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Calculate noise power Pn in watts for bandwidth 10 MHz and noise spectral density N0 = 10^-20W/Hz
|
Pn=N0* B = 10^-20 * 10^7 = 10^-13 W
|
Signal-to-noise ratio
|
https://www.etsi.org
|
https://www.3gpp.org
|
https://in.mathworks.com/discovery/snr.html
|
Yes
|
Pn=N0* B = 10^-20\cdot 10^{7} = 10^-13 \text{W}
|
Calculate required Eb/N0(dB) given data rate R=1Mbps and bandwidth B=1.5MHz with SNR=10dB.
|
Eb/N0= SNR*B/R, Linear SNR = 10, Eb/N0 = 10 * 1.5/1 = 15 linear or 10 * log (15) = 11.76 dB
|
Signal-to-noise ratio
|
https://www.etsi.org
|
https://www.3gpp.org
|
https://in.mathworks.com/discovery/snr.html
|
Yes
|
Eb/N0= SNR*B/R \; Linear SNR = 10 \; Eb/N0 = 10\cdot 1.5/1 = 15 linear or 10 * \log(15) = 11.76 \text{dB}
|
Calculate SNR if signal power is -80 dBm and noise power is -100 dBm.
|
SNR = P signal - P noise = -80- (- 100) = 20dB
|
Signal-to-noise ratio
|
https://www.etsi.org
|
https://www.3gpp.org
|
https://in.mathworks.com/discovery/snr.html
|
Yes
|
SNR = P signal - P noise = -80- (- 100) = 20dB
|
Calculate SNR margin if measured SNR is 18 dB and minimum required is 14 dB.
|
Margin= measured SNR -minimum requirement = 18 -14 = 4dB
|
SNR
|
https://www.etsi.org
|
https://www.3gpp.org
|
https://in.mathworks.com/discovery/snr.html
|
Yes
|
Margin= measured SNR -minimum requirement = 18 -14 = 4dB
|
Calculate uplink SNR if received power is -70 dBm and noise power is -110 dBm.
|
SNR= Received power- noise power= -70-(-110)=40 dB
|
Uplink
|
https://www.3gpp.org
|
https://www.etsi.org
|
https://in.mathworks.com/discovery/snr.html
|
Yes
|
SNR= Received power- noise power= -70-(-110)=40 \text{dB}
|
Convert SNR of 12 dB to a linear scale.
|
SNR (linear) = 10^(12/10) = 15.85
|
Signal-to-noise ratio
|
https://www.etsi.org
|
https://www.3gpp.org
|
https://in.mathworks.com/discovery/snr.html
|
Yes
|
Signal-to-noise ratio
|
Calculate TCP throughput for satellite with window size 64 KB and RTT 0.5 s.
|
Throughput = Window Size /RTT= (64 * 8 * 10 ^ 3)/0.5 = 1.024 * 10 ^ 6 bps = 1.024 Mbps
|
TCP over satellite
|
https://www.3gpp.org
|
https://tools.ietf.org/html/rfc1323
|
https://in.mathworks.com/discovery/tcp-satellite.html
|
Yes
|
Throughput = Window Size /RTT= (64\cdot 8\cdot 10^{3})/0.5 = 1.024\cdot 10^{6} bps = 1.024 \text{Mbps}
|
Calculate TCP throughput if window size is 1 MB and RTT is 600 ms.
|
Throughput = Window Size*8 /RTT = (1 * 10 ^ 6 * 8)/0.6 = 13.33 * 10 ^ 6 bps = 13.33 Mbps
|
TCP over satellite
|
https://www.3gpp.org
|
https://tools.ietf.org/html/rfc1323
|
https://in.mathworks.com/discovery/tcp-satellite.html
|
Yes
|
Throughput = Window Size*8 /RTT = (1\cdot 10^{6} * 8)/0.6 = 13.33\cdot 10^{6} bps = 13.33 \text{Mbps}
|
Calculate TCP throughput if window size is 100 KB and RTT 450 ms.
|
Throughput = (100 * 8 * 10 ^ 3)/0.45 = 1.778 * 10 ^ 6 * bps = 1.778 Mbps
|
TCP over satellite
|
https://www.3gpp.org
|
https://tools.ietf.org/html/rfc1323
|
https://in.mathworks.com/discovery/tcp-satellite.html
|
Yes
|
Throughput = (100\cdot 8\cdot 10^{3})/0.45 = 1.778\cdot 10^{6} * bps = 1.778 \text{Mbps}
|
Calculate TCP window size needed for 5 Mbps throughput with RTT 0.4 s.
|
Window size = Throughput × RTT = 5 * 10 ^ 6 * 0.4 = 2 * 10 ^ 6 bits= 250 KB
|
TCP over satellite
|
https://www.3gpp.org
|
https://tools.ietf.org/html/rfc1323
|
https://in.mathworks.com/discovery/tcp-satellite.html
|
Yes
|
Window size = Throughput \times RTT = 5\cdot 10^{6} * 0.4 = 2\cdot 10^{6} bits= 250 KB
|
Estimate TCP throughput if packet loss rate is 0.01 and RTT 0.6 s.
|
Throughput = MSS/ (RTT*√p). Assuming MSS=1500 bytes:(1500*8)/ (0.6*√0.01)= 12000/(0.6 * 0.1) = 200000 bps = 200 Kbps
|
TCP over satellite
|
https://www.etsi.org
|
https://tools.ietf.org/html/rfc1323
|
https://in.mathworks.com/discovery/tcp-satellite.html
|
Yes
|
TCP over satellite
|
For given bandwidth 20 MHz and spectral efficiency 4 bps/Hz, find downlink peak data rate.
|
R = B × η = 20 × 10^6 x 4 = 80 × 10^6 bps = 80 Mbps
|
Downlink
|
https://www.3gpp.org
|
https://www.etsi.org
|
https://in.mathworks.com/discovery/throughput.html
|
Yes
|
Downlink
|
Calculate round trip time for TT&C if distance to GEO satellite is 36,000 km.
|
RTT = 2 * distance/ speed of light= (2*36,000*10^3)/3*10^8 = 0.24 s = 240 ms
|
TT&C
|
https://www.3gpp.org
|
https://www.etsi.org
|
https://in.mathworks.com/discovery/ttc.html
|
Yes
|
RTT = 2 * distance/ speed of light= (2\cdot 36 \; 000\cdot 10^{3})/3\cdot 10^{8} = 0.24 \text{s} = 240 ms
|
How does rain attenuation differ at various frequency bands in a link budget?
|
Rain attenuation increases with frequency. High-frequency bands like Ku, Ka, and V are more affected by rain, causing greater signal loss, while lower frequencies such as L and S bands experience minimal rain impact. In a link budget, expected rain attenuation must be included to maintain a positive link margin and ensure reliable communication during rainy conditions.
|
Link Budget
|
https://doi.org/10.1155/2020/6669969
|
https://doi.org/10.54254/2755-2721/12/20230355
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
No
| null |
A link has SNR = 20 dB. If noise power = -100 dBm, what is the received signal power?
|
Signal power = -100 + 20 = -80 dBm.
|
Link Budget
|
https://doi.org/10.1155/2020/6669965
|
http://www.scitechpub.org/wp-content/uploads/2020/09/SCITECHP420103.pdf
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
Yes
|
Ps(dBm)=Pn(dBm)+SNR(dB)
|
A satellite has 20 dBW EIRP, free-space path loss 155 dB, receive antenna gain 25 dBi, receiver loss 2 dB. receiver sensitivity is -120 dBW, compute link margin.
|
LM=Pr−Pmin=−112−(−120) =8 dB. Positive margin ensures buffer against fading or additional losses.
