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    Showing posts with label Samsung Interview Question Answer. Show all posts

    Samsung Interview Question Answer

    Joni Tyagi
    Samsung Interview Question Answer
    Q1. In EPC which node you comfortable?
    Q2. Initial attach architecture?
    Q3. Where GUTI allocates?
    Q4. How MME know to send initial attach request particular S-Gw (out of 5-6 S-Gw present)?
    Q5. How enb know to send initial attach request to particular MME (out of 5-6 MME present)?
    Q6. RRC connection sent which channel?
    Q7. What's IE present in create session request?
    Q8. Types of handover in LTE?
    Q9. About PCRF and its interface?
    Q10. SIB information SIB1 to SIB8?
    Q11. When S5 and S8 interface use?
    Q12. Soft Handover and Hard Handover?
    Q13. If UE has 16 Bearer than how much E-RAB will be established for a UE?
    Q14. How many Bearers would be establishing between Single UE to Single PDN?
    Q15. Can we use 2 Application via using 1 dedicated bearer or we have to require 2 bearers separately?

    Ericsson Interview Question Answer

    Joni Tyagi
    Ericsson Interview Question Answer
    Q1. In what procedure you are comfortable.
    Q2. You knew end to end call flows? Other node also?
    Q3. What is your idea on handover and tau?
    Q4. Which is the fastest handover?
    Q5. Is there any possibility to change the gateway in HO?
    Q6. UE having 3 bearers so in that one bearer is failing in handover than in situation what you will calling that handover success or failure?
    Q7. in which message ue receive ip address?
    Q8. How many eps bearer ue can have Actually?
    Q9. What is Data bearers?
    Q10. What is the maximum limit of E-RAB bearer?
    Q11. How the pdn is getting connected using what basis and which parameters?
    Q12. So who will be starting the dedicated bearer?
    Q13. What are the role of HSS in the network?
    Q14. Did you mean dedicated bearer is also try to create?
    Q15. How PDN is selected see in the network there can be 10 pdn so ue 1 can connect to pdn2, ue 2 connect to pdn5. That can be mix and match it can connect any pdn so by using what parameter pdn is selected?
    Q16. Why we require 4G?
    Q17. Difference between 3G and 4G with technical answer?
    Q18. Describe the LTE Architecture in details?
    Q19. See in network there can be many S-GW than which S-GW will be selected?
    Q20. Using the DNS what is the possibility select S-GW, means what it will check from DNS?
    Q21. Where is the role of DNS server, role in the select in the S-GW?
    Q22. HSS and DNS are same one?
    Q23. How the latency will reduced in 4g by using what?
    Q24. 3G user can access 4g network?
    Q25. 4G user can access 3g network?
    Q26. How call facility supported in lte?
    Q27. So initial ue message what are the nas message possible in initial ue message?
    Q28. Piggybacked message in initial ue message what is that?
    Q29. Similar to attach request is their any other message in initial ue (service req) (tau req)?
    Q30. Attach req contents?
    Q31. Attach type available?
    Q32. Esm message container in attach request?
    Q33. In initial request ue that is the first message than how guti allocation is possible?
    Q34. Why guti is being used?
    Q35. What is the possibility of guti and why its coming as a new identity in picture?
    Q36. What is the main ie in initial ue message without it there is no used for this message?
    Q37. How network will differentiate between home and roaming subscriber?
    Q38. What is that plmn id?
    Q39. After finding that this ue is a roaming subscriber than what network will do?
    Q40. Do you have any TTCN3 experience also?
    Q41. How you debug attach reject log so you have got a log and the log you can see fetch and the getting attach reject what are the scenario of attach reject?
    Q42. Have you heard for T-3412? And why is this is?
    Q43. Why ue has to send TAU with timer?
    Q44. Is it happened in idle and connected both?
    Q45. When paging will happened you are getting the DL data than what are the scenario of paging?
    Q46. Whenever you received a call than paging will happen with respect to ue? Either ue in idle or connected?
    Q47. Tell me something you known in TTCN3?
    Q48. What are your experience in python and main use of python?
    Q49. How you can say this is flexible?
    Q50. Weather it is a low level or high and medium level language?
    Q51. Can you tell something about memory in python?
    Q52. Stack and heap memory difference?
    Q53. So how it will used in programming memory?
    Q54. Can you tell about data types in python?
    Q55. Mutable or immutable?
    Q56. Day to day scenario what we will use mutable or immutable?
    Q57. In python can you assign any negative number?
    Q58. What are the different phases of testing you are worked on?
    Q59. Have you work on preparing a test case?
    Q60. So can you tell me the life cycle of defect? What kind of activity you will do till close that bug?
    Q61. Do you have any question for me?

