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Merges ofWireless Communications

andComputer Networks

George Lee

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Abstract (1)• Merge ATM technology in

Wireless Communications Network– ATM Wireless Network

(ATM as wireless network’s backbone)

• Merge Wireless technology inLAN/ATM networks– Wireless LAN and Wireless ATM

WLAN: ETSI HIPERLAN (Ad hoc network) IEEE 802.11 (Infrastructure

network)WATM: ACTS (Lucent, NEC, Magic WAND)

ATM Forum WATM WG (1999 ?)

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Abstract (2)• Issues in ATM Wireless Network

– QoS Voice-Operated Transmission (VOX)

Diversity HandoffLayered Cell

• Issues in Wireless LAN/ATM– Frequency allocation, Throughput, Mobility,

Access Methods for Mobile Interface,Interference and Reliability, QoS,Mobile TCP/IP, TCP/IP over ATM, Security,Power Consumption, Human Safety,...

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Introductions• Evolution of wireless communications:

• Evolution of computer networks:– LAN

• Ethernet, Fast Ethernet, Gigabit Ethernet

• FDDI

• ATM

– WAN• X.25

• Frame relay

• ATM

Generation Voice Signaling Data Examples1st analog digital AMPS2nd digital digital low bit rate GSM, IS-54, IS-953rd digital digital ~ N-ISDN PCS/PCN, UMTS, IMT-20004th digital digital ~ B-ISDN ?

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Evolution of mobile multimedia services

(Nakamura et. Al)

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• The need for ATM in mobile infrastructure– Variable bit rate ( different traffic types)

• Voice, FAX, video conference, ...

– Wide range of bit rate ( different traffic types)• from low bit rate voice and data to high bit rate video

– Asymmetrical communications ( server > client)• WWW, VOD, …

– Point-to-Multi-point:• VOD

• The need for mobile communicationsin LAN/ATM– Portability + Networking

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Merges of Wireless Communications and Computer Networks (3rd gen.)

PSTN

Handset

Packet Network(Internet)

Mobile Computer

Fixed Phone Cordless Phone

Wireless ATM Core Network

Wired LAN

Wired LAN

MSC 。。 MSC 。。

BS BS AP

Wireless ATM

APAP

Wireless LAN

APBS BS

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Merges of Wireless Communications and Computer Networks (4th gen.)

PSTN

Handset

Packet Network(Internet)

Mobile Computer

Fixed Phone Cordless Phone

Wireless ATMCore Network

Wired LAN

Wired LAN

MSC 。。 MSC 。。

BS

Wireless ATM

BS BS

Wireless ATM

BS AP

Wireless ATM

APAP

Wireless LAN

AP

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References• H. Nakamura et. al, “Applying ATM to Mobile Infrastructure Networks,” IEEE Communications Magazine, Jan. 1998.

• Pahlavan et. al, “Wideband Local Access: Wireless LAN and Wireless ATM,” IEEE Communications Magazine, Nov. 1997.

• Crow et. Al, “IEEE 802.11 Wireless Local Area Networks,” IEEE Communications Magazine, Sep. 1997.

• Passas et. al, “Quality-of-Service-Oriented Medium Access Control for Wireless ATM Networks,” IEEE Communications Magazine, Nov. 1997.

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4 Phases of ATM introduction to mobile networks

Nakamura et. al

1 2A

2B 3

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Requirements of ATM wireless infrastructure

Nakamura et. al

• Power efficiency Voice-Operated Transmission (VOX) BS MSC STM ATM

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Nakamura et. al

• QoS Diversity Handoff: MS BS BSC STM ATM

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Nakamura et. al

• To reduce ATM Packetization delay Layered cell: Multiplexing in BS BSC

Nakamura et. al

Multiplexing

CPS=Common part sublayer

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Wireless LAN• 2 types of networks:

• Defined in– Physical layer– Media Access Control layer

Types ExamplesAd hoc HIPERLAN I & 802.11Infrastructure 802.11

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(1) Ad hoc network

STA = Station

BSS = Base Service Set

802.11

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(2) Infrastructure network

802.11

STA = Station

BSS = Base Service Set

AP = Access Point

ESS = Extended Service Set

802.3, 802.4,802.5, 802.6,or FDDI Backbone

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IEEE 802.11

• BSS & ESSSTA, AP, Portal (See Figure 1 & 2)

• 2 types of traffics:

– DCF = Distributed Coordination Function•CSMA/CA•Contention-based Ad hoc/Infrastructure

– PCF = Point Coordination Function•AP-controlled polling Infrastructure

Types Packet Loss Delay Examples MethodAsynchronous Not allowed Allowed E-mail, FTP DCFTime-bounded Allowed Not allowed Voice, Vedio PCF

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IEEE 802.11 (cont.)• 3 types of PHY layers:

– FHSS (Frequency Hopping Spread Spectrum)

– DSSS (Direct Sequence Spread Spectrum)– IR (infrared)

• 2 modes in MAC– Contention mode: DCF only– Switching mode: switch between

•Contention Period (CP): DCF•Contention Free Period (CFP): PCF

• 3 kinds of MAC frames– Management, Control, Data.

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ETSI HIPPERLAN ad hoc network

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ETSI HIPPERLAN ad hoc network• Multi-hop ad hoc

– 2 types mobile stations:•Non-Forwarder: receives its own frames only

•Forwarder: receives all frames and forward– Multi-hop routing protocol

•Between Forwarders• MAC

– Non-Preemptive Multiple Access (NPMA)– LBT (Listen Before Talk)– Asynchronous transportIsochronous transport

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Wireless ATM Architecture

AP

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Wireless ATM architecture• ACTS (Advanced Communications Technologies and Services)

(Lucent, NEC, Magic WAND)ATM Forum WATM WG (1999 ?)

• Magic WAND (Wireless ATM Network Demonstrator)– 4 kinds of components

• Mobile Terminals (MT), Access Points (AP), ATM Switches (SW), Control Station (CS).

– MASCARA (Mobile Access Scheme Based on Contention and

Reservation for ATM) • ATM layer Radio PHY layer

• TDMA: variable-length time frames &dynamically allocated fixed-length time slots

• Mixed use of Contention, Reservation, & Polling

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Conclusion (1)• Frequency allocation

– Possible Freq. Bands• 2.4 GHz ISM

• 1.9 GHz U-PCS

• 5 GHz U-NII

– Bit rate improved by• smaller packet

• higher freq. Band

• new mod. tech.

• Throughput– Current: 2-20 Mbps– Goal: Higher bit rate

• Mobility– Handoff schemes– Rerouting schemes

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Conclusion (2)• Access Methods for

Mobile Interface– Wireless Comm.:

• TDMA

• FDMA

• CDMA

– Wireless LAN/ATM:

• TDMA– FDMA ABR ?

– CDMA bit rate?

• Interference and Reliability– Multi-path fading

– ARQ or FEC (Automatic Repeat Request)(Forward Error Correction)

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Conclusion (3)• QoS

– Voice:• CBR/AAL 1

– IP datagram:• UBR|ABR/AAL 5

BER? Handoff ?

• Mobile TCP/IP– MS freely moves:

• TCP connection ?

• IP address ?

• TCP/IP over ATM– IP over ATM ?

– LAN Emulation?

– IP Switching ?

– Tag Switching ?

– Multi-Protocol over ATM ?

• Security– Encryption

• Power Consumption

• Human Safety