scholarly journals A modified GADIA-based upper-bound to the capacity of Gaussian general N-relay networks

2021 ◽  
Author(s):  
Zekeriya Uykan ◽  
Riku Jäntti
Keyword(s):  
Upper Bound ◽  
Simple Algorithm ◽  
Relay Network ◽  
Maximization Problem ◽  
Interference Avoidance ◽  
Gain Matrix ◽  
Power Domain ◽  
Information Maximization ◽  
Capacity Bound ◽  
Min Cut

AbstractIn this paper, we present a general Gaussian N-relay network by allowing relays to communicate to each other and allowing a direct channel between source and destination as compared to the standard diamond network in Nazaroğlu et al. (IEEE Trans Inf Theory 60:6329–6341, 2014) at the cost of extra channel uses. Our main focus is to examine the min-cut bound capacities of the relay network. Very recently, the results in Uykan (IEEE Trans Neural Netw Learn Syst 31:3294–3304, 2020) imply that the GADIA in Babadi and Tarokh (IEEE Trans Inf Theory 56:6228–6252, 2010), a pioneering algorithm in the interference avoidance literature, actually performs max-cut of a given power-domain (nonnegative) link gain matrix in the 2-channel case. Using the results of the diamond network in Nazaroğlu et al. (2014) and the results in Uykan (2020), in this paper, we (i) turn the mutual information maximization problem in the Gaussian N-relay network into an upper bound minimization problem, (ii) propose a modified GADIA-based algorithm to find the min-cut capacity bound and (iii) present an upper and a lower bound to its min-cut capacity bound using the modified GADIA as applied to the defined “squared channel gain matrix/graph”. Some advantages of the proposed modified GADIA-based simple algorithm are as follows: (1) The Gaussian N-relay network can determine the relay clusters in a distributed fashion and (2) the presented upper bound gives an insight into whether allowing the relays to communicate to each other pays off the extra channel uses or not as far as the min-cut capacity bound is concerned. The simulation results confirm the findings. Furthermore, the min-cut upper bound found by the proposed modified-GADIA is verified by the cut-set bounds found by the spectral clustering based solutions as well.

scholarly journals Performance Optimization of Hybrid Satellite-Terrestrial Relay Network Based on CR-NOMA

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5177
Author(s):  
Long Zhao ◽  
Tao Liang ◽  
Kang An
Keyword(s):  
Performance Optimization ◽  
Transmission Rate ◽  
Relay Network ◽  
High Signal ◽  
Decode And Forward ◽  
Obvious Effect ◽  
Selection Scheme ◽  
Outage Performance ◽  
Multiple User ◽  
Power Domain

The non-orthogonal multiple access (NOMA) scheme realizes the transmission of multiple user signals at the same time and frequency resource block through power domain multiplexing, which improves the system transmission rate and user fairness. In this paper, we propose a joint relay-and-antenna selection scheme based on the cognitive radio scenario. This scheme can achieve the maximum communication rate of the secondary user when the primary user maintains the optimal outage performance. In the considered system both terrestrial relays and users are deployed with multi-antenna configurations and the terrestrial relays adopt the decode-and-forward (DF) strategy to achieve communication between satellites and users. Then, we derive the exact outage probability expression of each user in the system and the asymptotic probability expression under high signal-to-noise ratio (SNR). Numeric results demonstrate that increasing the number of relays and antennas on the terrestrial nodes can both improve system outage performance. Moreover, the number of relays imposes a more obvious effect on the achievable system performance.

Heavy traffic analysis of a queueing system with bounded capacity for two types of customers

1999 ◽  
Vol 36 (4) ◽  
pp. 1155-1166 ◽  
Author(s):  
David Perry ◽  
Wolfgang Stadje
Keyword(s):  
Brownian Motion ◽  
Poisson Process ◽  
Upper Bound ◽  
Queueing System ◽  
Service System ◽  
Heavy Traffic ◽  
Arrival Times ◽  
Brownian Motion With Drift ◽  
Heavy Traffic Analysis ◽  
Capacity Bound

We study a service system with a fixed upper bound for its workload and two independent inflows of customers: frequent ‘small’ ones and occasional ‘large’ ones. The workload process generated by the small customers is modelled by a Brownian motion with drift, while the arrival times of the large customers form a Poisson process and their service times are exponentially distributed. The workload process is reflected at zero and at its upper capacity bound. We derive the stationary distribution of the workload and several related quantities and compute various important characteristics of the system.

A Complex Cell-Like Receptive Field Obtained by Information Maximization

2001 ◽  
Vol 13 (3) ◽  
pp. 547-562 ◽  
Author(s):  
Kenji Okajima ◽  
Hitoshi Imaoka
Keyword(s):  
Signal To Noise Ratio ◽  
Energy Model ◽  
Linear Operators ◽  
Maximization Problem ◽  
Complex Cell ◽  
Signal To Noise ◽  
Information Theoretic ◽  
Complex Cells ◽  
Information Maximization ◽  
Ratio Limit

The energy model (Pollen & Ronner, 1983; Adelson & Bergen, 1985) for a complex cell in the visual cortex is investigated theoretically. The energy model describes the output of a complex cell as the squared sum of outputs of two linear operators. An information-maximization problem to determine the two linear operators is investigated assuming the low signal-to-noise ratio limit and a localization term in the objective function. As a result, two linear operators characterized by a quadrature pair of Gabor functions are obtained as solutions. The result agrees with the energy model, which well describes the shift-invariant and orientation-selective responses of actual complex cells, and thus suggests that complex cells are optimally designed from an information-theoretic viewpoint.

