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    Showing posts with label LTE. Show all posts

    LTE FUNDAMENTALS

    Jitendra Kumar

    basic LTE Fundamental for beginners

    LTE ARCHITECTURE

    Joni Tyagi

    LTE (LONG TERM EVOLUTION) ARCHITECTURE


    HISTORY

    • Two Systems that impacted almost every Human Life
    • (i)   Mobile Communication Via 2G Networks.
    • (ii)  Wired & Wireless Data Connectivity via xDSL & WLAN 802.11 a/b/g standards.
    • 3G Networks is the first major step towards the convergence of both these technologies
    THE WAY TO LTE-3G LIMITATIONS
         The ‘Maximum Bit Rates’ are still in the range of 20mbps
         This is way behind the other popular wireless technologies like
         WiFi: 802.11 a/b/g/n
         WiMax: 802.16 e/m
         The ‘Latency’ of User Plane Traffic (UMTS > 30ms) and Resource
         Management Procedures (UMTS > 100ms) is still too high
         The ‘Terminal Complexity’ of WCDMA systems is quite high, and resulting
    (i)                  Expensive Equipment
    (ii)                 Poor Performance
    LTE GOALS
         The ‘Terminal Complexity’ of WCDMA systems is quite high, and resulting
         It shall Compete especially with 802.16e/m in data rates
         It must retain the high mobility features of GSM/UMTS
    LTE SAE DIAGRAM AND FEATURES
    LTE-ARCHITECTURE

    LTE SAE DIAGRAM

    LTE FEATURES:

    ·         Simplify the RAN: Reduced the number of RAN Nodes and Interfaces.
    ·         Reduce Latency.
    ·         Increase Throughput and Improve Spectrum Efficiency.
    ·         Flexibility in using Frequency Bands.
    ·         Migrate to Optimized PS Domain with no CS Domain.
    ·         Flat Architecture: Minimize the risk of single point of failures in the network.
    ·         Efficient Inter-working between 3G and Non-3G specified systems.
    ·         Improve Terminal Power Efficiency.
    ·         All IP Transport Network.
    WIRELESS TECHNOLOGY COMPARISON
    WIRELESS-TECHNOLOGY-COMPARISON

    LTE /SAE INTERFACE ARCHITECTURE
    LTE /SAE-INTERFACE-ARCHITECTURE

    NETWORK ELEMENT FUNCTIONS

    eNODE B Functons:

    ·         Only Network Element in EUTRAN.
    ·         eNB Can Handle Several Cells.
    ·         Radio Admission Control & Radio Resource Management(RRM) Dynamic   Resource Allocation(Scheduler).
    ·         Radio Bearer Mgmt: Setup, Modification and Release.
    ·         UE Connection State Management and UE-MME Connection MME Selection at   the Attach of the UE.
    ·         Measurements Collection and Evaluation.
    ·         Handover Decisions and Triggering. eNB-eNB Connections to Handle HO   Ciphering and Integrity Protection.
    ·         IP Header Compression and Decompression User Data Routing between UE and   SAE-GW System Information Broadcasting.
    ·         Transmission of Paging Messages to UEs.

    MME Functons:

    ·         Pure Signalling Entity in EPC. Contains VLR Functionality with-in!
    ·         Subscriber Attach/Detach: Non-Access Signalling (NAS).
    ·         Idle State Mobility Handling: Tracking Area Updates.
    ·         MME-MME Connections to Handle Handovers & TAUs.
    ·         Signalling Co-Ordination For SAE Bearer Setup & Modification & Release.
    ·         Security (Authentication, Ciphering, Integrity Protection.
    ·         Trigger and Distribution of Paging Messages to Enb.
    ·         Roaming Control with the Connection to HSS.
    ·         A UE can use the Services of only one MME At Any Given Time!

    HSS Functons:

    ·         Permanent and Central subscriber Database.
    ·         Stores Mobility and Service Data For Each Subscriber.
    ·         Contains Authentication Centre Functionality also.