|
Link Budget
|
https://doi.org/10.1155/2020/6669969
|
https://doi.org/10.54254/2755-2721/12/20230355
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
Yes
|
L_M=P_r−P_{min}=−112−(−120) =8 dB
|
A satellite link requires 20 dB C/N. Received power is -105 dBW. What is the maximum allowable noise power?
|
C/N = Pr - N → N = Pr - C/N = -105 -20 = -125 dBW. Noise power must not exceed -125 dBW to maintain reliable link.
|
Link Budget
|
https://doi.org/10.1155/2020/6669969
|
https://doi.org/10.54254/2755-2721/12/20230355
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
Yes
|
C/N = P_r - N \rightarrow N = P_r - C/N = -105 -20 = -125 dBW
|
A transmitter sends 10 W, antenna gain is 5 dB, and path loss is 10 dB. What is the received power in dB?
|
Convert 10 W to dBW: 10log (10) =10) dBW. Received power (Pr = 10 + 5 - 10 = 5) dBW. So the receiver gets 5 dBW. Simple addition/subtraction of gain and loss gives the received power.
|
Link Budget
|
https://doi.org/10.1155/2020/6669965
|
http://www.scitechpub.org/wp-content/uploads/2020/09/SCITECHP420103.pdf
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
yes
|
P_t(\text{dBW}) = 10 \cdot \log_{10}(P_t) P_r = 10 + 5 - 10 = 5\,\text{dBW}
|
How do fade margins help in maintaining a reliable satellite link?
|
Fade margin represents the additional power included in the link budget to compensate for unpredictable losses such as rain, atmospheric absorption, or antenna misalignment.
It is calculated as the difference between the actual received power and the minimum required power for reliable communication:
Mf=Pr−Pmin
where
Mf is the fade margin (dB),
Pr is the received power (dB), and
Pmin is the minimum power required by the receiver for proper demodulation (dB).
For example, if Pr=−100 dBW
Pmin=−105 dBW=−105dBW, the fade margin is
Mf=5 dB Including this margin ensures the link remains operational during temporary degradations, thereby enhancing link reliability.
|
Link Budget
|
https://doi.org/10.1155/2020/6669969
|
https://doi.org/10.54254/2755-2721/12/20230355
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
Yes
|
M_f = P_r - P_{\text{min}}
|
How do pointing losses affect a high-gain satellite antenna?
|
If a high-gain antenna is misaligned, its effective gain decreases due to pointing loss.
In the link budget, this is represented as a reduction in antenna gain:
Geff=Gt−Lp
where
Geff is the effective antenna gain (dB),
Gt is the nominal transmit antenna gain (dB), and
Lp is the pointing loss (dB).
For example, if Gt=45 dB =45dB and Lp=2 dB, then Geff=43 dB =43dB.
High-gain, narrow-beam antennas are particularly sensitive to such misalignment, so engineers include
Lp in the link budget and design precise control systems to minimize pointing errors.
|
Link Budget
|
https://doi.org/10.1155/2020/6669969
|
https://doi.org/10.54254/2755-2721/12/20230355
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
Yes
|
G_{\text{eff}} = G_t - L_p
|
How do you calculate Effective Isotropic Radiated Power (EIRP)?
|
The Effective Isotropic Radiated Power (EIRP) is a measure of how much power a transmitting antenna radiates in its most focused direction. It combines the effects of the transmitter’s power and antenna gain, while subtracting losses. It is given by EIRP=Pt+Gt−Lt where Pt is transmit power, Gt is antenna gain, and Lt represents system losses. EIRP allows engineers to compare different transmission systems and ensure the transmitted signal is strong enough to be received at a given distance with minimal distortion or loss.
|
Link Budget
|
https://doi.org/10.1155/2020/6669965
|
http://www.scitechpub.org/wp-content/uploads/2020/09/SCITECHP420103.pdf
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
yes
|
EIRP=Pt+Gt−Lt
|
How does halving the distance between satellite and ground affect free-space path loss?
|
Halving the distance between the satellite and the ground reduces the free-space path loss (FSL). The FSL is given by the formula:
\[
\text{FSL} = 20 \log_{10} (d)
\]
where \( d \) is the distance between the satellite and the receiver. When the distance is halved, \( d' = \frac{d}{2} \), the change in FSL is:
\[
\Delta \text{FSL} = 20 \log_{10} \left( \frac{d}{2} \right) = 20 \log_{10} (d) - 20 \log_{10} (2)
\]
Thus, the reduction in FSL is approximately:
\[
\Delta \text{FSL} = - 20 \log_{10} (2) \approx -6 \, \text{dB}
\]
This means the received power increases by 6 dB when the distance is halved. Engineers can take advantage of shorter distances or lower orbits to improve signal strength.
|
Link Budget
|
https://doi.org/10.1155/2020/6669969
|
https://doi.org/10.54254/2755-2721/12/20230355
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
Yes
|
\[\text{FSL} = 20 \log_{10} (d)\] \[\Delta \text{FSL} = 20 log_{10} \left( \frac{d}{2} \right) = 20 \log_{10} (d) - 20 \log_{10} (2)\] \[\Delta \text{FSL} = 20 \log_{10} \left( \frac{d}{2} \right) = 20 \log_{10} (d) - 20 \log_{10} (2)\]
|
How is received power estimated in link budget analysis?
|
Received power (Pr) is the total signal power at the receiving antenna after accounting for all gains and losses in the system. It is calculated using the equation Pr=Pt+Gt+Gr−Lp, where Pt is the transmitted power, Gt and Gr are the transmitter and receiver antenna gains, and Lp is the path loss in dB. This simple relationship helps determine whether the signal level at the receiver is strong enough for correct detection. In practical terms, higher antenna gains or transmit power improve received signal levels.
|
Link Budget
|
https://doi.org/10.1155/2020/6669965
|
http://www.scitechpub.org/wp-content/uploads/2020/09/SCITECHP420103.pdf
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
yes
|
Pr=Pt+Gt+Gr−Lp
|
If a 15 W transmitter communicates through a lossy cable of 1.5 dB, how is EIRP affected?
|
Cable loss reduces the effective power reaching the antenna. P effective=Pt−L cable=15 W≈11.76W → 10.7 dBW. If antenna gain is 20 dBi, EIRP = 10.7 + 20 = 30.7 dBW. Including cable losses ensures the link budget accurately reflects real transmitted power, preventing overestimation of received power and link margin.
|
Link Budget
|
https://doi.org/10.1155/2020/6669969
|
https://doi.org/10.54254/2755-2721/12/20230355
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
Yes
|
Cable loss reduces the effective power reaching the antenna. P effective=Pt-L cable=15 \text{W}≈11.76W → 10.7 \text{dBW}. If antenna gain is 20 dBi \; EIRP = 10.7 + 20 = 30.7 \text{dBW}. Including cable losses ensures the link budget accurately reflects real transmitted power
|
If rain attenuation is 3 dB, how should the link budget be adjusted?
|
Rain attenuation adds extra loss to the link. In the budget, this 3 dB is added to total path loss, reducing received power. Engineers may compensate by increasing EIRP, using higher-gain antennas, or adding fade margin. For example, if FSL is 150 dB, EIRP 30 dBW, and receive antenna gain 20 dBi, the new Pr=30+20−(150+3) =−103 dBW. Proper adjustment ensures signal stays above minimum required power.
|
Link Budget
|
https://doi.org/10.1155/2020/6669969
|
https://doi.org/10.54254/2755-2721/12/20230355
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
Yes
|
the new Pr=30+20-(150+3) =-103 \text{dBW}. Proper adjustment ensures signal stays above minimum required power.
|
If rain increases path loss by 3 dB, by how much should antenna gain be increased to maintain the same received power?
