Interview Questions.

Question 1. What Is A Typical Nodeb Sensitivity Level?

Answer :

The provider and cargo determines the NodeB sensitivity; in fashionable, in a no-load situation, the sensitivity is between -115dBm to -125dBm. For Ericsson, the NodeB sensitivity stage is calculated at round:

CS12.2: -124 dBm.
PS-sixty four: -119 dBm.
PS-128: -one hundred fifteen dBm.
PS-384: -115 dBm.
Question 2. What Is A Typical Ue Sensitivity Level?

Answer :

The service and load determines the UE sensitivity; in popular, in no-load circumstance, the sensitivity is among -105dBm and -120dBm. For Ericsson, the UE sensitivity level is calculated at round:

CS12.2: -119 dBm.
PS-sixty four: -112 dBm.
PS-128: -a hundred and ten dBm.
PS-384: -a hundred and five dBm.
HSDPA: -ninety five dBm.
Networking Interview Questions
Question 3. What Is A Typical Nodeb Maximum Output Power?

Answer :

The maximum NodeB output energy is generally 20W or 40W, that is, 43dBm or 46dBm.

Question four. What Is Ue Maximum Transmit Power In Your Link Budget?

Answer :

21dBm.

Networking Tutorial
Question five. What Is A Typical Antenna Gain?

Answer :

The antenna advantage depends on antenna version; in hyperlink budget we use round 17dBi.

GSM Interview Questions
Question 6. What Is A Typical Maximum Path Loss?

Answer :

The maximum route loss is dependent on the provider and dealer tips; generally it's far in between a hundred thirty five to 140dB for urban regions and among one hundred fifty to 160dB for rural areas.

Question 7. What Is Difference Between Dbi And Dbd?

Answer :

dBi is the gain in dB from isotropic source; dBd is the advantage from a dipole source.
DBd + 2.15 = dBi. 

GSM Tutorial Wireless Interview Questions
Question 8. What Is The Difference Between Db And Dbm?

Answer :

dBm is a unit of strength stage, measured in milli-watts in logarithm scale, this is, dBm = 10 * log(W*1000) in which W is the energy in Watts dB is not a unit, it's miles the distinction in dBm.

Question 9. What Is 0dbm?

Answer :

0dBm = 1 milli-watt. 

4G Interview Questions
Question 10. What Are The Pros And Cons (blessings And Disadvantages) Of Tma?

Answer :

On the upside, a TMA reduces system noise, improves uplink sensitivity and ends in longer UE battery life. On the disadvantage, TMA imposes an additional insertion loss (typically zero.5dB) at the downlink and increases web site installation and maintenance complexity.

UMTS Tutorial
Question 11. What Is Typical Tma Gain?

Answer :

TMA normally has a 12 dB gain; but, the powerful benefit comes from noise figure discount and the gain is near or equal to the feeder loss.

Wideband Code Division Multiple Access (WCDMA) Interview Questions
Question 12. Why Tma Are Installed At The Top Near The Antenna And Not The Bottom Near The Nodeb?

Answer :

Based on Friis Equation, having a TMA near the BTS can have the pinnacle jumper and important feeder losses (noise figures) cascaded in and a TMA will now not be capable of help suppress the losses.

Networking Interview Questions
Question thirteen. What Is Umts Chip Rate?

Answer :

three.84MHz. 

JUnit Tutorial
Question 14. What Is Processing Gain?

Answer :

Processing advantage is the ratio of chip rate over information bit fee, normally represented in decibel (dB) scale. For example, with three.84MHz chip rate and 12.2k information charge, the processing gain is: 
PG12.2k = 10 * log (three,840,000 / 12,two hundred) = 25dB

Question 15. What Are The Processing Gains For Cs And Ps Services?

Answer :

CS12.2: 25dB
PS-64: 18dB
PS-128: 15dB
PS-384: 10dB
HSDPA: 2dB 
JUnit Interview Questions
Question 16. What Is Eb/no?

Answer :

By definition Eb/No is power bit over noise density, i.E. Is the ratio of the power per information bit to the energy spectral density (of interference and noise) after dispreading.

Eb/No = Processing Gain + SIR

For example, if Eb/No is 5dB and processing advantage is 25dB then the SIR have to be -20dB or higher.

Question 17. What Are The Eb/no Targets In Your Design?

Answer :

The Eb/No targets are dependent on the provider:

On the uplink, typically CS is 5 to 6dB and PS is three to 4dB – PS is about 2dB decrease.
On the downlink, normally CS has 6 to 7dB and PS is five to 6dB – PS is about 1dB lower.
3G Interview Questions
Question 18. Why Is Eb/no Requirement Lower For Ps Than For Cs?

Answer :

PS has a better blunders correction capability and can utilize retransmission, therefore it is able to find the money for to a lower Eb/No. CS is real-time and can not tolerate postpone so it desires a higher Eb/No to keep a more potent RF link. 

GSM Interview Questions
Question 19. What Is Ec/io?

Answer :

Ec/Io is the ratio of the strength in line with chip in CPICH to the total acquired strength density (along with CPICH itself).

Question 20. Sometimes We Say Ec/io And Sometimes We Say Ec/no, Are They Different?

Answer :

Io = own mobile interference + surrounding cellular interference + noise density
No = surrounding cellular interference + noise density
That is, Io is the whole acquired electricity density which includes CPICH of its personal mobile, No is the total obtained energy density except CPICH of its personal cellular. Technically Ec/Io must be the correct dimension but, due to gadget functionality, Ec/No is certainly measured. In UMTS, Ec/No and Ec/Io are regularly used interchangeably.

Progress 4GL Interview Questions
Question 21. What Is Rscp?

Answer :

RSCP stands for Received Signal Code Power – the electricity in step with chip in CPICH averaged over 512 chips.

Question 22. What Is Sir?

Answer :

SIR is the Signal-to-Interference Ratio – the ratio of the strength in dedicated physical manipulate channel bits to the energy density of interference and noise after dispreading.

Question 23. What Is The Loading Factor In Your Design?

Answer :

The designed loading typically is 50%; but, on occasion a service may additionally need to layout up to seventy five% load. 

RF Engineer Interview Questions
Question 24. What Is Typical Pole Capacity For Cs-12.2, Ps-sixty four, Ps-128 And Ps-384?

Answer :

With same assumptions as above:

CS-12.2k: a hundred and twenty.6 (UL), sixty four.1 (DL).
PS-64k: 34.8 (UL), 12.Eight(DL).
PS-128k: sixteen.2 (UL), 8.4 (DL).
PS-384k: sixteen.2 (UL), 2.Eight (DL).
PS-384k has only 128k at the uplink, therefore the uplink potential is the equal for both.

Wireless Interview Questions
Question 25. How Many Types Of Handovers Are There In Umts?

Answer :

Soft handover, softer handover, inter-frequency handover, inter-RAT handover, inter-RAT mobile trade (UE shifting out of UMTS insurance into GSM/GPRS/EGDGE coverage).

Question 26. What Is Soft Handover And Softer Handover?

Answer :

Soft handover: while a UE is hooked up to cells owned by means of one of a kind NodeB.
Softer handover: when a UE is hooked up to cells owned by way of the same NodeB.
Multiprotocol Label Switching (MPLS) Interview Questions
Question 27. How Does Soft/softer Handover Work?

Answer :

Soft/softer handover downlink: UE rake receiver performs maximum ratio combining, i.E. UE combines multi-path indicators and shape a stronger sign.

Soft handover uplink: RNC plays selection combining, i.E. RNC selects the higher signal coming from a couple of NodeB.
Softer handover uplink: NodeB performs most ratio combining, i.E. NodeB rake receiver combines alerts from unique paths and forms a stronger signal.
4G Interview Questions
Question 28. Why Is There “smooth Handover Gain”?

Answer :

Soft handover benefit comes from the following:

Macro range gain over slow fading.
Micro variety advantage over rapid fading.
Downlink load sharing over a couple of RF hyperlinks.
By maintaining a couple of links every link should transmit at a decrease energy, ensuing in decrease interference consequently a gain.

Question 29. Brief Describe The Advantages And Disadvantages Of Soft Handover?

Answer :

Advantages:

Overcome fading thru macro variety.
Reduced Node B strength which in flip decreases interference and increases capability.
Reduced UE strength (up 4dB), lowering interference and increasing battery existence.
Disadvantages:

UE using numerous radio links requires more channelization codes, and greater resources at the Iub and Iur interfaces.
LTE Rf Planning Optimization For 4g Interview Questions
Question 30. What Are Fast Fading And Slow Fading?

Answer :

Fast fading is also known as multi-direction fading, because of multi-course propagation. When multi-route signals arriving at a UE, the positive and detrimental levels create a variant in signal electricity.Slow fading is also referred to as shadowing. When a UE actions away from a cellular the signal electricity drops down slowly.

Question 31. What Are Fast Fading Margin And Slow Fading Margin?

Answer :

To component within the rapid fading and slow fading, we need to have a margin within the link finances and they're referred to as speedy fading margin and slow fading margin. In hyperlink finances, the short fading margin is commonly set to two-3; sluggish fading margin is about to 7-10.

Question 32. What Is A Typical Soft Handover Gain In Your Link Budget?

Answer :

CS-12.2k: 3dB (UL), 2dB (DL).
PS-64k: 1dB (UL), 0dB (DL).
PS-128k: 1dB (UL), 0dB (DL).
PS-384k: 1dB (UL), 0dB (DL).
Gsm RF Engineer Interview Questions
Question 33. What Is The Percentage In Time A Ue Is Expected To Be In Soft Or Softer Handover?

Answer :

Typically a UE must be in smooth handover mode at no extra than 35 to forty% of the time; in softer handover mode at approximately five% of the time.

Wideband Code Division Multiple Access (WCDMA) Interview Questions
Question 34. What Is A Typical Eirp?

Answer :

The EiRP depends NodeB transmit energy, cable and connector loss and antenna advantage. With a pattern device of 43dBm transmit energy, a 3dB cable and connector loss and a 17dBi antenna advantage, the EiRP = 43 – 3 + 17 = 57dBm.