    EIR Functons:

    ·         IMEI Validation.
    ·         MME Interacts with EIR to Validate the IMEI of a UE.
    ·         Maintains White, Grey, and Black Lists of IMEIs.

    PCRF Functons:

    ·         QoS Handling Function
    ·         QoS Policy Negotiation with PDN
    ·         Validates the QoS of EPS Bearers Requested by EPC As well
    ·         Charging Policy: Determines how the Packets should be Accounted
    ·         PCRF to Provide Policy and Charging Rules Every time a Bearer is Se!

    SGW Functons:

    ·         Packet Data Anchoring Function With in EPC.
    ·         Receives UL Data From eNB/SGSN and Transmits to PGW.
    ·         Receives DL Data From PGW and Transmits to eNB/SGSN.
    ·         local Mobility Anchor point for inter-eNodeB handover.
    ·         Mobility anchoring for inter-3GPP mobility.
    ·         “End Marker" Notification to Source eNB or SGSN after Path Switch.
    ·         Downlink Packet Buffering and Initiation of Network Triggered Service.
    ·         Packet Marking W.R.T QOS Implementation Required for a EPS Bearer.
    ·         Bearer Binding Functions.
    ·         A UE can use the Services of only one SGW At Any Given Time!

    PGW Functons:

    ·         Packet Data Anchoring Function With in EPC
    ·         Receives UL Data From SGW And Transmits to PDN
    ·         Receives DL Data From PDN and Transmits to SGW
    ·         Mobility Anchor point for Non-3GPP Mobility
    ·         DHCP Function: IP Address Allocation TO UE
    ·         Deal with PCRF for Finalizing PCC Rule for a EPS Bearer
    ·         Packet Marking W.R.T QOS Implementation Required for a EPS Bearer
    ·         Policy and Charging Enforcement Function [PCEF]: Billing Generation
    ·         Bearer Binding Functions
    ·         UE Can use Services of Many PDN GWs to Connect to Multiple PDNs

    LTE UE Power on Interview Questions Answer

    Joni Tyagi
    LTE-UE-Power-on-Interview-Questions-Answer

    Q01. In power on which Layer activate 1st ?
    Q02. What is the 1st job RRC Layer performed during power on procedure?
    Q03. How Physical Layer Scan all Frequencies and pick-up 1 frequency?
    Q04. How UE select a Frequency?
    Q05. What is cell selection and re-selection procedure in lte?
    Q06. How UE guess middle DC frequency of a Bandwidth?
    Q07. How NAS layer select PLMN if no’s of PLMN information provided by RRC Layer?
    Q08. What is PSS, which sequence is using in PSS?
    Q09. What kind of information PSS Carry?
    Q10. What is the location of PSS in Type-1 Frame structure?
    Q11. What is the location of PSS in Type-2 Frame structure?
    Q12. What is SSS, which sequence is using in SSS?
    Q13. What kind of information SSS Carry?
    Q14. What is the location of SSS in Type-1 Frame structure?
    Q15. What is the location of SSS in Type-2 Frame structure?
    Q16. How UE calculate PCI?
    Q17. After Calculate PCI how UE validate PCI, is it correct or not?
    Q18. What is the role of System Information’s in Power on procedure?
    Q19. What is the difference between MIB and SIB in LTE?
    Q20. What is P-compensation in cell selection procedure?
    Q21. What is p-max in p-compensation?
    Q22. What do you mean by cell priority in lte?
    Q23. How many types of Priority available in lte?
    Q24. What is Suitable Cell and Acceptable Cell what is the difference between them?
    Q25. What is Barred Cell and Blacklisted Cell and difference between them?
    Q26. What are Access Class (AC), How many AC are available in lte?
    Q27. From where UE get Barring information?
    Q28. What do you mean by Barring Factor, Barring Step, and Barring Time?
    Q29. What are the durations of above Barring Information Elements have?
    Q30. What kind of Information is carryin MIB==>PHICH?