Heavy traffic analysis of a queueing system with bounded capacity for two types of customers

1999 ◽  
Vol 36 (04) ◽  
pp. 1155-1166 ◽  
Author(s):  
David Perry ◽  
Wolfgang Stadje
Keyword(s):  
Brownian Motion ◽  
Poisson Process ◽  
Upper Bound ◽  
Queueing System ◽  
Service System ◽  
Heavy Traffic ◽  
Arrival Times ◽  
Brownian Motion With Drift ◽  
Heavy Traffic Analysis ◽  
Capacity Bound

We study a service system with a fixed upper bound for its workload and two independent inflows of customers: frequent ‘small’ ones and occasional ‘large’ ones. The workload process generated by the small customers is modelled by a Brownian motion with drift, while the arrival times of the large customers form a Poisson process and their service times are exponentially distributed. The workload process is reflected at zero and at its upper capacity bound. We derive the stationary distribution of the workload and several related quantities and compute various important characteristics of the system.

scholarly journals Symmetric Distributed Termination

1985 ◽  
Vol 14 (189) ◽  
Author(s):  
Ole Eriksen ◽  
Sven Skyum
Keyword(s):  
Upper Bound ◽  
Simple Algorithm ◽  
Distributed Computation ◽  
Directed Networks ◽  
Strongly Connected ◽  
Termination Problem ◽  
Special Master

In this paper we present a simple algorithm for deciding when to terminate a distributed computation. Former solutions to the termination problem are restricted to rings and undirected connected networks, and they rely on the existence of a special master processor present in the network. The class of configurations for which our algorithm is applicable is the most general possible, namely the class of configurations, where the underlying (directed) networks are strongly connected. If the network is not strongly connected then there exists a group of processors which cannot send messages to the rest and it becomes impossible to detect when to terminate. Furthermore, the algorithm does not require a special master processor acting differently from the others. The only information needed is an upper bound on the diameter of the network (the number of processors, for example). The protocol for all processors is in other words identical.

Placing and scheduling many depth sensors for wide coverage and efficient mapping in versatile legged robots

2019 ◽  
Vol 39 (4) ◽  
pp. 431-460 ◽  
Author(s):  
Martim Brandão ◽  
Rui Figueiredo ◽  
Kazuki Takagi ◽  
Alexandre Bernardino ◽  
Kenji Hashimoto ◽  
...  
Keyword(s):  
Information Gain ◽  
State Of The Art ◽  
Scheduling Algorithm ◽  
Legged Robots ◽  
Maximization Problem ◽  
Depth Sensors ◽  
Trade Offs ◽  
Information Maximization ◽  
Final System ◽  
Visual Coverage

This article tackles the problem of designing 3D perception systems for robots with high visual requirements, such as versatile legged robots capable of different locomotion styles. In order to guarantee high visual coverage in varied conditions (e.g., biped walking, quadruped walking, ladder climbing), such robots need to be equipped with a large number of sensors, while at the same time managing the computational requirements that arise from such a system. We tackle this problem at both levels: sensor placement (how many sensors to install on the robot and where) and run-time acquisition scheduling under computational constraints (not all sensors can be acquired and processed at the same time). Our first contribution is a methodology for designing perception systems with a large number of depth sensors scattered throughout the links of a robot, using multi-objective optimization for optimal trade-offs between visual coverage and the number of sensors. We estimate the Pareto front of these objectives through evolutionary optimization, and implement a solution on a real legged robot. Our formulation includes constraints on task-specific coverage and design symmetry, which lead to reliable coverage and fast convergence of the optimization problem. Our second contribution is an algorithm for lowering the computational burden of mapping with such a high number of sensors, formulated as an information-maximization problem with several sampling techniques for speed. Our final system uses 20 depth sensors scattered throughout the robot, which can either be acquired simultaneously or optimally scheduled for low CPU usage while maximizing mapping quality. We show that, when compared with state-of-the-art robotic platforms, our system has higher coverage across a higher number of tasks, thus being suitable for challenging environments and versatile robots. We also demonstrate that our scheduling algorithm allows higher mapping performance to be obtained than with naïve and state-of-the-art methods by leveraging on measures of information gain and self-occlusion at low computational costs.

scholarly journals Distributed Beamforming Design for Nonregenerative Two-Way Relay Networks with Simultaneous Wireless Information and Power Transfer

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Keyun Liao ◽  
Sai Zhao ◽  
Yusi Long ◽  
Gaofei Huang ◽  
Dong Tang
Keyword(s):  
Energy Harvesting ◽  
Upper Bound ◽  
Mean Squared Error ◽  
Signal To Noise Ratio ◽  
Closed Form Solution ◽  
Form Solution ◽  
Relay Network ◽  
Power Transfer ◽  
Distributed Beamforming ◽  
Relay Nodes

This paper considers the distributed beamforming design for a simultaneous wireless information and power transfer (SWIPT) in two-way relay network, which consists of two sources, K relay nodes and one energy harvesting (EH) node. For such a network, assuming perfect channel state information (CSI) is available, and we study two different beamforming design schemes. As the first scheme, we design the beamformer through minimization of the average mean squared error (MSE) subject to the total transmit power constraint at the relays and the energy harvesting constraint at the EH receiver. Due to the intractable expression of the objective function, an upper bound of MSE is derived via the approximation of the signal-to-noise ratio (SNR). Based on the minimization of this upper bound, this problem can be turned into a convex feasibility semidefinite programming (SDP) and, therefore, can be efficiently solved using interior point method. To reduce the computational complexity, a suboptimal beamforming scheme is proposed in the second scheme, for which the optimization problem could be recast to the form of the Rayleigh–Ritz ratio and a closed-form solution is obtained. Numerical results are provided and analyzed to demonstrate the efficiency of our proposed beamforming schemes.

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