Signal processing challenges for wireless communications

Wireless communications allow for the application of a number of signal processing techniques. However, in many instances the success of the application depends on the proper accounting for the interaction of the signal processing problem with other disciplines such as propagation and channel modeling, communication and information theory, and processor circuit architectures. We discuss the incidence of propagation studies and channel modeling on channel correlation and hence on channel estimation performance (orthogonality of pilots), the interaction between modulation technique and the ease of training based channel estimation, the interaction between transmission scheme (continuous or block-wise) and temporal fading modeling and handling, modulation and signal processing (linear preceding) for diversity exploitation, approximate normal equation solutions for various signal types (speech vs CDMA, sparse significant correlations vs. dense weak correlations), interaction between channel modeling and CDMA receiver circuit architecture, higher-level adaptivity in adaptive filtering (filter order, temporal variation scale) and robustness in receiver design with estimated parameters.