Opportunistic communication: A system view

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

The wireless medium is often called a fading channel: the pejorative adjective suggests that the intrinsic temporal and frequency variations are an impediment to reliable communication. While not untrue, the channel fluctuations are turned from foe to friend in some scenarios. A concrete situation is when the time scale of communication is much larger than that of the channel fluctuations: the so-called ergodic fading channel. In a pointto- point ergodic fading channel, the transmitter can make good use of the channel state information (CSI): by devoting more power to when the channel is good and less (or even none) when the channel is bad, the rate of reliable communication is improved. The improvement is significant when the operating signal-to-noise ratio (SNR) is small; this is a simple instance of opportunistic communication. Another important instance is in cellular communication: by scheduling user transmissions when their channel conditions are good, the system throughput is improved. This effect is called multiuser diversity and its role in cellular communication is the focus of this chapter. Multiuser diversity gain Consider the single antenna downlink flat fading channel with K users: where hk [m] m is the channel fading process of user k. There is an average power constraint of P on the transmit signal and wk [m] ∼ CN (0, N0) are i.i.d. in time m (for each user k = l, …, K).

Original languageEnglish (US)
Title of host publicationSpace-Time Wireless Systems
Subtitle of host publicationFrom Array Processing to MIMO Communications
PublisherCambridge University Press
Pages426-442
Number of pages17
Volume9780521851053
ISBN (Electronic)9780511616815
ISBN (Print)9780521851053
DOIs
StatePublished - Jan 1 2006

Fingerprint

Fading channels
Communication
Cellular radio systems
Channel state information
Transmitters
Signal to noise ratio
Scheduling
Throughput
Antennas

ASJC Scopus subject areas

  • Engineering(all)

Cite this

Viswanath, P. (2006). Opportunistic communication: A system view. In Space-Time Wireless Systems: From Array Processing to MIMO Communications (Vol. 9780521851053, pp. 426-442). Cambridge University Press. https://doi.org/10.1017/CBO9780511616815.022

Opportunistic communication : A system view. / Viswanath, Pramod.

Space-Time Wireless Systems: From Array Processing to MIMO Communications. Vol. 9780521851053 Cambridge University Press, 2006. p. 426-442.

Research output: Chapter in Book/Report/Conference proceedingChapter

Viswanath, P 2006, Opportunistic communication: A system view. in Space-Time Wireless Systems: From Array Processing to MIMO Communications. vol. 9780521851053, Cambridge University Press, pp. 426-442. https://doi.org/10.1017/CBO9780511616815.022
Viswanath P. Opportunistic communication: A system view. In Space-Time Wireless Systems: From Array Processing to MIMO Communications. Vol. 9780521851053. Cambridge University Press. 2006. p. 426-442 https://doi.org/10.1017/CBO9780511616815.022
Viswanath, Pramod. / Opportunistic communication : A system view. Space-Time Wireless Systems: From Array Processing to MIMO Communications. Vol. 9780521851053 Cambridge University Press, 2006. pp. 426-442
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