This paper analyzes and compares performances of several improved medium access control (MAC) protocols and CSMA/CA protocol when the data rate is high (at least 1 Gbps), then proposes a novel MAC protocol, called pseudo-time division backoff scheme (PTDBS). The proposed scheme can be implemented in IEEE 802.15.3c easily and it can become an improved access control method in contention access period (CAP) for existing IEEE 802.15.3 MAC. PTDBS has been validated using OPNET network simulator. The results show that PTDBS offers higher throughput, lower delay and completion rate of close to one when the traffic load is heavy compared with the CSMA/CA protocol and other improved MAC protocols.