Sharif Digital Repository

In this paper, a new scheme for adaptiva subcarrier, bit and power allocation for downlink transmission of multiuser orthogonal frequency division multiplexing (OFDM) systems is presented. An adaptive algorithm is introduced to achieve the desired bit rate and BER for QoS (quality of service) of different users in a frequency selective fading channel, while the total transmit power is minimized. The performance and complexity of the proposed scheme is also thoroughly compared with the other existing methods. As the simulation results show, the proposed algorithm outperforms all prior sub-optimum schemes, while offering comparable computational complexity. © 2003 IEEE  

Climate change as a serious environmental issue has been subjected to many management studies. Yet the issue of allocating global responsibilities to emission reduction in a reasonable way is an unconcluded challenge. Two main groups of responsibility allocation systems are production-based responsibilities (PBR) and consumption-based responsibilities (CBR). PBR takes territorial emissions within borders into account that is applied to global policy makings by the Intergovernmental Panel on Climate Change (IPCC). In contrast, CBR considers the emission transfers through international trade and allocates the responsibilities based on the goods and services being consumed by each country. Both... 

Since in the emergency service networks the length of time to attend a call is of utmost importance, it is imperative to observe guidelines in locating the service centers within a service network and allocating the demand nodes to them in a manner that service can be provided within a reasonably short period of time. So far both qualitative and quantitative models have been developed to tackle these problems. The latest models which assume a probabilistic orientation, use queuing theory notions to achieve a more suitable solution. This article attempts to apply both queuing theory and fuzzy theory to the location-allocation problem in hope of analyzing the problem in a more realistic... 

In this paper, a processor allocation mechanism for NoC-based chip multiprocessors is presented. Processor allocation is a well-known problem in parallel computer systems and aims to allocate the processing nodes of a multiprocessor to different tasks of an input application at run time. The proposed mechanism targets optimizing the on-chip communication power/latency and relies on two procedures: processor allocation and task migration. Allocation is done by a fast heuristic algorithm to allocate the free processors to the tasks of an incoming application when a new application begins execution. The task-migration algorithm is activated when some application completes execution and frees up... 

In this paper, we propose a processor allocation mechanism for run-time assignment of a set of communicating tasks of input applications onto the processing nodes of a Chip Multiprocessor (CMP), when the arrival order and execution lifetime of the input applications are not known a priori. This mechanism targets the on-chip communication and aims to reduce the power and latency of the NoC employed as the communication infrastructure. In this work, we benefit from the advantages of non-contiguous processor allocation mechanisms, by allowing the tasks of the input application mapped onto disjoint regions (sub-meshes) and then virtually connecting them by bypassing the router pipeline stages of... 

In this paper, we propose a processor allocation mechanism for run-time assignment of a set of communicating tasks of input applications onto the processing nodes of a Chip Multiprocessor (CMP), when the arrival order and execution lifetime of the input applications are not known a priori. This mechanism targets the on-chip communication and aims to reduce the power and latency of the NoC employed as the communication infrastructure. In this work, we benefit from the advantages of non-contiguous processor allocation mechanisms, by allowing the tasks of the input application mapped onto disjoint regions (sub-meshes) and then virtually connecting them by bypassing the router pipeline stages of... 

Femtocell has appeared as a solution to increase both coverage and capacity of cellular networks. However, interference problem between the macrocell and the femtocell must be solved before any deployment. In this paper, we deal with the problem of joint subband, rate, and power allocation in OFDMA based two-tier femtocell networks. It is assumed that for macrocell users, spectrum allocation is accomplished through Fractional Frequency Reuse (FFR). Our objective is to maximize the femtocell user's throughput while maintaining as little as possible reduction in the macrocell users' performance. Our proposed algorithm is decentralized, and needs to be done only when femtocell access point is... 

Multi-Facility Weber Problem (MFWP), also known as continuous location–allocation problem, entails determining the locations of a predefined number of facilities in a planar space and their related customer allocations. In this paper, we focus on a new variant of the problem known as Single-Source Capacitated MFWP (SSCMFWP). To tackle the problem efficiently and effectively, an iterative two-phase heuristic algorithm is put forward. At the phase I, we aim to determine proper locations for facilities, and during the phase II, assignment of customers to these facilities is pursued. As an alternative solution method, a simulated annealing (SA) algorithm is also proposed for carrying out the... 

