33,099 research outputs found
Massive MIMO 1-Bit DAC Transmission: A Low-Complexity Symbol Scaling Approach
We study multi-user massive multiple-input single-output (MISO) systems and
focus on downlink transmission, where the base station (BS) employs a large
antenna array with low-cost 1-bit digital-to-analog converters (DACs). The
direct combination of existing beamforming schemes with 1-bit DACs is shown to
lead to an error floor at medium-to-high SNR regime, due to the coarse
quantization of the DACs with limited precision. In this paper, based on the
constructive interference we consider both a quantized linear beamforming
scheme where we analytically obtain the optimal beamforming matrix, and a
non-linear mapping scheme where we directly design the transmit signal vector.
Due to the 1-bit quantization, the formulated optimization for the non-linear
mapping scheme is shown to be non-convex. To solve this problem, the non-convex
constraints of the 1-bit DACs are firstly relaxed, followed by an element-wise
normalization to satisfy the 1-bit DAC transmission. We further propose a
low-complexity symbol scaling scheme that consists of three stages, in which
the quantized transmit signal on each antenna element is selected sequentially.
Numerical results show that the proposed symbol scaling scheme achieves a
comparable performance to the optimization-based non-linear mapping approach,
while its corresponding complexity is negligible compared to that of the
non-linear scheme.Comment: 15 page
Towards a Systematic Framework for the Modelling of the Allocation of Carbon Dioxide Emission Quotas in China
The needs for effectively controlling carbon dioxide emissions and properly allocating carbon dioxide emission permits or allowances in China have never been so great. In this paper, a systematic multi-agent-based framework for the modelling and analysis of the allocation of carbon dioxide emission quotas in China is proposed. A carbon trading market model as the core of the activities of allocation management is constructed and discussed. In addition, examples of the modelling and simulation work are presented
Wigner functions of thermo number state, photon subtracted and added thermo vacuum state at finite temperature
Based on Takahashi-Umezawa thermo field dynamics and the order-invariance of
Weyl ordered operators under similar transformations, we present a new approach
to deriving the exact Wigner functions of thermo number state, photon
subtracted and added thermo vacuum state. We find that these Wigner functions
are related to the Gaussian-Laguerre type functions of temperature, whose
statistical properties are then analysed.Comment: 10 pages and 2 figure
Multi-Agent-Based Modelling, Simulation and Heterogeneity Analysis of the Management Strategies for Enterprise Carbon Assets
Low carbon competitive patterns based upon low-carbon assets have developed in industries across the world. In the paper, three typical enterprises are used as examples to identify carbon assets from the perspective of enterprise business contexts, and to extract the interactive framework. This paper makes quantitative description of the value contribution principle of each carbon asset module and sets up the simulation strategies for relevant carbon assets. On the basis of these, an Agent-Based Modelling & Simulation (ABMS) system is created and built to simulate and analyse the difference in the evolution of carbon assets. The results demonstrate the emergent properties of enterprise carbon assets. The simulation study also shows remarkable heterogeneity of evolution paths with low-carbon technologies and low-carbon brands, which are the key factors leading to the evolution of other carbon assets and the adjustment of strategies. Finally, recommendations are made to improve the management of enterprises carbon assets
Quantum mechanical photon-count formula derived by entangled state representation
By introducing the thermo entangled state representation, we derived four new
photocount distribution formulas for a given density operator of light field.
It is shown that these new formulas, which is convenient to calculate the
photocount, can be expressed as such integrations over Laguree-Gaussian
function with characteristic function, Wigner function, Q-function, and
P-function, respectively.Comment: 5 pages, no figur
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