Quality-of-Service

in

IP

Services

over

Bluetooth

Ad-Hoc

Networks

Along

with

the

development

of

multimedia

and

wireless

networking

technologies

mobile

multimedia

applications

are

playing

more

important

roles

in

information

access

Quality

of

Service

-LRB-

QoS

-RRB-

is

a

critical

issue

in

providing

guaranteed

service

in

a

low

bandwidth

wireless

environment

To

provide

Bluetooth-IP

services

with

differentiated

quality

requirements

a

QoS-centric

cascading

mechanism

is

proposed

in

this

paper

This

innovative

mechanism

composed

of

intra-piconet

resource

allocation

inter-piconet

handoff

and

Bluetooth-IP

access

modules

is

based

on

the

Bluetooth

Network

Encapsulation

Protocol

-LRB-

BNEP

-RRB-

operation

scenario

From

our

simulations

the

handoff

connection

time

for

a

Bluetooth

device

is

up

to

s

and

the

maximum

average

transmission

delay

is

up

to

s

when

seven

devices

join

a

piconet

simultaneously

Increasing

the

queue

length

for

the

Bluetooth-IP

access

system

will

decrease

the

traffic

loss

rate

by

per

IP

packets

at

the

expense

of

a

small

delay

performance

Wireless

communications

have

evolved

rapidly

over

the

past

few

years

Much

attention

has

been

given

to

research

and

development

in

wireless

networking

and

personal

mobile

computing

-LSB-

-RSB-

The

number

of

computing

and

telecommunications

devices

is

increasing

and

consequently

portable

computing

and

communications

devices

like

cellular

phones

personal

digital

assistants

tablet

PCs

and

home

appliances

are

used

widely

Wireless

communication

technologies

will

offer

the

subscriber

greater

flexibility

and

capability

than

ever

before

-LSB-

-RSB-

In

February

mobile

telephony

and

computing

leaders

Ericsson

Nokia

IBM

Toshiba

and

Intel

formed

a

Special

Interest

Group

-LRB-

SIG

-RRB-

to

create

a

standard

radio

interface

named

Bluetooth

-LSB-

-RSB-

The

main

aim

of

Bluetooth

has

been

the

development

of

a

wireless

replacement

for

cables

between

electronic

devices

via

a

universal

radio

link

in

the

globally

available

and

unlicensed

GHz

Industrial

Scientific

and

Medical

-LRB-

ISM

-RRB-

frequency

band

-LSB-

-RSB-

Bluetooth

technologies

have

the

potential

to

ensure

that

the

best

services

system

resources

and

quality

are

delivered

and

used

efficiently

However

global

services

will

embrace

all

types

of

networks

Therefore

bluetooth-based

service

networks

will

interconnect

with

existing

networks

to

provide

wide

area

network

connectivity

and

Internet

access

to

and

between

individuals

and

devices

-LSB-

-RSB-

In

Reference

-LSB-

-RSB-

the

BLUEPAC

-LRB-

BLUEtooth

Public

ACcess

-RRB-

concepts

presented

ideas

for

enabling

mobile

Bluetooth

devices

to

access

local

area

networks

in

public

areas

such

as

airports

train

stations

and

supermarkets

The

Bluetooth

specification

defined

how

Bluetooth-enabled

devices

-LRB-

BT

-RRB-

can

access

IP

network

services

using

the

IETF

Point-to-Point

Protocol

-LRB-

PPP

-RRB-

and

the

Bluetooth

Network

Encapsulation

Protocol

-LRB-

BNEP

-RRB-

-LSB-

-RSB-

By

mapping

IP

addresses

on

the

corresponding

BT

addresses

-LRB-

-RRB-

common

access

across

networks

is

enabled

-LSB-

-RSB-

This

means

that

devices

from

different

networks

are

allowed

to

discover

and

use

one

another

's

services

without

the

need

for

service

translation

or

user

interaction

To

support

communications

between

all

Bluetooth-based

home

appliances

and

the

existing

IP

world

over

Bluetooth

-LRB-

-RRB-

technology

was

proposed

-LSB-

-RSB-

The

technology

suggested

that

no

additional

link

layer

or

encapsulation

protocol

headers

be

used

However

the

development

of

technology

is

still

in

progress

The

BNEP

protocol

was

referred

to

as

the

key

technology

in

our

research

What

with

the

development

of

applications

and

wireless

networking

technologies

mobile

multimedia

applications

are

playing

more

important

roles

in

information

access

-LSB-

-RSB-

To

provide

responsive

multimedia

services

-LRB-

high

QoS

-RRB-

in

a

Bluetooth-IP

mobile

environment

a

pre-requisite

for

our

discussion

is

seamless

data

transmission

A

cascading

system

with

fair

resource

allocation

scheme

seamless

handoff

strategy

and

transparent

bridging

system

that

provides

a

way

of

integrating

IP

networks

and

Bluetooth-based

service

networks

to

relay

multimedia

applications

within

residual

and

enterprise

is

thus

inevitable

-LSB-

-RSB-

The

rest

of

this

paper

is

organized

as

follows

The

following

section

describes

Bluetooth

background

information

including

the

piconet

scatternet

IP

over

Bluetooth

service

architecture

Section

presents

the

proposed

QoS-centric

cascading

mechanism

including

the

intra-piconet

resource

allocation

inter-piconet

handoff

and

Bluetooth-IP

access

system

The

simulation

model

and

performance

analysis

of

the

W.-C

CHAN

ET

AL.

