The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In this paper, the estimation of a narrowband time-varying channel under the practical assumptions of finite block length and finite transmission bandwidth is investigated. It is shown that the signal, after passing through a time-varying narrowband channel reveals a particular parametric low-rank structure that can be represented as a bilinear form. To estimate the channel, we propose two structured...
In this paper1 we consider the Network MIMO channel under the so-called Distributed Channel State Information at the Transmitters (D-CSIT) configuration where the precoder is designed in a distributed manner at each Transmitter (TX) on the basis of local versions of Channel State information (CSI) of various quality. In that setting, a novel transmission scheme has been developed in [1] and surprisingly...
A non-orthogonal multiple access (NOMA) technique is presented where the information bits of a user are carried by the least significant bits (LSBs) of other users' symbols. It is shown that the user performance can be improved by a receiver combining that relies on the alignment of sub-constellation corresponding to the LSBs at user receiver. The rate outage analysis shows that the proposed technique...
This paper studies global channel state information (CSI) in time-slotted wireless ring networks with time-varying reciprocal channels. Lower bounds on maximum and average staleness of global CSI are derived, and efficient protocols that achieve the bounds are developed. Two extreme scenarios are considered with either (i) one node transmitting at a time or (ii) the maximum number of nodes transmitting...
Massive MIMO-systems have received considerable attention in recent years as an enabler in future wireless communication systems. As the idea is based on having a large number of antennas at the base station it is important to have both a scalable and distributed realization of such a system to ease deployment. Most work so far have focused on the theoretical aspects although a few demonstrators have...
Massive multiple-input multiple-output (MIMO) systems are one of key technologies for next generation cellular providing high spectral efficiency. While the effect of most interference and noise vanishes as the number of antennas increases, performance of massive MIMO systems is limited by pilot contamination caused by correlated pilot. Pilot reuse, allowing users in distant cells to use the same...
The challenges with full-duplex (FD) transceiver implementation and transmission in small area radio communication systems are considered. The main challenge in the FD transceiver design is the self-interference (SI). Analog and digital SI cancellation is used for SI mitigation. Analog SI isolation is performed at radio frequency (RF) by utilizing an antenna design based on the characteristic modes...
This work investigates the impact of imperfect statistical information in the uplink of massive MIMO systems. In particular, we first show why covariance information is needed and then propose two schemes for covariance matrix estimation. A lower bound on the spectral efficiency (SE) of any combining scheme is derived, under imperfect covariance knowledge, and a closed-form expression is computed...
We consider a multi-cell massive MIMO system in which every base station is equipped with an array with M ≫ 1 antennas and serves a collection of users inside its cell. We study a scenario in which the base station and the users use OFDM signaling, and the channel state information (CSI) is estimated under time division duplexing (TDD) via orthogonal pilots transmitted from the users in the uplink...
Authentication on the physical layer is proposed to enhance the security of communication. Some authentication techniques assume high signal-to-noise ratio (SNR) to estimate and exploit the phase of the received signal for the hypothesis test. We study the performance of a generalized likelihood ratio test (GLRT) assuming that the phase of the received signal cannot be measured accurately. Thus the...
There has been growing interest in millimeter wave (mmWave) multiple-input multiple-output (MIMO) systems, which would likely employ hybrid analog-digital precoding with large-scale analog arrays deployed at wide bandwidths. Primary challenges here are how to efficiently estimate the large-dimensional frequency-selective channels and customize the wideband hybrid analog-digital precoders and combiners...
In this work we characterize all ambiguities of the convolution on two fixed finite-dimensional complex vector spaces. It will be shown that the convolution ambiguities correspond to factorization ambiguities in the z-domain, which are generated by swapping their zeros. We use this polynomial description to show a deterministic version of a recently introduced masked Fourier phase retrieval design...
This work studies the average probability of error for randomized space-time codes (RSTCs) when channel state information (CSI) is not perfect. We show that the diversity order of RSTC using the maximum-likelihood channel estimation and the mismatched receiver is the same as that of RSTC with perfect CSI. However, the coding gain is affected by a factor which decreases to 1 as the number of pilot...
Spectrum pooling is not typically used in current cellular networks, because it only provides a slight performance improvement while requiring heavy coordination among different cellular operators. However, these problems can be potentially overcome in millimeter-wave (mmWave) networks, thanks to the use of beamforming both at base stations and at user equipments. In this paper, we develop a joint...
This paper considers distributed massive MIMO networks where a large number of antennas, either collocated or geographically scattered over a region, communicate with mobile users. This communication is impaired by interference from similar transmissions in adjacent regions and by noise. Focusing on zero-forcing (ZF) reception, we derive simple expressions that very accurately approximate the instantaneous...
A required feature for the next generation of wireless communication networks will be the capability to serve simultaneously a large number of devices with heterogeneous CSIT qualities and demands. In this paper, we consider the overloaded MISO BC with two groups of CSIT qualities. We propose a transmission scheme where degraded symbols are superimposed on top of spatially-multiplexed symbols. The...
The estimation of the Ricean K factor in case of noisy complex channel coefficients is addressed. A new deterministic estimator is designed, and the relevant deterministic Cramer-Rao Lower Bound (CRLB) is derived. It is shown by simulation that the new estimator outperforms the existing ones in term of both bias and Normalized Mean Square Error (NMSE), and is close to the CRLB. We also design two...
Millimeter-wave (mmWave) cellular systems are a promising option for a very high data rate connectivity in near future because of the large bandwidths available at this range of frequencies. Communication at mm Waves, however, is quite challenging due to the large path-loss exponent compared with the traditional sub-6GHz counterpart. Directional beamforming with large antenna gains both at the user...
Mixed hybrid-low resolution MIMO architectures reduce both the number of ADCs and their resolution to reduce power consumption. In such a system, the received signal suffers from two compression stages. One is due to the analog processing stage and the reduced number of RF chains, while the other is a result of signal quantization by the ADC converters. The compression steps both complicate the estimation...
This paper studies a specific sequential decision making problem: joint optimization of power and communication decisions of a remote estimation problem over an additive noise channel. At each time, the sensor observes a sample from a one-dimensional stochastic process, and then decides whether to transmit its observation to the remote estimator or not, which takes place over an additive noise channel...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.