Channel%20Assignment%20for%20WLAN%20by%20Considering%20Overlapping%20Channels%20in%20SINR%20Model

1
Channel Assignment for WLAN by Considering
Overlapping Channels in SINR Model

• Kunxiao Zhou and Xiaohua Jia
• City University of Hong Kong

2
Outlines

• Introduction
• Related work
• Problem formulation
• Proposed solution
• Simulation results
• Conclusion

2
3
Introduction

• Channel assignment
• Wireless Local Area Networks (WLANs)
• Access points (APs), clients
• Basic service set (BSS)
• Assign channels to BSSs
• Partially overlapping channels (802.11b)
• 11 partially overlapping channels
• 3 non-overlapping (orthogonal) channels
• SINR model
• Accumulative nature of interference
• Most of combinatorial optimization techniques
  based on protocol model are not applicable

3
4
Related work

• A. Mishra, V. Shrivastava, S. Banerjee, and W.
  Arbaugh, Partially overlapped channels not
  considered harmful, SIGMetrics/Performance,
  2006, pp. 6374.
• Interference of overlapping channels
• Communication btwn two nodes by using overlapping
  channels
• Y. Cui, W. Li, and X. Cheng, Partially
  overlapping channel assignment based on node
  orthogonality for 802.11 wireless networks,
  Mini-Conference at IEEE INFOCOM, 2011.
• interference model two nodes interfering or not
  depends on channel distance and physical distance
  bwtn two nodes (i.e. node orthogonality)
• A. Mishra, S. Banerjee, and W. Arbaugh, Weighted
  coloring based channel assignment for wlans, in
  ACM Sigmobile MC2R, 2005
• ADJ-minmax and ADJ-sum

4
5
Problem Formulation

• Infrastructure-based IEEE 802.11 WLAN,

5
6
Problem Formulation (contd)

• W w1,,wm set of APs U u1,, un set of
  clients
• F f1, f2, , fk set of overlapping channels
• BSS AP and its associated clients
• G(U ? W, E) , (u, w) ? E client u connects to AP
  w
• ?(v,u) overlapping degree btwn channels of node
  v and u.
• Channel overlapping degree

6
7
Problem Formulation (contd)

• Data rate
• The throughput of a BSS
• Throughput of the system

7
8
Problem Formulation (contd)

• Total interference of u received from all APs
• Total interference of all clients in the system
• Maximize the system throughput is equivalent to
  minimizing system total interference

8
9
Algorithm Design

• Interference analysis
• Interference caused by AP v to client u (u
  S(v))
• Interference by AP v to all clients in a BSS Bw,
• We only consider downlink case,

9
10
Algorithm Design (contd)

• Fig. 2, weighted interference graph GI(VI,EI)

10
11
Algorithm Design (contd)

• Total weights of all edges in GI(VI,EI) ,
• The total weight of all edges in GI is equal to
  the total interference of the system.
• Our problem is converted to minimizing the total
  weight of all edges in GI(VI,EI)

11
12
Algorithm Design (contd)

• Heuristic method

12
13
Simulation Results (throughput)
13
14
Simulation Results (service ratio)
14
15
Simulation Results (per-user throughput)
15
16
Simulation Results (channel utilization)
16
17
Conclusions

• Studied channel assignment by considering
  partially overlapping channels in SINR model
• Converted the maximal throughput problem to
  minimizing total edge weight of the interference
  graph
• Proposed a heuristic method
• Channel overlapping attenuation coefficient is a
  major factor to affect the channel utilization.

17
18

• Thanks!
• Q A

18