A flexible architecture for future wireless local area networks

This paper reports on the activities at IMEC that will lead to a 100Mb/s indoor communication system based on multi-carrier modulation. The goal is to build a wireless local area network, which can compete with today’s wired solutions in terms of cost and performance. It is shown how a dedicated ASIC architecture implements an OFDM modem with 256 carriers that allows transmission of complex symbols (QPSK, 16 QAM) at 50Mbaud/s. It is also demonstrated how adaptive turbo-decoding allows operation close to the Shannon limit and how it can be used to provide quality of service. Adaptive loading of the carriers provides a further capacity enhancement. A gain of 6.5dB in the required signal to noise ratio can be observed compared to standard non-adaptive schemes. Finally, an SDMA scheme with full channel characterization is proposed in order to increase the channel capacity even further. It turns out that even with short training sequences a substantial capacity improvement can be observed.