unità del politecnico di bari

DEE -Politecnico di BariDEE -Politecnico di Bari

Unità del Politecnico di BariUnità del Politecnico di Bari

Sintesi e ottimizzazione Sintesi e ottimizzazione energetica di protocolli di acceso energetica di protocolli di acceso

e trasporto in reti wireless e trasporto in reti wireless multihopmultihop

Pietro CAMARDA (Coordinatore)Gennaro BOGGIA (Ricercatore)Marcello CASTELLANO (Ricercatore)Cataldo GUARAGNELLA (Ricercatore)Orazio FIUME (Dottorando)Domenico STRICCOLI (Ricercatore)

Alfredo GRIECO (Contratto)……

DEE -Politecnico di BariDEE -Politecnico di BariSintesi e ottimizzazione energetica di protocolli di acceso e trasporto in reti wireless multihop

Ottimizzazione dello strato MAC in reti wireless Ottimizzazione dello strato MAC in reti wireless “AD-HOC”“AD-HOC” (Area Tematica 2 – Gestione delle risorse radio) (Area Tematica 2 – Gestione delle risorse radio)

Protocolli di trasporto per reti wireless “AD-HOC” Protocolli di trasporto per reti wireless “AD-HOC” (Area Tematica 4 - Protocolli di trasporto) (Area Tematica 4 - Protocolli di trasporto)

Ottimizzazioni interstrato (fase due)Ottimizzazioni interstrato (fase due)


Ottimizzazione dello strato MAC in reti AD-Ottimizzazione dello strato MAC in reti AD-HOCHOC

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


Protocolli di trasporto per reti wireless AD-Protocolli di trasporto per reti wireless AD-HOCHOC

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)


BIBD-based MAC protocols for Energy Saving in Wireless Ad

Hoc Networks

Politecnico di Bari – DEEVia E. Orabona n. 4 – 70125 Bari (Italy)

12, October, 2004 (FIRENZE).12, October, 2004 (FIRENZE).


Outline802.11 & Energy savingBIBD theoryCF-Mac ArchitectureH-MacSimulationsConclusions


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


Drawbacks of the DCF in IEEE 802.11Netwoks

Main reasons of energy expenditure:CollisionsIdle power consumption waiting to send/receive packetsIdle power consumption until a new Beacon Interval starts, when an ATIM frame is sent or received.


BIBD Theory

vrbk

)1()1( vkr

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.

Stations (v)

1 32 4 5 6 7

1

3

2

4

5

6

7

Slo

ts (b

)

Access at the 1st minislotAccess at the 1st minislot

Access at the 2nd minislotAccess at the 2nd minislot

Access at the 3rd minislotAccess at the 3rd minislot

(7,7,3,3,1)(7,7,3,3,1)


CF-Mac Architecture

RTS\CTS RTS\CTSRTS\CTS

Access Window Exchange Window

1st Minislot 3rd Minislot 2nd Minislot

Tm

Ts - Time Slot

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.


Results: channel utilization

0

0.2

0.4

0.6

0.8

1

0 5 10 15 20 25 30 35 40

k - Number of stations sharing the same slot

pu -

Pro

bab

ilit

y o

f ch

ann

el u

tili

zati

on

= 100

= 80

= 60

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

kk

u v

kvp

11

1


Results: Energy Saving

96.0%

96.5%

97.0%

97.5%

98.0%

98.5%

99.0%

99.5%

100.0%

0 5 10 15 20 25 30 35 40

k - number of station sharing the same slot

Es -

Ene

rgy

Sav

ing

[%]

= 0.001

= 0.01

= 0.1

= 0.2

= 0.4

T s

T s

T s

T s

T s

s 4.0001.0

15

100

s

m

T

sT

v

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

as vT

TE 1


Results: Efficiency

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 5 10 15 20 25 30 35 40

k - number of station sharing the same slot

h -

Eff

icie

ncy

= 0.001

= 0.01

= 0.1

= 0.2

= 0.4

T s

T s

T s

T s

T s

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

k

iii pu

1

h

s 4.0001.0

15

100

s

m

T

sT

v


H-Mac Protocol

802.11 PS based

BIBD-based schedule


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)

DEE -Politecnico di BariDEE -Politecnico di BariResults: Energy consumption

1.0E+07

1.0E+08

1.0E+09

1.0E+10

1.0E+11

0 50 100 150 200 250

Time Slot (ms)

Tot

al E

nerg

y C

onsu

mpt

ion/

Thr

ough

put

(Js/

kbit

)

DCF HL DCF LLH-MAC HL H-MAC LLCF-MAC HL CF-MAC LL

15 Stations 15 Stations

DEE -Politecnico di BariDEE -Politecnico di BariResults: Energy consumption

25 Stations25 Stations

1.0E+08

1.0E+09

1.0E+10

1.0E+11

0 50 100 150 200 250

Time Slot (ms)

Tot

al E

nerg

y C

onsu

mpt

ion

(J)


DEE -Politecnico di BariDEE -Politecnico di BariResults: Energy/Throughput


1.0E+07

1.0E+08

1.0E+09

1.0E+10

1.0E+11

0 50 100 150 200 250

Time Slot (ms)

Tot

al E

nerg

y C

onsu

mpt

ion/

Thr

ough

put

(Js/

kbit

)


DEE -Politecnico di BariDEE -Politecnico di BariResults: Energy/Throughput

25 stations25 stations

1.0E+07

1.0E+08

1.0E+09

1.0E+10

1.0E+11

0 50 100 150 200 250

Time Slot (ms)

Tot

al E

nerg

y C

onsu

mpt

ion

/ T

hrou

ghpu

t (J

s/kb

it)



Results: Delay


10

100

1000

10000

0 50 100 150 200 250

Time Slot (ms)

One

Way

Pac

ket

Del

ay (

ms)



Results: Delay


100

1000

10000

100000

0 50 100 150 200 250

Time Slot (ms)

One

Way

Pac

ket

Del

ay (

ms)



ConclusionsCF-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.


Future works

The results reported in this paper will be extended in several directions:

mobility management extension to multi-hop networksadaptive resource allocationthe support of Quality of Service


Thank You So…

…any questions?

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