Wireless ATM 에서의 무선 액세스 기술

고려대학교 전기전자전파공학부 강 충 구

WIRELESS INFORMATION SYSTEM ENGINEERING LABORATORY

Presented at HSN ‘98

1998. 2. 13.

WISE LAB

Wireless ATM History

(1) Petition to reallocate a block of unused spectrum at 5.2GHz in US

- NII from Apple - SUPERNet from WINForum (“Shared Unlicensed Personal Radio Network”)

(2) NPRM (Notice of Proposed Rule Making) from FCC

• Wireless ATM Working Group in ATM Forum (1996/8)

• ETSI STC RES 10: HIPERLAN/1 => HIPERLAN/2 (5.2GHz, ATM-based)

• Frequency Characteristics at 5.2GHz- Fading rate is almost 120 times greater

High-Speed MultimediaApplication

Short Packet

1 2 3

• United States

WISE LAB

유럽의 무선 ATM 및 무선 광대역 서비스 관련 과제

과제명 시스템 개요 주파수 전송률 환경MBS

(RACE Project)3rd generation mobile

broadband communication system60 GHz 155 Mb/s Indoors/

OutdoorsMagicWAND

(AC085)Wireless ATM network

demonstrator (무선 ATM 기술)Demo: 5 GHz

Research: 17 GHzDemo:

24 Mb/sIndoors

MEDIAN(AC006)

Wireless broadband CPN/LAN(무선 ATM 기술; MBS project 의 연장) 60 GHz 155 Mb/s

Indoors

SAMBA(AC204)

Broadband cellular radio extension toB-ISDN

40 GHz 34 Mb/s Cellular(Mobile)

CRABS Cellular radio access for broadbandinteractive and multimedia services

42 GHz 2~4 Mb/s Cellular(Fixed)

AWACS(AC10230)

ATM wireless accesscommunication system

19 GHz 34 Mb/s Indoors/Outdoors

무선 ATM 기반의 무선 멀티미디어 시스템 개발 과제

과제명 개요 추진 기관 주파수 전송률 서비스 환경

SWANSeamless Wireless ATM

Network: end-to-end ATMtransport to mobile users

AT&TBell Lab. 2.4 GHz

625 Kb/s(1 MHz) Indoors

BAHAMA Broadband Ad-Hoc ATMArchitecture

AT&TBell Lab.

Free Space OpticalLink; 900 MHz

1 Gb/s (PBS-PBS);2 Mb/s (PBS-MT)

Indoors

AWAPrototype ATM Wireless

Access System NTT3~30 GHz

(TBD)80 Mb/s

(50 Mb/s oneway;Max 12 Mb/s per user)

Indoors/Outdoors

WATMnet Prototype Wireless ATMSystem

NECC&C

2.4 GHz Type I: 8 Mb/sType II: 25 Mb/s

Indoors/Outdoors

ORATM PrototypeRadio ATM System

OlivettiResearch Lab

2.4 GHz 6 Mb/s Inddors

N/A PrototypeWireless ATM LAN

일본 우정성CRL

60 GHz > 50 Mb/s Indoors

무선 ATM 프로토타입 시스팀 구현 사례

WISE LAB

Europe ERC ETSI RES10 (HIPERLAN)

UMTS Forum (SMG3/SMG5)

ACTS

.

.

.

.

International ITU-T&R (FPLMTS)

WARC

.

.

U.S.A. FCC WINForum (WINSpectrum/SUPERnet)

IEEE 802.11

.

.

.

Japan / Asia TTC MPT MMAC-PC

.

.

.

ATM Forum(W-ATM Working Group)

표준화 동향

- ACTS: Advanced Communications Technologies and Services- RES10: Radio Equipment and System 10- UMTS: Universal Mobile Telephone System- TTC: Telecommunications Technical Committee- MMAC-PC: Multimedia Mobile Access Communication - Promotion Council

