Telefonaktiebolaget Lm Ericsson (publ)

Optis Wireless Technology, LLC

Mats Åhlander

David Sandberg

Hong Ren

Chandra Sekhar Bontu

Fredrik Huss

Jianguo Long

Yongquan Qiang

Muhammad Ali Kazmi

Jung-Fu Cheng

Torbjörn Wigren

Mårten Sundberg

Laetitia Falconetti

Imadur Rahman

Ari Kangas

Oskar Mauritz

Jianwei Zhang

Anders Johansson

Tomas Lagerqvist

Magnus Hurd

Dominique Everaere

Mikael Jonsson

Stéphane Tessier

Patrik Rask

Pontus Arvidsson

Christer Aalto

Systems and methods for estimating Signal-to-Noise Ratio (SNR) for Multi-User Multiple-Input and Multiple-Output (MU-MIMO) based on channel orthogonality. In some embodiments, a method performed by a radio access node includes obtaining a SU-MIMO signal quality measurement for at least a first user and an additional user; obtaining an indication of orthogonality between a channel of the first user and a channel of the additional user; and estimating a MU-MIMO signal quality measurement for the first user as if the first user and the additional user are paired with each other for a potential MU-MIMO transmission based on the SU-MIMO signal quality measurements and the indication of orthogonality. In this way, a computational complexity for the SINR estimation of MU-MIMO users can be greatly reduced. This may enable a large number of user pairing alternatives to be evaluated in practical wireless systems to achieve improved MU-MIMO performance.

Method to estimate SNR for MU-MIMO based on channel orthogonality

A method and a network node () serving a first cell in a wireless network, for reducing interference in a second cell caused by transmission of reference signals in the first cell. The network node () transmits () in the first cell a scheduling block where a number of said reference signals are located in predefined resource element positions in the scheduling block, using a time offset relative transmission of a scheduling block in the second cell. Thereby, the impact of interference from a reference signal from one network node will be distributed over several resource elements in the other network node so that the impact in each resource element is reduced, as compared to when all interference from the reference signal hits one single resource element when no time offset is used.

Method and network node for reducing interference in a wireless network

A method in a network node for Multiple Input Multiple Output (MIMO) is provided. The method comprises: obtaining a precoding matrix indicator (PMI) for a first codebook for use in a Single User Multiple Input Multiple Output (SU-MIMO) transmission; determining a precoding matrix for a second codebook, based on the obtained precoding matrix indicator; and selecting the determined precoding matrix for the second codebook in response to determining that an User Equipment (UE) is scheduled for a Multi-User (MU)-MIMO transmission. A network node for performing this method is also provided.

Method and network node for generating and selecting a codebook in a MIMO communication network

A method in a first node () is disclosed. The method comprises determining () a time resource over which the first node transmits a signal to a second node (). The method comprises signaling (), to at least one of the second node or a third node (), information about one or more transient time parameters associated with the time resource, wherein the one or more transient time parameters are used by the first node for transmitting the signal to the second node during the time resource. The method comprises adapting () a transmitter configuration of the first node for transmitting the signal to the second node based on one of the one or more transient time parameters.

Optimizing network demodulation performances by signaling supported UE transient time

There is provided a method for managing transmission of a Cell-specific Reference Signal, CRS, comprising a plurality of reference symbols to User Equipment, UE, in a wireless communication system operating at least one cell or sector. The method comprises identifying a UE for which a beamformed transmission of data is scheduled during a transmission time interval, and enabling, during the transmission time interval, beamformed transmission of at least part of the reference symbols of the CRS for targeting the identified UE.

Managing transmission of a cell-specific reference signal

A method and a first network node () serving a first cell (A) in a wireless network, for enabling reduction of interference in a second cell (B) caused by transmission of reference signals in the first cell (A). The first network node () transmits () scheduling blocks with said reference signals, using a time offset relative transmission of scheduling blocks in the second cell. A timing advance value is determined () for a wireless device () and the wireless device () instructed () to apply said timing advance value for uplink transmissions. The timing advance value was determined such that uplink symbols transmitted from the wireless device () are aligned with uplink symbols received at a second network node () of the second cell (A).

Method and network node for enabling reduced interference in a wireless network

Embodiments of a method in a base station for precoding a downlink transmission are disclosed. In some embodiments, the method comprises obtaining, for a time instant k, an estimate of a channel matrix for a wireless channel for a downlink from the base station to a wireless device and projecting the estimate of the channel matrix onto one or more sets of spatial orthonormal functions, thereby obtaining respective sets of coefficients. The method further comprises, for each set of spatial orthonormal functions, filtering the set of coefficients for the time instant k based on a filtering parameter that is specific to a downlink channel to be transmitted. The method further comprises generating beamforming weights using the filtered set of coefficients for at least one of the sets of spatial orthonormal functions, and precoding the downlink channel using the beamforming weights.