    Anritsu Interview Question Answer

    Joni Tyagi
    Anritsu Interview Question Answer
    Q1. How you work on TTCN3?
    Q2. Tell us about handover procedure of X2?
    Q3. What happen when target enb get down and serving enb send an handover request toward target enb?
    Q4. IE used at the time of rrc reconfiguration initiate mobility of handover?
    Q5. Soft handover and Hard handover?
    Q6. What happens when after receiving the measurement report from ue serving enb want to established the connection but target enb suddenly down?
    Q7. After getting the reconfiguration message on phy on ue than it passing through the MAC RLC PDCP layer till RRC so what they do?
    Q8. How ue knows that this is a rrc reconfiguration message (crnti) ?
    Q9. RLC modes and there difference?
    Q10. Type of DCI and there used?
    Q11. SR and BSR difference and who initiate it?
    Q12. Type of BSR?
    Q13. Type of mac ul and dl control element?
    Q14. Difference between harq and arq?
    Q15. Different type of harq?
    Q16. How ue or enb know that what is the harq process number?
    Q17. What is meant by logical channel id and group?
    Q18. What is cqi and there range and who sent it?
    Q19. Is each cqi values is directly connect to mcs? Or what is the scenario, range of mcs?
    Q20. What is ca? Do you experience about log related in ca?
    Q21. What is PHR?
    Q22. What is timing advance and why it is used in mac dl ce?
    Q23. Different type of SRBs and DRBs and when which SRB is used?
    Q24. What message are sending on SRB0,1,2?
    Q25. Rrc establishment message sent by ue on which srb?
    Q26. Rrc reconfig message sent by network on which srb?
    Q27. Tell me rach procedure?
    Q28. How the preamble info will selecting by ue like which preamble we should use?
    Q29. What mobility control info and each config dedicated in rrc reconfiguration ie?
    Q30. After receiving rar from enb ue send message 3 than how ue get grant of ul?
    Q31. At the time of receiving rrc connection setup how ue knows that its his rrc connection setup?
    Q32. Where the ul resource grant for sending rrc connection setup complete?
    Q33. If we received sib and rrc setup at same time than how ue recognize which time it decode rrc message and sib?
    Q34. Which channel used for sending sr and bsr?
    Q35. How much process used in fdd?
    Q36. What is the message send on srb2?
    Q37. What is criteria used to follow for crate srb2?
    Q38. What is meant by authentication req used in attach procedure?
    Q39. Did security is enabled before sending authentication req?
    Q40. What is the first message on srb2 between ue and enb that ue send?
    Q41. What is the requirement of security enabled 2 times in attach procedure?
    Q42. When mme send security mode command and what is the info present in it?
    Q43. So in the security mode command there is direct transfer of key to ue mme or something different procedure?
    Q44. Failure cases of rrc reconfiguration?
    Q45. After receiving rrc connection setup than ue need to send rrc connection setup complete message so need ul resource where that resource comes from?
    Q46. After receiving rrc reconfiguration message from PHY to MAC and MAC to RLC than what is the first work that done by RLC and using what mode of operation?
    Q47. Security in attach procedure come to deal by which layer?
    Q48. Can you tell me what is pics and pixit in TTCN3?
    Q49. What is use and how to use TTCN3 as for scripting?
    Q50. What is used of python scripting?
    Q51. Difference between set, list and tuple in python?
    Q52. How to write dictionary program?
    Q53. How to check the message if rrc reconfiguration message is miss than how you know that what is bug because you can’t even show the rrc message than how you find it?
    Q54. What you used in python scripting if rrc configuration message bug found?