WISE LAB

R4

End-user MobilitySupporting ATM NW

R4

AP AP

R6R7

R3R3

AP AP

R9R8

R10

R0

Network MobilitySupporting ATM NW

Mobile ATM NW

R1FixedATM NW

APR2

R12

R11

R4

AP

R5

F

R5

R5

R5

R13

R5

R5

R5

: Wireless

AP : Access Point

: ATM Switch

: End-user Mobility Supporting ATM Switch

: Network mobility Supporting ATM Switch

: Mobile ATM Switch

: Mobile ATM terminal

: Wireless ATM terminal

: Wireless Mobile ATM terminal

: Dual Mode terminal

: PCS terminal P

F : Ad Hoc Forwarding Terminal

: Ad Hoc Central Controller TerminalBSCIWF

: PCS Base Station Controller w/ ATM <-> PCS Interworking Function

BSIWF

: PCS Base Station w/ ATM <-> PCS Interworking Function

R14

R15

R16* R16* P

BSCIWF

BSIWF BS

R17*

Reference Architecture - Application Scenario

WISE LAB

Wireless Access Layers for W-ATM

• 유선 ATM 망에서의 다중화 형태

SAALQ.2931

PHY

M-Ctrl

W-LLC

User Service

AAL SAAL

ATM

PHY

Q.2931

W-PHYPHY

W-LLCW-MAC

M-Ctrl

ATM

User Service

AAL SAAL

ATM

PHY

Q.2931

W-PHYPHY

W-LLCW-MAC

M-Ctrl

ATM

User Service

AAL SAAL

ATM

PHY

Q.2931

W-PHYPHY

W-LLCW-MAC

M-Ctrl

ATM

W-MACW-PHY

ATM

Base station

Wireless ATM terminal

ATM multiplexer

User Service

AAL SAAL

ATM

PHY

Q.2931

User Service

AAL SAAL

ATM

PHY

Q.2931

User Service

AAL SAAL

ATM

PHY

Q.2931

ATM

PHY PHYPHYPHY

ATM multiplexerATM terminal

• 무선 ATM 망에서의 다중화 형태

(1) Mobile = Distributed Queue(2) Channel = Unreliable Bit Pipe

WISE LAB

W-ATM Access Architecture (1)

Figure 1: WATM Access Architecture

EMAS-E

EMAS-N

EMAS-N

NNI+M

NNI+M

MT

Modular Access

APRP

AP

APCP

APCP

EMAS-E

EMAS-N

EMAS-N

NNI+M

NNI+M

MT

RP

Integrated Access

EMAS-E

NNI+M

• Integrated Access vs. Modular Access

- Integrated Access: No AP involved- Modular Access: AP as virtual multiplexer

APCP: Access Point Control Protocol

MT: Mobile TerminalRP: Radio PortAP: Access PointEMAS: End-user Mobility supporting ATM switch - EMAS-E: Entry switch - EMAS-N: Network switch

WISE LAB

W-ATM Access Architecture (2)

• Access Point (AP) as Virtual Multiplexer

MT1

MT2

MT3

MT4

MT5

AP1

EMAS-E

VCPI=VPI=1VCPI=VPI=0

VCPI=VPI=0

VPCI=VPI=0

VPCI=VPI=0

VPCI=VPI=1VPCI=VPI=0

VPCI=0,VPI=0

VPCI=0,VPI=1

VPCI=1,VPI=2

AP2

VPCI=0

VPCI=1

VPCI=0

VPCI=0

VPCI=0

VPCI=0

VPCI=1

Port 2

Port 1UNI1

UNI2

UNI3

UNI4

UNI5

VPCI=0,VPI=0

VPCI=1,VPI=1

VPCI=0,VPI=2

VPCI=0,VPI=3

APCP-VC

APCP-VC

Fibre/coppercable

- MAC address uniquely identifies a logical port in the multiplexer:

(MAC address, VPI) VPI

WISE LAB

End-to-End Connection over W-ATM

• Protocol Stacks for a Full Integration of Mobile ATM Terminals to a Fixed ATM Network

Q.2931

ATM

M-LLC

PHY

SAALAAL

ATM

PHY

M-Ctrl

Q.2931

SAAL

User Service

M-MAC

M-PHY

User Service

M-Ctrl

SAAL

ATM

M-LLC

M-MAC

M-PHY

AAL

Q.2931

Mobile ATM Terminal Base Station Controller ATM Terminal

VCCend-pointUser plane

AT

M

Netw

ork

Wireless Channel

WISE LAB

- Data rate

25Mbit/sec available for user data transfer.Note that the user is considered to be the ATM layer (50K cells/sec).

- Packet Size

It is required that 1 cell / PDU can be implemented efficiently,but it is recognized that > 1 cell / PDU should be more efficientand so this should also be possible.

- Bit Error Rate

Bit error rate of 1E-4 at 99.5% availability measuredat the top of the PHY layer.

- Error Correction

It is a mandatory requirement that there is some EC.Block sizes to be consistent with packet size.

Physical Layer (1)

- Antenna

The PHY interface should be able to support antenna diversity.

- Estimated Maximum Range

Subject to local regulations and implementation option. - Indoors 30-50m - Outdoors: 200-300m

- Transmit Power

Local regulations set the limitations.(e.g., 100mW EIRP in Europe*, 200mW EIRP in US)

- Channelization

It is required that there be multiple physical layer channels. Channelizationchosen to be compatible with UNII.

