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.

Drx functionality in multi-carrier wireless networks

Abstract: Mechanisms to provide independent DRX (discontinuous reception) functionalities for individual carriers of a multi-carrier wireless network (200) are described. DRX is a higher layer functionality indicating which TTIs (transmission time intervals) a user equipment (220) needs to read for control signals. Operating in the DRX cycle allows the user equipment (220) to reduce battery consumption. A connection is established between a base station (210) and the user equipment (220) over a plurality of carriers, where for each carrier, an independent DRX cycle is established. The plurality of carriers include anchor carriers which can carry commands from the base station (210). The anchor carriers have shorter DRX cycles than the non-anchor carriers. When a large amount of download data is to be transferred, the DRX cycles of multiple carriers are overridden and used for transfer to achieve fast download rates. The override commands are sent from the base station (210) to the user equipment (220) prior to the transfer.

Arrangement and method for identifying PUCCH format 3 resources

Abstract: The disclosure relates to a user equipment for a wireless communications system, and to a related method for identifying a resource to use for a transmission of control information on a physical uplink control channel, PUCCH, format 3. The method comprises receiving (610) a resource index from a serving radio base station, and identifying (620) the resource to use for the transmission of the control information in a subframe based on the received resource index, wherein the identified resource is within a same confined set of physical resource blocks regardless of if a normal or a shortened PUCCH format 3 is used in the subframe.

Closed loop power control in a heterogeneous network by selecting among sets of accumulative power step values

Abstract: A method is provided in a wireless device for controlling output transmission power from the wireless device A set is selected among a plurality of sets of power step values, which reside in a memory of the wireless device, responsive to criteria defined in the wireless device A power control command is received from a radio network node One of the power step values of the selected set is selected responsive to the power control command The output transmission power from the wireless device is controlled responsive to the selected power step value Related methods in radio network nodes and apparatuses are disclosed

Managing energy consumption of base stations

Abstract: A base station includes an emulation controller (20) configured to receive signals indicating that another base station in an active mode managing a cell, having a predetermined cell identity and coverage area, will go into an idle mode and no longer manage the cell, and to determine terminal activity in the cell. A baseband processing unit (18) is connected to the emulation controller (20) and configured to emulate the active mode of the other base station by taking over management of the cell, in at least part of its coverage area, using the same cell identity.

Transmit diversity in WCDMA: link and system level results

Abstract: In the current WCDMA standard, support for transmit diversity is provided in the down-link to combat fading and changing interference situations. The base station (node B) is equipped with two transmit antennas, while the terminal (user equipment, UE) uses only a single antenna. This arrangement is advantageous compared to receive diversity as it removes the need for two antennas in the terminal. This paper describes the various transmit diversity schemes in WCDMA and gives simulation results, both at the link and system levels. It is found that transmit diversity can greatly improve the system capacity.

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. >