Interview Questions.

Question 1. What Is Lte?

Answer :

LTEi (Long Term Evolution) is initiated with the aid of 3GPPi to enhance the cell smartphone fashionable to cope with destiny era evolutions and desires.

Question 2. What Is Goal Of Lte?

Answer :

The goals for LTE encompass improving spectral efficiency, reducing prices, enhancing offerings, making use of new spectrum and reformed spectrum possibilities, and better integration with different open standards.

Networking Interview Questions
Question 3. What Speed Lte Offers?

Answer :

LTE affords downlink height quotes of at least 100Mbit/s, 50 Mbit/s in the uplink and RAN (Radio Access Network) spherical-journey instances of less than 10 ms.

Question four. What Is Lte Advanced?

Answer :

LTE requirements are in matured country now with release eight frozen. While LTE Advanced is still below works. Often the LTE fashionable is seen as 4G fashionable which isn't always proper. 3.9G is greater perfect for LTE. So why it is not 4G? Answer is pretty simple - LTE does not satisfy all requirements of ITU 4G definition.

Brief History of LTE Advanced: The ITU has delivered the term IMT Advanced to discover cell systems whose abilties go beyond those of IMT 2000. The IMT Advanced systems shall provide nice-in-class performance attributes including top and sustained statistics rates and corresponding spectral efficiencies, capacity, latency, normal network complexity and first-rate-of-service management. The new abilties of those IMT-Advanced structures are envisaged to deal with a wide variety of supported facts rates with goal height statistics prices of as much as approximately one hundred Mbit/s for high mobility and up to approximately 1 Gbit/s for low mobility.

Networking Tutorial
Question five. What Is Lte Architecture?

Answer :

The advanced structure contains E-UTRAN (Evolved UTRAN) at the get admission to facet and EPC (Evolved Packet Core) at the core aspect.

Procurement Interview Questions
Question 6. What Is Eutran?

Answer :

The E-UTRAN (Evolved UTRAN) consists of eNBs, supplying the E-UTRA person plane (PDCP/RLC/MAC/PHY) and manipulate aircraft (RRC) protocol terminations in the direction of the UE. The eNBs are interconnected with every other via the X2 interface. The eNBs also are linked through the S1 interface to the EPC (Evolved Packet Core), extra specifically to the MME (Mobility Management Entity) with the aid of the S1-MME and to the Serving Gateway (S-GW) via the S1-U.

Question 7. What Are Lte Interfaces?

Answer :

The following are LTE Interfaces : (Ref: TS 23.401 v 841)

S1-MME :- Reference point for the manage plane protocol among E-UTRAN and MME.
S1-U:- Reference point among E-UTRAN and Serving GW for the per bearer person aircraft tunnelling and inter eNodeB route switching for the duration of handover.
S3:- It enables person and bearer facts change for inter 3GPP get entry to network mobility in idle and/or active country.
S4:- It offers associated manipulate and mobility help between GPRS Core and the 3GPP Anchor feature of Serving GW. In addition, if Direct Tunnel isn't always installed, it presents the user aircraft tunnelling.
S5:- It affords person aircraft tunnelling and tunnel control among Serving GW and PDN GW. It is used for Serving GW relocation due to UE mobility and if the Serving GW needs to connect to a non-collocated PDN GW for the required PDN connectivity.
S6a:- It permits switch of subscription and authentication facts for authenticating/authorizing consumer access to the evolved machine (AAA interface) among MME and HSS.
Gx:- It presents transfer of (QoS) coverage and charging guidelines from PCRF to Policy and Charging Enforcement Function (PCEF) within the PDN GW.
S8:- Inter-PLMN reference factor providing person and control aircraft between the Serving GW within the VPLMN and the PDN GW in the HPLMN. S8 is the inter PLMN variation of S5.
S9:- It offers switch of (QoS) coverage and charging control statistics between the Home PCRF and the Visited PCRF as a way to support nearby breakout characteristic.
S10:- Reference point among MMEs for MME relocation and MME to MME facts transfer.
S11:- Reference point among MME and Serving GW.
S12:- Reference factor among UTRAN and Serving GW for consumer aircraft tunnelling whilst Direct Tunnel is mounted. It is primarily based on the Iu-u/Gn-u reference factor the use of the GTP-U protocol as described between SGSN and UTRAN or respectively among SGSN and GGSN. Usage of S12 is an operator configuration alternative.
S13:- It enables UE identity test procedure between MME and EIR.
SGi:- It is the reference point between the PDN GW and the packet statistics community. Packet statistics network may be an operator outside public or private packet records network or an intra operator packet facts community, e.G. For provision of IMS offerings. This reference point corresponds to Gi for 3GPP accesses.
Rx:- The Rx reference factor resides between the AF and the PCRF in the TS 23.203.
SBc:- Reference point among CBC and MME for warning message shipping and manage capabilities.
UMTS Tutorial Mac OS X Deployment Interview Questions
Question 8. What Are Lte Network Elements?

