first year results and lessons, and project directions for the second year

First Year Results and Lessons, First Year Results and Lessons, and Project Directions for the and Project Directions for the Second YearSecond Year

Marco ContiComputer Networks Dept., IIT CNR

[email protected]://cnd.iit.cnr.it/mobileMAN

MobileMAN IAB meeting (Helsinki, 7 Jun 2004)

2200 papers (citeseer), but no mainstream products

More than 10 years of research but this area is far from being consolidated

Three Areas where Ad Hoc lacks “Realism” (*):

1. Integration (lack of)2. Implementations/Testbeds (lack of)3. Experimentation (lack of)

(*) Christian Tschudin, Henrik Lundgren, Erik Nordström, “Embedding MANETs in the Real World“, Personal Wireless Communications”, Proceedings of the 8th IFIP-TC6 Conference, Venice, Italy, 23-25 September 2003, Lecture Notes in Computer Science LNCS 2775.

Methodology


1. Integration (lack of)

Focus was mostly on revising routing Internet Draft. Current ID revision numbers: v13 (AODV, now an RFC), v9 (DSR), v11 (OLSR), v10 (TBRPF)

Main other areas have been analyzed (and new areas are continuously added), see (*):

- Most works focus on a single layer/issue (MAC, Routing, TCP, middleware, etc.); or

- Studies of the interation among few layers (TCP and MAC, TCP and routing, energy and topology control, …)

Lack of an overall view of MANET architecture and protocols

(*) I. Chlamtac, M.Conti, J. Liu, “Mobile Ad hoc Networking: Imperatives and Challenges”, Ad Hoc

Networks Journal, Vol.1 N.1, 2003.

State of the Art: open issues


2. Implementations/Testbeds (lack of)

Only limited hands-on experience available(typically 4 to 10 nodes, up to 37 at Uppsala)

3. Experimentation (lack of)

Internet Drafts production cycle mainly driven by simulation work: “implementations can come later, simulations tell the truth”

Few attempts to validate/calibrate simulative studies with measurements

Can we trust the protocols inside the simulators?

State of the Art: open issues


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Scenario

An IEEE 802.11 network with 50 nodes moving according to the Random Waypoint mobility model in a 1500m x 300m closed rectangular area. The nodes maximum speed is equal to 1 m/sec.

In the considered scenario there are 3 FTP sessions (1460 bytes per packet), and ten CBR sessions (512 bytes per packet).

Results

Figures show the sum of the 3 FTP-session throughput by varying the length of the pause in the Random Waypoint model

Results are highly dependent on the simulation tool.

Can we trust the protocols inside the simulators?


3. Not all 802.11 aspects are modelled, e.g., most simulators assume the same Tx range for unicast and broadcast frames.

2 Mbps data rate

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(m)

NS2QualNetrealereal

2. No calibration of simulators with real measurements

MS

FS2FS1GW

Brodcast Range

Unicast Range

Gray Zone

The Communication Gray Zones Problem

Can we trust simulative results?


Experimentation

Use of real testbeds:

• to validate the developed solutions whenever possible or, (at least),

• to calibrate/validate the simulation models to be used for architecture and protocols desgin

Implementations

• Whenever possible, hardware/software implementation of the MobileMAN solutions

• The integration of the developed solutions in a testbed.

MobileMAN: Experimentation & Implementation


The development, and validation, of effective integrated solutions for the relevant technical issues of self-organizing networks: routing and medium access control protocols, power management, security, and location.

middleware

transport andnetwork layer protocols

wireless ad-hoc technologiespow

er

man

ag

em

en

t

coop

era

tion

mod

el

application 1 application 2 application k

MobileMAN: Integration


Experimentation

• We will see some experimental results in the following presentations

Implementation

• The main activity of the second year of the project

Integration

• A preliminary integration will be performed in the last months of the II year.

MobileMAN Status


MANET IETF WG proposes a view of mobile ad hoc networks as an evolution of the Internet [1]:

• IP centric view (“solve mobile routing problems at the IP layer”), and

• use of a layered architecture

Advantages: It guarantees that the TCP/IP protocol stack can efficiently operate on a large set of heterogeneous technologies.

