8 research outputs found
On the effect of blockage objects in dense MIMO SWIPT networks
Simultaneous information and power transfer (SWIPT) is characterised by the
ambiguous role of multi-user interference. In short, the beneficial effect of
multi-user interference on RF energy harvesting is obtained at the price of a
reduced link capacity, thus originating nontrivial trade-offs between the
achievable information rate and the harvestable energy. Arguably, in indoor
environments, this trade-off might be affected by the propagation loss due to
blockage objects like walls. Hence, a couple of fundamental questions arise.
How much must the network elements be densified to counteract the blockage
attenuation? Is blockage always detrimental on the achievable rate-energy
trade-off? In this paper, we analyse the performance of an indoor
multiple-input multiple-output (MIMO) SWIPT-enabled network in the attempt to
shed a light of those questions. The effects of the obstacles are examined with
the help of a stochastic approach in which energy transmitters (also referred
to as power heads) are located by using a Poisson Point Process and walls are
generated through a Manhattan Poisson Line Process. The stochastic behaviour of
the signal attenuation and the multi-user interference is studied to obtain the
Joint Complementary Cumulative Distribution Function (J-CCDF) of information
rate and harvested power. Theoretical results are validated through Monte Carlo
simulations. Eventually, the rate-energy trade-off is presented as a function
of the frequency of walls to emphasise the cross-dependences between the
deployment of the network elements and the topology of the venue
Energy efficient MIMO SWIPT by hybrid analog-digital beamforming
In this paper, we investigate the simultaneous wireless information and power transfer (SWIPT) for MIMO systems with limited RF chains at the base station. We focus on the scenario where there is one information decoder with a targeted SINR and several separate energy receivers with energy harvesting thresholds. Based on the observation that the fully-digital beamformer consists of only the information beamformer, we propose an iterative hybrid analog-digital beamforming scheme, where we design the analog beamformer by minimizing the difference between the fully-digital beamformer and the hybrid beamformer, and the optimal solution can be obtained via a geometrical interpretation. Numerical results show that the proposed scheme can achieve a close-to-optimal performance with significant gains in the total power consumption over fully-digital SWIPT
Energy Efficient MIMO SWIPT by Hybrid Analog-Digital Beamforming
In this paper, we investigate the simultaneous wireless
information and power transfer (SWIPT) for MIMO systems
with limited RF chains at the base station. We focus on the
scenario where there is one information decoder with a targeted
SINR and several separate energy receivers with energy harvesting
thresholds. Based on the observation that the fully-digital
beamformer consists of only the information beamformer, we
propose an iterative hybrid analog-digital beamforming scheme,
where we design the analog beamformer by minimizing the
difference between the fully-digital beamformer and the hybrid
beamformer, and the optimal solution can be obtained via
a geometrical interpretation. Numerical results show that the
proposed scheme can achieve a close-to-optimal performance with
significant gains in the total power consumption over fully-digital
SWIPT
SWIPT-based Real-Time Mobile Computing Systems: A Stochastic Geometry Perspective
Driven by the Internet of Things vision, recent years have seen the rise of
new horizons for the wireless ecosystem in which a very large number of mobile
low power devices interact to run sophisticated applications. The main
hindrance to the massive deployment of low power nodes is most probably the
prohibitive maintenance cost of battery replacement and the ecotoxicity of the
battery production/end-of-life. An emerging research direction to avoid battery
replacement is the combination of radio frequency energy harvesting and mobile
computing (MC). In this paper, we propose the use of simultaneous information
and power transfer (SWIPT) to control the distributed computation process while
delivering power to perform the computation tasks requested. A real-time MC
system is considered, meaning that the trade-off between the information rate
and the energy harvested must be carefully chosen to guarantee that the CPU may
perform tasks of given complexity before receiving a new control signal. In
order to provide a system-level perspective on the performance of SWIPT-MC
networks, we propose a mathematical framework based on stochastic geometry to
characterise the rate-energy trade-off of the system. The resulting achievable
performance region is then put in relation with the CPU energy consumption to
investigate the operating conditions of real-time computing systems. Finally,
numerical results illustrate the joint effect of the network densification and
the propagation environment on the optimisation of the CPU usage
Outage analysis of the power splitting based underlay cooperative cognitive radio networks