• 5GHz Requirements (from WATM-WG ‘Baseline Text for Wireless ATM specification’)

WISE LAB

Physical Layer (2)

• Frequency Characteristics at 5.2GHz

- Fading rate can be almost 120 times greater

It is essential to usethe short packet

1 2 3

velocity(km/h)

frequency(MHz)

fading rate(sec-1)

average fadingduration (ms)

5 900 4.0 8.6100 900 80.6 0.43

5 5,200 23.3 1.5100 5,200 465.7 0.08

- Fading characteristics w.r.t. velocity & frequency band

fm / ; maximum doppler frequency

Ee

RfR

R

m

{ }

2 2

2

2

1; AFD

N Rf eR m

r

22

2

2

; fading rate

WISE LAB

Physical Layer (3)

64 kbps 25 Mbps 6 km 반경 셀비트 수소요시간 (

s)채널 효율소요시간 (

s)채널 효율

ATM 셀의 길이(Tt) 424 비트6784 86.39 % 17 26.33 %

전파지연시간(Tp)(해당사항없음) 40 0.51 % 40 61.96 %

Turn-around 시간(해당사항없음) 5 0.06 % 5 7.74 %

Header의 길이40 비트 640 8.15 % 1.6 1.48 %

Trail의 길이24 비트 384 4.89 % 0.96 1.49 %

• Channel Efficiency in High-Speed Wireless TDMA System

Time Slot

W-ATMHeader

W-ATMTrailerGT GTATM Cell

Tp

Tt

t

tTp

t

t

Tt 25 Mbps channel64 kbps channel

- How to improve the channel efficiency in high-speed wireless system?

WISE LAB

MBS HIPERLAN-I MEDIAN MagicWAND AWAData Rate E1: 40/80 Mbps

E2: 80/160 MbpsHBR: 23.53 MbpsLBR: 1.47 Mbps

155 Mbps 20 Mbps 50 Mbps (Oneway)

FrequencyBand

60 GHz 5.15 - 5.30 GHz 60 GHz 5.15 - 5.30 GHz 3 - 30 GHz (미정)

Modulation 4-OQAM16-OQAM

HBR: GMSK (BT=0.3)

LBR: FSK

(512,51)MCM

with QPSK

(16,?) MCMwith 8 PSK

QPSK/DifferentialDetection

ChannelCoding

BCH (31,26,3)

Physical Layer (4)

• Physical Layer Implementation for Broadband Wireless System

• Standardization

- No specific activities in W-ATM WG for the physical layer

WISE LAB

(8,4) binaryBlock code

BitInterleaver

QPSKor

DQPSK 64-p

oint

IDFT Circular prefix D/A U(f)

Cha

nnel

U*(f)A/DPrefix removal

64-p

oint

DFT

Matched Filtersor

DifferentialDetection

Optionalchannel estimator

Rea

l/Im

ag.

Dei

nter

leav

er

ML

deco

der

~

~

U V

64 bits 128 bits

I

64 complex symbols

I I I0 1 63, .....,i i i0 1 63, ....., i i i i i i49 48 63 0 1 63, ,..., , , .....,

T

T

fc

fc

r r r r r r49 48 63 0 1 63, ,..., , , .....,r r r0 1 63, .....,

RH

64 complex -valued symbols

R R R0 1 63, .....,

16~Ic

~I

8 16 real

symbols

U

4 = 64 16

bits

• MCM System for 155Mbps Transmission: Example

ATM Cell ATM CellATM Cell

DFTFrame15+64

DFTFrame15+64

DFTFrame15+64

DFTFrame15+64

DFTFrame15+64

DFTFrame15+64

DFTFrame15+64

StaticFrame

79

TDMA Frame

10.87 us

- Data Rate: 39 Mbps- Symbol Rate: (64+15) symbols / 10.87 us = 58.14 Msymbols/sec- Bandwidth Requirement: 70 MHz (< 20% roll-off factor)- Allowed Delay Spread: < 258 ns

Physical Layer (5)

WISE LAB

Error Control for Wireless ATM (1)

Data LinkARQ

ATM CellInt/Deint FEC Channel

Int/DeintModem

WirelessChannel

ATM CellsIn/Outs

(1) Forward Error Correction Coding - Header Protection - Payload Protection

(2) Interleaving - Channel Interleaver - ATM Cell Interleaver

(3) Data Link ARQ - Go Back N - Selective Repeat Request Mobility “M” Specification

