Burst is an atomic bandwidth allocation unit in IEEE 802.16 OFDMA systems. Due to the satisfaction of the rectangular mapping constraint in the downlink allocations, bandwidth called OFDMA slots may be over-allocated, resulting in the wastage of the downlink bandwidth. In order to alleviate the wastage of downlink bandwidth, this paper proposes a Burst Overlapping and Scheduling Scheme, termed BOSS, for IEEE 802.16 OFDMA systems. The BOSS is to alleviate the number of over allocated OFDMA slots caused by the allocation constraint of downlink bandwidth by means of allowing two neighboring bursts to share these over allocated slots. Simulation results show that the proposed mechanism can increase not only the network throughput, but the subchannel utilization.