I. Introduction
Feedback control problems with limited information have been an active research area for years, as surveyed by Nair et al. [1]. Information flow in a feedback loop has been an important factor in many application-related scenarios, not only because of bandwidth constraints, but for cost concerns, physical restrictions, and security considerations as well. Besides the aforementioned practical motivations, the question of how much information is required to achieve a certain control objective is quite fundamental and intriguing from the theoretical point of view. In the study of feedback control problems, it is common to characterize the limitation on information flow as a finite data transmission rate achieved by using sampled and quantized measurements to generate the control input (see, e.g., [2], [3] and [4], Ch. 5), which is the modeling framework adopted in this paper.