... or ALOHA, as appropriate... 5.4.2.2. add: ... or ALOHA, as appropriate... 5.4.2.3. add: ... or ALOHA, as appropriate... 5.4.3 Frame structure 5.4.4 Robustness 5.4.4.1 CSMA-CA Mechanism 5.4.4.1a  ALOHA protocol for the UWB PHY [text to be provided based on a modification of existing text in TG4a draft]

19. 5.4 Functional Overview (cont.) 5.4.4.2 Frame Acknowledgment 5.4.4.3 Data Verification 5.4.4.4 Enhanced Robustness Features for UWB PHY • Extremely wide bandwidth characteristics (UWB) that can provide very robust performance under harsh multipath and interference conditions • Concatenated forward error correction (FEC) system to provide flexible and robust performance under harsh multipath conditions  • Optional pulse control features that can potentially improved performance under some channel conditions while providing reliable communications and precision ranging capabilities 5.4.5    Power consumption considerations 5.4.5.1 Additional power consumption features provided by the UWB PHY • Hybrid modulation that allows for very simple receiver architectures to minimize power consumption and implementation complexity ... • Optional pulse control features that can potentially allow lower power consumption under some channel conditions ... • Optional shorter symbols and preambles that can allow reduced duty cycle operation for reduced power operation or for enhanced coexistence (when conditions allow)

20. 5.7 Coexistence 5.7.1. UWB band Coexistence  UWB bands operate in spectrum different from other PHY that use unlicensed spectrum.  Due to these special considerations, a number of extra features have been included with the UWB PHY design to support coexistence with other other spectrum users as well as with other UWB systems.     (1) Low PSD - compliant with regulations for UWB in different parts of the world, including low OOB emission requirements     (2) Multiple band groups and operating frequencies within each band - allows devices the option to avoid bands that might be in use or otherwise unavailable     (3) Optional modes to operate with shorter symbol timing to minimize emissions and channel occupancy when applications allow     (4) Specific commands that provide a basic framework to allow higher layers to control the radio for coexistence functions and possible interference mitigation     (5) Optional spectral control features based on pulse shaping to allow enhanced coexistence with other spectrum users   [Reference to CA document] 5.7.2 2400 MHz CSS band Coexistence [text + Reference to CA document]

21. Modulation and FEC • Extremely low complexity architectures are supported for key applications • Hybrid design to provide scalable complexity and performance • Combined PPM and convolutional coding to support coherent and non-coherent architectures • Provides robust performance even in extreme multipath environments • Systematic FEC codes to allow flexible decoding implementation

22. Back up slides

23. There are too many preamble/PRF combinations and the longer preambles are too long. The suggested regulatory actions in EU and Japan suggest some kind of mitigation in the bands 4a occupies. The most promising mitigation suggested for low bit rate UWB devices is the "low duty cycle" option (LDC) which is also the most feasible for 4a requirements for low complexity. The longer preambles < 1ms will make it unlikely that 4a will be able to comply with reasonably expected LDC specifications; the result could severely limit potential compliance with EU and Japan regulations and/or require active detect and avoid implementation, which greatly complicate the design of the device, compromising the PAR requirement for "ultra low cost, ultra low power".

24. Pulse Shaping • Pulse-based UWB technology allows the use of • Latitude in pulse shape allow implementation to optimize for different issues: • Control spectrum • Improve performance in different areas • Minimize complexity • Baseline pulse is specified • Additional optional modifications are identified • Composite pulse based on linear combination • Chirp & CS  intended to reduce cross-correlation • Phase incoherent pulse [was “chaos”]

25. Precision Ranging • Precision ranging capability is provided • MAC layer support: • PHY layer support: variable preamble lengths provided to support channel estimation and multipath correction • Ranging protocols

26. Scalability • Extreme multipath conditions • Reduced PRF for operation in extreme channels • High density deployments • Multiple codes per operating band • Time dithering for piconet isolation • High processing gain for isolation • Alternate symbol rates to trade off robustness and channel duty cycle