Comments on: Maximal Ratio Combining (MRC)

By: Adem

Adem — Thu, 14 Jan 2010 17:20:16 +0000

Also, if the receiver received two signals from a cooperative path and a direct path, how to combine these two signals using MRC and how to find the overall bit bpsk error probability?
my best regards
Adem

By: Adem

Adem — Thu, 14 Jan 2010 17:08:12 +0000

Hi Krishna,
This is my first time to deal with a Rayleigh fading channel. could you clarify for me the meaning of hi and how to find it using a numerical example?
In a wireless cooperative scheme in which the node that’s in between the receiver and the transmitter recieves the transmitted BPSK signal and amlify it and forward it to the receiver. How to find the overall BPSK bit error probability (in the case of a Rayleigh channel?

By: Krishna Sankar

Krishna Sankar — Sun, 06 Dec 2009 23:48:42 +0000

@Phill: My replies
a) Yes, you may change .* to conv. I use .* as the channel is a single tap (flat fading) hence .* is equivalent to conv.
b) Well, per the model both are complex values (i.e. it affects transmission on sine and cosine transmissions). For you trial, you may try to play with it
c) Well, you might want to make h and awgn from vectors to matrices.

Your english is good.

By: Phill

Phill — Sun, 29 Nov 2009 08:21:37 +0000

Hello Mr. Khrisna, I’m very thankful for ur explanation ’bout this topic…
may I ask ’bout ur code:
y = h.*s + 10^(-Eb_N0_dB(ii)/20)*n;

-Why the rayleigh channel (h) multiplied with signal(s)…can I change the .* with ‘conv’?
-And is AWGN noise and multipath channel always complex value?can I just change them, so it just only hav the real part (without imajiner value)?
-and my last question: what should i do with AWGN & rayleigh ch codes and another codes if I change the data(BPSK) into 2D matrix (e.g. 3×10^6)?

sorry for my terrible english…thanks again…
my rgrds,
Phill

By: Krishna Sankar

Krishna Sankar — Sun, 08 Nov 2009 02:20:28 +0000

@aydar: I agree with your comment. Sorry, I do not have the precise equation for MRC in MIMO case where there is interference.

By: aydar

aydar — Tue, 27 Oct 2009 08:30:44 +0000

Thank you for the reply,

MRC maximizes received SNR after antenna combining. I think, so does ZF in SIMO case too (when ithere is no inter-cell interference), in MIMO it tries to supress interferering MIMO user/stream => maximizes SINR. So, my question is can you write me a formula of MRC for MIMO case or is MRC defined only for SIMO?

Thank you in advance Krishna.

By: Krishna Sankar

Krishna Sankar — Tue, 27 Oct 2009 00:39:34 +0000

@Talib: I would think so. We have multiple copies of the transmitted symbol and we want to combine them optimally.