5G NBIOT LTE Question Answers

Home                 LTE                NB-IoT            5G(NR-NSA)   Hi guys, this is our first 5G basic part in which we touch upon the difference between gNB and ng-eNB and service based architecture. What is gNB? It is the node that provides NR C ontrol Plane and  U ser Plane protocol terminations towards the UE. gNB is connected to the 5G Core Network through the NG Interface. What is ng-eNB? It is the node which provides E-UTRA/LTE C ontrol Plane and  U ser Plane protocol terminations towards the UE. ng-eNB is connected to the 5G Core Network through the NG Interface. What is NG-RAN Architecture? NG-RAN is the representation of the newly defined Radio Access Network(RAN) for 5G. It allows the UE(device) to get both NR and LTE radio access. The below diagram shows the inter-relation of NG-RAN with the overall  5G Core Network system. Xn interface: An ng-eNB is connected with other ng-eNBs and gNBs through the Xn interface. NG int

Home                 LTE                NB-IoT            5G(NR-NSA)   What is PSM in NB-IOT? It is a mode through which the UE notifies the network of its indefinite dormant state. Power Saving Mode (PSM) was introduced in 3GPP Release 12 24.301-5.3.11, to improve battery life of IOT devices. PSM is similar to power-off, with the exception that the UE remains registered with the network and there is no need to re-attach or re-establish the PDN connection. Is UE(device) reachable in PSM? UE is unreachable in PSM for mobile  terminating services. UE(device) is reachable for mobile terminating services only for the period of an Active Time after a mobile originated event like data transfer or signaling.  E.g. After a periodic TAU/RAU procedure. Does PSM support CS domain? / Limitations of PSM. CS domain is not supported on the network side by PSM UE. PSM should only be used by UEs using the PS domain, SMS and

Home                 LTE                NB-IoT            5G(NR-NSA)   What is MAC-ContentionResolutionTimer? The timer which states the number of consecutive subframe/ subframe s during which MAC entity will monitor the PDCCH after the Msg3 is transmitted. (3GPP TS 36.321 version 13.3.0 Release 13)  The UE will start mac-Contention resolution timer from the immediate subframe after transmitting Msg3.  As UE is waiting for the contention resolution which is through PDCCH reception on C-RNTI (in connected mode), the UE should be monitoring PDCCH. So that the time duration in which mac-Contention resolution timer is running, is also considered as Active Time. Which timer is started after msg3 is transmitted? Following two timers are started Once,  msg3 is transmitted: 1. T300 : Transmission of RRCconnectionRequest 2. Contention Resolution Timer: broadcasted in SIB2. If the UE doesn't receive msg4 (Contention Resolution message) within