Transcript Pan20051222,Utilization of the IEEE802.11 Power Save Mode with

Utilization of the IEEE802.11
Power Save Mode with IP
Paging
Marco Liebsch, Xavier P' erez-Costa
NEC Europe Ltd., Network Laboratories,
Kurfuersten-Anlage 36, 69115 Heidelberg,
Germany
{liebsch, perez-costa }@netlab.nec.de
ICC 2005
Outline








Introduction
Paging architecture
Protocol operation
Address and Identification Scheme
Standard IEEE802.11 Power Save Mode –
unicast V.S. multicast
Performance Evaluation
Analytical Evaluation
Conclusion
Introduction – Mobile IPv6
Home Network
Mov.1
Mobile Node
Mobile Node
Home Address
Care-of Address
Mov.2
Home Agent
Trans.1
C
N
c
Correspondent Node
Trans.2
Router
Trans.3
Trans.4
Binding –
The mapping of Home Address
and Care-of Address
Introduction – IP Paging Service

Phenomenon



Only a fraction of powered mobile terminals
participate in a data session at a time
Wireless bandwidth and the mobile devices'
battery energy waste
How to…


Save the battery power
Decrease signaling load both on network and
the air
Introduction – MN with Paging

Idle & Active Modes
Receive Paging Request or
Open Connection
Update
location
when PA
change
Idle
Active
Update
location on
every
handoff
All Connection Closed
or Active timeout
The operator often arranges several access router as a Paging Area,
which is identified by a PA address as well as always a multicast address.
Introduction – IP Paging Service

Dormant state
Switch network interface card (NIC) into
power save mode (PSM)
 Reduce transmit (Tx) and receive (Rx)
activity to save energy resources
Dormant Mode Host Alerting
RFC 3132 - Dormant Mode Host Alerting ("IP Paging")


Problem Statement
Seamoby, http://www.ietf.org/html.charters/seamoby-charter.html
Introduction – IP Paging Service

The MNs at idle mode could register after a
long period or crossing over the customized
geographic region, rather than for each handoff.



To reduce registration cost
The operator often arranges several access
router as a Paging Area, which is identified by
a PA address as well as always a multicast
address.
Home Address – CoA  Home Address – PA Address
Introduction – IP Paging Service

Paging


The network locates and wakes up a
dormant mobile
How to communicate with a mobile device
in Dormant state?
Introduction – Paging
HA
Registration
z
z z
zz
HA
Registration
Paging
z
Paging architecture

Basic functional entities for paging:




Dormant Monitoring Agent (DMA) : buffer IP data
packets addressed to mobile terminals in PSM.
Tracking Agent (TA) : tracks the mobiles' location
with the granularity of a paging area
Paging Agent (PA) : coordinates the paging
procedure within a registered paging area
Paging Controller : full control the paging
procedure and implements the TA and DMA
function
Paging architecture
Protocol operation

Active state


Paging Controller doesn' t maintain the
mobile terminal' s registration
Dormant state


Buffer those data packets addresed mobile
terminal
Trigger the paging procedure (register first)
Protocol operation - Registration , paging ,
de-registration
Associated registration information
+ paging area' s identifier
Change
state from
Active to
Dormant
With current
location
Set state to
active
With PID
Address and Identification
Scheme




Address of paged mobile device might obsolete
Paging identifier (PID)
unique identification of mobile terminal in Dormant
state
Derivate IPv6 Solicited Node Multicast address
Terminal NIC'
s MAC
address
Address and Identification
Scheme
Least 3 significant byte of
MAC address of each NIC
NIC type
(IEEE802.11 ,
Bluetooth , CDMA, ...)
Actual length if
this fraction
THE STANDARD IEEE802.11
POWER SAVE MODE

Power save


Doze state


NIC receive traffic at regular beacon interval (BI)
Authentication & Association


Switch mobile device' s state from RxTx state to Doze state
Perform after mobile device select a AP
Mobile device inform AP about Listen Interval
parameter

