Optimizing the frame length of IEEE 802.11 DSSS with CRC error detection

In this paper, we aim at investigating how various kinds of design parameters in IEEE 802.11 wireless networks affect the system throughput. It is focused on the design of the optimal length of the frame body from the viewpoint of cross-layer interaction between the MAC and PHY. The following results are obtained: 1) The optimal length of the frame body in logarithmic scale, expressed as log L_f,opt, can be coarsely approximated by a linear function of the signal-to-noise power ratio (SNR) E_b=N₀ (in dB) and finely approximated by a second-order polynomial of E _b=N₀; 2) The coefficients of the aforementioned approximation functions depend only on the data transmission rate and other parameters specified in the protocol, and they weakly depend on the access mechanisms; 3) The number of active nodes has little effect on L _f,opt, especially when the SNR is low; and 4) The system throughput is sensitive to the length of the frame body L_f when the SNR is low, while it is insensitive to L_f in a considerably large neighborhood of L_f,opt when the SNR is high.