Browsing by Author "Ghabeli, Leila"

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Asymmetric Successive Compute-and-Forward
(2016)
Ghabeli, Leila
;
Derpich, Milan S.
;
電機學院
;
College of Electrical and Computer Engineering
In this paper we review the previously proposed methods for successive compute-and-forward and discuss about their incompleteness through some examples. Then we present a comprehensive formulation for multi-step successive interference cancellation problem through the asymmetric successive compute-and-forward strategy. It is shown that the generalized formulation includes the previous approaches.
On the Capacity of the Gaussian Broadcast Channel with States Known at the Transmitter
(2016)
Ghabeli, Leila
;
Rini, Stefano
;
電信工程研究所
;
Institute of Communications Engineering
This paper studies the capacity of the general Gaussian broadcast channel with states non-causally known at the transmitter. This channel is obtained from the two-user Gaussian broadcast channel by further considering the presence of an additive state sequence in each channel output. Having anti-causal knowledge of both the channel state sequences, the transmitter wishes to reliably communicate both a common and a private message to each receiver. This channel is the natural compounding of the Gaussian broadcast channel and the "writing on dirty" paper channel and it addresses the question of how the transmitter can best simultaneously pre-code its transmissions against the different state realization at the two receivers. We introduce novel inner and outer bounds and derive the approximate capacity to within 3 bits per channel use for the model with independent, Gaussian distributed channel states. This result extends a number of results previously available in the literature, thus providing a general framework to understand state pre-cancellation in multiuser settings.
The Capacity Gap Calculation for Multi-Pair Bidirectional Gaussian Relay Networks Based on Successive Compute-and-Forward Strategy
(2016)
Ghabeli, Leila
;
Derpich, Milan S.
;
電機學院
;
College of Electrical and Computer Engineering
In this work we obtain capacity gaps for a class of N -pair bidirectional Gaussian relay networks, where one relay can help communications between the corresponding user pairs. For the uplink, we apply the generalization of successive compute-andforward strategy (SCAF) for decoding the linear combinations of the messages of each user pair at the relay. The downlink channel is considered as a broadcast network with N receiver groups. It is shown that for all channel gains, the achievable rate boundary lies within gaps of (N - 1 + log(2) N)/2 N and (N + log(2) N)/2N bits/sec/Hz below the cut-set upper bound for restricted and nonrestricted models, respectively. These gaps tend to 1/2 bits/sec/Hz per user as N goes to infinity. We first derive a comprehensive formulation for the N -step asymmetric SCAF and use it to derive the capacity result for our problem.