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The persistent awareness of dynamic links quality is of critical importance to shared access systems, e.g., promoting sensing accuracy or even enabling seamless sharing, which remains yet as a challenging task. In this paper, we consider the shared access in heterogeneous small-cells, which are likely to be the main infrastructure components by utilizing the carrier aggregation (CA) scheme, potentially combining both licensed and unlicensed bands. We suggest a promising sensing scheme, which permits the simultaneous assessment of multiple links quality when detecting vacant spectrum, and hence is able to solve the long-standing hidden terminal problem. We incorporate an additional objective of acquiring dynamic link state information of multiple incumbent transmitters/receivers, and thereby, structure spectrum sensing as a mixed classification and estimation problem. The main challenge is that multiple channels may become similar with each other, and existing joint estimation schemes are unable to distinguish which incumbent is active and what its associated channel state is. To address this indistinguishable problem and alleviate the error propagation in recursive estimations, a novel alternating Bernoulli filtering algorithm is proposed. By fully exploiting the group transitional behavior of incumbents, a multiple-chains inference framework is developed. Numerical simulations validate our new scheme. Occupancy states of multiple incumbents can be identified accurately, by tracking their links quality and exploiting the underlying dynamics, which lays the foundation for more effective shared access. [ABSTRACT FROM AUTHOR]

This work focuses on the implementation of dynamic spectrum access in a scenario where the existing wireless infrastructure is shared by a secondary cellular system. We study the optimization of the physical antenna configuration of the secondary-system base stations, assuming that these antennas are deployed at the transmitter sites of a primary broadcast network. Specifically, we maximize the throughput of a secondary network (SN) operating within a primary network (PN) by finding the optimal antenna height and vertical tilt for the SN base stations. This optimization is constrained by the physical restrictions in the deployment site and by the maximum allowed interference to the PN. We show that this optimization provides significant gain in the cell throughput of the SN while reducing interference toward users of the primary system. As a case study, we design an optimized configuration for the SN antenna when the SN operates as a dedicated communication link for a regional transport system. To this end, field measurement data gathered in collaboration with a regional transport authority are used to calibrate the presented modeling method. [ABSTRACT FROM AUTHOR]