POWER CONTROL-BASED CHANNEL ASSIGNMENT ALGORITHM FOR WIRELESS MESH NETWORKS
7. PERFORMANCE EVALUATION
The performance of our proposed algorithm, TICA, for MRMC WMNs is compared against a
“Single-Radio Single-Channel” (SRSC) scheme and a “Common Channel Assignment” (CCA)
scheme for multi-radio mesh nodes. In CCA scheme [2], all MRs have four radio interfaces. The
first radio on each MR is tuned to first non-overlapping channel; the second radio is tuned to
second non-overlapping channel and so on. Note that in CCA and SRSC schemes, all nodes
transmit with same the maximum power and use AODV (Ad hoc On-Demand Distance Vector)
routing protocol [10].
F. Simulation Environment
For the performance evaluation via throughput analysis, NS2 (version 2.30) [11] simulation
tool is used. Multi-interface wireless mesh nodes are created in NS2 by modifying the original
node model in NS2 using the procedure given in [12].
All radios are IEEE 802.11a radios and support 12 channels. As per the IEEE 802.11 standard
[13], RxThresh is set equal to -65 dBm in order to achieve a maximum data rate of 54 Mbps
supported by IEEE 802.11a. In order to achieve a strongly connected topology, the maximum
transmission power for all the radios is set to 27 dBm. RTS/CTS is disabled.
G. Network Topologies
Three topologies are used in the evaluation and each consists of 36 MRs distributed in an area
of 500 m × 500 m. Topology 1 is a grid and topology 2 is randomly generated while in topology 3,
called controlled random, physical terrain is divided into cells and a MR is placed randomly in
each cell.
H. Simulation Parameters in NS2
Based on CA by gateway, IEEE 802.11a channels are assigned to links between MRs and
transmission power for each radio of each MR is set accordingly. The physical (PHY) and MAC
(Medium Access Control) layer settings used for simulation are shown in Table I and Table II,
respectively.
All MRs at the periphery of network send traffic to gateway simultaneously. So, this represents
scenario in which multiple flows within mesh network interfere with each other. Each of these
nodes generates an 8 Mbps Constant Bit Rate UDP traffic stream consisting of 1024 byte packets.
They start at 1 second and do not stop until the end of simulation (600 seconds).
Table I. PHY Layer Configuration in NS2
Physical Layer Parameters
TX/RX Antenna Height (m)
Gain of TX/RX Antenna (dB)
Packet Capture Threshold (dB)
Packet Reception Threshold (watts)
Carrier Sense Threshold (watts)
Settings
3
1
10
3.16227e-10
7.91359e-11
Table II. MAC layer Configuration in NS2
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