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G-W-LAN (Gigabit wireless LAN)

G-WLAN is a Gigabit Wireless LAN technology that aims to provide high-speed data communications for wireless devices. This article discusses the problem definition, background, requirements, and detailed description of three issues. It also provides solutions for these issues and compares different methods in terms of pros and cons. The article concludes with an overview of G-WLAN, its motivation, and existing and future challenges.

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G-W-LAN (Gigabit wireless LAN)

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  1. G-W-LAN(Gigabit wireless LAN)

  2. Agenda • Problem Definition 2-3 • Background 3-5 • Requirements • Detailed Description of 3issues 10-15 • Sol for issues --- describe method in Lit. Ser. 2-5 • Pro’s & Con’s for each method including the comments 2-3 • Comparison W.R.T. background 2-3 • Conclusion 4-10

  3. Outline: - • What is G-W-LAN? • Why G-W-LAN? • What is it motivation? • What is it’s motto? • What is the amount of work done in this area? • Is there any earlier deployment of the similar type? • What kind of work/research going on in this area? • What are existing challenges/bottlenecks in this area? • Are there any future challenges?

  4. What is GWLAN? • What is WLAN? • How it came into existence? • What protocol is used in WLAN? What is its Architecture of WLAN? • What are the problems in WLAN? • Is there any standards?

  5. Overview of WLAN(Journey/path towards GWLAN)

  6. Wireless LAN Evolution 1945 spreadspectrumtechnologyused 1986 early WLAN products on market 1990 IEEE 802 initiates WLAN standard 1995 ETSIspecifies20Mbit/sHIPERLAN 1997 IEEE 802.11 2Mbit/s WLAN standard 1999 WECAchecksproductcompliance 1999 IEEE 802.11b 11Mbit/sWLAN standard 2000 WLANA established to educate market

  7. Radio Free Space Propagation 2 Pr Pt \ 4 r Gr Gt = r Tx Rx Pt = transmit Power Pr = Receiver Power Gt = Antenna Gain Gr = Antenna Gain

  8. Multipath Distortion echo echo echo Tx Rx t

  9. Fading Effects Tx Rx position

  10. Shadowing Tx Rx shadow Rx

  11. Radio Indoor Propagation Attenuation (dB) n = 3.7 (Retail) n n = 3.3 (Office) Loss o < [distance] n = 2 (Free Space) Distance (m)

  12. Radio LAN Capabilities Mbit/s Metres In-building Range Bandwidth 900 MHz 1.8 GHz 2.4 GHz 5.6 GHz 17GHz 24 GHz 60 GHz

  13. IEEE 802.11 WLAN Architecture Higher-Level Protocols Data Link Layer Wireless MAC Wire Equivalent Privacy PHY 1 FH-SST PHY 2 DS-SST PHY 3 Infra-Red Physical Layer

  14. Direct Sequence Spread Spectrum (DSSS) amplitude amplitude freq freq baseband signal transmitted signal Random Spreading Code transmission amplitude amplitude freq freq signal recovery received signal

  15. Frequency Hopping Spread Spectrum (FHSS) amplitude amplitude freq freq baseband signal transmitted signal Random Hopping Sequence transmission amplitude amplitude freq freq signal recovery received signal

  16. Infra-Red LAN Capabilities Speed (Mbit/s) 10 docking station Directed Point-to-Point Building-to-Building 1 Diffuse Distance (metres) 10 100 1000

  17. IEEE 802.11 WLANs • spread spectrum & IR supported • 2.4 GHz ISM band for world-wide • CSMA with Collision Avoidance • initially 1+2 Mbit/s raw data rates • ~70m in-building range @ 100mW • wire-equivalent privacy mode • power management facility

  18. Supported Topologies backbone network base station base station Peer-to-Peer Hierarchical

  19. 802.11 Wireless LAN Family • 802.11 Original Wireless LAN in 2.4 GHz band • 2 Mbit/s with poor signal fallback to half rate • supports ad hoc & infrastructure configurations • 802.11a Enhanced Wireless LAN in 5 GHz band • 54 Mbit/s peak bit rate supported • 27 Mbit/s average throughput • 802.11b Enhanced Wireless LAN in 2.4 GHz band • 11 Mbit/s with poor signal fallback to half rate • 4-5 Mbit/s average throughput