Beamforming in cellular systems using the same feedback information for different physical channels

A scheduling function node (SF) uses the beams available for each WCD to avoid scheduling a transmission that would imply that interference between WCDs is created. In the simplest form such a scheme could be described as follows: (1) avoid scheduling transmission in directions that coincide between WCDs (here, a direction would typically be represented by both azimuth and elevation angles) and (2) when the available beam directions do not allow interference avoidance, accounting for this fact and exploiting other types of orthogonality in the scheduling of time-frequency resources.

Apparatuses, methods, computer programs, and computer program products for interference avoidance

It is presented a method for controlling cyclic shift for demodulation reference symbols for uplink communication in a cellular communication network. The method is performed in a network node and comprises the steps of: determining a first cyclic shift parameter for demodulation reference symbols based on a current subframe index; generating a control message comprising the first cyclic shift parameter; and transmitting the control message to a wireless device of the cellular communication network. Corresponding network nodes, computer program and computer program product are also presented.

Controlling cyclic shift for demodulation reference symbols

The teachings relate to a methodperformed in a network nodefor determining a link adaptation parameter, SINR, for a wireless device. The network nodesupporting a multi-antenna transmission mode comprising spatial multiplexing layers for transmission of data on a channel between the wireless deviceand the network node. The methodcomprises: determininga channel covariance matrix HH for the channel, wherein H is the channel matrix for the channel; approximatinga post-equalizer signal to interference plus noise ratio SINR., for a spatial multiplexing layer i using the channel covariance matrix HH; determiningan offset SINR, i to be the difference between a received signal to interference plus noise ratio SINRand the approximated post-equalizer signal to interference plus noise ration SINR, and determiningthe link adaptation parameter SINRto be the approximated post-equalizer signal to interference plus noise ratio SINRcompensated by the determined offset SINR. Corresponding network node, computer program and computer program products are also provided.

Methods and devices for determining link adaptation parameters

A base station that implements an improved link adaptation process that takes into account the fact that a certain reference signal (e.g., CSI-RS) may be seen as interference by certain wireless communication devices (WCDs). Accordingly, when the base station schedules a data transmission for the WCD to occur in a particular TTI and the base station is scheduled to transmit the CSI-RS during the same TTI, the base station will tend to select a more robust MCS for the data transmission to the WCD to counter effect the possible interference caused by the CSI-RS.

Methods and systems for link adaptation

A method in a base station () for providing an estimate of interference and noise power of an uplink resource block. The base station () is comprised in a cellular communications network (). The base station () receives () on multiple antenna elements (-) of a receiver antenna () a signal comprising interference and noise. The base station () calculates () an interference and noise covariance matrix for the resource block based on the received signal. The base station () then calculates () the estimate based on the calculated interference and noise covariance matrix, the number of the multiple antenna elements (-) of the receiver antenna () and a channel covariance matrix for a virtual user equipment. The provided estimate enables an interference and noise measure when Interference Rejection Combining (!RC) is applied in the uplink. Thereby more efficient use of uplink Frequency Selective Scheduling (FSS) together with uplink IRC and improved performance in the cellular communications network is enabled.

Method and base station for providing an estimate of interference and noise power of an uplink resource block

A method in a radio network node for estimating channel gain over frequencies of a bandwidth in a radio communications network. The radio network node measures a first channel gain based on a received power of a sounding reference signal over a first set of frequencies from a user equipment, which first set of frequencies is comprised in the frequencies of the bandwidth. Furthermore, the radio network node measures a second channel gain based on a received power of a received demodulation reference signal of a physical uplink shared channel over a second set of frequencies from the user equipment, which second set of frequencies is comprised in the frequencies of the bandwidth. The radio network node then estimates a third channel gain over the frequencies of the bandwidth based on the measured first channel gain and the measured second channel gain.

Channel estimation using reference signals

An LTE uplink soft demapper includes an SC-FDMA symbol noise power meter () configured to individually determine a noise power measure for each SC-FDMA symbol in a slot by exploiting information contained in modulated data symbols of the corresponding SC-FDMA symbol. A bit soft value normalizer () connected to the SC-FDMA symbol noise power meter () is configured to normalize bit soft values, representing reliability of received bits obtained from the SC-FDMA symbols in the slot, based on the determined noise power measures.

Bit soft value normalization

A basic idea is to determine (S) occurrence of a glitch caused by operation of the AGC mechanism, identify (S) those modulation symbols in a digitized version of the received signal that are affected by the glitch, each modulation symbol represented by a number of bits in combination, and then reduce (S), for each of the identified modulation symbols, the contribution in representing the identified modulation symbol as provided by at least a subset of the bits of the modulation symbol. In this way, the adverse effects of the glitch can be effectively mitigated and subsequent detection of the desired signal can be significantly improved. This also means that the link performance will be significantly improved.

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Täby, Sweden

Mats Åhlander