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: [Energy Efficient MAC protocol for Low Energy Critical Infrastructure Networks] Date Submitted: [18 Sep, 2011] Source: [Hao Liu, Guolian Yao, PingpingXu,] Company [Beelinker Technology Co., Ltd. Southeast University] Address [339 Linquan Road, Suzhou Industrial Park, Jiangsu 215123, China] [ 2 Si Pai ou,Nanjing,210096,China] Voice:[+86-13951080520，+86-25-83794525], E-Mail:[liuhao@beelinker.com, guoliang@ieee.org, xpp@seu.edu.cn ] Re: [Respond for CFP] Abstract: [An Energy Efficient MAC Proposals for Low Energy Critical Infrastructure Networks applications] Purpose: [Presented to the IEEE 802.15.4k LECIM task group for consideration] 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. Beelinker Technology Co.ltd

2. Introduction July 2011 • Combination of inputs • Ideas shared in May 2011 meeting • Idea discussion in July 2011 meeting • Test-bed based experiment results • Reference documents: • P802.15-11-0478-00 • P802.15-11-0348-00 • Draft IEEE P802.15.4e/D5.0, June 2011 Beelinker Technology Co.ltd

3. Overview • Introduction • Channel Access Description • Packet Structure Definition • Discussion Beelinker Technology Co.ltd

4. LECIM Application requirements • Low power consumption, end point need to periodically go to sleep to conserve energy • Large number of nodes, >1000endpoints, High channel access efficiency is required. • Unreliability of the channel conditions, Propagation path loss of at least 120 dB Beelinker Technology Co.ltd

5. IEEE P802.15.4e MAC-- Basic CSL Operation • Challenges in 802.15.4K applications： • Larger number of endpoints make high channel contention. Through 8 nodes test-bed based experiments, we observe that even 0.5 packet/s traffic with 50 bytes packet length (0.5kbps/s), large buffer accumulation takes place in nodes. • Imperfect channel condition led to packet lost during transmission, packets buffer schemesand retransmission is necessary. • It cost a long period for node to seize the channel again in duty-cycling operation, so the buffered packets need to be drained ASAP. Beelinker Technology Co.ltd

6. Our Schemes- BT-MAC Buffer design Consideration Current typical off-the-shelf nodes ( equipped with 802.15.4 radio part ) Traditional program cost 1,500 bytes ram footprint, which used for variable allocation and operation system running. 8,500 bytes spare ram is available for buffer design with MSP430 microcontroller has 10k bytes ram Telosb Maximal frame length of MPDU in IEEE 802.15.4 2006 standard is 128 bytes Total buffer capacity available in Telosb node: 8500/128=66, which is sufficient for buffer based MAC scheme design Beelinker Technology Co.ltd

7. Our Schemes- BT-MAC Batch transmission ( Based on IEEE P802.15.4e -- Basic CSL Operation ) • If a sender detect N packets in buffer, it launch batch transmission with high efficiency. • After receive the first ACK, sender transmit a bulk of packets, then wait a group ACK that acknowledge the series. • If packets lost caused by imperfect channel condition, sender retransmit the packets. Packet accumulated in buffer Batch packets number is embedded in the preamble …… Node A data1 data0 data0 data0 data2 data3 dataN wakeup ack ack listen Node C Group Ack to confirm the batch series. The packet which not received are reply to sender for retransmission Early ack to end preamble and invite the transmission. It also contains free buffer size information on the receiver Beelinker Technology Co.ltd

8. MAC Protocol Description Reliability Transmission Consideration • The first data packet has the information about how many packet need to send in current burst transmission. • The first ACK includes the information about spare buffer space on the receiver, which can be used for batch transmission control. • The second ACK is used for acknowledge which packets are received successfully, which is store in the bitmap field. Beelinker Technology Co.ltd

9. Our Schemes- BT-MAC Packet buffer scheme • Important packet parameters • Nmax-- the maximum packets allowed in a batch transmission • Ncur-- calculated packets number in a burst transmission • Nbst-- current actual packets number in a burst transmission • Qmax--maximum capacity of node • Tmax—maximum time allowed by fairness requirement. • Nbst1 < Qmax-η2 • Let • So • if Ncur >Nmax, Nbst=Nmax; • else if Ncur≤ Nmax, Nbst=Ncur; • K: Transmission speed, Lack: length of ACK packet, η2 : buffer length in the receiver Ldata: length of data packet, tsifs: interval of two consetive data packets Nbst1 Qmax η1 η2 sender receiver Beelinker Technology Co.ltd

10. Packet Structure modification Extend the Frame of 802.15.4 2006 to support burst transmission and reliability transmission Data0 packet Structure ACK0 packet Structure ACK1 packet Structure Beelinker Technology Co.ltd

11. Experiment results Experiments senarios Senario: 8 nodes are deployed in a living room, each node is placed on top of a cup. Node 6 is the receiver. Beelinker Technology Co.ltd

12. Thank you for your attention Any Questions ? Beelinker Technology Co.ltd