Answer :

eNB : eNB interfaces with the UE and hosts the PHYsical (PHY), Medium Access Control (MAC), Radio Link Control (RLC), and Packet Data Control Protocol (PDCP) layers. It additionally hosts Radio Resource Control (RRC) capability corresponding to the manage plane. It performs many functions such as radio aid control, admission control, scheduling, enforcement of negotiated UL QoS, mobile statistics broadcast, ciphering/deciphering of user and manipulate aircraft data, and compression/decompression of DL/UL person plane packet headers.

Mobility Management Entity : manages and stores UE context (for idle nation: UE/consumer identities, UE mobility country, person security parameters). It generates temporary identities and allocates them to UEs. It exams the authorization whether or not the UE may additionally camp at the TA or at the PLMN. It additionally authenticates the user. 

Serving Gateway : The SGW routes and forwards consumer statistics packets, even as also performing because the mobility anchor for the consumer aircraft in the course of inter-eNB handovers and because the anchor for mobility among LTE and other 3GPP technologies (terminating S4 interface and relaying the site visitors between 2G/3G structures and PDN GW).

Packet Data Network Gateway: The PDN GW presents connectivity to the UE to outside packet facts networks through being the point of go out and entry of visitors for the UE. A UE may additionally have simultaneous connectivity with multiple PDN GW for getting access to a couple of PDNs. The PDN GW performs policy enforcement, packet filtering for each user, charging assist, lawful Interception and packet screening.

Question nine. What Are Lte Protocols & Specifications?

Answer :

In LTE architecture, center network includes Mobility Management Entity (MME), Serving Gateway  (SGW), Packet Data Network Gateway (PDN GW) where as E-UTRAN has E-UTRAN NodeB (eNB).

Protocol hyperlinks are as beneath

Air Interface Physical Layer
GPRS Tunnelling Protocol User Plane (GTP-U)
GTP-U Transport
Medium Access Control (MAC)
Non-Access-Stratum (NAS) Protocol
Packet Data Convergence Protocol (PDCP)
Radio Link Control (RLC)
Radio Resource Control (RRC)
S1 Application Protocol (S1AP)
S1 layer 1
S1 Signalling Transport
X2 Application Protocol (X2AP)
X2 layer 1
X2 Signalling Transport
UMTS Interview Questions
Question 10. What Is Volga?

Answer :

VoLGA stands for "Voice over LTE via Generic Access". The VoLGA carrier resembles the 3GPP Generic Access Network (GAN). GAN offers a controller node - the GAN controller (GANC) - inserted among the IP get admission to community (i.E., the EPS) and the 3GPP core community. 

The GAN presents an overlay get admission to among the terminal and the CS core with out requiring specific upgrades or assist inside the community it traverses. This affords a terminal with a 'digital' connection to the core community already deployed by using an operator. The terminal and community hence reuse most of the present mechanisms, deployment and operational components.

SIP Tutorial
Question eleven. What Is Cs Fallback In Lte?

Answer :

LTE generation helps packet primarily based services only, but 3GPP does specifies fallback for circuit switched services as well. To attain this LTE structure and network nodes require additional functionality, this blog is an try and provide evaluate for identical.

In LTE architecture, the circuit switched (CS) fallback in EPS enables the provisioning of voice and traditional CS-area services (e.G. CS UDI video/ SMS/ LCS/ USSD). To provide these offerings LTE reuses CS infrastructure while the UE is served by means of E UTRAN.

Routing Protcol Interview Questions
Question 12. How Does Lte Security Works?

Answer :

The following are some of the principles of 3GPP E-UTRAN security based on 3GPP Release eight specifications:

The keys used for NAS and AS protection shall be dependent on the set of rules with which they may be used.
The eNB keys are cryptographically separated from the EPC keys used for NAS protection (making it impossible to use the eNB key to figure out an EPC key).
 The AS (RRC and UP) and NAS keys are derived in the EPC/UE from key cloth that was generated by a NAS (EPC/UE) degree AKA method (KASME) and recognized with a key identifier (KSIASME).
The eNB key (KeNB) is sent from the EPC to the eNB while the UE is coming into ECM-CONNECTED country (i.E. All through RRC connection or S1 context setup).
Networking Interview Questions
Question thirteen. What Is Ip Multimedia Subsystem (ims)?

Answer :

The 3GPP IP Multimedia Subsystem (IMS) generation affords an architectural framework for turning in IP based totally multimedia services. IMS permits telecom provider carriers to provide a brand new era of rich multimedia offerings throughout both circuit switched and packet switched networks. IMS offers access to IP based services unbiased of the access network e.G. Wi-fi access (GPRS, 3GPP’s UMTS, LTE, 3GPP2’s CDMA2000) and fixed networks (TISPAN’s NGN)

IMS defines a structure of logical elements the usage of SIP for name signaling between community factors and Provides a layered technique with described carrier, manage, and shipping planes. Some of IMS high degree necessities are stated below:

The application plane presents an infrastructure for the provision and management of services, subscriber configuration and identification management and defines popular interfaces to common capability.

The IMS manage plane handles the call related signaling and controls transport aircraft. Major detail of manipulate aircraft is the Call Session Control Function (CSCF) , which comprises Proxy-CSCF (P-CSCF),  Interrogating-CSCF (I-CSCF) and Serving-CSCF (S-CSCF). The CSCF (Call/Session Control Function) is largely a SIP server.

The IMS delivery plane presents a middle IP network with get right of entry to from subscriber device over wi-fi or wireline networks.

Question 14. How Does Measurements Work In Lte?

Answer :

In LTE E-UTRAN measurements to be accomplished by way of a UE for mobility are categorised as below

Intra-frequency E-UTRAN measurements
Inter-frequency E-UTRAN measurements
Inter-RAT measurements for UTRAN and GERAN
Inter-RAT measurements of CDMA2000 HRPD or 1xRTT frequencies
Question 15. What Is Automatic Neighbour Relation?

Answer :

According to 3GPP specs, the purpose of the Automatic Neighbour Relation (ANR) capability is to relieve the operator from the weight of manually dealing with Neighbor Relations (NRs). This function might operators attempt to provision.

Network Administrator Interview Questions
Question 16. How Does Intra E-utran Handover Is Performed?

Answer :

Intra E-UTRAN Handover is used handy over a UE from a supply eNodeB to a goal eNodeB using X2 whilst the MME is unchanged. In the situation defined here Serving GW is likewise unchanged. The presence of IP connectivity among the Serving GW and the source eNodeB, in addition to between the Serving GW and the target eNodeB is believed.

The intra E-UTRAN HO in RRC_CONNECTED state is UE assisted NW managed HO, with HO guidance signalling in E-UTRAN.

Question 17. How Does Policy Control And Charging Works In Lte?

Answer :

A crucial element in LTE network is the coverage and charging control (PCC) function that brings together and complements capabilities from in advance 3GPP releases to supply dynamic manipulate of policy and charging on a consistent with subscriber and in keeping with IP drift foundation.

LTE Evolved Packet Core (EPC) EPC includes a PCC architecture that provides support for excellent-grained QoS and enables software servers to dynamically manage the QoS and charging necessities of the offerings they supply. It additionally gives improved assist for roaming. Dynamic control over QoS and 

charging will help operators monetize their LTE  investment by way of supplying clients with a spread of QoS and charging options while deciding on a carrier.

The LTE PCC functions include:

PCRF (coverage and charging guidelines characteristic) presents coverage manipulate and go with the flow based charging control choices.
PCEF (policy and charging enforcement feature) carried out within the serving gateway, this enforces gating and QoS for man or woman IP flows at the behalf of
the PCRF. It also provides utilization size to assist charging
OCS (online charging gadget) provides credit score management and offers credit to the PCEF based totally on time, site visitors volume or chargeable events.
OFCS (off-line charging system) gets occasions from the PCEF and generates charging facts records (CDRs) for the billing device.
4G Interview Questions
Question 18. What Is Son & How Does It Work In Lte?