queue

length

loss

rate

average

delay

are

introduced

in

section

Section

presents

our

concluding

remarks

Figure

is

a

Bluetooth-IP

service

network

environment

When

a

BT

user

wants

to

receive

a

networked

video

stored

on

a

remote

video

server

the

BT

-LRB-

maybe

a

slave

in

a

picocell

-RRB-

will

initiate

a

connection

procedure

with

the

picocell

master

The

master

initiates

a

connection

procedure

with

the

video

server

through

the

Bluetooth-IP

access

system

During

the

connection

state

the

video

stream

will

be

fed

through

the

access

system

master

to

BT

user

-LRB-

the

dotted

line

of

figure

-RRB-

Piconet

When

two

BTs

establish

a

connection

one

BT

will

act

as

master

and

the

other

as

the

slave

More

BTs

can

join

the

piconet

A

single

piconet

can

accommodate

up

to

seven

active

slaves

If

a

slave

does

not

need

to

participate

in

the

channel

it

should

still

be

frequency-hop

synchronized

and

switch

to

a

low-power

Park

mode

The

master

can

also

request

that

the

slave

enter

the

Park

mode

so

the

master

can

communicate

more

than

seven

slave

BTs

The

master

determines

the

frequency-hop

sequence

the

timing

and

the

scheduling

of

all

packets

in

the

piconet

Within

a

piconet

the

master

initiates

the

connection

procedure

although

the

application

may

necessitate

that

the

master

and

slave

roles

be

exchanged

For

instance

such

an

exchange

is

necessary

when

a

BT

receives

network

services

through

Bluetooth-IP

access

systems

In

this

circumstance

the

access

system

provides

an

IP

service

that

may

be

used

by

many

other

BTs

This

situation

requires

that

the

access

system

be

the

master

of

the

piconet

and

the

other

BTs

to

act

as

slaves

However

when

the

device

is

initially

activated

and

looks

for

an

access

system

it

may

be

the

device

initiating

the

connection

This

will

make

the

device

the

master

and

the

access

system

the

slave

-LSB-

-RSB-

Scatternet

Several

piconets

can

be

established

and

linked

together

to

form

an

ad-hoc

network

This

is

called

a

scatternet

A

BT

can

participate

in

two

or

more

overlaying

piconets

by

applying

time

multiplexing

To

participate

on

the

proper

channel

the

BT

should

use

the

associated

master

device

address

and

proper

clock

offset

to

obtain

the

correct

phase

A

BT

can

act

as

a

slave

in

several

piconets

but

only

as

a

master

in

a

sin-Figure

Bluetooth-IP

service

network

environment

QUALITY-OF-SERVICE

IN

IP

SERVICES

Figure

An

inter-piconet

node

in

the

scatternet

gle

piconet

because

two

piconets

with

the

same

master

are

synchronous

and

use

the

same

hopping

sequence

This

syn-chronization

makes

them

one

and

the

same

piconet

Time

multiplexing

must

be

used

to

switch

between

piconets

In

figure

an

inter-piconet

node

is

capable

of

time-sharing

between

multiple

piconets

This

allows

the

traffic

to

flow

within

and

between

the

piconets

-LSB-

-RSB-

In

the

case

of

data

links

only

a

BT

can

request

to

enter

the

Hold

or

Park

mode

in

the

current

piconet

during

which

time

it

may

join

another

piconet

by

just

changing

the

channel

parameters

BTs

in

the

Sniff

mode

may

have

sufficient

time

to

visit

another

