Future Broadband Packet Radio Access and Its Field Experiments

This paper presents a broadband packet radio access scheme based on Orthogonal Frequency Division Multiplexing (OFDM) based access in the downlink and single-carrier based access with spreading including low-rate channel coding in the uplink for the systems beyond IMT-2000. In our design concept for radio access in both links, the spreading factor including the channel coding rate is optimally controlled so that the system capacity is maximized according to the cell configuration, i.e., whether cellular cell or local environments, by taking advantage of one-cell frequency reuse, and orthogonality of simultaneous users in the frequency domain is used. We show that peak throughput values of greater than 100 Mbps and 20 Mbps are achieved using variable spreading factor (VSF)-Orthogonal Frequency and Code Division Multiplexing and broadband DS-CDMA access in a real field environment using the implemented base station and mobile station transceivers employing 100-MHz bandwidth in the downlink. Furthermore, we present results of a real-time 1-Gbps packet transmission with the corresponding frequency efficiency of 10 bits/second/Hz in the downlink employing VSF-Spread OFDM radio access utilizing 4-by-4 multiple-input multiple-output multiplexing.