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- Li, A., et al.
(författare)
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A Tutorial on Interference Exploitation via Symbol-Level Precoding : Overview, State-of-the-Art and Future Directions
- 2020
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Ingår i: IEEE Communications Surveys and Tutorials. - : Institute of Electrical and Electronics Engineers (IEEE). - 1553-877X. ; 22:2, s. 796-839
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Tidskriftsartikel (refereegranskat)abstract
- Interference is traditionally viewed as a performance limiting factor in wireless communication systems, which is to be minimized or mitigated. Nevertheless, a recent line of work has shown that by manipulating the interfering signals such that they add up constructively at the receiver side, known interference can be made beneficial and further improve the system performance in a variety of wireless scenarios, achieved by symbol-level precoding (SLP). This paper aims to provide a tutorial on interference exploitation techniques from the perspective of precoding design in a multi-antenna wireless communication system, by beginning with the classification of constructive interference (CI) and destructive interference (DI). The definition for CI is presented and the corresponding mathematical characterization is formulated for popular modulation types, based on which optimization-based precoding techniques are discussed. In addition, the extension of CI precoding to other application scenarios as well as for hardware efficiency is also described. Proof-of-concept testbeds are demonstrated for the potential practical implementation of CI precoding, and finally a list of open problems and practical challenges are presented to inspire and motivate further research directions in this area.
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| 2. |
- Politis, C., et al.
(författare)
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Simultaneous Sensing and Transmission for Cognitive Radios With Imperfect Signal Cancellation
- 2017
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Ingår i: IEEE Transactions on Wireless Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1276 .- 1558-2248. ; 16:9, s. 5599-5615
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Tidskriftsartikel (refereegranskat)abstract
- In conventional cognitive radio systems, the secondary user employs a “listen-before-talk” paradigm, where it senses if the primary user is active or idle, before it decides to access the licensed spectrum. However, this method faces challenges, with the most important one being the reduction of the secondary user's throughput, as no data transmission takes place during the sensing period. In this context, the idea of simultaneous spectrum sensing and data transmission is proposed. This paper studies a system model where this concept is obtained through the collaboration of the secondary transmitter with the secondary receiver. First, the secondary receiver decodes the signal from the secondary transmitter, removes it from the total received signal, and then carries out spectrum sensing in the remaining signal in order to determine the presence/absence of the primary user. Different from the existing literature, this paper considers the imperfect signal cancellation, evaluating how the decoding errors affect the sensing reliability, and derives the analytical expressions for the probability of false alarm. Finally, numerical results are presented illustrating the accuracy of the proposed analysis.
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| 3. |
- 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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