| 1. |
- Aabel, Lise, 1992, et al.
(författare)
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Distributed Massive MIMO via all-Digital Radio Over Fiber
- 2020
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Ingår i: Conference Record - Asilomar Conference on Signals, Systems and Computers. - 1058-6393. ; 2020-November, s. 319-323
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Konferensbidrag (refereegranskat)abstract
- A crucial challenge in the implementation of distributed massive multiple-input multiple-output (MIMO) architectures is to provide phase coherence while, at the same time, limit the complexity of the remote-radio heads (RRHs), which is important for cost-efficient scalability. To address this challenge, we present in this paper a phase-coherent distributed MIMO architecture, based on off-the-shelf, low-cost components. In the proposed architecture, up- and down-conversion are carried out at the central unit (CU). The RRHs are connected to the CU by means of optical fibers carrying oversampled radio-frequency (RF) 1-bit signals. In the downlink, the 1-bit signal is generated via sigma-delta modulation. At the RRH, the RF signal is recovered from the 1-bit signal through a bandpass filter and a power amplifier, and then fed to an antenna. In the uplink, the 1-bit signal is generated by a comparator whose inputs are the low-noise-amplified received RF signal and a suitably designed dither signal. The performance of the proposed architecture is evaluated with satisfactory results both via simulation and measurements from a testbed.
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| 2. |
- Arslan, Mehmet Ali, et al.
(författare)
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Partitioning and Mapping Dynamic Dataflow Programs
- 2012
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Ingår i: [Host publication title missing]. - 1058-6393. ; , s. 1452-1456
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Konferensbidrag (refereegranskat)abstract
- Partitioning and mapping are important design decisions in exploiting the parallelism of programs that are to be run on systems with multiple processing elements. In this paper we introduce a fast, incremental approach for mapping dynamic dataflow programs to multiprocessor systems. We use causation traces and architecture descriptions as input for the mapping process that devises several heuristics for reaching a short makespan for the given trace. We evaluate our approach by comparing our results to two different lower bounds and another algorithm used often in solving mapping problems: simulated annealing.
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| 3. |
- Atzeni, Italo, et al.
(författare)
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Low-Resolution Massive MIMO Under Hardware Power Consumption Constraints
- 2021
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Ingår i: Conference Record - Asilomar Conference on Signals, Systems and Computers. - 1058-6393. - 9781665458283
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Konferensbidrag (refereegranskat)abstract
- We consider a fully digital massive multipleinput multiple-output architecture with low-resolution analogto-digital/digital-to-analog converters (ADCs/DACs) at the base station (BS) and analyze the performance trade-off between the number of BS antennas, the resolution of the ADCs/DACs, and the bandwidth. Assuming a hardware power consumption constraint, we determine the relationship between these design parameters by using a realistic model for the power consumption of the ADCs/DACs and the radio frequency chains. Considering uplink pilot-aided channel estimation, we build on the Bussgang decomposition to derive tractable expressions for uplink and downlink ergodic achievable sum rates. Numerical results show that the ergodic performance is boosted when many BS antennas with very low resolution (i.e., 2 to 3 bits) are adopted in both the uplink and the downlink.
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| 4. |
- Bencheikh Lehocine, Chouaib, 1993, et al.
(författare)
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Sensitivity analysis of beamforming techniques for periodic broadcast V2V communication
- 2021
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Ingår i: Conference Record - Asilomar Conference on Signals, Systems and Computers. - 1058-6393. ; Volume 2021-October, s. 61-66
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Konferensbidrag (refereegranskat)abstract
- In this work, we extend the results of two previously proposed transmit beamforming techniques for periodic, broadcast, vehicle-to-vehicle communication with a common fixed broadcast period, to the scenario where vehicular users (VUs) use different, and potentially varying broadcast periods. The two techniques, analog beamforming network (ABN) of phase shifters and antenna switching network (ASN), were previously developed in accordance with a multiple antenna receiver that employs an analog combining network (ACN) of phase shifters. To accommodate the use of multiple broadcast periods, we propose the design of phase shifter parameters of ABN-ACN and ASN-ACN systems using a design period Td. Then, we analytically derive sets of broadcast periods that sustain optimality, in the sense that the sum signal-to-noise ratio (SNR) of Kconsecutive packets for any receiving VU is maximized. Next, we provide guidelines on how to set Td to ensure a sufficient granularity of the sets of optimal broadcast periods. Finally, we investigate using numerical computations the effect of certain design choices on the sensitivity of ABN/ASN-ACN systems to small variations of the broadcast period.
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| 5. |
- Callebaut, Gilles, et al.
