| 1. |
- Biswas, Kamal, et al.
(författare)
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Efficient Techniques for Broadcast of System Information in mmWave Communication Systems
- 2018
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Ingår i: 2018 IEEE 19TH INTERNATIONAL WORKSHOP ON SIGNAL PROCESSING ADVANCES IN WIRELESS COMMUNICATIONS (SPAWC). - : IEEE. - 9781538635124 ; , s. 366-370
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Konferensbidrag (refereegranskat)abstract
- In this paper we consider Millimeter wave (mmWave) Massive MIMO systems where a large antenna array at the base station (BS) serves a few scheduled terminals. The high dimensional null space of the channel matrix to the scheduled terminals is utilized to broadcast system information to the non-scheduled terminals on the same time-frequency resource. Our analysis reveals the interesting result that with a sufficiently large antenna array this non-orthogonal broadcast strategy requires significantly less total transmit power when compared to the traditional orthogonal strategy where a fraction of the total resource is reserved for broadcast of system information.
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| 2. |
- Björnson, Emil, Professor, 1983-, et al.
(författare)
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Can Hardware Distortion Correlation be Neglected When Analyzing Uplink SE in Massive MIMO?
- 2018
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Ingår i: 2018 IEEE 19TH INTERNATIONAL WORKSHOP ON SIGNAL PROCESSING ADVANCES IN WIRELESS COMMUNICATIONS (SPAWC). - : IEEE. - 9781538635124 ; , s. 221-225
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Konferensbidrag (refereegranskat)abstract
- This paper analyzes how the distortion created by hardware impairments in a multiple-antenna base station affects the uplink spectral efficiency (SE), with focus on Massive MIMO. The distortion is correlated across the antennas, but has been often approximated as uncorrelated to facilitate (tractable) SE analysis. To determine when this approximation is accurate, basic properties of the distortion correlation are first uncovered. Then, we focus on third-order non-linearities and prove analytically and numerically that the correlation can be neglected in the SE analysis when there are many users. In i.i.d. Rayleigh fading with equal signal-to-noise ratios, this occurs when having five users.
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| 3. |
- 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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| 4. |
- Chandhar, Prabhu, 1986-, et al.
(författare)
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On the Zero-Forcing Receiver Performance for Massive MIMO Drone Communications
- 2018
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Ingår i: 2018 IEEE 19th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538635124 - 9781538635117 - 9781538635131 ; , s. 930-934
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Konferensbidrag (refereegranskat)abstract
- We study the uplink ergodic rate performance of the zero-forcing (ZF) receiver in a Massive multiple-input and multiple-output (MIMO) enabled drone communication system. Considering a 3D geometric model for line-of-sight (LoS) propagation, approximate but accurate analyses of lower and upper bounds on the uplink ergodic rate with estimated channel state information (CSI) are provided.
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| 5. |
- Gunnarsson, Sara, et al.
(författare)
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Channel Hardening in Massive MIMO-A Measurement Based Analysis
- 2018
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Ingår i: 2018 IEEE 19th International Workshop on Signal Processing Advances in Wireless Communications, SPAWC 2018. - 9781538635124 ; 2018-June
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Konferensbidrag (refereegranskat)abstract
- Wireless-controlled robots, cars and other critical applications are in need of technologies that offer high reliability and low latency. Massive MIMO, Multiple-Input Multiple-Output, is a key technology for the upcoming 5G systems and is one part of the solution to increase the reliability of wireless systems. More specifically, when increasing the number of base station antennas in a massive MIMO systems the channel variations decrease and the so-called channel hardening effect appears. This means that the variations of the channel gain in time and frequency decrease. In this paper, channel hardening in massive MIMO systems is assessed based on analysis of measurement data. For an indoor scenario, the channels are measured with a 128-port cylindrical array for nine single-antenna users. The analysis shows that in a real scenario a channel hardening of 3.2-4.6 dB, measured as a reduction of the standard deviation of the channel gain, can be expected depending on the amount of user interaction. Also, some practical implications and insights are presented.
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| 6. |
- Iwaki, Takuya, 1986-, et al.
(författare)
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LQG Control and Scheduling Co-Design for Wireless Sensor and Actuator Networks
- 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
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Konferensbidrag (refereegranskat)abstract
- This paper studies a co-design problem of control, scheduling and routing over a multi-hop sensor and actuator network subject to energy-saving consideration. Sensors are observing multiple independent linear systems and transmit their data to actuators in which controllers are co-located. We formulate an optimization problem, minimizing a linear combination of the averaged linear quadratic Gaussian control performance and the averaged transmission energy consumption. Optimal solutions are derived and their performance is illustrated in a numerical example. Algorithms to reconfigure routing between sensors and actuators in case of link disconnection are also provided.
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| 7. |
- Maros, Marie, et al.
