scholarly journals Revisiting Degrees of Freedom of Full-Duplex Systems with Opportunistic Transmission: An Improved User Scaling Law

2018 ◽  
Author(s):  
Haksoo Kim ◽  
Juyeop Kim ◽  
Sang Won Choi ◽  
Won-Yong Shin
Keyword(s):  
Degrees Of Freedom ◽  
Signal To Noise Ratio ◽  
Scaling Law ◽  
Base Station ◽  
Full Duplex ◽  
Duplex System ◽  
Single Antenna ◽  
Partial Channel ◽  
Minimum Number ◽  
Opportunistic Transmission

It was recently studied how to achieve the optimal degrees of freedom (DoF) in a multi-antenna full-duplex system with partial channel state information (CSI). In this paper, we revisit the DoF of a multiple-antenna full-duplex system using opportunistic transmission under the partial CSI, in which a full-duplex base station having M transmit antennas and M receive antennas supports a set of half-duplex mobile stations (MSs) having a single antenna each. Assuming no self-interference, we present a new hybrid opportunistic scheduling method that achieves the optimal sum DoF under an improved user scaling law. It is shown that the optimal sum DoF of 2M is asymptotically achievable provided that the number of MSs scales faster than SNRM, where SNR denotes the signal-to-noise ratio. This result reveals that in our full-duplex system, better performance on the user scaling law can be obtained without extra CSI, compared to the prior work that showed the required user scaling condition (i.e., the minimum number of MSs for guaranteeing the optimal DoF) of SNR2M−1.

scholarly journals Revisiting Degrees of Freedom of Full-Duplex Systems with Opportunistic Transmission: An Improved User Scaling Law

Entropy ◽  
2018 ◽  
Vol 20 (3) ◽  
pp. 160 ◽  
Author(s):  
Haksoo Kim ◽  
Juyeop Kim ◽  
Sang Choi ◽  
Won-Yong Shin
Keyword(s):  
Degrees Of Freedom ◽  
Scaling Law ◽  
Full Duplex ◽  
Opportunistic Transmission ◽  
Duplex Systems

scholarly journals Degrees-Of-Freedom in Multi-Cloud Based Sectored Cellular Networks

Entropy ◽  
2020 ◽  
Vol 22 (6) ◽  
pp. 668
Author(s):  
Samet Gelincik ◽  
Ghaya Rekaya-Ben Othman
Keyword(s):  
Cellular Networks ◽  
Degrees Of Freedom ◽  
Signal To Noise Ratio ◽  
Base Stations ◽  
Processing Capacity ◽  
Coding Schemes ◽  
Minimum Number ◽  
Cut Set ◽  
Base Band ◽  
Multi Cloud

This paper investigates the achievable per-user degrees-of-freedom (DoF) in multi-cloud based sectored hexagonal cellular networks (M-CRAN) at uplink. The network consists of N base stations (BS) and K ≤ N base band unit pools (BBUP), which function as independent cloud centers. The communication between BSs and BBUPs occurs by means of finite-capacity fronthaul links of capacities C F = μ F · 1 2 log ( 1 + P ) with P denoting transmit power. In the system model, BBUPs have limited processing capacity C BBU = μ BBU · 1 2 log ( 1 + P ) . We propose two different achievability schemes based on dividing the network into non-interfering parallelogram and hexagonal clusters, respectively. The minimum number of users in a cluster is determined by the ratio of BBUPs to BSs, r = K / N . Both of the parallelogram and hexagonal schemes are based on practically implementable beamforming and adapt the way of forming clusters to the sectorization of the cells. Proposed coding schemes improve the sum-rate over naive approaches that ignore cell sectorization, both at finite signal-to-noise ratio (SNR) and in the high-SNR limit. We derive a lower bound on per-user DoF which is a function of μ BBU , μ F , and r. We show that cut-set bound are attained for several cases, the achievability gap between lower and cut-set bounds decreases with the inverse of BBUP-BS ratio 1 r for μ F ≤ 2 M irrespective of μ BBU , and that per-user DoF achieved through hexagonal clustering can not exceed the per-user DoF of parallelogram clustering for any value of μ BBU and r as long as μ F ≤ 2 M . Since the achievability gap decreases with inverse of the BBUP-BS ratio for small and moderate fronthaul capacities, the cut-set bound is almost achieved even for small cluster sizes for this range of fronthaul capacities. For higher fronthaul capacities, the achievability gap is not always tight but decreases with processing capacity. However, the cut-set bound, e.g., at 5 M 6 , can be achieved with a moderate clustering size.

