## Bit Error Rates of Digital Modulation Techniques

## Bit Error Rates of Digital Modulation Techniques

(OP)

Hi everyone. I am new to this forum and this is my first post. It is an honor to meet all of you.

Currently i am working on a communication system design for a line of sight communication link. I need to find out the

My thoughts are that, to demonstrate the efficiency of the given techniques, I should be using graphs of BER vs Signal-to-Noise ratio and/or BER vs Eb/N0. My trouble is that, i was able to calculate BER using the set values of transmitted power, bandwidth and data rate. However, my supervisor advised that the calculated BER values are wrong and i should refer to the typical graphs of BER vs Eb/N0 in illustrated in books, such as the link stated below.

http://www.keysight.com/upload/cmc_upload/ck/4W/im...

(view the ones in black headings)

Knowing the given concepts, the eb/n0 is found against using a typical value of 10^-7 BER value to demonstrate the effectiveness of a real-life receiver sensitivity threshold. However, given the set parameters, the eb/n0 for the different modulations is set to be lower and these values are perceived to be wrong by my supervisor.

In that case, what are the methods that i could do to demonstrate the effectiveness of my communication systems, and also to show that it meets the requirements of a minimum 10^-7 value with the set values of transmitted power, bandwidth, and data rates?

The given values are as follows:

1) Transmitted Power - 10 Watts

2) Bandwidth - 20 MHz

3) Data rate - 16Mbps

4) Frequency used - 800Hz, 900Hz, 1.24GHz, 1.8GHz, 2GHz, 2.1GHz, 2.4GHz, and 5GHz

Thank you so much everyone who had viewed this post. I greatly appreciate everyone whom is able to give me guidance on this matter. Thank you so much again

Regards,

Jay

Currently i am working on a communication system design for a line of sight communication link. I need to find out the

**bit error rate**of these following techniques:**BPSK, QPSK, 16QAM and 32QAM**.My thoughts are that, to demonstrate the efficiency of the given techniques, I should be using graphs of BER vs Signal-to-Noise ratio and/or BER vs Eb/N0. My trouble is that, i was able to calculate BER using the set values of transmitted power, bandwidth and data rate. However, my supervisor advised that the calculated BER values are wrong and i should refer to the typical graphs of BER vs Eb/N0 in illustrated in books, such as the link stated below.

http://www.keysight.com/upload/cmc_upload/ck/4W/im...

(view the ones in black headings)

Knowing the given concepts, the eb/n0 is found against using a typical value of 10^-7 BER value to demonstrate the effectiveness of a real-life receiver sensitivity threshold. However, given the set parameters, the eb/n0 for the different modulations is set to be lower and these values are perceived to be wrong by my supervisor.

In that case, what are the methods that i could do to demonstrate the effectiveness of my communication systems, and also to show that it meets the requirements of a minimum 10^-7 value with the set values of transmitted power, bandwidth, and data rates?

The given values are as follows:

1) Transmitted Power - 10 Watts

2) Bandwidth - 20 MHz

3) Data rate - 16Mbps

4) Frequency used - 800Hz, 900Hz, 1.24GHz, 1.8GHz, 2GHz, 2.1GHz, 2.4GHz, and 5GHz

Thank you so much everyone who had viewed this post. I greatly appreciate everyone whom is able to give me guidance on this matter. Thank you so much again

Regards,

Jay

## RE: Bit Error Rates of Digital Modulation Techniques

_{0}, nor have you specified anything related to receiver sensitivity, or range. What is your link budget?Beyond that, the analysis is done; there's nothing else to do. Every modulation scheme described is cast in concrete relative to the basic BPSK, and is worse. That relationship cannot change, since the fundamental benefit is higher data rate, which comes at the expense of the energy per bit. Since the higher data rate automatically reduces E

_{b}, which increase BER. You "simply" need to figure realistic values for the noise characteristics.TTFN

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## RE: Bit Error Rates of Digital Modulation Techniques

No. I do not have any sorts of error rate because i'm assuming an ideal system with no internal resistance. The BER vs Eb/N0 graph i'm referring to is as shown below.

http://www.keysight.com/upload/cmc_upload/ck/4W/im...

The link budget is:

GainsTx gain - 20 dB

Rx Gain - 20 dB

LossesLoss - Terrestrial losses. Due to ground bounce, or the Two-ray ground reflection model, and refraction; no multipath, fading, or shadowing. Followed by rain attenuation.

Noise - N = k * T * B; where the k is Boltzmann constant of 1.38 x 10^-23 and T is assuming room temperature, which is 290 Kelvins.

Does that mean that for the analysis, all i have to explain is how the different modulation schemes affect the system's performance isnt't it?

Regards

Jay

## RE: Bit Error Rates of Digital Modulation Techniques

range - 2km, 50km , and 100km

Receiver sensitivity - (-60) dB, minimum threshold which receiver can receiver signal power

Regards

Jay

## RE: Bit Error Rates of Digital Modulation Techniques

_{b}and N_{0}. Given your link budget, one or more of your modulation schemes will meet the BER requirement.TTFN

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## RE: Bit Error Rates of Digital Modulation Techniques

Regards

Jay

## RE: Bit Error Rates of Digital Modulation Techniques

"Knowing the given concepts, the eb/n0 is found against using a typical value of 10^-7 BER value to demonstrate the effectiveness of a real-life receiver sensitivity threshold. However, given the set parameters,

the eb/n0 for the different modulations is set to be lowerand these values are perceived to be wrong by my supervisor. "I had made a mistake for the highlighted section. The Eb/N0 that i had actually calculated is higher than the perceived Eb/N0 of each modulation scheme to meet 10^-7 BER value. Hence, this means that the BER that is obtained from the higher Eb/N0 is lower than the minimally required BER.

In that case, as i had iterated before, what are the methods that i could do to demonstrate the effectiveness of my communication systems, and also to show that it meets the requirements of a minimum 10^-7 value with the set values of transmitted power, bandwidth, and data rates without relying on the obtained lower BER values?

Regards

Jay

## RE: Bit Error Rates of Digital Modulation Techniques

Are you sure that this isn't a homework assignment?

## RE: Bit Error Rates of Digital Modulation Techniques

In that case, as i had iterated before, what are the methods that i could do to demonstrate the effectiveness of my communication systems, and also to show that it meets the requirements of a minimum 10^-7 value with the set values of transmitted power, bandwidth, and data rates without relying on the obtained lower BER values?"

You appear to be confused about the purpose of the analysis. I suspect that your boss thinks your calculations are

OVERLYoptimistic and that you should re-check how you arrived at your E_{b}/N_{0}. It may be that you are correct, but given your apparent lack of experience, and his presumed abundance of experience, the odds are not in your favor. If you have so much margin, then you should be able to do a number of things to reduce the margin, like reducing transmit power, or using a cheaper, noisier receiver, or increasing the data bandwidth. Excess margin equates to excess cost, which is anathema to a tightly run business.As to your question, it's moot. The accepted characterization of a comm system is its BER, so anything else is irrelevant, since there's no other accepted method for comparing systems.

TTFN

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