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: MAC Enhancement and Cross-layer Information Date Submitted: 13 Nov, 2007 Source: Seong-Soon Joo, YoungHwan Ham, Sang Joon Park, Cheol Sig Pyo Company: ETRI Address: 161 Gajeong-dong, Yuseong-gu, Daejeon, KOREA Voice: +82-42-860-6333, FAX: +82-42-860-4197, E-Mail: ssjoo@etri.re.kr Re: Abstract: To clarify the scope of IEEE802.15.4e, user requirements are extracted from the PAR for P802.15.4e (15-07-0859-01), and constraints and criteria for alternative solutions are considered. As for MAC enhancements, the use of cross-layer information is suggested and an issue on the scope is raised. Purpose: To raise an issue on the scope of IEEE802.15.4e 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. ETRI

2. MAC Enhancements and Cross-layer Information Seong-Soon Joo*, YoungHwan Ham, Sang Joon Park, Cheol Sig Pyo ETRI ETRI

3. Task of the P802.15.4e • Problem to be solved in P802.15.4e • What is the problem to be solved in 802.15.4e ? • Formulate problem: current state  desired state, requirements • Analyze problem: constraints, criteria to be used in evaluating solutions • Search alternative solutions, Select the preferred solution, Specify • Found in 802.15.4e PAR • What are requirements, constraints, criteria for the problem? • Purpose: User requirements • determinism, mixed service, reliability, power efficiency, fast recovery, low latency, direct RFD communication • Scope: Preferred solutions • TDMA, channel hopping, improved CSMA, flexible GTS, asymmetrical keys, (latency ?) • Enough detailed requirements? Where are the constraints and criteria? ETRI

4. SG4e Purpose Study group investigating 802.15.4-2006 MAC enhancements such as: • Support for Determinism • e.g. TDMA supporting from a few to 10,000s slots • Mixed service and power savings levels in one network (dynamic transmit power control) • Frequency diversity for retransmissions for improved reliability • Low duty cycle operation with beacons for power efficiency • Distributed management of time slots and frequency hopping patterns for fast recovery from regional failures • 2ms per hop latency including 1 retransmission • Direct communication between Reduced Functionality Devices in the network ETRI

5. Scope • The intention of this amendment is to enhance and add functionality to the 802.15.4-2006 MAC to a) better support the industrial markets and b) permit compatibility with modifications being proposed within the Chinese WPAN. • Specifically, the MAC enhancements to be considered will be limited to the following: • TDMA - to provide: • determinism, • enhanced utilization of bandwidth • Channel Hopping - to provide additional robustness in high interfering environments and enhance coexistence with other wireless networks • GTS - to increase its flexibility such as: • supporting peer to peer, • the length of the slot, and • number of slots • CSMA - to improve throughput and reduce energy consumption • Security - to add support for additional options such as asymmetrical keys • Low latency - to reduce end to end delivery time such as needed for control applications ETRI

6. Refine the Requirements • User requirements • Determinism: how much accurate in synchronization is needed ? • Mixed service: what levels of services are required ? • Reliability: how reliable in terms of the loss rate is guaranteed ? • Power efficiency: how much improved compare to 15.4-2006 ? • Fast recovery: how fast converged on self-organizing ? • Low latency: 2ms per hop including 1 retransmission • Direct RFD communication • Any other requirements ? • Specify the goals of P802.15.4e • Improve performance in accessing media and networking • latency, loss rate, fast recovery, power saving • Support multiple grades of services • latency jitter, loss rate, security level on data transmission • New features • direct RFD communication, … ETRI

7. Constraints, Criteria • Constraints • Maintain primitives on the service access points of 15.4-2006 • physical layer, service specific convergence sublayer, management layer • PD-SAP, MCDS-SAP, MLNE-SAP, PHY PIB, MAC PIB • Additional features, do not make conflicts with the 15.4-2006 • independent features • use of information provided through the SAPs of 15.4-2006 • require to modify the primitive on the SAP ?? • require to invent new primitives on the SAP ? • Criteria • Measures on achieved level to the requirements • latency, latency jitter, loss rate, power, convergence time, power saving, reliability, … • Complexity of the solution • cost, … ETRI

8. Possible Alternative Solutions • Considering the criteria with the specified requirements • latency, latency jitter, loss rate, power saving, fast recovery, … • TDMA, channel hopping, improved CSMA, flexible GTS • require to modify primitives or to invent primitives ? • Use of the cross-layer information • Information from network layer • topology information • Nonbeacon-enabled mode is more flexible, but cannot support wakeup & sleep • If scheduled without beacon by using topology information, energy saved low latency can be achieved • Information from physical layer • signal detection • If detects the event, asynchronized MAC can be introduced • power consumption when only need time, low latency, reliable support with channel hopping ETRI

9. Conclusions • Formulate the problem more rigorously before going further • Requirements • Constraints • Criteria • Check the limitation on MAC enhancement, while maintaining compatibility • PD-SAP, MCDS-SAP, MLNE-SAP, PHY PIB, MAC PIB • Use of the cross-layer information • Extend views on alternative solutions • Channel hopping • TDMA, topology aware TDMA scheduling • Improved CSMA, asynchronous MAC with signal detection • Flexible GTS, asymmetric key ETRI