This paper presents a smart antenna system using a combination of nonconventional least square (NCLS) optimization and direct data domain least square (D3LS) for direction-of-arrival (DOA) estimation and beamforming, ...
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A smart antenna was proposed to improve wireless communication systems. The smart antenna may comprises direction-of-arrival (DOA) estimation and/or adaptive antenna. The DOA estimation technique is used to estimate d...
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The aim of this study is to compare forces generated by three different orthodontic closed coil springs supplied by three companies, optical fiber Bragg gratins are used to evaluate the force of closing of springs. &#...
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Like many institutions across the country, we have embarked on the development of experiences and programs related to the objective of achieving global competence in our engineering students. These internationally-ori...
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Thin film gallium nitride (GaN) scintillators have been produced by MOCVD and made neutron-sensitive by applying an enriched lithium-6 fluoride ( 6LiF) conversion layer. The 6Li(n,α) reaction produces both alpha and ...
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This paper deals with the statistical modeling of uplink inter-cell interference (ICI) considering greedy scheduling with power adaptation based on channel conditions. The derived model is implicitly generalized for a...
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ISBN:
(纸本)9781467318808
This paper deals with the statistical modeling of uplink inter-cell interference (ICI) considering greedy scheduling with power adaptation based on channel conditions. The derived model is implicitly generalized for any kind of shadowing and fading environments. More precisely, we develop a generic model for the distribution of ICI based on the locations of the allocated users and their transmit powers. The derived model is utilized to evaluate important network performance metrics such as ergodic capacity, average fairness and average power preservation numerically. Monte-Carlo simulation details are included to support the analysis and show the accuracy of the derived expressions. In parallel to the literature, we show that greedy scheduling with power adaptation reduces the ICI, average power consumption of users, and enhances the average fairness among users, compared to the case without power adaptation.
This paper considers the problem of channel reservation schemes for reservation-based MAC protocols with different priorities in wireless communication networks. A framework for designing such channel reservation prot...
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ISBN:
(纸本)9781467311564
This paper considers the problem of channel reservation schemes for reservation-based MAC protocols with different priorities in wireless communication networks. A framework for designing such channel reservation protocols based on p-persistent is introduced. This framework allows us to explore several different prioritization mechanisms which are devised to serve different prioritization policies or requirements. This leads to the development of five channel reservation schemes, namely, FPT+MP, FPT+MLT, FPT+SCS, FPT+PCP and FPT+HFF. The average number of successful reservations for users of different priorities is evaluated as a primary performance measure. Unlike other previous works where different priorities exhibit strict differentiation, our success ratio (γ) is defined to illustrate how much different priorities are differentiated. In doing so, we seek for a channel reservation scheme that can satisfy the required γ, while maximizing the channel utilization. Numerical results show that the combined scheme of FPT+MP and FPT+SCS schemes is the most effective scheme, possessing all desirable key features.
A MAC protocol that depends on overheard information for its collision avoidance, such as Carrier Sense Multiple Access (CSMA) [1], may not work well in underwater, due to the long propagation delay characteristic of ...
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A MAC protocol that depends on overheard information for its collision avoidance, such as Carrier Sense Multiple Access (CSMA) [1], may not work well in underwater, due to the long propagation delay characteristic of an underwater acoustic (UWA) channel. In such channel, the overheard information may already become obsolete by the time it reaches the node and, thus, should not be taken into account in the collision avoidance mechanism. Intuitively, the degree of usefulness of overheard information plays an important role in determining the network performance for channel listening-based MAC protocols. In this paper, we analytically study the usefulness of overheard information for collision avoidance in two different channel listening-based MAC protocols: (1) CSMA [1] and (2) Aloha-CA [2]. From our study, it is shown that the overheard information is beneficial for collision avoidance only if certain conditions can be satisfied. More specifically, in order for a node that overhears an ongoing transmission to be able to utilize the extracted information for collision avoidance, the node must be within a bounded region that is determined by the relative positions of the sender and the receiver, the packet's transmission time, as well as the length of the packet's header. Based on this analysis, we also present the “usefulness index (U)” which is defined as the degree of usefulness of information overheard.
We derive a semi-analytical expression for the uplink inter-cell interference (ICI) assuming proportional fair scheduling (with a maximum normalized signal-to-noise ratio (SNR) criterion) deployed in the cellular netw...
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We derive a semi-analytical expression for the uplink inter-cell interference (ICI) assuming proportional fair scheduling (with a maximum normalized signal-to-noise ratio (SNR) criterion) deployed in the cellular network. The derived expression can be customized for different models of channel statistics that can capture path loss, shadowing, and fading. Firstly, we derive an expression for the distribution of the locations of the allocated user in a given cell. Then, we derive the distribution and moment generating function of the uplink ICI from one interfering cell. Finally, we determine the moment generating function of the cumulative uplink ICI from all interfering cells. The derived expression is utilized to evaluate important network performance metrics such as outage probability and fairness among users. The accuracy of the derived expressions is verified by comparing the obtained results to Monte Carlo simulations.
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