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Unità del Politecnico di Bari

Unità del Politecnico di Bari. Sintesi e ottimizzazione energetica di protocolli di acceso e trasporto in reti wireless multihop Pietro CAMARDA (Coordinatore) Gennaro BOGGIA (Ricercatore) Marcello CASTELLANO (Ricercatore) Cataldo GUARAGNELLA (Ricercatore) Orazio FIUME (Dottorando)

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Unità del Politecnico di Bari

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  1. Unità del Politecnico di Bari Sintesi e ottimizzazione energetica di protocolli di acceso e trasporto in reti wireless multihop Pietro CAMARDA (Coordinatore) Gennaro BOGGIA (Ricercatore) Marcello CASTELLANO (Ricercatore) Cataldo GUARAGNELLA (Ricercatore) Orazio FIUME (Dottorando) Domenico STRICCOLI (Ricercatore) Alfredo GRIECO (Contratto) ……

  2. Sintesi e ottimizzazione energetica di protocolli di acceso e trasporto in reti wireless multihop • Ottimizzazione dello strato MAC in reti wireless “AD-HOC” (Area Tematica 2 – Gestione delle risorse radio) • Protocolli di trasporto per reti wireless “AD-HOC” (Area Tematica 4 - Protocolli di trasporto) • Ottimizzazioni interstrato (fase due)

  3. Ottimizzazione dello strato MAC in reti AD-HOC • Ottimizzazione degli schemi MAC utilizzati nelle reti “Ad Hoc” basate sullo standard 802.11 • Sintesi e analisi di architetture distribuite basate su BIBD (Balanced Incomplete Block Design) per ottimizzare i periodi di attività/inattività(Doze) delle stazioni

  4. Protocolli di trasporto per reti wireless AD-HOC • Studio e simulazione di varianti del TCP, idonee per reti “Ad Hoc” multihop (Predisposizione software di analisi e primi risultati) • Meccanismi interstrato • Paradigma end to end • Ecc. • in grado di migliorare: • Prestazioni • Efficienza energetica • …… • Ottimizzazione di protocolli per servizi “real time” basati su UDP (voce su IP, Video streaming, ecc.) (in corso di impostazione)

  5. BIBD-based MAC protocols for Energy Saving in Wireless Ad Hoc Networks Politecnico di Bari – DEE Via E. Orabona n. 4 – 70125 Bari (Italy) 12, October, 2004 (FIRENZE).

  6. Outline • 802.11 & Energy saving • BIBD theory • CF-Mac Architecture • H-Mac • Simulations • Conclusions

  7. Energy constrains • Mobile devices need power. • Batteries have finite capacity. • To increase the yield from a battery: • Make it bigger. • Reduce its drain.

  8. Drawbacks of the DCF in IEEE 802.11Netwoks Main reasons of energy expenditure: • Collisions • Idle power consumption waiting to send/receive packets • Idle power consumption until a new Beacon Interval starts, when an ATIM frame is sent or received.

  9. BIBD Theory The decision problem is to determine if it is possible for v stations to be awake in r slots, each shared by k stations, where b is the comprehensive number of slots in such a way that any two stations turn on their radio in the same group at most once. (7,7,3,3,1)

  10. CF-Mac Architecture The generic time slot is divided in two parts: an access window and a data exchange window. The access window contains k minislots, each one assigned to one of the k stations that share the slot, while the other (v-k) are in doze state. If one of k station has scheduled traffic to transmit, it sends a RTS frame to the destination station, which replies, if is one of other (k-1) stations, with a CTS frame. Then, the transmission starts immediately and the two stations can use the remaining time of time slot to exchange data.

  11. Results: channel utilization The probability that in a generic slot the channel is occupied by a transmission is very close to 1.

  12. Results: Energy Saving The energy saving function decreases monotonically with k until a constant value as reached, and it is insensitive to Ts other then 1ms.

  13. Results: Efficiency The efficiency is a function of k, that increases monotonically until a constant value is reached, which is very close to 1.

  14. H-Mac Protocol • 802.11 PS based • BIBD-based schedule

  15. Computer Simulations: Assumptions • Limited geographical coverage of the network • Single Hop • Negligible mobility • Set of parameters (25,30,6,5,1) (15,15,5,5,3)

  16. Results: Energy consumption 15 Stations

  17. Results: Energy consumption 25 Stations

  18. Results: Energy/Throughput 15 Stations

  19. Results: Energy/Throughput 25 stations

  20. Results: Delay 15 Stations

  21. Results: Delay 25 Stations

  22. Conclusions • CF-Mac and H-Mac protocol have been designed starting from the theory of BIBD • Their performance has been evaluated by computer simulations. • Results have shown that these schemes are able to provide a good energy saving preserving the transmission efficiency, moreover CF-Mac is more suitable for time-constraint traffics.

  23. Future works The results reported in this paper will be extended in several directions: • mobility management • extension to multi-hop networks • adaptive resource allocation • the support of Quality of Service

  24. Thank You So… …any questions?

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