197 research outputs found
Upper Bound on the Capacity of Discrete-Time Wiener Phase Noise Channels
A discrete-time Wiener phase noise channel with an integrate-and-dump
multi-sample receiver is studied. An upper bound to the capacity with an
average input power constraint is derived, and a high signal-to-noise ratio
(SNR) analysis is performed. If the oversampling factor grows as
for , then the capacity pre-log is at
most at high SNR.Comment: 5 pages, 1 figure. To be presented at IEEE Inf. Theory Workshop (ITW)
201
Lower Bound on the Capacity of Continuous-Time Wiener Phase Noise Channels
A continuous-time Wiener phase noise channel with an integrate-and-dump
multi-sample receiver is studied.
A lower bound to the capacity with an average input power constraint is
derived, and a high signal-to-noise ratio (SNR) analysis is performed.
The capacity pre-log depends on the oversampling factor, and amplitude and
phase modulation do not equally contribute to capacity at high SNR.Comment: Extended version of a paper submitted to ISIT 2015. 9 pages and 1
figure. arXiv admin note: text overlap with arXiv:1411.039
Capacity Outer Bound and Degrees of Freedom of Wiener Phase Noise Channels with Oversampling
The discrete-time Wiener phase noise channel with an integrate-and-dump
multi-sample receiver is studied.
A novel outer bound on the capacity with an average input power constraint is
derived as a function of the oversampling factor.
This outer bound yields the degrees of freedom for the scenario in which the
oversampling factor grows with the transmit power as .
The result shows, perhaps surprisingly, that the largest pre-log that can be
attained with phase modulation at high signal-to-noise ratio is at most .Comment: 5 pages, 1 figure, Submitted to Intern. Workshop Inf. Theory (ITW)
201
Tight Upper and Lower Bounds to the Information Rate of the Phase Noise Channel
Numerical upper and lower bounds to the information rate transferred through
the additive white Gaussian noise channel affected by discrete-time
multiplicative autoregressive moving-average (ARMA) phase noise are proposed in
the paper. The state space of the ARMA model being multidimensional, the
problem cannot be approached by the conventional trellis-based methods that
assume a first-order model for phase noise and quantization of the phase space,
because the number of state of the trellis would be enormous. The proposed
lower and upper bounds are based on particle filtering and Kalman filtering.
Simulation results show that the upper and lower bounds are so close to each
other that we can claim of having numerically computed the actual information
rate of the multiplicative ARMA phase noise channel, at least in the cases
studied in the paper. Moreover, the lower bound, which is virtually
capacity-achieving, is obtained by demodulation of the incoming signal based on
a Kalman filter aided by past data. Thus we can claim of having found the
virtually optimal demodulator for the multiplicative phase noise channel, at
least for the cases considered in the paper.Comment: 5 pages, 2 figures. Accepted for presentation at ISIT 201
Verifying the Interplay of Authorization Policies and Workflow in Service-Oriented Architectures (Full version)
A widespread design approach in distributed applications based on the
service-oriented paradigm, such as web-services, consists of clearly separating
the enforcement of authorization policies and the workflow of the applications,
so that the interplay between the policy level and the workflow level is
abstracted away. While such an approach is attractive because it is quite
simple and permits one to reason about crucial properties of the policies under
consideration, it does not provide the right level of abstraction to specify
and reason about the way the workflow may interfere with the policies, and vice
versa. For example, the creation of a certificate as a side effect of a
workflow operation may enable a policy rule to fire and grant access to a
certain resource; without executing the operation, the policy rule should
remain inactive. Similarly, policy queries may be used as guards for workflow
transitions.
In this paper, we present a two-level formal verification framework to
overcome these problems and formally reason about the interplay of
authorization policies and workflow in service-oriented architectures. This
allows us to define and investigate some verification problems for SO
applications and give sufficient conditions for their decidability.Comment: 16 pages, 4 figures, full version of paper at Symposium on Secure
Computing (SecureCom09
A formal proof of the optimal frame setting for Dynamic-Frame Aloha with known population size
In Dynamic-Frame Aloha subsequent frame lengths must be optimally chosen to
maximize throughput. When the initial population size is known,
numerical evaluations show that the maximum efficiency is achieved by setting
the frame length equal to the backlog size at each subsequent frame; however,
at best of our knowledge, a formal proof of this result is still missing, and
is provided here. As byproduct, we also prove that the asymptotical efficiency
in the optimal case is , provide upper and lower bounds for the length
of the entire transmission period and show that its asymptotical behaviour is
, with .Comment: 22 pages, submitted to IEEE Trans. on Information Theor
Computing the information rate of discrete-time Wiener phase noise channels by parametric Bayesian tracking
A new upper bound (UB) on the information rate (IR) transferred through the additive white Gaussian noise channel affected by Wiener\&\#x02019;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
Optimal filtering in pilot-aided carrier recovery
The paper deals with carrier recovery based on pilot symbols in single-carrier systems. Wiener's method is used to determine the optimal unconstrained filter in estimation of phase noise assuming that a sequence of equally spaced pilot symbols is available. Our analysis allows to capture two effects that are not considered in the existing literature: the impact of aliasing due to sampling of the phase noise sequence at the pilot rate and the cyclostationary nature of the estimate hence of its performance. Experimental results are derived also for the case, where the filter is constrained to the cascade of two moving averages. These results show that, in the considered example, the mean-square phase error of the constrained filter is within 0.35 dB from the MSE of the optimal filter
- …