For instance, a spectrally inefficient constant-envelope modulation is very resistive to nonlinear effects. But both good devices and also low loss and high isolation interconnects are needed. Software oriented radio has drawn much attention. However, often software issues and digital circuits issues are emphasized while the RF front end is sometimes neglected. Therefore, front-end architecture should be included in the studies for software radio.
Smart antennas are another example where the software and hardware collaborate well.
Integrated antennas alleviate some of the hardware difficulties associated with smart antennas. Also, reconfigurable circuits and antennas should play important roles in developing the smart antenna. Three-dimensional integration schemes are required to provide communication systems that are very small, very low in weight and very low in cost without compromising performance. The use of heterogeneous materials for the circuits and devices incorporated in the system may lead to unique solutions in integration and packaging. The development of RF MEMS also provides new directions with the possibility of new functions and system architectures.