WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Department of Information EngineeringUniversity of Padova, ITALY
On Providing Soft-QoS in On Providing Soft-QoS in
Wireless Ad-Hoc NetworksWireless Ad-Hoc Networks
{andrea.zanella, daniele.miorandi, silvano.pupolin}@dei.unipd.it
Andrea Zanella, Daniele Miorandi, Silvano Pupolin, Paolo Raimondi
WPMC 2003, 21-22 October 2003
Special Interest Group on NEtworking & Telecommunications
WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Outline of the contents
Motivations & Purposes
Soft-QoS & Call Admission Control
Path creation & maintenance
Results
Conclusions
WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
What & Why…
Motivations &Purposes
WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Motivations
Ad-hoc networks are a valuable solution to
Extend in a multi-hop fashion the radio access to wired networks
Interconnect wireless nodes without any fixed network structure
In these contexts, providing QoS is a key issue
audio/video streaming
interactive games
multimedia
Classic QoS support methods involve
QoS-routing
Call-Admission-Control (CAC) mechanisms
MAC-layer Resource Reservation (MRR) strategies
WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Aim of the study
Providing basic Soft-QoSSoft-QoS support over low-profilelow-profile
ad-hoc wireless networks
No hard QoS guarantees Soft QoSSoft QoS
Simple QoS routing algorithm modified AODVmodified AODV
Simple CAC mechanism distributed statistical CACdistributed statistical CAC
No static MRR statistical MRRstatistical MRR
WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Introduction to QoS issues
Soft QoS & CACSoft QoS & CAC
WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Hard & Soft QoS
Widely used in wired
networks
Integrated Services: flow
based (RSVP)
Differentiated Services:
class based
Suitable for wireless
networks
Applications may work
even if, for short periods of
time, QoS requirements
are not satisfied
Deal with limited bandwidth
and radio channel
Hard-QoS Soft-QoS
WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
QoS parameters required per link
Minimum peak band: Br
End-to-End Delay: Dr
Soft QoS parameter: Target Satisfaction indexTarget Satisfaction index
r = percentage of pcks expected to satisfy QoS constrains
r = 1 hard QoS
r = 0 pure best-effort
Path Service Levels P = (p1,…, pN)
Path Peak Bandwidth
Path Delay
Soft-QoS parameters
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WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Call-Admission Control
Path is feasible if Bandwidth constrained requests
Delay constrained requests
Using Gaussian approx, Bandwidth and Delay statistic is
determined by mean and standard deviation
Bandwidth constrained requests
Delay constrained requests
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WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Statistical Resource Reservation
Bandwidth-constrained
Delay-constrained Extra-delay margin given to
each link along the path is inversely proportional to the mean link delay
Resource bounds Minimal residual resources that should be guaranteed
to preserve QoS levels of accepted connections
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Actual SatisfactionResource bounds
WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Path creation & maintenance Soft-QoS routing is largely inspired to AODV
Each Route Request (RREQ) packet gathers statistical information on the minimum bandwidth and maximum delay along that portion of the path
RREQ is propagated only whether bandwidth request is satisfied
The destination node back propagates a Route Reply (RREP) packet along the selected path
RREP acquaints intermediate nodes with new resource bounds and updates maximum sustainable traffic rate
Source node is required to respect the maximum sustainable traffic rate limit or to refuse the connection
WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Simulation Results
Simulation of Soft-QoS Simulation of Soft-QoS routing algorithmrouting algorithm
WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Simulation Scenario
Bluetooth Scatternet Round Robin Polling Gateways spend 50 slots in each piconet
Poisson packets arrival process Mixed packet formats with average length of 1500 bits
Delay-constrained requests
WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Gaussian Approximation Local slave-to-slave connections
in each piconet Data rate=9.6 Kbit/s 1 hop
6 hops
Gaussian approx is fairly closefairly close to empirical delay CDF
Gap increases for long-distance and high traffic connection
WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Simulation setup Target connection c1
Dr = 50 ms
r = 0.2 r = 20 kbit/s
Target connection c2
Dr = 200 ms
r = 0.9 r = 30 kbit/s
Target connection c3
Dr = 200 ms
r = 0.9 r = 20 kbit/s
Target connection c4 Dr = 50 ms r = 0.2 r = 60 kbit/s
Transversal connections Starting after 20 s, last for 10 s On average 1 request/s Random source, destination & QoS
requests Rate: 520 kbit/s
WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Satisfaction & Delay dynamics Satisfaction Delay
WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Conclusions We have proposed a basic Soft QoS routing algorithm for low-profile
ad hoc networks
Provides Soft-QoS guarantees
Requires
basic nodes’ functionalities
statistical link state monitoring (mean and standard deviation)
Does not require
service differentiation
static resource reservation
Drawbacks
Lower resource utilization
Higher rate of connection request rejection
WPMC 2003 Yokosuka, Kanagawa (Japan) 21-22 October 2003
Department of Information EngineeringUniversity of Padova, ITALY
On Providing Soft-QoS in On Providing Soft-QoS in
Wireless Ad-Hoc NetworksWireless Ad-Hoc Networks
{andrea.zanella, daniele.miorandi, silvano.pupolin}@dei.unipd.it
Andrea Zanella, Daniele Miorandi, Silvano Pupolin, Paolo Raimondi
WPMC 2003, 21-22 October 2003
Special Interest Group on NEtworking & Telecommunications