The 3GPP working group proposes the Long-Term Evolution (LTE) system as the 4G mobile communications technology. To reduce the transmission latency in the radio access network, Evolved Universal Terrestrial Radio Access Network (E-UTRAN), of LTE, the base station and radio network controller aremerged into a single network node, namely eNB. In E-UTRAN, the Stop-And-Wait Hybrid ARQ (SAW-HARQ) protocol in the Media Access Control (MAC) layer deals with transmission errors without the need to engage the ARQ protocol in the Radio Link Control (RLC) layer. The HARQ and ARQ protocols interact only in case of dealing HARQ residual errors. In this paper, we propose an analytical model to model the behavior of the HARQ–ARQ Interaction. Our analytical model is validated against the simulation experiments that provide more performance metrics (which cannot be obtained through our analytical model). Finally, we investigate the impacts of the HARQ–ARQ Interaction on the Protocol DataUnit (PDU) transmission delay based onour simulation experiments.Copyright©2009 JohnWiley&Sons, Ltd.