Category: Uncategorized

  • 4G LTE Interview Questions 1

    Q. What is Difference between MIB and SIB? MIB and SIB are two types of System Information (SI) that is broadcasted in the serving are of particular cell. SI is carried by the logical channel BCCH, which in turn is carried by either of the transport channels BCH or DL-SCH.Master information Block (MIB): is a […]

  • Question: Is there Tracking Area Update (TAU) procedure in 5G like we see in 2G, 3G and 4G?

    Answer: In 5G we have Registration Area Update (RAU) instead of Tracking area Update (TAU). A Registration area is a list of tracking areas that are assigned to UE by 5G Network. This is especially useful in the high mobility scenarios where assigning a tracking area list (Registration Area) to UE reduces the signalling on […]



    3GPP defines the overall 5G security architecture, illustrated in Figure above. This includes many network architectural elements and concepts such as: Network access security (I) which is the set of security features that enables user equipment (UE) to authenticate and access services via the network securely, including 3GPP access and non3GPP access, and particularly to […]

  • What is the difference between CU and DU in 5G?

    In 5G the basestation is called as the gNB. According to the 3GPP recommendation TR 38.801, the gNB is further subdivided into the Centralized Unit (CU) and Distributed Unit (DU) as shown in the diagram below. The Centralized Unit is used to support higher layer protocols like SDAP, PDCP, and RCC. While the lower layer […]

  • Enhanced Common Public Radio Interface (eCPRI)

    Background Although Common Public Radio Interface (CPRI) has been the main Fronthaul interface standard, many operators started to question its suitability to high bandwidth 5G use cases. Improvements to efficiency and link capacity utilization were requested. Also advanced networking and OAM features of mainstream packet transport standards were requested. What is CPRI? A digital public […]

  • 8T8R Antenna Beamforming Technology Introduction

    Principles of 8T8R Beamforming Beamforming is a digital signal processing technology that can be implemented on adaptive 8T8R array antennas. Baseband weighting of multiple antennas transmitting signals is used to form high-gain, narrow beams. These beams target user devices, improving signal strength and reducing interference, as shown in the figure 1 below. 8T8R Antenna Introduction […]

  • IMS Procedures Tutorial

    Any discussion of IMS protocols must start with a dialogue describing the procedures being implemented. It is important to note that there is no “one size fits all” procedural flow; IMS in LTE offers a lot of flexibility to both network equipment manufacturers and network operators. Note that the processes described here are strictly from […]

  • 1. IMS Procedure: Public Data Network (PDN) connectivity

    As in legacy 3GPP technologies, the UE starts connection by issuing a Radio Resource Control (RRC) Connection Request. Note that while either the UE or the network can trigger the connection request, it is always initiatedby the UE. This request includes both the UE identity information and the call establishment cause (i.e.Mobile Originating Signaling or […]

  • 2. IMS Procedure: Authentication

    Now that NAS signaling is established, the network initiates an Authentication Request or challenge. Once the UE’s Authentication Response is deemed valid, the network sends a NAS Security Mode Command. Note that while neither the Authentication Request nor the Authentication Response is integrity-protected, the Security Mode Command is protected. The UE then sends a Security […]

  • 3. IMS Procedure: Bearer Setup and EPS Attach

    At this point, additional radio bearers must be set up. The network sends an RRC Connection Reconfiguration to activate the EPS bearer. The UE confirms successful completion with an RRC Connection ReconfigurationComplete message and then finalizes the Attach procedure and accepts the activation of the EPS bearer.It should be noted that the way a default […]