Multivariate signaling using multiple-in multiple-out (MIMO) configurations, increases the Shannon capacity of communication links, several fold. Among existing schemes that aim at realizing these predicted gains in practical scenarios, e.g., at high transmission rates or when the transmitter lacks channel state information, are orthogonal space-time block codes (STBCs), which are now known to display good performance characteristics, when concatenated with conventional trellis codes. It is shown that the only full-rate orthogonal STBC (for frequency-flat fading channels) achieves the (2,1)- channel capacity for single-sensor reception, and a full-rate block-orthogonal STBC is developed for broadband channels. While this STBC is easily adapted for use in the code division multiaccess down-link, a similar technique is necessary for the uplink, where performance degrades in fading media at high system loads. A simple signature-time transmit diversity paradigm, requiring just a single-sensor transmit-antenna at the mobiles, is shown to counter these degradations, in conjunction with iterative minimum mean square error (MMSE) multiuser decoding, at the base stations. Finally, an efficient layered space-time signaling technique for trellis coded packets, in systems with multisensor transmit- and receive-antennas, as in peer-to-peer communication environments, is proposed. With iterative MMSE decision feedback equalization and multistream decoding, it is observed to deliver significant fractions of the predicted MIMO throughputs.