Priority QoS Facility in the MAC Layer for WBAN

1. Youjin Kim et al., ETRI Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Priority QoS Facility in the MAC layer for WBAN] Date Submitted: [15 July, 2008] Source: [Youjin Kim, Youngwoo Choi, Hyoungsoo Lee, Jaeyoung Kim] Company [ETRI] , [Yongho Seok] Company [LG Electronics] Contact: [161, Gajeong-Dong, Yuseong-Gu, Daejeon, South Korea] Voice: [+82-42-860-1224], FAX: [+82-42-860-5218], E-Mail:[youjin@etri.re.kr] Re: [IEEE 802. 15-08-0446-00-0006 ] Abstract: [This document presents the priority QoS facility in the MAC layer for WBAN] Purpose: [To stimulate discussion on the QoS MAC requirements and functions for BAN] 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 maybe made publicly available by P802.15.

2. Priority QoS Facility in the MAC layer for WBAN 15July, 2008 Youjin Kim*, Youngwoo Choi*, Hyungsoo Lee*, Jaeyoung Kim* Electronics and Telecommunications Research Institute* (ETRI) Yongho Seok** LG Electronics** Youjin Kim et al., ETRI

3. July 2008 Motivation and problem • WBAN hasheterogeneous traffics and different requirements • Individual link bit rate: 1kbps and 10kbps at low-end and 10Mbps at high-end (from BAN Technical Requirements) • High-end Application (e.g. Non-medical,Video streaming for SDTV with 4~5Mbps offered load) : Latency <200ms, PLR <10-7 • Low-end Application (e.g. Medical,Vital signs, ECG) : Latency <100ms, BER <10-10 • WBAN QoS metrics and policies could be different between high and low end applications • Among various QoS policies, what is the common QoS function, which is in MAC-level, to be applicable for both the video streaming and the delivery of vital signs? Slide 3 Youjin Kim et al., ETRI

4. July 2008 QoS Metrics for Vital signs? • Metrics for the vital traffics can be defined as the reliability and the latency ☞ How to increase the reliability with possible MAC-level techniques? Slide 4 Youjin Kim et al., ETRI

5. July 2008 Possible MAC-level techniques to increase the reliability • FEC • To ensure no data loss • But, FEC causes unnecessary protocol overhead in a reasonable error free environment • MAC is designed in a way that makes FEC optional • Retransmission • Failure to receive ACK, initiates retransmission • Retransmissions provide reliability • Priority • User specified messages (e.g. Emergency, Alarm) can have higher priority than others • Channel reservation • Reservation, or guaranteed time slot, is effective for time critical data Slide 5 Youjin Kim et al., ETRI

6. July 2008 QoS Metrics for Video streaming? • Metrics for video streaming could be combined as follows; • Rendered Video Quality Metrics (e.g. Mean Opinion Score) • Network performance Metrics (e.g. Packet Loss, Delay) • Link Metrics (e.g. PER, throughput) • Unique problem of video • Compressed video • Inter-frame dependency, Highly VBR, Prioritized Frame • Sensitivity to loss and delay • MOS is affected by packet loss with content dependency • Error resiliency and concealment • Tutorial [2] highlights the challenges for “Video over wireless” Slide 6 Youjin Kim et al., ETRI

7. July 2008 QoS Metrics for Video streaming (Cont’d) • Metrics for the video traffic can be combined among link, network performance and the rendered audio/video how shows to users well ☞ How to increase the MOS with possible MAC-level techniques? Slide 7 Youjin Kim et al., ETRI

8. July 2008 Possible MAC-level techniques for wellshowing to users • Selective Repetition to mitigate packet loss • Duplicated frame is sent multiple times in case of packet loss • Smart packet drop • If the decoder resolution of destination is known, the source can drop the lower priority data • Content aware transmission, etc., • Real-time video has different QoS requirements compared to stored media • Some video frames are more important than others (I>P>B frames)  Tutorial[2] shows the video transmission over WLAN Slide 8 Youjin Kim et al., ETRI

9. July 2008 Derived common QoS function from high and low end applications toward WBAN Possible, QoS facility in MAC layer For low end application For high end application • Selective Repetition • to mitigate packet loss • Smart Packet drop • Content-aware transmission, etc., • CRC • FEC • Retransmissions • Priority • Channel Reservation + • Low complexity • Low power ∩ ☞ The priority based QoS policy, which covers from the medical applications to the video streaming, is underlying among all QoS facilities ☞ To define the priority policy for WBAN, the traffic classes should be freshly discussed or simply obtained from the existing 802 standards? Slide 9 Youjin Kim et al., ETRI

10. July 2008 Mapping of user_priority to BAN access_priority ☞ Medical Traffic, which is similar to the traffic type of network control in 802.1D[3], can be segregated from Voice since medical traffic is likely to be less delay sensitive than Voice, but requires a higher delivery guarantee Slide 10 Youjin Kim et al., ETRI

11. July 2008 BAN Priority QoS Facility ☞ Access Category for medical traffics (AC_ME) is useful for transmitting vital signs, alarm messages, and command ☞ Excellent Effort (AC_EE) is more suitable than the best effort (AC_BE) in medical applications Slide 11 Youjin Kim et al., ETRI

12. July 2008 Conclusions • QoS Policy should be distinguished between low and high end applications • Low end(<100kbps) for primary medical and alarm messages: CRC, FEC, ACK, Retransmission, Priority, ..etc. • High end(<10Mbps) for mainly video transmission: Selective repetition, Smart Pack drop, content aware transmission, ..etc. • Most of all, the priority based QoS policy is underlying among all QoS facilities • 802.1D User Priority is useful for non-medical applications, however, the new traffic classifications and user priority for WBAN should be discussed like AC_ME Slide 12 Youjin Kim et al., ETRI

13. July 2008 References [1] 15-08-0037-03-0006-ieee-802-15-6-technical-requirements-document-v-4-0.doc [2] IEEE 802 Tutorial: Video over 802.11 (http://ieee802.org/802_tutorials/march07/) [3] IEEE Std 802.1D™- 2004, Media Access Control (MAC) Bridges [4] IEEE Std 802.11™-2007, Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications [5] ECMA-368, 2nd Edition / December 2007, High Rate Ultra Wideband PHY and MAC Standard [6] 15-08-0053-01-0006-the-mac-protocol-requirements-for-ban.ppt [7] 15-08-0305-00-0006-mac-consideration-for-non-medical-application-in-ban.ppt [8] 15-08-0332-01-0006-required-mac-protocol-features-for-non-medical-ban.ppt [9] 15-08-0334-02-0006-a-perspective-of-the-ban-mac.ppt [10] 15-07-0649-00-0ban-qos-ban.ppt [11] 15-07-0791-00-0ban-qos-mechanisms-in-ieee-802.ppt [12] 15-07-0851-00-0ban-consideration-mac-issues-ban.ppt Slide 13 Youjin Kim et al., ETRI

14. July 2008 Thank You ! Any Questions ? Youjin Kim et al., ETRI