Telefonaktiebolaget Lm Ericsson (publ)

St-ericsson Sa

Torsten John Carlsson

Kjell Berthold Gustafsson

Magnus Nilsson

Peter Jakobsson

Martin Isberg

Torgny Palenius

Magnus Sandgren

Jan Celander

Christer Östberg

Roozbeh Atarius

Torbjörn Wigren

Bo Göransson

Karl Werner

Jonas B Karlsson

Håkan B Eriksson

Bjorn Martin Lindquist

Jing Rao

Jacob Mannerstrangle

Andres Reial

Henrik Sahlin

Henrik Bengtsson

Anders Carlsson

Dandan Hao

Magnus Tillgren

Anders Linge

Hans Hagberg

H&aring;kan Eriksson

Per Ingelhag

Magnus Hollstr&ouml;m

Christian Braun

Christer &Ouml;stberg

Peter Svensson

Sten Wallin

Joakim Plahn

Hakan B Eriksson

Leif Martin Hellmark

Lars Peter Kunkel

Agneta Ljungbro

Martin Hellmark

Ivan Medved

Sofie Wergeland

Ola Lennartsson

Lars-Peter Kunkel

Tomas Hansson

Örjan Renström

Kjell Torgil Svensson

Radio channel estimation in a radio node is provided. The radio node is configured to receive a number of wideband reference symbols corresponding to a wideband radio channel having a wideband bandwidth and convert the wideband reference symbols into a number of wideband taps each having a complex value and associated with a respective beam direction and a respective tap delay. The radio node dynamically determines a wideband power threshold based on channel information related to the wideband channel. Accordingly, the radio node determines a subset of the wideband taps based on the wideband power threshold and generates a channel estimate for the wideband radio channel based on the subset of wideband taps. As a result, the radio node may create a more accurate channel estimation across the wider channel bandwidth over a large span of SNR conditions.

Radio channel estimation in a radio node

An Advanced Antenna System (AAS) receiver and related methods are provided. According to one aspect an AAS receiver comprises a digital processing block of a Radio Frequency Integrated Circuit (RFIC). The digital processing block comprises an interface for communicating with a Central Unit (CU), and a plurality of Antenna Signal Processing Blocks (ASPBs), each receiving a digitized receive signal from a respective antenna element of an antenna array. Each ASPB comprises one or more receivers, each of which receives the signal from the respective antenna element, processes the received signal, and beamforms the processed signal to produce one or more data streams to be sent to the CU. Each ASPB also includes a narrowband receiver that processes an input signal (either the signal received from the respective antenna element or that signal after processing) to create a narrowband signal that is provided to the CU directly, without beamforming.

Versatile AAS receiver

An over the air, OTA, procedure derives a propagation delay (Formula I) of radio signals transmitted between a first radio network node (BS) and a second radio network node (BS) operative in a wireless communication system. Using this propagation delay, a two-step synchronization procedure accurately synchronizes, or time-aligns, antennas at the radio network nodes (BS, BS) for both transmission and reception. In a first step, each radio network node (BS, BS) is accurately calibrated, to obtain a total calibrated delay (Formula II) reflecting the sum of delays through a calibrated receiver path (Formula II) and a calibrated transmitter path (Formula III). In a second step, a pair of radio network nodes (BS, BS) separately align their antenna transmit and receive timings in a procedure in which a first radio network node (BS) is a master and a second radio network node (BS) is a slave.

Over the air antenna synchronization in wireless communication network

Systems and methods for efficient scheduling of Random Access Channel (RACH) occasions in a cellular communications system are provided. In one embodiment, a method performed by a base station comprises transmitting Synchronization Signal Blocks (SSBs) on respective transmit beams in accordance with a beam sweeping scheme. The SSBs are mapped to one or more RACH occasions in accordance with an N-to-1 mapping scheme where N is greater than 1. The method further comprises, for each RACH occasion, processing receive signals from at least a subset of antenna elements in an antenna array of the base station using respective narrowband receivers, thereby providing narrowband receive signals, and performing, based on the narrowband receive signals, random access preamble detection for multiple beam directions that correspond to at least a subset of the transmit beams on which at least a subset of the SSBs to which the RACH occasion is mapped were transmitted.

