1. Piggybacked Inter-Service Time
doc.: IEEE /457
September 2003
Piggybacked Inter-Service Time
Menzo Wentink
GlobespanVirata
Menzo Wentink, GlobespanVirata

2. Inter-Service Time (IST) is the time to the next Service Period (SP)
September 2003
INTRODUCTION
Inter-Service Time (IST) is the time to the next Service Period (SP)
The AP shall not transmit frames to the station during that time
IST is piggybacked on End of Service Period (EOSP) frames
Stations may go to sleep during IST period
IST is a flexible way to provide for non-ps-polled power save
IST allows for dynamic power save optimization under changing circumstances
IST works for non-TSPEC traffic, like unicast Best Effort
Imagine a hotspot with many active receivers. IST allows for stations to be asleep while the AP serves other nodes. This is not the case with current power saving, based on PS-Poll.
IST could also be TSF based value
Menzo Wentink, GlobespanVirata

3. Inter-Service Time Traffic to other stations SP SP
September 2003
Inter-Service Time
EOSP frame
EOSP frame
Traffic to other stations SP SP
Inter-Service Time (IST)
Menzo Wentink, GlobespanVirata

4. Implementation in 802.11e IST September 2003
Menzo Wentink, GlobespanVirata