how-to-perform-a-x2-ho.md

+# Tutorial on how to perform a intra-frequency X2 Handover
+
+## X2 Handover setup 
+
+
+## Steps
+The experiment methodology/steps are described in the following:
+1. eNBs are synchronized in frequency and frame/subframe timing using GPS
+1. eNB are operating on the same band, frequency, and bandwidth  (e.g. band, 2.6GHz,  7 10 MHz)
+1. Both eNBs are connected to the same EPC that supports the path switch required for X2 HO
+1. UE measures the source/target cell’s signal quality based on the different cell IDs
+1. UE is initially attached to eNB 0 and its mobility is emulated using either real mobility or an attenuator allowing the UE to handover from eNB0 to eNB1 that causes the related X2 HO signalling to be triggered as a consequence of the A3 event
+1. UE is connected to eNB1 after the HO process
+
+In the proposed setup, different possible deployed scenarios can be considered for experimentation, e.g., a) different types of traffic (TCP/UDP) in UL/DL, b) successful/failed HO based on UE’s emulated mobility as well as different OAI network measurements, e.g., packet loss, delay, RSRP/RSRQ etc.
+
+## Attenuator 
+In addition, [octoBoxquadAtten](http://www.octoscope.com/English/Products/Ordering/octoBox/quadatten.html)  modules are used as attenuators on both the two eNBs to model the user equipment (UE) mobility (fading effects creation) in order to send the A3 event included in its E-UTRAN RRC Measurement report for triggering the HO in the eNB side. Specifically, the selected attenuators offer stable attenuation accuracy via wide choice of attenuation (63 dB range), frequency ranges (DC to 6000 MHz) and step sizes (0.5 step). In addition, the module can be controlled remotely through Ethernet interface (attenuation control unit). 
+
+![octoscope](/uploads/0f34dd2f59a8a3d45caa0127e0069d3d/octoscope.jpg)
+
+## Additional Materials 
+ 1. [Config files]
+ 1. [Wireshark traces]
+ 1. [Youtube Video](https://youtu.be/KlwampmhFxw)
+
+