|
To compensate for 3 dB additional loss, the antenna gain should be increased by 3 dB. For example, if original Gr = 20 dBi, new Gr = 23 dBi. This keeps received power unchanged, maintaining link reliability without increasing transmitter power.
|
Link Budget
|
https://doi.org/10.1155/2020/6669969
|
https://doi.org/10.54254/2755-2721/12/20230355
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
Yes
|
if original Gr = 20 dBi \; new Gr = 23 dBi. This keeps received power unchanged
|
Received power = -100 dBW, minimum required = -110 dBW. Find link margin.
|
Link Margin LM=Pr−Pmin=−100−(−110) =10 dB. Positive margin shows signal is strong enough.
|
Link Budget
|
https://doi.org/10.1155/2020/6669965
|
http://www.scitechpub.org/wp-content/uploads/2020/09/SCITECHP420103.pdf
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
yes
|
Link Margin LM=Pr-Pmin=-100-(-110) =10 \text{dB}. Positive margin shows signal is strong enough.
|
Transmit power = 5 W, transmitter gain = 3 dB, receiver gain = 2 dB, path loss = 8 dB. Find received power.
|
Convert 5 W: 10log10(5) = 6.99 ≈ 7dBW. Then (Pr = 7 + 3 + 2 - 8 = 4dBW. Received power is 4 dBW. Simple arithmetic gives an easy link budget result.
|
Link Budget
|
https://doi.org/10.1155/2020/6669965
|
http://www.scitechpub.org/wp-content/uploads/2020/09/SCITECHP420103.pdf
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
yes
|
Convert 5 \text{W}: 10log10(5) = 6.99 ≈ 7dBW. Then (Pr = 7 + 3 + 2 - 8 = 4dBW. Received power is 4 \text{dBW}. Simple arithmetic gives an easy link budget result.
|
Transmitter power = 20 W, antenna gain = 4 dB, path loss = 14 dB. Find received power.
|
Convert 20 W: 10log10(20) = 13 dBW. Then Pr = 13 + 4 - 14 = 3 dBW. Receiver gets 3 dBW. Very simple addition/subtraction problem.
|
Link Budget
|
https://doi.org/10.1155/2020/6669965
|
http://www.scitechpub.org/wp-content/uploads/2020/09/SCITECHP420103.pdf
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
yes
|
Convert 20 \text{W}: 10log10(20) = 13 \text{dBW}. Then Pr = 13 + 4 - 14 = 3 \text{dBW}. Receiver gets 3 \text{dBW}. Very simple addition/subtraction problem.
|
Using Pr=−108.45 dBW (Q13) and N=−126.05 dBW (Q14), compute C/N in dB.
|
C/N=Pr−N=−108.45−(−126.05) =17.60 dB (rounded). This means the carrier is ~17.6 dB above the noise floor — a healthy margin for many modulations. Link designers use C/N to predict bit error rates and choose modulation/coding. If C/N is too low, increase EIRP, antenna gain, or reduce bandwidth/noise to improve the link.
|
Link Budget
|
https://doi.org/10.1155/2020/6669965
|
http://www.scitechpub.org/wp-content/uploads/2020/09/SCITECHP420103.pdf
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
yes
|
C/\text{N}=Pr-\text{N}=-108.45-(-126.05) =17.60 \text{dB} (rounded). This means the carrier is ~17.6 \text{dB} above the noise floor — a healthy margin for many modulations. Link designers use C/\text{N} to predict bit error rates and choose modulation/coding. If C/\text{N} is too low
|
What does free-space path loss represent in link budget analysis?
|
Free-space path loss (FSL) represents the weakening of a radio signal as it travels through space without obstacles. It increases with both distance and frequency. The FSL can be calculated using FSL=20log10(d)+20log10(f)+92.44 where d is distance in kilometres and f is frequency in gigahertz. This loss occurs naturally due to the spreading of the wavefront over distance. Understanding FSL helps engineers predict how much power is lost before the signal reaches the receiver, which is essential for maintaining reliable satellite and wireless communications.
|
Link Budget
|
https://doi.org/10.1155/2020/6669965
|
http://www.scitechpub.org/wp-content/uploads/2020/09/SCITECHP420103.pdf
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
Yes
|
FSL=20log10(d)+20log10(f)+92.44
|
What is link margin in link budget analysis?
|
Link margin indicates the safety buffer or extra signal strength available above the minimum required level for proper reception. It is calculated using LM=Pr
|
Link Budget
|
https://doi.org/10.1155/2020/6669965
|
http://www.scitechpub.org/wp-content/uploads/2020/09/SCITECHP420103.pdf
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
yes
|
Link margin indicates the safety buffer or extra signal strength available above the minimum required level for proper reception. It is calculated using LM=Pr
|
What is the importance of noise power in link budget analysis?
|
Noise power defines the amount of unwanted signal present in the receiver that can interfere with communication. It is an essential factor for determining the quality of the received signal. Noise power is given by N=kTB where k is Boltzmann’s constant, T is system temperature, and B is bandwidth. In link budget analysis, noise power helps calculate the signal-to-noise ratio (SNR), which directly affects system performance. Lower noise levels or narrower bandwidths help improve signal clarity and ensure better data accuracy in communication links.
|
Link Budget
|
https://doi.org/10.1155/2020/6669965
|
http://www.scitechpub.org/wp-content/uploads/2020/09/SCITECHP420103.pdf
|
https://iopscience.iop.org/article/10.1088/1742-6596/1152/1/012021/pdf
|
Yes
|
N=kTB
|
How do atmospheric conditions influence downlink performance?
|
Atmospheric conditions like rain, clouds, and ionospheric disturbances can cause signal attenuation and scattering, leading to increased BER and potential data loss. Engineers account for these factors in system design and planning.
|
Downlink
|
https://www.researchgate.net/publication/228654284_Design_and_Performance_Analysis_of_Downlink_in_Space_Communications_System_for_Lunar_Exploration
|
https://www.sciencedirect.com/science/article/abs/pii/S0045790622002737
|
https://jwcn-eurasipjournals.springeropen.com/articles/10.1186/s13638-018-1104-7
|
No
| null |
How does distance affect downlink performance?
|
Longer distances between a satellite and ground station cause signal weakening due to free-space path loss. For lunar missions, the enormous distance means the transmitted signal must be strong enough to overcome this loss. Engineers compensate with higher transmit power, large antennas, and precise alignment. The longer the distance, the greater the chance of errors and delays, so careful planning is needed to maintain a reliable downlink that ensures accurate delivery of scientific and telemetry data.
|
Downlink
|
https://www.researchgate.net/publication/228654284_Design_and_Performance_Analysis_of_Downlink_in_Space_Communications_System_for_Lunar_Exploration
|
https://www.sciencedirect.com/science/article/abs/pii/S0045790622002737
|
https://jwcn-eurasipjournals.springeropen.com/articles/10.1186/s13638-018-1104-7
|
No
| null |
How is link budget analysis used in designing a downlink?
|
Link budget analysis calculates the total gains and losses in the communication path. It considers transmit power, antenna gains, path loss, and noise to ensure the received signal meets the required quality. By analyzing the link budget, engineers can select transmitter power, antenna size, and modulation schemes to maintain a reliable downlink with acceptable error rates.
|
Downlink
|
https://www.researchgate.net/publication/228654284_Design_and_Performance_Analysis_of_Downlink_in_Space_Communications_System_for_Lunar_Exploration
|
https://www.sciencedirect.com/science/article/abs/pii/S0045790622002737
|
https://jwcn-eurasipjournals.springeropen.com/articles/10.1186/s13638-018-1104-7
|
No
| null |
What challenges are associated with downlinking from the Moon?
|
Challenges include the very long distance, leading to signal weakening; alignment issues between spacecraft and ground stations; and interference from Earth’s atmosphere. These factors can cause low signal-to-noise ratio or data errors. Engineers overcome these challenges with high-gain antennas, error correction, careful frequency selection, and optimal transmission scheduling.
|
Downlink
|
https://www.researchgate.net/publication/228654284_Design_and_Performance_Analysis_of_Downlink_in_Space_Communications_System_for_Lunar_Exploration
|
https://www.sciencedirect.com/science/article/abs/pii/S0045790622002737
|
https://jwcn-eurasipjournals.springeropen.com/articles/10.1186/s13638-018-1104-7
|
No
| null |
What is a downlink in space communication?
|
A downlink refers to the transmission of data from a spacecraft, such as a lunar orbiter, to a ground station on Earth. This process allows scientists and engineers to receive telemetry, images, and other data collected by the spacecraft during its mission.
|
Downlink
|
https://www.researchgate.net/publication/228654284_Design_and_Performance_Analysis_of_Downlink_in_Space_Communications_System_for_Lunar_Exploration
|
https://www.sciencedirect.com/science/article/abs/pii/S0045790622002737
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https://jwcn-eurasipjournals.springeropen.com/articles/10.1186/s13638-018-1104-7
|
No
| null |
What is the role of antennas in downlink communication?
|
Antennas are crucial for transmitting and receiving signals in downlink communication. A spacecraft’s antenna focuses the signal toward Earth, while the ground station’s antenna collects the weak signal from space. The design, size, and gain of the antenna determine the strength and quality of the downlink. High-gain antennas reduce signal spreading, improving reliability and ensuring the data, such as images or telemetry, is received accurately, even over large distances like those between the Moon and Earth.
|
Downlink
|
https://www.researchgate.net/publication/228654284_Design_and_Performance_Analysis_of_Downlink_in_Space_Communications_System_for_Lunar_Exploration
|
https://www.sciencedirect.com/science/article/abs/pii/S0045790622002737
|
https://jwcn-eurasipjournals.springeropen.com/articles/10.1186/s13638-018-1104-7
|
No
| null |
What is the significance of a target bit error rate (BER) in downlink systems?
|
A target BER, such as 10⁻⁵, defines the acceptable level of data errors in the received signal. Achieving this target ensures that the transmitted data is accurately received, maintaining the integrity of scientific information.
|
Downlink
|
https://www.researchgate.net/publication/228654284_Design_and_Performance_Analysis_of_Downlink_in_Space_Communications_System_for_Lunar_Exploration
|
https://www.sciencedirect.com/science/article/abs/pii/S0045790622002737
|
https://jwcn-eurasipjournals.springeropen.com/articles/10.1186/s13638-018-1104-7
|
No
| null |
Why is downlink reliability important for lunar missions?
|
Downlink reliability ensures that critical data collected by the spacecraft, like images, scientific measurements, and telemetry, is received correctly on Earth. A weak or unstable downlink can result in lost information or errors. Engineers must consider long distances, atmospheric effects, and alignment to maintain strong signal quality. Reliable downlink allows continuous monitoring and successful completion of mission objectives.
|
Downlink
|
https://www.researchgate.net/publication/228654284_Design_and_Performance_Analysis_of_Downlink_in_Space_Communications_System_for_Lunar_Exploration
|
https://www.sciencedirect.com/science/article/abs/pii/S0045790622002737
|
https://jwcn-eurasipjournals.springeropen.com/articles/10.1186/s13638-018-1104-7
|
No
| null |
A downlink has bandwidth 5 MHz and SNR = 15 (linear). What is the theoretical maximum data rate?
|
Using Shannon: C = B log₂(1 + SNR) = 5×10⁶ × log₂(1 + 15) ≈ 5×10⁶ × 4 = 20 Mbps. This shows the maximum data the link can carry under these conditions.
|
Downlink
|
https://www.researchgate.net/publication/228654284_Design_and_Performance_Analysis_of_Downlink_in_Space_Communications_System_for_Lunar_Exploration
|
https://www.sciencedirect.com/science/article/abs/pii/S0045790622002737
|
https://jwcn-eurasipjournals.springeropen.com/articles/10.1186/s13638-018-1104-7
|
Yes
|
C = B × log₂(1 + SNR)
|
A satellite downlink uses 10 W transmitted power. The path loss is 120 dB. What is the received power in watts?
|
Received power Pr = Pt ÷ 10^(PL/10) = 10 ÷ 10^(120/10) = 10 ÷ 10¹² = 1 × 10⁻¹² W. Shows how distance drastically reduces signal strength.
|
Downlink
|
https://www.researchgate.net/publication/228654284_Design_and_Performance_Analysis_of_Downlink_in_Space_Communications_System_for_Lunar_Exploration
|
https://www.sciencedirect.com/science/article/abs/pii/S0045790622002737
|
https://jwcn-eurasipjournals.springeropen.com/articles/10.1186/s13638-018-1104-7
|
Yes
|
Received power P_r = P_t / 10^(P_L/10) = 10 / 10^(120/10) = 10 / 10^{12} = 1 \times 10^{-12} W
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What are the sources of noise in a communication system, and how does it affect the receiver's performance?
|
Noise comprises all unwanted contributions that increase the overall power alongside the desired carrier power. It diminishes the receiver's ability to accurately reproduce the information contained in the desired carrier. The sources of noise include the radiation emitted by natural sources within the antenna's reception area and the noise generated by components within the receiving equipment. Signals from transmitters that are not intended for reception are also categorized as noise, referred to as interference.
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Link budget
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https://link.springer.com/chapter/10.1007/978-3-031-76455-4_3
|
https://www.sciencedirect.com/science/article/pii/S2949736125000491
|
https://link.springer.com/article/10.1007/s00359-021-01516-z
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No
| null |
What measures can be taken to address the difference in power budget calculations between uplink and downlink?
|
The uplink and downlink power budget calculations show a significant difference, with downlink path loss exceeding uplink power loss. This indicates that the coverage area of the base station antenna is greater than that of the mobile station antenna, providing more coverage in the downlink direction. While reducing downlink power can decrease this difference, it also leads to a loss of coverage; alternatively, introducing diversity or low-noise amplifiers (LNA) at the base transceiver station (BTS) can enhance the receiver power level.
|
Link budget
|
https://jwcn-eurasipjournals.springeropen.com/articles/10.1186/s13638-022-02133-3
|
https://www.sciencedirect.com/science/article/abs/pii/S1389128622001906
|
https://link.springer.com/article/10.1007/s11235-020-00661-1
|
No
| null |
How does onboard processing help in disaster monitoring and emergency response?
|
Onboard processing allows satellites to analyze data in real-time and transmit only the critical information to ground stations. For example, in case of a flood or wildfire, satellites can detect affected areas and send alerts immediately. This reduces the time needed to process raw data on Earth and enables faster decision-making by authorities. By prioritizing urgent data, onboard processing supports timely disaster response, efficient resource allocation, and improved safety for affected populations. It enhances the usefulness of satellite systems in emergency situations.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
No
| null |
How does onboard processing help in Earth observation missions?
|
Earth observation satellites collect massive amounts of data, like images or sensor readings. Onboard processing allows the satellite to analyze, compress, or filter this data before sending it to Earth. For example, clouds or irrelevant pixels can be removed, reducing transmission load. This enables faster delivery of meaningful data for weather monitoring, agriculture, or disaster response. It also supports autonomous operations, where satellites can detect critical events in near real-time and send only essential information, improving mission efficiency and responsiveness.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
No
| null |
How does onboard processing improve satellite communication efficiency?