Radio Access “R” Specification

User Plane

ATM Adatation Layer

ATM Layer

Medium Access Control

Data Link Control

Radio Physical Layer

WirelessControl

Control Plane

• Error Control Architecture

WISE LAB

Error Control for Wireless ATM (2)

header

ATM Cell

Coded Cell

FECParity

payloadHEC

payloadHEC

4 bytes 1 byte 48 bytes

• Forward Error Correction (FEC) Scheme: Single-Level FEC Scheme

Concatenated Coding: Convolutional Code + Reed-Solomon Code

- BER vs. CLR - Performance of Concatenated Coding

WISE LAB

Error Control for Wireless ATM (3)

TX

RX

HECDeletion

HECGeneration

FEC-1,FEC-2 : Error correctionCRC1 Error Cell discardPayload

HEC

Header

Standard ATM cell

Encoding

Header PayloadHEC

Encoding

Standard ATM cell

PayloadHeaderCRC

2CRC

1FEC

-1FEC

-2

Wireless ATM cell

EncodingEncoding

• Forward Error Correction (FEC) Scheme: Dual-level FEC Scheme

Header Protection:HEC (40,32) => FEC (28,16)(24 dB gain at CLR of 10-4, 75% increase in BW)

ATM Payload Protection: Variable Rate Error Control => Shortened Code ( n - l , k - l )

- Performance of Dual-level FEC Scheme

WISE LAB

Wireless ATM Cell Structure

B-RControl

B-R DataMobile 1

Uplink BurstMobile 2

Uplink Burst . . . .

B-R : Base-to-RemoteR-B : Remote-to-Base

Preamble

ControlPacket

R-B Control

PreambleFrame Header

WC 1 WC 2 ...... WC N

WirelessHeader

ATMHeader

CRC FEC Payload CRC FEC

Preamble

• MAC Frame and W-ATM cells

- Example 1:

- Example 2:

B-RControl

B-R DataMobile 1

Uplink BurstMobile 2

Uplink Burst . . . .

Preamble

R-B Control

PreambleFrame Header

WirelessHeader

ATMHeader

Payload CRCPayload........

WISE LAB

Error Control for Wireless ATM (4)

48 bytes

ATM cell

30

5bytes

321

40

Header

48bytes

400

30

10

60

5 bytes

70

20

40

50

Interleaved cell

Interleaved

• Interleaving: to randomize channel burst errors

(2) ATM Cell Interleaver(1) Channel Interleaver

1 2 3

1 2 3 4 5 6 7 8 9 10 11 12 13 1415 16 17 18 19 20 2122 23 24 25 26 27 28

Interleaved Sequence: [1,8,15,22,2,9,16,23, .....]

1 2 3 4 5 6 7 8 9 10 11 12 13 1415 16 17 18 19 20 2122 23 24 25 26 27 28

Fading Channel

Received Sequence: [1,8,15,22,2,9,16,23, .....]

Deinterleaved Sequence: [1,2,3,4,5,6,7,8,9,.....,14,15, 16,.....,21,22,23,......,27,28]

WISE LAB

Error Control for Wireless ATM (5)

• Data Link ARQ

- Go Back N vs. Selective Repeat Request:

BER to required for efficiency of 80% (30-cell packet)

- Overhead equivalent to TCP/IP over AAL5

Selective Repeat ARQ Go Back N ARQ Link Type DS1 DS3 OC-3 DS1 DS3 OC-3Terrestrial

(Cross-country)10-5 10-5 10-5 10-5 3 * 10-7 10-7

Satellite (GEO) 10-5 10-5 10-5 5 * 10-7 2 * 10-8 5 * 10-9

- Throughput efficiency of Go Back N vs. BER

• ARQ Protocol Parameters

- Retransmission time out- Window Size- Tx & Rx Buffer Size- ARQ Protocol Frame Length

- BT >> 1 & or large BER => Selective Repeat Request

• ARQ Protocol for Wireless ATM

Example: ASR-ARQ Protocol proposed for MBS - Multiple ARQ instances => one ARQ instance per VC - Delayed cell discarded

WISE LAB

Wireless MAC Layer

PHYDLCSAR

&Shaper

SourceCoder

MACW-ATM NIC

DynamicParameters

PHYDLCSAR

&Shaper

SourceCoder

MACW-ATM NIC

DynamicParameters

PHY DLC

CAC

ATMNIC

SupervisaryMAC

W-ATM NIC

DynamicParameters

ATM Network

Radio ATM PortATMPort

UPC and QoS Renegotiation

Reservation Request/Dynamic Prameters/

Slot Assignment

QoS & UPC

QoS& UPC

• The MAC protocol is the pivot between the ATM world and the wireless world

- Provides means to share the wireless channel among mobile terminals with varying data rates and QoS requirements

