Comments on: Equal Gain Combining (EGC)

By: Krishna Sankar

Krishna Sankar — Tue, 30 Mar 2010 00:10:58 +0000

@Sharad: In EGC, we make sure that the phases add constructively. Hence the sum of squares of powers makes sense. Agree?

By: Sharad

Sharad — Sat, 27 Feb 2010 09:54:13 +0000

Krishna,
In the first expression for effective Eb/No, shouldn’t it be the square of the sum of all h’s(power of the combined signal) rather than sum of squares(sum of the powers of individual signals)? With the expression that’s mentioned here, I don’t see how you get to the next expression.

By: Ramy Baly

Ramy Baly — Thu, 07 Jan 2010 20:56:38 +0000

Hello
I was trying to do a simulation for EGC using Monte Carlo simulation (not as shown above).
I followed the same steps, but the BER values still high (order of 10^-1). I don’t know why?
Please, can anybody help?

Thanks

By: Ramy Baly

Ramy Baly — Tue, 05 Jan 2010 15:12:40 +0000

Hello Sir,
I tried to implement the EGC using the Monte Carlo simulation and it didn’t work. Is there any explanation?
when trying to take the BER average for only two iterations I get answers of the order (10^-1) while when trying it only one time, I get very low values of BER which is what I want.

Thanks

By: Communications Engineer

Communications Engineer — Sat, 26 Dec 2009 15:55:48 +0000

Krishna,

Can you tell me if Equal Gain Combining is possible is time domain.

If so, can I implement it this way, that I simply sum up the number of chips that come in a Spreading Factor.

So, if SF = 4 and the received spread signal is,

x = [1 1 1 1 -1 -1 -1 1]

then,

EGC(x)@SF=4 = [4 -2]

Is this the correct approach?

By: Krishna Sankar

Krishna Sankar — Mon, 07 Dec 2009 00:02:58 +0000

@communications_engineer: Well, once you despread at the receiver, are you seeing the same information as was transmitted? Maybe to debug, try without spreading.

By: communications_engineer

communications_engineer — Tue, 01 Dec 2009 15:12:38 +0000

Hello, I am using Equal Gain Combining to extract frequency domain diversity in MC-CDMA, but having problems with it.

At the transmitter, I modulate the binary data and repeat the symbols of each user on a given number of subcarriers, multiply it by a frequency domain spreading code (a row vector) and add the spread data of all users to have a composite signal.

At the receiver, for user 1, I multiply it by the same spreading code, and then use EGC to combine the modulation symbols.

I first want to test this algorithm without channel noise/impairments,
therefore, I think EGC will be
EGC = sum(RepSubcarDeSprdU1,1)
To get the sum of all symbols.

The problem, is the when I demodulate the result, there is a large error.

I must mention that this runs will for BPSK but shows errors for QPSK.

Any suggestions?

Thanks Krishna