Downstream Bandwidth estimation in presence of RTS/CTS

With the $RTS/CTS$ handshake, each data frame transmission incurs a total delay ($T$) given by Eq. (5), the sum of delays incurred by the $RTS$, $CTS$, data and $ACK$ frames respectively.

$$T = T_{R} + T_{C} + T_{D} + T_{A}$$ (5)

Since the frame transmission rules for an $RTS$ and beacon frames are the same, the delay incurred by an $RTS$ frame can be estimated using Eq. (6), as the sum of $T_B$ and transmission delay (all MAC control frames are transmitted at the base rate).

$$T_R = T_B + \frac{RTS}{R_b}$$ (6)

Upon receiving a $RTS$ frame, a receiver waits a duration of time equal to $SIFS$ and transmits a $CTS$ frame, again at the base rate $R_b$. The $CTS$ frame is transmitted at the base rate $R_b$ and its delay is given by:

$$T_C = SIFS + \frac{CTS}{R_b}$$ (7)

The delay incurred by the data frame is given by:

$$T_D = SIFS + \frac{DATA}{R}$$ (8)

Lastly, the computation of $T_{A}$ remains the same across both schemes and is given by Eq. (3). The potential bandwidth $B$ is then obtained using Eq. (4).