Stefan Parkvall

Bio: Stefan Parkvall is an academic researcher from Ericsson. The author has contributed to research in topics: Telecommunications link & Node (networking). The author has an hindex of 58, co-authored 502 publications receiving 19083 citations. Previous affiliations of Stefan Parkvall include Royal Institute of Technology & University of California, San Diego.

Propagation Delay Estimation of Fading DS-CDMA Signals

Abstract: In this paper we consider the problem of estimating the propagation delays of the transmitted signals in an asynchronous direct-sequence code division multiple access (DS-CDMA) system operating over a fading channel. Two estimators based on subspace techniques are compared and the Cram er-Rao Bound, a lower bound on the variance of any unbiased estimator, is derived. Special attention is paid to the near-far problem.

Wireless communication block interleaving

Abstract: Apparatuses and methods are disclosed for block interleaving. In one embodiment, a method includes generating an interleaver sequence for a control resource set, CORESET, configuration for a physical downlink control channel, the interleaver sequence associated with an interleaving matrix; optionally, for each one of an allowed value of number of rows for the interleaving matrix, determining a number of null entries to be added to the interleaving matrix; and selecting a number of rows. R, for the interleaving matrix such that the number of null entries to be added to the interleaving matrix is: no more than a number of columns, C, of the interleaving matrix; and optionally, the smallest among the numbers of null entries determined for each of the allowed values of number of rows for the interleaving matrix. In another embodiment, a method includes decomposing the interleaver sequence.

Shortening of uplink sub-frame in time division duplex (tdd)

Abstract: PROBLEM TO BE SOLVED: To provide a method for switching between an uplink and a downlink while maintaining interference between downlink transmission and uplink transmission to be minimum and maintaining control signaling to be minimum and to provide a wireless node in a dynamic time division duplex (TDD) system.SOLUTION: A guard period for switching an uplink sub-frame and a downlink sub-frame is created by shortening the uplink sub-frame, that is, by executing no transmission during at least one symbol section on the leading edge of the sub-frame section. A grant message includes a signaling showing the timing at which the shortened sub-frame should be transmitted.SELECTED DRAWING: Figure 16

Highly reliable transmission scheme with low level of use of resources

Abstract: FIELD: radio engineering, communication.SUBSTANCE: transmitting node, a receiving node and methods of providing a highly reliable transmission scheme and efficient use of resources. The transmission scheme includes two modes, wherein the first mode comprises of a regular retransmission with acknowledgment and the second mode contains accelerated or otherwise activated retransmissions.EFFECT: increased probability of successful transmission of a message within the acceptable delay budget.35 cl, 10 dwg

Wireless device, network node and methods for reporting channel state information (csi) in radio communications network

Abstract: FIELD: radio engineering and communications.SUBSTANCE: invention relates to means for providing information on the status of a CSI channel in a radio data transmission network. Method performed by the wireless device for determining Channel State Information, CSI, estimates to be transmitted in a CSI report for at least one CSI process configured for the wireless device to a network node in a radio communications network, method comprises an order of actions: receiving a message comprising an indication to discard existing CSI estimates corresponding to a determined period of time and determining CSI estimates, which should be used in the CSI report to the network node, in accordance with the accepted indicator, in which the network node causes the wireless device to transmit CSI estimates corresponding to the CSI measurement results obtained from a single point in time.EFFECT: technical result is to improve the reporting of information on the state of the CSI channel in the radio data transmission network.24 cl, 5 dwg

Noncooperative Cellular Wireless with Unlimited Numbers of Base Station Antennas

Abstract: A cellular base station serves a multiplicity of single-antenna terminals over the same time-frequency interval. Time-division duplex operation combined with reverse-link pilots enables the base station to estimate the reciprocal forward- and reverse-link channels. The conjugate-transpose of the channel estimates are used as a linear precoder and combiner respectively on the forward and reverse links. Propagation, unknown to both terminals and base station, comprises fast fading, log-normal shadow fading, and geometric attenuation. In the limit of an infinite number of antennas a complete multi-cellular analysis, which accounts for inter-cellular interference and the overhead and errors associated with channel-state information, yields a number of mathematically exact conclusions and points to a desirable direction towards which cellular wireless could evolve. In particular the effects of uncorrelated noise and fast fading vanish, throughput and the number of terminals are independent of the size of the cells, spectral efficiency is independent of bandwidth, and the required transmitted energy per bit vanishes. The only remaining impairment is inter-cellular interference caused by re-use of the pilot sequences in other cells (pilot contamination) which does not vanish with unlimited number of antennas.

Scaling Up MIMO: Opportunities and Challenges with Very Large Arrays

Abstract: Multiple-input multiple-output (MIMO) technology is maturing and is being incorporated into emerging wireless broadband standards like long-term evolution (LTE) [1]. For example, the LTE standard allows for up to eight antenna ports at the base station. Basically, the more antennas the transmitter/receiver is equipped with, and the more degrees of freedom that the propagation channel can provide, the better the performance in terms of data rate or link reliability. More precisely, on a quasi static channel where a code word spans across only one time and frequency coherence interval, the reliability of a point-to-point MIMO link scales according to Prob(link outage) ` SNR-ntnr where nt and nr are the numbers of transmit and receive antennas, respectively, and signal-to-noise ratio is denoted by SNR. On a channel that varies rapidly as a function of time and frequency, and where circumstances permit coding across many channel coherence intervals, the achievable rate scales as min(nt, nr) log(1 + SNR). The gains in multiuser systems are even more impressive, because such systems offer the possibility to transmit simultaneously to several users and the flexibility to select what users to schedule for reception at any given point in time [2].

Two decades of array signal processing research: the parametric approach

Abstract: The quintessential goal of sensor array signal processing is the estimation of parameters by fusing temporal and spatial information, captured via sampling a wavefield with a set of judiciously placed antenna sensors. The wavefield is assumed to be generated by a finite number of emitters, and contains information about signal parameters characterizing the emitters. A review of the area of array processing is given. The focus is on parameter estimation methods, and many relevant problems are only briefly mentioned. We emphasize the relatively more recent subspace-based methods in relation to beamforming. The article consists of background material and of the basic problem formulation. Then we introduce spectral-based algorithmic solutions to the signal parameter estimation problem. We contrast these suboptimal solutions to parametric methods. Techniques derived from maximum likelihood principles as well as geometric arguments are covered. Later, a number of more specialized research topics are briefly reviewed. Then, we look at a number of real-world problems for which sensor array processing methods have been applied. We also include an example with real experimental data involving closely spaced emitters and highly correlated signals, as well as a manufacturing application example.

On the capacity of a cellular CDMA system

Abstract: It is shown that, particularly for terrestrial cellular telephony, the interference-suppression feature of CDMA (code division multiple access) can result in a many-fold increase in capacity over analog and even over competing digital techniques. A single-cell system, such as a hubbed satellite network, is addressed, and the basic expression for capacity is developed. The corresponding expressions for a multiple-cell system are derived. and the distribution on the number of users supportable per cell is determined. It is concluded that properly augmented and power-controlled multiple-cell CDMA promises a quantum increase in current cellular capacity. >