Interference Measurement Scheme for CoMP in LTE-Advanced Downlink

摘要

Coordinated multi-point (CoMP) transmission and reception is considered to be a promising technology to improve the cell-edge user throughput by mitigating the inter-cell interference, and it is expected to be specified in long-term evolution (LTE) Release 11 in 3GPP. For CoMP, the channel state information (CSI) feedback mechanism is a key factor in achieving a better throughput performance gain. This paper proposes two interference measurement schemes for CoMP in the LTE-Advanced downlink. In the proposed schemes, the existing CSI reference signal, which is used for CSI measurement, is fully utilized considering the impact to legacy user equipment, and a sufficient number of configurations for interference measurement resources are established to facilitate operator cell-planning efforts. Based on multi-cell link level and system-level simulations, we also confirm that the proposed schemes achieve an accurate interference measurement for a single transmission point and CoMP operation.%LTE-Advanced (LTE Release 11)では，1つあるいは複数のUE (user equipment)に対し複数の送信ポイントが協調して送受信の信号処理を行うセル間協調送受信技術の検討が行われている。下りリンクセル間協調送信では，様々なセル間協調送受信技術を実現可能な柔軟性，高精度かつ高効率な測定精度，後方互換性等を考慮したチャネル品質情報報告法の実現が求められる。本稿では，これらの要求条件を考慮しつつ，チャネル品質情報測定に用いる干渉信号電力推定法の検討を行う。具体的には，既存の参照信号（CSI-RS: channel state information reference signal)を用いつつ，多数の干渉測定リソースを確保可能な干渉信号電力推定法の提案を行う。提案法の適用により，セルプランニングエフォートを低減しつつ、シングルセルおよびセル間協調送信の双方において高精度な干渉推定精度を実現可能となることを示す。