Answer :

Self-configuring, self-optimizing wireless networks isn't always a new idea but because the cellular networks are evolving toward 4G LTE networks, introduction of self configuring and self optimizing mechanisms is needed to minimize operational efforts. A self optimizing feature would increase community performance and exceptional reacting to dynamic tactics in the network.

This could reduce the existence cycle cost of walking a network via eliminating manual configuration of system on the time of deployment, proper through to dynamically optimizing radio network overall performance at some stage in operation. Ultimately it will reduce the unit value and retail fee of wi-fi data offerings.

Procurement Interview Questions
Question 19. How Does Network Sharing Works In Lte?

Answer :

3GPP community sharing architecture lets in special middle community operators to hook up with a shared radio get entry to network. The operators do now not only proportion the radio network elements, but may additionally proportion the radio sources themselves.

Question 20. How Does Timing Advance (ta) Works In Lte?

Answer :

In LTE, while UE wish to set up RRC connection with eNB, it transmits a Random Access Preamble, eNB estimates the transmission timing of the terminal based on this. Now eNB transmits a Random Access Response which consists of timing increase command, based on that UE adjusts the terminal transmit timing.

The timing boost is initiated from E-UTRAN with MAC message that suggests and adjustment of the timing advance.

3G Interview Questions
Question 21. How Does Lte Ue Positioning Works In E-utran?

Answer :

UE Positioning function is needed to offer the mechanisms to assist or assist the calculation of the geographical position of a UE. UE function knowledge can be used, for instance, in help of Radio Resource Management features, as well as region-based services for operators, subscribers, and 0.33-birthday party service companies.

Question 22. How Many Operators Have Committed For Lte?

Answer :

List of operators devoted for LTE has been compiled by using 3GAmericas from Informa Telecoms & Media and public announcements. It includes a spread of commitment tiers inclusive of intentions to trial, installation, migrate, and many others.

Question 23. What Is Single Radio Voice Call Continuity (srvcc)?

Answer :

Along with LTE creation, 3GPP also standardized Single Radio Voice Call Continuity (SRVCC) in Release 8 specifications to provide seamless continuity whilst an UE handovers from LTE coverage (E-UTRAN) to UMTS/GSM insurance (UTRAN/GERAN). With SRVCC, calls are anchored in IMS network whilst UE is capable of transmitting/receiving on most effective one of those access networks at a given time.

Log Shipping Interview Questions
Question 24. How Does Location Service (lcs) Work In Lte Network?

Answer :

In the LCS architecture, an Evolved SMLC is directly connected to the MME. The goals of this  evolution is to assist vicinity of an IMS emergency call,  keep away from influences to a vicinity consultation because of an inter-eNodeB handover, employ an Evolved  and guide Mobile originated vicinity request (MO-LR) and cell terminated area request MT-LR offerings.

Release nine LCS answer introduces new interfaces inside the EPC:

SLg among the GMLC and the MME
SLs between the E-SMLC and the MME
Diameter-primarily based SLh between the HSS and the HGMLC
Mac OS X Deployment Interview Questions
Question 25. How Does Lawful Interception Works In Lte Evolved Packet System?

Answer :

3GPP Evolved Packet System (EPS) offers IP based  offerings. Hence, EPS is accountable simplest for IP layer interception of Content of Communication (CC) records. In addition to CC information, the Lawful Interception (LI) answer for EPS gives era of Intercept Related Information (IRI) information from respective control plane (signalling) messages as well.

Question 26. What Is Carrier Aggregation In Lte-advanced?

Answer :

To meet LTE-Advanced necessities, help of wider transmission bandwidths is required than the 20 MHz bandwidth specified in 3GPP Release eight/nine. The favored way to that is provider aggregation.

It is of the most wonderful functions of 4G LTE-Advanced. Carrier aggregation lets in growth of effective bandwidth brought to a user terminal through concurrent utilization of radio sources throughout a couple of carriers. Multiple thing carriers are aggregated to shape a larger universal transmission bandwidth.

SIP Interview Questions
Question 27. What Is Relay Node And How Does Relaying Works In Lte-superior?

