Recently Updated 3g Interview Questions Part – 2

Tell Me How Does Soft/softer Handover Work?

★ Soft/softer handover down-link:

UE rake receiver performs maximum ratio combining, i.e. UE combines multi-path signals and form a stronger signal.

★ Soft handover up-link:

RNC performs selection combining, i.e. RNC selects the better signal coming from multiple NodeB.

★ Softer handover up-link:

NodeB performs maximum ratio combining, i.e. NodeB rake receiver combines signals from different paths and forms a stronger signal

What Is Pole Capacity?

The uplink noise increases with the loading exponentially. When the up-link noise approaches infinity then no more users can be added to a cell – and the cell loading is close to 100% and has reached its pole capacity

Explain Sir?

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

Rscp Stands For?

RSCP stands for Received Signal Code Power – the energy per chip in CPICH averaged over 512 chips.

Do You Know How Does Tma Work?

A TMA reduces system noise, improves up-link sensitivity and leads to longer UE battery life. Sensitivity is the minimum input power needed to get a suitable signal-to-noise ratio (SNR) at the output of the receiver.

It is determined by receiver noise figure, thermo noise power and required SNR. Thermo noise power is determined by bandwidth and temperature, SNR is determined by modulation technique, therefore the only variable is noise figure.

Explain Typical Maximum Path Loss?

The maximum path loss is dependent on the service and vendor recommendations; typically it is in between 135 to 140dB for urban areas and between 150 to 160dB for rural areas.

Do You Know What Is A Typical Antenna Gain?

The antenna gain depends on antenna model; in link budget we use around 17dBi.

Tell Me What Is A Typical Nodeb Maximum Output Power?

The maximum NodeB output power is usually 20W or 40W, that is, 43dBm or 46dBm.

What Is A Typical Nodeb Sensitivity Level?

The service and load determines the NodeB sensitivity; in general, in a no-load condition, the sensitivity is between -115dBm to -125dBm.

For Ericsson, the NodeB sensitivity level is calculated at around:

CS12.2: -124 dBm ,PS-64: -119 dBm, PS-128: -115 dBm, PS-384: -115 dBm

Explain Several Event In 3g?

★ Event 1A:

UTRAN will add the new cell in the UE’s active cell list and will send an ACTIVE SET UPDATE message.

★ Event 1B:

UTRAN will send ACTIVE SET UPDATE message to remove the cell from UE’s active set.

★ Event 1C:

UTRAN will send ACTIVE SET UPDATE message that will remove one or more cells and will add one or more cells. The only restriction for 1C is that there should be atleast one radio link that is not affected by the procedure.

Tell Me What Is Typical Tma Gain?

TMA typically has a 12 dB gain; however, the effective gain comes from noise figure reduction and the gain is close or equivalent to the feeder loss.

What Is Soft Handover?

Soft handover means that the radio links are added and removed in a way that the UE always keeps at least one radio link to the UTRAN.

Soft handover is performed by means of macro diversity, which refers to the condition that several radio links are active at the same time. Normally soft handover can be used when cells operated on the same frequency are changed.

What Is Hard Handover?

Hard handover means that all the old radio links in the UE are removed before the new radio links are established. Hard handover can be seamless or non-seamless. Seamless hard handover means that the handover is not perceptible to the user. In practice a handover that requires a change of the carrier frequency (inter-frequency handover) is always performed as hard handover.

What Are The Types Of Hand Over?

★ Hard Handover
★ Soft Handover

Explain Iden(integrated Digital Enhanced Network)?

A wireless technology for Motorola
It has the capabilities of digi-cellular phone, 2 way radio, alphanumeric pager and data modem / fax modem in a single network
Operational bands are 800 MHz, 900 MHz and 1.5 GHz
iDEN is based on TDMA(Time Division Multiple Access) and GSM architecture
For voice compression it uses Motorola’s Vector Sum Excited Linear Predictors vocoder
For delivering 64 KBPS over a 25 KHz channel, it uses QAM modulation.
iDEN is designed to serve the mobile user for accessing information quickly without carrying several devices.

What Is Hlr (home Location Register)?

For GSM and CDMA wireless networks
It’s responsibility is to authenticate and authorize subscribers and their services.

Explain Gprs (general Packet Radio Service)?

Packet oriented mobile data service available to the users of 2G cellular systems.
It is global system for communicating through mobile phones using GSM as well as in 3G systems.
GPRS data transfer is charged per MB of traffic transferred, where as in circuit switching, data transfer is charged per minute of connection time
GPRS is better packet switching service, as opposed to circuit switching.
2G cellular systems are combined with GPRS and known as 2.5 G.
Provides moderate speed data transfer by using unused TDMA channels, such as GSM.

Explain Gsm (global System For Mobile Communications)?

Most popular standard for mobile telephony systems, originated from Group Special Mobile
The ubiquity of GSM enables the international roaming arrangements among mobile phone operators.
Both signaling and speech channels are digital, and thus GSM is considered as 2G mobile phone system.
GSM standard benefited customers the ability to roam and switch carriers without replacing the hand sets and network operators.
GSM implements low-cost implementation of Short Message Service

Can You Please Explain The Difference Between 3g And 2g?

Packet data speed is higher in 3G, and it is up to 384 KBPS
Voice and sms speed is also 384 KBPS in 3G
2G utilizes different switching techniques for voice and data, where as 3G uses single switching, irrespective of data
3G has at least 2MB of data link of a mobile, where in 2G the data rate is in KBPS
3G has WiMAX facility for faster VOIP and internet
2G uses GSM TDMA technology with narrow band 200 KHz.
3G uses CD-MA technology with broadband 5 MHz, with same frequency carrier and time.

Explain The Disadvantages Of 3g?

The cost of cellular infrastructure , upgrading base stations is very high
Needs different handsets.
Roaming and data/voice work together has not yet been implemented
Power consumption is high
Requires closer base stations and are expensive
Spectrum-license costs, network deployment costs and handset subsidies subscribers are tremendous.

Explain The Advantages Of 3g?

Overcrowding is relieved in existing systems with radio spectrum
Bandwidth, security and reliability are more
Provides interoperability among service providers
Availability of fixed and variable rates
Support to devices with backward compatibility with existing networks
Always online devices – 3G uses IP connectivity which is packet based
Rich multi media services are available

What Is Evolution-data Optimized?

Evolution-Data Optimized or Evolution-Data only, abbreviated as EV-DO or EVDO and often EV, is a telecommunications standard for the wireless transmission of data through radio signals, typically for broadband Internet access.

It uses multiplexing techniques including code division multiple access (CDMA) as well as time division multiple access (TDMA) to maximize both individual user’s throughput and the overall system throughput. It is standardized by 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards.