| 1. |
- Björnson, Emil, et al.
(författare)
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DISTRIBUTED MASSIVE MIMO IN CELLULAR NETWORKS: IMPACT OF IMPERFECT HARDWARE AND NUMBER OF OSCILLATORS
- 2015
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Ingår i: 2015 23rd European Signal Processing Conference. - : Institute of Electrical and Electronics Engineers (IEEE). - 2076-1465. - 9780992862633 ; , s. 2436-2440
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Konferensbidrag (refereegranskat)abstract
- Distributed massive multiple-input multiple-output (MIMO) combines the array gain of coherent MIMO processing with the proximity gains of distributed antenna setups. In this paper, we analyze how transceiver hardware impairments affect the downlink with maximum ratio transmission. We derive closed-form spectral efficiencies expressions and study their asymptotic behavior as the number of the antennas increases. We prove a scaling law on the hardware quality, which reveals that massive MIMO is resilient to additive distortions, while multiplicative phase noise is a limiting factor. It is also better to have separate oscillators at each antenna than one per BS.
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| 2. |
- Celebi, Hasan Basri, et al.
(författare)
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A Multi-Objective Optimization Framework for URLLC With Decoding Complexity Constraints
- 2022
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Ingår i: IEEE Transactions on Wireless Communications. - : Institute of Electrical and Electronics Engineers (IEEE). - 1536-1276 .- 1558-2248. ; 21:4, s. 2786-2798
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Tidskriftsartikel (refereegranskat)abstract
- Stringent constraints on both reliability and latency must be guaranteed in ultra-reliable low-latency communication (URLLC). To fulfill these constraints with computationally constrained receivers, such as low-budget IoT receivers, optimal transmission parameters need to be studied in detail. In this paper, we introduce a multi-objective optimization framework for the optimal design of URLLC in the presence of decoding complexity constraints. We consider transmission of short-blocklength codewords that are encoded with linear block encoders, transmitted over a binary-input AWGN channel, and finally decoded with order-statistics (OS) decoder. We investigate the optimal selection of a transmission rate and power pair, while satisfying the constraints. For this purpose, a multi-objective optimization problem (MOOP) is formulated. Based on the empirical model that accurately quantifies the trade-off between the performance of an OS decoder and its computational complexity, the MOOP is solved and the Pareto boundary is derived. In order to assess the overall performance among several Pareto-optimal transmission pairs, two scalarization methods are investigated. To exemplify the importance of the MOOP, a case study on a battery-powered communication system is provided. It is shown that, compared to the classical fixed rate-power transmissions, the MOOP provides the optimum usage of the battery and increases the energy efficiency of the communication system while maintaining the constraints.
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| 3. |
- Celebi, Hasan Basri, et al.
(författare)
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Low-latency communication with computational complexity constraints
- 2019
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Ingår i: Proceedings of the International Symposium on Wireless Communication Systems. - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 384-388
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Konferensbidrag (refereegranskat)abstract
- Low-latency communication is one of the most important application scenarios in next-generation wireless networks. Often in communication-theoretic studies latency is defined as the time required for the transmission of a packet over a channel. However, with very stringent latency requirements and complexity constrained receivers, the time required for the decoding of the packet cannot be ignored and must be included in the total latency analysis through accurate modeling. In this paper, we first present a way to calculate decoding time using per bit complexity metric and introduce an empirical model that accurately describes the trade-off between the decoding complexity versus the performance of state-of-the-art codes. By considering various communication parameters, we show that including the decoding time in latency analyses has a significant effect on the optimum selection of parameters.
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| 4. |
- Celebi, Hasan Basri, et al.
(författare)
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Training-Assisted Channel Estimation for Low-Complexity Squared-Envelope Receivers
- 2018
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Ingår i: IEEE Workshop on Signal Processing Advances in Wireless Communications, SPAWC. - : Institute of Electrical and Electronics Engineers Inc.. - 9781538635124 ; , s. 196-200
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Konferensbidrag (refereegranskat)abstract
- Squared-envelope receivers, also known as energy detectors, are, due to their simplified circuitry, low-cost and low-complexity receivers. Hence they are attractive implementation structures for future Internet-of-Things (IoT) applications. Even though there is considerable work on the wider research area of squared-envelope receivers, a comprehensive comparison and statistical characterization of training-assisted channel estimators for squared-envelope receivers appear to be absent from the literature. A detailed description of practical channel estimation schemes is necessary for the optimal training design of latency-constrained IoT applications. In this paper, various channel estimators are derived, their bias and variance are studied, and their performance is numerically compared against the Cramer-Rao lower bound.
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| 5. |
- Celebi, Hasan Basri, et al.
