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.

Improved use of subframes in a cellular communications system

Abstract: The invention discloses a method (500) for a cellular communications system (100), in which traffic is sent in frames (200), each frame comprising a first number of subframes (201-210), with a second number of said subframes being available for at least either uplink or downlink traffic. At least one of said second number of subframes is made to comprise at least three parts (515), as follows: .cndot. One part (520) which is utilized for uplink traffic, .cndot. One part (525) which is utilized for downlink traffic, .cndot. One part (530) which is utilized as a guard period, with said guard period part (525) being scheduled between the uplink and the downlink parts. The duration of at least two of said three parts (520, 525, 530) may be varied to fit the current system need.

Interference Randomization of Control Channel Elements

Abstract: A method and a radio base station for interleaving control channel data to be transmitted in a telecommunications system are described. The method comprises grouping the control channel elements CCE1-CCEn into a first order of control channel symbol groups, adding symbol groups comprising dummy values or zeros to the first order of control channel symbol groups based on a number of available symbol group positions for the shared control channel, interleaving the first order of the control channel symbol groups resulting in an a second order, and mapping the second order of control channel symbol groups to the available control channel transmission resources.

TD-LTE — The radio-access solution for IMT-Advanced/TDD

Abstract: This paper provides a discussion on the LTE radio-access technology as defined in 3GPP, with specific focus on its TDD component (TD-LTE). Some specific characteristics of TDD, such as interference between uplink and downlink as well as channel reciprocity, are outlined. A discussion on possible evolution paths for the TD-LTE radio-access technology is also presented. Finally, an overview of the performance and capabilities of TD-LTE, in relation to the requirements on IMT-Advanced, is provided.

Methods and Apparatus in a Wireless Communication System for Transmitting and Receiving User Data On a Non-Legacy Carrier

Abstract: A base station (20A) is configured to transmit user data to a wireless device (16A) upon a first carrier (22). The base station (20A) identifies, from a set of transmission resources that is nominally allocated for transmission of user data upon the first carrier (22), a subset of transmission resources that is also nominally allocated for transmission of a reference or control signal either by the base station (20A) upon a second carrier (24) or by a neighboring base station (20B) upon the first carrier (22). The base station (20A) selectively transmits user data to the wireless device (16A) upon the first carrier (22) exclusive of this identified subset of transmission resources. The device (16A) in some embodiments obtains information indicating that the base station (20A) is selectively transmitting user data upon the first carrier (22) exclusive of the subset in this way. Based on this information, the device (16A) recovers user data received upon the first carrier (22) exclusive of the subset of transmission resources.

Technique for transmitting on multiple frequency resources in a telecommunication system

Abstract: The present disclosure relates to a technique for transmitting modulation symbols on multiple frequency resources. A method aspect of this technique includes applying a Discrete Fourier Transform (DFT) coding per set of modulation symbols of two or more sets of modulation symbols, wherein a first set of modulation symbols from the two or more sets of modulation symbols is transmitted on a set of frequency resources handled by the same power amplifier. Then, Orthogonal Frequency Division Multiplexing (OFDM) modulation is applied to the sets of DFT coded modulation symbols to output a first set of OFDM symbols for transmission on the set of frequency resources, and output another set of OFDM symbols for transmission on at least one additional frequency resource distinct from the set of frequency resources. Power amplification is then applied per set of frequency resources at the power amplifier.

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. >