System Distortion Exponents of Two-Way Relay Networks

Distortion exponent (DE) is the asymptotic exponential decay rate of the expected distortion between a source and its reconstruction in the high-SNR regime. This paper presents two improvements to the existing DE analyses of two-way relaying networks, where two users communicate in both directions with the help of a relay. First, we allow the users to have different bandwidth ratios, and derive the corresponding achievable DE regions of the system with different source coding, transmission, and relaying strategies. Secondly, we propose a new performance measure called the system distortion exponent (SDE), which characterizes the weighted average of the two distortions. The SDEs of the aforementioned scenarios are also derived.