Drawbacks: layers independence makes difficult to fix some ad hoc networks, see for example TCP-MAC interaction problems.

MANET Architecture


MANET reference architecture

Medium Access Control, Antennas, Power Control

Transport and Network layer protocols

TCP, IP routing, Forwarding, Addressing, Interconnection

Middleware

Service location, Group communication, DSM

Application 1

Inter-layertasks

Security

Cooperation

EnergySaving

Application 2 Application n

802.11 Bluetooth Hyper LAN

Applications

&

Middleware

Networking

Enabling

Technologies


Efficient solutions for ad hoc networks require a more strict cooperation among protocols belonging to different layers [2]:

for example, from the energy management standpoint, power control and multiple antennas at the link layer are coupled with scheduling at MAC layer, and with energy-constrained and delay-constrained routing at network layer

The question is to what extent the pure layered approach needs to be modified?

• Extension of the layered architecture: layer triggers

Layer triggers are pre-defined signals to notify some events to the higher layer, e.g., failure in data delivery.

• “Violation” of the layered architecture: full cross layering design

Neglecting the layers separation principle by a joint design of the protocols

[2] A.J. Goldsmith, S.B. Wicker, “Design Challenges for Energy-Constrained Ad Hoc Wireless Networks”, IEEE Wireless Communications, Volume 9, Number 4, August 2002. pp. 8- 27.

Cross layers’ Dependencies in MANET Design


Cross Layer optimization for all network functions. Cross layering is a must for functions such as energy management, but provides benefits for all network functions.

Both local and global adaptation can be performed to adapt the system to highly variable ad hoc network conditions, and to better control the system performance

Full Context Awareness at all layers. At each layer, protocols can be designed to be aware of the network status, energy level, etc. Cross layering makes easy to achieve context awareness at the application layer.

Reduced overhead for collecting the network status information avoiding data duplication at different layers.

Cross Layering Pros


• Protocols re-design (?)

minimal re-design is desirable

• No Layers independence (?)

“spaghetti” style in protocols design must be avoided

Vikas Kawadia, P.R. Kumar, "A Cautionary Perspective on Cross Layer Design", Technical reports

Cross Layering ConsCross Layering Cons


Applications

Pow

er

Managem

en

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Enhanced Wi-Fi cards

RoutingUsers’ locationForwarding

(Simplified) Transport Protocol

Socket API

MiddlewareN

etw

ork

sta

tus

Coopera

tion

Perf

orm

abili

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Network Layer

MobileMAN Cross Layer Architecture

MobileMAN approach to cross layering tries to balance performance optimization with protocols’ stack adatability

the kernel of the architecture is a shared memory (“Network Status” in the figure) that is a repository of all the network status information collected by the network protocols. All protocols can access this memory to write the collected information, and to read information produced/collected from the other protocols.


Allows for a full compatibility with standards, as it does not touch the core functions of each layer.

Is robust to upgrading, and protocols belonging to different layers can be added/removed from the protocol stack without modifying the operations at the other layers.

For example, using the legacy TCP protocol as the transport protocol of the MobileMAN

architecture only imply that cross-layer optimizations will not occur at this layer.

It maintains all the advantages of a modular architecture.

Layer separation is achieved by standardizing the access to the Network Status.

MobileMAN Cross Layering Architecture


1. Continue along the construction of a MANET following the IETF approach to be used for experimental tests (internal and with users)

2. Refine the MobileMAN Architecture and Protocols to include the Cross Layering principle

Directions for the Second YearDirections for the Second Year


Berkley Sockets (stream, datagram)

Transport(TCP, UDP)

IEEE 802.11 (MAC + Physical)

NeStN

eSt

AP

I

Network (Link-State routing, IP forwarding)

Middleware(Subject-Based Routing)

Common API

Cross-LayeringRing overlay for subject-based routing

Socket-based networking

MobileMAN protocol stack architecture with Cross Layering


• How should the network status information managed?

