Opportunism in Spectrum Sharing for Beyond 5G With Sub-6 GHz: A Concept and Its Application to Duplexing

Abstract

With the envisioned massive connectivity era, one of the challenges for 5G/Beyond 5G (B5G) wireless systems will be handling the unprecedented spectrum crunch. A potential solution has emerged in the form of spectrum sharing, which deviates from a monopolistic spectrum usage system. This paper investigates the medium access control (MAC) as a means of increasing the viability of the spectrum sharing technique. We first quantify the opportunity of spectrum access in a probabilistic manner, a method referred to as opportunistic (OP) map. Based on the OP framework, we propose a random MAC algorithm in which the access of a node is randomly determined with its own OP value. As a possible application of our OPmap based random MAC, we propose a flexible half-duplex (HD)/full-duplex (FD) communication where each pair decides the duplexing mode according to the OP values of the two pair nodes. This approach fits well with the spectrum sharing system since it enables a flexible operation for the spectrum access according to the spectrum usage level. From the numerical analysis, we validate the feasibility and verify the performance enhancements by implementing a field-programmable gate array (FPGA) based real-time prototype. We further carry out extensive 3D ray-tracing based system-level simulations on investigating the network-level performance of the proposed system. Measurements and numerical results confirm that the proposed architecture can achieve higher system throughput than conventional LTE-TDD (time division duplex) systems.INDEX TERMS Duplexing, dynamic spectrum access, dynamic spectrum management, cognitive radio, spectrum sharing, full-duplex radio, opportunistic spectrum access, wireless communication and spectrum sensing. II. SYSTEM ARCHITECTURE AND OP DETECTION WITH MAC SCHEMEThis section briefly introduces the proposed system architecture and concepts of our OP map with MAC analysis. Consider a general spectrum sharing system composed of communication nodes, spectrum sensors, and a distributed server that only provides the OP value (see Fig. 1). Deployed spectrum sensors periodically measure the interference level at their locations to check the spectrum usage level. Sensors send the measured results to the distributed server.

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