Answer :

For green heterogeneous community planning, 3GPP LTE-Advanced has brought concept of Relay Nodes (RNs). The Relay Nodes are low electricity eNodeBs that provide better coverage and capability at cell edges.  One of the principle benefits of relaying is to provide prolonged LTE insurance in centered regions at low price.

The Relay Node is hooked up to the Donor eNB (DeNB) thru radio interface, Un, a modified model of E-UTRAN air interface Uu. Donor eNB also srves its very own UE as normal, in addition to sharing its radio assets for Relay Nodes.

UMTS Interview Questions
Question 28. What Are The Measurement Events In Lte?

Answer :

Intra/Inter Frequency Events:

Event A1 (Serving turns into better than threshold) 
Event A2 (Serving becomes worse than threshold) 
Event A3 (Neighbour becomes offset better than PCell) 
Event A4 (Neighbour will become better than threshold) 
Event A5 (PCell turns into worse than threshold1 and neighbour will become higher than threshold2) 
Event A6 (Neighbour will become offset higher than SCell) 
Inter RAT Events:

Event B1 (Inter RAT neighbour turns into better than threshold) 
Event B2 (PCell becomes worse than threshold1 and inter RAT neighbour will become better than threshold2)
Question 29. When Radio Link Failure Is Detected?

Answer :

Radio hyperlink failure to be detected:

upon T310 expiry
upon random access hassle indication from MAC even as neither T300, T301, T304 nor T311 is walking
upon indication from RLC that the maximum range of re-transmissions has been reached
Question 30. What Is Srs Used For?

Answer :

UL reference signal used to degree the channel nice over a section of the bandwidth.

Node B use this information for frequency selective scheduling and hyperlink model selections.

Question 31. What Is Dmrs/drs?

Answer :

DMRS/DRS is uplink reference sign.

Used for :

Channel Estimation and synchronization in UL
EnodeB can use DMRS for calculating TA command for every UE.
    Two Types: 1) PUSCH DMRS.
                      2) PUCCH DMRS.
PUSCH DMRS: 

Included in every resource block allocated to UE for PUSCH transmission.
Distributed best in Frequency domain to hold the PAPR characteristic of SC-FDMA.
12 Resource element in line with aid block allotted to PUSCH DMRS.
PUCCH DMRS: 

Included in every aid block allocated to UE for PUCCH transmission(if transmitted).PUCCH occupies 2 aid block per 1 ms subframe when transmitted.
No of REs used for PUCCH DMRS depends on
a) PUCCH layout to be transmitted and whether
b) ordinary or extended cyclic prefix used.
PUCCH DRMS used greater no of bits in case of format 1,1a,1b and less no of bits in caseof format 2, 2a, 2b.
Question 32. What Is Timing Advance? What Happens If Timing Advance Timer Expires?

Answer :

The timing of UL radio body is relative to DL radio frame. EnB gives timing enhance command to each UE such that each one UL transmissions arrive at the eNodeB in synchronous manner.

If TA timer expires UE goes of reestablishment system or move to idle. 

Question 33. What Is Backoff Indicator? What Is The Use Of Backoff Indicator?

Answer :

Backoff Indicator is a unique MAC subheader that carries the parameter indicating the time put off between a PRACH and the subsequent PRACH.

If the Random Access Response consists of a Backoff Indicator subheader:

set the backoff parameter fee inside the UE as indicated by using the BI area of the Backoff Indicator subheader

else, 

set the backoff parameter price inside the UE to zero ms.

Routing Protcol Interview Questions
Question 34. What Is Bsr?

Answer :

The Buffer Status reporting manner is used to provide the serving eNB with statistics approximately the amount of records to be had for transmission in the UL buffers of the UE.

Question 35. At What Scenario Ue Triggers Bsr?

