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SRB1 and SRB2

NAS messages are transmitted over SRB1 till SRB2 is established. In other words: SRB1 is also used to encapsulate the NAS message if SRB2 has not been configured. As per the standard statement "SRB1 is for RRC messages (which may include piggybacked NAS messages) as well as for NAS messages prior to the establishment of SRB2. All of them use DCCH logical channel." http://sharetechnote.com/html/5G/5G_SRB.html  One more thing to remember is that SRB2 is used when the security procedure is complete. SRB2 has a lower priority than SRB1 and it is always configured after the security activation. From RLC point of view: SRB0 uses the transparent mode (TM) RLC, while SRB1 and SRB2 use the acknowledged mode (AM) RLC.  
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TDD Duct Phenomena Interference

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Atmospheric ducting mode -- the waves are bent by the atmospheric refraction as shown below: Using this model, the downlink signal of the interferer eNB can travel for hundreds of Km which will result in an additional time offset when arriving at the interfered area, this delayed DL signal will impact the uplink signal of the TDD subframe (it will be considered as interference compared to our useful UL signal). In the case of coastal areas, the impact of phenomena will increase with the increase of the temperature (Evaporation of seawater increase => hydrometer scatter). You can expect to experience regularly this kind of degradation during Spring and Summer until the temperature will decrease (starting from Autumn).
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UE switch off versus Airplane mode

UE Switch OFF versus Airplane mode. Both of them work the same. After both processes, the UE context will be released from gNB. They will again do RACH and all those processes to get notified to network.  In Wireshark, you can see this as detaching request. 
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