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.

Prefixing of OFDM symbols to support variable subframe length

Abstract: The present disclosure relates to a first radio node configured for orthogonal frequency division multiplexing (OFDM), comprising a receiver, a transmitter, a processor and a memory storing instructions executable by the processor for causing the transmitter in a first mode of operation with a first subcarrier spacing f1: to transmit a sequence of prefixed OFDM symbols, and in a second mode of operation with a second subcarrier spacing f2: to transmit a sequence of prefixed OFDM symbols, wherein the sequence of transmitted OFDM symbols is aligned with a predefined repeating radio frame, which is common to both the first and second modes of operation, or with an integer multiple of the predefined repeating radio frame; and the first and second subcarrier spacings are related by an integer factor, f1/f2=p or f1/f2=1/p, with p≠1 integer.

User equipment and method of controlling uplink transmission power

Abstract: FIELD: wireless communicationSUBSTANCE: invention relates to radio communication UE and a method for uplink power control are provided Method comprises receiving, through signalling a configuration indicating at least one reference signal, RS, and a reference transmission power level for each indicated RS Method further comprises measuring received power of indicated at least one RS, and for each measured received power, determining a pathloss, PL, based on measured received power and reference transmission power level for each measured received power Method further comprises determining (840) an uplink transmission power based on at least one determined PLEFFECT: reduced interference18 cl, 13 dwg

Radio resource allocation of unlicensed frequency bands based on utilization rate of primary and secondary channels on one of the sharing technologies

Abstract: A method of a network node is disclosed. The network node is adapted to operate in accordance with a first radio access technology for allocation of radio resources of a frequency band (e.g. an unlicensed frequency band) to communication in accordance with the first radio access technology, wherein communication according to a second radio access technology may occupy one or more of the radio resources of the frequency band. The method comprises receiving a beacon signal associated with the second radio access technology and determining whether or not the beacon signal comprises information indicative of which of the radio resources of the frequency band are used as primary and secondary channels, respectively, in accordance with the second radio access technology. The method also comprises determining a communication activity rate of at least one of the radio resources of the frequency band. The method also comprises selecting one or more of the radio resources of the frequency band based on the determined communication activity rate (wherein, if the beacon signal comprises information indicative of which of the radio resources of the frequency band are used as primary and secondary channels, the selection is further based on the information), and allocating one or more of the selected radio resources to communication in accordance with the first radio access technology. Corresponding scheduler, network node and computer program product are also disclosed.

Numerology-dependent downlink control channel mapping

Abstract: A user equipment performs a method comprising: receiving (S110) system information indicating a current numerology of a control region with configurable numerology; and decoding (S120) the control region in accordance with an assumption of a channel mapping which is selected from at least two predefined channel mappings on the basis of the current numerology. A base station performs a method comprising: transmitting (S210) system information indicating a current numerology of a control region with configurable numerology; generating (S220) a signal using a channel mapping selected from at least two predefined channel mappings; and transmitting (S230) the generated signal in the control region, wherein the channel mapping is selected on the basis of the current numerology of the control region or vice versa.

Chapter 3 – OFDM Transmission

Abstract: Publisher Summary This chapter provides a detailed overview of orthogonal frequency-division multiplexing (OFDM). OFDM is the transmission scheme used for 3GPP LTE and is also used for several other radio-access technologies. Transmission by means of OFDM can be seen as a kind of multicarrier transmission. The basic characteristics of OFDM transmission, which distinguish it from a straightforward multicarrier extension of a more narrowband transmission scheme is the use of a typically very large number of relatively narrowband subcarriers. In contrast, a straightforward multicarrier extension typically consists of only a few subcarriers, each with a relatively wide bandwidth. The number of OFDM subcarriers can range from less than hundred to several thousand, with the subcarrier spacing ranging from several hundred kHz down to a few kHz. The subcarrier spacing used depends on types of environments the system is to operate in, including aspects such as the maximum expected radio-channel frequency selectivity (maximum expected time dispersion) and the maximum expected rate of channel variations (maximum expected Doppler spread). Once the subcarrier spacing has been selected, the number of subcarriers can be decided based on the assumed overall transmission bandwidth, taking into account acceptable out-of-band emission, and other factors.

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. >