On the age of Channel State Information for non-reciprocal wireless links

We present a framework to study the effect of outdated Channel State Information (CSI) on the performance of a non-reciprocal wireless link. The proposed framework is based on the new concept of age of information. We adopt the Gilbert-Elliot channel model to obtain analytic results regarding the use of periodic CSI feedback and investigate the effect of the age of CSI when multiple orthogonal resource blocks are assigned to a communication link. A general utility function is defined as performance metric, which accounts for the cost of feedback. Our work improves the comprehension about the age of channel state information and its effect on the performance of communication links, which is fundamental for designing efficient adaptation functions and feedback protocols.