Apparatus and method for controlling transmission probability of slotted-ALOHA system based DS/CDMA

摘要

PURPOSE: A method and a system for controlling a transmission probability in a DS/CDMA-based S-ALOHA(Slotted-Additive Links On-line Hawaii Area) system are provided to guarantee the fairness between terminals without lowering a system throughput by determining the transmission probability, divided into an initial transmission probability and a retransmission probability, for a user for the transmission of the next slot and reporting it to all terminals. CONSTITUTION: A system for controlling a transmission probability in a DS/CDMA-based S-ALOHA system sets the initial transmission probability(P) of a packet to "1"(ST11). Then the system checks the state of a buffer(ST12). As a result, if the buffer is not empty, the system calculates the value of the initial transmission probability(P)(ST13). After calculating the initial transmission probability(P), the system transmits the packet data(ST14). Then the system checks whether an ACK signal for the transmitted packet data is received(ST15). If the ACK signal is not received, the system applies a retransmission probability(rtx_prob) method(ST16). However, in case that the ACK signal is received, the system applies an initial transmission probability(ntx_prob) method(ST16).