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Rapid growth in data traffic necessitates a proportional growth and improvement in the capacity of cellular networks. A heterogeneous network in which macro cells are overlaid with small cells is a cost efficient and effective paradigm shift for increasing the network traffic capacity. Unplanned deployment of low power base stations with divergent power levels introduces new challenges in heterogeneous...
This paper presents a cluster based resource allocation scheme for allocating physical resource blocks (PRBs) in downlink of OFDMA based cellular systems. The proposed scheme includes two phases of clustering and sum rate maximization. In the first phase users are clustered by using an interference graph in a way that users in each cluster are allocated the same PRB. This interference graph helps...
Device-to-device (D2D) communications as an underlay of a LTE-A (4G) network can reduce the traffic load as well as power consumption in cellular networks by way of utilizing peer-to-peer links for users in proximity of each other. This would enable other cellular users to increment their traffic, and the aggregate traffic for all users can be significantly increased without requiring additional spectrum...
Predictions abound on the growth of mobile data traffic driven by smart phones and tablet PCs that come with an expectation of broadband Internet connectivity everywhere and a demand for high quality video. The FCC's National Broadband Plan indicated that mobile data traffic in North America would increase by roughly 20 to 45 times between 2009 and 2014, and current data suggests these numbers may...
Energy consumption in wireless communication system is rapidly increasing due to the growth in wireless multimedia access. Combating the adverse effects of excessive energy consumption demands for energy-aware system design called green communication, which has become the major focus of many researchers recently. In this paper, we propose user selection and power allocation schemes for a multi-user...
We identify relaying as one of the most effective and enabling components of the LTE-A standard. However, this standard suffers from a major weakness that results from the assumptions that the relaying nodes are static, their locations are known and their number is fixed. While these assumptions facilitate the design of the cellular system, they limit the scope of relay usability. As an alternative,...
In this paper we introduce a reliable multicast concept for Device-to-Device (D2D) communication integrated into cellular network. In addition to the introduction of the basic concept, initial simulation results are presented as well. Clustering closely located devices which have local communication needs is a feasible and efficient way of solving the increasing data traffic requirements in the future...
Opportunistic beamforming is investigated in the context of multicell LTE uplink resource allocation. A scheduling algorithm based on beam and resource block (RB) allocation with opportunistic beamforming is presented. Beams are formed in a pseudorandom fashion thus allowing users to opportunistically benefit from the antenna gain and interference rejection capabilities. Results show that enhanced...
Channel reciprocity is regarded as one of the most important advantages of TDD systems. However, the RF front-ends contribute to the channel experienced, and their TX/RX mismatches might cause reciprocity error, and thus degrade system throughput. Therefore, channel reciprocity calibration is a crucial issue. Among the existing calibration methods, Over-the-air (OTA) calibration is a promising approach...
This paper presents a study on cost/benefit analysis regarding WiMAX in Europe. The first step is the engineering process (the cellular planning to be more accurately) in which the number of base stations needed to provide coverage and to ensure the quality of service in a given environment (rural, suburban or urban) is calculated through mathematical models. Following the engineering process, and...
This paper presents a study on cost/benefit analysis regarding WiMAX in Europe. The first step is the engineering process (the cellular planning to be more accurately) in which the number of base stations needed to provide coverage and to ensure the quality of service in a given environment (rural, suburban or urban) is calculated through mathematical models. Following the engineering process, and...
We consider smart “cognitive” femtocells, that can decode the base station control channel and make decision on their transmission opportunities based on the scheduling and resource allocation of the overlaying macrocell. The operation of such femtocells is somehow reminiscent of “Type II” relays, as specified in the IEEE 802.16j standard. Under certain system assumptions, we consider the tradeoff...
Cellular base stations typically orthogonalize downlink transmissions, although this approach is not always throughput-optimal. Indeed, it can be shown that removing the orthogonality constraint (as in Superposition Coding) can provide significant benefits in some scenarios. Based on this principle, we propose a scheduling algorithm for a two-user downlink that leverages the disparity in their respective...
Cell outage management is a self-healing functionality in future mobile cellular networks, aiming to automatically detect cell or site level outages (cell outage detection) as well as to mitigate as much as possible the caused degradation of coverage, capacity and/or service quality (cell outage compensation). Cell outage compensation has a variety of control parameters (and combination thereof) at...
This paper takes into account the uncertainty of the primary users' locations and transmission power in designing an optimal downlink scheduling scheme for cognitive radio cellular networks (CogCells). Localization technique is exploited to estimate the position and transmission power of the primary user (PU) transmitting on specific channel. The objective of our scheduling scheme is to maximize the...
In this paper, a cellular optical wireless communication system based on orthogonal frequency division multiplexing (OFDM) is simulated inside an aircraft cabin. Asymmetrically clipped optical OFDM (ACO-OFDM) and direct-current-biased optical OFDM (DCO-OFDM) transmission schemes are compared in terms of throughput and cell coverage. Cellular networks with wavelength reuse factors of 1 (full reuse),...
The capacity of downlink multiple-input multiple-output (MIMO) cellular network is significantly limited by inter-cell interference (ICI), especially at the cell boundary. In this paper, we propose an ICI cancellation employing a user selection algorithm associated with CoMP-CSB, which is more practically used for cellular networks. Under the partial channel state information (CSI) and no data sharing...
Inter-cell interference (ICI) is responsible for user throughput degradation and especially for users found near cell border which additionally experience serious path-losses. Efficient methods for ICI mitigation are ICI coordination (ICIC) schemes which allocate certain resources among users in different cells. In this paper we propose a decentralized ICIC scheme in order to mitigate the ICI and...
The spread of mobile connectivity is generating major social and economic benefits around the world, while along with the rapid growth of new telecommunication technologies like mobile broadband communication and M2M (Machine-to-Machine) networks, larger number of various base stations will be employed into the network, which will greatly increase the power expense and CO2 emission. In order to degrade...
In this paper, we present a performance evaluation for six scheduling algorithms over a MIMO-OFDM based cellular system. We have selected a set of scheduling algorithms that may use information about the instantaneous channel conditions, status of transmission queues, QoS requirements or pending HARQ retransmissions. Performance evaluation is focused on average delay under different cell load conditions,...
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