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Proposed Timestamp Field for Strictly Ordered Indication
Month 2000 doc.: IEEE /xxx July 2001 Proposed Timestamp Field for Strictly Ordered Indication Yoshihiro Ohtani Sharp Corporation 10 July 2001 Yoshihiro Ohtani, Sharp John Doe, His Company
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Abstract of this presentation
Month 2000 doc.: IEEE /xxx July 2001 Abstract of this presentation Problem Statement It becomes difficult for the receiver MAC layer to execute Strictly Ordered indication efficiently when QoS Data which has a delay bound and is transmitted with the delayed ACK option. Proposal A new timestamp field, which indicates the lifetime of the data frame should be indicated at the receiver station, is proposed to resolve the problem stated above. Yoshihiro Ohtani, Sharp John Doe, His Company
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Problem for Strictly Ordered indication
July 2001 Problem for Strictly Ordered indication Delay bound of Packet 9 Delay bound of Packet 7 Delay bound of Packet 6 Delay bound of Packet 5 Sender LLC 1 2 3 4 5 6 7 8 9 10 11 12 Sender MAC 1 2 3 4 5 3 4 5 6 7 4 6 7 8 9 6 7 8 9 10 TXOP Receiver MAC 1 2 Dly ACK 3 5 Dly ACK 4 Dly ACK 7 9 10 Receiver LLC ? ? ? ? ? ? ? ? ? ? ? ? ? 1 2 3 4 5 The receiver MAC Layer cannot judge until when it should wait for the arrival of Packet #6, nor, when it should discard #6 and indicate Packet #7. Yoshihiro Ohtani, Sharp
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Problem for Strictly Ordered indication
July 2001 Problem for Strictly Ordered indication Delay bound of Packet 12 Delay bound of Packet 9 Delay bound of Packet 7 Sender LLC 7 8 9 10 11 12 Sender MAC 3 4 5 6 7 4 6 7 8 9 6 7 8 9 10 11 12 13 14 15 16 17 Receiver MAC 3 5 Dly ACK 4 Dly ACK 7 9 10 Dly ACK 11 12 13 14 15 Dly ACK 16 18 Receiver LLC 3 4 5 7 9 10 Estimated Deadline for Packet 7 by the receiver If the receiver MAC Layer somehow estimate the delay bound for received packets, many received data may not be indicated within its real delay bound. Yoshihiro Ohtani, Sharp
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Proposed Timestamp option for QoS Data ( Conceptual explanation )
July 2001 Proposed Timestamp option for QoS Data ( Conceptual explanation ) Sender LLC Receiver LLC Sender MAC TSF Timer Receiver MAC TSF Timer LLC PDU 7:12 7:12 Timestamp 7:42 LLC PDU Timestamp field holds the deadline ( TSF timer value in unit of 16us ) until when the LLC packet should be indicated to the receiver LLC layer. DlyACK Delay bound ( 0:30 ) 7:42 LLC PDU DlyACK 7:42 LLC PDU Yoshihiro Ohtani, Sharp
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Strictly Ordered indication using Timestamp information
Month 2000 doc.: IEEE /xxx July 2001 Strictly Ordered indication using Timestamp information Delay bound of Packet 9 Delay bound of Packet 7 Delay bound of Packet 6 Delay bound of Packet 5 Sender LLC 1 2 3 4 5 6 7 8 9 10 11 12 Sender MAC 1 2 3 4 5 3 4 5 6 7 4 6 7 8 9 6 7 8 9 10 Receiver MAC 1 2 Dly ACK 3 5 Dly ACK 4 Dly ACK 7 9 10 Receiver LLC 1 2 3 4 5 7 9 The receiver MAC Layer can indicate Packet #7 within its delay bound, after waiting for the arrival of the Packet #6 until just before the deadline of Packet #7. Yoshihiro Ohtani, Sharp John Doe, His Company
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Proposed Option to the MAC Frame Format for QoS Data
Month 2000 doc.: IEEE /xxx July 2001 Proposed Option to the MAC Frame Format for QoS Data LLC PDU - Timestamp field can be set just for QoS Data - The ID for this option will be added to TC Info field WEP MAC Header 32 IV 4 Time Stamp 2 LLC PDU ICV 4 FCS 4 ( Without RS Option ) ( With RS Option ) 32 16 208 16 208 16 208 16 208 16 XX 16 FCS 4 Yoshihiro Ohtani, Sharp John Doe, His Company
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Proposed Changes to TS Info field
Month 2000 doc.: IEEE /xxx July 2001 Proposed Changes to TS Info field TS Info Field ( currently 1 byte ) 1 2 3 4 5 6 7 Traffic Type rsvd ACK Policy rsvd Delivery Priority TS Info Field ( 2 byte ) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Traffic Type Time Stamp ACK Policy FEC Delivery Priority rsvd Yoshihiro Ohtani, Sharp John Doe, His Company
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This is achieved by defining an optional timestamp field.
July 2001 Conclusions A mechanism to order frames in the original sequence when delayed ACK option is used, to achieve strict reordering of frames from end-to-end. This is achieved by defining an optional timestamp field. Yoshihiro Ohtani, Sharp
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