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.

Uplink power control for limited power terminals

Abstract: A method for controlling the transmission power in a mobile terminal (200) in a wireless communication system in which a transmission bandwidth allocated for transmissions by the mobile terminal (200) is variable by transmission, the method comprising receiving (310) a plurality of transmission power control orders, each transmission power control order administering an adjustment in the transmission power related to a previous transmission of the mobile terminal (200); characterized in that the method further comprises: when the mobile terminal is in a state of power limitation that requires the mobile terminal to transmit at its maximum transmission power: - adjust (350) a cumulative power control value when a control order of received transmission power administers a negative adjustment in the transmission power; - ignoring a transmission power control order received when the transmission power control order received administers a positive adjustment in transmission power, so that the accumulated power control value is not adjusted when the control order of received transmission power administers a positive adjustment in transmission power; and - calculate (360) respective transmission power settings for each transmission by the mobile terminal (200) as the lower of the maximum transmission power for the mobile terminal and the transmitter output power calculated based on the bandwidth assigned for the transmission and the accumulated power control value.

Enhancement of reception quality for an uplink control channel

Abstract: A radio network controller, RNC, 614, and a method therein, for enhancing reception quality of transmissions on an uplink control channel from a user equipment, UE, 613 to a serving base station, BS, 610. The RNC, the UE and the serving BS are comprised in a communication system 600. The method comprises, when conditions for boosting the uplink control channel are fulfilled, determining a boosting factor based on a ratio of path gains of a channel from the UE to the serving BS and of a channel from the UE to a non- serving BS 611, respectively, which non-serving BS is comprised in the communications system. The method further comprises transmitting the determined boosting factor to the UE, whereby the reception quality of transmission on the uplink control channel from the UE to the serving BS is enhanced by the UE boosting the control channel by means of the boosting factor.

Signal transmission on mutiple component carriers 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.

예측적 확인응답 피드백 메커니즘

Abstract: 확인응답식 접속(131)을 통해 제2 통신 노드(120)와 통신하기 위해 제1 통신 노드(110)에서 구현되는 방법은: 제2 통신 노드로부터 코드 블록들의 스트림을 수신하는 단계 - 각각의 코드 블록은 에러 검출을 가능하게 하는 체크 값과 연관되고, 미리 정의된 코드 블록들의 그룹에 속함 -; 각각의 연관된 체크 값들을 사용하여 수신된 코드 블록들의 에러들을 검출하는 단계; 및 상기 미리 정의된 코드 블록들의 그룹들 각각에 대한 확인응답을 제2 통신 노드로 송신하는 단계 - 확인응답의 음의 값은 미리 정의된 그룹 내의 코드 블록들 중 적어도 하나에 대해 에러가 검출되었음을 나타냄 - 를 포함하고, 미리 정의된 2개 이상의 코드 블록의 그룹에 대한 확인응답은 미리 정의된 그룹 내의 코드 블록들의 서브세트에 대한 에러 검출 결과들의 결합에 기초한다.

Channel state feedback delivery in a telecommunication system

Abstract: Channel state feedback is provided from a UE (800) to a base station (700) as a first, detailed or a second, less detailed type of channel state feedback information. Initially it is determined (403) whether the UE has received an uplink grant from the base station or not. If the UE has received an uplink grant, a first type of channel state feedback information is transmitted (404) to the base station on the granted resource. If, however, the UE has not received an uplink grant, a second type of channel state feedback information is transmitted (405) to the base station. Different types of channel state feedback information enables a UE and an associated base station to use available resources more efficiently, when requesting for and delivering channel state feedback information.

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. >