We propose a novel workload-dependent queuing model for a wireless router link which employs active queue management (AQM) and is offered with a number of persistent Transmission Control Protocol (TCP) flows. As opposed to existing work that focus only on the average queue occupancy as the performance metric of interest, the proposed analytical method obtains the more information-bearing steady-state queue occupancy distribution of the wireless AQM link. Simulations are performed to demonstrate the accuracy of the proposed model in both wireline and wireless scenarios. With the intention of maximizing TCP throughput, this analytical method is used to obtain guidelines for setting the target wireless packet error rate (PER) for a PER-based traffic-agnostic link adaptation scheme.