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Why is SIMO BER performance is better than MISO?

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bee

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Why is SIMO BER performance is better than MISO?
tx
 

bee said:
Why is SIMO BER performance is better than MISO?
tx
Click to expand...

Because in MISO system the transmitted power is divided among all transmit antennas. Usually space-time codes are used to over come this problem.
 

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    bee

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thanks for your reply. But how does the space-time codes help to over come this issue?
 

bee said:
thanks for your reply. But how does the space-time codes help to over come this issue?
Click to expand...

Actually, I don't have the details, but space-time coding is essentially channel coding and transmit diversity, where the codes are spread in space and in time, i.e.: 2-D code. So, you may expect additional gain from this process.
 

Actually,

Increasing receiving antennas provide diversity gain which benefits in decreasing the BER Curve slope. However, space time codes which needs the use of more than one Transmitting antenna provide shifting BER Curve to left which also, can be considered as a benefit.
 

MISO use multiple transmit antenna, it provides full diversity gain. Example, Space time block codes, with Alamouti scheme - 2 transmit antenna and n receive antenna.
MISO's better than SIMO!
 

What is MISO and SIMO?
MISO: Multiple input and single output, it's mean multiple transmit antennas and single receive antenna.
SIMO: Single input and multiple output, it's mean single transmit antenna and multiple receive antennas.
You know, Space - Time Coding is a type of code to increase the channel capacity or provide the diversity gain, which we want to use, we must have at least 2 transmit antennas.
With 1 transmit antenna we can't use space-time coding for the channel.
So, I really believe that MISO system is better than SIMO system!

Added after 5 hours 42 minutes:

My opinion is only right in case of using Space-time coding! ^^.
 

lequangvu710 said:
What is MISO and SIMO?
MISO: Multiple input and single output, it's mean multiple transmit antennas and single receive antenna.
SIMO: Single input and multiple output, it's mean single transmit antenna and multiple receive antennas.
You know, Space - Time Coding is a type of code to increase the channel capacity or provide the diversity gain, which we want to use, we must have at least 2 transmit antennas.
With 1 transmit antenna we can't use space-time coding for the channel.
So, I really believe that MISO system is better than SIMO system!

Added after 5 hours 42 minutes:

My opinion is only right in case of using Space-time coding! ^^.
Click to expand...

As I know, transmit diversity with space time coding has the same performance as recieve diversity, in terms of diversity gain, i.e.: the slope of BER vs. SNR. Now if you talk about the possibility of increasing the capacity of the channel in transmit diversity, by using spatial multiplexing, this is a different story.

Regards
 

You was right!
But in this case, you should know:
- I just said about SIMO and MISO!
- I introduced about STC.
You didn't understand, so I think you should read what I said clearly!
If we use STC, certainly SIMO can not be used.
 

lequangvu710 said:
You was right!
But in this case, you should know:
- I just said about SIMO and MISO!
- I introduced about STC.
You didn't understand, so I think you should read what I said clearly!
If we use STC, certainly SIMO can not be used.
Click to expand...

Dear lequangvu710,

I didn't misunderstand you, all what I wanted to say is that, STC used in transmit diversity to recover the average SNR loss, compared to a system with recieve diversity. The loss will be 10\,log_{10}L_t, where L_t is the number of transmit antnnas, because the transmitted power is divided among the transmit antennas.

Regards
 

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