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: [Block based PHY and Packet Transmission for Low Data Rate In-body WBAN Date Submitted: [4 MAY 2009] Source: [Dong-Sun Kim1, Jong-Ik Song1, Tae-Ho Hwang1, Young-Hwan Kim1, Jae-Gi Son1, Sang-Jin Hyun1, Ha-Joong Chung1, Chang-Won Park1 and Yangmoon Yoon2] Company:[KETI1, KORPA2] Address : [KETI1 ; #68 Yatap-dong Bundang-gu, Seongnam-si, Gyeonggi-do 463-816, South Korea, KORPA2 ; 78 Garak-dong, Songpa-gu, Seoul, 138-803, South Korea] Voice: [+82-31-789-73841, +82-2-2142-21622], FAX: [+82-31-789-75591, +82-2-2142-21992] E-Mail: [dskim@keti.re.kr1, yoon001@paran.com2] Re: [] Abstract: Key requirements of the BAN standards effort, including power, cost and throughput scalability, can be addressed using a scalable block frame structure based on variable block FEC. In addition, BCH encoded 2FSK modulation scheme enable simple structure, low power consumptions and low cost transceiver implementation under in-body communication channel. Purpose: This document is intended as a proposal for addressing the requirements of the TG6 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. Contributors KETI : Korea Electronics Technology Institute KORPA : Korea Radio Promotion Agency

3. Presentation Outline Applicationsfor low data-rate in-body WBAN Topology for Implantable Devices Regulations for 400MHz MICS Comparison of Modulations Design objective and Physical layer Functions Data Rate and Modulation for In-body Communication Proposed MAC architecture and Frame Structure Extended MAC Protocol based on proposed PHY Performance and Conclusion Reference

4. Applicationsfor Implantable BAN • Deep Brain Stimulator • Implantable Cardioverter Defibrillator • Pacemaker • Drug-Delivery Applications for Low-data-rateIn-body WBAN

5. Topology for Implantable Devices • Maximum Number of Nodes • Under 10 Nodes in 2m (Address: 232 Nodes) • Star Topology • Indirect Transmission • Broadcast • Multi-hop Link D0 Wakeup D3 D2 C Wakeup C D Data Wakeup Data [Indirect Transmission] [Coordinator / Device] D1

6. Regulations for 400MHz MICS • International Reference • ITU-R SA 1346, Sharing between the Meteorological Aids Service and Medical Implant Communications Systems(MICS) operating in the Mobile Service in the Frequency Band 401-406MHz • US standards • US FCC Regulations, available from www.fcc.gov : • 47CFR95.628 • FCC add adjacent spectrum(401~402 & 405~406 MHz) for MICS March 19, 2009, By report and order(FCC09-23)

7. Why FSK? • Bandwidth & power limited system • Error probability of BPSK • Error probability of 2FSK GFSK 300 KHz -20 dBC 2FSK Power limited : Using 2FSK instead of BPSK BW limited : Using GFSK instead of 2FSK

8. Why not M-ary FSK? • Simulation results under channel model 2 • BPSK, 2FSK, 4FSK • System configuration • CM2 400MHz Path Loss model • 10cm away from the body surface, FSPL can be added to CM2. • link budget • Carrier Frequency : 403.5MHz • BW : 300kHz • MCS • 2FSK – coherent / non-coherent • BPSK – hard decision • 4FSK – coherent / non-coherent • Noise Figure : 5dB • HW loss margin : 5dB • Thermal noise : -119.229dBm • Tx power : 25μW • Antenna Gain : 0dB

9. Why FEC? • Forward Error Correction (FEC) is a system meant to minimize the amount of digital data lost on transfer. • Additional methods to diminish error-rates are ARQ, and Data Carousel, that are sometimes used together with FEC. • Does not require a back-channel (as opposed to ARQ). Therefore, an excellent solution for multicast of medical information such as ECG. k bits or symbols Data block FEC encoding n Data Redundant k n-k

10. Channel description & System performance Performance assessment of different MCS Comparisons of BCH and RS 1) Coherent Rx and CM [2] 2) Reference: [1] – [7]