piconet

in

between

the

Sniff

slots

If

audio

links

are

established

other

piconets

can

only

be

visited

in

the

non-reserved

slots

IP

networking

The

LAN

Access

profile

defines

IP

service

access

using

PPP

over

RFCOMM

TCP/IP

runs

on

the

PPP

protocol

BTs

can

receive

IP

services

using

the

PPP

protocol

-LSB-

-RSB-

When

a

BT

wants

to

receive

IP

service

it

will

find

a

LAN

Access

Point

-LRB-

LAP

-RRB-

within

radio

range

through

inquiry

and

paging

After

the

data

links

have

been

setup

the

LMP

-LRB-

Protocol

-RRB-

will

process

the

master/slave

switch

and

the

connection

will

then

be

established

A

suitable

IP

address

is

negotiated

between

devices

in

the

PPP

layer

The

BT

can

forward

IP

packets

through

the

LAP

Encapsulating

an

Ethernet

packet

inside

a

PPP

packet

is

not

an

efficient

solution

Moreover

PPP

is

not

sufficient

for

ad-hoc

networks

that

contain

multiple

wireless

hops

The

best

way

of

providing

networking

would

be

to

Ethernet

over

the

layer

The

Bluetooth

Network

Encapsulation

Protocol

-LRB-

BNEP

-RRB-

was

pursued

by

the

Bluetooth

SIG

PAN

working

group

to

provide

an

Ethernet-like

interface

to

IP

services

-LSB-

-RSB-

as

depicted

in

figure

From

figure

a

BT

that

accesses

multimedia

services

on

the

Internet

may

do

so

through

a

piconet

or

scatternet

QoS

is

critical

in

transmitting

of

different

network

segments

To

provide

Bluetooth-IP

services

with

differentiated

quality

requirements

a

QoS-centric

cascading

mechanism

is

proposed

Figure

BNEP

protocol

stack

Figure

The

proposed

QoS-centric

cascading

modules

in

our

research

to

tunnel

the

guaranteed

applications

The

operational

modules

are

illustrated

in

figure

The

innovative

mechanism

consists

of

three

modules

intra-piconet

resource

allocation

inter-piconet

handoff

and

Bluetooth-IP

access

system

These

modules

were

developed

based

on

the

BNEP

operation

scenarios

Intra-piconet

resource

allocation

Two

service

types

Synchronous

Connection

Oriented

-LRB-

SCO

-RRB-

and

Asynchronous

Connectionless

Link

-LRB-

ACL

-RRB-

were

defined

in

the

Bluetooth

service

environment

Through

the

QoS

setup

the

ACL

link

can

be

configured

to

provide

QoS

requirements

The

ACL

link

can

be

configured

with

the

Flush

Timeout

setting

which

prevents

re-transmission

when

it

is

no

longer

useful

Acknowledgement

can

be

received

within

ms.

This

makes

the

delay

small

and

it

is

possible

to

perform

re-transmission

for

real-time

applications

The

ACL

link

also

supports

variable

and

asymmetrical

bandwidth

requirement

applications

Currently

the

IP

QoS

architecture

is

based

purely

on

IP-layer

decision

making

packet

buffering

and

scheduling

through

a

single

link-layer

service

access

point

The

mechanism

in

the

link

layer

has

better

understanding

of

the

communications

medium

status

However

simplicity

has

been

important

design

objective

for

the

Bluetooth

interface

and

the

number

of

IP-based

protocols

is

becoming

increasingly

more

complex

As

depicted

in

figure

QoS

architecture

at

the

network

layer

such

as

differentiated

and

integrated

services

provides

different

services

to

applications

These

services

at

W.-C

CHAN

ET

AL.

