基地局間インタフェースを用いた基地局間協調送信制御のフィールド実証実験

摘要

Coordinated Multi-Point (CoMP) transmission, in which multiple base stations (BSs) transmit their signals in a coordinated way, is attracting attention as a promising technique to improve cell-edge throughput. We have proposed the cooperative transmission control method that can improve cell-edge performance by muting the interference signal coming from the other BSs, and we have evaluated that cooperative method by computer simulations and experiments. However, the previous study was "centralized cooperation" which achieve cooperative control only among BSs located in the same place (which the same cooperative cluster), so that we could not improve cell-edge performance at cluster edge, since BS cooperation is possible only among BSs in the same cluster. Therefore, we proposed "distributed cooperation" that enables cooperation among arbitrary BSs by utilizing inter-BS interface and evaluated the proposed method by computer simulations. In this paper, we develop a prototype system to demonstrate the feasibility and the performance of the proposal. Through laboratory and field experiments, we show that the proposal works well with real equipment and that cell-edge UE throughput performance can be improved drastically.%セル境界スループットを改善する技術として，基地局間で協調して信号を送信する基地局間協調が注目されている.筆者等はこれまで簡易に実現できる基地局間協調技術として強い干渉を及ぼす隣接基地局の信号送信を適応的に停止制御する基地局間協調送信制御を提案し，計算機シミュレーション及び試作装置を用いた実証実験により評価を行っている.これまでの検討は，複数の基地局を1ヶ所に設置し，それらの基地局(協調クラスタ内基地局)間だけで協調制御を実施とする"集中制御型の協調送信制御"であった.この検討では，同一の協調クラスタ内の基地局数に制限があるため，異なる協調クラスタに含まれる基地局とは協調できない課題があった.そこで筆者等は基地局間ィンタフエースを用いて任意の基地局間で実行可能な"分散制御型の基地局間協調送信制御"を提案し，その効果を計算機シミュレーションで明らかにした.本稿では，分散制御型の基地局間協調送信制御装置を試作し，それを用いて基地局間協調送信制御の適用効果を室内及びフィールド実験により明らかにする.