Efficient use of the radio spectrum is a necessity for future wireless systems. Cognitive Radio (CR) systems promise large inc reases in spectral efficiency. An important design constraint for systems is understanding of the current use of frequency bands which may be used by future CR systems. This paper describes a set of spectrum occupancy measurements performed in Hull, UK, in November 2012...

Cognitive radio has been proposed as an innovative and effective technology to exploit the efficient reuse of the precious radio spectrum. In spectrum sensing which is a crucial step in cognitive radio networks, an adequate sensing range needs to be defined to prevent the hidden transmitter/receiver problems. Moreover, a secondary user may have unreliable detection of the existent primary users...

In this paper, throughput performance of the access links (i.e., base station to mobile station and relay station to mobile station) is analyzed for the two-hop IEEE 802.16j wireless relay networks with asymmetrical topology. In specific, three frequency reuse schemes are proposed to improve the spectrum efficiency of the access links: (1) an isolation band based frequency reuse scheme (IBFRS) ...

The last decade has seen a tremendous growth in wireless networks, resulting in a proportionate increase in demand for spectrum. But spectrum is limited, which has led to the design of techniques such as Cognitive Radio Technology [2], for using the available spectrum more efficiently. In Cognitive Radio Networks (CRNs), there are two types of spectrum users: (i) a primary user who leases a cer...

We address an important communication issue in wireless cellular networks that utilize Frequency Division Multiplexing (FDM) technology. In such networks, many users within the same geographical region (cell) can communicate simultaneously with other users of the network using distinct frequencies. The spectrum of the available frequencies is limited; thus, efficient solutions to the call contr...

Plan generalizations are of considerable importance in improving planning performance through reuse. In this paper, we provide a unified framework for analytic (non-inductive) plan generalization based on explanation of plan correctness with respect to modal truth criteria. Within this framework, we explore a large spectrum of generalizations based on the type of constraints on the plan that ar...

Piazza leonardo Da Vinci, 32 20133 Milano, ITALY fax: +39-2-2399-3413; e-mail: last [email protected] Abstract— Recently, a new method for achieving spectrum reuse in cellular systems, called Capture-Division Packetized Access (CDPA), has been introduced. The method uses a single frequency in all cells but, unlike CDMA, allows each transmitter to access the full bandwidth. Practically, the CD...

Cellular systems provide two-way voice and data communication with regional, national, or international coverage. Cellular systems were initially designed for mobile terminals inside vehicles with antennas mounted on the vehicle roof. Today these systems have evolved to support lightweight handled mobile terminals operating inside and outside buildings at both pedestrian and vehicle speeds. The...

Spectrum is a limited and precious resource in wireless communications. Effective spectrum utilization becomes more and more important because of the expeditious increase of demand for wireless communications. In principle, the dual-polarization frequency reuse system, which employs two orthogonally polarized electromagnetic waves to carry information, can double the system capacity. However, t...