In this paper, we study the resource allocation and scheduling problem for a downlink non- orthogonal multiple access (NOMA) network where the base station (BS) allocates the spectrum resources and power to the set of users. We aim to optimize the sub-channel assignment and power allocation to achieve a balance between the number of scheduled users and total sum-rate maximization. To solve the above problem, we propose a many-to-many two-sided user-subchannel matching algorithm in which the set of users and sub-channels are considered as two sets of players pursuing their own interests. The algorithm converges to a pair-wise stable matching after a limited number of iterations. Simulation... 

In this work, a bi-objective multi-facility location-allocation problem is investigated, in which the locations of the customers and their arrivals are stochastic. We first formulate the problem as a continuous location-allocation model with no constraints on the capacity of the facilities. Then, we develop an approximated discrete model in which the facilities with limited capacities can be located on a set of candidate points. The proposed model has two objective functions that are evaluated using discrete event system simulation. The first objective is to minimize the expected total time the customers spend in the system until their services begin. The time that each customer spends in... 

With technology advances and the emergence of new fabrication and VLSI technologies, current and future chip multiprocessors (CMPs) are expected to have tens to hundreds of processing elements and Gigabytes of on-chip caches, which are connected by a high bandwidth network-on-chip (NoC). Unfortunately, due to limited power budget of a computing system, specially for its processing element(s), it is impossible to keep all cores, caches, and network elements working at highest voltage level—that would resulted in dark silicon computing era, where by employing system-level or architecture-level techniques, one can keep a great portion of a CMP elements OFF (or in dim mode) to meet the power... 

As a promising solution for future indoor access networks, resource allocation in Visible light communication or LiFi networks is subject to lots of researches. An interesting approach for network algorithm design is to use some knowledge about the future of the network. With this regards, the anticipatory design may improve the performance of the system in terms of delay and throughput. This paper reviews the state-of-the-art anticipatory algorithms proposed in the literature, given different prediction capabilities. The key element that all of these algorithms share is to find an event that correlates the current actions to the performance of the network in the future. Apart from the... 

The efficient planning of search and rescue (SAR) operations is highly impactful in the disaster response phase, which offers a limited time window with a declining chance for saving trapped people. The present paper introduces a new robust decision support framework for planning SAR resource deployment in post-disaster districts. A two-stage decomposition approach is applied to formulate the problem as iterative interrelated stages of mixed-integer programming (MIP) models. The first stage presents a robust multi-period allocation model for maximizing fair and effective demand coverage in the affected districts during the entire planning horizon. It takes into account the time-sensitiveness... 

Tolerances significantly affect the assemblability of components, the product's performance, and manufacturing cost in mechanical assemblies. Despite the importance of product reliability assessment, the reliability-based tolerance design of mechanical assemblies has not been previously considered in the literature. In this paper, a novel method based on Bayesian modeling is proposed for the tolerance-reliability analysis and allocation of complex assemblies where the explicit assembly functions are difficult or impossible to extract. To reach this aim, a Bayesian model is developed for tolerance-reliability analysis. Then, a multi-objective optimization formulation is proposed for obtaining... 

The efficient planning of search and rescue (SAR) operations is highly impactful in the disaster response phase, which offers a limited time window with a declining chance for saving trapped people. The present paper introduces a new robust decision support framework for planning SAR resource deployment in post-disaster districts. A two-stage decomposition approach is applied to formulate the problem as iterative interrelated stages of mixed-integer programming (MIP) models. The first stage presents a robust multi-period allocation model for maximizing fair and effective demand coverage in the affected districts during the entire planning horizon. It takes into account the time-sensitiveness... 

We study the problem of fair allocation for indivisible goods. We use the maxmin share paradigm introduced by Budish [16] as a measure for fairness. Kurokawa, Procaccia, and Wang [36] were the first to investigate this fundamental problem in the additive setting. They show that a maxmin guarantee (1-MMS allocation) is not always possible even when the number of agents is limited to 3. While the existence of an approximation solution (e.g. a 1/2-MMS allocation) is quite straightforward, improving the guarantee becomes subtler for larger constants. Kurokawa et al. [36] provide a proof for the existence of a 2/3-MMS allocation and leave the question open for better guarantees. Our main... 

In this paper, we consider a cellular cognitive radio network that uses opportunistic spectrum access for its transmission in the downlink direction from base stations toward cognitive radio users. Since the spectrum is licensed to a primary network, proper resource management should be employed in the secondary network to protect primary users against excessive interference while providing acceptable utilization for secondary users. We use game theory to propose a distributed method for joint frequency and power allocation in the downlink of cognitive radio networks. Earlier works in this area were based on centralized optimization-based approaches, whereas our proposed method solves the...