On the Spectral Efficiency and Fairness in Full-Duplex Cellular Networks

To increase the spectral efficiency of wireless networks without requiring full-duplex capability of user devices, a potential solution is the recently proposed three-node full-duplex mode. To realize this potential, networks employing three-node full-duplex transmissions must deal with self-interference and user-to-user interference, which can be managed by frequency channel and power allocation techniques. Whereas previous works investigated either spectral efficient or fair mechanisms, a scheme that balances these two metrics among users is investigated in this paper. This balancing scheme is based on a new solution method of the multi-objective optimization problem to maximize the weighted sum of the per-user spectral efficiency and the minimum spectral efficiency among users. The mixed integer non-linear nature of this problem is dealt by Lagrangian duality. Based on the proposed solution approach, a low-complexity centralized algorithm is developed, which relies on large scale fading measurements that can be advantageously implemented at the base station. Numerical results indicate that the proposed algorithm increases the spectral efficiency and fairness among users without the need of weighting the spectral efficiency. An important conclusion is that managing user-to-user interference by resource assignment and power control is crucial for ensuring spectral efficient and fair operation of full-duplex networks.Comment: 6 pages, 4 figures, accepted in IEEE ICC 2017. arXiv admin note: text overlap with arXiv:1603.0067

Performance Analysis of Network-Assisted Two-Hop D2D Communications

Network-assisted single-hop device-to-device (D2D) communication can increase the spectral and energy efficiency of cellular networks by taking advantage of the proximity, reuse, and hop gains when radio resources are properly managed between the cellular and D2D layers. In this paper we argue that D2D technology can be used to further increase the spectral and energy efficiency if the key D2D radio resource management algorithms are suitably extended to support network assisted multi-hop D2D communications. Specifically, we propose a novel, distributed utility maximizing D2D power control (PC) scheme that is able to balance spectral and energy efficiency while taking into account mode selection and resource allocation constraints that are important in the integrated cellular-D2D environment. Our analysis and numerical results indicate that multi-hop D2D communications combined with the proposed PC scheme can be useful not only for harvesting the potential gains previously identified in the literature, but also for extending the coverage of cellular networks.Comment: 6 pages and 7 figure

Distributed Spectral Efficiency Maximization in Full-Duplex Cellular Networks

Three-node full-duplex is a promising new transmission mode between a full-duplex capable wireless node and two other wireless nodes that use half-duplex transmission and reception respectively. Although three-node full-duplex transmissions can increase the spectral efficiency without requiring full-duplex capability of user devices, inter-node interference - in addition to the inherent self-interference - can severely degrade the performance. Therefore, as methods that provide effective self-interference mitigation evolve, the management of inter-node interference is becoming increasingly important. This paper considers a cellular system in which a full-duplex capable base station serves a set of half-duplex capable users. As the spectral efficiencies achieved by the uplink and downlink transmissions are inherently intertwined, the objective is to device channel assignment and power control algorithms that maximize the weighted sum of the uplink-downlink transmissions. To this end a distributed auction based channel assignment algorithm is proposed, in which the scheduled uplink users and the base station jointly determine the set of downlink users for full-duplex transmission. Realistic system simulations indicate that the spectral efficiency can be up to 89% better than using the traditional half-duplex mode. Furthermore, when the self-interference cancelling level is high, the impact of the user-to-user interference is severe unless properly managed.Comment: 7 pages, 3 figures, accepted in IEEE ICC 2016 - Workshop on Novel Medium Access and Resource Allocation for 5G Network

Clarice Lispector and her art of short story writing : an analysis of "The Egg and the Chicken"

The article presents a critical analysis of Clarice Lispector's short story titled "The Egg and the Chicken" ["O ovo e a galinha"], considered one of Lispector's most complex pieces of writing. The aim of the paper is to draw attention to the complexity of the story and to demonstrate how the text challenges Lispector's short fiction on the level of structure and content. In addition, the article aims to highlight the perspective of interpretation related to Lispector's literary awareness, which has not yet been extensively approached in Poland.Este ensaio apresenta uma análise crítica do conto "O ovo e a galinha", que é considerado um dos contos mais complexos escritos por Clarice Lispector. O objetivo do trabalho é chamar a atenção para a complexidade da história e ilustrar como o texto desafia outros contos em termos de estrutura e conteúdo. Este ensaio pretende também realçar o ângulo de interpretação relacionado com a consciência literária de Lispector, isto é, uma perspectiva que até agora não foi extensivamente abordada na Polônia

Differences in resource assimilation between the unisexual Amazon molly, Poecilia formosa (Poeciliidae) and its sexual host (Poecilia latipinna)

Abstract Unisexual sperm-dependent species depend on a sexual host for reproduction, and must live in sympatry with their sperm donor. If niche overlap between the species is substantial, the intrinsic faster population growth of the unisexual over sexual species can cause competitive exclusion of the host from resources, causing the demise of the unisexual species. However, theoretical models predict that coexistence is possible, even without niche differentiation, if the unisexual species is a poorer competitor than the sexual host and if the effect of the unisexual species on the exploitative abilities of the sexual species is smaller than the effect that the sexually reproducing individuals have among themselves. We tested these predictions in the unisexualbisexual mating complex of Poecilia formosa, and one of its sexual hosts, P. latipinna. Fishes were housed from parturition for 76 days with both conspecific and heterospecific individuals under both limited and ad libitum food regimes. Only one of the predictions of the models was met: the effects of intraspecific competition for P. latipinna were stronger than the effects of interspecific competition. Poecilia latipinna raised with conspecifics with limited food stored fewer fats than both heterospecific P. formosa, and conspecifics raised in any other treatment

Tracing the cosmic growth of supermassive black holes to z~3 with Herschel

We study a sample of Herschel selected galaxies within the Great Observatories Origins Deep Survey-South and the Cosmic Evolution Survey fields in the framework of the Photodetector Array Camera and Spectrometer (PACS) Evolutionary Probe project. Starting from the rich multiwavelength photometric data sets available in both fields, we perform a broad-band spectral energy distribution decomposition to disentangle the possible active galactic nucleus (AGN) contribution from that related to the host galaxy. We find that 37 per cent of the Herschel-selected sample shows signatures of nuclear activity at the 99 per cent confidence level. The probability of revealing AGN activity increases for bright (L 1−1000 > 10 11 L ? ) star-forming galaxies at z > 0.3, becoming about 80 per cent for the brightest (L 1−1000 > 10 12 L ? ) Infrared (IR) galaxies at z≥1. Finally, we reconstruct the AGN bolometric luminosity function and the supermassive black hole growth rate across cosmic time up to z ∼ 3 from a far-IR perspective. This work shows general agreement with most of the panchromatic estimates from the literature, with the global black hole growth peaking at z ∼ 2 and reproducing the observed local black hole mass density with consistent values of the radiative efficiency Erad (∼0.07)