November 20 01 doc IEEE 802 11 01601

November 20 01 doc. : IEEE 802. 11 -01/601 r 0 Delayed Acknowledgement v. s. Normal Acknowledgement Yasuo HARADA, Tan Pek Yew Matsushita Electric Ind. John Kowalski and Yoshihiro Ohtani Sharp Corp. Toshihiro Fujita Sony Corp. Submission 1 Harada Yasuo, Matsushita Electric Ind.

November 20 01 doc. : IEEE 802. 11 -01/601 r 0 Introduction • Sharp, Panasonic and Sony Requires High Bandwidth AV Transmission over IEEE 802. 11 e – AV data of up to 24 Mbps – Reasonably reliable AV Data transmission at MAC • Current Draft offers 4 types of Acknowledgement policies: – Delay ACK offers low overheads with reasonable reliability • We find option of Delay ACK meets our requirement for AV Data transmission Submission 2 Harada Yasuo, Matsushita Electric Ind.

November 20 01 doc. : IEEE 802. 11 -01/601 r 0 Content This presentations demonstrates • The simple buffering mechanism needed for Delay ACK – It frees complex buffering mechanism at layer above MAC for High Data traffic (such as 24 Mbps AV Stream) • Simulation results of Delay ACK vs. Normal ACK • Two Scenarios are performed • 0% PER & • 10% PER Submission 3 Harada Yasuo, Matsushita Electric Ind.

November 20 01 doc. : IEEE 802. 11 -01/601 r 0 Additional Implementation needed for Delayed Acknowledgement • Additional implementation for sender: – Allocate fixed size of buffer to store transmitted packets that have not being acknowledged. – Update acknowledged buffer entries on upon reception of delayed ACK – Set retransmitted data packet to higher priority – Remove buffered data packet if it is not being acknowledged after delay bound – Stop pull for MSDU when buffer size is full Submission 4 Harada Yasuo, Matsushita Electric Ind.

November 20 01 doc. : IEEE 802. 11 -01/601 r 0 Additional Implementation needed for Delayed Acknowledgement (con’t) • Additional implementation for receiver: – Allocate fixed size of buffer to store out of sequence data frames – Transmit delayed acknowledgement after received certain numbers of data packets – Set delayed acknowledgement frame to higher priority – Keep acknowledgement history up to certain size – Deliver buffered packets that are in sequence at the head of the list to upper layer when buffer is full. • For example as shown in the following figure, the receiver buffer will be filled up after received packet ID 10. So, Packet ID 2 to 4 will be delivered to upper layer, even through Packet ID 1 is still not yet being received. Error handling for this case is upper layer decision. Submission 5 Harada Yasuo, Matsushita Electric Ind.

November 20 01 doc. : IEEE 802. 11 -01/601 r 0 A example of Delayed Acknowledgement Transmission Sequence TXOP Qo. S CF-Poll S P Qo. S Data S Delayed ACK P Qo. S Data Submission P Qo. S Data Sender Qo. S CF-Poll AP/HC 6 Harada Yasuo, Matsushita Electric Ind.

November 20 01 doc. : IEEE 802. 11 -01/601 r 0 TX & RX Buffering Mechanism Upper Layer Fill in N-8 Data Frames Upper Layer Fetch Data Frames with TC-Seq 54 and 55 To upper layers & De-allocate Memory for Seq 54 & 55 Buffer Size = N Buffer Frames Sender Receiver Buffer Cleared TC-Seq = 54 TC-Seq = 55 TC-Seq = 56 TC-Seq = 57 TC-Seq = 58 TC-Seq = 59 TC-Seq = 60 TC-Seq = 61 TC-Seq = 62 TC-Seq = 63 TC-Seq = 58 TC-Seq = 60 TC-Seq = 61 TC-Seq = 62 TC-Seq = 63 Delay ACK Message Payload Received after receiving 10 Data Frames Empty Un. ACK TX to upper Layer Submission 7 Data Not Received Harada Yasuo, Matsushita Electric Ind.

November 20 01 doc. : IEEE 802. 11 -01/601 r 0 One example of Delayed ACK Transmission Sequence TXOP Legend PIFS 1 2 3 4 5 6 7 8 9 1 0 3 7 1 1 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 st Delayed ACK 1 2 3 4 5 6 7 8 9 Receiver Buffer Submission After Received 1 st Delayed ACK 1 0 Before Received 2 nd Delayed ACK 3 7 Data Seq 1 and 2 are being 1 delivered to upper layer 4 5 6 8 9 0 Qo. S Data 3 Qo. S Data (Retransmission) Delayed ACK After Received 2 nd Delayed ACK 1 1 1 1 1 2 3 4 5 6 7 8 1 1 2 6 Data Seq 3 to 11 are being delivered to upper layer 8 1 Error in transmission 2 nd Delayed ACK Before Received 1 st Delayed ACK Qo. S CF-Poll D ACK 2 nd D ACK 1 st D ACK Receiver Poll Sender Buffer SIFS Poll AP/HC 1 1 1 3 4 5 7 8 Harada Yasuo, Matsushita Electric Ind.

November 20 01 doc. : IEEE 802. 11 -01/601 r 0 Simulation • Aim – Compare MSDU throughput of the following acknowledgement policy: • Normal Acknowledgement • Delayed Acknowledgement • Scenario – AP/HC poll a wireless station using Qo. S CF-Poll at the rate of 250 polls per sec • Sender: Wireless station (send at full rate) • Receiver: AP/HC (acknowledgement generator) • MSDU size = 1402 bytes, PHY Rate = 36 Mbps OFDM Submission 9 Harada Yasuo, Matsushita Electric Ind.

November 20 01 doc. : IEEE 802. 11 -01/601 r 0 Normal Acknowledgement Data ACK PER = 0% Submission PER = 10% 10 Harada Yasuo, Matsushita Electric Ind.

November 20 01 doc. : IEEE 802. 11 -01/601 r 0 Delay Acknowledgement Configuration: • Duplication History Length = 64 • a Delayed ACK is being generated after received 10 data frames • Retransmission Time: 0. 001 s, Receiver Buffer Size: 200 frames PER = 0% Submission Data Delayed ACK PER = 10% 11 Harada Yasuo, Matsushita Electric Ind.

November 2001 doc. : IEEE 802. 11 -01/601 r 0 Summary Delay-Ack Policy perform effective high data transmission for AV data transmission Submission 12 Yasuo Harada et. al. , Matsushita Electric Ind.