  Simultaneous machine translation (SiMT) outputs the translation while
receiving the source inputs, and hence needs to balance the received source
information and translated target information to make a reasonable decision
between waiting for inputs or outputting translation. Previous methods always
balance source and target information at the token level, either directly
waiting for a fixed number of tokens or adjusting the waiting based on the
current token. In this paper, we propose a Wait-info Policy to balance source
and target at the information level. We first quantify the amount of
information contained in each token, named info. Then during simultaneous
translation, the decision of waiting or outputting is made based on the
comparison results between the total info of previous target outputs and
received source inputs. Experiments show that our method outperforms strong
baselines under and achieves better balance via the proposed info.
