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January 2008
Jarkko Kneckt, Nokia
Slide 1
doc.: IEEE 802.11-08/0103r0
Submission
Peer Service PeriodDate: 2008-1-14
Name Affiliations Address Phone email Jarkko Kneckt Nokia Itämerenkatu 11-13,
00180 Helsinki, Finland
Janne Marin Nokia Itämerenkatu 11-13, 00180 Helsinki, Finland
Mika Kasslin Nokia Itämerenkatu 11-13, 00180 Helsinki, Finland
Authors:
January 2008
Jarkko Kneckt, Nokia
Slide 2
doc.: IEEE 802.11-08/0103r0
Submission
Abstract
This presentation provides description of peer service period. Peer Service Periods are used in frame exchange with MPs in light or deep sleep power management mode.
Contents– Peer service period overview
– Phases of peer service period• Initiation of peer service period
• Data transmission in peer service period
• Termination of peer service period
– Enhancements to the peer service period
January 2008
Jarkko Kneckt, Nokia
Slide 3
doc.: IEEE 802.11-08/0103r0
Submission
Phases in Peer Service Periods
• The Peer Service Periods may be divided into three phases1. Initiation
– MP transmits a trigger frame to initiate a service period.
– Power management mode specific times for triggering are introduced in 11-08/102
2. Data Transmission – Data transmission by using EDCA.
3. Termination– Last transmitted frame in contains set EOSP bit which is used to
indicate the termination of the peer service period
January 2008
Jarkko Kneckt, Nokia
Slide 4
doc.: IEEE 802.11-08/0103r0
Submission
Initiation of peer service period
• Null and PS-poll frames initiate a peer service period where a receiver MP may send data and management frames
• Data and management frames initiate two peer service periods where both MPs may send data and management frames– Both the triggering MP and the MP receiving trigger frame have own
independent peer service period
– Both peer service periods are also terminated independently
• Any PS-Poll, null, management or data frame that is received and acknowledged is considered as trigger frame if no peer service period is ongoing between the peer MPs.
• The peer service periods are independent from each other
• One MP may have multiple peer service periods ongoing at a time
January 2008
Jarkko Kneckt, Nokia
Slide 5
doc.: IEEE 802.11-08/0103r0
Submission
Data transmission in peer service period
• The MPs are awake for the duration of the peer service period
• May contain one or more TXOPs – 802.11n or other enhancements may be used for the TXOP
• Does not limit access categories of transmitted frames
• Does not limit the amount of transmitted frames
• Is directional and link specific– One peer service period exists at a time from MP to another
– One MP transmits frames and another receives frames.
January 2008
Jarkko Kneckt, Nokia
Slide 6
doc.: IEEE 802.11-08/0103r0
Submission
Termination of peer service period
• The peer service period is terminated when a frame where EOSP is set is transmitted and acknowledgement is received
• If acknowledgement is not received to the frame that contained EOSP, the frame shall be retransmitted at least once
January 2008
Jarkko Kneckt, Nokia
Slide 7
doc.: IEEE 802.11-08/0103r0
Submission
MAC frame header bits used in peer service periods
• More Data (MD) bit in unicast data frames– Indicates the status of the buffered unicast frames for the receiver
• MD bit in multicast and broadcast frames and bit 0 in Mesh TIM element– Indicates if more multicast or broadcast will be transmitted by the MP
• End of Service Period (EOSP) Bit in unicast frames– Indicates termination of the service period
• The separation of MD bit and EOSP enables the separate transmission buffer status information passing and control for service periods
• 802.11e and U-APSD uses both MD and EOSP bits
January 2008
Jarkko Kneckt, Nokia
Slide 8
doc.: IEEE 802.11-08/0103r0
Submission
Enhancements to the peer service period
• MPs may create instead of two peer service periods one bi-directional peer service period
• MPs define used service period type during the peer link creation– If both MPs set ‘Bi-directional Peer Service Periods’ –bit in ‘Mesh
Capability’ –field in ‘Peer Link Open’ and ‘Confirm’ –frames bi-directional peer service periods are used
– Otherwise “normal” peer service periods are only used for the link
