Scaling the Throughput of Wireless Mesh Networks via Physical Carrier Sensing and Two-Radio Multi-Channel Architecture Jing Zhu*, Sumit Roy*, Xingang Guo**, and W. Steven Conner** *Department of Electrical Engineering U of Washington, Seattle, WA **Communications Technology Lab Intel Corporation, Hillsboro, OR
33
Embed
Scaling the Throughput of Wireless Mesh Networks via Physical Carrier Sensing and Two-Radio Multi- Channel Architecture Jing Zhu*, Sumit Roy*, Xingang.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Scaling the Throughput of Wireless Mesh Networks via Physical Carrier
Sensing and Two-Radio Multi-Channel Architecture
Jing Zhu*, Sumit Roy*, Xingang Guo**, and W. Steven Conner**
*Department of Electrical EngineeringU of Washington, Seattle, WA
**Communications Technology LabIntel Corporation, Hillsboro, OR
Efficient, but will require new MAC (hence not backwards compatible) Still cannot do full-duplex transmission (e.g.difficult to conduct channel sensing consistently
due to channel switching) Control overhead – per-packet channel swtiching
Multi Radio: One Channel per NIC(Network Interface Card) ** Simple to implement
Each NIC channel is fixed (i.e. comes hard-coded from manufacturer) no negotiation required for channel selection
Fully compatible with legacy But costly, will not scale (number of NICs = number of channels)
Our Approach: Two Radio Multi-Channel Scale, i.e. number of NICs fixed at 2 Backwards compatible Assumptions: ad-hoc scenario, irregular but not random topology, homogenous traffic No
need to frequently update the channel allocation!
*:Jiandong LI, Zygmunt J. Haas, and Min Sheng; ``Capacity Evaluation of Multi-Channel Multi-Hop Ad Hoc Networks ''; IEEE International Conference on Personal Wireless Communications, ICPWC 2002. **: A. Adya, P. Bahl, J. Padhye, A. Wolman, and L. Zhu, A Multi-Radio Unification Protocol for IEEE 802.11 WirelessNetworks, Microsoft Research, Technical Report MSR-TR-2003-44, July, 2003.
Two-Radio Based Network Cluster
• Channel Allocation with Clustering • Each cluster is identified a common channel – i.e. all inter-cluster
communications using the default (primary) radio• Intra-cluster communications on different channels using the secondary
radio• Interference Mitigation
• Interference among co-channel clusters is minimized through an efficient channel selection algorithm – MIX (min. interference channel select).
• Interference within the cluster is prevented by Physical Carrier Sensing.• Legacy compatible: legacy APs connect to mesh via default radio.
Channel 1
Channel 2
Channel 3 DefaultMAC/PHY
SecondaryMAC/PHY
MAC Extension
IP
Framework Semi-distributed clustering channel
assignment + distributed MAC mechanisms (802.11 DCF) Semi-distributed: channel on
secondary radio is assigned by the local cluster-head within the cluster
Distributed: CSMA/CA MAC protocols
Default vs. Secondary Radio Both radios are for data
transmission The secondary radio has no
administrative functionality, such as association, authentication, etc.
The common channel on the default radio is determined a-priori.
Layer 3 (IP) routing between the nodes
Clustering(HCC)
Channel Selection (MIX)
I am Cluster Head.
Configure the 2nd PHY/MAC
Fin
d
Channel
Cluster Head is down.
Reset the 2nd PHY/MAC
Reset the 2nd PHY/MAC
Receive Channel Update Information From Cluster Head
A node is elected as a clusterhead if it is the most highly connected (has the highest number of neighbor nodes) node of all its ``uncovered" neighbor nodes (in case of a tie, lowest ID (e.g. MAC address) prevails).
A node which has not elected its clusterhead is an “uncovered” node, otherwise it is a “covered” node.
A node which has already elected another node as its clusterhead gives up its role as a clusterhead.
* M. Gerla and J.T.-C. Tsai, "Multicluster, mobile, multimedia radio network", ACM/Baltzer Journal of Wireless Networks. vol. 1, (no. 3), 1995, p. 255-265.
Clustering Procedure
Step 1: All nodes have their neighbor list ready (every node should know its neighbors, how many)
Step 2: All nodes broadcast their own neighboring information, i.e., the number of neighbors, to its neighborhood.
