DEE -Politecnico di Bari Unità del Politecnico di Bari Sintesi e ottimizzazione energetica di protocolli di acceso e trasporto in reti wireless multihop.

Presentazione sul tema: "DEE -Politecnico di Bari Unità del Politecnico di Bari Sintesi e ottimizzazione energetica di protocolli di acceso e trasporto in reti wireless multihop."— Transcript della presentazione:

1 DEE -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) Domenico STRICCOLI(Ricercatore) Alfredo GRIECO(Contratto) ……

2 DEE -Politecnico di Bari 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 DEE -Politecnico di Bari 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 DEE -Politecnico di Bari 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 DEE -Politecnico di Bari 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 DEE -Politecnico di Bari Outline 802.11 & Energy saving BIBD theory CF-Mac Architecture H-Mac Simulations Conclusions

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

8 DEE -Politecnico di Bari 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 DEE -Politecnico di Bari 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 DEE -Politecnico di Bari More Theory Parameters: (7, 7, 3, 3, 1) 3th player, in his first game, meets players 1, 4; in the second, meets 2, 5, and 6, 7 in the third. All players meet each other exactly once, because lambda is 1.

11 DEE -Politecnico di Bari 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.

12 DEE -Politecnico di Bari Round Robin Some unfairness among stations can arise due to the proposed mechanism that privilege the station in the early minislot, therefore a round robin rotation is needed, in each slot, to assure fairness.

13 DEE -Politecnico di Bari The probability that in a generic slot the channel is occupied is simply given by: When the i th station starts to transmit after the RTS/CTS mechanism, the total activity time (of all k stations) is: The previous event occurs with probability: Performance Evaluation Ts length of time slot and Tm of a minislot

14 DEE -Politecnico di Bari Performance Evaluation The average value of total activity time is: If all v stations are awake, the total activity time is so the energy saving: Useful time to transmit is with probability and i =1÷k, so efficiency is:

15 DEE -Politecnico di Bari Results: channel utilization The probability that in a generic slot the channel is occupied by a transmission is very close to 1.

16 DEE -Politecnico di Bari 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.

17 DEE -Politecnico di Bari Results: Efficiency The efficiency is a function of k, that increases monotonically until a constant value is reached, which is very close to 1.

18 DEE -Politecnico di Bari H-Mac Protocol 802.11 PS based BIBD-based schedule

19 DEE -Politecnico di Bari 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)

20 DEE -Politecnico di Bari Results: Energy consumption 15 Stations

21 DEE -Politecnico di Bari Results: Energy consumption 25 Stations

22 DEE -Politecnico di Bari Results: Energy/Throughput 15 Stations

23 DEE -Politecnico di Bari Results: Energy/Throughput 25 stations

24 DEE -Politecnico di Bari Results: Delay 15 Stations

25 DEE -Politecnico di Bari Results: Delay 25 Stations

26 DEE -Politecnico di Bari 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.

27 DEE -Politecnico di Bari 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

28 DEE -Politecnico di Bari Thank You So… …any questions?