In presence of a link quality mismatch between the backhaul and access links of the relay node, we analyze the impact of the buffer size on the occurrence of undesirable events such as buffer overflows or underflows on the LTEAdvanced system. Moreover, based on simulations, we find out that the size of the buffer at the RN can positively influence the throughput performance of the served users. Finally, we observe that in different relaying conditions, the buffer size setting plays an important role on the overall system performance, especially in terms of underflow and overflow occurrence.