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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Slot Allocation for Periodic Traffic in Medical BANs] Date Submitted: [May, 2008]

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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

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  1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Slot Allocation for Periodic Traffic in Medical BANs] Date Submitted: [May, 2008] Source: [Changle Li, Huan-Bang Li and Ryuji Kohno] Company [National Institute of Information and Communications Technology (NICT)] Address [3-4 Hikarino-oka, Yokosuka, 239-0847, Kanagawa, Japan] Voice:[+81-46-847-5096], FAX: [+81-46-847-5431], E-Mail:[clli@nict.go.jp] Abstract: [Dynamic slot allocation for periodic traffic in medical BANs.] Purpose: [To illustrate the coexistence of medical and non-medical applications, providing a reservation-based dynamic slot allocation method for periodic traffic in BANs.] 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. <C. Li, H.-B. Li and R. Kohno>, <NICT>

  2. Slot Allocation for Periodic Traffic in Medical Body Area Networks Changle Li, Huan-Bang Li, and Ryuji Kohno National Institute of Information and Communications Technology (NICT) <C. Li, H.-B. Li and R. Kohno>, <NICT>

  3. Outline • 1. Background • 1.1 Introduction • 1.2 Problem statement • 2. Dynamic Slot Allocation • 2.1 Targets • 2.2 Realization example • 2.3 Summary • 2.4 Discussions <C. Li, H.-B. Li and R. Kohno>, <NICT>

  4. 1. Background • 1.1 Introduction • In the context of sensor networks, BANs are distinguished by • Short range • Small scale • Number of the devices. • Star topology • Typically one-hop applications. Lack of movement. Especially applicable for centralized protocols rather than distributed ones. • Traffic model • Mainly periodic traffic Ref.: 1. 15-08-0037-01-0006-ieee-802-15-6-technical-requirements-document-v-4-0.doc 2. B. Zhen, H.-B. Li and R. Kohno, “IEEE body area networks for medical applications,” ISMICT’07. <C. Li, H.-B. Li and R. Kohno>, <NICT>

  5. Introduction (cont.) • MAC protocols • Contention-based • ALOHA • CSMA-CA • Schedule-based • TDMA • FDMA • CDMA Integrated superframe structure e.g., in IEEE 802.11, 802.15.4 <C. Li, H.-B. Li and R. Kohno>, <NICT>

  6. 1.2 Problem statement • IEEE 802.15.4 GTS (guaranteed time slot) scheme is effective for time critical data, but several problems may occur: • Waste of resources (dedicated allocation, empty slots). • Traffic starvation (limited number of GTS and FCFS strategy without priority support) • Expiration for very low-rate traffic <C. Li, H.-B. Li and R. Kohno>, <NICT>

  7. Problem statement (cont.) • Access must be guaranteed in worse case scenarios • Close to the network capacity limit (saturated load) • under heavy load (non-medical applications) • Emergency burst traffic generated by a life-critical message. • In case of being on an inactive/sleep period • Or if there are not enough resources <C. Li, H.-B. Li and R. Kohno>, <NICT>

  8. 2. Dynamic Slot Allocation • 2.1 Targets • To solve the aforementioned problems of the original GTS scheme. • Adaptive to the traffic (different data rate and asymmetric traffic). • Guarantee QoS (priority support, dropping rate, delay). • Energy efficient. Reservation-based dynamic slot allocation <C. Li, H.-B. Li and R. Kohno>, <NICT>

  9. 2.2 Example Fig. 1. Example of slot allocation for periodic data flows What about non-periodic traffic? <C. Li, H.-B. Li and R. Kohno>, <NICT>

  10. 2.3 Characteristics of considerations • Avoid contentions (other than the access slots). • Reservation-based. Priority support. Adaptive to the traffic. • Energy efficiency • The device is only active in the allocated time slots and related beacon slots. So, it can enter in inactive mode during the remaining time. • Decrease in energy waste due to: idle listening, overhearing, contention, overhead. • Simplicity • Modify 15.4 to satisfy the slot allocation QoS support if not saturated <C. Li, H.-B. Li and R. Kohno>, <NICT>

  11. 2.4 In discussion • For non-periodic traffic, two simple options: • Transmission in contention access period (CAP) • Dedicated allocation in contention-free period (CFP) like 15.4 • For data flow without traffic information • It can be treated as non-periodic traffic. • For the downlink data • The coordinator can integrate the uplink/downlink data in consecutive slots, and then to inform the devices by a beacon. <C. Li, H.-B. Li and R. Kohno>, <NICT>

  12. Thanks for your attention! <C. Li, H.-B. Li and R. Kohno>, <NICT>

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