Step 3: A node that has got such information from all its neighbors can decide its status (clusterhead or slave)
MIX – Minimum Interference Channel Selection On-Air energy estimation per channel
t0: estimation starting time T: estimation period Ei(t): on-air energy at time t on channel i
k: Selected Channel
T
dttEE
Tt
t i
i
0
0
)(
}),...,2,1{|min(| niEEk ik
Forwarding Table (MAC Extension)
Neighbor MAC/PHY
192.168.0.2 Secondary
Neighbor MAC/PHY
192.168.0.2 Default
192.168.0.4 Secondary
Neighbor MAC/PHY
192.168.0.1 Secondary
192.168.0.3 Default
192.168.0.1
192.168.0.2
192.168.0.3
192.168.0.4
Neighbor MAC/PHY
192.168.0.3 SecondaryCluster 1
Cluster 2
An IP packet will be forwarded to default or Secondary MAC/PHY according to the forwarding table in the MAC Extension layer.
DefaultMAC/PHY
SecondaryMAC/PHY
MAC Extension
IP
Example – 10 x 10 Grid
Cluster-Head
Cluster-Slave
Transmission range = d
d: neighboring distance
2
ChannelStatus
6Number of UncoveredNeighboring Nodes
8Bits 2
00
01
10
Uncovered
Cluster Head
Cluster Member
Simulation Topology
Random, Local, and Saturate Traffic
10 x 10 Grid 802.11 b 1Mbps 3 orthogonal channels Path Loss Exponent = 3 Packet Size =1024
Bytes Dash Circle: Cluster Dark node: Cluster-Head
0
1
2
3
4
5
10
11
12
13
14
15
20
21
22
23
24
25
30
31
32
33
34
35
40
41
42
43
44
45
50
51
52
53
54
55
60
61
62
63
64
65
71
72
73
74
75
76
91
92
93
94
95
96
81
82
83
84
85
866
7
8
9
16
17
18
19
26
27
28
29
36
37
38
39
46
47
48
49
56
57
58
59
66
67
68
69
77
78
79
70
97
99
99
90
87
88
89
80
Channel 1 Channel 2
B1 B2 B3 B4 B5 B6 B7 B8 B9 B10
A1 A2 A3 A4 A5 A6 A7 A8 A9 A10
C1 C2 C3 C4 C5 C6 C7 C8 C9 C10
Tracing One-Hop Aggregate Throughput
The new multi-channel and two radio architecture achieves 3X performance, compared to a traditional single-channel and single-radio mesh.
Clustering Multi-Channel and Two-Radio Architecture
Th
rou
gh
pu
t (b
ps)
Time (sec.)
Throughput Distribution
Location-dependent fairness problem : Links Ai experience worse interference environment than links Bi and Ci, leading to the oscillation of the throughput distribution.
Future Work: How Physical Carrier Sensing could mitigate the location dependent fairness problem?
0 100 200 300 400 500 600 700
100
1000
10000
100000 C10C9C8
C7
C6
C5C4C3C2C1 B10
B9
B8
B7B6B5
B4B3B2B1
A10
A9
A8
A7
A6A5
A4A3
A2
A1
On
e-H
op
Th
rou
gh
pu
t (b
ps)
Link
Clustering Multi-Channel and Two-Radio Mesh Traditional Single-Channel and Single-Radio Mesh
200m x 200m 100 nodes Random Topology
Performance Comparison in Random Topology
a) Tracing Aggregate Throughput b) Throughput Distribution
Performance gain of aggregate throughput is almost 3x (10Mbps vs. 3.5Mbps)
0 100 200 300 400 5000
1M
2M
3M
4M
5M
6M
7M
8M
9M
10M
Data Rate = 1MbpsPacket Size = 1024 BytesPath Loss Exponent = 3
Traditional Single-Channel and Single-Radio Mesh
Clustering Multi-Channel and Two-Radio Architecture
Thr
ough
put
(bp
s)
Time (sec.)
100 200 300 400
100
1000
10000
100000
On
e-H
op T
hro
ugh
put (
bps)
Link
Clustering Multi-Channel and Two-Radio Mesh Traditional Single-Channel and Single-Radio Mesh