Question 35. How Much Power Usually A Nodeb Is Allocated To Control Channels?

Answer :

The electricity allocated to control channels may rely on device vendor recommendation. Typically no more than 20% of the whole NodeB energy is allocated to control channels, including CPICH. However, if HSDPA is deployed on the equal carrier then the whole energy allocated to control channel may fit up to 25 to 30% due to the extra HSDPA manipulate channels required.

Question 36. What Is A Typical Cpich Power?

Answer :

CPICH energy generally takes approximately 10% of the overall NodeB electricity. For a 20W (43dBm) NodeB, CPICH is round 2W (33dBm).In urban areas in which in-constructing insurance is looked after by way of in-constructing installations, the CPICH may additionally sometimes go as low as 5% due to the fact:

The coverage place is small for the reason that users are near the site.
More energy may be allotted to visitors channels.
JUnit Interview Questions
Question 37. How Much Is Your Hsdpa (max) Link Power?

Answer :

HSDPA hyperlink strength is typically four to 5dB underneath the maximum NodeB maximum output power. For instance, for 43dBm maximum NodeB electricity the HSDPA link electricity is 39dBm.

Question 38. Consider Downlink Only, What Are The Major Components In Calculating Maximum Path Loss, Starting From Nodeb?

Answer :

NodeB CPICH transmit power.
Jumper and feeder connector loss.
Antenna benefit.
Over-the-air loss.
Building / car penetration loss.
Body loss, and so on.,
Question 39. What Is Maximum Path-loss?

Answer :

The maximum course-loss is how plenty sign is allowed to drop from a transmitter to a receiver and continues as exact sign.

Question 40. Simple Link Budget: With A 30dbm Cpich And A -100dbm Ue Sensitivity, Ignoring Anything In Between, What Is The Maximum Path Loss?

Answer :

30 – (–a hundred) = 30 + a hundred = 130dB.

3G Interview Questions
Question forty one. Suppose I Have A Maximum Path-loss Of 130dbm, What Is The New Path-loss If A 5db Body Loss Is Added?

Answer :

125dB.

Question 42. What Is Channelization Code?

Answer :

Channelization codes are orthogonal codes used to spread the sign and for this reason provides channel separation, that is, channelization codes are used to split channels from a cellular.

Progress 4GL Interview Questions
Question 43. How Many Channelization Codes Are Available?

Answer :

The number of channelization codes available is dependent on the duration of code. In the uplink the duration is defined as among four and 256. In the downlink the period is defined as among four and 512.

Question 44. Are Channelization Codes Mutually Orthogonal? If So, Why Is “orthogonality Factor” Required In The Link Budget?

Answer :

Yes, channelization codes are jointly orthogonal. Nonetheless, due to multi-route with variable time put off, channels from the identical mobile are not flawlessly orthogonal and might intervene with every other. A “Downlink Orthogonality Factor”, commonly 50-60%, is therefore wanted inside the link price range to account for the interference – and subsequently reduces pole potential.

Question forty five. What Is Scrambling Code? How Many Scrambling Codes There Are?

Answer :

Scrambling codes are used to split cells and UEs from each different, this is, each mobile or UE ought to have a unique scrambling code. There are 512 scrambling codes at the downlink and hundreds of thousands on the uplink.

Question forty six. What Is Scrambling “code Group”?

Answer :

The 512 scrambling codes are divided into 64 code organizations – every code institution has 8 scrambling codes. Code organization i (i = 0 to sixty three) has codes from i*8 to (i+1)*eight-1, i.E. (zero-7) (8-15)…(504-511).

Question forty seven. Do You Divide Scrambling Code Groups Into Subgroups? Please Give An Example.

Answer :

Yes, we divide the 64 code groups into subgroups:

Macro layer group: 24 code groups reserved for macro (out of doors) websites.
Micro layer group: 16 code companies reserved for micro (in-constructing) websites.
Expansion institution: 24 code agencies reserved for destiny growth websites.
Question forty eight. Which Service Usually Needs Higher Power, Cs Or Ps?

Answer :

Consider downlink and take CS-12.2 and PS-384k for example. The processing gain is 25 for CS-12.2 and 10 for PS-384. The Eb/No requirement is 7 for CS-12.2 and five for PS-384. Therefore the energy requirement is higher for CS-12.2 than PS-384.

Question forty nine. What Is Eb/no Requirement For Hsdpa?

Answer :

The Eb/No requirement for HSDPA varies with consumer bit price (statistics price), commonly 2 for 768kbps and five for 2Mbps.

Question 50. What Is “noise Rise”? What Does A Higher Noise Rise Mean In Terms Of Network Loading?

Answer :

For each new person added to the carrier, extra noise is introduced to the community. That is, every new consumer causes a “noise rise”. In principle, the “noise upward thrust” is described as the ratio of overall acquired wideband strength to the noise strength. Higher “noise upward thrust” cost implies more users are allowed on the network, and every consumer has to transmit higher electricity to triumph over the higher noise level. This means smaller course loss may be tolerated and the cellular radius is reduced. To summarize, a higher noise upward thrust manner higher ability and smaller footprint, a lower noise upward push method smaller capability and larger footprint.