Figure

Bluetooth

IP

QoS

mechanism

Figure

General

QoS

framework

the

high

layer

are

sufficient

depending

on

the

particular

scenario

With

shared

bandwidth

and

a

re-transmission

scheme

the

Host

Controller

-LRB-

HC

-RRB-

buffering

will

invoke

delays

The

HC

buffer

size

can

be

decreased

to

reduce

the

buffer

delay

In

bluetooth-based

service

layer

the

layer

informs

the

remote

side

of

the

non-default

parameters

and

sends

a

Configuration

Request

The

remote

responds

to

the

Configuration

Response

that

agrees

or

disagrees

with

these

requirements

If

the

Configuration

Response

disagrees

the

local

side

sends

other

parameters

to

re-negotiate

or

stop

the

connection

The

Link

Manager

uses

the

poll

interval

and

repetitions

for

broadcast

packets

to

support

QoS

The

poll

interval

which

is

defined

as

the

maximum

time

between

subsequent

transmissions

from

the

master

to

a

particular

slave

on

the

ACL

link

is

used

to

support

bandwidth

allocation

and

latency

control

Figure

depicts

the

general

framework

which

defines

the

basic

functions

required

to

support

QoS

In

figure

the

traffic

and

QoS

requirements

for

the

QoS

flow

from

the

high

layer

sends

the

request

to

the

Resource

Requester

-LRB-

RR

-RRB-

Based

on

this

request

the

RR

generates

a

resource

request

to

the

Resource

Manager

-LRB-

RM

-RRB-

When

the

RM

accepts

the

request

the

RR

configures

parameters

to

the

local

Resource

Allocation

-LRB-

RA

-RRB-

entity

The

RA

actually

reserves

resources

to

satisfy

the

QoS

requirements

The

QoS

is

satisfied

by

the

application

that

receives

the

appropriate

resource

In

our

scheme

bluetooth-based

operation

identifies

the

following

functions

and

procedures

to

determine

the

amount

of

resources

assigned

to

a

traffic

flow

A

polling

algorithm

determines

which

slave

is

polled

next

and

bandwidth

is

assigned

to

that

slave

The

slave

uses

the

air-interface

scheduler

to

determine

which

data

to

send

when

it

is

polled

An

inter-piconet

scheduling

algorithm

is

used

by

the

inter-piconet

node

to

efficiently

control

the

traffic

flow

between

two

piconets

Bluetooth

also

uses

the

Flush

Timeout

setting

to

determine

the

maximum

delay

involved

with

re-transmissions

The

Link

Manager

module

in

the

master

selects

the

baseband

packet

type

for

transmission

in

the

single

three

and

five

time

slots

-LSB-

-RSB-

Inter-piconet

handoff

The

inter-piconet

environment

suffers

many

challenges

First

the

formation

of

Bluetooth

networks

is

spontaneous

and

the

problem

of

scatternet

formation

has

not

been

defined

in

the

Bluetooth

specification

-LSB-

-RSB-

Some

researches

have

addressed

these

issues

in

the

formation

of

an

efficient

scatternet

-LSB-

-RSB-

The

data

sent

forward

between

nodes

must

been

sent

via

the

master

Sometimes

this

data

will

traffic

through

multiple

hops

in

the

scatternet

Efficient

routing

protocols

are

needed

for

Bluetooth

The

inter-piconet

node

as

the

bridge

over

which

a

piconet

controls

communications

between

piconets

Smarter

traffic

control

is

needed

to

coordinate

with

these

masters

Different

data

rates

exist

in

each

link

in

different

scenarios

The

inter-piconet

node

becomes

the

bottleneck

for

the

scatternet

In

a

piconet

the

master

controls

all

of

the

slaves

in

the

piconet

The

inter-piconet

node

joins

more

than

two

piconets

but

it

is

only

active

in

one

piconet

at

a

time

To

efficiently

move

traffic

between

different

piconets

scheduling

is

needed

to

coordinate

the

inter-piconet

and

the

master

In

Reference

-LSB-

-RSB-

inter-piconet

-LRB-

IPS

-RRB-

and

intra-piconet

scheduling

-LRB-

IPRS

-RRB-

were

presented

to

interact

with

one

another

to

provide

an

efficient

scatternet

scheduler

as

illustrated

in

figure

The

IPS

and

IPRS

must

coordinate

with

one

another

to

schedule

when

the

inter-piconet

node

belongs

to

which

piconet

and

how

and

when

to

transfer

data

packets

between

the

different

masters

Bluetooth

connection

progress

includes

two

steps

the

inquiry

progress

and

the

paging

progress

This

causes

the

bottleneck

in

the

handoff

Two

situations

were

discussed

in

BLUEPAC

When

the

Access

Point

is

the

master

the

mobile

node

joins

the

piconet

as

a

slave

The

Access

Point

can

efficiently

control

the

traffic

to

the

Internet

However

the

disadvantage

is

that

the

Access

Point

must

periodically

enter

the

inquiry

stage

to

find

the

newly

arrived

mobile

node

This

will

interrupt

the

Access

Point

transfer

a

packet

to

the

Internet

In

a

situation

in

which

the

BT

is

the

master

the

Access

Point

involves

itself

in

multiple

piconets

The

BT

can

