Space-time open architectures for broadband wireless data communications: above the log2(1+SNR) bit/sec/Hz barrier

The creation of multiple channels (sharing the same time-frequency region) between a transmitter and a receiver can be achieved by sampling the wavefield space with respect to the spatial domain. The wavefield space is the signal space spanned by the channel parameters which characterize the multipath fading environment. Using this basic intuition it is possible to reliably transmit data at rates exceeding the famous Shannonian spectral efficiency of Log₂(1+SNR) bit/sec/Hz where the SNR is the signal-to-noise ratio over the bandwidth occupied by the signal. This exciting possibility has generated significant interest in the communications community. However, it is not, clear at this point how a realistic and cost-effective radio could take advantage of such an enhancement. WJ Communications has invested significantly in the research of this subject and sponsored the study of a new transmission scheme, STREAM_TM, [Spatial Transmission with Radio Enhanced Adaptive Modulation] able to achieve very high speed bandwidth-efficient wireless data communications in arbitrary environment: outdoor/indoor, mobile/fixed, line-of-sight/obstructed. We describe here the general ideas of the technology and show the results of the first hardware prototype which has no counterpart currently in industry in terms of scaleability, cost, performance