Qualcomm Incorporated

Agere Systems Inc.

Richard Van Nee

Hemanth Sampath

Albert Van Zelst

Geert Arnout Awater

Gregory C Steele

Santosh Paul Abraham

Sameer Vermani

James M Gardner

Simone Merlin

Maarten Menzo Wentink

Lin Yang

Stephen Jay Shellhammer

Alok Aggarwal

Albert Van Zeist

Geert Arnoult Awater

Embodiments of the present disclosure generally relate to communication, and more specifically to distributed multiple-input multiple-output (MIMO) systems. For certain aspects, methods and apparatus are provided for transmitting a start frame containing information regarding parallel MIMO transmissions in a transmit opportunity and transmitting one or more parallel MIMO streams in accordance with the information contained in the start frame. For certain aspects, methods and apparatus are provided for receiving a start frame containing information regarding parallel MIMO transmissions in a transmit opportunity and transmitting one or more parallel MIMO streams in accordance with the information contained in the start frame. For certain aspects, methods and apparatus are provided for receiving a start frame containing information regarding parallel MIMO transmissions in a transmit opportunity and receiving one or more parallel MIMO streams in accordance with the information contained in the start frame.

Start frame for distributed MIMO

Techniques and apparatus for controlling the transmit power of an uplink (UL) signal from a user terminal in a wireless communications system in an effort to achieve some target characteristic, such as a target carrier-to-interference (C/I) ratio, at an access point (AP) are provided. In this manner, such a user terminal may help avoid or compensate for imbalances in received radio frequency (RF) power between UL signals received from multiple user terminals by the AP. For example, the transmit power at each user terminal may be controlled in an effort to achieve a target post-processing C/I ratio of 28 dB per spatial stream in an effort to reduce large power imbalances and optimize throughput per user terminal. The user terminal and the AP may compose part of a multiple-input multiple-output (MIMO) communication system utilizing spatial-division multiple access (SDMA) techniques.

Power control for wireless LAN stations

Certain aspects of the present disclosure provide techniques for detecting presence of a Bluetooth device in the vicinity of a WiFi device by sensing the spectrum of the Bluetooth device using a sequence of energy detection measurements, generating a test statistic based on the measurements and comparing the test statistic to a threshold.

Spectrum sensing of bluetooth using a sequence of energy detection measurements

An apparatus for wireless communications is provided including a processing system. The processing system is configured to determine path-losses between the apparatus and a plurality of wireless nodes, to group the plurality of wireless nodes into sets based on the determined path-losses, and to exchange data with at least one of the wireless nodes in one of the sets.

Multiuser scheduling in WLAN systems

Systems and/or methods for communications wherein a plurality of spatial streams are received. Each of these spatial streams comprises a symbol having at least one phase shifted pilot signal. The Minimum Mean Square Error (MMSE) estimates of the phase shifted pilot signals are computed and the MMSE estimates are used to estimate phase errors for the symbols.

Uplink SDMA pilot estimation

A base station for compensating for frequency offsets is described. The base station includes a processor and instructions stored in memory. The base station computes a time domain impulse response estimate and applies frequency offset compensation to the time domain impulse response estimate to obtain a time domain offset-compensated impulse response estimate. A frequency domain offset-compensated impulse response estimate is computed. The frequency domain offset-compensated impulse response estimate is used to compute beamforming weights. The base station transmits data using the beamforming weights.

Compensating for frequency offsets on a base station

Certain aspects of the present disclosure relate to techniques for constructing a long training field (LTF) sequence in a preamble to reduce a peak-to-average power ratio (PAPR) at a transmitter.

Constructing very high throughput long training field sequences

Certain aspects of the present disclosure present a technique for designing a signal (SIG) field of a mixed mode preamble transmitted to a plurality of user terminals. The SIG field can signal a number of spatial streams assigned to each user. The SIG field is designed such that a robust interference cancellation can be achieved at each user terminal.

Mixed mode preamble design for signaling number of streams per client

The present disclosure proposes a method for precoding of transmission signal at an access point of a multiuse system based on eigenmode selection and minimum mean square error (MMSE) processing. The most reliable eigenmodes of every multiple-input multiple-output (MIMO) channel in the system can be selected at each user terminal and corresponding eigenvalues and eigenvectors can be fed back to the access point. The linear MMSE precoding (beamforming) applied at the access point based on the selected eigenmodes may provide an improved transmission capacity performance.

Precoding technique for multiuser MIMO based on eigenmode selection and MMSE

Methods and apparatus for orthogonal pilot tone mapping in Multiple-In and Multiple-Out (MIMO) and Spatial Division Multiple Access (SDMA) systems are disclosed. An aspect of the method includes identifying a plurality of symbol periods within which symbols representing encoded data are to be transmitted in a plurality of spatial streams over a communication channel; identifying a plurality of pilot tone values for a plurality of pilot tones in the plurality of symbol periods to create a pilot tone mapping, wherein the identified pilot tone values are such that a receiver, when receiving at least some of the plurality of pilot tones, is provided with signals enabling the receiver to characterize and mitigate any communication impairments, and potentially obtain transmit spatial stream diversity benefits, wherein at least two of the pilot tone values in the pilot tone mapping are orthogonal when the symbols are combined over at least one dimension; and transmitting the symbols and the plurality of pilot tones over the plurality of spatial streams for the plurality of symbol periods.

Method and apparatus for orthogonal pilot tone mapping in multiple-in and multiple-out (MIMO) and spatial division multiple access (SDMA) systems

Methods and systems for communications that generate a plurality of spatial streams, wherein each of the spatial streams comprises a data packet with a training sequence; and multiply at least a portion of the training sequence in each of the spatial streams with a different spreading sequence. Methods and systems that receive a plurality of spatial streams, wherein each of the spatial streams comprises a data packet with a training sequence; multiply at least a portion of the training sequence in each of the spatial streams with a different spreading sequence; and decode the plurality of spatial streams based on the different spreading sequences.

Training sequences for very high throughput wireless communication

A packet detector joint detects 802.11a packets, 802.11b packets and interference that is within a monitored frequency range but is not formatted as 802.11a packets or 802.11b packets. The packet detector can use signals from one or more antennas. Detection of signals is done using differentially detected correlations. In addition to packet detection, the packet detector can identify signal levels, noise levels and locations of narrowband interference. The process of packet detection and identifying other indicators can be done simultaneously and as the signal is being received.

Joint packet detection in a wireless communication system with one or more receivers

Joint packet detection in wireless communication system with one or more receiver

An OFDM system uses a normal mode which has a symbol length T, a guard time TG and a set of N sub-carriers, which are orthogonal over the time T, and one or more fallback modes which have symbol lengths KT and guard times KTG where K is an integer greater than unity. The same set of N sub-carriers is used for the fallback modes as for the normal mode. Since the same set of sub-carriers is used, the overall bandwidth is substantially constant, so alias filtering does not need to be adaptive. The Fourier transform operations are the same as for the normal mode. Thus fallback modes are provided with little hardware cost. In the fallback modes the increased guard time provides better delay spread tolerance and the increased symbol length provides improved signal to noise performance, and thus increased range, at the cost of reduced data rate.

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De Meern, Netherlands

Richard Van Nee