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- Alodeh, M., et al.
(författare)
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Symbol-level and multicast precoding for multiuser multiantenna downlink : A state-of-the-art, classification, and challenges
- 2018
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Ingår i: IEEE Communications Surveys and Tutorials. - : Institute of Electrical and Electronics Engineers (IEEE). - 1553-877X. ; 20:3, s. 1733-1757
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Tidskriftsartikel (refereegranskat)abstract
- Precoding has been conventionally considered as an effective means of mitigating or exploiting the interference in the multiantenna downlink channel, where multiple users are simultaneously served with independent information over the same channel resources. The early works in this area were focused on transmitting an individual information stream to each user by constructing weighted linear combinations of symbol blocks (codewords). However, more recent works have moved beyond this traditional view by: 1) transmitting distinct data streams to groups of users and 2) applying precoding on a symbol-per-symbol basis. In this context, the current survey presents a unified view and classification of precoding techniques with respect to two main axes: 1) the switching rate of the precoding weights, leading to the classes of block-level and symbol-level precoding and 2) the number of users that each stream is addressed to, hence unicast, multicast, and broadcast precoding. Furthermore, the classified techniques are compared through representative numerical results to demonstrate their relative performance and uncover fundamental insights. Finally, a list of open theoretical problems and practical challenges are presented to inspire further research in this area1.1The concepts of precoding and beamforming are used interchangeably throughout this paper.
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| 2. |
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| 3. |
- Spano, D., et al.
(författare)
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Faster-Than-Nyquist Signaling Through Spatio-Temporal Symbol-Level Precoding for the Multiuser MISO Downlink Channel
- 2018
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Ingår i: IEEE Transactions on Wireless Communications. - 1536-1276 .- 1558-2248. ; 17:9, s. 5915-5928
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Tidskriftsartikel (refereegranskat)abstract
- This paper deals with the problem of the interference between multiple co-channel transmissions in the downlink of a multi-antenna wireless system. In this framework, symbol-level precoding (SLP) is a promising technique which is able to constructively exploit the multi-user interference and to transform it into useful power at the receiver side. While previous works on SLP were focused on exploiting the multi-user interference, in this paper, we extend this concept by jointly handling the interference both in the spatial dimension (multi-user interference) and in the temporal dimension (inter-symbol interference). Accordingly, we propose a novel precoding method, referred to as spatio-temporal SLP. In this new precoding paradigm, fasterthan-Nyquist (FTN) signaling can be applied over multi-user MISO systems, and the inter-symbol interference can be tackled at the transmitter side, without additional complexity for the user terminals. While applying FTN signaling, the proposed optimization strategies perform a sum power minimization with quality-of-service constraints. Numerical results are presented in a comparative fashion to show the effectiveness of the proposed techniques, which outperform the state-of-the-art SLP schemes in terms of symbol error rate, effective rate, and energy efficiency.
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| 5. |
- Spano, D., et al.
(författare)
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Symbol-Level Precoding for the Nonlinear Multiuser MISO Downlink Channel
- 2018
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Ingår i: IEEE Transactions on Signal Processing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1053-587X .- 1941-0476. ; 66:5, s. 1331-1345
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates the problem of the interference among multiple simultaneous transmissions in the downlink channel of a multiantenna wireless system. A symbol-level precoding scheme is considered, in order to exploit the multiuser interference and transform it into useful power at the receiver side, through a joint utilization of the data information and the channel state information. In this context, this paper presents novel strategies that exploit the potential of symbol-level precoding to control the per-antenna instantaneous transmit power. In particular, the power peaks among the transmitting antennas and the instantaneous power imbalances across the different transmitted streams are minimized. These objectives are particularly relevant with respect to the nonlinear amplitude and phase distortions induced by the per-antenna amplifiers, which are important sources of performance degradation in practical systems. More specifically, this paper proposes two different symbol-level precoding approaches. The first approach performs a weighted per-antenna power minimization, under quality-of-service constraints and under a lower bound constraint on the per-antenna transmit power. The second strategy performs a minimization of the spatial peak-to-average power ratio, evaluated among the transmitting antennas. Numerical results are presented in a comparative fashion to show the effectiveness of the proposed techniques, which outperform the state-of-the-art symbol-level precoding schemes in terms of spatial peak-to-average power ratio, spatial dynamic range, and symbol error rate over nonlinear channels.
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