Convergecast with MIMOConvergecast with MIMO

Luoyi Fu, Yi Qin, Xinbing WangDepartment of Electronic Engineering

Shanghai Jiao Tong University, China

Xue LiuDepartment of Computer Science and Engineering

University of Nebraska Lincoln, USA

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OutlineOutline IntroductionIntroduction

MotivationMotivation ObjectivesObjectives

ProgressProgress Cooperative MIMO Schemes in Static NetworksCooperative MIMO Schemes in Static Networks Throughput and Delay in Static NetworksThroughput and Delay in Static Networks Cooperative MIMO Schemes in Mobile NetworksCooperative MIMO Schemes in Mobile Networks Throughput and Delay in Mobile NetworksThroughput and Delay in Mobile Networks DiscussionDiscussion

Multicast Hierarchical Cooperation Presentation 3

MotivationMotivation

Most works focus on Most works focus on unicastunicast or or multicast multicast while converge-while converge-cast is relatively new.cast is relatively new.

Some relative existing work about converge-cast focuses on Some relative existing work about converge-cast focuses on the traffic in sensor networks where all nodes flow data to a the traffic in sensor networks where all nodes flow data to a single sink. However, a wide range of applications require single sink. However, a wide range of applications require multiple such converge-cast session in the network.multiple such converge-cast session in the network. Machine failure diagnosisMachine failure diagnosis pollutant detection supply chain management

Stringent capacity-delay requirementsStringent capacity-delay requirements imposed on imposed on Converge-cast.Converge-cast.

Multicast Hierarchical Cooperation Presentation 4

Motivation (cont’)Motivation (cont’)

Vast space of improvement on throughput for converge-cast Vast space of improvement on throughput for converge-cast due to its convergent property.due to its convergent property.

Converge-cast can be treated as a generalized reversed Converge-cast can be treated as a generalized reversed “multicast”.“multicast”.

HierarchicalHierarchical Cooperative MIMOCooperative MIMO has been shown to achieve has been shown to achieve a linear throughput scaling for unicast [14,Özgϋr] and a linear throughput scaling for unicast [14,Özgϋr] and multicast [13,Hu].multicast [13,Hu].

Multicast Hierarchical Cooperation Presentation 5

ObjectiveObjective

In our work, we focus onIn our work, we focus on converge-cast scaling lawsconverge-cast scaling laws in both static in both static and mobile ad hoc networks. and mobile ad hoc networks.

We jointly consider converge-cast traffic with cooperative MIMO We jointly consider converge-cast traffic with cooperative MIMO schemes. schemes. 1. How to schedule converge-cast traffic to optimize the 1. How to schedule converge-cast traffic to optimize the throughput in static networks, using MIMO?throughput in static networks, using MIMO?

2. How to schedule converge-cast traffic to optimize the 2. How to schedule converge-cast traffic to optimize the throughput in mobile networks, using MIMO?throughput in mobile networks, using MIMO?3. Delay performance when achieving optimal throughput? And 3. Delay performance when achieving optimal throughput? And the corresponding delay-throughput tradeoff?the corresponding delay-throughput tradeoff?4. Relationship between our achieved converge-cast results and 4. Relationship between our achieved converge-cast results and those in other traffic patterns?those in other traffic patterns?

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OutlineOutline IntroductionIntroduction

MotivationMotivation ObjectivesObjectives

ProgressProgress Models and DefinitionsModels and Definitions Cooperative MIMO Schemes in Static NetworksCooperative MIMO Schemes in Static Networks Throughput and Delay in Static NetworksThroughput and Delay in Static Networks Cooperative MIMO Schemes in Mobile NetworksCooperative MIMO Schemes in Mobile Networks Throughput and Delay in Mobile NetworksThroughput and Delay in Mobile Networks DiscussionDiscussion

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Models and DefinitionsModels and Definitions

Network Model: An Ad Hoc network where n nodes are Network Model: An Ad Hoc network where n nodes are randomly positioned in a randomly positioned in a unit squareunit square..

Traffic Pattern: n destinations with each one corresponding Traffic Pattern: n destinations with each one corresponding to k randomly and independently chosen sources. to k randomly and independently chosen sources. ((converge-cast)converge-cast)

Communication model: Physical layer model.Communication model: Physical layer model.

The channel gain between node i and j given byThe channel gain between node i and j given by

The signal received by node i at time t given byThe signal received by node i at time t given by

[ ]/2[ ] ijj t

ij ijh t Gd e

[ ]

[ ] [ ] [ ] [ ] [ ]i ij j i ij T t

Y t h t X t Z t I t

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Models and Definitions Models and Definitions (cont’)(cont’)

Definitions:Definitions:

Throughput:Throughput: Denote Denote m(t)m(t) as the number of packets (bits) as the number of packets (bits) from sources that a destination receives in from sources that a destination receives in tt time slots. Then time slots. Then the long-term per-node throughput is defined as the long-term per-node throughput is defined as ::

The The aggregate throughputaggregate throughput is is

Delay:Delay: The time a destination takes to receive all the packets The time a destination takes to receive all the packets from its corresponding from its corresponding kk sources. sources.

