Motorola Corporation

Motorola Mobility LLC

Nokia Solutions and Networks Oy

Xiaoyong Yu

Alan P Rottinghaus

Jian Jun Wu

Shirish Nagaraj

Xiangyang Chen

Ke-Kang Chin

Timothy J Wilson

Nicholas William Whinnett

Michael N Kloos

Steven Andrew Wood

Thomas J Kovarik

Mang Zhu

Ming D Tan

Gregory Peter Spock

Described are techniques for limiting bandwidth requirements for user equipment UE data sent on a front haul link between a remote radio head RRH and a baseband unit BBU. For a given UE a subset of a plurality of beams is selected based on received energies of the plurality of beams, and for the given UE only data from the selected subset of beams transmitting on a front haul link. Multiple techniques are detailed for how the subset is selected, including (when UE allocation information is available) averaged received beam energy, total received beam energy, maximum received beam energy and also (when UE allocation information is not available). For further bandwidth reduction a special data compression technique uses the received energies of each beam to select a minimum gain offset value after dividing the data into I and Q components.

Bandwidth reduction with beamforming and data compression

A method includes, for a selected user equipment for signals corresponding in part to the selected user equipment and received by antennas from a number of cells, wherein each cell has one or more antennas, and wherein each signal is from an individual one of the antennas, performing the following: estimating carrier frequency offset for each cell using one or more of the signals from the cell; performing frequency offset correction on each signal from each cell by using at least the estimated carrier frequency offset for an associated cell; estimating a channel for each frequency offset corrected signal; and combining, using the estimated channels, each of the frequency offset corrected signals to generate one or more estimates of one or more symbols transmitted from the selected user equipment. A second frequency offset correction may be performed subsequent to the combining. Apparatus, computer programs, and software are also disclosed.

Frequency error correction for LTE uplink CoMP

The specification and drawings present a new method, apparatus and software related product (e.g., a computer readable memory) for a timing offset/error estimate (TOE) method, e.g., for a LTE UL receiver. This may especially beneficial for the MU-MIMO and/or CoMP with MAAS applications, where the conventional methods do not work properly due to a strong interference among users (UEs) sharing the same radio resource. Two approaches (separately or in combination) may be used to improve TOE quality. First, the timing offset/error may be calculated using phase difference for pilot pairs with non-adjacent pilots/carriers having a larger separation between subcarriers than for pilot pairs with adjacent subcarriers. Second, a modified pilot sequence for timing offset estimate may be created using sliding an averaging window. This can effectively remove interference which is critical for the MU-MIMO and CoMP applications.

Timing error estimate of UL synchronization

Various embodiments to provide cancellation techniques that can be used to address the self-quieter problem are described. For example, a receiver that includes a tone selector and a self-quieter suppressor is provided. The tone selector () determines and selects a self-quieter corrupted tone from a frequency domain signal that exhibits a self-quieter. The self-quieter suppressor () determines an initial phase, an angular speed and an amplitude estimate for the frequency domain self-quieter. The suppressor then generates a reconstructed frequency domain self-quieter using the initial phase, the angular speed and the amplitude estimate and subtracts the reconstructed frequency domain self-quieter from the corrupted tone to produce a self-quieter suppressed tone to replace the corrupted tone. Such an approach can realize a significant reduction in processing and complexity, as compared to known alternatives, making it an attractive and cost-effective solution for dealing with the self-quieter problem.

Adaptive self-quieter suppression for OFDM wireless communication systems

An apparatus and method for synchronization in an uplink spatial division multiple access (UL SDMA) mode of a WiMAX wireless communication system includes a first step () of allocating a mixed sequence of first and second tile patterns for mobile station uplink slots. A next step () includes detecting embedded pilot signals in mobile station data traffic. A next step () includes calculating first and second pilot signal phase difference within the respective first and second tile patterns. A next step () includes estimating a time error and a frequency error of the pilot signals. A next step () includes sending information about the time and/or frequency error to the mobile station for use in synchronization ().

Synchronization in an uplink spatial division multiple access mode of a WiMAX wireless communication system

A method, a system and a receiver device provide timing and frequency correction in a spatial division multiple access (SDMA) system. A timing and frequency correction (TFC) logic/utility obtains a timing error estimate by using pilot symbols on a slot of six tiles. The TFC logic estimates the timing error based on pilot phase differences between unique pairs of tiles when the frequency separation of the tiles is less than a threshold value. When none of the unique pairs of tiles satisfies the threshold value, the TFC logic estimates timing error based on an exhaustive search for each candidate phase error value. The TFC logic performs timing error correction via a timing error estimate based on pilots from the symbols received on each antenna. The TFC logic performs inexplicit frequency error correction according to phase differences based on relative symbol indices.

Up-link SDMA receiver for WiMAX

Disclosed is a method and communication device for suppressing interference. The method comprises performing, with a turbo decoder (), at least one turbo decoding attempt () on a received signal (). The turbo decoding attempt generates at least one whole word code bit therefrom (). The whole word code bit () corresponds to a group of bits comprising a transmitted symbol. The method determines if the whole word code bit () has a confidence level exceeding a given threshold (). If the whole word code bit () does have a confidence level exceeding the given threshold, the whole code word bit is selected for use in data symbol recovery ().

