In some countries, several vehicles move with the speed over than 300km/h, e.g., Japan Tohoku Shinkansen (320km/h), German ICE (330km/h), AGV Italo (400km/h), and Shanghai Maglev (430km/h). With the increase of high speed moving environment, the demand of using mobiles in such an environment in E-UTRA is growing larger. Therefore, it is important to guarantee the performance under such environment in E-UTRA. However, in the current 3GPP specifications, since the maximum speed guaranteed in BS performance is up to 350km/h, it would be challenging to keep up with the speed of vehicles moving around 400km/h. In addition, since the speed guaranteed in BS demodulation, UE demodulation, and UE RRM specifications are different, even though the speed up to 350km/h is guaranteed in BS specification, the same speed cannot also be ensured in UE demodulation and UE RRM specification as well. Given the fact above, it is essential to comprehensively revisit and enhance the existing requirements to ensure the system performance under high speed environment in E-UTRA. In addition, due to different commercial network deployment scenarios of operators and surrounding environments (downtown/suburban or mountain areas), there may exist some issues/scenarios that the current specified requirements may not be able to cover and to guarantee the solid performance. Therefore, it would be worth investigating potential issues/scenarios and identifying some new requirements to ensure them from various aspects where the current requirements are missing now. The present document is the Technical Report for the Study Item on performance enhancements for high speed scenario in LTE.