National Research Council - Pisa - Italy

1. National Research Council - Pisa - Italy • IST - FET Initiative MobileMAN Architecture and Protocols Marco Conti Italian National Research Council (CNR) IIT Institute 2nd MobileMAN Workshop - Sophie-Antipolis 6-7 March, 2003

2. Reference Architecture

3. Enhanced Legacy MANET Architecture Existing Applications (SMS, chating, etc..) Middleware Services location Socket API TCP Cooperation Power Management Security (?) IP layer MANET Routing algorithms Wi-Fi cards Enhanced Wi-Fi cards (?)

4. MANET approach: IP centric • The problem is mainly concentrated on the IP layer and is related to “solve mobile routing problems at the IP layer” • the main reason for doing work at the IP layer is to better support heterogeneity and networked interoperability of lower layer technologies • support for a heterogeneous mix of technologies and devices is one of the great successes of IP • IP layer software development often capitalizes on the rich variety of work done within IP protocol software stacks and operating systems therefore easing development, deployment costs, and simplifying redesign and replication efforts.

5. Ad Hoc network realistic view • Networked communication dynamics favor smaller wireless networks or at least networks requiring fewer hops in order to access a fixed backbone • For example, in ad hoc networks employing omni-directional antennas, recent research • Piyush Gupta and P. R. Kumar, ``The Capacity of Wireless Networks,'' IEEE Transactions on Information Theory, vol. IT-46, no. 2, pp. 388-404, March 2000. • has shown that as the network scales (assuming it is equally likely that any pair of network nodes wish to communicate) as the number of communicating network nodes grows, the achievable throughput per node pair goes to zero • As such, the prospect of deploying very large-scale, ad hoc networks based on broadcast transmissions is not very promising.

6. Ad Hoc network realistic view (cont.) • MANET scales: • small-scale (i.e., 2-20 nodes) • moderate-scale (i.e., 20-100 nodes) • large-scale (i.e., 100+ nodes) • very large-scale (i.e., 1000+ nodes • Small-medium scale ad hoc islands •   Ad hoc islands interconnected to the Internet

7. Ad Hoc network realistic view (cont.) • MANET etherogeneity is limited • 802.11 • Bluetooth (too limited coverage area) • 802.11family is de facto the standard for WLANs • Ad hoc networking can be successful only if sufficiently dense network exists • Our view of ad hoc network: • 802.11 based small-medium scale ad hoc islands • homogeneous • small (medium) scale • Novel MobileMAN Architecture

8. Novel MobileMAN Architecture The rationale to go in this direction:Problems pointed out by measurement studies of simple 802.11 ad hoc networks: • Wi-Fi in ad hoc configurations has severe problems- TCP mechanisms made the Wi-Fi system more unstable- The 3-hop horizon for ad hoc networks made interesting          to use simpler routing mechanisms • 2, 2.5 Routing protocols, simplified TCP, cross-layers functions

9. Novel MobileMAN Architecture Proxy-based architecture for the connection to the Internet The Ad Hoc network is a subnet based on “ad hoc” protocols Applications and Middleware Proxy daemon Socket API Socket API Socket API Simplified Transport Protocol TCP Simplified Transport Protocol Subnetwork Forwarding and Routing Subnetwork Forwarding and Routing IP Wi-Fi or Enhanced Wi-Fi Subnetwork Wi-Fi or Enhanced Wi-Fi cards Proxy Ad Hoc Node

10. Applications and Middleware TCP Socket API IP Simplified Transport Protocol Subnetwork Forwarding and Routing Wi-Fi or Enhanced Wi-Fi cards Novel MobileMAN Architecture Ad Hoc Node Interconnection to Internet without proxy

11. Novel MobileMAN Architecture (Cont.) Current solutions are typically not “optimized”: solutions at one layer generally not exploit information/mechanisms available at lower layers Es. Localization services are designed independently by mechanisms already available at lower layers Our idea to exploit inter-layer coordination

12. Inter-layer coordination Example: MAC - Network Layers coordination Let us assume that the network layer through the routing mechanism has a (partial) knowledge of the network topology. We can also assume that this knowledge is typically accurate for a 1-2 hop distance The MAC layer could exploit this information to reduce the impact of phenomena such as: exposed nodes, capture phenomena etc.

13. Inter-layer coordination (cont.) Example: MAC - Network Layers coordination (Cont.) On the other hand knowledge available at MAC layer can be used to select among alternative routes It might be worth avoiding one route because a link is currently blocked at MAC level (e.g., through the RTS/CTS mechanism, etc.)

14. Inter-layer coordination (cont.) Example: Cooperation /Forwarding/Routing coordination • Let us assume that the network layer through the routing mechanism has a (partial) knowledge of the network topology. This may include • Alternative routes for a given destination • Other info on these routes (e.g., number of hops) • The Cooperation layer by using these info can try to classify the reliability/performance/cooperation along these routes. A new nearness metric can be derived

15. Inter-layer coordination (cont.) Example: Cooperation /Forwarding/Routing coordination (cont.) • Packet Forwarding can exploit the closeness metric • to select among alternative paths • to perform a load balancing among the routes • The feedbacks from this choice can be used to refine the nearness metric

16. Inter-layer coordination (cont.) Example: Forwarding/Cooperation/Transport coordination (cont.) The transport layer might use a redundant coding technique (see, e.g., FEC): a message is coded into n blocks but only k (k<n) need to be received. The redundancy level can be selected taking into account the reliability metric at the Cooperation layer Blocks can be forwarded on alternative links taking into consideration the closeness/reliability metric Finally, the results of this transmissions can be used to refine the reliability (nearness) metric.

17. Novel MobileMAN Architecture Treasure hunting (with code mobility) Shared memory Middleware Services location Socket API Cooperation/ Performability Simplified Transport Protocol Power Management Users location Forwarding Routing (2) Enhanced Wi-Fi cards