WISE LAB

Fibernode

Head-endor

centraloffice

FiberCoax

CATVantenna

PSTN

Toservices

Toservices

ATMNetwork

W-ATM MAC as a Distributed ATM Switch

SAALQ.2931

PHY

M-Ctrl

W-LLC

User Service

AAL SAAL

ATM

PHY

Q.2931

W-PHYPHY

W-LLCW-MAC

M-Ctrl

ATM

User Service

AAL SAAL

ATM

PHY

Q.2931

W-PHYPHY

W-LLCW-MAC

M-Ctrl

ATM

User Service

AAL SAAL

ATM

PHY

Q.2931

W-PHYPHY

W-LLCW-MAC

M-Ctrl

ATM

W-MACW-PHY

ATM

Base station

Wireless ATM terminal

ATM multiplexer

• HFC Networks • W-ATM Networks

WISE LAB

무선 ATM 에서의 매체접근제어 요구 사항

일반적인 MAC 프로토콜 요구 사항 무선 MAC 프로토콜 요구 사항 무선 ATM MAC 프로토콜 요구 사항

- Fault Tolerance

- Scalability

- Throughput

- Delay

- Addressing

- Support for Asymmetric Traffic

- Fairness

- Support for Broadcasting and

Multicasting

- Data Reliablity

- Transparency

- Power Efficiency

- Fading Immunity

- To Handle Hidden Terminal Problem

- Simplified Frame Structure

- Support Handoff & Roaming

- To support all ATM traffic classes

- To guarantee QoS Requirements for

each traffic class

- To design a MAC PDU for an efficient

transmission of ATM cells

- Error Control: MAC layer CRC

• 무선 ATM 매체 접근 제어 방식이 기존 방식이 무엇이 다른가 ?

- 다양한 서비스 트래픽을 어떻게 통합된 접속 구조에서 수용할 것인가 ?

WISE LAB

- Logical channelsA mobile requires multiple logical data channels. Each is associated with QoS/traffic parameters.Each is also associated with an ATM VPI,VCI pair and a direction

- QoS/Traffic parameters: (see TM 4.0)QoS/Traffic parameters are established at ATM call setup and must be provided to the MAC.

- QoSQoS/Traffic parameters must be met at the MT and at the AP to switch interface.While they should be met at the AP/RP to MT interface the requirement for sharing the medium may require this to be relaxed.Note that the end to end QoS should not be compromised.

- ArchitectureIt is a mandatory requirement that the MAC architecture is for last hop access using centralized control.It is an optional requirement that the MAC may support ad-hoc configuration.

- Service ProvisionIt is a requirement to be able to support all ATM service classes.It is a requirement that MAC efficiency be 60 - 75%, and that it data rates supported includeat least 10Mb/s peak (optionally peak per connection is the total available cell rate), 6Mb/s sustained,32kb/s minimum on a connection.

무선 ATM 에서의 매체접근제어 요구 사항

• 5GHz Requirements (from WATM-WG ‘Baseline Text for Wireless ATM specification’)

WISE LAB

VOD

Broadcast

POTS

Video phone(CBR)

VideoConferencing

Telecommuting

Desktop Multimedia

Distance Learning

Video phone (VBR)

Electronic content distribution

Interactive TV down stream

Image networking

Interactive game

Call setup

Interactive TVupstream

VCR control

¿ä±¸ Áö¿¬ ½Ã°£

Burstiness

FixedAssignment

(°íÁ¤ ÇÒ´ç ¹æ½Ä)

Reservation(¿¹¾à ¹æ½Ä)

Contention(°æÀï ¹æ½Ä)

Access Control Protocol Options

• Different types of services may be best served by different access control protocol choices

WISE LAB

무선 ATM 매체 접근 제어 모델

( )1

( )2

( )n

하향 링크 스케쥴러

상향 링크 스케쥴러

DynamicParameter전송(in-band 또는out-of-band)

( )1

( )2

( )n

상향 링크

하향 링크

슬롯 할당 결과 통보

이동국 기지국

• Generic MAC Model

• Scheduler

- responsible for dynamic slot assignment- based upon the static and dynamic parameters

WISE LAB

Packet Reservation Multiple Access (PRMA)

• PRMA: Reservation ALOHA for Microcellular Environment - real-time transmission constraint for packet voice - voice activity detection for throughput improvement

• Operational Concept of PRMA

(1) A MT a with a new talkspurt to transmit sends the first packet on the first available time slot which is permitted for MT a with a probability p.

