Wireless Networks Coexistence in Unlicensed Bands

Abstract

Mobile communication networks are constantly evolving and each new generation provides considerably higher data transmission capabilities. Having in mind predictions of high cellular data traffic growth over the next few years, it is clear that the licensed band communications would have problems to support such a high bandwidth demand. One of the possible solutions to this problem is to adaptively use some additional spectrum out of the dedicated licensed band, such as the unlicensed bands. LTE-A standard introduced a new mechanism, named Carrier Aggregation, which provides the possibility to simultaneously use multiple frequency bands, such as the licensed and unlicensed bands. In order to work in an unlicensed band, LTE has to employ some new procedures that provide shared access with other systems using the same frequency band, such as WiFi. These procedures include spectrum sensing, dynamic frequency selection, as well as the coordination of the shared access. Performance measurements and the analysis of the procedures in 5 GHz frequency band will be shown in this paper. Since there is no available LTE hardware operating in 5 GHz band, it has to be made in a laboratory using the software radio approach. The description of such an experiment may be complex, and therefore we describe and propose the concept of the automatic experiment code generation. The automatic code generation is based on the semantic descriptions of experiments, and it is flexible due to the adoption of the domain and system ontologies for formal representation of the semantics of the problem.