Immediate transmission scheme of s-ALOHA with PCT (power control during transmission) method

The authors present a new access scheme for packet radio networks with variable length packets, called S-ALOHA/IT (slotted ALOHA with immediate transmission) in which a packet can be sent immediately unless it overrides the slot boundary. In the s-ALOHA/IT, the PCT (power control during transmission) method is added for improving efficiency. The basic idea of the PCT method is to control the packet transmission power increasingly as a time function and to lead the capture effect. By the PCT method, some packets are successfully transmitted even when packet collisions occur. In addition, the initial power is also varied to introduce the capture effect among collided packet. A performance comparison of the s-ALOHA/IT is carried out with the conventional s-ALOHA by using computer simulation. In all cases, the throughput of s-ALOHA/IT is about twice that of the conventional s-ALOHA