Analysis and experimental evaluation of rate adaptation with transmit buffer information

In hardware, packet loss may happen due to overflow from a finite-depth transmit buffer. To prevent such losses and further improve rate selection, we exploit statistical knowledge of transmit buffer occupancy and source packet distribution in IEEE 802.11-based systems, which have variable frame slots. We consider a traditional method of rate adaptation based on channel quality information and evaluate the throughput gain in hardware when the buffer occupancy and source packet distribution information are known. Our optimization objective is to maximize the throughput with constant transmit power since most IEEE 802.11 APs and nodes operate in this manner. We also derive an upper bound of the improvement introduced by exploiting the offered load distribution and buffer status information. By evaluating the effect of diverse buffer sizes with different packet arrival distributions, both our theoretical analysis and our experimental results show that the throughput can be greatly improved in many cases when the source packet distribution and buffer status information are exploited.