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We address the problem of multiuser power and bandwidth allocation for Orthogonal Frequency Division Multiple Access (OFDMA) networks employing a Type-II Hybrid Automatic Repeat reQuest (HARQ) mechanism, practical Coding and Modulation Schemes (MCSs) and Bit Interleaved Coded Modulation (BICM). The problem is formulated as minimizing the sum power required to satisfy a goodput constraint for each...
In this paper, we investigate a new power allocation scheme for a multi-user orthogonal frequency division multiplex (OFDM) system, in which two cooperative power sources (CPS) coordinately transmit their power to multiple orthogonal subchannels. In order to maximize the sum rate, a closed form solution is obtained by analytical derivation. Based on the derived solution, we present a novel joint optimal...
This paper proposes a new architecture for cooperative communication in wireless ad-hoc networks particularly suitable to emergency and safety applications. The proposed solution is characterized by the following relevant features: (a) a wireless connection between each couple of network nodes is established via multiple relays; (b) each source-to-destination link is characterized by a double string...
In this paper, we consider a two-hop orthogonal frequency division multiplexing (OFDM) relay link, and investigate the system capacity in hybrid forward (HF) relay through the power allocation (PA). The expression of the system capacity in HF relay is provided. Two situations about the power constraint are concerned, and under each situation, the selection criterion among different forwarding schemes...
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...
We study the end-to-end resource allocation in an OFDM based multi-hop network consisting of a one-dimensional chain of nodes including a source, a destination, and multiple relays. The problem is to maximize the end-to-end average transmission rate under a long-term total power constraint by adapting the transmission power on each subcarrier over each hop and the transmission time used by each hop...
This paper explores the attributes, layering models and objective functions in cross layer designs for mobile ad hoc wireless networks by taking all the statistical characteristics and constraints from the physical (PHY) layer, media access control (MAC) layer and network (NET) layer into consideration. This paper reviews the entire network optimization across all the PHY/MAC/NET layers. At the PHY...
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