DAA Framework for UWB

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [DAA framework for UWB] Date Submitted: [March, 2006] Source: [Bin Zhen, Huan-Bang Li and Ryuji Kohno; Company: National Institute of Information and Communications Technology ] Contact: Bin Zhen Voice:+81 46 847 5445, E-Mail: zhen.bin@nict.go.jp] Abstract: [DAA framework.] Purpose: [UWB DAA support] 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. DAA framework for UWB by Bin Zhen, Huan-bang Li and Ryuji Kohno

3. Agenda for discussion in DOC. 06-0049-00-4a Regulatory requirement is to ensure coexistence by reasonable interference reduction technology, e.g. DAA, LDC. • Regulatory issues • (1) Necessity of Interference reduction technology, e.g. DAA • (2) Introduction and discussion of feasible DAA • Doc.06-00133-00-4a (This Doc.) • (3) Summary of issues in DAA for regulatory compliance • 2.Coexistence issues • (1) Category of coexistence problem • (2) Solution for regulatory requirement, i.e. simple DAA, LDC • (3) Definition of LDC: necessary duty cycle in node & PCN etc • Doc.06-00134-00-4a (Next Doc.)

4. PNC node node PNC Feasible DAA with Detect in PHY and Avoid in MAC in DOC. 06-0049-00-4a victim system b1 b2 b3 frequency without DAA with DAA victim system victim system interference no interference PNC should support a detection (e.g., energy) functionality. band allocation (b1,b2, or b3 ) band allocation (b2 or b3) Channel b1 is not assigned. Without DAA, the UWB and victim system will interfere with each other. The ranging mode of UWB requesting high SINR.

5. DAA in 802.15.4a • 15.4a defined basic request/report mechanism to provide a DAA tunnel (06-0047, Joe Decuir and 06-0049, Kohno, Hara, & Takizawa) • Interference measurement is only mandatory for FFD • Interference information communication between FFD and coordinator • Interference avoid command from coordinator • Victim detection mechanism (as per 802.11h) • Energy detection • Receive power indication histogram • CCA • Not consider the difference between 4a and 11h

6. Framework of DAA • Distributed sensing • Only FFD is required to conduct detection • Multiple clusters with FFD’s in a Piconet • Centralized decision at coordinator Victim report Cluster 2 Cluster 1 Avoidance command Cluster 3 PAN coordinator FFD, cluster header PICONET RFD, device

7. Geometry of DAA sensing border Protection range keep-out range UWB transmitter d Victim transmitter Victim receiver interference range

8. Geometry of DAA (cont.) • Protection range • where victim signal is much stronger than the noise interference introduced by UWB • Interference range • where victim signal is comparable with the noise interference introduced by UWB and some performance decrease can be find • Keep-out range • where severe victim performance decrease can be find

9. Implications to DAA sensing • The UWB interference depends on distance between victim transmitter and receiver • No problem if victim receiver is in victim dominated range • UWB transmitter should be out of the keep-out range • DAA sensing range should be larger than keep-out range • Victim-dependent range size • At least two-looks for transmission from transmitter and receiver • it is hard for simple sensor to separate them without decoding the packets

10. Detection dependent upon victim type • Classification of victim systems: from modulation • DS style • 3a-like MBOA, 3a-like DS-UWB and 4a • OFDM style • 3a-like MBOA, WiMax (16a), and Japan 4G • Radar? • Classification of victim systems: from bandwidth • UWB • Narrow band

11. Key issues in DAA sensing • You cannot see the full victim signal • Intersected and versatile channel bands • Feature based sensing cannot be used. Only energy based sensing is possible • Different channel busy patterns • Transient pulse energy filled with noise (<0.1 μs) • Symbol duration of channel busy time (100 μs) • Simple sensor nodes • Computing capacity, complexity, cost, power consumption • Almost no time limitation

12. Key issues in DAA sensing (cont.) 16a (10/20 MHz) Partially overlapped channels MBOA (4488MHz, 528MHz) f 4a (4446Mhz, 499.2MHz) Channel state pattern 4a (<0.1μs) 16a (>10μs, OFDM) MBOA (~0.3μs, FH) t

13. Expected DAA performance • DAA increases probability of interference among 4a piconets due to less available channels • Distributed DAA sensing • Pd=0.9 with Pfa=0.1of a FFD • the pionet detection probability is 0.9, 0.99, 0.999,… when there are 1, 2, 3, … FFD in the piconet;

14. DAA sensing mechanism • Split a 4a channel into sub-bands • 4a channels and victim channels are not full overlapped • Noise signal could dominate channel energy for a narrow band system, especially in low SNR environment. • Given 500MHz filter for a 20MHz signal, the noise level increase 14dB • Separated band-pass filter bank • 10MHz BPF bank for narrow band victims • 100MHz BPF bank for UWB victims

15. DAA sensing mechanism (cont.) • Victim dependent energy detection in both time and frequency domain • Time pattern of energy detection • Frequency hopping MBOA • Post-processing • Average, integration, etc. • Step-by-step sensing • Victim, sub-band

16. Block diagram of DAA 500MHz BPF Communication & ranging Matched filer De-spreader 100MHz tunable BPF Energy Detection Post- processing DAA decision 500MHz BPF (detected channel) 10MHz tunable BPF

17. DAA sensing performance • Impact factors of sensing • Filter bank • Filter bandwidth • Filter center frequency • Distribution of filter • Detection duration • Multipath channel • SNR • Central decision • Sub-band state decision at FFD • Merge algorithm at coordinator

18. Extension of basic request/report • Basic request • inform victim style • Basic report • Split a channel into sub-bands • Report busy probability of each sub-band • The same channel energy could indicate different states • Channel energy report is a big traffic • More than one victim systems in the same channel, e.g. 16a and MBOA.

19. New basic request/report format (06-0046 from Joe.) Basic request Channel number Measurement duration Channel number Victim style Measurement duration Basic report Channel number Channel energy Map field MBOA-UWB DS-UWB Narrow-band OFDM Radar signal Un-measured Sub-channel number Channel number Busy probability

20. TBD parameters • Busy sub-band sensing • Energy threshold • Time pattern • Optimal filter bank • Center frequency • Filter bandwidth • Filter distribution and density

21. Summary • Framework of distributed UWB DAA sensing • DS-UWB style and OFDM style • Split a 4a channel into sub-bands for DAA sensing • 100MHz for UWB victims • 10MHz for narrow band victims • Extension of basic request/report • Busy probability of sub-band • Simple DAA can be accomplished in a sensor node

22. Annex 1: UWB victim systems • 802.16a • OFDM receiver threshold: -90 dBm • Unlicensed channel: 10/20 MHz, 256 bands • Downlink pilot: 0xfff • MBOA • Mult-band OFDM receiver threshold: -80 dBm • Channel: 528MHz, 122 bands • Preamble: …. • DS-UWB • 3a-like • receiver threshold: -90 dBm • Channel: 3.1~4.9 GHz • Preamble: ….. • Japan 4G:

23. Annex 2: DAA in UWB and spectrum sensing in 802.22 • 802.22: a developing cognitive radio-based PHY/MAC standard in TV channels • Existing and narrow band systems • No channel intersection issue • Not handhold device and sensor