(författare)
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Massive MIMO goes Sub-GHz : Implementation and Experimental Exploration for LPWANs
- 2020
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Ingår i: Conference Record of the 54th Asilomar Conference on Signals, Systems and Computers, ACSSC 2020. - 1058-6393. - 9780738131269 ; 2020-November, s. 1101-1105
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Konferensbidrag (refereegranskat)abstract
- Low-Power Wide-Area Networks operating in the unlicensed bands are being deployed to connect a rapidly growing number of Internet-of-Things devices. While the unlicensed sub-GHz band offers favorable propagation for long-range connections, measurements show that the energy consumption of the nodes is still mostly dominated by the wireless transmission affecting their autonomy. We investigate the potential benefits of deploying massive MIMO technology to increase system reliability and at the same time support low-energy devices with good coverage at sub-GHz frequencies. The impact of different antenna configurations and propagation conditions is analyzed. Both actual average experienced array gain and channel hardening are examined. The assessment demonstrates the effect of channel hardening as well as the potential benefits of the experienced array gain. These measurements serve as a first assessment of the channel conditions of massive MIMO at sub-GHz frequencies and are, to the best of our knowledge, the first of its kind.
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| 6. |
- Castaneda, Oscar, et al.
(författare)
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Finite-Alphabet Wiener Filter Precoding for mmWave Massive MU-MIMO Systems
- 2019
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Ingår i: Conference Record - Asilomar Conference on Signals, Systems and Computers. - 1058-6393. ; , s. 178-183
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Konferensbidrag (refereegranskat)abstract
- Power consumption of multi-user (MU) precoding is a major concern in all-digital massive MU multiple-input multiple-output (MIMO) base-stations with hundreds of antenna elements operating at millimeter-wave (mmWave) frequencies. We propose to replace part of the linear Wiener filter (WF) precoding matrix by a finite-alphabet WF precoding (FAWP) matrix, which enables the use of low-precision hardware that consumes low power and area. To minimize the performance loss of our approach, we present methods that efficiently compute FAWP matrices that best mimic the WF precoder. Our results show that FAWP matrices approach infinite-precision error-rate and error-vector magnitude performance with only 3-bit precoding weights, even when operating in realistic mmWave channels. Hence, FAWP is a promising approach to substantially reduce power consumption and silicon area in all-digital mmWave massive MU-MIMO systems.
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| 7. |
- Castañeda, Oscar, et al.
(författare)
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Hardware-Friendly Two-Stage Spatial Equalization for All-Digital mmWave Massive MU-MIMO
- 2020
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Ingår i: Conference Record - Asilomar Conference on Signals, Systems and Computers. - 1058-6393. ; 2020-November, s. 388-392
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Konferensbidrag (refereegranskat)abstract
- Next generation wireless communication systems are expected to combine millimeter-wave communication with massive multi-user multiple-input multiple-output technology. All-digital base-station implementations for such systems need to process high-dimensional data at extremely high rates, which results in excessively high power consumption. In this paper, we propose two-stage spatial equalizers that first reduce the problem dimension by means of a hardware-friendly, low-resolution linear transform followed by spatial equalization on a lower-dimensional signal. We consider adaptive and non-adaptive dimensionality reduction strategies and demonstrate that the proposed two-stage spatial equalizers are able to approach the performance of conventional linear spatial equalizers that directly operate on high-dimensional data, while offering the potential to reduce the power consumption of spatial equalization.
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| 8. |
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| 9. |
- Cedersjö, Gustav, et al.
(författare)
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Toward Efficient Execution of Dataflow Actors
- 2012
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Ingår i: [Host publication title missing]. - 1058-6393. ; , s. 1465-1469
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Konferensbidrag (refereegranskat)abstract
- Dataflow descriptions are a natural match to application areas such as signal processing, cryptography, networking, image processing, and media coding. This paper addresses the problem of efficiently executing the basic elements of a dataflow program, its actors, written in a language such as MPEG's RVC-CAL. Using actor machines as an execution model for dataflow actors, we devise a metric for measuring the quality of a translation in terms of program size and execution efficiency, and then build, evaluate and compare a number of translators with each other and prior art, using MPEG reference code as a benchmark.
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| 10. |
- Cheng, Sijia, et al.
(författare)
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MmWave Massive MIMO Processing in Demanding Environments - An Aircraft Cabin Deployment Study
- 2023
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Ingår i: Conference Record of the 57th Asilomar Conference on Signals, Systems and Computers, ACSSC 2023. - 1058-6393. - 9798350325744 ; , s. 1631-1635
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Konferensbidrag (refereegranskat)abstract
- Massive multiple-input multiple-output (MIMO) technology will continue playing an important role in beyond 5G wireless systems. Fully digital beamforming at the millimeter wave (mmWave) spectrum enables applications that require high data rates and low latency. This paper investigates the development and deployment of mmWave massive MIMO systems in an in-flight cabin environment, from both system performance and hardware implementation aspects. Ray-tracing methods with realistic geometry coefficients captured from commercial airplane models are used to represent this in-door dense environment. A hardware-in-the-loop simulator running on the AMD/Xilinx PYNQ FPGA is leveraged to conduct fast design space exploration. The outcomes of our investigation provide insights and guidelines in strategies for implementing and deploying mmWave massive MIMO systems in-flight cabins, for instance, how to place and distribute access points to enhance coverage and serve quality and the appropriate quantization strategy balancing hardware cost and signal processing quality.
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