MIMO for up to 15o km is possible?

[h_rafii]

Hi every body,
I recently involved with MIMO systems in my M.Sc thesis and i have to design a mimo system for very long distances (Up to 150 Km).

I have read some useful papers such as EPM-73 from IEEE for Pathless estimation and other sides of the channel designing.

Ny Quis is that how and with what method i can grantee the orthogonality and polarization in such this far distance???????

Its very interesting to new that what parameters may be against Using MIMO and how to solve them.

 

[vfone]

MIMO was initially developed to increase digital throughput in wireless systems, especially for relative small distances up to about 20km.
I think for a MIMO wireless system would be very hard to work properly at 150km.

Diversity, (which was first proposed before WW2), represent a different method to improve reception at greater distances, initially in HF and later used also in microwaves. This was proven that works fine at very long distances and multipath.

 

[h_rafii]

MIMO was initially developed to increase digital throughput in wireless systems, especially for relative small distances up to about 20km.
I think for a MIMO wireless system would be very hard to work properly at 150km.

Diversity, (which was first proposed before WW2), represent a different method to improve reception at greater distances, initially in HF and later used also in microwaves. This was proven that works fine at very long distances and multipath.

Thanks for your answer dear friend, i also read something about spatial diversity and using two antenna with more than 10 wavelength distance between them like PTP 500 from Motorola.

the Question is that for 150 kilometer Which kind of Diversity is applicable?
i think detecting the signal of tow transmiters antenna at 150 km away would be very hard or impossible.
did you have any idea ???

Dear Vfone,
thanks for your answer, in fact i have been read some papers around diversity, as you can see in PTP-500 MIMO-OFDM system from Motorola, they said for distances upper than 80 km we need to use 2 antenna, such as spatial diversity, but my uestion is that : is it possible to detect tow different signal which are 10-15 meter apart from each other after traveling 150km?

what paper of formula grantee this for such large distance??

 

[vfone]

PTP-500 from Motorola works on 5.8 GHz and I think they use radio relays (Ethernet bridges) to transport data, in relative short distance links connected one to each other.
At this frequency is almost impossible to transmit high data rate over the ground at what they claim, 155 miles (250km) in one shot (line of sight propagation).

First diversity techniques for analog communications were space diversity and frequency diversity. When digital communication appears, were introduced time diversity and multi-user diversity.
For best performance there are wireless systems that use a combination of all of them.

 

[tony_lth]

80KM may not need radio relay, but need high tower, such as 100m or more.
PTP can use spatial diversity, yes, they can capture the TX signals.
Say 5.8GHz, lamda=0.5m, so 5m is enough for antenna separation.

 

[h_rafii]

Dear friend Tony;

did you have any proof for that?

in fact i have read some papers, Motorola said that for long distance (it means uper that 80 km) we need LOS line , and we should use Spatial Diversity for that, 1) Can really MIMO work in LOS Linke for such a distance? 2) Can we use Spatial Diversity ? how in Details?

I'll be thankful if you or any other of frien

 

[tony_lth]

Yes, they must be LOS link.
And spatial diversity is OK.
You can browse and ask more details from PTP vendor, such as Motorola, NEC, etc.
My previous company use 2X2 antennas to implement 600Mb/s, that is simply combining 4 SDH links, each has 155Mb/s as SDH.
I don't know they use same frequency or different frequency, you can ask vnedor.

 

[h_rafii]

thank you for your answers Dear tony;

there is 2 more questions that i have,
1) Spatial diversity for very long distances are applying on OFDM tech or MIMO tech?

2) do you know some paper for do you have some Matlab Progs for Spatial Diversity that could help me?

 

[tony_lth]

I guess PTP spatial diversity uses different frequencies,
Yes, the PTP uses OFDM and MIMO tech,
But I guess what you mean about spatial diversity is for the same frequency.
It's possible if you use different spread spectrum code for the same frequency.

 

[h_rafii]

I guess PTP spatial diversity uses different frequencies,
Yes, the PTP uses OFDM and MIMO tech,
But I guess what you mean about spatial diversity is for the same frequency.
It's possible if you use different spread spectrum code for the same frequency.

Dos it use OFDM and MIMO simultaneously (in very long distances) or it just use OFDM?

 

[tony_lth]

I still think MIMO is possible, i.e. one output, two or four input.