M131. Designing a Scalable Routing Protocol for Wireless Sensor Networks
1. Tema proiectului
Evaluarea solutiilor de rutare actuale pentru reţele de senzori. Implementarea unui protocol de rutare pentru retele de senzori wireless.
2. Obiective
Realizarea unui studiu asupra protocoalelor de rutare pentru retelele de senzori wireless care sa aiba ca rezultat:
- identificarea claselor de algoritmi
- identificarea algoritmilor care ofera un nivel ridicat de tolerante la defecte
- identificarea algoritmilor ce duc la reducerea consumului de energie prin interschimbarea unui numar minim de mesaje
Pe baza studiului efectuat, va fi proiectat si implementat un nou protocol. Acesta poate fi construit de la 0 sau construit pornind de la un algoritm existent.
Acest algoritm va trebui sa fie optimizat pentru:
- reducerea consumului de energie – aceasta reducere se realizeaza prin minimizarea numarului si a lumgimii mesajelor trimise. Trebuie tinut cont de 2 aspecte. Pe de o parte, trebuie redusa frecventa si lungimea mesajelor, pe de alta parte trebuie sa existe un mecanism de control care sa permita detectia disparitiei nodurilor. Astfel, protocolul trebuie sa gaseasca un balans intre reusursele utilizate pentru a mentine topologia corecta, sincronizata cu schimbarile fizice ale retelei, si consumul de energie asociat cu aceasta operatie.
- detectia modificarilor retelei: daca un nod ce reprezinta o punte in cadrul grafului de transmisie a informatilor iese din retea (cade, ramane fara baterie, se defecteaza etc), nodurile care il foloseau ca punct de legatura cu restul retelei trebuie sa detecteze cat mai rapid acest lucru si sa ia 2 masuri: 1) sa nu ii mai transmita informatii; 2) sa aleaga un alt nod de legatura (daca exista). Cu cat aceaste decizii sunt luate mai rapid, cu atat se consuma mai putina energie realizand transmisii inutile.
- scalabilitate – protocolul trebuie sa fie scalabil la cel putin 100 de noduri.
3. Bibliografie
[1] Woo, A., Tong, T., Culler, D., E., Taming the underlying challenges of reliable multihop routing in sensor networks. SenSys 2003: 14-27 (http://www.cens.ucla.edu/sensys03/proceedings/p14-woo.pdf)
[2] Al-Karaki, J.N., Kamal, A.E. Routing Techniques in Wireless Sensor Networks: A survey, IEEE Wireless Communications, Vol. 11, No. 6. (2004), pp. 6-28. (http://www.ece.iastate.edu/~kamal/Docs/kk04.pdf)
[3] Alazzawi, L.K., Elkateeb, A.M., Ramesh, A., Aljuhar, W., Scalability Analysis for Wireless Sensor Networks Routing Protocols, Proceedings of the 22nd International Conference on Advanced Information Networking and Applications, 2008
[4] Oh, S., Kim, D., Kang, H., Jeong, H., SMSR: A Scalable Multipath Source Routing Protocol for Wireless Sensor Networks, Proceedings of the 6th International Conference on Ubiquitous Intelligence and Computing, 2009
[5] http://www.hindawi.com/journals/jcsnc/2008/481046.html
4. Detalii de desfasurare
- coordonator proiect: conf. dr. ing. Razvan Rughinis
- echipa: CRACIUN Eduard-Nicolae, MANOLE Catalin-Teodor, STAN Mihai
- cunostinte necesare: retelistica si algoritmi
- sala: EG106b
- program: 6 ore pe saptamana, doua semestre
5. Rezultatele primului semestru
Position Aware Routing Protocol for Wireless Sensors Networks
Routing in wireless sensors networks is still a new research area and the solutions proposed so far leave room for improvement. We hope that the protocol presented in this paper opens a new door towards achieving one of the most ambitious goals of wireless sensors networks: to know the exact position of the sensors with the best energy efficiency.
We brought a new perspective in obtaining location information: the network relies on just 3 or 4 master nodes to determine their exact position using a GPS card, while all the other sensors can compute their position based on triangulation and estimated distance to sensors that already know their location. This way the network will benefit from the advantages of location awareness and its life span will not be affected by the GPS card’s large power consumption rate.
The imperfection and unreliability of the wireless transmission environment gave us the idea to use multiple power levels for the transmission, based on the communication failures rate. For the same reason, the routes from the routing table contain the PP field, a counter for failed transmissions that allows the protocol to dynamically change the metric for each neighbor and elect the best next-hop for forwarding packets.
For an easy deployment of the sensors we designed a solution based on backup nodes. If some nodes land too close to each other we make use of this unfortunate situation to prolong the life span of the network by allowing the nodes to be in the backup mode until the main node remains with little battery. When this happens, the backup node will take over the sensing and routing tasks.
For critical situations, when the value measured by a node exceeds a certain threshold, we created a special packet type: the triggered packet. This packet allows the sensors to have longer sleeping periods, thus prolonging the network’s autonomy. A compromise can be made between the network’s life span and the frequency of new data transmissions, a compromise that can be controlled by the owner of the protocol through the sleeping period parameter.
Due to all the configurable parameters, the protocol can be used in networks with different goals and in many scenarios.
