mobiquitous 2004kimaya sanzgiri leveraging mobility to improve quality of service in mobile networks...
TRANSCRIPT
MobiQuitous 2004 Kimaya Sanzgiri
Leveraging Mobility to Improve
Quality of Service in Mobile Networks
Kimaya Sanzgiri and Elizabeth Belding-Royer
Department of Computer Science
University of California, Santa Barbara
MobiQuitous 2004 Kimaya Sanzgiri
Introduction
• Current Trends• Popularity of multimedia applications• Popularity of mobile networking• Support for multimedia content on mobile
devices
• Need for support of multimedia applications in mobile networks• Resource availability and QoS
MobiQuitous 2004 Kimaya Sanzgiri
Introduction
• Providing QoS support in mobile networks is difficult• Shared medium access
• Resource availability influenced by neighbors
• Mobility and dynamic topology• Neighborhood may change continuously
MobiQuitous 2004 Kimaya Sanzgiri
Introduction
• Several previously proposed QoS solutions• Basic idea
• Get QoS requirements from application• Query network to see whether satisfactory path is
available at user’s current location• If yes, make path available to application• If no, application is denied route
• Approach similar to wired networks
MobiQuitous 2004 Kimaya Sanzgiri
Motivation
• Mobile networks have special characteristics• Flexible connectivity• Resource availability influenced by
neighbors• Mobility
• Can these be leveraged to improve quality of service?
MobiQuitous 2004 Kimaya Sanzgiri
Observation
• Cellular networks have poor connectivity in some areas
• Users wander around observing signal strength bars on display
• Change of location often improves connectivity
MobiQuitous 2004 Kimaya Sanzgiri
Example from Cellular Networks
User
Base Station
I can’t hear clearly… the
signal is poor!
Maybe I should change my location…
User
Can you hear me
now?
User
Can you hear me
now?User
Aha! The signal is
great here!
MobiQuitous 2004 Kimaya Sanzgiri
Extending the Idea
• Lets apply the same idea to multihop mobile networks…
MobiQuitous 2004 Kimaya Sanzgiri
Changing Location in a Multihop Mobile Network
I want to see a
movie…
Network says: You don’t have enough
bandwidth
Maybe I should
change my location…
Aha!
MobiQuitous 2004 Kimaya Sanzgiri
Extending the Idea Further
• Build intelligence into network
• Network automatically guides user to new location
• Let us revisit our example…
MobiQuitous 2004 Kimaya Sanzgiri
Network-Suggested Location Change
I want to see a
movie…
Network says: You can’t watch the movie in your current location, but you
can if you move to location (x,y)
Aha!
MobiQuitous 2004 Kimaya Sanzgiri
Proposed Idea
• Leverage user mobility to improve service
• Network suggests new location• Beneficial to user
• Improved quality of service
• Beneficial to network• Spatial re-distribution of users• Efficient medium usage
MobiQuitous 2004 Kimaya Sanzgiri
Application Scenarios
• Applicable to networks with low to moderate mobility• Students on a campus• Users at a conference• Geography researchers in the field
• Not necessarily applicable to all ad hoc networks• Cars on a freeway
MobiQuitous 2004 Kimaya Sanzgiri
Implementation
• QoS-Aware AODV used as base QoS routing protocol
• Extended to leverage mobility
• Note that:• Idea is independent of routing mechanism• Other QoS protocols can be similarly
extended
MobiQuitous 2004 Kimaya Sanzgiri
QoS-Aware AODV (Q-AODV)
• RREQ specifies resource requirements
• Intermediate nodes check whether sufficient resources are available• If yes, forward the RREQ• If no, drop the RREQ
• Only destination may reply
• RREP specifies resource availability
MobiQuitous 2004 Kimaya Sanzgiri
Q-AODV Example
R
TP
V
QS DRREQ
RREP
