Noncoherent MIMO Signaling for Block-Fading Channels: Approaches and Challenges

The majority of existing wireless communication systems relies on training-based signaling, i.e., schemes that rely on accurate channel estimates for detecting the transmitted symbols. Training requires its own hardware and algorithms and consumes a significant portion of the channel coherence interval, which is typically short in vehicular communications. The drawbacks of training can be alleviated by using noncoherent signaling schemes, which dispense with the training phase altogether. We will focus on a particular class of such schemes, i.e., Grassmannian signaling. This scheme is optimal for high signal-to-noise ratio (SNR) communication over noncoherent block-fading channels, which are likely to arise in many future networks.