| Popis: |
Rate adaptation is a MAC-layer mechanism in IEEE 802.11 networks that ensures efficient utilization of constantly varying wireless channel. For broadcast communication, however, the current practice is to send data at base rates (i.e., 1 or 2 Mbps in 802.11b/b+g and 6Mbps in 802.11a/g), leaving the channel capacity significantly underutilized. In this paper, we present a practical rate adaptation framework designed for broadcasting of streaming data to improve the channel utilization of 802.11 networks. The proposed framework jointly selects the data rate and the error protection level of FEC in a novel manner, and does not require changes to either existent applications or to the 802.11 standards - thus can be deployed in existing 802.11 networks. Using the performance measurement study in various live networking environments, we show that the proposed scheme provides substantial improvement in wireless channel utilization (more than 10x improvement compared to the current broadcast mode) and can adapt to different operational environments. |