MobiQuitous 2004 Kimaya Sanzgiri
Mobility-Enhanced Q-AODV (MQ-AODV)
• Extends Q-AODV to leverage mobility• RREQ broadcast at high power by
source• RREQ directly reaches more nodes• All recipients become candidates to
directly offer route to source• If necessary, source can move towards
node that offers best route
MobiQuitous 2004 Kimaya Sanzgiri
AODV Operation in Example Network
C
X
WV
U
T
S
R
QP
Y
Z
Congested Region
RegularTransmission
Range
RREQRREP
MobiQuitous 2004 Kimaya Sanzgiri
Q-AODV Operation in Example Network
C
X
WV
U
T
S
R
QP
Y
Z
Congested Region
RegularTransmission
Range
MobiQuitous 2004 Kimaya Sanzgiri
MQ-AODV Operation in Example Network
C
X
WV
U
T
S
R
QP
Y
Z
Congested Region
IncreasedTransmission
Range
RREQRREP
MobiQuitous 2004 Kimaya Sanzgiri
MQ-AODV Details
• Assumptions• Geographical location known• Transmission power adjustable• No obstacles
• User defines movement zone • Movement zone and regular
transmission range together define potential neighbor set
MobiQuitous 2004 Kimaya Sanzgiri
MQ-AODV Details
• RREQ broadcast by source at increased power• Should reach farthest potential neighbor• Contains location information of source
• First hop (potential neighbor) saves location information
• Regular route discovery procedure followed thereafter (at regular power)
MobiQuitous 2004 Kimaya Sanzgiri
MQ-AODV Details
• Destination sends RREP• Each intermediate node checks whether
it is the last hop• The last hop
• Adds its own location information to RREP• Looks up saved location information of
source• Increases transmission power if necessary
MobiQuitous 2004 Kimaya Sanzgiri
MQ-AODV Details
• On receiving RREP, source checks location information of last hop
• If necessary, source moves closer to last hop
MobiQuitous 2004 Kimaya Sanzgiri
MQ-AODV Limitations
• Movement distance limited by maximum transmission power
• Obstacles not considered
• Possibility of multiple users moving to same location
MobiQuitous 2004 Kimaya Sanzgiri
Protocol Evaluation
• Simulation-based (NS-2)
• 50 nodes in 1000m x 1000m area
• Regular transmission range = 250m
• MQ-AODV movement zone radius = 150m
• Between 2 and 10 application sessions (64 kbps, 180 seconds each)
MobiQuitous 2004 Kimaya Sanzgiri
Application Model
• Client-server-based streaming media application
• Implemented by modifying CBR• Client initiates session by sending
request to server• Server streams data at specified rate• Retry interval between 10 and 20
seconds
MobiQuitous 2004 Kimaya Sanzgiri
Mobility Pattern
• Graded mobility• 20 nodes static • Remaining nodes move based on
random waypoint• 10 nodes between 0 and 5 m/s• 10 nodes between 5 and 10 m/s• 10 nodes between 10 and 20 m/s
• Client and server nodes static
MobiQuitous 2004 Kimaya Sanzgiri
Performance Metrics
• Packet delivery fraction
• Number of data packets received
• End-to-end delay
• Fraction of received packets with unacceptable end-to-end delay (> 400ms)
• Routing load
MobiQuitous 2004 Kimaya Sanzgiri
Packet Delivery Fraction
MobiQuitous 2004 Kimaya Sanzgiri
Received Data Packets
MobiQuitous 2004 Kimaya Sanzgiri
End-to-End Delay
MobiQuitous 2004 Kimaya Sanzgiri
Delayed Packets
MobiQuitous 2004 Kimaya Sanzgiri
Routing Load
MobiQuitous 2004 Kimaya Sanzgiri
Performance Results
• MQ-AODV gives better packet delivery fraction, throughput, end-to-end delay and routing load as compared to Q-AODV
• AODV performs poorly due to lack of admission control
MobiQuitous 2004 Kimaya Sanzgiri
Conclusion
• Leveraging mobility does improve quality of service
• Future work:• Address limitations of MQ-AODV• Extend other QoS routing protocols
MobiQuitous 2004 Kimaya Sanzgiri
Thank You!
Questions/Comments?