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Relay-assisted cooperative network coding systems are widely investigated as an effective framework to improve the system performance in IMT-Advanced system. On the other hand, green communication issues have been paid much attention due to the large energy consumption in wireless network. In this paper, an energy-efficient resource allocation scheme is proposed for two-way relay-assisted OFDM system...
Driving security and comfort can be improved by applying Intelligent Transportation Systems (ITS) proposals. The low adoption rate of new ITS hardware and software products is slowing down the market introduction of these solutions. In this paper we present a driving safety application for smartphones based on a warning dissemination protocol called eMDR. The use of smartphones minimizes the hardware...
A subspace method for channel estimation is proposed for asymmetric antenna array systems. The so-called pilot contamination problem reported in [1] is found to be due to the linearity of channel estimation in [2]. We show that it does not occur in cellular systems with power control and power-controlled handoff when the nonlinear channel estimation method proposed in this paper is used. Power-control...
We consider fractional uplink power control in a cellular system. Interference caused to neighbouring cells is analysed in a single-slope path loss model. Closed form approximations of the average interference, the average inverse interference, and the achievable rate are derived. There exists infinitely many combinations of FPC parameters in a cell, giving rise to the same interference level at neighbouring...
It is known that a selection combining (SC) diversity receiver can offer the full diversity order of an antenna array while necessitating only a single RF chain. However, a means must be provided to continuously monitor the SNR in all branches of the array. Switched diversity schemes, such as switch-and-examine (SEC), do not have this requirement but can provide performance approaching selection diversity...
In this paper we compare the energy efficiency of different multiple antenna transmission schemes for long-range wireless networks, assuming a realistic power consumption model. We consider the downlink, between a base station and a mobile station, in which the Alamouti scheme, transmit beamforming, receive diversity, spatial multiplexing, and transmit antenna selection are compared. Our analysis...
The transmission capacity (TC) of the secondary (SR) network in cognitive radio networks (CRNs) is investigated in this paper. Mathematically, the TC of the SR network is defined as the maximum transmitter density of the SR network that satisfies the outage probability constraints of the primary (PR) network and the SR network, multiplied by the communication rate and the successful reception probability...
In recent years, vehicular ad-hoc networks (VANETs) have received increasing interests because of their promising solutions in many urban applications. VANETs are distinguished from other kinds of ad-hoc networks, such as Mobile Ad-hoc Networks (MANETs), by high mobility and reduced communications. The topology of the network is highly time-varying due to high mobility of wireless nodes, and also...
In this paper, we address the problem of traffic aggregation in capillary M2M networks. In particular, we focus on monitoring application where sensor nodes gather information from the environment (e.g. temperature, humidity, concentration of pollutants, etc) and send it to the gateway (GW). The GW then processes and retransmits the data through a cellular network to a distant application server....
In this paper physical layer network coding (PLNC) in two-phase two-way relaying networks using coded orthogonal frequency division multiplexing (OFDM) transmission is investigated. After receiving the superimposed signal from both sources, the relay estimates the XOR-based network coded signal, which is broadcast back to the sources. Assuming that the relay is equipped with multiple antennas, the...
Machine type communications (MTC) is defined as data communication among devices without the need for human interaction. With the decommissioning of legacy cellular systems, migration of MTC devices to LTE is under investigation by many operators. It is desirable that the cost of LTE MTC devices is similar to that of existing GSM devices. Several cost reduction techniques have been studied. This paper...
In this paper, we investigate the optimal power allocation and optimal precoding for a cluster of two base stations(BS) which cooperate to jointly maximize the achievable rate for two users connecting to each BS in a multi-cell processing (MCP) framework. We provide a generalized fixed point equation of the optimal precoder in the asymptotic regimes of the low- and high-snr. We introduce a new iterative...
In this letter, we investigate the outage performance of a dual-hop fixed-gain amplify-and-forward relaying systems in presence of interference at the relay.We assume the desired signal has Nakagami-m fading and the interfering signals experience independent and identically distributed (i.i.d) κ − μ and η − μ fading. We present exact and closed-form expressions for the outage probability. Then we...
For WLAN systems in which relaying is used to improve throughput performance for nodes located at the cell edge, node mobility and information collection delays can have a significant impact on the performance of a relay selection scheme. In this paper we extend our existing Markov Chain modeling framework for relay selection to allow for efficient calculation of relay policies given either mean throughput...
In this paper, we consider the problem of optimal distributed beamforming at the relay nodes of a cognitive radio (CR) network. We assume that the CR network is a cooperative relay network with amplify-and-forward (AF) relaying scheme and is composed of single-antenna source, relay and destination nodes. We further assume that the direct link between the secondary source and destination is absent...
We experimentally investigate the benefits of multi- hop networking for intra-car data aggregation under the current state-of-the-art Collection Tree Protocol (CTP). We show how this protocol actively adjusts collection routes according to channel dynamics in various practical car environments, resulting in performance gains over single-hop aggregation. Throughout our experiments, we target traditional...
In this paper, we propose a frequency domain CRS successive interference cancellation scheme for HetNet deployment in 3GPP LTE-Advanced Rel-11 systems. The proposed scheme calculates a metric value for each interfering cell. Based on the calculated metric value, the CRS interferences from dominant interfering cells are successively cancelled with adaptive channel estimation. Furthermore, two threshold...
One of the biggest problems nowadays for network operators are occurring call drops. This problem has been increasing in the last years specially since the advent of 3G. The investigation in the operator's network is very time intensive and due to the highly priced hardware only a few measurements can be done per day. In this paper we present a new methodology to investigate call drops by using mobile...
With deploying LTE (Long-Term Evolution) network operators are faced with managing up to three partly overlaying network deployments of different radio access technologies (RATs), for instance, GSM, UMTS and LTE. A concerted management of all three RATs requires self-organizing networks (SON) functionalities which have become an essential part of LTE. One prominent use case is mobility robustness...
CoMP (Coordinated Multiple Point transmission and reception) is a key technology in 3GPP LTE-A (3rd generation partnership project long term evolution advanced) which is expected to greatly improve the cell-edge throughput performance by the cooperation of multiple eNBs (evolved NodeBs). We developed a prototype system to realize CoMP JT (joint transmission) using a novel network control architecture...
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