Answer :

UL information, for a logical channel which belongs to a LCG, will become to be had for transmission in the RLC entity or inside the PDCP entity and either the statistics belongs to a logical channel with higher priority than the priorities of the logical channels which belong to any LCG and for which statistics is already to be had for transmission, or there is no facts to be had for transmission for any of the logical channels which belong to a LCG, in which case the BSR is referred underneath to as "Regular BSR";
UL assets are allocated and wide variety of padding bits is equal to or large than the dimensions of the Buffer Status Report MAC manage detail plus its subheader, wherein case the BSR is referred beneath to as "Padding BSR"
 retxBSR-Timer expires and the UE has statistics to be had for transmission for any of the logical channels which belong to a LCG, wherein case the BSR is referred beneath to as "Regular BSR"
periodicBSR-Timer expires, wherein case the BSR is referred under to as "Periodic BSR".
Question 36. When Different Types Of Bsr Are Triggered?

Answer :

For Regular and Periodic BSR:

if multiple LCG has facts available for transmission inside the TTI where the BSR is transmitted

report Long BSR
 else,
 file Short BSR.

For Padding BSR: if the number of padding bits is equal to or large than the dimensions of the Short BSR plus its subheader however smaller than the size of the Long BSR plus its subheader:

if multiple LCG has information to be had for transmission in the TTI wherein the BSR is transmitted: report Truncated BSR of the LCG with the highest priority logical channel with facts available for transmission;
else 
file Short BSR.

Else if the range of padding bits is equal to or large than the scale of the Long BSR plus its subheader, document Long BSR.

Network Administrator Interview Questions
Question 37. What Is The Content Of Rar?

Answer :

A MAC RAR consists of the four fields 

R
Timing Advance Command
UL Grant
Temporary C-RNTI
Question 38. In What Are The Scenario Ue Triggers Rrc Connection Reestablishment?

Answer :

UE Triggers RRC Connection Reestablishment procedure on following situation: 

Upon detecting Radio Link Failure
Handover Failure
Mobility From E-UTRA Failure 
Integrity Failure Indication Received From Lower Layers
RRC Connection Reconfiguration Failure
Question 39. When Ue Activates Integrity And Ciphering?

Answer :

The SECURITY MODE COMMAND message is used to command the UE for the activation of AS security. E-UTRAN constantly initiates this technique previous to the establishment of Signalling Radio Bearer2 (SRB2) and Data Radio Bearers (DRBs).
AS safety comprises of the integrity safety of RRC signalling (SRBs) in addition to the ciphering of RRC signalling (SRBs) and consumer plane records (DRBs). The integrity protection set of rules is commonplace for signalling radio bearers SRB1 and SRB2. The ciphering set of rules is commonplace for all radio bearers (i.E. SRB1, SRB2 andDRBs). Neither integrity protection nor ciphering applies for SRB0.
The eNodeB sends integrity covered SECURITY MODE COMMAND message to the UE. The UE shall derive KeNB and KRRCint that is associated with integrity safety set of rules indicated in the SECURITY MODE COMMAND. Then, UE verifies the Integrity of the obtained SECURITY MODE COMMAND by way of checking the Message Authentication Code (MAC) inside the SECURITY MODE COMMAND message. If the SECURITY MODE COMMANDmessage fails the integrity safety check, then the UE sends SECURITY MODE FAILURE to the eNodeB.
If the SECURITY MODE COMMAND passes the integrity protection test, then the UE shall derive the encryption keys KRRCenc key and the KUPenc keys associated with the ciphering algorithm indicated in theSECURITY MODE COMMAND.
The UE shall apply integrity protection using the indicated set of rules (EIA) and the integrity key, KRRCintimmediately, i.E. Integrity safety will be applied to all next messages received and sent by the UE, along with the SECURITY MODE COMPLETE message.
 The UE shall practice ciphering the use of the indicated set of rules (EEA), KRRCenc key and the KUPenc key after finishing the manner, i.E. Ciphering shall be implemented to all subsequent messages received and despatched by way of the UE, except for the SECURITY MODE COMPLETE message which is despatched un-ciphered.
Question 40. What Is The Difference Between Lte Fdd And Lte Tdd?

Answer :

The difference lies in the LTE body shape in both the FDD and TDD versions of the LTE. In FDD there can be pair of frequencies assigned within the downlink and uplink guidelines and as a result transmissions from a couple of subscribes can appear on the equal time but on exceptional frequencies as referred to. In TDD, one single frequency can be used at one of a kind time instants by means of multiple subscriber terminals (UEs). Both body versions of LTE can have 1 ms sub-body duration and zero.Five ms slot period.

4G Interview Questions
Question forty one. What Is Resource Block In Lte?