|
Onboard processing allows satellites to manage signals directly in space. They can filter, compress, or route data before sending it to ground stations. This reduces bandwidth usage and communication delays. It ensures that only important or relevant data is transmitted, optimizing satellite resources. Additionally, it reduces workload on ground stations and allows faster data delivery to end users, which is critical for time-sensitive applications like video conferencing, real-time monitoring, and internet services. Overall, it makes satellite communication more efficient and reliable.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
No
| null |
How does onboard processing support autonomous satellite operations?
|
Onboard processing enables satellites to make decisions without waiting for ground control. For example, satellites can detect anomalies, switch communication paths, or prioritize critical data. This autonomy is important for remote or deep-space missions, where communication delays make real-time ground control difficult. Autonomous onboard processing allows faster responses, reduces dependence on Earth stations, and improves mission efficiency. It also enhances reliability and ensures continuous operation even if ground communication is temporarily unavailable.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
No
| null |
What are the advantages of onboard processing over traditional satellites?
|
Advantages include reduced bandwidth usage, lower communication costs, faster data delivery, and autonomous operation. Satellites can filter, compress, and process data onboard, sending only useful information to Earth. This is especially important for high-data missions like imaging or remote sensing. Onboard processing also reduces ground system workload, improves real-time responsiveness, and allows satellites to operate independently for longer durations. Overall, it enhances mission efficiency, supports advanced applications, and improves network resource utilization compared to traditional satellites that only relay raw data.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
No
| null |
What are the challenges of onboard processing in satellites?
|
Key challenges include limited power, weight, and space for onboard processors. Satellites must use radiation-hardened components to withstand space conditions. Processing large volumes of data requires efficient algorithms and low-energy designs. Heat dissipation, fault tolerance, and reliability are also critical. Despite these challenges, onboard processing is essential for high-data missions and advanced communication applications. Engineers must balance performance, power consumption, and system reliability when designing onboard processing systems.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
No
| null |
What are the main tasks performed in onboard processing?
|
The main tasks include data filtering, compression, routing, storage, and preliminary analysis. Satellites may also perform signal processing, such as modulation/demodulation or error correction. These tasks reduce the amount of data sent to Earth, improve communication efficiency, and support autonomous operations. Onboard processing is crucial in communication satellites, Earth observation satellites, and scientific missions to handle large volumes of data. It ensures faster delivery of useful information and optimizes satellite resources while reducing ground system workload.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
No
| null |
What are the types of processing commonly done onboard satellites?
|
Common onboard processing includes data compression, signal modulation/demodulation, error correction, routing, filtering, and preliminary analysis of sensor data. In communication satellites, it can also include beamforming or routing traffic to multiple ground stations. In Earth observation satellites, processing might include image correction, cloud removal, or anomaly detection. These tasks reduce transmitted data, improve signal quality, and enable autonomous operation. Onboard processing ensures that only useful and relevant information reaches Earth, optimizing satellite and network performance.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
No
| null |
What is onboard processing in satellites?
|
Onboard processing refers to the satellite’s ability to process data directly in space rather than sending raw data to Earth. It includes tasks like filtering, compressing, analyzing, and storing data. This reduces the amount of data transmitted, saves bandwidth, and allows faster decision-making. Onboard processing is important for real-time applications such as Earth observation, weather monitoring, and communication networks. It also enables autonomous satellite operation and efficient use of satellite resources. By processing data in orbit, satellites can respond quickly to changing conditions and reduce reliance on ground stations.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
No
| null |
What is the role of onboard processing in communication satellites?
|
In communication satellites, onboard processing manages signals directly in space. It can perform tasks like routing, signal amplification, modulation, and error correction. This reduces the data load sent to ground stations and allows multiple users to share bandwidth efficiently. Onboard processing helps improve signal quality, reduce latency, and optimize resource allocation. It also enables flexible network management, such as dynamically connecting users or adjusting bandwidth allocation in real-time. Overall, it makes satellite communication more reliable and efficient compared to satellites that only act as passive relays.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
No
| null |
Why is onboard processing important for deep-space missions?
|
In deep-space missions, communication delays with Earth can be significant. Onboard processing enables satellites or spacecraft to analyze data, make decisions, and operate autonomously without waiting for ground commands. For example, a spacecraft can detect anomalies, prioritize critical data, or adjust its path using onboard algorithms. This reduces dependence on ground control and allows faster responses to unexpected events. It is essential for mission success, safety, and efficiency in distant or remote operations where real-time communication is impossible.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
No
| null |
Why is onboard processing important?
|
Onboard processing is important because it increases efficiency and reduces communication delays. Satellites can analyze data before sending it to Earth, which saves bandwidth and lowers transmission costs. It is especially useful in high-data applications, like imaging satellites or scientific instruments. By processing onboard, satellites can provide near-real-time data for decision-making. It also enables autonomous control, faster responses to critical events, and better management of network resources. Overall, onboard processing improves mission performance and allows satellites to support more advanced services without overloading ground systems.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
No
| null |
A satellite receives 100 Mbps of raw data and compresses it onboard by 40%. Find the data rate sent to Earth.
|
Compressed data rate = 100 × (1 − 0.4) = 60 Mbps. Onboard processing reduces the data volume before transmission, saving bandwidth and reducing communication costs. This ensures faster delivery and better use of satellite resources for communication or observation.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
Yes
|
Compressed data rate = 100 \times (1 − 0.4) = 60 Mbps
|
A satellite receives signals at 100 W and processes them with 90% efficiency. Find effective power after processing.
|
Effective power = 100 × 0.9 = 90 W. Onboard processing improves signal quality but may have slight losses; knowing efficiency helps design power budgets and ensure reliable transmission.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
Yes
|
Effective power = 100 \times 0.9 = 90 W
|
A satellite transmits 50 Mbps through a channel with SNR = 10 (linear). Calculate the Shannon capacity.
|
C = B × log₂(1 + SNR). Assume B = 50 MHz → C = 50 × log₂(11) ≈ 50 × 3.46 ≈ 173 Mbps. This shows the maximum theoretical data rate, and onboard processing helps approach this capacity by optimizing signal quality.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
Yes
|
C = B \times log_2(1 + SNR)
|
A satellite uses 200 W power for onboard processing. If the satellite’s total power is 800 W, find the percentage of power used for processing.
|
Power % = (200 ÷ 800) × 100 = 25%. Understanding power allocation is crucial since onboard processing consumes energy, and satellites must balance processing with other subsystems like communication and sensors.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
Yes
|
Power % = (200 / 800) \times 100 = 25\%
|
An imaging satellite collects 500 GB/day. If onboard processing removes 30% redundant data, how much data is transmitted to Earth daily?
|
Data sent = 500 × (1 − 0.3) = 350 GB/day. Onboard filtering and processing help minimize unnecessary transmissions, making efficient use of limited satellite bandwidth and reducing the load on ground stations.
|
Onboard processing
|
https://www.sciencedirect.com/science/article/pii/S0167926021000559
|
https://ieeexplore.ieee.org/abstract/document/10834581/
|
https://link.springer.com/article/10.1007/s42405-025-00885-y
|
Yes
|
Data sent = 500 \times (1 − 0.3) = 350 GB/day
|
What happens when TCP over Satellite faces rain fade?
|
Rain fade weakens the signal, causing temporary packet loss or disconnections. TCP over Satellite responds by slowing down, but error correction and power control can keep data flowing.
|
TCP over satellite
|
https://www.cell.com/heliyon/fulltext/S2405-8440(24)09824-4
|
https://www.mdpi.com/2673-8732/4/3/12
|
https://netdevconf.info/0x15/papers/32/paper-final.pdf
|
No
| null |
What is slow start in TCP over Satellite?