MT BS

Frame

R R R

MT BS

P

(2) If the first packet is transmitted successfully, BS reserves the slot P to the MT a.

(3) If the first packet collides, the MT a retransmits on the next available and permitted slot.

Reservation Indicated

WISE LAB

Integrated PRMA (I-PRMA)

1 2 3 ...... Nr 1 2 3 ............... Nv

Request Slots Voice Slots Data only

TDMA Frame (T sec.)Frame

Overhead

GuardTime

Sync &Overhead

Request Data(User ID’s)

GuardTime

GuardTime

Sync &Overhead Voice Data Guard

Time

• I-PRMA Frame Structure

• Integration of Voice & Data

WISE LAB

»óÇâ ¸µÅ©

ÇÏÇâ ¸µÅ©

È®ÀÎÀÀ´ä(ACK)

¿¹¾à(RES)

RACHRACH

- Static parameters (call setup parameters) : mean bit rate, peak bit rate (QoS)

- Dynamic parameters : waiting period of the cell in a queue, current queue length

• Frame structure

Empty Queue

AccessRACH

with call setupparameters

New packet?

ACK?

Listenall downlik slots

Next slotReservation

Yes

Yes

Yes

No

NoNo

Yes

No

Queue empty?

• Flow Chart for DSA Protocol

• Dynamic Slot Assignment (DSA) - Proposed for RACE MBS (Mobile Broadband System)

• Scheduling parameters

Dynamic Slot Assignment (1)

WISE LAB

Dynamic Slot Assignment (2)

• Strategies to minimize the contention

(1) Periodically broadcasting state parameters ( e.g. Setting probability of transmission according to the current load of RACH )

(2) Increasing density of RACH ( e.g. Using subslots )

(3) Inserting sufficient RACH by calculating priority for RACH

Pa

b lr

( ) logpriority

P c r f( )priority

r

c

f

mean rate

time passed since

last successful transmission

scaling coefficient

r

l

a b

residual lifetime

queue length

scaling coefficient,

• Slot assignment strategies in BS

Reservation Mode Contention Mode

WISE LAB

DSA++

• Disadvantages of DSA

(1) BS point of view - Difficult to perform power control(2) MT point of view - Difficult to implement a power saving mode - Difficult to find a channel for fast and seamless handovers

DownlinkSignallingBurst

• Downlink signalling scheme of DSA++

DownlinkSignalling

Burst

Downlink Signalling Period

Announcement

ReservationFeedback

Uplink Signalling PeriodOffset

Downlink

Uplink RACH RACHRACH

(1) Reservation message

- uplink slot reservation

(2) Announcement message

- downlink transmission

- downlink signalling burst slot

(3) Feedback message

- ACK for RACH

(4) System signalling messages

- paging channel

- info channel, etc.

WISE LAB

Uplink Downlink

Slot kSlot k

Packet Transmission Channel

Request AccessChannel

Piggybacking Request Bit(Contention Free)

Packet Transmission Channel

ACKChannel

Packet TransmissionPermission Channel

REQUESTACCESS

CHANNEL

REQUESTTABLE

(Collision-free)PIGGYBACKINGOF REQUESTs

PACKETTRANSMISSION

CHANNEL:

λ 1

λ 2

λ N

Mobile Terminals Base Station

Control flow

Request flow

Packet flowfeedback

• Block Diagram of DQRUMA

• Uplink & Downlink Structure

• Distributed Queue Reservation Update Multiple Access for BAHAMA (AT&T Bell Lab.)

DQRUMA

WISE LAB

1 OFDM Symbol (512 points) = 1 ATM Extended Cell

ATM Cell to PS 1Broadcast Symbol

Null&Ref. Symbol

ATM Cell to PS 2

Cell from PS 2Cell from PS 2Cell from PS 2

Cell from PS 1Cell from PS 1

Cell from PS 1Frame

downlink

uplink

Adaptive TDD

123

kk+1

626364

1 OFDM block

1) Null Symbol2) Reference Symbol

3) Broadcast Cell (Slot Allocation Table)Table)

4) ATM Cell (424 bits)bits)4) Signaling

Coding

Coding

(1024 bits)1024 bits

• ATDD frame & extended cell structure

• Adaptive PRMA (Packet Reservation Multiple Access)

Wireless ATM MAC Example (1)

• MEDIAN - ATTD (Adaptive Time Division Duplexing)

WISE LAB

• MASCARA (Mobile Access Scheme based on Contention And Reservation for ATM)

Variable Length Time Frame

UpDownFH

Contention based

Contention

VariableBoundary

VariableBoundary

VariableBoundary

Reservation basedBroadcast

TimeRadioturn-around

From AP to MT From MT to AP

..... .....