• Bi-direction peer service period is initiated by trigger frame by intended receiver of data transmission– Unicasted and acknowledged PS-POLL, QoS-Null, data and
management frame may be used as a trigger frame
January 2008
Jarkko Kneckt, Nokia
Slide 9
doc.: IEEE 802.11-08/0103r0
Submission
Bi-directional peer service period
• All trigger frames frames initiate a bi-directional peer service period where both MP may send data and management frames
• The bi-directional peer service period is terminated when both MPs have indicated that they have transmitted all frames, EOSP is set and have received acknowledgement to the indication– EOSP-bit and More Data-bit are used to indicate end of service
period
January 2008
Jarkko Kneckt, Nokia
Slide 10
doc.: IEEE 802.11-08/0103r0
Submission
Bi-directional peer service period
• Bi-directional peer service periods– Better efficiency and controllability of the mesh service period,
because both sides may actively transmit data and other MP is not forced to receive only at any point
– Better coordination to transition from active mode to power save, no lost frames in power mode transition
January 2008
Jarkko Kneckt, Nokia
Slide 11
doc.: IEEE 802.11-08/0103r0
Submission
Strawpoll
• What is the most favorable peer service period type(s) in 802.11s:– Peer Service Period
– Bi-direcitional Peer Service period
– Both
– Don’t know / don’t care
January 2008
Jarkko Kneckt, Nokia
Slide 12
doc.: IEEE 802.11-08/0103r0
Submission
Appendix
Summary of the peer service period triggering in different power management modes
January 2008
Jarkko Kneckt, Nokia
Slide 13
doc.: IEEE 802.11-08/0103r0
Submission
Frame transmission in ‘Light sleep’ mode
• ‘Light sleep’ mode MP to ‘active’ mode MP frame transmission– ‘Light sleep’ MP may transmit (buffered) frames any time
– ‘Light sleep’ MP may enter to doze state when all frames are transmitted
• ‘Light sleep’ mode MP to ‘light sleep’ mode MP frame transmission– Beaconing ‘light sleep’ MP uses TIM field in its own beacon to indicate
presence of buffered frames to peer MPs
– Peer MPs checks if the peer MP indicates presence of buffered frames for it and if the bit is set, the MP triggers a peer service period
– Beaconing MP transmits buffered frames during peer service period
– Beaconing MP may enter to doze state when all the peer service periods have been ended
January 2008
Jarkko Kneckt, Nokia
Slide 14
doc.: IEEE 802.11-08/0103r0
Submission
Frame transmission in ‘Light sleep’ mode
• ‘Light sleep’ mode MP to ‘deep sleep’ mode MP frame transmission– ‘Light sleep’ MP triggers peer service period with ‘deep sleep’ MP
during its Awake Window
– ‘Light sleep’ MP transmits buffered frames during peer service period
– ‘Light sleep’ MP may enter to doze state when all the peer service periods have been ended (as well as ‘deep sleep’ MP)
January 2008
Jarkko Kneckt, Nokia
Slide 15
doc.: IEEE 802.11-08/0103r0
Submission
Frame transmission in ‘Deep sleep’ mode
• ‘Deep sleep’ mode MP to ‘active’ mode MP frame transmission– ‘Deep sleep’ MP may transmit (buffered) frames any time
– ‘Deep sleep’ MP may enter to doze state when all the frames is transmitted
• ‘Deep sleep’ mode MP to ‘light sleep’ mode MP communication– Beaconing ‘deep sleep’ MP uses TIM field in its own DTIM beacon to
indicate presence of buffered frames to peer MPs
– Peer MPs checks if the peer MP indicates presence of buffered frames for it and if the bit is set, the MP triggers a peer service period
– Beaconing MP transmits frames data during peer service period
– Beaconing MP may enter to doze state when all the peer service periods have been ended
January 2008
Jarkko Kneckt, Nokia
Slide 16
doc.: IEEE 802.11-08/0103r0
Submission
Frame transmission in ‘Deep sleep’ mode
• ‘Deep sleep’ mode MP to ‘deep sleep’ mode MP frame transmission– ‘Deep sleep’ MP triggers peer service period with beaconing ‘deep
sleep’ MP during its Awake Window
– ‘Deep sleep’ MP transmits buffered frames during peer service period
– ‘Deep sleep’ MP may enter to doze state when all the peer service periods have been ended (as well as beaconing ‘deep sleep’ MP)
– Note: ‘Deep sleep’ MP have to be in practice awake state some time in order to receive peer ‘deep sleep’ MP DTIM beacon and react to Awake Window)
