Information rates for phase noise channels

Gerhard G. Kramer, Hassan Ghozlan

Gerhard G. Kramer

Luca Barletta

M. T. DiMario, L. Kunz, K. Banaszek +1 more

Abstract The achievable rate of information transfer in optical communications is determined by the physical properties of the communication channel, such as the intrinsic channel noise. Bosonic phase noise channels, a class of non-Gaussian channels, have emerged as a relevant noise model in quantum information and optical communication. However, while the fundamental limits for communication over Gaussian channels have been extensively studied, the properties of communication over Bosonic phase noise channels are not well understood. Here we propose and demonstrate experimentally the concept of optimized communication strategies for communication over phase noise channels to enhance information transfer beyond what is possible with conventional methods of modulation and detection. Two key ingredients are generalized constellations of coherent states that interpolate between standard on-off keying and binary phase-shift keying formats, and non-Gaussian measurements based on photon number resolving detection of the coherently displaced signal. For a given power constraint and channel noise strength, these novel strategies rely on joint optimization of the input alphabet and the measurement to provide enhanced communication capability over a non-Gaussian channel characterized in terms of the error rate as well as mutual information.

Luca Barletta

A new upper bound (UB) on the information rate (IR) transferred through the additive white Gaussian noise channel affected by Wiener's laser phase noise is proposed in the paper. The bound is based on Bayesian tracking of the noisy phase. Specifically, the predictive and posterior densities involved in the tracking are expressed in parametric form, therefore tracking is made on parameters. This make the method less computationally demanding than known non-parametric methods, e.g. methods based on phase quantization and trellis representation of phase memory. Simulation results show that the UB is so close to the lower bound that we can claim of having virtually computed the actual IR.

Jun Zhu, Ye Li, Ning Wang +1 more

To support downlink simultaneous wireless information and power transfer (SWIPT), energy harvesting mobile terminals (EMTs) need to be deployed closer to the base station than information mobile terminals (IMTs), in order to meet higher received power requirement. However, this raises a critical issue that the messages sent to IMTs are potentially eavesdropped on by EMTs, which experience better channels. In this letter, we study the effect of phase noise on the downlink SWIPT in secure massive MIMO systems, which degrades accuracy of the channel state information and in turn causes potential information leakage. We derive closed-form lower bounds on the worst-case secrecy rate achieved by each IMT and the energy harvested by each EMT. Numerical results reveal that the secrecy rate monotonically decreases as the phase noise variance increases, but the monotonicity does not hold for the harvested energy.