| 摘要 |
PURPOSE: A wireless ATM medium access control protocol unit is provided so that delay and Q size can be reduced and reliability of the service can be improved by efficiently supporting VBR, CBR and ABR servers and scheduling cells according to a deadline. CONSTITUTION: In a forward MAC(Medium Access Control) protocol based on a WDWEDF(Wireless Dynamic Weighted Earliest Deading First) and packing, cells are received from a network, and stored in a temporary buffer of each link. When a fixed size time frame is periodically generated, transmission cells are selected according to the WDWEDF algorithm. Thereafter, the packing procedure is performed on the cells in order to reduce a physical transmission overhead. In the packing procedure, the transmission cells are grouped in virtual channel units on the basis of scheduling table information of the WDWEDF. Here, a frame and an MPDU(Medium Access Control Protocol Data Unit) overhead for the actual transmission, and a change period for change of an up/down link are inserted into the grouped cells. The generated time frame is transmitted to terminals through the forward link. Therefore, a delay and a buffer size can be reduced by introducing an EDF(Earliest Deadline First) algorithm. In addition, the WDWEDF algorithm efficiently supports VBR(Variable Bit Rate), CBR(Constant Bit Rate), ABR(Available Bit Rate) and UBR(Unspecified Bit Rate) traffics.
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