Multiantenna energy detection of PAM symbols without spatial signal cross-products

In this paper, we consider multiantenna energy detection (ED) of nonnegative pulse-amplitude-modulated (PAM) symbols suitable for low-power and low-complexity short-range communication radios using a very wide bandwidth or high centre frequency. We present a general condition which leads to the cancellation of the spatial cross products between the distinct PAM space-time coded signals at the output of an ED-based multiantenna diversity decoder. Moreover, it is shown that our existing analysis approach for single antenna ED-PAM systems in very wideband lognormal multipath fading channels can be conveniently extended for fast evaluation of spatial diversity gain and correlation effects between antenna elements in multiantenna ED-PAM systems. The error probability performance is illustrated for the selected system parameters by using the proposed analysis tool. The accuracy of the analysis approach is demonstrated with appropriate simulations.