A system for transmitting information as frames in digital format between users on a network using a single frequency and TDMA and/or CDMA communications. Broadcasting, multicasting and unicasting are provided, and communications may be part of a downlink and/or an uplink signaling scheme that allows user-user and user-central station communication. A synchronization segment or pre-amble for a frame may include identification of the source and/or the intended recipient. Walsh, Haar, Rademacher coding of selected frame components, among others, can be incorporated. Reed Solomon encoding, signal interleaving and intra-leaving, trellis encoding and turbo encoding are used for error detection and correction. The system provides two-way communication with the Internet and/or with a cellular network and/or for smaller networks of users.