ECS Wireless oundations 5.Capacity of Wireless Channels Fundamentals of Wireless Communication,Tse&Viswanath
5: Capacity of Wireless Channels Fundamentals of Wireless Communication, Tse&Viswanath 1 5. Capacity of Wireless Channels
5:Capacity of Wireless Channels EECS Vireless oundations Information Theory So far we have only looked at specific communication schemes. Information theory provides a fundamental limit to(coded) performance. It succinctly identifies the impact of channel resources on performance as well as suggests new and cool ways to communicate over the wireless channel. It provides the basis for the modern development of wireless communication. Fundamentals of Wireless Communication,Tse&Viswanath 2
5: Capacity of Wireless Channels Fundamentals of Wireless Communication, Tse&Viswanath 2 Information Theory • So far we have only looked at specific communication schemes. • Information theory provides a fundamental limit to (coded) performance. • It succinctly identifies the impact of channel resources on performance as well as suggests new and cool ways to communicate over the wireless channel. • It provides the basis for the modern development of wireless communication
5:Capacity of Wireless Channels EECS Wireless Foundations Historical Perspective Gugliemo Marconi Claude Shannon 1901 1948 Wireless communication .Information theory says every has been around since channel has a capacity. 1900's. Many recent advances based Ingenious but somewhat on understanding wireless adhoc design techniques channel capacity. New points of views arise. Fundamentals of Wireless Communication,Tse&Viswanath 3
5: Capacity of Wireless Channels Fundamentals of Wireless Communication, Tse&Viswanath 3 Historical Perspective • Wireless communication has been around since 1900’s. • Ingenious but somewhat adhoc design techniques Gugliemo Marconi Claude Shannon •Information theory says every channel has a capacity. • Many recent advances based on understanding wireless channel capacity. New points of views arise. 1901 1948
5:Capacity of Wireless Channels EECS Wireless oundations Multipath Fading:A Modern View LLL7777177777 6dB Classical view:fading channels are unreliable Modern view:multipath fading can be exploited to increase spectral efficiency. Fundamentals of Wireless Communication,Tse&Viswanath 4
5: Capacity of Wireless Channels Fundamentals of Wireless Communication, Tse&Viswanath 4 Multipath Fading: A Modern View Classical view: fading channels are unreliable Modern view: multipath fading can be exploited to increase spectral efficiency. 16dB
5:Capacity of Wireless Channels Vireless F oundations Capacity of AWGN Channel Capacity of AWGN channel Cawgn log(1+SNR) bits/s/HZ =Wlog(1+SNR)bits/s If average transmit power constraint is P watts and noise psd is No watts/Hz, bits/s. Fundamentals of Wireless Communication,Tse&Viswanath 5
5: Capacity of Wireless Channels Fundamentals of Wireless Communication, Tse&Viswanath 5 Capacity of AWGN Channel Capacity of AWGN channel If average transmit power constraint is watts and noise psd is watts/Hz