To better understand how MIMAX can bring improvements within the wireless world we dwell briefly on what are the innovations introduced by MIMAX in a conventional MIMO architecture. Figure 1 shows the conventional MIMO architecture, where each antenna is equipped with its own front end and a base radio band. Only following the production of reports made by these blocks the signal of each antenna is recombined into a single data stream, with those from other antennas present on the array.

In Figure 2 instead illustrates very schematically the solution MIMAX. The data stream from each antenna is first multiplexed with the signals from the other antennas of the array and then processed as a single signal from a single front end and a single base band.

Figure 1 Standard MIMO configuration		Figure 2 MIMAX MIMO configuration

MIMO systems are currently on the market, but their efficiency is far from meeting the promises of reliability and high capacity transmission. The most striking example is given by the evaluations that can be found on some websites (Tom’s hardware) which compares the 802.11n MIMO (still draft version) with SISO 802.11g technology, the results also due to high interference problems is that they see the lack of interoperability of 802.11g far superior to 802.11n.

Some of the reasons why the MIMO technology has not yet set completely on the technology are to be found at the SISO signal processing. MIMO systems currently used:

Smart Antennas (Smart Antennas), able to choose and select the path to less interference
Phased Array, able to improve the performace of the radio channel only changing the signal phase
Adaptive antennas (Adaptive Antenna System), phase and amplitude are varied to increase the performance of channel

Although on paper a very efficient and simple implementation in the real world, these solutions appear to be very costly and unrealizable for commercial systems, going to set up downstream of the radio front end, within the base band of each antenna. The first consequence of this choice is an increase in cost of proportional to the number of antennas that make up the final system.

A long series of analysis and studies of University of Dresden and the University of Cantabria has given rise to the possibility of improving the performance of a MIMO system based on the concept of adaptive antennas, moving the functionality to adjust the signal from base band at the front end radio. What is immediately obvious and can be easily inferred from comparison of Figure 3 and Figure 4 is that MIMAX we will have a single front end and a single base radio band in which feed into a single radio signal created by the combined input of all signals from individual antennas.

Figure 3 Conventional approach performing adaptive combining in the baseband		Figure 2 MIMAX approach employing adaptive antenna combining in the radio frontend