actively

inquire

the

Access

Point

when

it

wants

to

connect

to

the

Access

Point

However

the

traffic

control

becomes

difficult

and

complex

when

the

Access

Point

must

switch

between

various

piconets

The

scheduler

is

still

not

supported

for

seamless

handoffs

in

real

time

applications

To

solve

this

problem

reference

-LSB-

-RSB-

proposes

the

Next

Hop

Handoff

Protocol

-LRB-

NHHP

-RRB-

to

support

fast

handoffs

The

major

focus

is

on

reducing

the

connection

time

in

the

strategy

A

scheme

that

passes

the

inquiry

information

to

the

next

Access

Point

was

used

to

avoid

wasting

time

in

the

inquiry

stage

The

disadvantage

is

that

the

Access

Points

are

divided

into

two

categories

Entry

Points

QUALITY-OF-SERVICE

IN

IP

SERVICES

which

constantly

make

inquiries

to

the

new

BT

and

pass

information

to

the

Access

Points

in

the

internal

regions

have

the

responsibility

in

the

handoff

If

a

newly

arrived

BT

is

initiated

in

an

internal

region

the

scheme

does

n't

work

To

resolve

the

above

problem

a

fast

handoff

scheme

was

proposed

This

scheme

assumes

Bluetooth

service

environment

is

a

micro-cellular

network

architecture

However

it

also

adapts

Bluetooth

as

a

macro-cellular

network

Based

on

the

fast

handoff

mission

the

major

focus

is

reducing

the

connection

procedure

that

causes

significant

delay

We

assumed

the

following

conditions

the

Access

Point

and

mobile

BT

periodically

scan

for

page

attempts

and

inquiry

requests

To

obtain

seamless

and

efficient

handoff

support

the

Access

Point

RF

range

should

cover

the

nearby

Access

Point

The

neighborhood

set

records

all

Access

Point

locations

Connection

procedure

As

depicted

in

figure

when

the

mobile

BT

accesses

the

Internet

it

initiates

an

inquiry

to

the

Access

Point

and

makes

a

connection

The

Access

Point

passes

the

BT

addresses

and

clock

information

to

the

nearest

Access

Point

according

to

the

neighborhood

set

The

nearest

Access

Point

uses

this

information

to

page

the

BT

and

form

the

piconets

These

piconets

form

the

scatternet

and

the

BT

becomes

the

inter-piconet

node

between

them

The

BT

depends

on

the

received

signal

strength

indicator

-LRB-

RSSI

-RRB-

to

determine

which

Access

Point

to

use

to

access

the

Internet

The

BT

is

a

dedicated

Access

Point

only

in

the

connection

state

The

remaining

piconets

are

all

in

the

Hold

state

Handoff

The

BT

periodically

monitors

the

RSSI

and

bit

error

rate

When

the

RSSI

decreases

to

the

lower

threshold

a

handoff

may

take

place

To

know

where

the

mobile

BT

moves

the

BT

detects

which

RSSI

becomes

stronger

It

then

informs

the

Access

Points

and

Foreign

Agent

that

a

handoff

is

imminent

-LRB-

figure

-LRB-

A

-RRB-

-RRB-

The

BT

leaves

the

Hold

state

to

the

connection

state

in

the

piconet

that

contains

the

coming

Access

Point

-LRB-

in

figure

-LRB-

B

-RRB-

-RRB-

The

routing

path

also

changes

to

a

new

path

Additional

caches

may

be

needed

in

the

Access

Point

to

avoid

packet

losses

The

new

nearest

Access

Point

-LRB-

APa

in

figure

-LRB-

C

-RRB-

-RRB-

in

accordance

with

the

neighbor

set

is

notified

that

the

mobile

BT

is

within

range

to

receive

BT

information

It

begins

to

page

the

BT

and

enter

the

Hold

state

with

the

BT

The

original

connection

state

also

turns

into

the

Hold

state

in

the

piconet

that

contains

the

original

access

-LRB-

in

figure

-LRB-

D

-RRB-

-RRB-

When

the

BT

does

not

seek

access

service

from

the

Access

Point

it

should

inform

the

Access

Point

that

it

no

longer

wants

a

connection

A

connection

could

break

down

without

prior

warning

In

the

Bluetooth

specification

both

the

master

and

slave

use

the

link

supervision

time

to

supervise

the

loss

The

supervision

timeout

period

is

chosen

so

that

the

value

is

longer

than

the

hold

periods

For

simplicity

of

discussion

we

assumed

that

the

Bluetooth

AP

is

the

application

sender

and

divided

the

architecture

into

two

parts

wired

parts

the

correspondent

node

-LRB-

CN

-RRB-

to

the

Bluetooth

AP

and

wireless

part

the

Bluetooth

AP

to

the

mobile

BT

device

The

wired

part

is

the

same

as

the

current

general

mechanism

We

will

only

discuss

the

mechanism

that

combines

the

wireless

part

and

our

handoff

mechanism

in

the

Bluetooth

environment

After

making

a

connection

and

switching

roles

as

mentioned

earlier

the

Bluetooth

AP

becomes

a

master

As

illustrated

in

figure

the

Bluetooth

sends

an

active

PATH

message

to

the

BT

in

figure

-LRB-

-RRB-

After

the

BT

receives

the

PATH

message

if

the

BT

needs

RSVP

Figure

Connection

procedures

W.-C

CHAN

ET

AL.

