Performance evaluations for hybrid IEEE 802.11b and 802.11g wireless networks

The IEEE 802.11g standard has been proposed to enhance the data rate of wireless LAN connections up to 54Mbps, while ensuring backward compatibility with legacy 802.11b devices at the same time. However, in a hybrid 802.11b/g network, the throughput of 802.11g devices is compromised because of not only the overhead to interoperate with 802.11b devices, but also the unbalanced medium contentions between devices with different versions of the standard. We propose a hybrid Markov-chain based model to quantify this throughput reduction effect in 802.11b/g mixed scenarios. The analytical model is further verified with simulations and field measurements under different station numbers, data rates, and data packet sizes. In addition, a simple frame-bursting technique is shown to balance the throughput between 802.11b and 802.11g stations.