Infostations serve a demand for multimedia services with high quality and high data rate. The challenge for Infostation system design is how to download as many information bits when a mobile user drives through an Infostation cell. A variable rate TDMA/TDD radio architecture is chosen for study and experimental implementation because of its flexibility in a multi-user environment. A symbol rate and rate compatible punctured convolutional code controlled adaptive transmission scheme is proposed for the Infostation radio design. Data throughput is analyzed for a mobile user passing through an Infostation cell. The analysis indicates that three data rates at 0.25, 1.0 and 2.0 Mbps achieve greater than 85% of the theoretical throughput while simplifying the implementation. The punctured convolutional code is studied to maximize the Infostation throughput. A recommendation is made to use rate 1/2 coding scheme. An efficient rate adaptation algorithm is proposed and it can track the Rayleigh fading channel well and the capacity loss is negligible in various conditions.

The Infostation concept has been proposed to provide convenient and cost effective access to high-speed mobile data services. An efficient IP packet transmission protocol is required to compensate for the high error rate inherent to fading radio channels. In this paper, a novel link layer retransmission scheme is proposed. Using the channel state and fading state estimators, the scheme adjusts the retransmission parameters dynamically in order to achieve the optimum performance under time-varying channel conditions. A theoretical analysis is presented for the case of a random error channel. Furthermore, a simulation tool is developed for evaluating the performance of the scheme in a fading channel with various parameters. The analysis and simulation results show that this new retransmission scheme can provide substantial improvement over traditional schemes. It gives a robust performance in both slow and fast fading conditions. In addition, the algorithm's sensitivity to parameter values and channel characteristics, such as Doppler frequency and fading statistics, is investigated. A unique attribute of this algorithm and performance analysis is that throughput is evaluated in IP packets rather than in physical layer packets.