Abstract
This paper finds the capacity of single-user discrete-time channels subject to both frequency-selective and time-selective fading, where the channel output is observed in additive Gaussian noise. A coherent model is assumed where the fading coefficients are known at the receiver. Capacity depends on the first-order distributions of the fading processes in frequency and in time, which are assumed to be independent of each other, and a simple formula is given when one of the processes is independent identically distributed (i.i.d.) and the other one is sufficiently mixing. When the frequency-selective fading coefficients are known also to the transmitter, we show that the optimum normalized power spectral density is the waterfilling power allocation for a reduced signal-to-noise ratio (SNR), where the gap to the actual SNR depends on the fading distributions. Asymptotic expressions for high/low SNR and easily computable bounds on capacity are also provided.
Original language | English (US) |
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Article number | 5429107 |
Pages (from-to) | 1187-1215 |
Number of pages | 29 |
Journal | IEEE Transactions on Information Theory |
Volume | 56 |
Issue number | 3 |
DOIs | |
State | Published - Mar 2010 |
All Science Journal Classification (ASJC) codes
- Information Systems
- Computer Science Applications
- Library and Information Sciences
Keywords
- Additive Gaussian noise
- Channel capacity
- Coherent communications
- Frequency-flat fading
- Frequency-selective Fading
- Orthogonal frequency-division multiplexing (OFDM)
- Random matrices
- Waterfilling