Turbo interference suppression in communication systems

A method () and a system () for processing an orthogonal frequency division multiplexing (OFDM) signal. At least one portion of an OFDM symbol () that exceeds an amplitude limiting threshold can be identified. The identified portion of the OFDM symbol () can be filtered to generate a pre-distortion noise (). The OFDM symbol () and the pre-distortion noise () can be combined to generate a pre-distorted OFDM symbol ().

Digital pre-distortion for orthogonal frequency division multiplexing (OFDM) signals

A radio device operable to compensate for a large RF filter group delay variation is provided. The radio device includes a receiving unit operable to receive an OFDM signal that comprises pilot subcarrier signals and data subcarrier signals. The radio device further includes a group delay (GD) compensator, operable in frequency domain, and configured to perform phase rotation to correct a group delay individually on tones of an OFDM symbol. The phase rotation is calculated as a function of the phase shifts of the received pilot subcarrier signals and subcarrier index.

Method and system for radio frequency (RF) group delay compensation in a broadcast system

Method and system for synchronizing a receiver in an Orthogonal Frequency Division Multiplexing (OFDM) system. The method comprises transforming () a received signal from the time domain into the frequency domain to produce a transformed signal. The method further comprises rotating () each set of ranging tones of the transformed signal in the frequency domain based on a corresponding tone index to produce a set of phase-rotated frequency domain received ranging tones that is equivalent to time domain shifted ranging signals. Each ranging tone is rotated iteratively over a predefined set of delay-values and each delay-value within the predefined set of delay-values ranges from zero to a predetermined time delay. Also, the method comprises computing () a detection metric corresponding to each delay-value within the predefined set of delay-values based on the set of phase-rotated frequency domain received ranging tones.

Method and system for synchoronizing a receiver in an OFDM system

A base station receives () OFDMA messages from a plurality of end user platforms that share all used tones within at least one OFDMA symbol. By one approach this base station then uses () a fixed starting time to select contiguous samples from received aggregate multi-user signals wherein the fixed starting time is offset from a reference time that comprises a time at which the base station expects to be receiving the signals from all end users. In combination with the time offset approach noted above or in lieu thereof the base station can process () selected contiguous samples using fast Fourier transform and then provide () phase rotation with respect to those processed samples. When applying phase rotation, by one approach a phase rotation can be applied () to the aggregate multi-user signal and, in addition, individual phase rotation can be applied () as determined on a user-by-user basis.

Orthogonal frequency division multiple access message processing method and apparatus

Estimates of carrier signal power S and interference-noise NI at the output of the equalizer in a wireless communication system is obtained by (i) determining the variance, &#x3c3;, of the noise at the output of the equalizer dependent upon the equalization matrix, Wand an estimate of the variance &#x3c3;of the noise at the receiving antennas, (ii) determining the interference, &#x3c3;, at the output of the equalizer dependent upon the equalization matrix, W, a transfer function matrix, H, of transmission paths between transmitting antennas and receiving antennas, and an estimate &#x3c3;of the variance of the transmitted signals and (iii) determining the power, S, of the carrier signal at the output of the equalizer dependent upon W, H and &#x3c3;. The estimate of the interference-noise NI is calculated as NI=&#x3c3;+&#x3c3;. These values may be used to facilitate adaptation of the wireless communication system.

Method and apparatus for carrier power and interference-noise estimation in space division multiple access and multiple-input/multiple-output wireless communication systems

A method, system, and communication network for grouping a pair of independent information signals on the same time-frequency orthogonal frequency division multiplexing (OFDM) resources for uplink (UL) collaborative SDMA, in a wireless communication system. An uplink scheduling (ULS) utility employs an estimated channel gain associated with the transmission path(s) of each user to create a pairing metric that effectively computes the correlation between each pair of independent information signals on a specific sub-carrier frequency channel. Pairs of information signals are considered as possible groupings when the values of the corresponding pairing metrics are less than a threshold maximum value. An optimal selection of final pairings is based on the relative values of the pairing metric(s) and other priority conditions which may include quality of service requirements. The ULS utility enables the UL scheduler to pair information signals with a clear spatial distinction and minimal correlation.

Method for uplink collaborative SDMA user pairing in WIMAX

A communication device is provided that is capable of operating in an OFDM or communication system and that provides for cancellation of in-band spurs. The communication device identifies a bin of multiple bins associated with an output of an inverse transformer and comprising a spur and estimates one or more spur phase parameters and a spur amplitude in association with the identified bin. In one embodiment of the present invention, the one or more spur phase parameters includes a spur initial phase and a spur change rate. When the communication device receives a signal from another communication device, the communication device transforms the received signal to produce a multiple parallel output signals that are each associated with a bin of the multiple bins and cancels a spur in an output signal associated with the identified bin based on the estimated one or more spur phase parameters and spur amplitude.

Method and apparatus for spur cancellation in an orthogonal frequency division multiplexing communication system

A wireless transceiver () that produces soft decisions for received, block error correction encoded codewords and a confidence indicator signifying a likelihood of errors in the detected data. The wireless transceiver () processes block encrypted signals, such as feedback channel messages in a WiMax uplink. Upon receiving a signal, a soft decision is determined for received block encoded codewords. A difference is calculated between a soft decision metric for a most likely detected codeword and a soft decision metric for a next most likely detected codeword. This difference is normalized based upon the total decoder input power received over the received signal (). The normalized difference is then scaled by a channel dependent factor and is time filtered. The normalized and time filtered confidence indicator output () is able to be provided to a wireless network controller to assess the usability of the received data.

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Grayslake, IL, United States of America

Xiaoyong Yu