Physical layer service integration in wireless networks: Signal processing challenges

It is becoming more important that next-generation wireless networks wisely integrate multiple services at the physical layer to increase spectral efficiency. In this article, physical layer service integration in wireless networks is considered, where senders not only transmit individual data to certain receivers but also integrate additional multicast or confidential services that have to be kept secret from nonlegitimate receivers. In this context, physical layer security techniques are becoming a promising complement to cryptographic techniques since they establish security using only the physical properties of the wireless channel. State-of-the-art solutions for certain important communication scenarios are discussed, and signal processing challenges and promising research directions are identified.