• How protocols belonging to different layer access to the common information?

• Make protocols cross-layer aware

• Protocols overheads cannot be evaluated in isolation but new cross-layer metrics need to be defined.

MobileMAN Cross Layering Architecture: II MobileMAN Cross Layering Architecture: II Year Open IssuesYear Open Issues


NeSt Hypothesis

We have a language, that the NeSt and the protocols can use for:

Describing data

Writing functions to analyse/monitor data

The NeSt manages abstractions of data and events, internally maintained by protocols

Example: topology information collected at the routing layer is exported in a graph structure in the NeSt


NeSt functionalities

NeSt groups and controls all cross-layer interactions

It implements two models:Synchronous interactions, to allow data sharing among protocols

Asynchronous interactions, to allow network event subscription and notification


a. Register

b. Seize an abstraction

with PID, AID and callback

NeSt register()

seize()

access()

subscribe()

notify()

monitor()

P1

P2

1. Generate PID 2. Return PID

1. Verify callback 2. Grant or reject seizing

•register : (void) ProID

•seize : (ProID, AbsID, CallBack()) result

Registering and seizing of an abstraction


NeSt register()

seize()

access()

subscribe()

notify()

monitor()

P1

P2

a. Access an abstraction with PID, AID and

Filter()

b. Abstract internal data in NeSt

format

INTERNAL DATA

1. Invoke callback for AID

2. Apply Filter() on AID

3. Return Filter() result

•access : (ProID, AbsID, Filter()) result

Synchronous interaction


NeSt register()

seize()

access()

subscribe()

notify()

monitor()

P1

P2

a. Subscribe event with

PID and EID

b. Notify event with PID, EID and info

regarding the occurrence

Catch e

1. Check EID on the subscription list

2. Deliver the occurrence to matching subscribers

1. Register subscription (PID, EID)

•subscribe : (ProID, EvID) result

•notify : (ProID, EvID, EvInfo) result

Asynchronous interaction: internal events


NeSt register()

seize()

access()

subscribe()

notify()

monitor()

P1

P2

a. Monitor event with PID, AID and

Monitor()

b. Abstract internal data in NeSt format

Internal data

1. Verify Monitor()

2. While (true) 2a. Invoke callback for AID 2b. Apply Monitor() to AID 2c. If match found notify PID

•monitor : (ProID, AbsID, Monitor()) result

Asynchronous interaction


Wireless TechnologiesInclude the cross-layering view at datalink layer.Design and implement a full datalink layer that includes the enhanced MAC protocol for ad hoc networks as designed during the first year.

Networking servicesInclude the cross-layering view at network/transport layerDesign/Implementation of packet forwarding schemes suitable for MobileMAN. Development and testing of an ad hoc network

Co-operation Model Implementation and validation of the cooperation models and mechanisms defined during the first year.

Second Year Objectives


Middleware Adaptation of Pastry middleware for the MobileMAN environment to exploit cross layering.

Development of new solutions for P2P information delivery based on Pastry.

New applications and servicesInclude the cross-layering view at application layer

Adaptation of existing applications, identified, during the first year, to run on top of MobileMAN.

Socio-economic Model Apply the developed methodology for evaluating social, anthropological potential of MobileMAN, and provide the results for improving the technical parts.

To investigate market-based mechanisms for exploiting the self-organised paradigm

Second Year Objectives (cont.)


References

MobileMAN: Deliverable D5

M. Conti, S. Giordano, G. Maselli, G. Turi, “Cross Layering in MANET: the MobileMAN Approach”, IEEE Computer, February 2004.

M. Conti, J. Crowcroft, G. Maselli G. Turi, “A Modular Cross Layer Architecture for Ad Hoc Networks”, in “Theoretical and Algorithmic Aspects of Sensor, Ad Hoc Wireless and Peer-to-Peer Networks”, Jie Wu (Editor) CRC Press, 2004

Thank You !

Questions ?

first year results and lessons, and project directions for the second year

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