Why spatial multiplexing

The statements are just to illustrate the difference between the two techniques. Again, it is a comparative statement. I say zero, since we are not gaining anything with transmit diversity in terms of multiplexing gain. It only improves the reliability. Previous article in this series : Introduction to Multiple Antenna Systems Multiple antenna systems are the current trend in many of the wireless technologies that is essential for their performance you will even see it in your future hard disk drives as Two Dimensional Magnetic Recording TDMR technology.

Techniques for improving performance Spatial Multiplexing techniques [6] , example — BLAST [7] yields increased data rates in wireless communication links.

MIMO classification with respect to antenna configuration In MIMO jargon, communication systems are broadly categorized into four categories with respect to number of antennas in the transmitter and the receiver, as listed below. Diversity: As indicated, two fundamental resources available for a MIMO system are diversity and degrees of freedom.

Single Input Multiple Output Channel with diversity. MIMO system with diversity. Thanks Reply. Thank you very much for you response. Thank you. What about spatial multiplexing? There is no such requirement. Post your valuable comments!!! Cancel reply. This site uses cookies responsibly.

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Analytics Analytics. Analytical cookies are used to understand how visitors interact with the website. These cookies help provide information on metrics the number of visitors, bounce rate, traffic source, etc. A wireless access point uses multiple radios to enable more than one unique data stream to go between the transmitter and receiver. This increases throughput and is a common technique in order to innovate with wireless setups.

By: Justin Stoltzfus Contributor, Reviewer. By: Satish Balakrishnan. Dictionary Dictionary Term of the Day. Gorilla Glass. Techopedia Terms. Connect with us. In many MIMO systems, just two are used, but there is no reason why further antennas cannot be employed and this increases the throughput. In any case for MIMO spatial multiplexing the number of receive antennas must be equal to or greater than the number of transmit antennas.

To take advantage of the additional throughput offered, MIMO wireless systems utilise a matrix mathematical approach. Data streams t1, t2,. Then there are a variety of paths that can be used with each path having different channel properties. To enable the receiver to be able to differentiate between the different data streams it is necessary to use.

These can be represented by the properties h12, travelling from transmit antenna one to receive antenna 2 and so forth. In this way for a three transmit, three receive antenna system a matrix can be set up:. To recover the transmitted data-stream at the receiver it is necessary to perform a considerable amount of signal processing.

First the MIMO system decoder must estimate the individual channel transfer characteristic hij to determine the channel transfer matrix. Once all of this has been estimated, then the matrix [H] has been produced and the transmitted data streams can be reconstructed by multiplying the received vector with the inverse of the transfer matrix.

This process can be likened to the solving of a set of N linear simultaneous equations to reveal the values of N variables.