Broadband access at 60 GHz to relieve network congestion
Although current wireless local area networks (WLAN) primarily target home and office environments, it is predicted that their high geographical density deployment will complement the wide area cellular infrastructure in the future. In the framework of the BROADWAY project, an innovative concept was proposed to offload the 5 GHz radio channels from inter-system interference by new modes in the unlicensed 59 - 65 GHz frequency band. The tight integration of 5 GHz WLAN solutions with their fully ad hoc extension at 60 GHz would guarantee nomadic terminal mobility in combination with enhanced capacity by avoiding spectrum congestion. The new radio frequency architecture inherently provides backward compatibility to HiperLAN/2 technology making use of Orthogonal frequency digital multiplexing (OFDM), a modulation method for transmitting analogue signals. The 60 GHz Hiperspot equipped with a robust multi-carrier transmission scheme bridges centralised WLANs with fully ad hoc networks and can be used to offload the 5 GHz connection for a limited time. IMST GmbH was charged with designing and evaluating the antenna concepts for the demonstrator of the BROADWAY project. A highly directive planar array of patch antenna elements operating at 60 GHz provided verified availability of high data rate for fixed terminal applications like docking stations of laptops. On the other hand, for the omni-directional dual band antenna two planar arrays were integrated for transmitting and receiving both at 5 and 60 GHz, leading to a very compact but also miniaturised design. Employing this technique can open up the road for smaller mobile terminals, which are well suited for a broad range of applications, while meeting the user expectation in terms of available throughput. The possibility of integrating more than one antenna into a mobile terminal will be explored by IMST GmbH and its partners to increase the data capacity of the radio frequency connection.