Efficient PRACH scheduling

In an example embodiment, a system comprises a chain of serially coupled nodes, including a central processing node (CPN) and one or more radio communications nodes (RCNs). The CPN couples to a first RCN in the chain via a dielectric waveguide (DWG) link and any further RCNs in the chain are successively connected in serial fashion from the first RCN via further (DWG) links. The CPN generates outbound radio carrier signals that are waveguide-propagated in a downstream direction of the chain, for over-the-air (OTA) by targeted ones of the RCNs, while radio carrier signals received via OTA reception by respective ones of the RCNs are waveguide propagated as inbound radio signals in an upstream direction of the chain, for processing by the CPN. Advantages from he contemplated system include greatly simplified implementation of the RCNs, with lower cost and power consumption. Further, strategic placement of failover CPNs and DWG links provide for continued operation in the face of CPN or DWG link failures.

Method and apparatus for radio communications

Disclosed is a method and a first transceiver of a wireless communication network, for handling reference signals. The method comprises receiving, from a second transceiver, at antenna elements of each of M antenna branches of the first transceiver and in time domain, an OFDM modulated wideband reference signal comprising an OFDM reference signal symbol mapped to every K subcarrier frequency of at least a subset of a carrier frequency bandwidth, and, at each of the M antenna branches, sampling the received wideband reference signal using N samples per OFDM symbol. The method further comprises, for each of the M antenna branches, accumulating the received, sampled wideband reference signal over at least two repetition blocks, each of length of N/K, to obtain a condensed signal with the length N/K samples and conveying the condensed signal over an interface to an aggregate unit.

Method and transceiver of a wireless communication network for handling reference signals

A distributed wireless system comprises controlling node and two or more antenna processing nodes communicatively coupled to the controlling node but spatially separated from each other and from the controlling node. The controlling node sends commands to and exchanges data with a first subset of the antenna processing nodes, using a first twisted-pair lane of a physical layer interface having four twisted-pair lanes, and sends commands to and exchanging data with a second subset of the antenna processing nodes, using a second twisted-pair lane. In some embodiments, the controlling node also uses a third twisted-pair lane for communicating with the first subset, while using the fourth twisted-pair lane for communicating with the second subset. Corresponding antenna processing nodes terminate one or two twisted-pair lanes in a direction towards the controlling node, while terminating one or two twisted-pair lanes towards one or more antenna processing nodes further from the controlling node.

Interface in series-connected radios

A first antenna processing node receives () one or more wireless transmissions from a wireless device and obtains first symbol values from the one or more wireless transmissions. The first antenna processing node receives () second symbol values from a second antenna processing node, the second symbol values corresponding to the one or more wireless transmissions as received at the second antenna processing node, and calculates () a first weight parameter based on at least a subset of the first symbol values and a corresponding subset of the second symbol values. The first antenna processing node calculates () third symbol values by computing a weighted sum of first symbol values and corresponding ones of the second symbol values, using the first weight parameter, and sends () the third symbol values to a third antenna processing node or to a controlling node. This combining of symbol values may approximate maximum ratio combining, MRC.

Coherent summing of signals from distributed radio access points

A wireless system comprises a controlling node and two or more antenna processing nodes coupled to the controlling node but separated from each other. The controlling node sends () a command to a first one of the two or more antenna processing nodes, instructing the first one of the two or more antenna processing nodes to transmit data to a wireless device. This may be preceded by selecting () the first one of the antenna processing nodes based on an estimated signal quality metric corresponding to the wireless device for each antenna processing node. In response to a determination by the controlling node that the wireless device has not successfully decoded the data, the controlling node sends () a command to a second one of the two or more antenna processing nodes, instructing the second one of the antenna processing nodes to transmit the data to the wireless device.

