1. Signaling Acceptable Error Rate in TSPEC
November 2003
doc.: IEEE /973r0
November 2003
Signaling Acceptable Error Rate in TSPEC
Amjad Soomro, Kiran Challapali, Javier Del Prado, Zhun Zhong
Philips
Soomro et. al., Philips
Soomro et. al., Philips

2. November 2003
Comment Addressed
931
Soomro et. al., Philips

3. Current Traffic Specification (TSPEC)
November 2003
doc.: IEEE /973r0
November 2003
Current Traffic Specification (TSPEC)
These parameters are passed from Higher Layers to MAC
Except “Minimum PHY Rate” and “Surplus Bandwidth Allowance” which may be calculated by MAC
Mandatory Parameters (shall be specified by non-AP QSTA during TSPEC negotiation)
Nominal MSDU Size
Max Service Interval or Delay Bound
Mean Data Rate
Soomro et. al., Philips
Soomro et. al., Philips

4. Issues with current TSPEC
November 2003
doc.: IEEE /973r0
November 2003
Issues with current TSPEC
Packet errors exist on the wireless medium (and at the PHY SAP)
Some errors mitigated via retries (accounted for in surplus bandwidth allowance)
However, residual error remain at MAC SAP
Due to bursty errors on WLAN
Especially severe for low delay applications
Given that residual errors exist, how does the AP decide when to delete a TSPEC?
Soomro et. al., Philips
Soomro et. al., Philips

5. Example error tolerance for different applications
November 2003
Example error tolerance for different applications
Some applications are tolerant of errors
Example:
Video in general, scalable video in particular, can tolerate high error rates
Audio (VoWLAN) can tolerate some errors
However, medical applications have very low error tolerance
(HDTV can tolerate 2 packets/second
Document is: a/64)
Soomro et. al., Philips

6. Delay versus loss tolerance
November 2003
Delay versus loss tolerance IT
Audio/Video
VoIP
Delay
Residual error
Patient Monitoring
Soomro et. al., Philips

7. November 2003
The proposal
Applications can optionally specify the amount of errors they can tolerate
We propose to include in TSPEC the field Maximum Tolerable Error Rate
Definition: Unless the residual error rate for a flow exceeds Maximum Tolerable Error Rate the AP should not delete the TSPEC
QoS for 3G has a similar field
Soomro et. al., Philips

8. Advantages of the Proposal
November 2003
Advantages of the Proposal
QAP/QSTA knows when not to delete a TSPEC
For the QAP/QSTA to know if the QoS is met.
How to make delay versus loss tradeoffs…
In addition it could help figuring out max_retry_limit?
Soomro et. al., Philips