Figure

Handoff

procedures

Figure

RSVP

messages

for

bluetooth

resource

reservation

support

it

sends

a

resource

reservation

request

with

a

RESV

message

to

the

in

figure

-LRB-

-RRB-

When

the

traffic

specification

contains

a

RSVP

message

the

traffic

and

QoS

requirements

for

the

QoS

flow

from

the

high

layer

sends

a

request

to

the

Resource

Requester

-LRB-

RR

-RRB-

The

Bluetooth

low

levels

will

thus

coordinate

with

one

another

Once

the

Bluetooth

accepts

the

request

the

reservation

along

the

flow

between

the

and

BT

is

made

After

this

point

the

Bluetooth

must

have

reservations

in

the

neighboring

APs

The

resource

reservation

request

is

the

same

as

an

active

reservation

The

current

sends

a

Passive

PATH

message

to

the

neighboring

The

responds

with

a

Passive

RESV

message

and

reserves

the

resources

that

the

BT

may

need

Because

Bluetooth

can

have

only

seven

active

slaves

in

a

piconet

at

the

same

time

the

resources

must

be

used

efficiently

One

way

is

adding

more

Bluetooth

devices

in

an

AP

This

can

be

easily

achieved

by

modifying

the

application

layer

As

discussed

before

to

support

seamless

handoffs

information

about

the

BT

is

sent

to

the

after

the

RSVP

process

is

performed

The

Hold

state

is

maintained

between

the

BT

and

However

if

the

BT

does

not

need

a

QoS

guarantee

Figure

The

protocol

stack

for

Bluetooth-IP

interworking

the

QoS

mechanism

is

not

added

After

supporting

the

end-to

end

QoS

using

the

RSVP

protocol

the

packet

classification

and

scheduler

can

be

used

to

control

the

traffic

Bluetooth-IP

access

system

Th

difference

between

existing

Bluetooth

piconets

and

IP

LANs

is

the

communication

protocol

stack

illustrated

in

figure

From

figure

these

differences

are

shown

in

the

lower

OSI

seven

layers

The

lower

layers

are

responsible

for

connection

and

addressing

We

therefore

focused

on

the

connection

management

and

address

resolution

issues

in

our

research

The

access

function

allows

connections

to

be

established

without

requiring

any

particular

knowledge

or

interaction

The

Bluetooth-IP

access

system

plays

the

role

of

bridg-ing/routing

multimedia

traffic

between

the

various

LANs

and

piconets

Their

operational

scenario

is

illustrated

in

figure

When

different

piconet

devices

are

connected

directly

to

the

access

system

the

access

system

function

is

referred

to

as

a

bridge

-LRB-

piconet

Master

and

Slave

role

-RRB-

If

a

LAN

host

-LRB-

piconet

BT

-RRB-

communicates

with

a

piconet

BT

-LRB-

LAN

host

-RRB-

through

the

access

system

because

of

the

different

protocol

stacks

between

the

piconet

and

LAN

networks

two

issues

addressing

and

connection

must

be

resolved

in

the

design

QUALITY-OF-SERVICE

IN

IP

SERVICES

Figure

Bluetooth-IP

interworking

operational

scenario

Address

resolution

To

achieve

the

interconnection

function

in

a

Bluetooth-IP

environment

the

access

system

must

refer

to

both

the

piconet

and

LAN

networks

as

members

Thus

two

different

protocol

stacks

must

be

combined

to

form

a

new

communication

protocol

stack

suitable

as

a

routing

server

The

combined

protocol

stack

is

shown

in

figure

Using

the

protocol

stack

specifications

a

scenario

for

addressing

is

identified

as

follows

Step

Each

LAN

host

assigns

an

IP

address

Each

host

thus

possesses

two

addresses

an

IP

address

and

a

MAC

address

Step

Each

piconet

BT

acquires

two

addresses

a

BT

address

-LRB-

-RRB-

and

an

IP

address

Step

A

routing

table

must

be

built

for

interconnection

in

the

access

system

A

lookup

for

destination

addresses

is

needed

to

find

the

corresponding

outbound

or

MAC

address

to

which

the

packet

must

be

forwarded

Connection

management

Because

the

existing

LAN

is

a

packet

switching

service

and

BT

connections

are

made

on

an

ad

hoc

basis

interconnection

is

very

difficult

To

solve

this

problem

a

mechanism

based

on

IP

services

over

Bluetooth

was

proposed

in

the

Bluetooth

specification

The

system

is

as

follows

Step

Bluetooth

adapters

and

an

Ethernet

card

are

embed-ded

into

a

desktop

computer

These

adapters

and

card

are

referred

to

as

network

attachment

units

-LRB-

wired

or

Figure

The

Bluetooth-IP

access

system

radio

-RRB-

Each

port

in

the

interface

is

directly

attached

to

different

networks

-LRB-

see

figure

-RRB-

Step

The

API

of

the

Bluetooth

adapter

and

the

Ethernet

packet

driver

are

used

to

design

an

access

system

The

operational

procedures

for

this

system

follow

the

scenario

in

figure

The

Bluehoc

toolkit

was

used

to

simulate

the

various

scenarios

in

the

Bluetooth-IP

service

environment

As

depicted

in

figure

the

data

is

dumped

from

the

W.-C

CHAN

ET

AL.

