551 research outputs found
Achievable Outage Rates with Improved Decoding of Bicm Multiband Ofdm Under Channel Estimation Errors
We consider the decoding of bit interleaved coded modulation (BICM) applied
to multiband OFDM for practical scenarios where only a noisy (possibly very
bad) estimate of the channel is available at the receiver. First, a decoding
metric based on the channel it a posteriori probability density, conditioned on
the channel estimate is derived and used for decoding BICM multiband OFDM.
Then, we characterize the limits of reliable information rates in terms of the
maximal achievable outage rates associated to the proposed metric. We also
compare our results with the outage rates of a system using a theoretical
decoder. Our results are useful for designing a communication system where a
prescribed quality of service (QoS), in terms of achievable target rates with
small error probability, must be satisfied even in the presence of imperfect
channel estimation. Numerical results over both realistic UWB and theoretical
Rayleigh fading channels show that the proposed method provides significant
gain in terms of BER and outage rates compared to the classical mismatched
detector, without introducing any additional complexity
Symbol-Level Selective Full-Duplex Relaying with Power and Location Optimization
In this paper, a symbol-level selective transmission for full-duplex (FD)
relaying networks is proposed to mitigate error propagation effects and improve
system spectral efficiency. The idea is to allow the FD relay node to predict
the correctly decoded symbols of each frame, based on the generalized square
deviation method, and discard the erroneously decoded symbols, resulting in
fewer errors being forwarded to the destination node. Using the capability for
simultaneous transmission and reception at the FD relay node, our proposed
strategy can improve the transmission efficiency without extra cost of
signalling overhead. In addition, targeting on the derived expression for
outage probability, we compare it with half-duplex (HD) relaying case, and
provide the transmission power and relay location optimization strategy to
further enhance system performance. The results show that our proposed scheme
outperforms the classic relaying protocols, such as cyclic redundancy check
based selective decode-and-forward (S-DF) relaying and threshold based S-DF
relaying in terms of outage probability and bit-error-rate. Moreover, the
performances with optimal power allocation is better than that with equal power
allocation, especially when the FD relay node encounters strong
self-interference and/or it is close to the destination node.Comment: 34 pages (single-column), 14 figures, 2 tables, accepted pape
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