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The paper investigates the use of Radio Environment Maps (REMs) as a tool for Interference Management (IM) in two-tier cellular networks comprising macro- and femto-cells. The REMs are databases that provide, through different instances distributed over network elements, a variety of network- and user-related context information for improving IM and Radio Resource Management (RRM) procedures. In this...
As plug-and-play devices, femtocells are expected to be self-managed, empowered by self-organization functionalities. This paper presents a Self-organizing networks (SON) process for off-loading macrocell traffic towards Open Subscriber Group (OSG) femtocells. The off-loading process comprises two SON functionalities: the first configures the femtocell transmitted pilot power, which depends on the...
We investigate the performance of a multiuser downlink access scheme based on a post-selection switch and examine algorithm. The studied scheme sequentially switches over the users that experience independent and non-identically distributed fading conditions, and selects a single user with an acceptable channel quality as compared to a pre-selected signal-to-noise ratio (SNR) threshold. If no one...
Fair and efficient subcarrier assignment for an infrastructure-based cellular OFDMA network is a challenging problem due to interferences from neighboring cells. In this paper, we investigate this problem using potential game theory, where the utility function adopted is meant for minimizing the co-channel interferences among different players. Each of these players is considered to be a cell with...
In cognitive radio (CR), spectrum sensing plays a fundamental and critical role. This paper deals with the issue of spectrum sensing in a distributed CR network, and proposes a novel relay based cooperative spectrum sensing method, which makes one secondary user (SU) with higher signal-to-noise ratio spend part of its sensing time acting as the relay node. Different from conventional relay based methods,...
Implementing incremental relaying in a practical system is not a trivial task because it requires the destination node to provide feedback on success or failure of a transmission. In practice, the feedback may be affected by propagation impairments and collisions. In this case, the relay and the source should coordinate among themselves in the absence of perfect feedback information such that packet...
An OFDM based cognitive radio (CR) network is considered in this paper. The goal is to maximize the total sum rate of the CR system while ensuring that no excessive interference is induced to the primary system. The optimal scheme adopts the dual decomposition technique and in order to reduce the computational complexity of the optimal scheme, a greedy suboptimal algorithm is proposed. Selected numerical...
In this paper, we investigate spectrum sharing and multiple access problems for the high-rate ultra-wideband (UWB) systems. Based on the use of the linear precoded orthogonal frequency division multiplexing (LP-OFDM) proposed as an evolution of the well known multi-band OFDM (MB-OFDM) solution supported by the WiMedia Alliance for future high-rate UWB systems, the objective of this paper is to study...
Rate adaptation, which adapts transmission bit rate according to current wireless link conditions, is a fundamental mechanism used by link-layer protocols to improve the performance of 802.11 wireless access networks in terms of throughput. However, rate adaptation faces to severe challenges due to more and more congested and dynamic wireless links. In this paper, we design a hybrid rate adaptation...
Coordinated Multi-Point (CoMP) transmission schemes can provide large spectral efficiency gains in cellular networks. Because of the coordination among neighbor basestations, the planning interval for resource allocation with CoMP is longer than for uncoordinated local transmission modes. Especially for bursty data traffic, this planning interval might be too long to keep up with changes in offered...
In this paper, we present two novel Resource Allocation (RA) strategies based on the Signal-to-Leakage-plus-Noise-Ratio (SLNR) for the downlink (DL) of Coordinated Multi Point (CoMP) transmission in LTE-Advanced (LTE-A) system. The proposed RA strategies select the UEs that can efficiently share the same Resource Block (RB) without degrading the overall throughput by using the SLNR metric. In addition,...
In this paper we present a cooperative medium access control (MAC) protocol that is designed for a physical layer that can decode interfering transmissions in distributed wireless networks. The proposed protocol pro-actively enforces two independent packet transmissions to interfere in a controlled and cooperative manner with the help of a relay. To enable distributed, uncoordinated, and adaptive...
In the literature, cooperative relaying and network coding have been used separately in improving performance of wireless MAC protocols. In this paper, we propose a novel scheme that combines both cooperative relaying and network coding for further performance improvement. The proposed scheme considers two challenges of network-coded cooperative MAC operating in a realistic wireless network. First,...
Heterogeneous networks (HetNets) are expected to be one of the major performance enhancement enablers of LTE-Advanced. Due to significantly challenging interference scenarios, enhanced inter-cell interference coordination (eICIC) based on almost blank subframes (ABS) is the key technology enabler that makes HetNets a reality. The key factor determining the gain of ABS-based eICIC is the configured...
In this paper we propose a novel resource allocation scheme to achieve a balanced performance improvement for all users in a LTE network subject to inter-cell interference. In the proposed scheme the resource allocation process is implemented in two steps. In the first step interference coordination and scheduling are first conducted in a global manner to prevent cell-edge users from mutual interference...
Cooperative communication, which utilizes neighboring nodes to relay the overhearing information, has been employed as an effective technique to deal with the channel fading and to improve the network performances. And network coding, which combines several packets together for transmission, is very helpful to reduce the redundancy at the network and to increase the overall throughput. Introducing...
A low-complexity user pairing algorithm for the broadcast phase of the XOR-based network coding is presented. The proposed scheme achieves the same spectral efficiency as an exhaustive search approach based on maximizing the sum-rate when network coding is utilized for all transmissions. The proposed scheme is further complemented with an adaptive switch, per user pair, between network coding and...
This paper considers a multicast scenario and compares the average reception quality obtained when combining multiple description coding (MDC) and network coding (NC). Plain (single description) network coding (NC-SDC) serves as reference. In the considered scenario, a single source is multicast to several receivers with various channel conditions. Contrary to a NC-SDC scheme, unable to recover the...
In today's wireless communication systems, automatic repeat request (ARQ) is implemented at the MAC layer in order to retransmit packets that have been erroneously transmitted at the physical (PHY) layer. Following a joint PHY-MAC design, information provided by the ARQ scheme can be exploited at the PHY layer in order to improve the system's performance. This paper extends the work presented in [1]...
In this paper, we consider a channel-aware ALOHA network in which users have the knowledge of their own channel state information (CSI) and exploit this decentralized CSI by utilizing CSI-based transmission schemes. The system throughput is investigated with multi-region transmission schemes under the signal-to-interference-plus-noise ratio (SINR) capture model. We discover that the two-region transmission...
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