(författare)
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DYNAMIC POWER ALLOCATION FOR SMART GRIDS VIA ADMM
- 2018
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Ingår i: 2018 IEEE 19TH INTERNATIONAL WORKSHOP ON SIGNAL PROCESSING ADVANCES IN WIRELESS COMMUNICATIONS (SPAWC). - : IEEE. - 9781538635124 ; , s. 416-420
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Konferensbidrag (refereegranskat)abstract
- Electric power distribution systems encounter fluctuations in supply due to renewable sources with high variability in generation capacity. It is therefore necessary to provide algorithms that are capable of dynamically finding approximate solutions. We propose two semi-distributed algorithms based on ADMM and discuss their advantages and disadvantages. One of the algorithms computes a feasible approximate of the optimal power allocation at each time instance. We require coordination between the nodes to guarantee feasibility of each of the iterates. We bound the distance from the approximate solutions to the optimal solution as a function of the variation in optimal power allocation, and we verify our results via experiments.
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| 8. |
- Mishra, Deepak, et al.
(författare)
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Optimizing Reciprocity-Based Backscattering with a Full-Duplex Antenna Array Reader
- 2018
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Ingår i: 2018 IEEE 19TH INTERNATIONAL WORKSHOP ON SIGNAL PROCESSING ADVANCES IN WIRELESS COMMUNICATIONS (SPAWC). - : IEEE. - 9781538635124 ; , s. 11-15
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Konferensbidrag (refereegranskat)abstract
- Backscatter communication (BSC) technology can enable ubiquitous deployment of low-cost sustainable wireless devices. In this work we investigate the efficacy of a full-duplex antenna array reader in overcoming the limited communication range bottleneck of monostatic BSCs. As performance is strongly influenced by the channel estimation (CE) quality, we first derive a novel least-squares estimator (LSE) for the forward and backward links between the reader and the tag, assuming that reciprocity holds. After defining the transceiver design at reader using this LSE, we optimize the energy allocation for the CE and information decoding phases, to maximize the average backscattered signal-to-noise ratio (SNR). The unimodality of this SNR in optimization variable along with a tight approximation for the global optimal design are also presented. Lastly, numerical results validate the proposed analysis and present key insights into the optimal LSE and energy allocation.
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| 9. |
- Nomikos, Nikolaos, et al.
(författare)
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Deadline-constrained Bursty Traffic in Random Access Wireless Networks
- 2018
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Ingår i: 2018 IEEE 19th International Workshop on Signal Processing Advances in Wireless Communications (SPAWC). - : IEEE. - 9781538635124
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Konferensbidrag (refereegranskat)abstract
- We consider a network of buffer-aided wireless devices having to transmit deadline-constrained data packets on a slotted-ALOHA random-access channel. While retransmission- based communication enhances reliability, the transmission of packets in the queue is delayed and as a result, they might get dropped before they are transmitted successfully. In this work, we study the performance of deadline-constrained bursty traffic with retransmissions providing a Markov chain-based analysis. The aim is to reveal the trade-off between the packet deadline and the number of retransmissions as a function of the arrival rate, and pave the way towards finding the optimal number of retransmissions, given the packet deadline and packet arrival rate. Furthermore, performance evaluation is conducted for a user with varying transmit probability and different number of retransmissions. The results reveal the effect of these parameters on the drop probability and average throughput showing the values under which, improved performance can be obtained.
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| 10. |
- Tsinos, Christos G., et al.
(författare)
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Symbol-Level Precoding with Low Resolution DACs for Large-Scale Array MU-MIMO Systems
- 2018
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Ingår i: 2018 IEEE 19TH INTERNATIONAL WORKSHOP ON SIGNAL PROCESSING ADVANCES IN WIRELESS COMMUNICATIONS (SPAWC). - : IEEE. - 9781538635124 ; , s. 671-675
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Konferensbidrag (refereegranskat)abstract
- While (Multiple Input-Multiple Output) MIMO systems based on large-scale antenna arrays are seen as the solution to the continuously increasing demands in modern wireless systems, they require high hardware complexity and power consumption. To tackle this, solutions based on low resolution Analog-to-Digital Converters (ADCs) / Digital-to-Analog Converters (DACs) have been developed in the literature where they mainly propose quantized versions of typical channel dependent linear precoding solutions. Alternatively, nonlinear Symbol level Precoding techniques have been recently proposed for downlink Multi User (MU)-MIMO systems with low resolution DACs that achieve significantly improved performance in several cases. The existing SLP approaches support only DACs of 1-bit resolution which result in significant performance degradations, especially when constellations with order greater than 4 are employed. To that end, in this work a novel SLP approach is developed that supports systems with DACs of any resolution and it is applicable for any type of constellation. As it is verified by the presented numerical results, the proposed approach exhibits significantly improved performance when constellations with order greater than 4 are employed and require reduced computational complexity, compared to the existing solutions for the 1-bit DAC case.
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