PLASMA: A New Routing Paradigm
for Wireless Multihop Networks
R. Laufer1
P. Velloso2
1University
of California, Los Angeles
Los Angeles, USA
3Universidade
L. Vieira3
2Universidade
L. Kleinrock1
Federal Fluminense
Niteroi, Brazil
Federal de Minas Gerais
Belo Horizonte, Brazil
Multiple Gateways




Total load directed to the lowest-cost gateway
Current routing models limited to unicast delivery
Prevents simultaneous use of multiple gateways
Fairness and under-utilization issues
Gateway
Internet
Gateway
Gateway
2
Our Contributions
 New routing paradigm for wireless networks
 Internet traffic can be delivered to any gateway
 Network decides both the path and gateway on the fly
 Optimal polynomial-time routing algorithm
 Load balancing
 Load split among different gateways via anycasting
 Technique for different gateway uplink bandwidths
3
Anycast Forwarding
Packet broadcast to multiple nodes simultaneously
High chance of at least one node receiving it
Node with the lowest cost forwards it on
Coordination with overhearing or ACK channels
SNIR




SNIR
Time
SNIR
Time
4
Time
Plasma Routing
 Every node forwards packets to a set of nodes
 Directed acyclic graph (DAG) to the gateways
 This DAG is called a plasma path
d1
s
d3
d2
5
Plasma Routing Challenges
 Forwarding set selection
 Few neighbors: lower receiver diversity
 Many neighbors: potentially higher costs
 Rate selection
 Lower rates: lower loss, longer range, less hops
 Higher rates: higher loss, shorter range, more hops
 Gateway set selection
 More gateways do not always reduce the routing cost
 How to choose the optimal tradeoff point?
6
Plasma Path Cost
 What is the cost of a plasma path?
 Similar to the cost in anypath routing*
 Composed of two different components
 Hyperlink cost diJ(r)
 Remaining cost DJ(r)
diJ(r)
DJ(r)
J
d1
i
d2
7
* R. Laufer et al. “Multirate Anypath Routing in Wireless Mesh Networks”, INFOCOM’09
R. Laufer et al., “Polynomial-Time Algorithms for Multirate Anypath Routing in Wireless Multihop Networks”, IEEE/ACM ToN
Plasma Cost Example
 Cost calculation
Di  diJ  DJ
1
(0.3)1.1  (1  0.3)(0.2)1.4


1  (1  0.3)(1  0.2)
1  (1  0.3)(1  0.2)
 2.3 1.2  3.5
J
.3
i
?
.2
1.1
.9
0
d1
.5
1.4
.4
0
d2
.9
8
10
.1
0
d3
Plasma Cost Calculation
 Is it better to use more nodes/gateways? No!
 Additional node always decreases hyperlink cost
 May increase remaining cost
Di  diJ '  DJ '
 1.1  5.9  7.0
J’
.3
i
?
.2
1.1
.9
0
d1
.5
1.4
.4
0
d2
.9
9
10
.1
0
d3
Plasma Routing
 Distributed and optimal routing algorithm
 Generalization of the Bellman-Ford algorithm
 Run time of O(VER  VE log V )
d1
.4
2.7
∞
0
.3
.2
.1
10.9
6.5
∞
.3
s
.2
.8
.7
.4
10
.7
5.7
5.6
∞ .1
.1
0
1.6
∞
.1
3.6
3.3
∞
2.7
∞
d2
.3
5.5
∞
.5
.2
3.0
∞
0
.3
.2
d3
Load Balancing
 Plasma already has some intrinsic load balancing
 Gateway d1 receives wij  wik  47% of the traffic
 Gateway d2 receives wil  53% of the traffic
 In general, a gateway d receives
 Load depends on delivery ratios
.3
i
.9
j
.8
.2
.9
k
.1
l
11
d1
d2
Load Balancing
 Each gateway d assigned a non-zero cost
 Higher cost has a back-pressure effect
d1
.4
2.7
3.7
10
.3
.2
.1
6.5
7.4
.3
.7
5.6 .1
9.9
10.6
3.3
2.7
8.8
.1
d2
90
.2
70
.3
.7
.4
12
1.6
6.9
.1
s
.2
.8
.3
5.5
6.5
.5
10.9
3.0
.2
d3
Simulation Scenario
 IEEE 802.11a
 Path-loss and SNIR models for the PHY layer
 500x500 m2 grid topology with 11x11 nodes
13
Plasma Throughput
98%
5.6x
2.9x
14
Plasma End-to-End Delay
2.5x
5.4x
2.2x
15
Different Uplink Bandwidths
1 Mbps
16
Conclusions
 Plasma routing
 Generalization of anypath routing to anycast delivery
 Optimal polynomial-time distributed routing algorithm
 Load balancing for different uplink bandwidths
 Simulation results
 98% throughput gain and 2.2x delay decrease
 Load balancing gives additional 63% throughput gain
17
PLASMA: A New Routing Paradigm
for Wireless Multihop Networks
R. Laufer1
P. Velloso2
1University
of California, Los Angeles
Los Angeles, USA
3Universidade
L. Vieira3
2Universidade
L. Kleinrock1
Federal Fluminense
Niteroi, Brazil
Federal de Minas Gerais
Belo Horizonte, Brazil