|
TCP over Satellite starts transmission slowly with a small congestion window, then gradually increases it to avoid overload. This process helps the network adjust to delay conditions.
|
TCP over satellite
|
https://www.cell.com/heliyon/fulltext/S2405-8440(24)09824-4
|
https://www.mdpi.com/2673-8732/4/3/12
|
https://netdevconf.info/0x15/papers/32/paper-final.pdf
|
No
| null |
What is TCP over Satellite?
|
TCP over Satellite means using the Transmission Control Protocol (TCP) for communication through satellites. It provides reliable data transfer even when signals travel long distances and experience high delay.
|
TCP over satellite
|
https://www.cell.com/heliyon/fulltext/S2405-8440(24)09824-4
|
https://www.mdpi.com/2673-8732/4/3/12
|
https://netdevconf.info/0x15/papers/32/paper-final.pdf
|
No
| null |
What is the impact of high latency on web browsing using TCP over Satellite?
|
High latency makes each TCP handshake and page request slower. TCP over Satellite users often notice pages loading in stages because each object waits for long acknowledgments.
|
TCP over satellite
|
https://www.cell.com/heliyon/fulltext/S2405-8440(24)09824-4
|
https://www.mdpi.com/2673-8732/4/3/12
|
https://netdevconf.info/0x15/papers/32/paper-final.pdf
|
No
| null |
How does IP over Satellite help remote education?
|
IP over Satellite enables internet connectivity in remote regions where terrestrial networks are absent. This allows students to access online courses, digital libraries, and e-learning platforms. Satellite links provide stable connectivity, bridging the educational gap between urban and rural areas. The technology ensures that digital learning resources are accessible even in isolated locations, supporting continuous education and skill development.
|
IP over satellite
|
https://www.mdpi.com/1424-8220/18/10/3421
|
https://www.mdpi.com/1999-5903/2/3/282
|
https://novel-coronavirus.onlinelibrary.wiley.com/doi/abs/10.1002/9781119043508.ch3
|
No
| null |
How does IP over Satellite support disaster recovery?
|
In disasters, terrestrial networks often fail. IP over Satellite provides immediate, reliable communication for emergency teams and affected populations. It enables data exchange, coordination, and remote monitoring, ensuring continuity of critical services. Satellite connectivity plays a vital role in maintaining communication during emergencies, helping rescue operations and relief management.
|
IP over satellite
|
https://www.mdpi.com/1424-8220/18/10/3421
|
https://www.mdpi.com/1999-5903/2/3/282
|
https://novel-coronavirus.onlinelibrary.wiley.com/doi/abs/10.1002/9781119043508.ch3
|
No
| null |
What does a SatLife UT with a public IP address do?
|
A SatLife UT with a public IP address is able to send and receive SIP voice/video calls being actively registered in the RSGW SIP Proxy.
|
IP over satellite
|
https://www.mdpi.com/1424-8220/18/10/3421
|
https://www.mdpi.com/1999-5903/2/3/282
|
https://novel-coronavirus.onlinelibrary.wiley.com/doi/abs/10.1002/9781119043508.ch3
|
No
| null |
What security challenges exist in satellite IP networks, and how can data be protected?
|
Satellite networks cover wide areas, making them susceptible to interception and eavesdropping. Security measures include encryption of transmitted data, secure authentication protocols, and use of VPNs or firewalls to prevent unauthorized access.
|
IP over satellite
|
https://www.mdpi.com/1424-8220/18/10/3421
|
https://www.mdpi.com/1999-5903/2/3/282
|
https://novel-coronavirus.onlinelibrary.wiley.com/doi/abs/10.1002/9781119043508.ch3
|
No
| null |
Why is bandwidth management critical in IP over Satellite?
|
Bandwidth is limited in satellite systems. Efficient allocation ensures multiple users can access IP services without interference. Techniques like traffic prioritization, adaptive coding, and modulation optimize available bandwidth, improving throughput and service quality. Proper bandwidth management is essential for applications such as video streaming in satellite networks.
|
IP over satellite
|
https://www.mdpi.com/1424-8220/18/10/3421
|
https://www.mdpi.com/1999-5903/2/3/282
|
https://novel-coronavirus.onlinelibrary.wiley.com/doi/abs/10.1002/9781119043508.ch3
|
No
| null |
Why is IP over Satellite important for remote regions?
|
IP over Satellite is crucial for remote regions because it provides connectivity where terrestrial infrastructure is limited or absent. It enables access to online education, telemedicine, e-governance, and economic opportunities. Satellite connectivity also supports disaster recovery by maintaining communication when ground networks fail. Overall, it bridges the digital gap and allows people in isolated areas to access essential services and information.
|
IP over satellite
|
https://www.mdpi.com/1424-8220/18/10/3421
|
https://www.mdpi.com/1999-5903/2/3/282
|
https://novel-coronavirus.onlinelibrary.wiley.com/doi/abs/10.1002/9781119043508.ch3
|
No
| null |
A satellite IP link has bandwidth of 20 MHz and SNR = 10 (linear). Calculate maximum data rate using Shannon capacity
|
Capacity C = B × log₂(1 + SNR) = 20 × log₂(1 + 10) ≈ 20 × 3.459 ≈ 69.2 Mbps. This is the theoretical maximum rate under ideal conditions, helping engineers plan for sufficient bandwidth and modulation schemes for IP over Satellite networks.
|
IP over satellite
|
https://www.mdpi.com/1424-8220/18/10/3421
|
https://www.mdpi.com/1999-5903/2/3/282
|
https://novel-coronavirus.onlinelibrary.wiley.com/doi/abs/10.1002/9781119043508.ch3
|
Yes
|
Capacity C = B \times log_2(1 + SNR) = 20 \times log_2(1 + 10) ~ 20 \times 3
|
A satellite IP link has bandwidth of 20 MHz and SNR = 10 (linear). Calculate maximum data rate using Shannon capacity.
|
Capacity C = B × log₂(1 + SNR) = 20 × log₂(1 + 10) ≈ 20 × 3.459 ≈ 69.2 Mbps. This is the theoretical maximum rate under ideal conditions, helping engineers plan for sufficient bandwidth and modulation schemes for IP over Satellite networks.
|
IP over satellite
|
https://www.mdpi.com/1424-8220/18/10/3421
|
https://www.mdpi.com/1999-5903/2/3/282
|
https://novel-coronavirus.onlinelibrary.wiley.com/doi/abs/10.1002/9781119043508.ch3
|
Yes
|
Capacity C = B \times log_2(1 + SNR) = 20 \times log_2(1 + 10) ~ 20 \times 3
|
A satellite link has a C/N ratio of 15. Noise power is 2 W. What is the required signal power?
|
Signal Power = C/N × Noise Power = 15 × 2 = 30 W. This means the transmitted signal must be 30 W to maintain a C/N ratio of 15, ensuring clear communication. Maintaining the right C/N ratio is crucial in satellite IP systems to avoid errors and ensure reliable data delivery.
|
IP over satellite
|
https://www.mdpi.com/1424-8220/18/10/3421
|
https://www.mdpi.com/1999-5903/2/3/282
|
https://novel-coronavirus.onlinelibrary.wiley.com/doi/abs/10.1002/9781119043508.ch3
|
Yes
|
Signal Power = C/N \times Noise Power = 15 \times 2 = 30 W
|
A satellite link transmits 10 Mbps. Bandwidth available is 2 MHz. Find the required spectral efficiency.
|
Spectral Efficiency = Data Rate / Bandwidth = 10 Mbps / 2 MHz = 5 bits/Hz. This tells us how efficiently the satellite system uses its bandwidth to transmit IP data. Optimizing spectral efficiency is critical in satellite networks due to limited spectrum availability.