Figure

packet

flow

and

into

the

connection

state

The

and

events

are

the

upper-Layer

to

the

events

The

is

the

event

that

requests

transfer

for

received

data

from

the

entity

to

the

upper

layer

The

is

the

event

that

requests

data

transfer

from

the

upper

layer

to

the

entity

for

transmission

over

an

open

channel

In

the

Bluehoc

toolkit

the

connection

procedures

such

as

inquiry

and

paging

are

simulated

according

to

the

Bluetooth

specifications

The

master

sends

the

QoS

parameters

which

depend

on

the

application

QoS

parameters

are

then

passed

to

the

Deficit

Round

Robin

-LRB-

DRR

-RRB-

based

scheduler

that

determines

if

the

connection

can

be

accepted

by

the

LMP

The

DRR-based

scheduler

finds

the

appropriate

ACL

link

baseband

packet

type

-LRB-

and

-RRB-

depending

upon

the

application

level

MTU

and

loss

sensitivity

The

simulation

applications

include

packetized

voice

Telnet

and

FTP

Simulation

results

In

figure

the

average

delay

for

various

numbers

of

slaves

using

packetized

voice

in

a

piconet

is

shown

The

voice

application

is

real

time

and

would

be

sensitive

to

a

loss

of

several

consecutive

small

packets

Figure

shows

the

average

delay

in

the

mixed

traffic

source

The

short-packet

delay

such

as

telnet

applications

are

significantly

increased

by

the

long-packet

in

the

DRR-based

scheduler

An

efficient

and

simple

scheme

that

does

not

add

to

the

Bluetooth

load

is

important

Queue

length

analysis

The

queue

length

analysis

was

based

on

the

access

system

queue

size

We

observed

the

variations

in

queue

length

using

specified

traffic

levels

In

figure

the

queue

length

of

the

traffic

from

M

LAN

to

M

piconet

increases

very

fast

It

reaches

packets

within

s

The

queue

length

for

the

traffic

from

M

LAN

to

M

piconet

increases

more

smoothly

and

the

queue

length

of

the

traffic

from

M

piconet

to

M

or

M

LANs

is

almost

zero

Figure

Average

delay

with

voice

services

Figure

Average

delay

in

the

mixed

traffic

Figure

Queue

length

analysis

Loss

rate

analysis

In

the

loss

rate

analysis

the

queue

length

was

changed

to

observe

the

variations

in

the

loss

rate

In

figure

when

the

queue

length

is

smaller

than

packets

the

loss

rate

is

close

to

When

the

queue

length

increases

to

packets

the

loss

rate

decreases

to

Therefore

increasing

the

queue

length

will

decrease

the

traffic

loss

rate

The

loss

rate

from

LAN

to

M

piconet

is

a

little

more

than

that

for

M

LAN

to

M

piconet

because

of

the

difference

in

the

LAN

transport

speed

QUALITY-OF-SERVICE

IN

IP

SERVICES

Figure

Loss

rate

analysis

Figure

Throughput

analysis

Throughput

analysis

From

figure

increasing

the

queue

length

has

no

effect

on

improving

the

throughput

The

throughput

is

smooth

in

both

the

LAN

to

piconet

and

piconet

to

LAN

traffic

Delay

analysis

From

figure

when

the

queue

length

is

packets

the

delay

is

about

seconds

per

bit

If

the

queue

length

increases

to

packets

the

delay

becomes

almost

double

When

the

queue

length

reaches

packets

the

delay

is

close

to

seconds

per

bit

The

transfer

delay

has

no

obvious

change

when

the

queue

length

increases

to

packets

In

a

wireless

environment

the

QoS

guarantee

provision

becomes

more

important

The

frequent

mobility

of

a

host

increases

the

service

disruption

in

real-time

applications

Even

though

efficient

RSVP

enhances

the

resource

reservation

ability

and

allows

for

requesting

a

specific

QoS

from

the

network

these

mechanisms

do

not

have

enough

QoS

guarantee

to

prevent

service

disruption

during

handoff

In

this

paper

a

cascading

mechanism

for

QoS

guarantee

in

a

Bluetooth-IP

environment

was

proposed

A

fast

and

efficient

handoff

scheme

that

supports

BT

roaming

handoffs

between

different

Access

Points

was

proposed

Concepts

for

the

mobile

RSVP

issues

in

Bluetooth

networks

were

presented

with

our

fast

handoff

mechanism

The

Bluetooth-IP

access

system

can

be

implemented

using

available

technology

such

as

Network

Addressing

Translation

-LRB-

NAT

-RRB-

and

Linux

Bluetooth

Stack

to

connect

Bluetooth

piconets

and

LAN

In

our

simulations

Bluetooth

required

a

long

time

to

process

the

inquiry

and

paging

procedures

These

results

show

that

the

connection

time

is

up

to

sec

when

seven

slaves

join

a

piconet

at

the

same

time

Moreover

the

access

system

queue

length

increases

by

about

packets

per

second

in

a

Mbps

LAN

and

about

packets

per

second

in

a

Mbps

LAN

when

the

traffic

load

is

In

the

loss

rate

analysis

the

loss

rate

was

close

to

when

the

queue

length

was

less

than

packets

However

when

the

queue

length

increased

to

packets

the

W.-C

CHAN

ET

AL.

Figure

Delay

analysis

loss

rate

decreased

to

In

the

delay

analysis

the

delay

was

about

seconds

per

bit

when

the

queue

length

was

packets

The

delay

doubles

when

the

queue

length

doubles

However

when

the

queue

length

is

more

than

packets

the

delay

has

no

obvious

variance

This

paper

is

a

partial

result

of

project

no

conducted

by

National

Dong

Hwa

University

under

the

sponsorship

of

National

Science

Council

ROC

-LSB-

-RSB-

M.

Albrecht

M.

Frank

P.

Martini

M.

Schetelig

A.

Vilavaara

and

A.

Wenzel

IP

service

over

bluetooth

Leading

the

way

to

a

new

mobility

in

Proceedings

of

the

International

Conference

on

Local

Computer

Networks

-LRB-

-RRB-

pp.

-LSB-

-RSB-

S.

Baatz

M.

Frank

R.

Gopffarth

D.

Kassatkine

P.

Martini

M.

Schetelig

and

A.

Vilavaara

Handoff

support

for

mobility

with

IP

over

bluetooth

in

Proceedings

of

the

Annual

IEEE

Conference

on

Local

Computer

Networks

USA

-LRB-

-RRB-

pp.

-LSB-

-RSB-

J.L.

Chen

and

K.C.

