In this paper, we propose and evaluate the performance of Wireless ATM MAC layer protocol to support efficiently various ATM traffics, such as CBR, VBR, ABR and UBR, in wireless ATM network environments for reverse and forward link. The proposed MAC protocol could extend efficiently the service discipline of ATM traffics from wired network to wireless ATM network environments. Thus, available bandwidth, which is remained except the bandwidth for CBR and VBR traffics, could be effectively allocated to ABR and UBR traffics. Especially, in view of reverse link, two-phase scheduling algorithm supports successfully variable characteristics of VBR traffic. And, in view of forward link, 'Wireless Dynamic Weighted Earliest Deadline First' scheduling algorithm minimizes the mean cell delay and required buffer size. Simulation results show that proposed method provides effective performance in wireless ATM environments.

In this paper, efficient data transmission methods in wire and wireless interworking environments are studied in the case of handover occurring. To provide efficient mobile data service based on TCP, the wire and wireless interworking module with analysis function of TCP frame header protects the duplicated transmission of TCP frames. Also, by using the forwarding mechanism of status information and buffered data in the interworking module, it is possible to recover frame loss occurring in handover quickly. According to simulation results, proposed method has better performance than conventional method in view of throughput and delay. The reason is due to the fact that duplicated transmission is prevented and data recover is performed very quickly because buffered data is forwarded without loss in the case of handover.

To support efficiently the high-speed service and the multimedia service in mobile communication environments, network architecture is generally based on small cell radius structure to increase the wireless channel capacity. In a small cell radius structure based mobile network environment, a mobile station with large mobility should perform frequent handover. Thus, advanced handover mechanism should be provided, and must be done fastly. For these reasons, we suggest the efficient handover mechanism based on forward handover method in this paper. Proposed handover mechanism could support fast handover procedure, and is performed by using optimized path. Also, proposed handover mechanism could support QoS (Quality of Service) attribute of multimedia traffic during handover procedure. We evaluated the performance of proposed handover mechanism, and analysis results show that the suggested forward handover mechanism has less blocking ratio and lower delay than conventional backward handover mechanism.