Information about MIMO technology

[alexandr22061986]

Can anybody explain me this technology? How we can transfer several data streams using same frequency band? And how than we can demodulate all this received signals? The main question is how providing an ortogonality of this signals?

Thank you

 

[k.sridhar]

Re: MIMO help

hi first of all you should think this process in a packet based transmission, means our whole data is going t5o be send in the form of packets , each packet consists of data carriers ,pilot carriers for channel estimation and equalisation purposes, guard bands , time gaps and mmore importantly preamble(for synchronization purposes) and some mappings to describe the format of the packet.

now OFDM in the sence we transmit data carriers in a packet symbol on the carriers having integral maltiples of the fundamental frequency which by them self orthognal (because of integral maltiples of the fundamental frequency) which can be easily occured by IFFT of the time domian carriers in the packet, this all carriers are considered to be in one band orthogonally. packet contains many symbels and each symbol will be seperated in time domain and carriers in the symbol will be in frequency domain. now you should have got the whole idea of the this transmission, i

i didn't get what particularly u want on mimo

 

[andrewmacgill]

Re: MIMO help

consider it like a system of equations e.g., for 2x2 MIMO, we get two equations where the LHS represents the o/p at each of the receivers in terms of both the transmitters. Now the coefficients of the Tx signals on the RHS are given by the channel amplitude and phase. Assuming independent fading between each pair of antennas, we get a system of linear equations which can be solved using zero-forcing, mmse or ML techniques. In short, the extra spatial dimensions and the independent fading between the antennas provides us with the orthogonality. read any of the books on mimo available on this forum for further detials.

 

[mkhan]

Re: MIMO help

Hi,

Can anybody explain me this technology? How we can transfer several data streams using same frequency band? And how than we can demodulate all this received signals? The main question is how providing an ortogonality of this signals?

Thank you

I would say you need to read few articles on this and then you would understand it in a very good and authenticated way. I would suggest the followings:

1. Famous paper of G.J.Foschini et al on MIMO "Layered Space-Time Architecture for Wireless Communication in a Fading Environment When
Using Multi-Element Antennas"

2. Same author "On the Limits of Wireless Communications in a Fading Environment When Using Multiple
Antennas"

3. Very Good Book by A. Paulraj et al "Introduction to space time wireless communications" Cambridge Uni Press.

4. Another Excellent Book "fundamentals of wireless communications" By David Tse and P Viswanath.

5. Another Good Book " Wireless Communication" By A. Goldsmith.

I think after consulting these references it will be very easy to understand MIMO in its real sense.

Cheers!!!!!

MAK

 

[kalaimathi]

Re: MIMO help

@k.sridhar
could you please help me in getting matlab code for 4x4 MIMO using MMSE and the modulation is 16QAM

thank you