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

1. First Year Results and Lessons, and Project Directions for the Second Year Marco Conti Computer Networks Dept., IIT CNR Marco.conti@iit.cnr.it http://cnd.iit.cnr.it/mobileMAN

2. Methodology 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” (*): • Integration (lack of) • Implementations/Testbeds (lack of) • 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.

3. State of the Art: open issues • 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.

4. 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?

5. Can we trust the protocols inside the simulators? 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.

6. Can we trust simulative results? real No calibration of simulators with real measurements 3. Not all 802.11 aspects are modelled, e.g., most simulators assume the same Tx range for unicast and broadcast frames. The Communication Gray Zones Problem

7. MobileMAN: Experimentation & Implementation 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.

8. MobileMAN: Integration application 1 application 2 application k middleware transport and network layer protocols cooperation model power management wireless ad-hoc technologies 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.

9. MobileMAN Status 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.

10. MANET Architecture 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.

11. MANET reference architecture Application 1 Application 2 Application n Middleware Service location, Group communication, DSM Inter-layer tasks Security Cooperation Energy Saving Applications & Middleware Transport and Network layer protocols TCP, IP routing, Forwarding, Addressing, Interconnection Networking Medium Access Control, Antennas, Power Control 802.11 Bluetooth Hyper LAN Enabling Technologies

12. Cross layers’ Dependencies in MANET Design 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 layeredarchitecture: 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.

13. Cross Layering Pros Cross Layer optimization for allnetwork 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 Awarenessat 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.

14. Cross Layering Cons • 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

15. MobileMAN Cross Layer Architecture Applications Middleware Socket API Network status (Simplified) Transport Protocol Cooperation Performability Power Management Forwarding Users’ location Routing Network Layer Enhanced Wi-Fi cards 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. MobileMAN approach to cross layering tries to balance performance optimization with protocols’ stack adatability

16. MobileMAN Cross Layering Architecture 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.

17. Directions for the Second Year Continue along the construction of a MANET following the IETF approach to be used for experimental tests (internal and with users) Refine the MobileMAN Architecture and Protocols to include the Cross Layering principle

18. MobileMAN protocol stack architecture with Cross Layering Cross-Layering Ring overlay for subject-based routing NeSt Socket-based networking Common API Middleware (Subject-Based Routing) NeSt API Berkley Sockets (stream, datagram) Transport (TCP, UDP) Network (Link-State routing, IP forwarding) IEEE 802.11 (MAC + Physical)

19. MobileMAN Cross Layering Architecture: II Year Open Issues • 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.

20. 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

21. 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

22. Registering and seizing of an abstraction NeSt register() a. Register seize() P1 1. Generate PID 2. Return PID access() b. Seize an abstraction with PID, AID and callback subscribe() • Verify callback 2. Grant or reject seizing notify() P2 monitor() • register : (void)  ProID • seize : (ProID, AbsID, CallBack())  result

23. Synchronous interaction NeSt register() a. Access an abstraction with PID, AID and Filter() seize() P1 access() • Invoke callback for AID • Apply Filter() on AID 3. Return Filter() result subscribe() P2 INTERNAL DATA notify() monitor() b. Abstract internal data in NeSt format • access : (ProID, AbsID, Filter())  result

24. Asynchronous interaction: internal events NeSt register() seize() 1. Register subscription (PID, EID) P1 access() a. Subscribe event with PID and EID subscribe() 1. Check EID on the subscription list 2. Deliver the occurrence to matching subscribers P2 Catch e notify() monitor() b. Notify event with PID, EID and info regarding the occurrence • subscribe : (ProID, EvID)  result • notify : (ProID, EvID, EvInfo)  result

25. a. Monitor event with PID, AID and Monitor() NeSt register() seize() P1 • Verify Monitor() 2. While (true) 2a. Invoke callback for AID 2b. Apply Monitor() to AID 2c. If match found notify PID access() subscribe() P2 Internal data notify() monitor() • Abstract internal data in NeSt format Asynchronous interaction • monitor : (ProID, AbsID, Monitor())  result

26. Second Year Objectives Wireless Technologies Include 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 services Include the cross-layering view at network/transport layer Design/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.

27. Second Year Objectives (cont.) 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 services Include 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

28. Questions? 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 !