In the present paper, we investigate the performance of the simultaneous wireless information and power transfer (SWIPT) based cooperative cognitive radio networks (CCRNs). In particular, the outage probability is derived in the closed-form expressions under the opportunistic partial relay selection. Different from the conventional CRNs in which the transmit power of the secondary transmitters count merely on the aggregate interference measured on the primary networks, the transmit power of the SWIPT-enabled transmitters is also constrained by the harvested energy. As a result, the mathematical framework involves more correlated random variables and, thus, is of higher complexity. Monte Carlo simulations are given to corroborate the accuracy of the mathematical analysis and to shed light on the behavior of the OP with respect to several important parameters, e.g., the transmit power and the number of relays. Our findings illustrate that increasing the transmit power and/or the number of relays is beneficial for the outage probability.Web of Science2122art. no. 765
Energy Efficient SWIPT: From Fully-Digital to Hybrid Analog-Digital Beamforming
CCBY Simultaneous wireless information and power transfer (SWIPT) enables the transmission of information symbols and energy simultaneously. In this paper, we study the MIMO SWIPT systems with limited RF chains at the base station. We focus on the scenario where there is one information decoder with a target SINR and several separate energy harvesting receivers with harvested energy thresholds. To motivate our energy-efficient hybrid analog-digital beamforming strategy, the fully-digital power minimization problem is firstly analyzed, where we mathematically show that the optimal beamformer consists of only the information beamformer, and derive closed-form beamformers for a number of special cases. Based on this result, we further consider hybrid beamforming and propose an iterative scheme where the analog and digital beamformers are alternately updated. For the proposed scheme, in each iteration we design the analog beamformer by minimizing the difference between the fully-digital beamformer and the hybrid beamformer. Based on our above analysis for fully-digital case, the optimal solution for analog beamformer can be obtained via a geometrical interpretation. We further design the robust beamformers for the proposed schemes, when only imperfect channel state information (CSI) is available. The numerical results show that the proposed iterative designs achieve a close-to-optimal performance with significant gains in the total power consumption over fully-digital SWIPT
MIMO Cellular Networks with Simultaneous Wireless Information and Power Transfer
International audienceIn this paper, we introduce a mathematical approach for system-level analysis and optimization of densely deployed multiple-antenna cellular networks, where low-energy devices are capable of decoding information data and harvesting power simultaneously. The base stations are assumed to be deployed according to a Poisson point process and tools from stochastic geometry are exploited to quantify the trade-off in terms of information rate and harvested power. It is shown that multiple-antenna transmission is capable of increasing information rate and harvested power at the same time
Multiple-Antenna Systems: From Generic to Hardware-Informed Precoding Designs
5G-and-beyond communication systems are expected to be in a heterogeneous form of multiple-antenna cellular base stations (BSs) overlaid with small cells. The fully-digital BS structures can incur significant power consumption and hardware complexity. Moreover, the wireless BSs for small cells usually have strict size constraints, which incur additional hardware effects such as mutual coupling (MC). Consequently, the transmission techniques designed for future wireless communication systems should respect the hardware structures at the BSs. For this reason, in this thesis we extend generic downlink precoding to more advanced hardware-informed transmission techniques for a variety of BS structures. This thesis firstly extends the vector perturbation (VP) precoding to multiple-modulation scenarios, where existing VP-based techniques are sub-optimal. Subsequently, this thesis focuses on the downlink transmission designs for hardware effects in the form of MC, limited number of radio frequency (RF) chains, and low-precision digital-to-analog converters (DACs). For these scenarios, existing precoding techniques are either sub-optimal or not directly applicable due to the specific hardware constraints. In this context, this thesis first proposes analog-digital (AD) precoding methods for MC exploitation in compact single-user multiple-antenna systems with the concept of constructive interference, and further extends the idea of MC exploitation to multi-user scenarios with a joint optimisation on the precoding matrix and the mutual coupling effect. We further consider precoding for wireless BSs with a limited number of RF chains, in the form of compact parasitic antenna array as well as hybrid analog-digital structures designed for large-scale multiple-antenna systems. In addition, with a reformulation of the constructive interference, this thesis also considers the low-complexity precoding design for the use of low-resolution DACs for a massive-antenna array at the BSs. Analytical and numerical results reveal an improved performance of the proposed techniques compared to the state-of-the-art approaches, which validates the effectiveness of the introduced methods