David Hammarwall

Bio: David Hammarwall is an academic researcher from Ericsson. The author has contributed to research in topics: User equipment & Telecommunications link. The author has an hindex of 20, co-authored 66 publications receiving 1190 citations.

Methods and arrangements for csi reporting

Abstract: Some embodiments provide a method in a wireless device for reporting channel state information, CSI, for a CSI process. The CSI process corresponds to a reference signal resource and an interference measurement resource. According to the method, the wireless device obtains (810) an adjustment value associated with the CSI process. The wireless device estimates (820) an effective channel based on one or more reference signals received in the reference signal resource, and applies (830) the adjustment value to the estimated effective channel, thereby obtaining an adjusted effective channel. Furthermore, the wireless device determines (840) channel state information based on the adjusted effective channel, and on interference estimated based on the interference measurement resource. Finally, the channel state information is transmitted (850) to a network node.

Open loop precoder cycling in mimo communications

Abstract: Data is transmitted over multiple input multiple output (MIMO) channels. Plural bit streams are modulated into multiple data symbol vectors. Each vector has a transmission rank with one vector for each MIMO channel. Transmission rank is the number of elements in a data symbol vector corresponding to the number of data streams being transmitted in parallel over each MIMO channel. The multiple data symbol vectors are preceded into multiple precoded symbol vectors using a plurality of precoder cycling sets, one set for each transmission rank including multiple different precoders. The precoders in each precoder cycling set are well-separated with respect to a plurality of distance measures. The precoding includes precoding each data symbol vector of a transmission rank with a precoder belonging to the precoder cycling set of that transmission rank. The precoded symbol vectors are then transmitted over the MIMO channels.

Evolution of uplink MIMO for LTE-advanced

Abstract: The evolution of LTE uplink transmission toward MIMO has recently been agreed in 3GPP, including the support of up to four-layer transmission using precoded spatial multiplexing as well as transmit diversity techniques. In this article, an overview of these uplink MIMO schemes is presented, along with their impact on reference signals and DL control signaling. Receivers suitable for uplink MIMO are presented, and their link performances are compared.

Parameterized Codebook Subsets for use with Precoding MIMO Transmissions

Abstract: One aspect of the teachings presented herein provides advantages for sending precoder selection feedback from a transceiver to another transceiver, for use by the other transceiver as precoding recommendations The transceiver generates two types of precoder selection feedback, where one type uses a smaller signaling payload than the other and therefore provides a distinct reduction in the signaling overhead associated with reporting precoding recommendations The transceiver uses the reduced-overhead type of reporting when reporting at certain times, or on certain channels, or in response to control signaling In one example, a UE in an LTE network sends precoder information to an eNodeB on the PUCCH by sending smaller-range index values that index only a subset of precoders, but sends full-range index values when reporting on the PUSCH, which index a larger set of precoders

Node and method for generating beamformed for downlink communications

Abstract: Example embodiments presented herein are directed towards an eNodeB, and method therein, for generating downlink communications in a multiple antenna system. The method comprises transmitting, to a number of user equipments, a plurality of reference signals, where each signal is beamformed in a distinct direction within at least one correlated domain (e.g., elevation and/or azimuth). The eNodeB receives at least one CSI report from a specific user equipment and determines a primary reference signal based on, for example, the at least one CSI report. The eNodeB may thereafter generate downlink communication signals for antenna element(s) and/or subelements of the multiple antenna system. The downlink communication signals are beamformed into a transmitting direction that aligns most closely with a beamforming direction of the at least one primary reference signal, as compared to any other beamforming direction of the reference signals.

User terminal, radio base station and radio communication method

Abstract: The present invention is designed to provide a user terminal, a radio base station and a radio communication method of novel structures that can achieve a good communication environment. A radio base station non-orthogonal-multiplexes downlink signals for a plurality of user terminals over a given radio resource, a user terminal having received the downlink signals for the plurality of user terminals decodes downlink signal for another user terminal, judges whether or not the downlink signal for the other user terminal has been successfully received, based on the decoding result of the downlink signal, reports a judgement result as to whether or not the downlink signal for the other user terminal has been successfully received and a judgement result as to whether or not a downlink signal for the user terminal has been successfully received, to the radio base station, and then the radio base station executes retransmission control of downlink signals based on reports from the user terminal.

Terminal device, base station device, communication method, and integrated circuit

Abstract: According to the present invention, there are provided a base station device, a terminal device, a communication method, and an integrated circuit capable of performing communication more efficiently when the terminal device transmits an uplink signal based on scheduling by the base station device. The terminal device includes a setting unit that sets a first uplink-downlink configuration, a second uplink-downlink configuration, and a third uplink-downlink configuration, a reception unit that monitors a physical downlink control channel accompanied with a downlink control information format which is used to schedule a physical downlink shared channel in a downlink subframe based on the third uplink-downlink configuration and includes information making a request for transmitting a sounding reference signal, and a transmission unit that transmits or drops the sounding reference signal and transmit an HARQ-ACK for transmission with the physical downlink shared channel.

User terminal, wireless base station, and wireless communication method

Abstract: In order that a user terminal properly identifies a connection cell in a radio communication system (LTE-U) for operating LTE in an unlicensed band, a user terminal for communicating with a radio base station in an unlicensed band is provided with a detection section that detects a synchronization signal transmitted from a radio base station using a dummy cell ID used in common among a plurality of radio base stations, an estimation section that performs channel estimation using a reference signal, and a reception processing section that performs reception processing of system information transmitted from a radio base station using a channel estimation result.

Method for transmitting data in multiple antenna system

Abstract: A method of transmitting data in a wireless communication system comprises receiving feedback data on an uplink data channel, the feedback data comprising a precoding matrix indicator (PMI), wherein the value of the PMI corresponds to an index in a codebook, transmitting a precoding scheme for downlink data on a downlink control channel, wherein the precoding scheme is determined as one of at least two of a transmit diversity irrespective of the received PMI, an acknowledgement indicating precoding according to the received PMI and a new PMI indicating that it is used in precoding downlink data to be transmitted, and transmitting the downlink data on a downlink data channel after applying precoding according to the determined precoding scheme