On the average staleness of global channel state information in wireless networks with random transmit node selection

This paper studies the average staleness of global channel state information (CSI) in fully-connected time-slotted wireless networks with time-varying reciprocal channels where, in each time slot, one node is equiprobably selected to transmit and disseminate CSI. The proposed protocols are compatible with the random nature of transmissions and they embed CSI in existing network traffic. A staleness framework is developed for quantifying the usefulness of global CSI and closed-form expressions are derived for the average staleness of two protocols with different amounts of overhead: (i) dissemination of a single channel estimate in each packet, and (ii) dissemination of all estimated CSI in each packet. Analysis shows the average staleness scales as O(N2) in both cases but "all CSI dissemination" provides better average staleness except when the amount of data in each packet is small. Simulation results confirm the analysis and quantify average staleness in terms of the network parameters.