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VoLTE Call's

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In normal LTE networks, the users are sent to legacy CS networks (2G/3G) via CSFB mechanism whenever they have to make a voice call. CSFB is a good solution and it has evolved alot but still it takes longer time. The alternate solution is to have the voice session over LTE which is known as VoLTE (Voice over LTE). A VoLTE call is much quicker to setup as there is no fall back required to another RAT and also it has a better quality due to more bandwidth and advanced features.  However, VoLTE is basically a PS call and it has its own challenges. VoLTE Call Setup Success Rate, Call Drop Rate and Quality are major issues that operators face after enabling VoLTE. In this article, I will explain the VoLTE basics along with capacity planning and dimensioning VoLTE Call Setup Traditionally, a VoLTE user attachs to the LTE network using both QCI-9 and QCI-5. QCI-9 is the default bearer for data while QCI-5 acts as the default bearer for voice and it carries SIP signaling. When a call n
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LTE Measurements Understanding

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There are several IEs to configure measurement control in detail, which are under measConfig IE in RRC Connection Reconfiguration message. They are not clearly described with specific picture but here is what I understand. Form the top picture, we might think of an ideal case as (neighbour) cell measured value in yellow goes up linearly. Threshold is bottom line and offset (including several kinds of sub-offset values though) and hysteresis can be applied. Entering condition in this case would mean yellow line cross over threshold (+hysteresis) with blue "x" mark. From this point, timeToTrigger and reportInterval can be applied through the blue block. Leaving condition in this case could not be applied because it never get down go threshold (-hysteresis) as grey "x" mark. If measConfig needs to be removed, it can be managed by RRC Connection Reconfiguration procedure. From the bottom one, we can think of entering and leaving condition with blue "x
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System Information in LTE :- MIB & SIB

System Information (36.331 Rel 13 Mar 2016) SIB Description Comment MIB Downlink channel bandwidth, PHICH config SFN 1 PLMN, TAC, Cell Id, access restrictions, q-RxLevMin, frequency band, MFBI Scheduling of other SIBs 1 BR Bandwidth Reduced, limited channel bandwidth of 6 PRBs eMTC (enhanced Machine Type Communications) 2 Common radio resource config, access class barring, MBSFN config UL frequency and bandwidth 3 Cell re-selection common information 4 Cell re-selection information for intra-frequency neighbouring cells Black cell list 5 Cell re-selection information for inter-frequency neighbouring cells 6 Cell re-selection information for UTRA 7 Cell re-selection information for GERAN 8 Cell re-selection information for CDMA2000 9 Home eNodeB name 10 ETWS (Earthquake and Tsunami Warning System) Primary notification 11 ETWS Secondary notification 12 CMAS (Commercial Mobile Alert Service) notification 13 MBMS control information associated with one or more MBSFN
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E-UTRAN

S-GW The Serving Gateway (S-GW) provides user plane connectivity, the UE being on one side, and the Packet Data Network Gateway (P-GW) on the other side of the physical S-GW element. Depending on the network provider’s approach, these elements can be separate, or they can be combined physically as a single element. It should be noted that no control messaging goes between the UE and the S-GW, as the control plane is taken care of by the MME element. The S-GW element takes care of the following functionalities: . S-GW is the local anchor point for the inter-eNB handover procedure; . S-GW is also an anchor point for the inter-3GPP network mobility; . Lawful Interception (LI); . packet routing and forwarding; . S-GW handles packet buffering in the E-UTRAN idle mode; . S-GW handles the network initiated/triggered service request procedure; . packet marking at the transport level for both DL and UL; . Charging Data Record (CDR) collection, which can identify the UE, PDN an
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Home eNB

It is possible to use an additional element set, which is called Home eNB and  Home eNB  Gateway. Specific aspects for the Home eNB, that is, HeNB, are the following: . HeNB are equipment that can be utilized in the customer’s premises and that uses the  licensed operator’s spectrum; . HeNB is meant for the enhancing of the network coverage and/or capacity; . includes all the eNB functionalities, added by the HeNB-specific functions that are related to  the configuration and security. The Home eNB Gateway (HeNB GW), which is related to the HeNB, solves the problem of  support for a possibly very large number of S1 interfaces. It is thus an additional element that  can be used for the balancing of the interfaces. Furthermore, the HeNB concept can be utilized in the following access scenarios: . in the closed access mode, only predefined Closed Subscriber Group (CSG) members can  access the respective HeNB; . in the hybrid access mode, both the members and nonme
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eNB Functionalities

eNodeB The eNB element of LTE is responsible for radio transmission and reception with UE. eNB  provides the required functionality for the radio resource management (RRM), including  admission control, radio bearer control, scheduling of user data, and control signaling over  the air interface. In addition, eNB takes care of the ciphering and header compression over the  air interface. The clearest difference between UTRAN and E-UTRAN can be seen in the role of the base  station. The eNodeB of LTE now includes basically all the functionalities that were previously  concentrated on the RNC of the UTRANsystem. In addition, the traditional tasks of the NodeB  are still included in the new eNodeB ( eNB ) element. eNB works thus as the counterpart of the  UE in the radio interface but includes procedures for decision making related to the connections. This solution results in the term “flat architecture” of LTE, meaning that there are less  interfaces and only one element in
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