The IEEE 802.15.4 standard for the Low Rate Wireless Personal Area Networks (LR-WPANs)is popular and widely used for many areas of applications. The standard uses slotted CSMA/CA protocol in it's contention access period (CAP) in the beacon enabled mode. The protocol adopted a Binary Exponential Backoff (BEB)algorithm. In this paper, we investigate the saturation throughput of this standard using the existing BEB algorithm and compare it with three other backoff schemes - Exponential Increase Exponential Decrease (EIED), Exponential Increase Linear Decrease (EILD) and Exponential Increase Multiplicative Decrease (EIMD) algorithms. From the simulation results, it is found that EIED, EILD and EIMD perform better than the BEB for the higher loads. The EIED produces the highest throughput among all of these schemes.