(författare)
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Wireless communication for the industrial IoT
- 2020
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Ingår i: Industrial IoT: Challenges, Design Principles, Applications, and Security. - Cham : Springer International Publishing. ; , s. 57-94
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The emergence of the Internet-of-Things (IoT), which will enable billions of devices to seamlessly connect with each other and to the Internet, aims to enhance the quality of daily life in diverse fields. Today, even though an abundance of IoT applications already exists, the growth of IoT is expected to accelerate in the foreseeable future. IoT applications are mainly divided into two categories: (1) consumer IoT and (2) industrial IoT (IIoT). The IIoT consists of interconnected sensors, machinery, and other “things” that are used in various fields of industrial applications. Throughout this chapter, the main focus is on wireless communication for IIoT applications and therefore the major challenges in designing a suitable wireless communication solution for IIoT applications are initially discussed. A comprehensive overview of the state-of-the-art wireless communication standards, which are suitable for IIoT applications, is presented and representative comparisons on some of the most common industrial wireless communication technologies including 5G, the next generation of the wireless technologies, are provided. Next, we focus on one of the most significant technologies for 5G systems, namely the ultra-reliable low-latency communication (URLLC), which is highly relevant for mission-critical IIoT applications. We list the challenges of URLLC and study the theoretical limits on the transmission of short packets. In these information theoretic works, latency is mostly computed as the total transmission time of a single packet. However, decoding a encoded packet is a computationally demanding operation and when we analyse complexity-constrained receivers, such as low complexity IIoT receivers, the time duration that is needed for decoding should also be taken into account in latency analysis. Finally, by including the decoding duration, we present the trade-offs in low-latency communication for receivers with computational complexity constraints.
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| 6. |
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| 7. |
- Pitarokoilis, Antonios, et al.
(författare)
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A Non-Asymptotic Converse on the Maximal Coding Rate of Fading Channels with Partial CSIR
- 2020
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Ingår i: 2020 IEEE International Conference on Communications, (ICC). - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- The problem of communication in Rayleigh fading channels with estimated channel state information at the receiver (CSIR) is investigated. Based on a related hypothesis testing problem in the Neyman-Pearson formulation, a non-asymptoticin the codeword block-length-converse on the maximal coding rate is derived. The bound summarizes succinctly the effect of various system parameters that include the length of channel coherence interval, the length of the training and data intervals and the power allocated to training and data transmission. The bound is also studied in the asymptotic-in the codeword block-length-regime and a particularly simple, non-trivial upper bound on the ergodic capacity of Raleigh fading channels with estimated CSIR is obtained. Finally, a second-order asymptotic expansion of the non-asymptotic converse is provided, which can be very useful in the study of latency-constrained communication systems.
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| 8. |
- Pitarokoilis, Antonios, et al.
(författare)
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Achievable Rates of ZF Receivers in Massive MIMO with Phase Noise Impairments
- 2013
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Ingår i: 2013 ASILOMAR CONFERENCE ON SIGNALS, SYSTEMS AND COMPUTERS. - 9781479923908 ; , s. 1004-1008
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Konferensbidrag (refereegranskat)abstract
- The effect of oscillator phase noise on the sum-rate performance of large multi-user multiple-input multiple-output (MU-MIMO) systems, termed as Massive MIMO, is studied. A Rayleigh fading MU-MIMO uplink channel is considered, where channel state information (CSI) is acquired via training. The base station (BS), which is equipped with an excess of antenna elements, M, uses the channel estimate to perform zero-forcing (ZF) detection. A lower bound on the sum-rate performance is derived. It is shown that the proposed receiver structure exhibits an O() array power gain. Additionally, the proposed receiver is compared with earlier studies that employ maximum ratio combining and it is shown that it can provide significant sum-rate performance gains at the medium and high signal-to-noise-ratio (SNR) regime. Further, the expression of the achievable sum rate provides new insights on the effect of various parameters on the overall system performance.
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| 9. |
- Pitarokoilis, Antonios, et al.
(författare)
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Effect of Oscillator Phase Noise on Uplink Performance of Large MU-MIMO Systems
- 2012
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Ingår i: Proceedings of the 50th Annual Allerton Conference on Communication, Control, and Computing. - : IEEE. - 9781467345378 ; , s. 1190-1197
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Konferensbidrag (refereegranskat)abstract
- The effect of oscillator phase noise on the sumrate performance of a frequency selective multi-user multipleinputmultiple-output (MU-MIMO) uplink channel is studiedunder imperfect channel state information. A maximum ratiocombining detection strategy is employed by the base station(BS) (having a large antenna array of M elements), and ananalytical expression of a lower bound on the sum capacity ofthe system is derived. It is shown that an array power gainof O(pM) is achievable. It is also observed that phase noiseeffectively limits the fraction of the time used for informationtransmission and the number of users in the system. Finally itis concluded that, phase noise degrades the performance butdoes not eliminate the fundamental gains of a Large ScaleAntenna System (LSAS), i.e., power efficiency and high sumrate performance with low complexity receiver processing.
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| 10. |
- Pitarokoilis, Antonios, et al.
(författare)
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Frequency Diversity versus Channel Training in Latency-Constrained Massive MIMO
- 2019
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Ingår i: 2019 IEEE 20th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC). - : Institute of Electrical and Electronics Engineers (IEEE).
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Konferensbidrag (refereegranskat)abstract
- The effect of correlation between neighboring resource blocks (RBs) in the outage probability performance of OFDM-based Massive MIMO systems is investigated. An upper bound on the outage probability, which is the relevant performance metric for latency-constrained communication, of two operations that exploit this correlation structure is derived and compared with the base scenario of orthogonal communication, where the correlation is ignored. It is observed that substantial outage probability improvement can be reaped already when moderate correlation is present. Closed-form upper and lower bounds on the investigated outage probability are derived. The bounds are shown to be tight for a wide range of system parameters and can be used to draw insights on the optimal design of latency-constrained Massive MIMO systems.
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