With the rapid diffusion of mobile terminals in recent years, the number of the Internet access from mobile terminals has been drastically increasing. In this environment, the condition of channels changes greatly due to moving terminal locations, and transmission errors frequently occur as a result. Retransmitting the dropped packet can usually correct the errors. However, when burst errors occur, retransmission repeats and the throughput of the whole base station degrades. Since the throughput per terminal depends on the channel condition, the throughput between terminals differs each other. This paper aims at improving the throughput at base stations and the throughput unfairness per terminal, and proposes a new packet transfer scheduling scheme with throughput compensated considering radio conditions. Our proposed method consists of two mechanisms. One is a throughput control mechanism which compensates the throughput to each terminal. The other is a transmitting control mechanism which inspects fine channels where little error occurs. Cooperating these two mechanisms, if a channel condition is good, packets belonging to this channel is prioritized for the purpose of higher transmission efficiency. Meanwhile, the proposed test protocol data unit (PDU), one of our proposals, is sent to a bad channel to confirm if the channel is restored or not. After confirming the restoration, the degraded throughput is compensated. The use of the test PDU controls the channel properly without wasting radio link bandwidth and can achieve the fairness between each terminal. Computer simulations have evaluated the performance of our proposed method. Our proposed method is verified its efficiency with the results showing the improvement of the throughput at base stations and unfairness per mobile terminal.
['Jiro Fukui', 'Norio Yamagaki', 'Hideki Tode', 'K. Murakami']
Packet transfer scheduling scheme with throughput compensated considering wireless conditions