Hybrid cognitive radio (CR) networks can jointly utilize both licensed and unlicensed radio resources to gain better performance over pure licensed/unlicensed networks. This paper studies the ...system-level capacity of a hybrid cellular network that consists of licensed base stations (BSs) and unlicensed CR relays. Two limiting cases are considered, in which the CR relays are assumed to have infinite cache and no cache, respectively. We systematically derive the system capacity under different simplifying assumptions on interference and path loss. Our results reveal how the system capacity is related to various system parameters such as BS/relay density, bandwidth, power, and CR reliability. Such an insight can be useful for the planning of future heterogeneous cellular networks.
Companies today are aggressively finding ways to improve top-line growth by introducing innovative products faster to the market. To achieve both innovation and accelerated rollout, many are turning ...to techniques such as Stage Gate approaches to improve engineering and marketing collaborations to clarify short term resource allocations (day to day plan with employee assignment). While Stage Gate approaches have been shown to result in better project coordination and faster time to market by doing projects right, research also indicates the need to ensure alignment to company strategy by doing the right projects within the allocated annual budget through medium term (rough cut capacity plan with employee requirements) and long term resource allocations (business / strategic plan with funding requirements). Today, such medium to long term resource allocation methodologies tend to be broadly consolidated under Research and Development (R&D) product portfolio management. We argue that there is value in a philosophical change in viewing R&D product portfolio management from the context of (1.) long and medium term resource allocation phases separately, (2.) focusing on the overlapping regions between long and medium term and between medium and short term resource allocation phases and (3.) the evolving resource allocation perspective (monetary to headcount to skillset) through these phases. Cooper et al note that for R&D product portfolio management and the Stage Gate process to work together, one can expect one of two scenarios - a gates dominated approach (where the prioritization and resource decisions are made at short term focused Stage Gates) or a portfolio reviews dominated approach (where the prioritization and resource decisions are made at the long term focused portfolio reviews). We propose that with appropriate focus given to the medium term phase, a third approach that we call a Hybrid Gates approach can exist in a "gates dominated" environment. A case study on Freescale Semiconductor was used as an empirical inquiry to gain deeper understanding on the perceived value of this approach within a real-life context. Triangulating between structured surveys, unstructured surveys, and focused interviews; we were able to show perceived value to the organization in the following areas: (1.) Enhancing the understanding of decision maker's decision and solution spaces, (2.) Clarifying strategic expressions and "stress testing" new strategies, (3.) Improving horizontal and vertical communication within the organization and (4.) Aiding in objectivity in R&D investment allocation. Furthermore, we were able to conceptually show how this approach retains the advantages of the gates dominated and portfolio dominated approaches while minimizing their respective weaknesses. This research is novel and unique as we have not found any research literature that focuses on a Hybrid Gates approach perspective or studies where the implementation of MO-ZOLP is: (1.) this large in scale and (2.) designed specifically to support a Stage Gate dominated environment. We believe that this research contributes to the practising educator and researcher by providing them with an alternative approach on R&D project portfolio management in complex organizations that are using a Stage Gate process. We also believe that this research is valuable to the practitioner by providing them with a practical process and methodology in which change management for such activities can be achieved. In addition, we assessed the on-going value added to the organization, thus linking theory to practice and finally, to outcome.
The use of multi-product plants for the production of high value goods in the process industry has already reached an impressive level and is still growing. It will be shown that capacity analysis is ...an often needed task within medium-range planning activities for multi-product plants. Restrictions due to limited supply of energy can have a considerable impact on the result of a capacity analysis and therefore need to be considered in the model. For the generation of maximum capacity schedules the combination of genetic algorithms (GA) with a commercial discrete-event simulation system is proposed. It will be shown that the production in a multi-product plant including resource restrictions can be modeled within the system. A way of coding the variables in a GA will be shown as well. A case study shows that this approach is very promising when strongly limited resources have to be considered.
A planning approach is presented for short term mode of operation in multipurpose batch plants. Planning output is given in the form of processing time windows for intermediate products. Time windows ...are established from the time profile demand of final products and raw materials availability plan input by the user. Equipment units capacity analysis is used to assure a feasible situation and an acceptable plant loading.
Coverage and capacity analysis of hybrid home networks Tinnakornsrisuphap, Peerapol; Purkayastha, Punyaslok; Mohanty, Bibhu
2014 International Conference on Computing, Networking and Communications (ICNC),
2014-Feb.
Conference Proceeding
A hybrid home network is a network consisting of hybrid devices capable of both Wi-Fi and powerline communications. We provide a comparison of coverage and capacity between hybrid, standalone Wi-Fi, ...and standalone powerline networks. We demonstrate that hybrid networks improve both the coverage and the capacity of a home network to simultaneously support high definition video streaming and mobile devices. The analysis is extended to show that the benefits of hybrid networks are amplified when multi-hop topologies are supported.
Collaborative beamforming with finite number of collaborating nodes produces sidelobes that depend on the nodes' arrangement. Sidelobes cause interference when they occur at the directions of ...unintended receivers and thus reduce the transmission rate at these receivers. Peak sidelobe minimization does not effectively minimize the overall sidelobe of a beampattern formed by collaborative beamforming. Two main contributions are highlighted in this paper. First, we proposed a new fitness function based on directivity instead of the conventional peak sidelobe. Second, we applied the genetic algorithm (GA) to reduce the sidelobe in collaborative beamforming. This proposed solution is implemented without any feedback from the unintended receiver(s). In the light of reduced sidelobe, we recorded the resultant capacity and calculated its improvement. Results showing up to 14% of capacity improvement, proving the efficacy of the proposed methodologies: the GA and the new fitness function.
Capacity analysis of satellite network, especially multilayer one, is of theoretical and practical significance for improving the network efficiency and strengthening the guaranteed ability of ...network services. However, existing solutions, which usually focus on Up/Down links (UDLs) of satellite network, without considering the characteristics of satellite network, e.g., dynamic topology, limited resources, periodicity, are not scalable for the capacity analysis of Inter-Satellite links (ISLs) of Multi-Layer Satellite Network (MLSN). In this paper, we present a capacity analysis method for MLSN based on an improved Distributed Genetic Algorithm (DGA). The improved DGA, as an intelligent optimization algorithm, is used to solve the problems of network capacity analysis. Moreover, the capacity analysis method is applied in the MLSN to analyze the network capacity and extensively evaluated. Simulation results demonstrate that the method can efficiently calculate the upper bound and lower bound of network capacity with faster convergence speed, higher searching precision and ability of avoiding premature convergence. In addition, we conclude that node failures lead to the decrease of network capacity and different constellation structures have different effects on the upper bound and lower bound of network capacity.
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