Broadband wireless LANs : a feasibility study

This dissertation treats the potentials and limitations of wireless LANs intended for the support of services as envisioned for Broadband ISDN.The treatment is based on the assumption that the transmission takes place via millimetre"wave indoor radio channels.A method is discussed for the measurement of the wideband characteristics of millimetre-wave indoor radio channels.Measurements results obtained with this method are presented.These results are used for the development of a statistical model of the millimetre-wave indoor radio channel.In addition, a deterministic channel model is developed based on Geometrical Optics.A discussion concerning the applicability, limitations and accuracy of such a model is included.Results of simulations ba.~ed on the deterministic model developed are presented.These results give an indication of the influence of the environment and antenna radiation patterns on the channel characteristics.Using the measurement results, the maximum feasible bit rate is evaluated for millimetre-wave indoor radio transmission assuming QPSK modulation.In addition, the improvement by channel equalization is examined.The evaluation includes the influence of noise, number of equalizer taps, antenna diversity and antenna directivity pattern.It is shown in which way efficient, reliable and flexible information transfer can be achieved in broadband wireless LANs on the basis of the Asynchronous Transfer Mode.In this context a contention-free multi-access protocol is proposed.