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Resource allocation in the context of OFDMA-based systems is challenging, given a combinatorial nature of the problem. In the context of IEEE 802.16 systems this problem is further exacerbated by additional constraints that are faced with its two dimensional frame nature. The main challenges associated with resource allocation in these systems are: mapping the allocated bandwidth resources to users...
Increasing demand by wireless communication applications for spectrum bands predominately occupied by radar applications has led to challenging resource allocation issues in the congested spectrum environment. A new resource allocation scheme based on Marginal Fisher's Information (MFI), is proposed to address the issue of spectrum congestion. Using MFI, which in some cases is identical to integrated...
To prolong the network lifetime, the energy usage of the nodes must be balanced in cooperative orthogonal frequency division multiplexing(OFDM) system with decode-and-forward(DF) protocol. In this paper, the system objective is minimize the total energy cost of the source and the relay. Then optimal resource allocation method based on dual decomposition is presented to resolve the system model. Simulations...
The results of development of a mathematical model for time-frequency resource allocation in the LTE technology downlink using Resource Allocation Type 1 are given. Using the proposed model allows taking into account the technological features of the LTE downlink (splitting the resource blocks into subsets, allocation of RB of only one subset to user equipment), as well as territorial remoteness of...
A fast algorithm is proposed to tackle the optimal power allocation problem for orthogonal frequency division multiplexing (OFDM)-based cognitive radio networks, where the key is to replace the Newton step with O(N^3) complexity in the barrier method by a procedure with approximate linear complexity developed based on the structure of the optimization problem. Simulation results validate that our...
In this paper, we consider a two-phase traffic-aware adaptive resource allocation (T-ARA) scheme to mitigate inter-femtocell interference in dense-deployed femtocell environments for LTE system. The proposed scheme consists of the long period allocation (LPA) strategy and the short period allocation (SPA) strategy. The quasi orthogonal bandwidth is assigned to femtocell in the LPA strategy to suppress...
In this paper, an energy efficient adaptive modulation scheme is proposed for a wireless cognitive radio ad hoc network, where each node is equipped with cognitive radio and the network is an OFDMA system operating on time slots. In each slot, the users with new traffic demand will sense the spectrum and locate the available subcarrier set. Then they choose subcarriers with favorable channel condition...
We propose a novel distributed cross-layer optimization approach for cognitive radio wireless networks. A cognitive radio is a wireless device that is capable of sensing the prevailing environmental conditions and automatically adapting its operating parameters in order to enhance the performance of both the system and potentially the whole network. Given the lack of a centralized intelligence to...
Some communication applications, like multimedia, deliver data of different importance classes allowing unequal error protection (UEP) levels. In this paper, a multiple-input multiple-output (MIMO) system using orthogonal frequency division multiplexing (OFDM) is considered with a new UEP bit-loading algorithm based on the non-UEP algorithm by Chow, Cioffi, and Bingham. In the proposed bit-loading...
This paper investigates effects of pilot assisted channel estimation on dynamic resource allocation in a multiuser orthogonal frequency division multiplexing (OFDM) system. The channel estimation is done in each OFDM symbol through least-squared error (LSE) or minimum mean-squared error (MMSE) algorithm. The performance of each of these algorithms is evaluated through computer simulations. The maximal...
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