1. Overheads in Data Stream Over WLAN
July 2001
doc.: IEEE /434r1
July 2002
Overheads in Data Stream Over WLAN
Tan Pek Yew, Jun Hirano &
Takashi Aramaki
(Panasonic)
Tan Pek-Yew, Panasonic
Wei Lih Lim, Matsushita Electric Ind.

2. Content Definition of Data Stream in .11 WLAN
July 2002
Content
Definition of Data Stream in .11 WLAN
Burst Ack Transmission in TXOP in .11e
Header Information Bit Rates in TXOP
Numerical Results
Conclusions
Tan Pek-Yew, Panasonic

3. Traffic Stream - Definition
July 2002
Traffic Stream - Definition
Based on IEEE802.11e Draft 3.0
A traffic stream is a set of MSDUs to be delivered subject to the QoS parameter values provided to the MAC in a particular traffic specification (TSPEC)
Tan Pek-Yew, Panasonic

4. Burst Transmission in TXOP (not Fragmented)
July 2002
Burst Transmission in TXOP (not Fragmented)
TXOP = 3968 uS
Burst Data = 10 packets
Total Data TX Time = 3868usec
CF POLL(44uS)
Burst Data(368uS)
Burst Data
BurstAckReq(24uS)
Burst Data
Burst Data
BurstAck(44uS)
CF POLL
SIF(16uS)
SIF
SIF
SIF
SIF
SIF
SIF
Based on 54 Mbps PHY
Full Header with Payload (2312 bytes) = 368 usec
Data Packet Header size = 4 usec
% for Address Fields = 4*(10)/3868 = 1.03%
Tan Pek-Yew, Panasonic

5. Burst Transmission in TXOP (Fragmented)
July 2002
Burst Transmission in TXOP (Fragmented)
TXOP = 3712 uS
Burst Data = 5 packets
Total Data TX Time = 3612 uS
CF POLL(44uS)
Burst Data(704uS)
Burst Data
Burst Data
Burst Data
BurstAckReq(24uS)
BurstAck(44uS)
CF POLL
SIF(16uS)
SIF
SIF
SIF
SIF
SIF
SIF
Fragment to 9 MPDUs
Payload(1)
(256 bytes) H
Payload(9)
(264 bytes) H
SIF
Based on 54 Mbps PHY
Full Header with Payload ( bytes) = 64 usec
Header size overhead = 4 usec
% for Address Fields = 4*(5*9)/3612 = 4.98%
Tan Pek-Yew, Panasonic

6. Header Address Bit Rates
July 2002
Numerical Results
Assumptions
Same PHY overheads as data rates increases
Worst Case Scenarios Encountered – Fragmented Packets
PHY (Mpbs)
Header Address Bit Rates 54
2.69 Mbps
108
5.38 Mbps
216
10.76 Mbps
432
21.52 Mbps
Tan Pek-Yew, Panasonic

7. Conclusions To Achieve High Throughput
July 2002
Conclusions
To Achieve High Throughput
Reduction of irrelevant header information
Substantial data rates can be saved from header information
Proposed that High Throughput and Future version of WNG to look into
irrelevant information be removed for data packets from one traffic stream
Tan Pek-Yew, Panasonic