Lin eYan
Newbie level 6
exercises of data and signals
Hi, I am a recruit and have some questions while resolving the exercises of Mr. Forouzan's "data communications and networking 4th international edition".
The exercises that I confused are listed below for help.
Added after 32 minutes:
-------- Chapter 3 Data and Signals -------
40. A signal with 200 milliwatts power passes through 10 devices, each with an average noise of 2 microwatts. What is the SNR? What is the SNRdb?
My solution:
a)SNR = the SNR of each devices = 200 milliwatts / 2 microwatts = 200000 microwatts / 2 microwatts = 100000
b)SNRdb = the sum of the SNR of all the 10 devices = 10 * log10(SNR) = 10 log10(200000) = 10 (log10(2) + 5) = 10*5.301 = 53.01 db
Is this correct?
Added after 56 minutes:
48. What is the total delay (latency) for a frame of size 5 million bits that is being sent on a link with 10 routers each having a queuing time of 2µs and a processing time of 1µs. The length of the link is 2000Km. The speed of light inside the link is 2X100,000,000 m/s. The link has a bandwidth of 5Mbps. Which component of the total delay in dominant? Which one is negligible?
a) Queuing time + Processing time = 10*(2µ+1µ)X5000000 = 30s
Should I multiply a frame ( 10(2µ+1µ)*1 ) instead of ( 10(2µ+1µ)*5000000 )?
b) Propagation time = 2000X1000 / 2X100,000,000 = 0.01s
c) Transmission time = 5000,000/5000,000= 1s
Hi, I am a recruit and have some questions while resolving the exercises of Mr. Forouzan's "data communications and networking 4th international edition".
The exercises that I confused are listed below for help.
Added after 32 minutes:
-------- Chapter 3 Data and Signals -------
40. A signal with 200 milliwatts power passes through 10 devices, each with an average noise of 2 microwatts. What is the SNR? What is the SNRdb?
My solution:
a)SNR = the SNR of each devices = 200 milliwatts / 2 microwatts = 200000 microwatts / 2 microwatts = 100000
b)SNRdb = the sum of the SNR of all the 10 devices = 10 * log10(SNR) = 10 log10(200000) = 10 (log10(2) + 5) = 10*5.301 = 53.01 db
Is this correct?
Added after 56 minutes:
48. What is the total delay (latency) for a frame of size 5 million bits that is being sent on a link with 10 routers each having a queuing time of 2µs and a processing time of 1µs. The length of the link is 2000Km. The speed of light inside the link is 2X100,000,000 m/s. The link has a bandwidth of 5Mbps. Which component of the total delay in dominant? Which one is negligible?
a) Queuing time + Processing time = 10*(2µ+1µ)X5000000 = 30s
Should I multiply a frame ( 10(2µ+1µ)*1 ) instead of ( 10(2µ+1µ)*5000000 )?
b) Propagation time = 2000X1000 / 2X100,000,000 = 0.01s
c) Transmission time = 5000,000/5000,000= 1s