1. Ack Bitmap length for Burst ACK
July 2001
doc.: IEEE /434r1
January 2002
Ack Bitmap length for Burst ACK
Yasuo HARADA,
Isaac Lim Wei Lih, Tan Pek Yew
(Matsushita Electric Ind.)
Isaac, Matsushita Electric Ind.
Wei Lih Lim, Matsushita Electric Ind.

2. HD TV Transmission Requirement
July 2001
doc.: IEEE /434r1
January 2002
HD TV Transmission Requirement
Streaming rate: 24Mbps
36Mbps OFDM – a with 16QAM
Burst ACK to achieve higher throughput
MPDU size = 1402 bytes
Fragmentation is not needed
Bitmap ACK need to contain enough acknowledgement history to avoid excessive delay caused by lost of Burst ACK frame
Burst ACK is a factor feature to support HD TV transmission using a 16QAM modulation
Most of the MSDU size for AV steaming is less than 2403 bytes, so fragmentation is not necessary.
In order to avoid excessive delay due to lost of burst ack, bitmap need to carry a certain amount of acknowledgement history
Isaac, Matsushita Electric Ind.
Wei Lih Lim, Matsushita Electric Ind.

3. Practical example for ACK Bit map requirement
January 2002
Practical example for ACK Bit map requirement
Q.CF-Poll
Data#01
Data#02
Data#03
Data#04
Data#05
Data#06
Data#07
Data#08
ACK Req.
Burst ACK
Data
Long MPDU (No fragmentation)
1 MSDU = 1 MPDU　(ｅｘ．1402　byte)
8 MSDUs per burst
Burst ACK
ACK-Bitmap :
|01|02|03|04|05|06|07|08||09|10|11|12|13|14|15|16|
Draft 2.0
Conventional
ACK for 16 MSDUs history length
Burst ACK
ACK-Bitmap :
|01|02|03|04|05|06|07|08||09|10|11|12|13|14|15|16|
|17|18|19|20|21|22|23|24||25|26|27|28|29|30|31|32|
|33|34|35|36|37|38|39|40||41|42|43|44|44|46|47|48|
|49|50|51|52|53|54|55|56||57|58|59|60|61|62|63|64|
Required for
HD TV
ACK for 64 MSDUs history length
Isaac, Matsushita Electric Ind.

4. Simulation for Burst ACK
July 2001
doc.: IEEE /434r1
January 2002
Simulation for Burst ACK
Objective
Throughput and Delay v.s. Bitmap Ack Size
Scenario for simulation
Data Generation Rate: 24,000,000 bps
PHY: 36Mbps
MSDU Size: 1402 Bytes
Direct Transmission from source to destination (no relaying)
Dummy scheduler – AP polls sender and receiver in sequence
Data
Burst ACK
Burst ACK Req
QoS CF-Poll
Throughput is mac layer throughput
Delay is end-to-end the layer which generate and receive MPDU data payload.
Isaac, Matsushita Electric Ind.
Wei Lih Lim, Matsushita Electric Ind.

5. January 2002
Throughput
Bitmap ack size of 32 or more is needed to solve throughput variation due to lost/error on Burst Ack frame
Isaac, Matsushita Electric Ind.

6. January 2002
End-to-End Delay
Bitmap ack size of 32 or more is needed to solve delay jitter due to lost/error on Burst Ack frame
Isaac, Matsushita Electric Ind.

7. January 2002
Conclusion
As shown by the simulation results, acknowledging more than 16 MPDUs in a Burst Ack frame is needed to due with erroneous condition
Use addition flag to allow full use of the 32 bytes bitmap ack for unfragmented MPDU
for cases where data payload is smaller maxMSDU size.
Isaac, Matsushita Electric Ind.

8. Recommend text change for section 7.2.1.8
January 2002
Recommend text change for section
The frame format of the Burst Acknowledgement (BurstAck) frame is defined in Figure 21.4.
Octets: 2 2 6 32 4
Frame Control
Duration RA TA
BA Control
Sequence Control
Ack Bitmap
FCS
Bits: 0 to 3
4 – 13 15
TID
Reserved
Wait 14
Fragment
Figure 21.4 – BurstAck Frame Format
Use a reserve bit in BA Control field to indicate if fragments are included in Ack Bitmap for acknowledgement.
Isaac, Matsushita Electric Ind.

9. Section 7.2.1.8 Burst Acknowledgement
January 2002
Section Burst Acknowledgement
The following are recommended insertion to the text in section :
The Duration, RA and TA fields follows the rules defined in section for the ACK frame.
The BA control field consists of the TC, Fragment and Wait sub-fields. The TC contains the traffic class being acknowledged. The Fragment field, if set to 1, means that the Ack Bitmap contains fragments acknowledgement and can acknowledge up to 16 MSDUs. Bit position n of Ack Bitmap, if set to a 1 acknowledges MPDU with MPDU sequence number equal to (Sequence Control + n). Otherwise, each bit in the Ack Bitmap represent an acknowledgement for a sequence number, which can acknowledge up to 256 MSDUs. Bit position n, if set to a 1 acknowledges MPDU with MPDU sequence number equal to (Sequence Control + n * 16).
The Wait field, if set to 1, means that the acknowledgement results are not available. The contents of the Sequence Control and Ack Bitmap are reserved in this case. Otherwise, the Sequence Control field contains the fragment number and sequence number for traffic class TC corresponding to bit 0 of the Ack Bitmap.
Note: Remove existing line 10 – 13.
Isaac, Matsushita Electric Ind.