Recent research has developed a new, entirely digital architecture, called X-ORCA, that determines the phase shift of two periodic signals with a resolution as good as about 20 ps. This paper incorporates the X-ORCA system into a wireless experimental setup to form a localization system. The practical experiments utilize a 2.484 GHz transmitter and run the X-ORCA core on a Cyclone II FPGA. The results indicate that this simple localization system easily yields a spatial resolution in the sub-millimeter range.

In this paper, we provide a semi-analytical method for predicting the upper and lower bound of the end-to-end mutual information for a relay network with practical codes and different combining and decoding mechanisms. Especially in the case of non error-free decoding at the relays, the prediction can be used to significantly improve the performance of the system under consideration.

Analyzing the capacity of relay networks is often based on the max-flow min-cut theorem providing an upper bound on the true capacity which is generally still unknown. This paper analyzes the achievable rates of a simple relay network by a semi-analytical approach considering ideal capacity achieving codes of appropriate rates and optimum symbol-by-symbol soft-output decoding at the relay. Applying the information combining technique, regions are illustrated where the upper bound provided by the max-flow min-cut theorem can be reached. Moreover, the results show that the lower bound obtained by the constraint of error-free decoding at the relay can be exceeded in many scenarios. Simulations with a nearly capacity achieving half-rate repeat accumulate code confirm the semi-analytic results.

Relay networks have attracted great attention in recent years due to their ability to extend the coverage of cellular systems. Their capacity is often analyzed by the max-flow min- cut theorem which provides an upper bound on the true capacity. However, the exact capacity is generally still unknown. This paper applies information combining to determine the achievable rate of a simple relay network. Presupposing an ideal code of appropriate rate and optimum symbol-by-symbol soft-output decoding at the relay, this semi-analytical approach delivers upper and lower bounds on the achievable mutual information of the network. The obtained results identify three different regions concerning the optimum rate of the code. Simulations of a nearly capacity achieving half-rate repeat accumulate code confirm the semi-analytic results.