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Spectrum sensing is a fundamental feature of cognitive radio technologies facilitating detection and localization of spectrum opportunities. Combined with centralized database storage, it fosters reliable spatial spectrum measurements and Radio Environmental Maps (REMs) construction that can provide an accurate insight in the spectrum utilization over time, space and frequency. The spectrum sensing...
Two-tier femtocell networks, which comprise macro-cells underlaid with short range femtocells, are under intensive study due to their improved indoor coverage and data rate advantages as compared to conventional single-tier macrocellular networks. Nevertheless, the implementation of two-tier networks with universal frequency reuse causes severe cross-tier interference from the femtocells to the macrocellular...
In cellular systems, Fractional Frequency Reuse (FFR) partitions each cell into two regions; inner region and outer region and allocates different frequency band to each region. Since the users at the inner region are less exposed to inter-cell interference, the frequency resources in each inner region can be universally used. Based on this frequency band allocation, FFR may reduce channel interference...
An inter-cell interference (ICI) problem between co-channel BSs has been one of main challenging research issues in downlink cellular networks. Fractional frequency reuse (FFR) and BS cooperation are useful techniques to manage the ICI problem. By combining the BS cooperation and FFR techniques, we propose to determine an efficient cooperation mode and the type of subchannels, i.e., reusable subchannels...
In this paper, by exploiting the availability of multiple cellular radio access networks (RANs), we propose a novel two-level cooperative access network framework for superior energy efficiency. Geographically co-located RANs mutually cooperate each other through the combined use of base transceiver station (BTS) level intranetwork cooperation and RAN level internetwork cooperation. By jointly applying...
In this paper, we propose a hybrid division cooperative transmission (HDCT) scheme for system throughput enhancement in enterprise femtocell systems. In HDCT scheme, a cooperative transmission (CT) scheme is applied to user equipments (UEs) located at the edge of a serving femtocell base station (fBS), whereas conventional scheme is applied to UEs located near the fBS. In the zone where CT is applied,...
Technological advancements have made it possible to use information associated with a mobile's location to form new computing and services. One concern with these emerging location-based services (LBS) is their ability to provide security while remaining reliable and accurate. In this paper, we focus on securing Mobile Location-based Services (MLBS), where certain goods or services are provided by...
In the LTE networks, the multicast services can be transmitted by single frequency network (SFN) mode and point-to-multipoint (PTM) mode, and the unicast services are delivered with point-to-point (PTP) mode. To avoid the network congestion in the LTE networks with the multicast and unicast mixed services, an analytic hierarchy process (AHP) in load balancing is proposed to minimize the demanded radio...
In this paper, we propose a new cell architecture for the orthogonal frequency division multiple access (OFDMA) systems by jointly taking frequency allocation scheme (FAS) and cooperative relay strategy into consideration. To serve the mobile stations (MSs) in the inner zone and relay stations (RSs) in the outer zone, a larger portion of frequency spectrum is allocated to the central base station...
In this paper, we propose an energy saving solution for mobile systems based upon dynamic cell configuration for different scenarios. To characterize the optimal energy savings of base stations, we propose an active cell rotating scheme to control the number of active cells with regard to different work patterns switching among three states (active, receive and sleep). A recovery mechanism is enabled...
This research proposes a new architecture for the inter-connectivity between UEs running on the LTE infrastructure participating in an Application Layer Multicast-based distributed conference. The main contribution is that the proposal replaces the standard centralized architecture of the IMS-based conference with a more robust solution utilizing intelligence and computational capacity of LTE's eNodeBs...
The link delivery probability in a wireless mesh network is most accurately determined only by experiment, as it depends on many factors, including environment characteristics, transmission power, distance between transmitter and receiver, channel fading, and background noise. This paper provides an insightful framework for characterizing link performance results produced at Qatar University (QU)...
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