    Altron and Aricent Interview Question Answer

    Joni Tyagi

    Altron and Aricent Interview Question Answer
    Q.1. What are the KPIs for testing the performance and quality of LTE networks?

    Ans. Validating the performance and quality of an LTE network requires a high rate and varied mix of data traffic to judge the end-user experience. Traffic mix can be based on the type of subscribers, applications/services used, usage, etc. Some of the key KPIs which need to be validated are:
    • Latency and packet loss
    • Jitter
    • Throughput
    • Perceptual video and voice quality
    Number of active sessions, users, and transactions per second

    Q.2. What are the challenges in testing IPv6 in an LTE network?

    Ans. Although IPv6 is mandated in LTE, as of now, most of the existing networks and their components use IPv4. As a result, we have nodes with support for both IPv4 and IPv6 stacks in the network. The integration testing of IPv4/IPv6 poses a big challenge because all network services will need to be tested for interoperability without any issues between IPv4 and IPv6. Added to this, some tunneling schemes from IPv6 to IPv4 are another area of focus.

    Q.3. What are the key attributes to focus on during testing, to minimize the issues with LTE EPC nodes after deployment?

    Ans. Few of the key attributes to focus on for better solution reliability are:

    The LTE EPC node should be validated with an optimized set of invalid scenarios. Prior experience in interop and field testing is a definite help for identifying such scenarios.
    While testing for the scalability and benchmarking, next to real-time scenarios should be simulated, such as a different mix of traffic, simultaneous calls, new calls per second, etc).
    Inter-RAT handover or inter-working with non-3GPP must be tested based on the existing coverage in the deployment area Redundancy and resiliency should be given more focus during testing from a deployment perspective.

    Q.4. There are diameter based interfaces in earlier technologies. How is testing for those different from LTE EPC testing?

    Ans. There are around 12-14 diameter based interfaces in LTE. There are many new interfaces like SWx, STa, and SWa that have been introduced to support non-3GPP interworking. At the same time, there are certain interfaces like Gx, Rx, and Sh which also exist in IMS for interfacing with the PCRF. But in the LTE context, there is a multitude of additional AVPs that require the test tools to be upgraded and complicate testing. The test scenarios are quite different in terms of message flow, handling, and parameter validation.

    Q.5. Do you recommend that conformance testing as per the specs by GCF/MSF is enough for an LTE node?

    Ans. No, it is not enough. Conforming as per these specifications is necessary but not sufficient. It is advisable to conform to these specs as they are standardized and different stakeholders expect nodes to comply with these. But at the same time, based on our experience, the node should also be tested against many field-like complex scenarios, optimized negative scenarios, and interop testing scenarios.

    Q.6. What are the challenges in identifying the right traffic mix for load testing?

    Ans. The traffic mix for LTE testing needs to consider different signaling events as well as data formats.

    There are multiple interfaces that can initiate signaling messages with the EPC. Testing for these requires synchronization of triggering the messages from these interfaces. There are different frequencies for each kind of message and the number of such triggers for an attached UE is also different for different events. The messages also depend on the number of subscribers normally active at any moment and signaling events differ for different numbers and kinds of subscribers.

    The area where the EPC is going to serve also results in different kinds of traffic. In an urban area, there would be a high rate of handovers, but in rural areas, the rate of handovers may be less. In an enterprise deployment, the number of active users may be more than in a consumer market, and so on.

    The data formats also differ a lot based on the usage of different applications. Video download may result in large packets and high data throughput, but email usage may result in larger active duration, but smaller packet sizes.

    Identifying the different use cases and traffic mixes for different deployment thus become a challenge.

    Q.7. Can you give some examples of applications that would use dedicated bearers? Do these applications typically use network-initiated dedicated bearers or user-initiated?