Hybrid automatic repeat request (ARQ) with spatial diversity

A wireless system comprises a controlling node and multiple antenna processing nodes coupled to the controlling node but separated from each other. The controlling node receives () first soft bit information from a first antenna processing node, the first soft bit information corresponding to reception of a wireless transmission. Responsive to determining that it cannot decode transmitted bits using the first soft bit information, the controlling node requests () and receives () second soft bit information from a second antenna processing node, the second soft bit information also corresponding to the first wireless transmission from the wireless device and having been buffered by the second antenna processing node. The controlling node decodes () bits from the first wireless transmission using both the first and second soft bit information. The controlling node may then signal the antenna processing nodes that they can discard buffered information for the wireless transmission.

Chase combining in a distributed wireless system

Systems and methods for providing efficient antenna calibration that are particularly beneficial for a radio system having a large antenna array are disclosed.

Efficient antenna calibration for large antenna arrays

A base station for detecting a Physical Random Access Channel (PRACH) transmission from a User Equipment device (UE) comprises a radio device and at least one additional device. The radio device comprises narrowband receivers respectively coupled to antenna elements of an antenna array. Each narrowband receiver is configured to receive a signal from a respective antenna element and process the signal to provide received symbols for a PRACH received via the respective antenna element. The radio device also comprises accumulation circuitry configured to, for each antenna element, accumulate a subset of the received symbols for the PRACH received via the antenna element to output a first averaged symbol for the PRACH received via the antenna element. The at least one additional device is configured to receive, from the radio device, the first averaged symbols and process the first averaged symbols to perform PRACH detection for one or more receive beams.

Cost efficient PRACH detection

A receiver () featuring a distributed antenna combining system performs two stages of antenna combining. An antenna array () receives () L streams, or information flows, from UEs (), and outputs antenna signals on N antenna ports. N parallel radio receivers () frequency convert () the N received signals to baseband. A first antenna combining circuit () applies () a relatively low-complexity form of antenna combining (e.g., MRC) to the N radio signals to generate K streams of virtual information. A second antenna combining circuit () applies () a relative high-complexity form of antenna combining (e.g., IRC) to the K virtual streams to generate L information streams. In one embodiment, antenna elements may have different polarization directions, and the first antenna combining circuit () generates two, differently-polarized virtual information streams for each UE () stream.

Distributed antenna combining

Crest factor reduction techniques and apparatus provide good performance while reducing the impact to power consumption and implementation cost. An example method begins with identifying multiple non-overlapping and separated signal segments in a signal made up of a sequence of digital signal values, each identified segment being an interval in which at least one the digital signal values exceeds a predetermined threshold. For each identified signal segment, an overshoot vector representing the extent by which the identified signal segment exceeds the predetermined threshold is calculated. Each overshoot vector is separately filtered with a digital filter having one or more passbands corresponding to in-band portions of the signal. Each filtered overshoot vector is separately scaled, in some embodiments, and each scaled, filtered, overshoot vector is subtracted from the corresponding portion of the signal, to obtain a compensated signal having a reduced crest factor.

Crest factor reduction in a radio transmitter

An envelope tracking RF transmitter calibration procedure calculates both a supply voltage to apply to a power amplifier for a modulated signal envelope to achieve ISO-gain, and a timing delay adjustment to time-align the applied supply voltage and the modulated signal to minimize distortion due to time delay error. An ISO-gain surface is calculated, as a function of the envelope of a modulated signal and the power amplifier supply voltage, for each of a plurality of desired gain values. As the envelope is swept through a predetermined range of values, demodulated outputs at predetermined points are sampled, and a set of non-linear functions relating the supply voltage to the envelope, which achieve the desired gain at the sampled points, are derived, using surface interpolation between the predetermined gain surface points. Data defining the functions are stored for use during transmitter operation. Distortion components in the transmitter output are detected, and are separated into even components representing time delay error distortion, and odd components representing transmitter saturation distortion. A timing delay value is calculated that minimizes the time delay error distortion.

Envelope tracking RF transmitter calibration

Growing community of inventors

Lund, Sweden

Torsten John Carlsson