Transmit diversity over quasi-static fading channels using multiple antennas and random signal mapping

Li, Y.; Georghiades, C.N.

doi:10.1109/icc.2000.853699

Cited by 10 publications

(22 citation statements)

References 19 publications

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“…5 are presented when ρ k,l = 0.25 for k = l. In this case, since the crosscorrelation is high, the MAI is very effective and very high error probabilities are encountered. Also, it can be shown that the conditions in (28) and those in (30)- (31) are not satisfied for this scenario. In Fig.…”

Section: Performance Evaluationmentioning

confidence: 96%

“…Proposition 3: Consider sign detectors and symmetric signaling, and assume that there exist no signal amplitudes that satisfy (28). In addition, define s * as a joint signal constellation that minimizes the sum of the average error probabilities of the users.…”

Section: Achieved If There Exist Signal Amplitudes Such Thatmentioning

confidence: 99%

“…In fact, it can be shown that the assumptions in the proposition are satisfied in this scenario. Namely, there exist no signal amplitudes that satisfy (28), and the conditions in (30)- (31) are satisfied, for example, when all S (1) k 's are 1.2 except for one of them, which is equal to 0.8.…”

Section: Performance Evaluationmentioning

confidence: 99%

“…Although a form of constellation randomization is performed in [26], [27], they are different from the current work since a (pseudo)random rotation of the signal constellation is proposed for a single user system in those studies, whereas we obtain optimal randomization of signal constellations for a multiuser system in this work. In addition, the studies in [28]- [31] consider random signal mapping, random rotations, or time-varying phase shifts to transmitted signals in order to achieve diversity.…”

mentioning

confidence: 99%

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Optimal Randomization of Signal Constellations on the Downlink of a Multiuser DS-CDMA System

Tutay

Gezici

Arıkan

2013

IEEE Trans. Wireless Commun.

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Abstract-In this study, the jointly optimal power control with signal constellation randomization is proposed for the downlink of a multiuser communications system. Unlike a conventional system in which a fixed signal constellation is employed for all the bits of a user (for given channel conditions and noise power), power control with signal constellation randomization involves randomization/time-sharing among different signal constellations for each user. A formulation is obtained for the problem of optimal power control with signal constellation randomization, and it is shown that the optimal solution can be represented by a randomization among (K + 1) or fewer distinct signal constellations for each user, where K denotes the number of users. In addition to the original nonconvex formulation, an approximate solution based on convex relaxation is derived. Then, detailed performance analysis is presented when the receivers employ symmetric signaling and sign detectors. Specifically, the maximum asymptotical improvement ratio is shown to be equal to the number of users, and the conditions under which the maximum and minimum asymptotical improvement ratios are achieved are derived. Numerical examples are presented to investigate the theoretical results, and to illustrate performance improvements achieved via the proposed approach.

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Section: Performance Evaluationmentioning

confidence: 96%

Section: Achieved If There Exist Signal Amplitudes Such Thatmentioning

confidence: 99%

Section: Performance Evaluationmentioning

confidence: 99%

mentioning

confidence: 99%

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Optimal Randomization of Signal Constellations on the Downlink of a Multiuser DS-CDMA System

Tutay

Gezici

Arıkan

2013

IEEE Trans. Wireless Commun.

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“…Reference [15] proposed to use a random signal mapping to introduce diversity (this work differs from ours in that we consider performance improvement of coded spatial multiplexing, rather than ways of achieving transmit diversity). There are also techniques called "phase sweeping" [16], [17] which achieve a diversity effect by introducing a time-varying phase-shift to the transmitted signal.…”

Section: Contributions Of the Paper And Related Workmentioning

confidence: 99%

Constellation randomization (CoRa) for outage performance improvement on MIMO channels

Larsson

IEEE Global Telecommunications Conference, 2004. GLOBECOM '04.

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Abstract-This paper studies a new concept, "constellation randomization" (CoRa), for performance improvement of transmission over quasi-static (block fading) multidimensional ("MIMO") channels with small signal constellations. The motivation behind CoRa is to reduce some of the mutual information penalty associated with the use of a finite input alphabet for signalling on a static, possibly ill-conditioned, channel. We show, both via information-theoretic considerations, and via MonteCarlo simulation of the frame-error-rate (FER) of a coded system, that CoRa can offer a lower outage probability than a conventional spatial multiplexing system that uses a fixed signal constellation. In our examples the improvement offered by CoRa is comparable to that offered by linear (complex-field) precoding. This is interesting, because the performance gain of CoRa comes at virtually no computational expense.

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Stochastic signaling in the presence of channel state information uncertainty

Goken

Gezici

Arıkan

2013

Digital Signal Processing

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In this paper, stochastic signaling is studied for power-constrained scalar valued binary communications systems in the presence of uncertainties in channel state information (CSI). First, stochastic signaling based on the available imperfect channel coefficient at the transmitter is analyzed, and it is shown that optimal signals can be represented by a randomization between at most two distinct signal levels for each symbol. Then, performance of stochastic signaling and conventional deterministic signaling is compared for this scenario, and sufficient conditions are derived for improvability and nonimprovability of deterministic signaling via stochastic signaling in the presence of CSI uncertainty. Furthermore, under CSI uncertainty, two different stochastic signaling strategies, namely, robust stochastic signaling and stochastic signaling with averaging, are proposed. For the robust stochastic signaling problem, sufficient conditions are derived for reducing the problem to a simpler form. It is shown that the optimal signal for each symbol can be expressed as a randomization between at most two distinct signal values for stochastic signaling with averaging, as well as for robust stochastic signaling under certain conditions. Finally, two numerical examples are presented to explore the theoretical results. © 2012 Elsevier Inc

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Transmit diversity over quasi-static fading channels using multiple antennas and random signal mapping

Cited by 10 publications

References 19 publications

Optimal Randomization of Signal Constellations on the Downlink of a Multiuser DS-CDMA System

Optimal Randomization of Signal Constellations on the Downlink of a Multiuser DS-CDMA System

Constellation randomization (CoRa) for outage performance improvement on MIMO channels

Stochastic signaling in the presence of channel state information uncertainty

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