Effect of a New Channel Assignment Strategy on Multihop Wir
eless Networks
Futoshi Tasaki, Fumito Uta, Hiroshi Tamura, Masakazu Sengoku, and Shoji Shinoda
IEICE Transaction on Communication, May 2004Special Section on Mobile Multimedia Communications
Outline
• Introduction• Preliminaries• Channel assignment strategies
– Strong edge coloring– Edge coloring based on degree of
interference
• Simulation and considerations• Conclusions
Introduction
• In the multihop wireless network, each terminal communicates to other terminals using– Time slot (TDMA)– Carrier (FDMA)– Code (CDMA)
• Cochannel interference may occur, channels cannot assigned randomly
Preliminaries
• Preconditions– No obstacle– Only light-of-sight links– Non-directed antenna– The same transmission power– GPS
Preliminaries
• Definitions terminal
Communication edge
Interference edge
Strong Edge Coloring
• Every two edges of distance at most two receive different colors
5 colors is needed
Edge Coloring Based on Degree of Interference
yx II
C
Signal strength
Signal strength oftwo interferences
Edge Coloring Based on Degree of Interference
Strict Interference Model
41
40
1
1
d
d
I
CCIR
42
40
1
1
d
d
I
CCIR
43
40
1
1
d
d
I
CCIR
44
40
1
1
d
d
I
CCIR
Strict Interference Model
• Because d1 is the smallest in d1, d2, d3 and d4, C1/I1 is the smallest value in the four CIR– Other three CIRs can be neglected
Strict Interference Model
Simple Interference ModelRM: the maximum distance between 2 terminals which can communicate
D: two terminal pairs should be away when using a same channel
Simple Interference Model
The distance between two adjacent terminals
is 1 unit
After inserting the interference edges
Simulations
• Mesh network–
– The ratio of rasgn means the efficiency of a channel assignment, a smaller rasgn is effective
Simulations
Simulations
• General mesh network (random topology)
Simulations
Consideration of Channel Assignment Algorithm
Consideration of the Number of Channels
Conclusion
• Strict Interference Model is more effective
• Edge-length selection algorithm is effective than random ordering
• Issues of mobility should be considered in the future
Thank you!!
