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In this paper, we propose centralized and distributed power allocation algorithms for a multi-user, multi relay cellular network using decode-and-forward (DF) cooperation strategy taking channel uncertainty into account. The objective is to minimize the total uplink power of the network taking each user's target data rate as the quality of service (QoS) constraint under imperfect channel state information...
Network virtualization has been recognized as a promising solution to enable the rapid deployment of customized services by building multiple Virtual Networks (VNs) on a shared substrate network. Whereas various VN embedding schemes have been proposed to allocate the substrate resources to each VN requests, little work has been done to provide backup mechanisms in case of substrate network failures...
We consider an underlay cognitive radio network, in which the cognitive users (also referred to as secondary users (SUs)) are allowed to access the licensed spectrum simultaneously with the primary users (PUs). Specifically we solve a beamforming and power allocation problem in the downlink with mixed quality-of-service (QoS) requirements where a set of SUs are required to achieve a specific signal-to-interference...
In this paper, we consider a two-way asymmetric relaying channel with unmatched traffics from two sources. Aiming at maximizing the sum rate under a minimum rate constraint, we address the optimization problem (in terms of time and power allocation) for two decode-and-forward (DF) strategies, namely, the decode-and-forward with joint modulation (DF-JM) and the decode-and-forward with network-superposition...
Relay-based cooperative transmission in cellular wireless networks has been an area of tremendous research recently. Since MIMO technique has been shown to increase the spectral efficiency significantly, relays with MIMO antennas seem to be potential candidate for future cooperative cellular system in order to achieve reliable transmission, high system throughput and extended network coverage. In...
Recently, operators have resorted to femtocell networks in order to enhance indoor coverage and quality of service since macro-antennas fail to reach these objectives. Nevertheless, they are confronted to many challenges to make a success of femtocells deployment. In this paper, we address the issue of resources allocation in femtocell networks using OFDMA technology (e.g., WiMAX, LTE). Specifically,...
By supporting advanced multimedia applications and multitasking, recent Smartphone operation systems offer great flexibility to the users but make these devices even more difficult to serve. Now, operators of cellular networks face a situation where many applications and services generate highly heterogeneous and bursty traffic patterns. To cope with this challenge, we introduce Context-Aware Resource...
In this paper, we present a novel user selection scheme for the broadcast channel (BC) using zero-forcing (ZF) precoding with optimal power control. Our scheme is based on a threshold that sets a minimum acceptable sum-rate. In order to design the threshold, we develop a new approximation of the sum-rate and derive simple design rules for the threshold with complexity constraints. We also extend the...
In this paper, an efficient rate allocation scheme to maximize the throughput in uplink multi-rate time-hopping ultra-wideband (TH-UWB) communications is proposed. This is a challenging task due to the lack of a suitable closed form expression of the multiuser interference in a multi-rate context. Moreover, an exhaustive search for the optimal solution would be too prohibitive due to the high complexity...
Long Term Evolution (LTE) is considered one of the main candidate to provide wireless broadband access to mobile users. Among main LTE characteristics, flexibility and efficiency can be guaranteed by resorting to suitable resource allocation schemes, in particular by adopting adaptive OFDM schemes. This paper proposes a novel solution to the sub-carrier allocation problem for the LTE downlink that...
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