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.

Efficient encoding of control signaling for communication systems with scheduling and link

Abstract: The invention relates to a method of sending control information from a first node to a second node in a communications system providing a plurality of resource units for the transmission of data. The control information is sent by use of a code book comprising at least one code word identifying control information relating to data transmission over a resource unit. The code book is dynamically updated by means of repeatedly transmitting an updated version of code book information from the first node to the second node. The invention also relates to a first communications node comprising means for transmitting control information to a second node. The means for transmitting control information is adapted to transmitting the control information by use of a code book; and to repeatedly transmitting an updated version of code book information in order to achieve that the code book is dynamic.

Chapter 14 – Access Procedures

Abstract: Publisher Summary This chapter describes the procedures necessary for a terminal to be able to access an LTE-based network. Before an LTE terminal can communicate with an LTE network, it has to find and acquire synchronization to a cell within the network; and receive and decode the information, also referred to as the cell system information, needed to communicate with and operate properly within the cell. The first of these steps, simply referred to as cell search, includes acquisition of frequency and symbol synchronization to a cell; acquisition of frame timing of the cell; and determination of the physical-layer cell identity of the cell. There are 504 different physical-layer cell identities defined for LTE, where each cell identity corresponds to one specific downlink reference-signal sequence. The set of physical-layer cell identities is further divided into 168 cell-identity groups, with three cell identities within each group. This chapter begins with an overview of LTE cell search, PSS structure and SSS structure. The chapter then discusses the basic concepts of MIB and BCH transmission and system-information blocks. The chapter concludes with a discussion on terminal identification, contention resolution, and paging.

Selecting antennas in downlink cooperative scheduling

Abstract: It is presented a method for obtaining a set of selected antennas in a mobile communication network, wherein each one of the selected antennas is intended to be used in data transmissions to a first mobile communication terminal. The method is performed in a network node of the mobile communication network and comprises candidate the steps of: obtaining a set of candidate antennas, wherein each one of the candidate antennas is arranged to send out the same cell identifier and at least some of the candidate antennas have different coverage areas; evaluating performance of at least a subset of the candidate antennas in relation to the first mobile communication terminal; and determining a set of selected antennas based on the performance of the candidate performance antennas having been evaluated. A corresponding network node, computer program and computer program product are also presented.

Coded asynchronous near-far resistant DS-CDMA receivers operating without synchronization

Abstract: in this paper, several receivers for data demodulation in an asynchronous direct-sequence code-division multiple access (DS-CDMA) system operating without prior knowledge of the propagation delays are proposed and compared. Special attention is paid to the near-far problem, and the proposed schemes are numerically shown to be near-far robust. The near-far robustness is obtained by estimating the a priori unknown propagation delay using a subspace-based technique. Quantities obtained in the estimation procedure are subsequently used to design an interference suppression filter according to the minimum mean-squared error criterion. A simple two-state Viterbi algorithm is used for the data demodulation in the uncoded case. By extending the trellis used in the Viterbi algorithm, error correcting coding is easily implemented.

Random access method for multiple numerology operation

Abstract: The present disclosure introduces methods and apparatus for configuring or preconfiguring random access procedures when there are multiple configurable numerologies for one carrier. In some embodiments, the random access numerology of the wireless device is configured using the system information block. In other embodiments, the random access numerology used by the wireless device is determined implicitly based on the detection of one or more synchronization signals.

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. >