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.

Dynamical search space alterations

Abstract: There is disclosed a method performed by a wireless device for updating an allocated search space for downlink control information. A corresponding wireless device is also disclosed. There is also disclosed a method performed by a radio network node to enable a wireless device served by the radio network node to perform an update of a search space allocated to the wireless device to monitor for downlink control information. Also provided is a corresponding radio network node. Corresponding computer programs and apparatuses are also disclosed. One particular advantage of the disclosed is that it enables a more tailor made search space for a wireless device.

Methods and Apparatuses for Enabling a Wireless Device to Communicate with a Radio Network Node in an Unlicensed Spectrum

Abstract: It is disclosed a wireless device ( 302, 90, 100 ), a radio network node ( 304, 70, 80 ) and methods therefore, for communicating in a network. The wireless device is configured to determine ( 52, 306 ) one or more possible first sequences of a discovery signal. The wireless device is configured to receive ( 54, 310 ) a second sequence of the discovery signal, and to determine ( 56, 312 ) if the one or more possible first sequences match the second sequence.

Method and apparatus for configuring sounding signals in a wireless communication network

Abstract: The teachings presented herein propose a separation between the configuration of a sounding signal, and the initialization of the sounding signal. In other words, in at least one example embodiment proposed herein, a base station or other controlling entity separates the selection of sounding signal parameters (sounding signal configuration) and the signaling of that configuration information to a mobile terminal from the Ordering” or other initiation of sounding signal transmission. Thus, a mobile station may be sent sounding signal configuration information and subsequently be commanded (implicitly or explicitly) to begin sounding signal transmissions according to the previously provided configuration information.

Method and an arrangement for avoiding unnecessary retransmissions

Abstract: A method and an arrangement for avoiding unnecessary retransmissions in a packet-based radio-communication network by exchanging transmission state information between retransmission functionality entities (12, 21) located at respective protocol layers in different network nodes (1, 2), and performing inter-layer coordination of retransmissions between the network nodes (1, 2) based on the exchanged transmission state information to provide a more efficient overall scheme for retransmissions.

Methods and apparatuses for resource allocation for random access in wireless telecommunication systems with carrier-aggregation

Abstract: The embodiments of the present invention relate to apparatuses and methods for resource allocation for random access in wireless telecommunication systems with carrier-aggregation wherein a plurality of component carriers (CCs) is defined per cell. According to a method for use in an apparatus corresponding to a radio base station (31), a message is assembled comprising information on the structure of the cell served by the radio base station; the information including one or more CCs used in the cell that is/are available for a user equipment for performing initial access in the cell. The method also comprises, transmitting the assembled message to the user equipment (30) and indicating to the user equipment which resources to use for random access in the cell. The exemplary embodiments of the present invention also relates to a method in the user equipment, to a radio base station and to a user equipment.

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. >