Browsing by Author "Barletta, Luca"

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A General Framework for MIMO Receivers with Low-Resolution Quantization
(2017-01-01)
Rini, Stefano
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Barletta, Luca
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Eldar, Yonina C.
;
Erkip, Elza
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交大名義發表
The capacity of a discrete-time, multi-input multioutput (MIMO) channel with output quantization is investigated for different receiver architectures. A general framework for low-resolution quantization is proposed in which the antenna outputs are processed by analog combiners and sign quantizers are used for analog-to-digital conversion. The configuration of the analog combiners is chosen as a function of the channel realization so that the transmission rate can be maximized over the set of available configurations. To exemplify the proposed approach, four analog receiver architectures are considered: (a) sign quantization of the antenna outputs, (b) single antenna selection, (c) multiple antenna selection, and (d) linear processing of the antenna outputs. In each scenario, capacity is investigated as a function of the transmit power, the number of transmit/receive antennas and sign quantizers. In particular, it is shown that architecture (a) is sufficient to approach the optimal high signal-to-noise ratio (SNR) performance for a MIMO receiver in which the number of receive antennas is larger than the number of sign quantizers. Numerical evaluations of the average performance are presented for the case in which the channel gains are i.i.d. Gaussian distributed.
Capacity of Discrete-Time Wiener Phase Noise Channels to Within a Constant Gap
(2017-01-01)
Barletta, Luca
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Rini, Stefano
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交大名義發表
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National Chiao Tung University
The capacity of the discrete-time channel affected by both additive Gaussian noise and Wiener phase noise is studied. Novel inner and outer bounds are presented, which differ of at most 7.36 bit-per-channel-use for all channel parameters. The capacity of this model can be subdivided in three regimes: (i) for large values of the frequency noise variance, the channel behaves similarly to a channel with circularly uniform iid phase noise; (ii) when the frequency noise variance is small, the effect of the additive noise dominates over that of the phase noise, while (iii) for intermediate values of the frequency noise variance, the transmission rate over the phase modulation channel has to be reduced due to the presence of phase noise.
Capacity Outer Bound and Degrees of Freedom of Wiener Phase Noise Channels with Oversampling
(2017-01-01)
Barletta, Luca
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Rini, Stefano
;
交大名義發表
;
National Chiao Tung University
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 P as P-alpha. 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 1/4.
On MIMO Channel Capacity with Output Quantization Constraints
(2018-01-01)
Khalili, Abbas
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Rini, Stefano
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Barletta, Luca
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Erkip, Elza
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Eldar, Yonina C.
The capacity of a Multiple-Input Multiple-Output (MIMO) channel in which the antenna outputs are processed by an analog linear combining network and quantized by a set of threshold quantizers is studied. The linear combining weights and quantization thresholds are selected from a set of possible configurations as a function of the channel matrix. The possible configurations of the combining network model specific analog receiver architectures, such as single antenna selection, sign quantization of the antenna outputs or linear processing of the outputs. An interesting connection between the capacity of this channel and a constrained sphere packing problem in which unit spheres are packed in a hyperplane arrangement is shown. From a high-level perspective, this follows from the fact that each threshold quantizer can be viewed as a hyperplane partitioning the transmitter signal space. Accordingly, the output of the set of quantizers corresponds to the possible regions induced by the hyperplane arrangement corresponding to the channel realization and receiver configuration. This connection provides a number of important insights into the design of quantization architectures for MIMO receivers; for instance, it shows that for a given number of quantizers, choosing configurations which induce a larger number of partitions can lead to higher rates.
On the Degrees of Freedom of the Oversampled Wiener Phase Noise Channel
(2019-01-01)
Barletta, Luca
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Rini, Stefano
;
交大名義發表
;
National Chiao Tung University
The discrete-time Wiener phase noise channel with an integrate-and-dump multi-sample receiver, referred to as the Oversampled Wiener Phase Noise (OWPN) channel is studied. The capacity of this channel is characterized by three parameters: transmit power P, oversampling factor L, and the variance of the Wiener phase noise sigma(2). The capacity of this model is connected to the capacity of two related models: the Oversampled Non-Coherent (ONC) channel and the Additive White Gaussian Noise (AWGN) channel. More precisely, it is shown that (i) the capacity of the OWPN is close to the ONC channel when sigma(2) > L while (ii) the capacity of the OWPN is close to that of the AWGN channel when sigma(2) < P-1.
The Degrees of Freedom of the Oversampled Non-Coherent Channel
(2018-01-01)
Barletta, Luca
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Rini, Stefano
;
交大名義發表
;
National Chiao Tung University
The degrees of freedom of a class of discrete-time non-coherent channels with oversampling, termed the Oversampled Non-Coherent (ONC) channel, are shown. The ONC channel is obtained from the classic continuous-time AWGN channel by considering the scenario in which the channel output is also corrupted by phase noise (PN) and processed by a multi-sample receiver. The continuous-time PN process has high variability which results in receiver output samples affected by a discrete-time PN process iid uniformly distributed over the unit circle. The ONC channel models the non-coherent detection scenario in which oversampling is employed for phase recovery but the PN process has such a high variance that its samples appear independent and uniformly distributed despite the oversampling. As such, the assumption of independent and uniformly distributed discrete PN is a limiting assumption that, generally speaking, well approximates the scenario in which the PN coherence time is much smaller than the oversampling time. In this paper, we obtain the generalized degrees of freedom for the case in which the oversampling factor L grows with the transmit power P as P-alpha. Perhaps surprisingly, we show that no degree of freedom for reliable information transfer is available for L > P-2. We conjecture that the same capacity asymptotic holds for other PN channels with oversampling, such as the oversampled Wiener PN channel, when the noise variance grows to infinity faster than the sampling rate.