Wireless Robotics: Generalization of an Efficient Approach with Multi-h CPM Signaling and L2-Orthogonal Space-Time Coding

Abstract

Wireless Robotics has become an important research topic in the last two decades. The need of controlling a robot to perform tasks remotely has significantly increased with the number of applications in fields like medicine and military, among many others. Taking advantage of current standards like Bluetooth and Wifi, Wireless Robotics calls for low power consumption components, robustness and high data rate through the wireless channel. This call can be fulfilled with a reliable signaling format, satisfying the needs of low power consumption and high spectral efficiency. Besides, continuous phase modulation (CPM) has gained increasing attention due to its favorable trade-off between power and bandwidth efficiency. Multi-h CPM recently appeared as a generalization of single-h schemes so as to further decrease the need for bandwidth expansion over the wireless channel. Despite the interesting characteristics of CPM, the decoding of the received signal is particularly difficult in a multi-path wireless environment with no diversity. To provide some level of diversity, several authors have proposed to combine CPM with space-time block coding. A new family of codes for CPM, based on $L^2$-orthogonality was recently introduced in Hesse et al. (IEEE Trans Commun 59(11): 3158–3166, 2011). These full rate codes achieve full diversity and a low decoding complexity. In this paper, we detail a non trivial extension of these $L^2$-orthogonal space-time codes using multi-h signaling schemes. These new codes still achieve full diversity but a better spectral compactness by utilizing the available communication bandwidth more efficiently. Also, the decoding complexity is greatly decreased by using only one correlation filter bank for the detection of all transmitted signals.