    Ans. Some examples of using dedicated bearers can be found in voice and video traffic. Applications like IPTV and video on demand, which require guaranteed bandwidth, may also require dedicated bearers. The dedicated bearers can be user-initiated or network-initiated. Mostly for voice and video applications the network would initiate dedicated bearers based on the SDP exchanged for the media for IMS calls. For applications like IPTV and video on demand, it could be either UE or network-initiated.

    Q.8. Can you share some of the important metrics collected for a high available EPC solution in carrier-grade networks?

    Ans. The important metrics for carrier-grade EPC solutions validate the level of reliability and switchover time. Switchover could happen for both the control and the data plane. These important metrics are:
    • Switchover time for control plane
    • Switchover time for data plane
    • Amount of memory for buffered packets during switchover
    • Transmission time for buffered packets
    • Level of reliability
    • Check all levels of redundancy for all resources, interfaces, and software solutions
    • Signaling and data throughput after switchover

    Q.9. Is there a way to monitor the UE messages from a simulated eNodeB?

    Ans. Yes. Although the UE messages are encrypted, with a simulated eNodeB it is possible to collect the UE keys from the eNodeB simulator and UE exchanges. Alternatively one can use pre-shared information. The eNodeB simulator can also decipher the NAS messages exchanged between the UE and the EPC.

    Q.10. How is the voice quality measured in EPC testing and what aspects are covered as part of voice testing through EPC?

    Ans. Voice quality is measured using multiple voice test tools to test the following:
    • Jitter
    • Latency
    • Voice quality
    • Echo cancellation
    • Comfort noise generation
    • Voice break at handovers

    Q.11. What are the essential scenarios which must be tested for an MME?

    Ans. Following are the necessary scenarios which need to be tested for an MME:
    • Default bearer creation/deletion/modification
    • Dedicated bearer creation/deletion/modification
    • Network initiated triggers (default/dedicated bearers)
    • Handover (S1, X2)
    • TA updates
    • Release/Idle mode
    • Paging
    • ISR

    Q.12. What is a major challenge in testing IoT for voice scenarios like CS fall back?

    Ans. For voice testing, all the different scenarios like CS fallback, IMS calls, SRVCC, etc. have to be tested. The different voice application nodes like the IMS network, CS network of 3G network, SRVCC handling IMS application server, and SCP nodes have to be simulated such that they can receive and initiate triggers.

    The nodes need to be tested for different user capacities and different kinds of voice applications, like emergency calls, voice and video calls, multiband audio; and require multimedia application support in the simulators. This poses a major challenge.

    Q.13. How it is ensured that voice and data go on simultaneously; is it possible on CS fall back?

    Ans. Voice and data can go on simultaneously in CS fallback, depending on the network and UE capability. If the PS session is going on in LTE and voice is transferred to 3G, then the UE needs to support two kinds of radio at the same time. This may or may not be possible depending on the UE’s capability. Even in the case where both PS and CS are handed over to 3G, depending on the UE’s and the network’s capability, either the PS session may be suspended when the CS session is ongoing or both PS and CS sessions may go on simultaneously.

    Q.14. What are the best commercially available test tools for EPC core interoperability, inter-RAT, or non-3GPP testing?

    Ans. Normally for interop, customers prefer to test with a real node from another vendor, rather than using commercially available test tools.
    Altran has frameworks for different LTE EPC core elements (i.e. MME, SGW, PGW, HSS, and PCRF) and eNodeB. We have used these for interop for some of our customers.

    Additionally, IxCatapult M500, NetHawk EAST EPC, Polaris LTE Functional Test Tool, Spirent Landslide, and Spirent Test Centre are some of the other tools used for EPC node testing. 

    The selection of the tool depends on different aspects like the node to be simulated, testing phase to be simulated for, the scope of testing, cost of the tool, etc.

    Q.15. Are there any end-end network monitoring solutions you would recommend? Which vendors?

    Ans. From the monitoring or protocol analyzer perspective many tools are there which focus mainly on the access network side. For example Anritsu, R&S, Tektronix, and Aeroflex.

    From an end-to-end perspective, the few vendors that can be considered for network monitoring solutions are JDSU and Tektronix. Often, Wireshark or other tools used for testing can fulfill these requirements.