Development of an antenna system for a relay-based wireless network. Simulation and measurement of antenna systems for relay-based wireless network, covering the backhaul and access links and applying beam forming technology.

摘要

The proliferation of modern wireless networks increases demand for high capacity andudthroughput in order to provide faster, more robust, efficient and broadband services to end users.udMobile WiMAX and LTE are examples of such networks in which for some cases they haveudexposed limited connectivity due to harsh environment. Relay stations are preferred toudovercome problems of weak or no access for such network devices, that are placed in specificudpositions to maintain high quality of data transfer at low cost and provide the requiredudconnectivity anywhere anytime. These stations should be equipped with an antenna systemudcapable of establishing communication between base station (backhaul link) and end usersud(access link).udThis thesis focuses on the design and development of a new antenna system that is suitable for audrelay-based wireless network. Planar geometries of microstrip patch antennas are utilized. Theudantenna system comprises two antenna modules: a new design of a single antenna for accessudlink and a new design of an antenna array for backhaul link realization. Both antennaudspecifications are compatible with the IEEE802.16j protocol standard. Hence, relay stationudshould be capable of pointing its radiation pattern to the base station antenna, thus to achieve theuddesired radiation pattern of the relay station, a new beam-forming module is proposed, designedudand developed to generate the proper radiation pattern. The beam-forming module incorporatinguddigital phase shifters and attenuator chips is fabricated and tested. The optimization processudusing the Least Mean Square (LMS) algorithm is considered in this study to assign the properudphase and amplitude that is necessary to each radiation element excitation current, to produceudthe desired steered radiation pattern.udA comprehensive study on the coupling effects for several relative positions between two newudbackhaul and access link antenna elements is performed. Two new antenna configurations forudcoupling reduction are tested and the simulated and measured results in terms of antennaudradiation performances were compared and commented.