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On-demand QoS routing

指導教授：石貴平報告學生：莊宗翰

報告日期： 2002/06/27

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Outline

Introduction Definition And Model

– TDMA Channel Model– Time Slot Selection Lemma– Bandwidth Calculation

QoS Routing Protocol– Data Structure– Slots Selecting Method– Our Protocol

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Introduction

An on-demand QoS routing protocol for ad hoc networks. Assume a TDMA channel model within our network

environment. By recording only 1-hop neighbors' information in each

host to avoid hidden-terminal and exposed-terminal problems for finding a bandwidth reservation route.

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TDMA Channel Model

The TDMA frame structure used in this paper.

Assume a simpler TDMA-based channel model. Assume one single common channel shared by all hosts. The channel is time-framed.

TDMA Frame TDMA Frame

Control Phase Control PhaseData Phase Data Phase

Slot 1 Slot 2 Slot s

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Time Slot Selection Lemma

Slot t is not yet scheduled to send or receive in neither sender nor receiver.

For any 1-hop neighbor host of sender, slot t is not scheduled to receive in it.

For any 1-hop neighbor host of receiver, slot t is not scheduled to send in it.

A B C[ t ] [ t ]

A B C[ t ] [ t ]

XD

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Bandwidth Calculation

BW(X, Y) = Free_Slots(X)∩Free_Slots(Y) ∩NNR_Slots(X)∩NNS_Slots(Y)

– Free_Slots(host)

– NNS_Slots(host)

– NNR_Slots(host)

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Bandwidth Calculation (Cont.)

Free_Slots(A) = {0,1,4,5,8,9} Free_Slots(B) = {0,1,2,4,5,6,8}

NNR_Slots(A) = {1,4,5,7,8} NNS_Slots(B) = {1,3,4,5}

∴ BW(A, B) = {0,1,4,5,8,9}∩{0,1,2,4,5,6,8}∩{1,4,5,7,8}∩{1,3,4,5}

= {1,4,5}

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Data Structure

Slots Information Table (SIT)– SITx [ 1…h , 1…s ]

RREQ(S, D, id, B, sender, route_path, next_hosts) RREP(S, D, id, route_path)

– route_path={ source, ( h1,s1 ), ( h2,s2 ), …, ( hi,si ) }

– next_hosts={ ( h1,s1 ), ( h2,s2 ), …, ( hk,sk ) }

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Our Protocol

Route Request Destination Route Reply

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Route Request

h o s t y r e c e i v e R R E Q ( S ,D , i d ,b , x , P AT H , N H x )

i f r e c e i v e d b y ( S ,D , i d )

i f h o s t y i n N xH

Y e s

N o

c h e c k a l l s l o t s t i n N x ( x y )H →c h e c k a l l n e i g h b o r s o f y

i f s l o t t i s n o ts c h e d u l e d i n s e n d

s l o t t c a n u s e i n x y →T r u e

i f t h e n u m b e ro f s l o t s c a n u s e > = b

c h o i c e s l o t s ( n u m b e r o f s l o t s = b )a d d y & s l o t s i n P A T H , S I T y _ t e m p

N o

Y e s

T r u e

c h e c k a l l n e i g h b o r s n o f y

i f s l o t t i s n o ts c h e d u l e d i n s e n d &

r e c e i v e i n y & n

s c h e d u l e d i n r e c e i v e i n a l ln e i g h b o r s o f y

c h e c k a l l s l o t s t

T r u e

i f s l o t t i s n o t

T r u e s l o t t c a n u s e i n y n→

i f t h e n u m b e ro f s l o t s c a n u s e > = b

T r u e h o s t n & s l o t s a d d i n N yH

i f N y 0H ≠

T r u e

R R E Q ( S , D , i d ,b ,y ,P AT H , N H y )

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Destinationc h e c k a l l s l o t s t i n N x ( x D )H →

c h e c k a l l n e i g h b o r s o f D

i f s l o t t i s n o ts c h e d u l e d i n s e n d

s l o t t c a n u s e i n x D →T r u e

i f t h e n u m b e ro f s l o t s c a n u s e > = b

c h o i c e s l o t s ( n u m b e r o f s l o t s = b )a d d D & s l o t s i n P AT H , S I T d _ t e m p

T r u e

s e n d R R E P ( S , D , i d , P AT H ) t o S

R R E Q ( S , D , i d ,b ,x , PA T H ,N H x )

i f r e c e i v e d b y ( S ,D , i d )

i f h o s t D i n N xH

Y e s

N oN o

Y e s

d e s t i n a t i o n D r e c e i v e

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Route Reply

h o s t y r e c e i v e R R E P ( S ,D , i d ,P A T H )

m o d i f y S I T y

b r o a d c a s t S I T y i n f ot o n e i g h b o r s o f i t &

s e n d R R E P t o n e x t h o s t

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Example

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