Plextek designs wireless LAN adaptive antenna for Ofcom's SES

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Press Release

Plextek designs wireless LAN adaptive antenna for Ofcom's SES

Demonstrator built to research the benefits of a smart antenna approach at 5GHz

Plextek has designed and built a 5GHz wireless LAN adaptive antenna demonstrator for the communications industries regulator Ofcom, as part of a consortium led by Vector Fields Ltd. The project was funded under Ofcom’s Spectrum Efficiency Scheme (SES), which is targeted towards supporting Ofcom's regulatory function to ensure the optimal use of the electromagnetic spectrum. Plextek’s antenna is being used to research the benefits of a smart antenna approach to wireless communication applications operating at 5GHz, within the constraints of limited antenna size and cost. The antenna is aimed at providing improved range and selective nulling of interference, for greater capacity in the desk/mobile PC environment.

The demonstrator employs an array of four elements, each followed by a downconverter and I/Q detection stage. The type of element and array geometry can be chosen to suit the installation, but at present a square array of dipole elements is used, providing full 360° coverage.

Adaptation is performed by applying phase and amplitude weighting to each element using an LMS (Least Mean Squares) algorithm. This reduces signal error and allows interfering signals and potentially destructive multipath to be nulled. The resulting beam shape provides the best available performance given the constraints of the antenna configuration chosen and propagation path characteristics. This approach complements other techniques, such as simple diversity and full Multiple-Input, Multiple-Output (MIMO), by offering potential gain in both line of sight and multipath environments.

The antenna was presented and discussed as part of the Ofcom R&D Symposium in November 2005 and was then demonstrated at Ofcom’s SES Workshop on Smart Antennas, which was hosted by Plextek in December 2005.

Issued 08/05/2006