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Bandwidth expansion

About: Bandwidth expansion is a research topic. Over the lifetime, 530 publications have been published within this topic receiving 6778 citations.


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Proceedings ArticleDOI
23 May 1993
TL;DR: A system is proposed and analyzed, which uses several transmit antennas to achieve diversity in a flat fading mobile radio environment, and simulation results confirm the expected gain.
Abstract: A system is proposed and analyzed, which uses several transmit antennas to achieve diversity in a flat fading mobile radio environment. The signals at different antennas carry the same digital information, but have different modulation parameters (modulation diversity). In contrast to other proposals, no bandwidth expansion is required. Modulation diversity for quadrature amplitude modulation (QAM) type modulation is achieved by using different partial response type base pulses. Simulation results confirm the expected gain. >

489 citations

Journal ArticleDOI
TL;DR: A novel iterative receiver is proposed to estimate and cancel the distortion caused by clipping noise and it is shown by simulation that for an IEEE 802.11a typical scenario the system performance can be restored to within 1 dB of the nonclipped case with only moderate complexity increase and with no bandwidth expansion.
Abstract: Clipping is an efficient and simple method to reduce the peak-to-average power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) signals. However, clipping causes distortion and out-of-band radiation. In this letter, a novel iterative receiver is proposed to estimate and cancel the distortion caused by clipping noise. The proposed method is applied to clipped and filtered OFDM signals. It is shown by simulation that for an IEEE 802.11a typical scenario the system performance can be restored to within 1 dB of the nonclipped case with only moderate complexity increase and with no bandwidth expansion.

247 citations

Journal ArticleDOI
TL;DR: Computer simulation results indicate that BICM-ID, with a few iterations, significantly outperforms conventional trellis coded modulation and is therefore another promising technique to achieve large coding gain without bandwidth expansion.
Abstract: A new iterative decoding (ID) scheme is suggested for bit-interleaved coded modulation (BICM). The bit-metric generation at the demodulator is optimised with the soft-output feedback from the convolutional decoder. Computer simulation results indicate that BICM-ID, with a few iterations, significantly outperforms conventional trellis coded modulation and is therefore another promising technique to achieve large coding gain without bandwidth expansion.

223 citations

Journal ArticleDOI
TL;DR: It is shown how a system with a partial feedback, returning from the bad receiver to the transmitter and to the good receiver, achieves a distortion pair that lies on the outer bound derived here.
Abstract: We consider the problem of broadcasting a single Gaussian source to two listeners over a Gaussian broadcast channel, with rho channel uses per source sample, where rho>1. A distortion pair (D1 ,D2) is said to be achievable if one can simultaneously achieve a mean-squared error (MSE) D1 at receiver 1 and D2 at receiver 2. The main result of this correspondence is an outer bound for the set of all achievable distortion pairs. That is, we find necessary conditions under which (D1,D2) is achievable. We then apply this result to the problem of point-to-point transmission over a Gaussian channel with unknown signal-to-noise ratio (SNR) and rho>1. We show that if a system must be optimal at a certain SNRmin, then, asymptotically, the system distortion cannot decay faster than O(1/SNR). As for achievability, we show that a previously reported scheme, due to Mittal and Phamdo (2002), is optimal at high SNR. We introduce two new schemes for broadcasting with bandwidth expansion, combining digital and analog transmissions. We finally show how a system with a partial feedback, returning from the bad receiver to the transmitter and to the good receiver, achieves a distortion pair that lies on the outer bound derived here

181 citations

Proceedings ArticleDOI
05 Dec 1999
TL;DR: A truly coherent receiver based on the Viterbi algorithm is proposed and verified, which is optimal in the sense of per-survivor processing and a generic low-cost receiver structure based on reduced-state sequence estimation is suggested.
Abstract: For the purpose of various synchronization tasks (including carrier phase, time, frequency, and frame synchronization), one may add a known pilot sequence, typically a pseudo-noise sequence, to the unknown data sequence. This approach is known as a spread-spectrum pilot technique or as a superimposed pilot sequence technique. In this paper, we apply the superimposed pilot sequence technique for the purpose of channel estimation (CE). We propose and verify a truly coherent receiver based on the Viterbi algorithm, which is optimal in the sense of per-survivor processing. We also suggest a generic low-cost receiver structure based on reduced-state sequence estimation. Among the distinct advantages compared to conventional pilot-symbol-assisted CE are (i) a lack of bandwidth expansion and (ii) a significantly improved performance in fast fading environments. The proposed Viterbi receiver may also be used as an alternative receiver for pilot-symbol-assisted CE.

169 citations

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20218
202015
201919
201818
201720
201614