11. Design Objective and Proposed Physical Layer Functions For In-body WBAN • Design objective • Scalable packet size • Advantage : In highly attenuated in-body model, scalable block based transmission would be better than fixed packet based transmission. • Bitmap based data-block management • High reliability • Header : 16byte, BCH(128,120) • Data : variable block length (Max block FEC: BCH(255,247)) • Error control flow using block map based frame structure. • Power and Bandwidth efficiency modulation • Modulation and Functions

12. ProposedData Rate and Modulation • Power efficient FSK Modulation • Band limited gaussian pulse shape filter • Improve spectrum efficiency at the cost of increased ISI • Cause elevated BER compared with a typical FSK • FEC for compensating the elevated BER • Extended Binary Primitive BCH Codes • 500 kbps is a minimum transmission data rate for 8bit RGB 256x256 pixel color image with 1 fps and 4:1 image compression ratio • JPEG compression ratio is typically 4:1 for CT and MR. • 32 channel ECG need minimum 192 kbps and 2 channel EMG needs 256 kbps.

13. Proposed In-body MAC Architecture • Use IEEE 802.15.4 MAC and Extend Primitives • Primitives for Block based Error control • Extended Primitives make common MAC frame if errors exist (IEEE 802.15.6) (IEEE 802.15.6)

14. MAC Channel Access • Coordinator must do CCA each channel before transmitting to a in-body device • CCA each channel over 10 ms • Data transmission • Block map based transmission • Binary Sequencing • 1bit Flow Control • Frame pending or stop transmission • 48bit address information • 16bit BAN ID, 32bit transceiver ID

15. Error Control Frame Structure 6 • Header FEC for implantable devices • 32bit Bitmap Block for 32 data blocks • 16bit Ban ID : Medical Service ID • 32bit Transceiver ID : 232 = 4G • Scalable Block Size : • - Number of bits in Block : 8/16/32/64/128/256

16. Retransmission Mechanism

17. Flow Control

18. Simulation Result (1) • PER comparison of variable packet size • Variable packet sizes are not issue under CM2 Channel • Block size depend on sending data size and variable block size reduced the zero padding bit for FEC

19. Simulation Result (2) • Transmission efficiency • The Efficiency R is given by [11] • N :block message • B : the number of bits per block • L : information bits • H : message header Performance : BCH + Retransmission > Convolution Code > without FEC Complexity : Convolution Code > BCH + Retransmission > without FEC

20. Conclusion • Transceiver with error control enabled scalable frame block decreases retransmission packet size and increases duty efficiency • Use 2FSK combinedwith block FEC at low data rate to let simple receiver structure and implementation • This presentation introduceskey scheme to be applicable to a standard of WBAN

21. Reference • Kamya Yekeh Yazdandoost and Ryuji Kohno, “Channel Model for Body Area Network(BAN)”, 802.15-08-0780-09-0006, April 2009 • Sukor.M, Ariffin.S, , “Performance Study of Wireless Body Area Network in Medical Environment,” Second Asia International Conference on, 2008 • doc. IEEE 802.15- 08-0-00-0006 • doc. IEEE 802.15-08-0689-00-0006 • B. Sklar, “Digital Communications 2nd Edition,” Prentice Hall. / A. Goldsmith, “Wireless Communications,” stanford university. • “Reed-Solomon codes for land mobile satellite channels,” Elec. letters, 15th Aug. 1991, vol. 27. No. 17 • J.A. Heller and I.M.Jacobs,”Viterbi Decoding For Satellite and Space Communication,” IEEE Trans. Commun.Technol., vol. COM19, no.5, October 1971, Fig.7, p. 84 ⓒ1971 IEEE • FCC add adjacent spectrum(401~402 & 405~406 MHz) for MICS March 19, 2009, By report and order(FCC09-23) • FCC, Medical implant communications, January 2003, http://wireless.fcc.gov/services/ index.htm?job=service_home&id=medical_implant • ArthurW. ASTRIN, Huan-Bang LI, and Ryuji KOHNO, “Standardization for Body Area Networks,” IEICE TRANS. COMMUN., Vol.E92-B, No. 2, pp. 366-372, February 2009 • Richard A.Comroe and D.J.Costello.Jr. , “ARQ Schemes for Data Transmission in Mobile Radio Systems,”,IEEE journal on selective areas in communications, vol. sac-2, No.4, July 1984