Recently clear market needs are observed to further boost the downlink peak data rate to 1.2Gbps and 1.6Gbps, which requires support of 8 layers on a single carrier to increase the spectrum efficiency. To achieve that goal, utilization of 8 receiving antenna (8Rx) in downlink is a must. Correspondingly, the new UE DL category 18 and 19 were introduced in TS 36.306 with square brackets. And RAN4 is expected to specify the new RF, RRM and demodulation performance requirements for them. Many benefits can be achieved by 8Rx UE. It can significantly improve the downlink throughput for a single user across the cell, and also enhance the coverage for the cell edge users. Considering that 256QAM and even higher order modulation scheme was and will be introduced, 8Rx would be one of the efficient and robust ways to make the use of them feasible in the practical operating SINR range. Besides, 8Rx UE with IRC has the capability of cancelling more inter-cell interferers. To study the performance benefits of 8Rx, a new study item "Study on LTE DL 8Rx antenna ports" was approved at RAN #76 [1], and the current document summarizes the study done under this study item.

The study item should fulfil the following objectives:

• Evaluation of PDSCH demodulation performance with 8Rx for the transmission with rank lower than or equal to 4
  • Identify the scenarios for the evaluations
    • Identify the necessary parameters including MCS, rank (≤4), antenna configuration and MIMO channel correlation, and propagation conditions
    • Minimize the evaluation case numbers as much as possible
  • Run link level simulations, and compare 8Rx performance with 4Rx under the identified scenarios to investigate the performance gain
    • Use MMSE-IRC as the reference receiver
• Evaluation of PDSCH demodulation performance with 8Rx for the transmissions with rank higher than 4
  • Identify the scenarios for the evaluations
    • Identify the necessary parameters including MCS, rank (>4), antenna configuration and MIMO channel correlation, and propagation conditions
    • Minimize the evaluation case numbers as much as possible
  • Run link level simulations, and investigate the operating SNR for higher layer transmission
    • Use MMSE-IRC as the reference receiver
• Evaluation of PCFICH/PDCCH demodulation performance with 8Rx
  • Identify the scenarios for the evaluations
    • Identify the necessary parameters including CCE levels, antenna configuration and MIMO channel correlation, and propagation conditions
    • Minimize the evaluation case numbers as much as possible
  • Run link level simulations, and compare 8Rx performance with 4Rx performance under the identified scenarios to investigate the performance gain
    • Use MMSE as the reference receiver
• Based on the above evaluation results, identify the UE RF, RRM and UE performance requirements, which will be specified.
  • Identify the scope and objectives of UE RF requirements for 8Rx
    • Decide the supported LTE bands for 8Rx
  • Identify the scope and objectives of RRM core requirements for 8Rx
  • Identify the scope and objectives of RRM performance requirements for 8Rx
  • Identify the scope and objectives of UE performance requirements for 8Rx
    • UE demodulation requirements
    • CSI requirements