Use of X2 Interface in LTE

Question

Want to know advantage and use of X2 Interface in LTE, please describe in detail.

Answer 1

The list of functions on the X2 interface is the following:

1. IntraLTE-Access-System Mobility Support for UE in LTE_ACTIVE:

   • Context transfer from source eNB to target eNB;
   • Control of user plane tunnels between source eNB and target eNB;
   • Handover cancellation.

2. Load Management

3. Inter-cell Interference Coordination:: This function allows keeping inter-cell interference under control. For this neighbouring eNBs exchange appropriate information allowing that eNBs make radio resource assignments such that interference is mitigated.

4. Uplink Interference Load Management::This function allows indicating an uplink interference overload and resource blocks especially sensitive to inter-cell interference between neighbouring eNBs, such that neighbour eNBs can co-ordinate with each other such that the mutual interference caused by their uplink radio resource allocations is mitigated.

5. General X2 management and error handling functions.

Answer 2

X2 interface is inter eNB interface which provides the control & data plane for UEs performing inter eNB and intra-MME handovers. It helps in minimizing the handover related signaling going through the EPC and also by having Direct tunnels between the eNBs helps in buffering the downlink traffic until successful handover.
For more details refer,
http://tech.queryhome.com/9344/can-any-one-explain-about-x2-and-s1-handover-in-lte#.Uhh2vH-4VIo