1 Merges of Wireless Communications and Computer Networks George Lee

2 Abstract (1) Merge ATM technology in Wireless Communications Network –ATM Wireless Network (ATM as wireless network’s backbone) Merge Wireless technology in LAN/ATM networks –Wireless LAN and Wireless ATM  WLAN:ETSI HIPERLAN(Ad hoc network) IEEE (Infrastructure network)  WATM:ACTS (Lucent, NEC, Magic WAND) ATM Forum WATM WG (1999 ?)

3 Abstract (2) Issues in ATM Wireless Network –QoS  Voice-Operated Transmission (VOX) Diversity Handoff Layered 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,...

4 Introductions Evolution of wireless communications: Evolution of computer networks: –LAN Ethernet, Fast Ethernet, Gigabit Ethernet FDDI ATM –WAN X.25 Frame relay ATM

5 Evolution of mobile multimedia services (Nakamura et. Al)

6 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 communications in LAN/ATM –Portability + Networking

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

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

9 References H. Nakamura et. al, “ Applying ATM to Mobile Infrastructure Networks, ” IEEE Communications Magazine, Jan Pahlavan et. al, “ Wideband Local Access: Wireless LAN and Wireless ATM, ” IEEE Communications Magazine, Nov Crow et. Al, “ IEEE Wireless Local Area Networks, ” IEEE Communications Magazine, Sep Passas et. al, “ Quality-of-Service-Oriented Medium Access Control for Wireless ATM Networks, ” IEEE Communications Magazine, Nov

10 4 Phases of ATM introduction to mobile networks Nakamura et. al 1 2A 2B 3 4

11 Requirements of ATM wireless infrastructure Nakamura et. al Power efficiency  Voice-Operated Transmission (VOX) BS  MSC  STM  ATM

12 Nakamura et. al QoS  Diversity Handoff: MS  BS  BSC  STM  ATM

13 Nakamura et. al To reduce ATM Packetization delay  Layered cell: Multiplexing in BS  BSC Nakamura et. al Multiplexing CPS=Common part sublayer

14 Wireless LAN 2 types of networks: Defined in –Physical layer –Media Access Control layer

15 (1) Ad hoc network STA = Station BSS = Base Service Set

16 (2) Infrastructure network STA = Station BSS = Base Service Set AP = Access Point ESS = Extended Service Set 802.3, 802.4, 802.5, 802.6, or FDDI Backbone

17 IEEE BSS & ESS STA, 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

18 IEEE (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.

19 ETSI HIPPERLAN ad hoc network

20 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 transport Isochronous transport

21 Wireless ATM Architecture AP

22 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

23 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

24 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 )

25 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