Answer :

LTE body is divided based totally on time slots on time axis and frequency subcarrier on frequency axis. Resource block is the smallest unit of aid allocation in LTE device. It is of approximately zero.5ms length and composed of 12 subcarriers in 1 OFDM symbol. One time slot is identical to 7 OFDM symbols in everyday cyclic prefix and six OFDM symbols in prolonged cyclic prefix. One complete aid block is same to 12 subcarriers by way of 7 symbols in everyday CP. Hence it consists of general eighty four time/frequency factors referred as aid factors in LTE community.

Question 42. What Are The Lte Logical, Transport And Physical Channels?

Answer :

All those channels assist LTE UE establish the reference to the eNodeB, preserve the relationship and terminate the identical. Logical channels are characterised with the aid of the records this is transferred. Transport channels are characterized through how the information are transferred over the radio interface. Physical channel corresponds to a fixed of useful resource elements utilized by the physical layer. Channels are further divided into control channel and site visitors channel at logical channel stage.

3G Interview Questions
Question 43. Explain The Difference Between Reference Signal (rs) And Synchronization Signal (ss) In The Lte? Also Mention Types Of Rs And Ss?

Answer :

Reference signal (RS) is used as pilot subcarrier in LTE much like different broadband wi-fi technology which include WLAN, WIMAX and so on. Synchronization signal is used as preamble series in LTE for synchronization motive. RS is used for channel estimation and monitoring. SS are of two types viz. P-SS and S-SS. P-SS is used for preliminary synchronization. S-SS is used for body boundary determination.

RS are of two sorts viz.

Demodulation RS (DRS)
Sounding RS (SRS).
DRS is used for sync and channel estimation cause. SRS is used for channel great estimation cause. DRS is used in each the uplink and downlink, at the same time as SRS is used handiest in the uplink.

Question forty four. What Is The Function Of Lte Physical Broadcast Channel I.E. Pbch?

Answer :

After preliminary cellular synchronization is completed, UE reads MIB (Master records block) on PBCH (Physical channel). Broadcast channel is referred as BCH at transport level and BCCH at logical degree. MIB composed of downlink channel bandwidth in units of RBs, PHICH period, PHICH aid and gadget frame quantity.

Question forty five. What Is The Advantage Of Using Sc-fdma In The Lte Uplink?

Answer :

The foremost benefit of SC-FDMA is low PAPR compare to OFDMA used in LTE downlink. This increases the efficiency of strength amplifier and as a result will increase the battery existence.

Question forty six. What Is Rssi?

Answer :

RSSI stands for Received Signal Strength Indication. It is used nearly in all of the RATs to identify strength acquired from the cellular in idle in addition to linked/committed modes. This facilitates UE always camped directly to the pleasant cell all of the time. In case of drop in power measured the use of RSSI, both UE or community initiates the handover or cell re-selection is finished.

Question forty seven. Explain Circuit Switch Fall Back I.E. Csfb With Respect To Lte And Gsm?

Answer :

Framework permitting the provisioning of voice offerings through reuse of legacy GSM served CS infrastructure while the UE is served by using E-UTRAN (LTE).To offer voice call aid, Circuit Switch Fall Back is completed to GSM RAT from LTE RAT to facilitate the voice over LTE (VoLTE) characteristic.

Question forty eight. Explain Lte Network Architecture And Various Interfaces?

Answer :

There are numerous entities forming the LTE community structure, the primary interfaces are Uubetween UE and eNB, X2 interface between eNBs and S1 interface among eNB and EPC(Evolved Packet Core).

Question forty nine. Is Lte A 4g Protocol?

Answer :

The networking industry acknowledges LTE a 4G era together with WiMax and HSPA+. None of these certified as 4G based at the original definition of the International Telecommunications Union (ITU) standards group, but in December 2010 the ITU redefined 4G to encompass them.

While a few advertising and marketing specialists and press have labeled LTE-Advanced as 5G, no broadly-authorized definition of 5G exists to justify the claim.

Question 50. What Is The Difference Between Lte And Lte Advanced?

Answer :

LTE is specified in 3GPP launch eight and release nine. LTE advanced is laid out in 3GPP launch 10. The principal difference among them is provider aggregation is brought in LTE superior. Number of antennas supported by way of MIMO has been expanded to 8 in LTE superior.