|
IP over satellite
|
https://www.mdpi.com/1424-8220/18/10/3421
|
https://www.mdpi.com/1999-5903/2/3/282
|
https://novel-coronavirus.onlinelibrary.wiley.com/doi/abs/10.1002/9781119043508.ch3
|
Yes
|
Spectral Efficiency = Data Rate / Bandwidth = 10 Mbps / 2 MHz = 5 bits/Hz
|
A satellite link transmits 50 Mbps over 10 MHz bandwidth. Calculate the spectral efficiency.
|
Spectral Efficiency = Data Rate / Bandwidth = 50 Mbps / 10 MHz = 5 bits/Hz. This indicates that each Hz of bandwidth carries 5 bits of information. Higher spectral efficiency allows more data to be transmitted using limited spectrum, which is vital in satellite IP networks where bandwidth is constrained.
|
IP over satellite
|
https://www.mdpi.com/1424-8220/18/10/3421
|
https://www.mdpi.com/1999-5903/2/3/282
|
https://novel-coronavirus.onlinelibrary.wiley.com/doi/abs/10.1002/9781119043508.ch3
|
Yes
|
Spectral Efficiency = Data Rate / Bandwidth = 50 Mbps / 10 MHz = 5 bits/Hz
|
A satellite link transmits data at 10 Mbps with a modulation scheme achieving 2 bits/Hz spectral efficiency. What is the required bandwidth?
|
Bandwidth = Data Rate / Spectral Efficiency = 10 Mbps / 2 bits/Hz = 5 MHz. This means 5 MHz of spectrum is needed to transmit 10 Mbps. Proper bandwidth allocation ensures reliable transmission without interference.
|
IP over satellite
|
https://www.mdpi.com/1424-8220/18/10/3421
|
https://www.mdpi.com/1999-5903/2/3/282
|
https://novel-coronavirus.onlinelibrary.wiley.com/doi/abs/10.1002/9781119043508.ch3
|
Yes
|
Bandwidth = Data Rate ÷ Spectral Efficiency
|
A satellite system transmits 100 Mbps using a 25 MHz channel. Find spectral efficiency.
|
Spectral Efficiency = Data Rate / Bandwidth = 100 ÷ 25 = 4 bits/Hz. This indicates each Hz of bandwidth carries 4 bits of information. Efficient use of spectral resources is crucial in satellite IP systems to maximize throughput and support multiple users with limited spectrum.
|
IP over satellite
|
https://www.mdpi.com/1424-8220/18/10/3421
|
https://www.mdpi.com/1999-5903/2/3/282
|
https://novel-coronavirus.onlinelibrary.wiley.com/doi/abs/10.1002/9781119043508.ch3
|
Yes
|
Spectral Efficiency = Data Rate / Bandwidth = 100 / 25 = 4 bits/Hz
|
A satellite transmits 25 Mbps over 5 MHz. Calculate spectral efficiency.
|
Spectral Efficiency = Data Rate / Bandwidth = 25 ÷ 5 = 5 bits/Hz. Efficient spectral use is vital for satellite IP networks with limited spectrum resources. Higher efficiency allows more users or higher data rates without increasing bandwidth.
|
IP over satellite
|
https://www.mdpi.com/1424-8220/18/10/3421
|
https://www.mdpi.com/1999-5903/2/3/282
|
https://novel-coronavirus.onlinelibrary.wiley.com/doi/abs/10.1002/9781119043508.ch3
|
Yes
|
Spectral Efficiency = Data Rate / Bandwidth = 25 / 5 = 5 bits/Hz
|
A satellite transmits at 5 Mbps using a 1 MHz bandwidth. Find the spectral efficiency.
|
Spectral Efficiency = Data Rate / Bandwidth = 5 Mbps / 1 MHz = 5 bits/Hz. High spectral efficiency allows more data transmission over limited bandwidth.
|
IP over satellite
|
https://www.mdpi.com/1424-8220/18/10/3421
|
https://www.mdpi.com/1999-5903/2/3/282
|
https://novel-coronavirus.onlinelibrary.wiley.com/doi/abs/10.1002/9781119043508.ch3
|
Yes
|
Spectral Efficiency = Data Rate ÷ Bandwidth
|
How does Doppler shift affect satellite handover?
|
Doppler shift changes carrier frequency due to relative motion, complicating signal synchronization and handover timing. Compensating algorithms are essential for accurate handover processes.
|
Handover procedure
|
https://www.cs.ou.edu/~atiq/papers/06-ComTutorials-pulak-satellite-handover-survey.pdf
|
https://arxiv.org/html/2507.07437v1
|
https://novotech.com/pages/satellite-handover
|
No
| null |
How does inter-satellite link (ISL) assist in handover?
|
ISL allows data and signaling to be relayed between satellites directly, enabling coordinated handover with reduced latency and improved link continuity, especially in large satellite constellations.
|
Handover procedure
|
https://arxiv.org/html/2507.07437v1
|
https://www.cs.ou.edu/~atiq/papers/06-ComTutorials-pulak-satellite-handover-survey.pdf
|
https://novotech.com/pages/satellite-handover
|
No
| null |
What challenges affect handovers in satellite systems?
|
Challenges include handover latency, prediction inaccuracies, Doppler shifts, signal blockage, and resource allocation. Efficient scheduling and prediction algorithms are critical to mitigate these.
|
Handover procedure
|
https://arxiv.org/html/2507.07437v1
|
https://www.cs.ou.edu/~atiq/papers/06-ComTutorials-pulak-satellite-handover-survey.pdf
|
https://novotech.com/pages/satellite-handover
|
No
| null |
What innovations are improving satellite handover procedures?
|
Use of machine learning for signal prediction, inter-satellite coordination, and enhanced scheduling algorithms optimize handover timing, reducing latency and improving user experience.
|
Handover procedure
|
https://arxiv.org/html/2507.07437v1
|
https://www.cs.ou.edu/~atiq/papers/06-ComTutorials-pulak-satellite-handover-survey.pdf
|
https://novotech.com/pages/satellite-handover
|
No
| null |
What is a spotbeam handover?
|
Spotbeam handover occurs when a user’s communication switches between different satellite beams covering adjacent geographic areas, commonly to maintain signal strength in GEO satellite systems.
|
Handover procedure
|
https://www.cs.ou.edu/~atiq/papers/06-ComTutorials-pulak-satellite-handover-survey.pdf
|
https://en.wikipedia.org/wiki/Handover
|
https://novotech.com/pages/satellite-handover
|
No
| null |
What is Conditional Handover (CHO) in satellite networks?
|
CHO pre-establishes connections with multiple potential target satellites allowing the user to switch based on optimal conditions, improving reliability and reducing latency during handover execution.
|
Handover procedure
|
https://arxiv.org/html/2507.07437v1
|
https://www.cs.ou.edu/~atiq/papers/06-ComTutorials-pulak-satellite-handover-survey.pdf
|
https://novotech.com/pages/satellite-handover
|
No
| null |
What role does the core network play in handover?
|
The core network manages path switching, resource allocation, and synchronization between old and new satellite links, ensuring data integrity and connectivity.
|
Handover procedure
|
https://arxiv.org/html/2507.07437v1
|
https://www.cs.ou.edu/~atiq/papers/06-ComTutorials-pulak-satellite-handover-survey.pdf
|
https://novotech.com/pages/satellite-handover
|
No
| null |
What is the importance of onboard error correction?
|
Onboard error correction improves the robustness of communication by detecting and correcting transmission errors within the satellite payload. This reduces the bit error rate in received signals, leading to higher quality and reliability of the communication link. Forward error correction (FEC) techniques are commonly employed here.
|
Onboard processing
|
https://itso.int/wp-content/uploads/2018/04/Basics-of-Satellite-Communications-1.pdf
|
https://gsaw.org/wp-content/uploads/2018/03/2018tutorial_d.pdf
|
https://ntrs.nasa.gov/api/citations/19870018278/downloads/19870018278.pdf
|
No
| null |
Why are higher frequency bands more susceptible to degradation?
|
Satellite communication links, particularly at high frequencies (e.g., Ku- and Ka-bands), are highly susceptible to signal degradation due to rain fade — the absorption and scattering of radio signals by precipitation such as rain, snow, or ice.
|
Satellite Bandwidth
|
https://www.mdpi.com/1424-8220/23/4/1872
|
https://www.mdpi.com/2079-9292/11/10/1534
|
https://ntrs.nasa.gov/api/citations/19980019442/downloads/19980019442.pdf
|
No
| null |
Why is the satellite bus important?
|
The satellite bus is important because it provides all the necessary support for the satellite to operate in space. It supplies power, manages thermal conditions, controls orientation, and handles data, allowing the payload to carry out the mission. Without a bus, the payload alone cannot function, as it requires these supporting systems to survive the harsh conditions of space and maintain communication with Earth. The bus ensures reliability, stability, and efficiency of satellite operations, making it a critical component. A well-designed bus improves mission success, extends satellite life, and supports diverse applications from communication to scientific observation.
|
Satellite bus
|
https://ieeexplore.ieee.org/abstract/document/5246694/
|
https://books.google.com/books?hl=en&lr=&id=atmxDwAAQBAJ&oi=fnd&pg=PR11&dq=Satellite+bus+research+article+pdf+in+communication&ots=7yaRwR31Oj&sig=QRcIneI1LofVlKBWBEPSmHvv8HA
|
https://ntrs.nasa.gov/api/citations/20180006794/downloads/20180006794.pdf
|
No
| null |
How does the impact of ionospheric scintillation vary with frequency, and what implications does this have for UHF transmissions compared to L-band?
|
Ionospheric scintillation is most significant in equatorial regions and during the equinoxes in March and September. Both ionospheric scintillation and Faraday rotation diminish as frequency increases, becoming nearly negligible at Ku-band and higher frequencies. In contrast, UHF transmissions may experience more severe impairments, necessitating an additional fade margin beyond what is required at L-band.
|
Link budget
|
https://www.sciencedirect.com/science/article/abs/pii/S0273117702007950
|
https://www.sciencedirect.com/science/article/pii/S2095809924001383
|
https://ntrs.nasa.gov/citations/19720033192
|
No
| null |
What role does the OrbComm satellite constellation play in the commercial VHF market, and what services does it provide?
|
From a commercial standpoint, the only notable VHF project is OrbComm, a low data rate LEO satellite constellation developed by Orbital Sciences Corporation. OrbComm offers a near-real-time messaging service to affordable handheld devices that are roughly the size of a small transistor radio.
|
Link budget
|
https://www.researchgate.net/publication/255631955_An_Overview_of_Major_Satellite_Systems
|
https://www.microwavejournal.com/articles/39512-architecture-of-orbcomm-little-leo-global-satellite-system-for-mobile-and-personal-communications
|
https://ntrs.nasa.gov/citations/19960022519
|
No
| null |
What are the benefits and drawbacks of using C-band for satellite communications?
|
C-band strikes a favorable balance between radio propagation characteristics and available bandwidth. It offers excellent service quality due to minimal fading from rain and ionospheric scintillation. However, a notable drawback is the relatively large size of the Earth station antennas required for this frequency band.
|
Link budget
|
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/92RS01307
|
https://link.springer.com/chapter/10.1007/978-981-16-8129-5_12
|
https://onlinelibrary.wiley.com/doi/10.1155/2014/741678
|
No
| null |
How does the availability of bandwidth and the use of directional antennas at frequencies above 3 GHz influence link budget considerations for wideband services?
|
Wideband services, such as Direct-to-Home (DTH) and broadband data services, can operate at frequencies above 3 GHz, where more than ten times the available bandwidth exists. Additionally, the use of directional ground antennas enhances the effective utilization of otherwise unusable orbital positions. As a result, some wideband services have started transitioning from the established C-band to the Ku- and Ka-bands.
|
Link budget
|
https://link.springer.com/chapter/10.1007/978-3-642-04260-7_7
|
https://link.springer.com/chapter/10.1007/978-981-97-6937-7_41
|
https://onlinelibrary.wiley.com/doi/abs/10.1002/sat.1158
|
No
| null |
How does capacity planning influence the number of base stations and transceivers in a network rollout?
|
Capacity planning is a crucial aspect of network rollout, as it determines the number of base stations needed and their respective capacities. The required number of base stations in a given area is established through coverage planning, while the number of transceivers needed is determined by capacity planning, which is directly linked to the frequency reuse factor. The frequency reuse factor refers to the number of base stations that can be deployed before the same frequency can be reused.
|
Link budget
|
https://link.springer.com/chapter/10.1007/0-306-47319-4_6
|
https://www.mdpi.com/1424-8220/23/21/8925
|
https://onlinelibrary.wiley.com/doi/epdf/10.1155/2017/4380676
|
No
| null |
How does Broadcasting Satellite Service (BSS) relate to link budget considerations in satellite communication systems?
|
Broadcasting Satellite Service (BSS) involves signals transmitted or retransmitted by space stations that are intended for direct reception by the general public. In the context of BSS, "direct reception" includes both individual and community reception.
|
Link budget
|
https://www.scribd.com/doc/57169385/Handbook-on-Satellite-Communications
|
https://studylib.net/doc/8725510/regulation-of-global-broadband-satellite-communications
|
https://onlinelibrary.wiley.com/doi/full/10.1155/2023/5977121
|
No
| null |
How does Mobile Satellite Service (MSS) relate to link budget considerations in satellite communication systems?
|
Mobile Satellite Service (MSS) facilitates communication between mobile Earth stations and one or more space stations, which may include multiple satellites connected via intersatellite links. This service can also encompass the feeder links required for its operation.
|
Link budget
|
https://www.scribd.com/doc/57169385/Handbook-on-Satellite-Communications
|
https://studylib.net/doc/8725510/regulation-of-global-broadband-satellite-communications
|
https://onlinelibrary.wiley.com/doi/full/10.1155/2023/5977121
|
No
| null |
What interfaces connect different 3GPP network elements?
|
Different interfaces in 3GPP architecture facilitate communication between network elements; for example, S1 connects eNodeB and MME for signaling, S11 connects MME and SGW, and S5/S8 link SGW to PGW for user data. In 5G, interfaces like N1, N2, and N3 connect AMF, SMF, and UPF respectively. These standardized interfaces ensure interoperability, efficient data routing, and signaling across the network components.
|
3gpp
|
https://www.3gpp.org/technologies/5g-system-overview
|
https://en.wikipedia.org/wiki/3GPP
|
https://open-cloud.github.io/arch.html
|
No
| null |
How does SNR influence data transmission quality?
|
The Signal-to-Noise Ratio (SNR) directly affects the clarity and accuracy of data transmission. When the SNR is high, the receiver can easily separate the signal from background noise, resulting in fewer errors and faster communication. In contrast, a low SNR can lead to packet loss and slower data transfer. Maintaining a strong SNR is essential for stable network performance, especially in wireless environments.
|
SNR
|
https://forum.huawei.com/enterprise/en/what-is-snr-and-how-to-improve-it/
|
https://scispace.com/pdf/performance-investigation-of-channel-noise-effect-in-data-xlnf1h286f.pdf
|
https://pmc.ncbi.nlm.nih.gov/articles/PMC10007584/
|
No
| null |
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