• MAC time frame structure

• MPDU & Cell Train Concept

Wireless ATM MAC Example (2)

PHY & MPDU headers MPDU body : Cell trains of 3, 4, 2 and 1 ATM cells

Time slot

1st MPDU 2nd MPDU 3rd MPDU 4th MPDU

WISE LAB

MAC 프로토콜 AccessDuplexing

패킷 다원접속 방식

예약요청 방식

프레임길이

상하량 링크프레임 길이

슬롯 할당결과의 통보

MBSDSA:

Dynamic Slot AssignmentDSA++

TDMA 동적 예약 방식경쟁 /폴링

DSA:고정

DSA++:가변

not specified

DSA:슬롯 단위

DSA++:프레임 단위

MEDIANDynamic PRMA: Packet

Reservation Multiple AccessTDMA/TDD

동적 예약 방식 경쟁 고정 가변(Adaptive TDD)

프레임 단위

MagicWAND

MASCARA:Mobile Access

Scheme based on ContentionAnd Reservation for ATM

TDMA/TDD

동적 예약 방식 경쟁 가변 가변(Adaptive TDD) 프레임 단위

BAHAMADQRUMA:

Distributed Queue RequestUpdate Multiple Access

TDMA/TDD

동적 예약 방식 경쟁 고정 not specified 슬롯 단위

WATMnetMDR:

Multiservice DynamicReservation

TDMA/TDD

동적 예약 방식 경쟁 고정트래픽 클래스간가변 프레임 길이

프레임 단위

SWANEC-MAC:

Energy Conserving MACTDMA/TDD

동적 예약 방식 비경쟁 고정 가변 프레임 단위

일본우정성

CRL

RS-ISMA: Slotted Idle Signal Multiple

Access with Reservation

TDMA/FDD

동적 예약 방식 경쟁 notspecified

not specified not specified

무선 ATM 매체 접근 제어 구현 사례 비교

WISE LAB

B-RControl

B-R DataMobile 1

Uplink BurstMobile 2

Uplink Burst . . . .

B-R : Base-to-RemoteR-B : Remote-to-Base

UBR ABR VBR CBR

Preamble

SlottedALOHA

ControlPacket

Preamble

R-B Control

°¡º¯ °æ°è

PreambleFrame Header

프레임 구조 (1)

• MDR-TDMA (Multi-service Dynamic Reservation TDMA) Protocol in WATMnet

WISE LAB

1 1N2 212 . . . . . N . . . . . J-N

DATA

PILOT

DATADATA

PILOT

±âÁö±¹¿¡¼ À̵¿±¹À¸·ÎÀÇÈ®»ê ½ÃÄö½º

±âÁö±¹ÀÌ À̵¿±¹¿¡½½·Ô ÇÒ´çÀ»

Å뺸Çϱâ À§ÇÑpolling¿¡ »ç¿ë

POLLINGSEGMENT

DATA SEGMENT

Subfield 1 Subfield 2

À̵¿±¹¿¡¼ ±âÁö±¹À¸·ÎÀÇÈ®»ê ½ÃÄö½º

±âÁö±¹ÀÇ ¾ÈÅ׳ª weightÁ¶Á¤¿¡ »ç¿ë ±âÁö±¹ÀÇ ¾ÈÅ׳ª weight

Á¶Á¤¿¡ »ç¿ë

À̵¿±¹ À̵¿±¹±âÁö±¹ ±âÁö±¹

프레임 구조 (2)

• Pilot-Assisted MAC

W 1

W k

W 2

Arrayprocessor

Co-channelinterference

Reflections

Co-channelinterference

Antennaelement

Low-noiseamplifier

- “Adaptive MAC Protocol in Harsh Fading and Interference” (Acampora ’97)

WISE LAB

프레임 구조 (3)

• MAC Frame proposed by Fujitsu (ATM Forum/97-0783)

- Multiple types of MAC frames to enhance the wireless efficiency

Preamble(16 octets)

Control(2 octets)

Address(6 octets)

Header(4 octets)

Payload(48 octets)

CRC(2 octets)

Guard(2 octets)

(1) Frame Type 1: low-bandwidth type of traffic (e.g., voice traffic)

(2) Frame Type 2: high-bandwidth type of traffic (e.g., IP traffic)

Preamble(16 octets)

Control(2 octets)

Address(6 octets)

Header(4 octets)

Payload(48 octets)

CRC(2 octets)

Guard(2 octets)

Payload(48 octets)

Type-1 Frame = 80 octets (48 octet payload + 32 octet overhead)

Type-2 Frame with 6 cells = 320 octets (48 x 6 octet payload + 32 octet overhead)

Example:

- Efficiency vs. Frame Type

# of ATM payloads Efficiency # of TDMA slots

1

4 80 %

1 60 %

4 90 %6

3

. . .

