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.

Predictive acknowledgment feedback mechanism

Abstract: A method implemented in a first communication node ( 110 ) for communicating with a second communication node ( 120 ) over an acknowledged connection ( 131 ), comprising: receiving a stream of code blocks from the second communication node, wherein each code block is associated with a check value enabling error detection and belongs to a predefined group of code blocks; detecting errors in received code blocks using respective associated check values; and transmitting to the second communication node an acknowledgement in respect of each of said predefined groups of code blocks, wherein a negative value of the acknowledgment signifies that an error was detected for at least one of the code blocks in the predefined group, wherein the acknowledgement for a predefined group of two or more code blocks is based on a combination of error detection results for a subset of the code blocks in the predefined group.

Method for power ramping in a telecommunication system

Abstract: The present invention aims to solve the problem that the preamble ramping process on a random access channel (RACH) of a 3rd generation telecommunication network can take a considerable time and, as a consequence, cause significant delays in RRC signalling and user data transmission on RACH. The present invention suggests to base the calculation of the initial preamble power value on the last performed RACH transmission instead of calculating the initial preamble power from the information that is broadcasted in the system information. This results in fewer preamble rampings until the preamble is detected in the Node-B.

The Fundamentals for Mobile Broadband, HSPA Evolution

Abstract: This book is essential reading for those wishing to obtain a systems perspective and a broad view on the background, performance and application of the latest developments in HSPA in the context of the demands on todays mobile broadband devices and networks. It takes the reader behind the scenes of 3GPP and provides an easily accessible understanding of the basic principles, the latest steps in the standards evolution, and the motivations behind the development of standardized features. It covers important topics such as smartphone related features, multi-carrier and multi-antenna operation, interface architecture, heterogeneous networks and HSPA system performance. Offering full coverage of recent developments in HSPA up to Release 13, this book will provide a comprehensive description of one of the dominating standards for mobile broadband.

Data block size management in a communication system utilizing hybrid automatic repeat requests with soft combining

Abstract: A first transceiver that supports hybrid Automatic Repeat Request (hybrid ARQ) functionality is operated. Initially, it is operated to transmit data blocks having a nominal maximum data block size. Mo. In response to detecting that a second transceiver does not have sufficient soft buffer memory space to store data blocks associated with an anticipated number of active hybrid ARQ processes, the transceiver is operated to transmit data blocks having a reduced data block size, M'. The anticipated number of active hybrid ARQ processes can be, for example, higher than a nominal number of active hybrid ARQ processes.

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. >