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

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

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  1. doc.: IEEE 802.15-< 15-08-0597-01-004e > Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [The embedded CAP for GTS transmission for IEEE 802.15.4e] Date Submitted: [7 July, 2008] Source: [Rui Zhang, Tae Rim Park, Myung J. Lee and Jong-suk Chae] Company [CUNY and ETRI] Address [140th St. and Convent Ave, New York, NY, USA] Voice:[+1-212-650-7219], FAX: [], E-Mail:[rzhang@ee.ccny.cuny.edu] Re: [IEEE P802.15.4e Call For proposal] Abstract: [This document proposes an enhancement to IEEE 802.15.4-2006 MAC Layer with modified superframe structure named embedded CAP] Purpose: [This document is a response to call for preliminary proposals. ] 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. <Rui Zhang>, <CUNY>

  2. doc.: IEEE 802.15-< 15-08-0597-01-004e > The embedded CAP for GTS transmission for IEEE 802.15.4e Rui Zhang*, Tae Rim Park*, Myung J Lee*, Jong-suk Chae **, * CUNY, ** ETRI <Rui Zhang>, <CUNY>

  3. doc.: IEEE 802.15-< 15-08-0597-01-004e > Time Guaranteed Services • Required Time Guaranteed Services for IEEE 802.15.4e • For industrial applications • Two approaches • Enhancing GTS structure in 15.4b • A New TDMA Architectures may be necessary for certain applications <Rui Zhang>, <CUNY>

  4. doc.: IEEE 802.15-< 15-08-0597-01-004e > Time Guaranteed Services • Can current GTS solution provide guaranteed and reliable service? • Strictly Time Slot Assignment: Positive • Avoid Random back-off: • Hidden/Exposed terminal: Positive • Well designed time slot assignment to avoid hidden/exposed terminal problem. • Lossy wireless link: • Packet loss due to lossy wireless link: still need enhancement <Rui Zhang>, <CUNY>

  5. doc.: IEEE 802.15-< 15-08-0597-01-004e > Current GTS structure • Issues for current GTS solution • In lossy wireless links, retransmission is inevitable • If the retransmission can not be accomplished in its assigned GTS slot. • Long retransmission delay for non-delay sensitive traffic • Packet dropped for delay sensitive case. <Rui Zhang>, <CUNY>

  6. doc.: IEEE 802.15-< 15-08-0597-01-004e > Proposed Ideas • In 15.4b, a CFP slot for one node’s transmission • Proposed idea: Embedded CAP • To allow remaining time in GTS for other nodes to (re)transmit frames via CSMA/CA <Rui Zhang>, <CUNY>

  7. doc.: IEEE 802.15-< 15-08-0597-01-004e > An Example Timeline Successful Longest frame transmission = 360 symbols Still 600 symbols = 9.6 ms is left Longest Frame + tACK + ACK + LIFS = 360 symbols 802.15.4 PHY rate: 250kb/s = 62.5k symbols/s (QPSK) 266 32 22 40 One symbol = 16 us <Rui Zhang>, <CUNY>

  8. doc.: IEEE 802.15-< 15-08-0597-01-004e > Operation of Embedded CAP • No change for each node’s GTS slot. • During other GTSs • Nodes wait for ACK • CSMA/CA to compete the channel for (re)transmission • Some special cases • Multiple packets: ACK should notify the existence of subsequent frames until the final ACK • No packet: the assigned GTS device send a short probe frame and the ACK(broadcast type) will be sent back by PC to release the channel for other nodes <Rui Zhang>, <CUNY>

  9. Multiple packets case: burst data solution <Rui Zhang>, <CUNY>

  10. No packet case: free the channel for others to compete <Rui Zhang>, <CUNY>

  11. doc.: IEEE 802.15-< 15-08-0597-01-004e > An Example for Latency Improvement 10 11 12 9 • Star topology • Node 1-7 have periodical data to report to PC(PAN Coordinator) • Node 1-7 have been assigned GTS slots respectively. 4 8 PC 3 2 5 7 1 6 <Rui Zhang>, <CUNY>

  12. doc.: IEEE 802.15-< 15-08-0597-01-004e > • For15.4b case: the node 1 needs to wait a whole beacon interval to retransmit. Latency = 491ms <Rui Zhang>, <CUNY>

  13. doc.: IEEE 802.15-< 15-08-0597-01-004e > • Proposed Embedded CAP: the node 1 can access node 2’s CFP using CSMA/CA .Latency = 15.36ms <Rui Zhang>, <CUNY>

  14. doc.: IEEE 802.15-< 15-08-0597-01-004e > Summary for Embedded CAP • Enlarged Effective GTS slots • A node can use others’ GTS slots to retransmit its GTS frame • Potential latency reduction of GTS frame • Enlarged Effective CAP Period • Residual time for each GTS slot is available for other nodes via CSMA/CA • Enhanced packet delivery • More “reliable and guaranteed” than current solution • Little modification <Rui Zhang>, <CUNY>