( )liminft

m t

t

n

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Cooperative MIMO Scheme in Static Cooperative MIMO Scheme in Static NetworksNetworks Cooperative MIMO Scheme 1:Cooperative MIMO Scheme 1:

Preparing for cooperation with Preparing for cooperation with

recursionrecursionMulti-hop MIMO TransmissionMulti-hop MIMO Transmission

Cooperative Reception (each Cooperative Reception (each

destination in the cluster can receivedestination in the cluster can receive

packets at layerpackets at layer ii

/i i it k n

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Cooperative MIMO Scheme in Static Cooperative MIMO Scheme in Static Networks (cont’)Networks (cont’)

An example of step 2 in cooperative MIMO scheme 1An example of step 2 in cooperative MIMO scheme 1

Convergecast: 3 sources per destinationConvergecast: 3 sources per destination

The yellow cell is the one where The yellow cell is the one where destinationdestination is located. is located.

The red cells are the ones where The red cells are the ones where sourcessources are located. are located.

Red parts in the cell Red parts in the cell

indicates the indicates the

percentage of the percentage of the

number of number of active active

nodes in this source nodes in this source

cell. cell.

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Cooperative MIMO Scheme in Static Cooperative MIMO Scheme in Static Networks (cont’)Networks (cont’)

9-TDMA scheme is adopted to avoid interference.9-TDMA scheme is adopted to avoid interference.

The yellows cells can be The yellows cells can be

active concurrently.active concurrently.

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Throughput and Delay for Static NetworksThroughput and Delay for Static Networks

In static network, by adopting Cooperative MIMO scheme 1, we can In static network, by adopting Cooperative MIMO scheme 1, we can

achieve an aggregate throughput of achieve an aggregate throughput of

with the delay ofwith the delay of

2 2 1

2 1 2 1

h

h hn k

2 2

2 2

2 4 3 2 2 1 1

2 1 2 1 2 2

2 2 4 3 1

2 1 2 1 2 2

E

h h h h

h h h

h h h h

h h h

n k k n

T

n k k O n

Throughput and delay

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Cooperative MIMO Scheme in MANETsCooperative MIMO Scheme in MANETs

Nodes move according to Nodes move according to i.i.d.i.i.d. mobility model. mobility model.

The network is divided into c cells in the way that each cell The network is divided into c cells in the way that each cell contains M nodes on average.contains M nodes on average.

9-TDMA strategy is adopted again to avoid interference of 9-TDMA strategy is adopted again to avoid interference of nearby transmission.nearby transmission.

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Cooperative MIMO Scheme in MANETsCooperative MIMO Scheme in MANETs

An illustration of transmission in an active cell in cooperative MIMO An illustration of transmission in an active cell in cooperative MIMO

scheme 2scheme 2

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Throughput and Delay for MANETsThroughput and Delay for MANETs

In MANETs, by adopting Cooperative MIMO scheme 2, we can achieve In MANETs, by adopting Cooperative MIMO scheme 2, we can achieve

the per-node throughput and delay ofthe per-node throughput and delay of

1, log 1

log

1 , 1

N

N

E D n kn

E D k k

Throughput and delay

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DiscussionDiscussion

Delay-Throughput TradeoffDelay-Throughput Tradeoff

Static networks:Static networks:

2 2

2 2

2 4 4 2 2 1

2 1 2 1 2 2

2 1 4 2 1

2 1 2 1 2 2

h h h h

h h h

h h h h

h h h

n k k n

n k k O n

MANETs:MANETs: 2M k Optimal network divisionOptimal network division

k

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Discussion (cont’)Discussion (cont’)

Results extended to unicast, multicast and broadcast under our schemes.Results extended to unicast, multicast and broadcast under our schemes.

Discussion (cont’)Discussion (cont’)

Comparison with Previous Work and GeneralizationComparison with Previous Work and Generalization

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ConclusionConclusion

Our cooperative MIMO scheme in static Our cooperative MIMO scheme in static networks breaks the bottleneck and can networks breaks the bottleneck and can achieve an aggregate throughput of order 1.achieve an aggregate throughput of order 1.

Our cooperative MIMO scheme in MANETs Our cooperative MIMO scheme in MANETs can achieve a per-node throughput of can achieve a per-node throughput of ΘΘ(1) (1) while the delay is reduced to while the delay is reduced to ΘΘ(k).(k).

Our results well cover other traffic patterns and Our results well cover other traffic patterns and act as a generalization.act as a generalization.

Thank you !Thank you !

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