  20. 802.11 Wireless LAN Family • 802.11e WLAN QoS Enhancements • introduces QoS facilities to support voice/video • designed to support 802.11a and 802.11b • also improves mobile and nomadic use • 802.11g Higher-speed WLAN in 2.4 GHz band • extends 802.11b to 20-54 Mbit/s via Orthogonal FDM • backwards-compatible with 802.11b devices • 802.11h Higher-speed WLAN in 5 GHz band • extends 802.11a for European CEPT frequencies

  21. 802.11 Wireless LAN Family • 802.11i Enhanced WLAN Security • definition of powerful wireless LAN security • encompasses 802.1X, TKIP & AES protocols • includes authentication and encryption • 802.11n High Throughput WLAN • targeting bit rates >100 Mbit/s, up to 250 Mbit/s • both 2.4 GHz and 5 GHz band being considered • standardisation completion planned for end 2005 • Future Generation WLAN Think Tank • proposal for Gigabit WLAN in 56+GHz bands, with lower cost than GBE over cable for 2005-6

  22. IEEE 802.11 standards and HiperLAN2

  23. Evolution of Gigabit Wireless LANs Phase 3 Enterprise grade Gigabit Ethernet wireless-to-the-desktop Enterprise Gi Fi Phase 2 54M @ 2.4GHz 802.11g SMEs security QoS Phase 1 802.11i 802.11e 54M @ 5.7GHz 802.11a 2M @ 2.4GHz Home/ SOHO 802.11b 11M @ 2.4GHz 802.11 2000 2005

  24. Motivation for GWLAN: - • Increase in the use of wireless devices. • Significant growth in Wireless local area networks (WLAN’s) as they provide a data-based complement to wireless voice-based cellular networks. • Resulted in • Raise in demand for high-speed multimedia data communications, such as a huge data file transmission and real-time video streaming. • Markedly increasing wireless transmission with 1Gbps and beyond data rate became very essential.

  25. Existing Issues: : - • Delay Spread in Radio Channel (Asymmetric Equalization) frq. • MIMO. • High Capability Antennas.

  26. Other Issues: - • Compatibility with different application and devices. • Hardware Synchronization / Hardware Design Aspects • Hardware at the end user (Rx) • Hardware at the Base Station (Tx). • Handoff (interoperability in the Local LAN with different AP’s). • Cost of Design, Deployment and Maintenance.

  27. Other challenges: - • Coverage Area (Signaling distance). • Through-put. • Power. • Robustness. • Quality of Service (Error Rate, Packet lost, etc). • Performance. • Co-Existence with existing system. • Issues pertaining to Outer door and indoor environment.

  28. Roadmap – WLAN

  29. Deployment scenarios

  30. Home environment • Video streaming • 20 MBit/s high quality • 3 hops • MAC overhead • 100 MBits/s • Internet download: 100 Mbit/s • Audio (multi hop): 30 MBit/s • Multiple users & applications • Highly bursty traffic • 1 GBit/s required • Self-configuration, zero maintenance • Ad-hoc and multi-hop capabilities Key challenges: ease of use, robustness, QoS

  31. Enterprise environment • WLAN brought wireless interconnection to the office • Work becomes detached from the desk • 100baseT and 1000baseT are state-of-the-art • Wireless Gigabit required to match enterprise demands • VoIP and video conference systems necessary in enterprise environments • QoS support is mandatory for wireless LAN in the office Key challenges: throughput, quality of service, security/privacy

  32. Public Access [HotSpot] 􀂈 ISP provide decentralized internet (and intranet) access 􀂈 Hot spot coverage 􀂈 High numbers of users (e.g. up to 50 users at 80m2) 􀂈 Dramatic variation of maximum transmission bit rate during hand-off (vertical & horizontal) 􀃆 Highly flexible MAC required 􀂈 Differing service requirements Key challenges: flexible high speed MAC, trade range vs. rate