WISE LAB

슬롯 할당 방식 (1)

트래픽트래픽 파라미터스케쥴링 알고리즘슬롯 할당 주기CBR max, 주기적 고정 할당 1/VBR max,,d 동적 슬롯 할당비주기적 할당

ABR해당 사항 없음동적 슬롯 할당

(다중 슬롯 랜덤 접속 / 폴링)해당 사항 없음.

• 트래픽별 슬롯 할당 방안

• 무선 구간에서의 통계적 다중화 구현이 가능한가 ?

( )1

( )2

( )n

하향 링크 스케쥴러

상향 링크 스케쥴러

DynamicParameter전송(in-band 또는out-of-band)

( )1

( )2

( )n

상향 링크

하향 링크

슬롯 할당 결과 통보

이동국 기지국

) ( :

) ( :

max jittertolerableimummax

sourceofrate

편차시간지연허용최대발생률트래픽

) ( :

) ( :

) ( :

max delaytolerableimummaxd

burstinessimummax

rateofaverage

시간지연허용최대버스트율최대

발생률트래픽평균

WISE LAB

슬롯 할당 방식 (2)

¹«¼± ATMMAC ¿ä±¸ »çÇ×

Æ®·¡ÇÈ º° QoSÀÇ º¸Àå

Åë°èÀû ´ÙÁßÈ À̵æÀÇ ±Ø´ëÈ

ATM ¿ä±¸ »çÇ×

DynamicParameter

(DP)

µ¿Àû ½½·Ô ÇÒ´ç

½½·Ô ÇÒ´ç ¾Ë°í¸®Áò

½½·Ô ÇÒ´ç ¾Ë°í¸®ÁòÀÇ ¿ä±¸ »çÇ×

DP ³»¿ªÀÇ ´Ü¼øÈ

DP Àü¼ÛÀÇ È¿À²¼º±Ø´ëÈ

½½·Ô ÇÒ´ç ¹æ½ÄÀÇ ´Ü¼øÈ

ä³Î »ç¿ë È¿À²¼ºÀDZشëÈ

CBR

VBR

ABR

°íÁ¤ ½½·Ô ÇÒ´ç

• 슬롯 할당 방식의 구현 요구 사항

WISE LAB

• Estimation-Prorated Slot Assignment for VBR traffic (in WATMnet)

e lij

ij

ij

1 1 1( ) ( ) ( )

ij( )

lij( )

(1) Down-link Estimation: e lij

ij

ij

1( ) ( ) ( )

(2) Up-link Estimation

Out-of-band Control:

In-band Control:

Estimated by the mobile terminal

if r e aij

ij

0 10 ( ) ( ) ;

if r e aij

ij

1 11 ( ) ( ) ;

if

else

a a e a

e a a a

ij

ij

ij

ij

ij

ij

ij

ij

( ) ( ) ( ) ( )

( ) ( ) ( ) ( )

;

;

1 1

1 1

1

else

Estimated by the base station

Mobile Terminal

b b0 1

WATM Cell

b b

l l b

l l b

ij

ij

ij

ij

0 1

1 2 0

1 2 1

0

1

1

if then

if then

( )

( )

( ) ( )

( ) ( )

eij1

( )

TDMA Frame

RequestSlots CBR Slots VBR Slots + Data Slots

ReservationMinislots

(Slotted ALOHA)

1 2 3 ....... Nv Nv+1 ....................................... Nt

Movable Boundary

슬롯 할당 방식의 예

WISE LAB

결 론

• 물리 계층

• 데이터 링크 계층

• 매체 접근 제어 계층

- 고속 무선 전송 기술 (> 25 Mbps)

- Multi-carrier Modulation Modem

- 동적 예약 (Dynamic Reservation) TDMA/TDD

- 트래픽 클래스 별 QoS 보장을 위한 스케쥴링 알고리즘- 프레임 구조 ( 전력 효율성 , 대역 효율성 , 페이딩 , Dynamic Parameters)

- 셀 헤더 (Header) 보호를 위한 오류 정정 부호화 (FEC)

- 무선 셀에 대한 오류 정정 부호화 및 재전송 프로토콜 (ARQ)

- 무선 셀 및 프레임 구조의 최적화