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This paper presents novel techniques to achieve high-rate ultrasonic communications through thick metallic barriers utilizing ultrasound and provides a characterization and analysis of a 7 × 7 MIMO-OFDM acoustic-electric channel array and determines that, due to unique channel properties yielding well-conditioned channel gain matrices, a slowly adaptive crosstalk mitigation structure achieves near-optimal...
In mixed-criticality systems, resource management services are required to recognize and fulfill system wide high-level constraints, e.g., end-to-end deadlines. This is not possible through individual resources in isolation. Instead, a system-wide view is necessary which requires system-wide decisions. In the European FP7 project DREAMS, services for system-wide adaptability of mixed-criticality applications...
Device-to-device (D2D) proximity discovery enables spectral reuse via D2D communications as well as a range of innovative proximity services, such as enhanced social networking and location services. To develop a scalable discovery mechanism, signals transmitted by geographically disparate devices should not differ drastically in their received power at each monitoring device. Discovery schemes are...
A multi-tier architecture consisting of a macrocell overlaid with small cells, e.g., pico base station (BS), with provision of relays and device-to-device (D2D) communication is needed to satisfy the quality-of-service (QoS) requirements in a joint spectrum and energy efficient manner for the future Fifth generation (5G) networks. D2D communication enables the users located in close proximity to each...
In the Long Term Evolution (LTE) based device-to-device (D2D) communication systems, there are two resource access modes, i.e., eNB scheduled and random access. The eNB scheduled resource access gives flexibility to eNB with additional signalling overhead. The random access scheme is simple without the eNB control but has the drawback of data collision. In this paper, we propose a collision-aware...
This paper proposes an efficient spectrum manage scheme to fulfill environment-friendly and spectrum-efficient communication for underwater cognitive acoustic networks (UCANs). Due to the frequency-dependent attenuation, the available communication frequencies in water are severely limited. Nevertheless, this precious resource is still underutilized. In this paper, the problem of multiple cognitive...
Cooperative transmissions allow fast and reliable communication between user equipment (UE) and base stations (BSs) in radio access networks. Selecting which base stations cooperate is important to keep both effective radiated power (ERP) and outage probability low.
In order to fully exploit the high speed broadband multimedia services, prolonging the battery life of user equipment (UE) is critical from user's perspective, especially for the smartphone users. A collaborative mobile cloud (CMC), which consists of several UEs offers one potential solution for reducing the energy consumption at the terminal side. In this paper, an OFDMA mobile cloud system with...
Interference alignment (IA) is a promising technique for interference management in cognitive radio (CR) networks. However, the sum rate may fall short of the theoretical maximum especially at low signal-to-noise ratio (SNR). Moreover, in most of the previous works, energy efficiency (EE) aspect is largely ignored. In this paper, energy-efficient power allocation (PA) and transmission-mode adaptation...
This paper intends to adopt interference alignment (IA) for improving the energy efficiency (EE) of both the device-to-device (D2D) and cellular links in a D2D multiple-input and multiple-output (MIMO) downlink underlaying cellular network. Due to the strong cross-tier interference, the EE optimization problem becomes NP-hard and computationally difficult to solve. IA is implemented firstly to mitigate...
This paper analyzes the transmission capacity of D2D (Device-to-Device) network in cellular and D2D heterogeneous networks(HetNets) with cellular users (CeUEs) assisted. The D2D network capacity can be enhanced by allocating a part of CeUE transmission power to assist D2D communication. By utilizing stochastic geometry, we first model the HetNets by homogeneous Poisson point process (HPPP). Secondly,...
Device-to-Device (D2D) communication is a new technology enabling devices to communicate directly with each other which differs from the traditional cellular systems relayed by eNB. D2D is a promising technique that is expected to provide efficient utilization of the available wireless spectrum. However, as D2D communication reuses resource of cellular networks, it will be interfered by cellular users...
This paper addresses the resource allocation problem in collaborative relay-assisted OFDMA networks. Recent works on the subject have mainly considered symmetric source-to-relay and relay-to-destination resource allocations, which limits the achievable gains through relaying. In this paper our focus is two-fold. Firstly, we consider the problem of asymmetric radio resource allocation, where the objective...
This paper considers the problem of out-of-band failure localization in all-optical mesh networks using bidirectional monitoring trails (bm-trails) for localizing any shared risk link group (SRLG) failure. We firstly prove NP-completeness for the problem of unambiguous failure localization (UFL) under the considered SRLG failure scenario with the minimum number of bm-trails. Next, a necessary and...
This paper discusses performance analysis and provides an optimal resource allocation for multiple-input multiple-output orthogonal frequency division multiple access (MIMO-OFDMA) uplink system. The performance of the system is evaluated over Rician fading channels considering the effect of carrier frequency offset (CFO) and assuming channel state information (CSI) is known to the receivers. Moreover...
We investigate the problem of finding minimum-distortion policies for streaming delay-sensitive but distortion-tolerant data. We consider cross-layer approaches which exploit the coupling between presentation and transport layers. We make the natural assumption that the distortion function is convex and decreasing. We focus on a single source-destination pair and analytically find the optimum transmission...
In this paper, we propose a robust STBC transmission scheme to combat the timing synchronization errors over frequency-selective multiple-access channels. First, the equivalent channel model in the presence of timing synchronization errors is derived and we find that the synchronization errors result in an equivalent channel model with larger number of correlated channel taps. Based on this correlated...
Some communication applications, like multimedia, deliver data of different importance classes allowing unequal error protection (UEP) levels. In this paper, a multiple-input multiple-output (MIMO) system using orthogonal frequency division multiplexing (OFDM) is considered with a new UEP bit-loading algorithm based on the non-UEP algorithm by Chow, Cioffi, and Bingham. In the proposed bit-loading...
In this paper we present an algorithm, based on power management of access points (AP), to reduce congestion in wireless local area networks (WLANs). The algorithm finds the most congested access point (MCAP) and adjusts its transmitted power in discrete steps and determines the optimal userspsila assignment such that an optimal load distribution is achieved. Results show that the algorithm is capable...
We characterize the total generalized squared correlation (TGSC) for a given signature sequence set used in uplink synchronous code division multiple access (S-CDMA) when channel state information is known perfectly at both transmitter and receiver. We give a definition of the TGSC based on the eigenvalues of Gram matrix associated to signature sequences set for multipath channels in the presence...
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