  33. Public Access – Trains and Highways • Internet access in trains and cars • Hot spot coverage along railway tracks and highways • Access points in 100-300m distance • LOS conditions • High Doppler shift, low Doppler spread • “Standard” hot spot solutions partly applicable

  34. Link Layer Options 􀂈 “Conventional” Radio Communications =>WG5 White Paper on MIMO-OFDM TDD Physical Layer 􀂈 Ultra Wideband =>WG5 White Paper on UWB: Technology and Future Perspectives 􀂈 Millimeter Wave Communications =>Upcoming WG5 WWRF Briefing 􀂈 Optical Communications =>WG5 White Paper on Optical Wireless Communications

  35. Main Challenges • User data rates up to 100 MBit/s, peak data rate ~1 GBit/s • Efficient and flexible high speed MAC with QoS • Auto-configuration, ad-hoc and multi-hop capabilities • Ease of integration in IP based backbone • Coexistence with other systems

  36. Technology Trends • Baseband (focus on “conventional” radio communications) • Spatial diversity and multiplexing techniques • Multi-carrier modulation • Turbo principle – iterative decoding, equalization, etc. • Adaptive modulation and coding • MAC • Avoid short data burst to minimize MAC overhead • Superposed signaling (separate high rate from low rate data) • QoS support • Cross-layer optimization • Implementation issues • PAPR reduction, baseband compensation for “Dirty RF”

  37. Technology trends: Baseband techniques • OFDM to efficiently equalize frequency selective channel • Enabler for high MAC granularity (OFDMA) • Preamble design – Guard interval vs. IOTA/OQAM • Implementation issues – PAPR, phase noise, etc. • MIMO to attain high spectral efficiency • Receiver processing – Linear, PIC, SIC, ML-like • Transmitter processing – Linear, THP, Lattice Precoding • Channel estimation – More pilots needed • Iterative processing to minimize SNR requirements • Turbo equalization, data aided channel estimation, etc. • Processing power vs. RF requirements trade-off

  38. Technology trends: MAC issues • Efficiency (long PHY bursts short MAC PDUs) • Fast ARQ, Hybrid ARQ • New metrics for Link Adaptation • Packet aggregation, superposed signaling • Multi-dimensional resource allocation (Time, Frequency, Space) • Flexibility, centralized vs. distributed scheduling • Coordinated on-demand resource allocations • Ensure high efficiency and low delay in high load regime • Distributed allocation mechanisms (ad-hoc capabilities) • Self-configuration • Topology & coordination management • Efficient routing schemes with good dynamic properties

  39. Technology trends: Cross-layer optimization Combined optimization throughout the network stack: • PHY aware scheduling & routing • Channel conditions need to be taken into account at higher layers • Multi user scheduling for throughput maximization (MIMO Multi User) • Quality of Service mechanisms • Resource allocation based on service level agreements • QoS aware error control

  40. Standardization • IEEE 802.11a (WLAN) • Data rates 54 MBit/s • OFDM, carrier at 5 GHz • PHY almost identical to ETSI/BRAN HiperLAN/2 • IEEE 802.11n (high throughput study group) • Data rates 108-320 MBit/s (100 MBit/s on MAC SAP @ 20 MHz BW) • MIMO-OFDM, carriers at 2.4, 5 GHz • IEEE 802.15 (WPAN) • Relevant subgroup: 802.15.3/3a (High rate, Alternative PHY) • PHY data rates up to ~ 500 MBit/s • Multi-band OFDM, DS-CDMA • Carriers at 3.5 – 10 GHz, ultra wide bands

  41. Gigabit Wireless Applications Using 60 GHz Radios

  42. Deployment • Smaller Range Medium Range Large Range

  43. Technology • License-free 60 GHz radios have unique characteristics that make them substantially different from traditional 2.4 GHz or 5 GHz license-free radios, as well as setting them apart from licensed-band millimeter-wave radios. The attributes of 60 GHz radios that arise from these characteristics include: · License-free deployment · Multi-gigabit operation · Ability to co-locate multiple radios on a single roof or mast · Immunity to interference · Security from signal interception · Ease of installation

  44. Factors • Rainfall Limitations. • Oxygen Absorption. • Narrow Beams Antennas. • License-Free Spectrum.

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