scholarly journals Algorithm to Estimate Direction of Arrival with Interpolated Array Elements for Coprime Array Holes

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Guicai Yu
Keyword(s):  
Degrees Of Freedom ◽  
Signal To Noise Ratio ◽  
Direction Of Arrival ◽  
Array Element ◽  
Regular Pattern ◽  
Minimum Number ◽  
Virtual Array ◽  
Novel Method ◽  
Coprime Arrays ◽  
Coprime Array

A novel method for adding antennas in the coprime arrays is introduced in this study, in order to solve the problem of the reduced degree of freedom of the array in the hole-existing coprime arrays. The minimum number of antennas interpolated in the algorithm maximizes the available degrees of freedom of virtual arrays, and the number of interpolated antennas does not change the original aperture size of the coprime arrays. With the proposed algorithm, the estimate of the direction of arrival is more accurate for a given signal-to-noise ratio. The scheme first finds the regular pattern of hole positions in virtual array elements, and then, according to the regular pattern, the position of the hole of the partial virtual array element is interpolated with the array element antenna at the position of the corresponding coprime arrays. The holes of the virtual array element are filled, giving virtual uniform continuous array elements with maximum degrees of freedom. We use the ESPRIT, and the simulation results show that the proposed algorithm improves the accuracy and resolution of estimates of the direction of arrival.

Improving Physical Layer Security via TAS and Full-Duplex Artificial-Noise-Added Receiver

Frequenz ◽  
2015 ◽  
Vol 69 (7-8) ◽  
Author(s):  
Yajun Zhang ◽  
Tao Liang ◽  
Aiwei Sun
Keyword(s):  
Outage Probability ◽  
Fading Channels ◽  
Antenna Selection ◽  
Signal To Noise Ratio ◽  
Full Duplex ◽  
Artificial Noise ◽  
Secrecy Outage Probability ◽  
Transmit Antenna Selection ◽  
Single Antenna ◽  
Secrecy Outage

AbstractIn this paper, we propose a hybrid scheme called transmit antenna selection and receiver’s artificial noise (TAS–rAN) for security enhancement in multiple-input single-output (MISO) wiretap channels. In this scheme, by using TAS protocol, the transmitter selects a single antenna that maximizes the instantaneous signal-to-noise ratio (SNR) at the full-duplex receiver. While the transmitter uses this antenna to transmit secrecy data, the full-duplex receiver would send artificial noise (AN) to confuse the potential eavesdropper. For the proposed protocol, we consider Rayleigh fading channels with different parameters for the main channel and the eavesdropper’s channel, and derive new closed-form expressions for the exact secrecy outage probability and the asymptotic secrecy outage probability. We demonstrate that the proposed TAS–

Information capacity and bandwidth limitations in the SEM

1989 ◽  
Vol 47 ◽  
pp. 84-85
Author(s):  
D. C. Joy ◽  
R. D. Bunn
Keyword(s):  
Signal To Noise Ratio ◽  
Critical Dimension ◽  
Information Capacity ◽  
Acquisition Time ◽  
Signal To Noise ◽  
Sem Image ◽  
Probe Size ◽  
Minimum Number ◽  
Noise Ratio ◽  
Signal Channel

The information available from an SEM image is limited both by the inherent signal to noise ratio that characterizes the image and as a result of the transformations that it may undergo as it is passed through the amplifying circuits of the instrument. In applications such as Critical Dimension Metrology it is necessary to be able to quantify these limitations in order to be able to assess the likely precision of any measurement made with the microscope.The information capacity of an SEM signal, defined as the minimum number of bits needed to encode the output signal, depends on the signal to noise ratio of the image - which in turn depends on the probe size and source brightness and acquisition time per pixel - and on the efficiency of the specimen in producing the signal that is being observed. A detailed analysis of the secondary electron case shows that the information capacity C (bits/pixel) of the SEM signal channel could be written as :

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