Yen

Transparent

bridging

support

for

bluetooth-IP

service

interworking

International

Journal

of

Network

Management

-LRB-

-RRB-

-LSB-

-RSB-

J.L.

Chen

A.P.

Shu

H.W.

Tzeng

and

P.T.

Lin

Fair

scheduling

for

guaranteed

services

on

personal

area

networks

in

Proceedings

of

International

Conference

on

Communications

Circuits

and

Systems

China

-LRB-

-RRB-

pp.

-LSB-

-RSB-

L.

Ching

and

K.Y.

Siu

A

bluetooth

scatternet

formation

algorithm

in

Proceedings

of

IEEE

Global

Telecommunications

Conference

Vol

-LRB-

-RRB-

pp.

-LSB-

-RSB-

A.

Das

A.

Ghose

A.

Razdan

H.

Saran

and

R.

Shorey

Enhancing

performance

of

asynchronous

data

traffic

over

the

bluetooth

wireless

ad-hoc

network

in

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of

the

IEEE

INFOCOM

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pp.

-LSB-

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D.

Famolari

and

P.

Agrawal

Architecture

and

performance

of

an

em-bedded

IP

bluetooth

personal

area

network

in

Proceedings

of

the

International

Conference

on

Personal

Wireless

Communications

India

-LRB-

-RRB-

pp.

-LSB-

-RSB-

M.

Frank

R.

Goepffarth

W.

Hansmann

and

U.

Mueller

Transmission

of

native

over

bluetooth

-LSB-

-RSB-

C.

Haartsen

and

S.

Mattisson

Bluetooth

a

new

low-power

radio

interface

providing

short-range

connectivity

Proceedings

of

the

IEEE

-LRB-

-RRB-

-LRB-

-RRB-

-LSB-

-RSB-

G.

Ivano

D.

Paolo

and

F.

Paolo

The

role

of

Internet

technology

in

future

mobile

data

systems

IEEE

Communications

Magazine

-LRB-

-RRB-

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-LSB-

-RSB-

P.

Johansson

R.

Kapoor

M.

Kazantzidis

and

M.

Gerla

Rendezvous

scheduling

in

bluetooth

scatternets

in

Proceedings

of

IEEE

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on

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Vol

-LRB-

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pp.

-LSB-

-RSB-

D.J.Y.

Lee

and

W.C.Y.

Lee

Ricocheting

bluetooth

in

Proceedings

of

the

International

Conference

on

Microwave

and

Millimeter

Wave

Technology

-LRB-

-RRB-

pp.

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D.G.

Leeper

A

long-term

view

of

short-range

wireless

IEEE

Computer

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Y.B.

Lin

and

I.

Chlamtac

Wireless

and

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Wiley

-RRB-

-LSB-

-RSB-

I.

Mahadevan

and

K.M.

Sivalingam

An

architecture

and

experimental

results

for

quality

if

service

in

mobile

networks

using

RSVP

and

CBQ

ACM/Baltzer

Wireless

Networks

Journal

-LRB-

-RRB-

-LRB-

-RRB-

-LSB-

-RSB-

B.

Raman

P.

Bhagwat

and

S.

Seshan

Arguments

for

cross-layer

opti-mizations

in

Bluetooth

scatternets

in

Proceedings

of

Symposium

on

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and

the

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pp.

-LSB-

-RSB-

T.S.

Rappaport

Wireless

Communications

Principles

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T.

Salonidis

P.

Bhagwat

L.

Tassiulas

and

R.

LaMaire

Distributed

topology

construction

of

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personal

area

networks

in

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of

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pp.

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The

Bluetooth

Special

Interest

Group

Bluetooth

Network

Encapsulation

Protocol

Specification

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-RSB-

The

Bluetooth

Special

Interest

Group

Documentation

available

at

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The

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Interest

Group

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of

service

in

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V.

Zaruba

S.

Basagni

and

I.

Chlamtac

Bluetrees-scatternet

formation

to

enable

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ad

hoc

networks

in

Proceedings

of

IEEE

International

Conference

on

Communications

Vol

-LRB-

-RRB-

pp.

QUALITY-OF-SERVICE

IN

IP

SERVICES

Wah-Chun

Chan

received

the

Ph.D.

degree

from

University

of

British

Columbia

in

He

is

cur-rently

a

Visiting

Professor

in

the

Department

of

Computer

Science

at

National

Chiao

Tung

University

Dr.

Chan

's

research

interest

has

been

in

the

areas

of

queueing

theory

and

telecommunication

networks

Research

on

telecommunication

networks

has

been

in

the

development

of

models

for

the

performance

analysis

of

computer

communication

networks

Jiann-Liang

Chen

received

the

Ph.D.

degree

in

electrical

engineering

from

National

Taiwan

University

Taipei

Taiwan

in

Since

August

he

has

been

with

the

Department

of

Computer

Science

and

Information

Engineering

of

National

Dong

Hwa

University

where

he

is

a

Professor

now

His

current

research

interests

are

directed

at

cellular

mobility

management

and

personal

communication

systems

O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O B O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O B O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O

quality of service
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