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Device-to-Device (D2D) communication underlying 5G cellular networks enable using direct communication between devices as a relay strategy for coverage extension. We consider such a D2D-relaying approach in a scenario where there are multiple candidate devices to be selected as relays. Both backhaul and D2D transmissions are performed in uplink cellular resources, and are subject to cellular uplink...
This paper considers wireless powered communication networks (WPCNs), where mobile users first harvest energy from a dedicated power station and then communicate with an information receiving station. We aim to maximize the weighted sum of user-centric energy efficiency (WSUEE) via joint time allocation and power control in both downlink and uplink. The proposed approach provides the flexibility of...
LTE uses single carrier-frequency division multiple access (SC-FDMA) scheme for the uplink transmission which limits the flexibility of the allocation process as the sub carriers assigned to a single user have to be contiguous. We propose an LTE uplink interference-aware search-tree based scheduling scheme using the high interference indicator (HII) and the overload indicator (OI) messages that are...
It is significantly important to reduce uplink energy consumption in order to prolong the battery lifetime of user equipment (UE). In this paper, an uplink energy-saving power control scheme is proposed based on Coordinated Multiple Points Reception (CoMP) in the heterogeneous cellular networks. The main idea of the proposed scheme is based on the tradeoff between the uplink transmission power and...
In wireless communication networks, transmitter power control can play an important role in various communication scenario, like power control, throughput and quality of service (QoS). It is essential to find effective means of power control point-to-point, broadcasting and multi-casting. We consider the problem of unicast or point-to point (peer to peer) communication in wireless networks in the...
Multi-Cell coordination or Coordinated Multi-Point (CoMP) schemes are seen as the next evolution of LTE-Advanced to yield a further improvement in overall system performance. In this paper, we study in detail the performance of one such CoMP scheme, namely Multi-cell coordinated scheduling (MuCCS). In our previous work, we have shown that the performance of MuCCS using a distributed "liquid cooperation...
This paper is focused on the issue of complexity and low accuracy of downlink (DL) power control in dense heterogeneous network. A novel power control algorithm based on the interference statistic properties that is accurate and results in easy-to-evaluate interference is proposed. Compared to the recent work on DL power control using complex iterations to manege interference, the proposed algorithm...
Interference due to multi-channel CR hidden terminals and edge PU receivers at link level has direct impact on performance of CR-MAC protocol. State-of-the-art research in CR-MAC propose sequential, cluster-CCC coverage for In-band and global CCC coverage for out-of-band spectrum to avoid primary (PU) and secondary (CR) hidden terminals. But, imperfect node synchronization due to per hop and group...
We consider the downlink of Cell-Free Massive MIMO systems, where a very large number of distributed access points (APs) simultaneously serve a much smaller number of users. Each AP uses local channel estimates obtained from received uplink pilots and applies conjugate beamforming to transmit data to the users. We derive a closed-form expression for the achievable rate. This expression enables us...
Self-powered, energy harvesting small cell base stations (SBS) are expected to be an integral part of next-generation wireless networks. However, due to uncertainties in harvested energy, it is necessary to adopt energy efficient power control schemes to reduce an SBSs' energy consumption and thus ensure quality-of-service (QoS) for users. Such energy-efficient design can also be done via the use...
Unlicensed LTE system holds high potential to effectively offload data traffic/video traffic from the crowded LTE networks. Listen-before-talk is generally necessary for unlicensed LTE to coexist with existing transmissions in the unlicensed band (e.g. wireless LAN). This paper studies the interaction of clear channel assessment (how hard one should listen before talk) and transmit power control (how...
In this paper, after discussing the challenges raised by the increasing density of IEEE 802.11 WLANs, we investigate a new combination of transmit power control and physical carrier sensing adaptation to leverage the spatial reuse in high density deployments. While each of these techniques when applied separately is efficient in enhancing the performance of such dense scenarios, they suffer from serious...
Pilot reuse in multiple cell Massive MIMO induces coherent inter-cell interference that does not disappear with large numbers of antennas. A simple way to mitigate pilot contamination is to use a pilot reuse factor that is greater than one, which surrounds the home cell by one or more rings of non-contaminating cells. The penalty for this measure is that training consumes an increasing fraction of...
Enabling coordination between products from different vendors is a key characteristic of the design philosophy behind future wireless communication networks. As an example, different devices may have different implementations, leading to different user experiences. A similar story emerges when devices running different physical and link layer protocols share frequencies in the same spectrum in order...
Underwater acoustic communication networks face several challenges: large propagation delays, low bandwidth and high transmission power. Recent studies exploit the large propagation delay to allow concurrent transmissions in the network. Given a suitable network geometry, it has been shown that the network throughput increases linearly with the number of nodes, provided optimal transmission schedules...
Femtocells are an integrating part of future cellular systems, where radio resource management is a challenge due to unbalanced backhaul delays and the hotspot nature of femtocells. We propose a new game theoretic framework, where the channel allocation and transmit powers evolve in a distributed manner, adapting to femtocells' topology and traffic demands. The key idea is to cast femtocells' clustering...
This work aims to improve the performance of cooperative relaying in interference-limited multihop networks. The multihop network nodes are equipped with multi-rate and continuous power control capabilities. The existing technique does not yield significant performance gains with multi-rate and power control capabilities. To obtain the achievable throughput rates, a cross-layer flow-based framework...
A distributed automatic control solution for power allocation of wireless communication networks is proposed in this paper. The objectif is to combine the best features of both conventional and opportunistic power control, namely, fairness and opportunism on the QoS provision. In a first step, the Distributed Power Control (DPC) problem is formulated as a Linear Quadratic Regulator (LQR) problem....
Device to Device (D2D) communications are an important part of next generation wireless systems, and a key technology to improve local services and overall system throughput. This paper proposes Optimized Network Coding (ONC) to boost the performance of D2D communications. ONC leverages on using network coding combined with improved scheduling to increase the throughput of D2D links. We describe the...
Cognitive radio networks are an emerging paradigm for intelligent networks to resolve the spectrum under-utilization problem, as they allow cognitive users to utilize frequency bands assigned to primary users. In this paper, we consider the transmit power control of a secondary transmitter when a primary user accesses a wireless channel through a carrier sense multiple access (CSMA) mechanism. In...
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