ECS Wireless F oundations 6.Opportunistic Communication and Multiuser Diversity Fundamentals of Wireless Communication,Tse&Viswanath
6: Opportunistic Communication and Multiuser Diversity Fundamentals of Wireless Communication, Tse&Viswanath 1 6. Opportunistic Communication and Multiuser Diversity
6:Opportunistic Communication and Multiuser EECS Diversity Wireless oundations Fundamental Feature of Wireless Channels: Time Variation Channel Strength Time time-varying channel ·multipath fading large-scale channel variations time-varying interference Fundamentals of Wireless Communication,Tse&Viswanath 2
6: Opportunistic Communication and Multiuser Diversity Fundamentals of Wireless Communication, Tse&Viswanath 2 Fundamental Feature of Wireless Channels: Time Variation • multipath fading • large-scale channel variations • time-varying interference
6:Opportunistic Communication and Multiuser ECS Diversity Wireless F oundations Traditional Approach to Wireless System Design Channel Channel Strength Strength Time Time time-varying channel constant channel Compensates for channel fluctuations. Fundamentals of Wireless Communication,Tse&Viswanath 3
6: Opportunistic Communication and Multiuser Diversity Fundamentals of Wireless Communication, Tse&Viswanath 3 Traditional Approach to Wireless System Design Compensates for channel fluctuations
6:Opportunistic Communication and Multiuser ECS Diversity vireless oundations Example:CDMA Systems Two main types of compensating mechanisms: 1.Channel diversity: frequency diversity via Rake combining time diversity via interleaving and coding macro-diversity via soft handoff transmit/receive antenna diversity 2.Interference management: 一 power control interference averaging Fundamentals of Wireless Communication,Tse&Viswanath 4
6: Opportunistic Communication and Multiuser Diversity Fundamentals of Wireless Communication, Tse&Viswanath 4 Example: CDMA Systems Two main types of compensating mechanisms: 1. Channel diversity: – frequency diversity via Rake combining – time diversity via interleaving and coding – macro-diversity via soft handoff – transmit/receive antenna diversity 2. Interference management: – power control – interference averaging
6:Opportunistic Communication and Multiuser EECS Diversity Wireless F oundations What Drives this Approach? Channel Channel Strength Strength Time Time time-varying channel constant channel Main application is voice,with very tight latency requirements. Needs a consistent channel. Fundamentals of Wireless Communication,Tse&Viswanath 5
6: Opportunistic Communication and Multiuser Diversity Fundamentals of Wireless Communication, Tse&Viswanath 5 What Drives this Approach? Main application is voice, with very tight latency requirements. Needs a consistent channel