Listen Interval :the amount of beacon interval a NIC remain
unreachable before listening to the next beacon
THE STANDARD IEEE802.11
POWER SAVE MODE - unicast





Mobile device in the PSM :
AP assign the mobile device’s NIC an Association
Identifier (AID)
AP listen to the packets addressed to the mobile
device
Packet buffered in AP
Traffic indication bitmap (TIM) inform mobile device
about buffer packets


TIM sent with each beacon
Mobile device sent Power Save Poll (PSP) message
to poll buffered packets
THE STANDARD IEEE802.11
POWER SAVE MODE - multicast


Multicast packets buffered at AP and forward
mobile device at regular interval (BI)
How the mobile device know when to listen
multicast packets? And how to delivery?



Beacon comprise a Delivery Traffic Indication Map
(DTIM)
Synchronization : beacon advertise a DTIM
Counter
Moredata Flag
NIC' s MAC address
PERFORMANCE
EVALUATION



Total cost (Ctotal ) , paging delay cost
(Cdelay ) , energy cost (Cerergy)
Ctotal = Cdelay + Cenergy
Paging delay : link delay + queuing
delay + wireless delay
dd : downlink
paging delayy
du : uplink paging
delay
PERFORMANCE
EVALUATION





μw: IEEE802.11 specific wireless process rate
dl : link delay between AP and Paging Controller
dw : IEEE802.11 specific wireless delay (dw = 1/μw)
ρ. BI : DTIM period (multiple beacon interval)
Queuing delay (dqueue) : Affected by DTIM period , multicast
frame received before paging request , wireless delay

PERFORMANCE
EVALUATION
PERFORMANCE
EVALUATION


Downlink delay include delay caused by
the transmission of N previously
multicast frames.
PERFORMANCE
EVALUATION

Total paging delay dp = dd + du

Delay cost

β: cost per second delay
PERFORMANCE
EVALUATION - energy cost





Session duration (SD) : time between two session
start
Timeout value (T) : cause the mobile device enter
Dormant State and PSM after the end of session
Idle duration (ID) : listen to Paging Request packets
every DTIM period
Energy cost : during the inter-session interval , the
time a mobile device' s NIC in RxTx state or listen
and deliver multicast packets each DTIM perio d.
Energy cost
The time a NIC
Cenergy =
α ‧k
consumes energy
Unit of cost
per second
of activity
to receive or send
data
Analytical Evaluation
session
interval

To estimate the cost efficiency, we evaluate the
impact of the session interval (IS ) , multicast
traffic load (N ) , DTIM period (ρ ‧BI) to the total
cost
Analytical Evaluation

Fig. 8 illustrates the total costs for two
different DTIM period settings
Analytical Evaluation









Environment :
AD : 30 seconds
T : 5 seconds
Cost unit of paging delay β and relative
energy consumption α: 1
IS : between 35 seconds and 200 seconds
Previously buffered data packets at AP : 20
multicast packets
Link delay : 5 ms
Wireless delay : 10 ms
BI : 100 ms
Analytical Evaluation

Low multicast traffic , less paging delay cost.

multicast PSM queue does not introduce a major
delay
Analytical Evaluation


The active period small compare to DTIM period
Energy cost decrease with the increasing session
interval
Analytical Evaluation

Increase the multicast load on the PSM
queue (N)
Analytical Evaluation

However , if low load condition ? ?
Conclusion


It' s a sub-optimal solution, but it utilized
without modify the IEEE802.11 AP
It can support initial integration and
migration scenarios toward future
mobile communication system.
Favorite English sentence

An analytical evaluation of energy and
paging delay costs allows estimation of
the proposed mechanism’s efficiency,
which might be sub-optimal for high
load conditions , but appropriate to
support migration scenarios towards
future heterogeneous access mobile
communication networks.
Q &A