Joint Design of Routing and Medium Access Control for Hybrid Mobile Ad Hoc Networks

Mobile Networks and Applications (January 2007)

Presented by J.H. Su (蘇至浩 )

112/04/19OPLab, IM, NTU1

Joint Design of Routing and Medium Access Control

for Hybrid Mobile Ad Hoc Networks

Authors(1/2)


Xiaojiang (James) DuReceived the Ph.D. degrees from University of

Maryland College Park in electrical engineering.

An Assistant Professor with the Department of Computer Science, North Dakota State University, Fargo.

His research interests are wireless sensor networks, mobile ad hoc networks, wireless networks, computer networks, network security, and network management.

Authors(2/2)


Dapeng WuReceived the Ph.D. degree in electrical and computer

engineering from Carnegie Mellon University, Pittsburgh, PA, in 2003.

Has been with Electrical and Computer Engineering Department, University of Florida, Gainesville, as an Assistant Professor.

His research interests are in the areas of networking, communications, multimedia, signal processing, and information and network security.

Agenda


Introduction

Assumption of HR

Hybrid Routing Protocol

Performance Evaluation

Conclusion

Agenda


Introduction

Assumption of HR



Conclusion

Introduction (1/2)


Most existing routing protocols assume homogeneous MANETs.

Gupta and Kumar showed that per node capacity of a homogeneous wireless network is only w/√ (nlogn)W is the node transmission capacity n is the number of nodes

Introduction (2/2)


Furthermore, in many realistic ad hoc networks, nodes are hybrid.in a battlefield network

In this paper, we present a new routing protocol—Hybrid Routing (HR) protocol for hybrid MANETs.node location information is used to reduce

routing overhead

Agenda


Introduction

Assumption of HR



Conclusion

Assumption of HR (1/2)


For simplicity, we consider there are only two types of nodes in the network.Backbone-Capable nodesgeneral nodes

The main idea of HR protocol is to let most routing activities rely on B-nodes.provides better reliability and fault tolerancerouting packets via B-nodes is more efficient

than using general nodesreduces the routing overhead and latency

Assumption of HR (2/2)


The routing area is divided into several small, equal-sized squares—referred to as cells.

In HR protocol, we assume the routing area is fixed. the position of each cell is also fixed

There is a unique id for each cell.

One (and only one) B-node is elected and maintained in each cell, and each B-node has a second address.

B-node can always communicate directly with B-nodes in all nearby cells.

Agenda


IntroductionAssumption of HRHybrid Routing

Routing among B-nodesRoute DiscoveryRoute RepairDissemination of Node Location InformationElection of B-nodeHybrid MAC (HMAC)

Performance EvaluationConclusion

Routing among B-nodes (1/2)


B-nodes use their second addresses to communicate with each other.

A straight line L is drawn between the centers of cell CS and Cd.

Two border lines (blue lines) which parallel to line L with distance of W from L are drawn from CS to Cd.the value of W depends on the density of BC-nodes in

the network

All the cells that are within the two border lines are defined as routing cells.

Routing among B-nodes (2/2)


W

W

Agenda





Route Discovery (1/4)


Consider a node S wants to send a data packet to a destination node D.Case 1 : S is a B-nodeCase 2 : S is a general node

S needs to know the current location of the destination node D.

Then S determines the routing cells between S and Bd, and sends Route Request (RR) packets to B-nodes in routing cells.



The RRpacket includes the following fields:Starting_B-nodeNext_cells Routing_cells Path Destination_cell


112/04/19OPLab, IM, NTU171 2 3 4

5 6 7 8

9 10 12

13 14 16

11

S

D



If S does not receive a RP from Bs for a certain time:S will initiate a B-node elecion

If Bs does not receive a RP from Bd for a certain time:Bs will flood the RR packet to all B-nodes in the network

If Bd does not receive the Ack for a certain timeBd will hold the data packet (before receiving Ack) and

request the updated location information of node Dthen Bd can send the data packet to the B-node

closest to the new location of D

Agenda





Route Repair (1/2)


Route Repair (2/2)


The RE packet includes the following fields:Repairing_B-nodeNext_cellRouting_cellsDestination_cellDestination_ nodePath

Agenda





Dissemination of Node Location Information


When a node moves out of its previous cell, it sends a location update packet (with its new location) to the B-node in the new cell (or the nearest B-node).

All B-nodes periodically send aggregated node location information to a special B-node B0.

If B0 also moves around, then B0 needs to multicast its current location to all B-nodes

Agenda





Election of B-node (1/2)


Initially, one B-node is elected in each cell if there are BC-nodes available in the cell.

Following events Initiates the B-node election process:a B-node moves out of its current cella general node discovers there is no B-node

in the cell

Election of B-node (2/2)


The election process works as following:the leaving B-node or the general node floods

an election message to all the nodes in the cell

when a BC-node receives the election message, it broadcasts a claim message that claims it will become the B-node to all nodes in the cell (each BC-node defers a random time before its B-node claim)

if other BC-node hears a claim message during this random time, it then gives up its broadcast.

Agenda





Hybrid MAC (1/2)


The key idea is to combine time-slotted mechanism with contention based mechanism.

A large time frame is divided into three sub-framesG-to-GB-to-BB-to-G

Hybrid MAC (2/2)


Inside each sub-frame, the corresponding nodes use contention-based mechanism— IEEE 802.11b to decide which node should transmit packets.

The sub-frame length depends on the amount of traffic of each subtype.

Agenda


Introduction Assumption of HR Hybrid Routing Protocol Performance Evaluation

Experiment Setting Routing overhead under different mobility Routing overhead vs. transmission range Throughput under different traffic load Delay comparison Scalability The performance of HMAC The probability of having B-nodes Performance for different BC-node densities

Conclusion

Experiment Setting(1/3)


there are totally 20 time-slotsG-to-G sub-frame takes eight timeslotsB-to-B sub-frame takes eight time-slotsB-to-G sub-frame takes four time-slots

we present the simulations performed by distributing 100 nodes uniformly at random in an area of 1,000×1,000 m.25 Backbone-Capable (BC) nodes75 General nodes



The transmission range of a B-node and a general node is 400 and 100 m.

The side length of a cell is set as a=R/1.6.

There are 16 cells in the routing area

The width of the routing cells—W is set to 0



Each simulation was run for 600 simulated seconds.

The source sent packet of 512 b at a rate of four packets per second.

We ran each simulation ten times to get an average result for each simulation configuration.

We compared our HR protocol with AODV (Ad-hoc on demand distance vector) routing protocol.

Agenda




Conclusion

Routing overhead under different mobility


Agenda




Conclusion

Routing overhead vs. transmission range


Agenda




Conclusion

Throughput under different traffic load


Agenda




Conclusion

Delay comparison


Agenda




Conclusion

Scalability


HR-S HR-L

AODV-S

AODV-L

Agenda




Conclusion

The performance of HMAC- Throughput


The performance of HMAC- Delay


Agenda




Conclusion

Performance for different BC-node densities


Agenda


Introduction

Assumption of HR



Conclusion

Conclusion


Proposed Hybrid Routing Protocol to resolve routing problem in different type of node.

An efficient algorithm is provided to disseminate node location information among all B-nodes.

Proposed a novel HMAC protocol that can improve the efficiency of medium access in hybrid MANETs.

Conclusion


HR has very good performance, and performs much better than AODV in terms of reliability, scalability, route discovery latency, routing overhead as well as packet delay and throughput.

Documents

Joint Design of Routing and Medium Access Control for Hybrid Mobile Ad Hoc Networks