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BEYOND OFDM A Systems Approach to Non-Line-of-Sight Fixed Wireless Rajeev Krishnamoorthy Broadband World Wireless Forum, San Francisco, CA February 19, 2001
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BEYOND OFDM - A Systems Approach to NLOS Fixed Wireless Rajeev Krishnamoorthy, Senior Engineering Director, Iospan Wireless / Slide 2 Broadband World Wireless Forum - San Francisco, CA - February 19, 2001 Broadband Market Requirements A Mass-Deployable system with a price point that will compete favorably to DSL and Cable: Low Capital Costs for Installed CPE & Infrastructure DSL/Cable-like QoS/Availability Easy Management/Provisioning These features require: True Non-Line-of-Sight Coverage Multi-cell with largest possible radius (6-miles or greater) and superior frequency reuse (scalable) Consumer installable CPE Can re-use existing cellular sites Minimum of 90% service coverage (homes passed)
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BEYOND OFDM - A Systems Approach to NLOS Fixed Wireless Rajeev Krishnamoorthy, Senior Engineering Director, Iospan Wireless / Slide 3 Broadband World Wireless Forum - San Francisco, CA - February 19, 2001 Fading Frequency Selective -- OFDM Space Selective -- MIMO + MAC Time Selective -- Link Adaptation + RLP Channel Impairments in Multi-Cell Co-channel Interference -15 -10 -5 0 5 10 time frequency -15 -10 -5 0 5 10 space C I
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BEYOND OFDM - A Systems Approach to NLOS Fixed Wireless Rajeev Krishnamoorthy, Senior Engineering Director, Iospan Wireless / Slide 4 Broadband World Wireless Forum - San Francisco, CA - February 19, 2001 Physical Layer Characteristics Multicarrier (OFDM) Modulation Important Foundation, but OFDM ALONE IS NOT ENOUGH TO ACHIEVE NLOS! MIMO (Multiple Input, Multiple Output) – Dynamic Per-user Spatial Processing Techniques Antenna Diversity Techniques to Increase Cell Size and Provide Complete Service Coverage Spatial Multiplexing: Increased Bit Rate to Users Aggressive Spectrum Reuse due to Interference Cancellation Dynamic Per-user Adaptive Modulation and Coding ( Link Adaptation) Delivers Optimal System Capacity by: Exploiting good conditions to increase user data rates Accommodating poor air-link conditions Done in conjunction with QoS Requirement & MAC Scheduling
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BEYOND OFDM - A Systems Approach to NLOS Fixed Wireless Rajeev Krishnamoorthy, Senior Engineering Director, Iospan Wireless / Slide 5 Broadband World Wireless Forum - San Francisco, CA - February 19, 2001 MAC Characteristics Differentiated Grades of Service & Quality of Service Reservation Schemes for Low Delay Jitter Services Dynamic Bandwidth Allocation & Scheduling for Bursty Data Fragmentation & Reassembly and Link-Layer Retransmission Increases Link Integrity and Improves TCP Performance Better Frequency Reuse Support for Unique PHY Modes of Operation Spatial Multiplexing and Transmit Diversity Adaptive Modulation and Coding Power Control Uplink & Downlink Transmission Scheduling Support for multiple Service Flows (distinct QoS) on each link Service Flow Attributes - Class of Service, Bandwidth, Loss, Latency Other Important Functions Admission Control, Link Initialization & Maintenance, Authentication & Security, etc.
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BEYOND OFDM - A Systems Approach to NLOS Fixed Wireless Rajeev Krishnamoorthy, Senior Engineering Director, Iospan Wireless / Slide 6 Broadband World Wireless Forum - San Francisco, CA - February 19, 2001 Fundamental System Design Requirements Low-cost RF enabled by digital pre-distortion, increased phase noise tolerance, carrier tracking loops, dynamic link adaptation, etc. Low-cost mechanical design of CPE by monitoring heat dissipation, antenna design, etc. QoS jointly guaranteed by the MAC and dynamic link adaptation High throughput by adaptive techniques, and by ensuring TCP behavior is matched to MAC and Radio Link Protocol Link optimization by matching QoS (error rate and latency) with the scheduling, ARQ, adaptive modulation, coding, and diversity Low required SINR (modem set-point) results in greater coverage, higher capacity, lower PA cost, and aggressive frequency reuse A high-performance and low-cost system requires an integrated design encompassing Antennas, RF, PHY, MAC, mechanicals, the network layer, and applications
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Supporting Slides
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BEYOND OFDM - A Systems Approach to NLOS Fixed Wireless Rajeev Krishnamoorthy, Senior Engineering Director, Iospan Wireless / Slide 8 Broadband World Wireless Forum - San Francisco, CA - February 19, 2001 Diversity using antennas Demonstrating Performance SISO 1 1SIMO 1 2MIMO 2 3 Tx Rx Tx Rx Tx Rx Trials Early Deployment Mass Deployment
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BEYOND OFDM - A Systems Approach to NLOS Fixed Wireless Rajeev Krishnamoorthy, Senior Engineering Director, Iospan Wireless / Slide 9 Broadband World Wireless Forum - San Francisco, CA - February 19, 2001 Features & Benefits of Iospan Approach
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BEYOND OFDM - A Systems Approach to NLOS Fixed Wireless Rajeev Krishnamoorthy, Senior Engineering Director, Iospan Wireless / Slide 10 Broadband World Wireless Forum - San Francisco, CA - February 19, 2001 The Iospan Advantage
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