thesis author: shan gong supervisor:sven-gustav häggman
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S-72.158 Master’s thesis seminar 8th August 2006
QUALITY OF SERVICE AWARE ROUTING PROTOCOLS IN MOBILE AD HOC NETWORKS Thesis Author: Shan Gong
Supervisor: Sven-Gustav Häggman
Outlines
Ad Hoc Networks QoS (Challenge of implementing QoS in a
d hoc networks, QoS metrics, QoS metric calculation)
AODVAccess admission control in QAODV QAODVSimulation Environment and Results
Mobile Ad hoc networks
The application of mobile ad hoc networks becomes more and more popular.
Applications of Mobile Ad Hoc Networks (Military Applications, Emergency Operations, Wireless Mesh networks, Wireless sensor networks).
QoS
“Quality of Service is the performance level of a service offered by the network to the user”.
QoS considered in this thesis work: low end to end delay (e.g. real time traffics)
Challenge of QoS in ad hoc networks
Dynamically varying network topology Lack of precise state information Shared radio channel The resources such as data rate, battery
life, and storage space are all very limited in ad hoc networks.
QoS metrics
Additive metrics (end to end delay)Concave metrics (data rate)Multiplicative metrics. (link outage
probability)The generally used metrics for real time
applications are data rate, delay, delay variance (jitter), and packet loss.
Calculation for locally available data rate
Method 1: Transmission range = Carrier sensing range
Case 1 is the data rate used by node i for receiving data.
Case 2 is the data rate consumed by neighbors who are receiving.
Case 3 is the data rate consumed by neighbors who are sending.
Case3
Nk,Njjk
Case2
Njj
Case1
iii
iii
)xZZ(Rate DataRate Data Available
Calculation for local available data rate
Method 2: Carrier sensing range is more than twice of the transmission range (more realistic)
Data Rate =(N*S*8)/T
The used data rate is the sum of the sent, received and sensed data rate
AODV routing protocol
ReactiveRREQ (broadcast) and RREP (unicast)RERR
Access Admission Control
Available bandwidth ? Required bandwidth
Required data rate at each node Method 1 carrier sensing range = transmission rangeWith a N-hop route, the source and destination nodes should satisfy ABi>=2r, the second and N-1 nodes ABi >=3r and the intermediate nodes ABi >=4r. Here, r is the required data rate requirement and ABi is the available data rate at node i. N-1 node is the node on the path which is next to the destination node.
EDCBA
Required data rate at each node
Method 2 carrier sensing range >= 2* transmission range
The contention count is calculated as follows If hreq > 2 hreq = 2
otherwise hreq=hreq If hrep > 3 hrep = 3
otherwise hrep=hrep
CC = hreq + hrep
Required data rate at each node Method 2 carrier sensing range >= 2* transmission range Example
1
2
3
4
5
6
7
Maximum data rate Vs. Hops of a route
Maximum data rate
0
0,5
1
1,5
2
2,5
3
3,5
4
0 2 4 6 8 10 12
Contention Count
Max
imu
m d
ata
rate
QAODV routing protocol-draft
Session IDMaximum delay extension fieldMinimum data rate extension field
Node satisfying these requests could broadcast the RREQ further
List of sources requesting QoS guarantees
AODV vs. QAODV
Recv RREQ
Recv RREP
Enough Data rate?
Broadcast RREQ
Forward RREP
Enough Data rate?
Drop RREQ
Drop RREP
Periodically check Available Data rate
Available data rate >0
Do nothing
Send ICMP_QoS_Lost
Recv ICMP_QoS_ Lost
Whether I am the source node
Forward ICMP_QoS Lost
Stop traffic
Example for QAODV—periodic check for available data rate
1
0
3
2600 m
150 m
33
Move direction of Node 3
550 m (Interference range)
Traffic stopped
Scenario
Simulations with both AODV and QAODV
Performance metrics
Average end to end delayPacket Delivery Ratio (PDR) Normalized Overhead Load (NOL) Route finding time of the first route
Simulation Environment
The channel type is “wireless channel” radio propagation model is “two ray ground”. MAC layer based on CSMA/CA as in IEEE
802.11 is used with RTS/CTS mechanism. The data rate at physical layer is 11 Mbps. Queue type is “drop tail” the maximum queue length is 50. Routing protocols are the AODV and the
QAODV. The transmission range and carrier sensing
range are 250 m and 550 m respectively.
Specific Scenarios for Simulations.
The area size is 700 m * 700 m 20 nodes in this area. Every experiment will be run 1000 s in total. (500 s is added at the
beginning of each simulation to stabilize the mobility model.) Each data point in the results represents an average of 10 trails
with same traffic model but different randomly mobility scenarios.
For fairness comparisons, same mobility and traffic scenarios are used in both the AODV and the QAODV routing protocols.
In the following set of simulations, a group of data rates ranging from 50 kbps to 1800 kbps is applied.
The mobility scenario is with a pause time of 10 seconds and the maximum node speed of nodes is 1 m/s.
Traffic pattern
Average end to end delay
Packet Delivery Ratio
Normalized Overhead Load
Time used to find the first route--First traffic flow
0
0,05
0,1
0,15
0,2
0,25
0,3
0,05 0,3 0,6 0,9 1,2 1,5 1,8
Data rate (Mbps)
Tim
e d
ura
tio
n (
seco
nd
)
AODV - traffic flow 1
QAODV - traffic flow 1
Time used to find the first route
Time used to find the first route--Second traffic flow
0
10
20
30
40
50
60
70
80
0,05 0,3 0,6 0,9 1,2 1,5 1,8
Data rate (Mbps)
Tim
e d
ura
tio
n (
seco
nd
)
AODV - traffic flow 2
QAODV - traffic flow 2
The first traffic flow 553 s ~ 774 s.
The second traffic flow 680 s ~ 780 s.
Summary and Conclusions
QAODV outperforms AODV in terms of end to end delay
Constrain the packets which might be useless to the network
More routing packets are sent (brings problem when node density is high)
More QoS metrics could be added to the routing protocol (delay, packet loss)
Thank you
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