A method for estimating a channel state of an audio/video signal includes: estimating a first response and a second response according to the audio/video signal, wherein the first response corresponds to an echo path and the second response corresponds to a reference path; calculating a plurality of phase differences at a plurality of time points between the first response and the second response; determining whether the echo path is a Doppler path according to the phase differences; and when it is determined that the echo path is the Doppler path, calculating a phase rotation frequency of the Doppler path according to a difference between at least two of the phase differences.

A communication device includes a Session Management Module (SMM) that controls data that is communicated via a first communication link and the data that is communicated via a second communication link and causes the following steps to be performed: discovering a second device via a first communication link, establishing a communication session between the communication device and the second device over a first subset of the communication links (the selection of the first subset of the communication links is a function of a communication link selection rule), exchanging a first type of data over the at least one of the first subset of communication links (the at least one of the first subset of communication links is selected in accordance with a communication link data selection rule), and ending the communication session between the communication device and the second device.

Embodiments are provided for guard band utilization for synchronous and asynchronous communications in wireless networks. A user equipment (UE) or a network component transmits symbols on data bands assigned for primary communications. The data bands are separated by a guard band having smaller bandwidth than the data bands. The UE or network component further modulates symbols for secondary communications with a spectrally contained wave form, which has a smaller bandwidth than the guard band. The spectrally contained wave form is achieved with orthogonal frequency-division multiplexing (OFDM) modulation or with joint OFDM and Offset Quadrature Amplitude Modulation (OQAM) modulation. The modulated symbols for the secondary communications are transmitted within the guard band.

An interference suppression (IS) time/frequency zone for improved interference suppression at the user equipment (UE) is provided. The IS time/frequency zone can be scheduled and set up using existing signaling of the Almost Blank Subframe (ABS) framework. This includes using the existing signaling of the ABS framework to schedule the IS time/frequency zone, coordinate transmission parameters among base stations for the IS time/frequency zone, and signal the IS time/frequency zone to the UE. In another aspect, interfering base stations align respective reference signals during the IS time/frequency zone, which allows the UE to measure the channels from its serving base station and/or the interfering base stations(s). With channel state information knowledge at the UE, interference alignment can be achieved at the UE during the IS time/frequency zone.

A WAP including: a sounding mode module, a sounding matrix generator, a sounding aggregator, a gain normalizer and a beamforming expansion module. The sounding mode module determines whether a number of communication streams supported by the WAP matches the number of streams contained in a sounding response from a station, and initiates a composite set of soundings when those capabilities do not match. The sounding matrix generator generates linearly independent spatial mapping matrices each associated with a corresponding one of the set of composite soundings and at least one reference SMM. The sounding aggregator aggregates partial sounding feedback matrices received from the targeted station node in response to the composite soundings. The gain normalizer normalizes the partial sounding feedback matrices utilizing the reference SMM. The beamforming expansion module expands the aggregated sounding feedback matrices into a full beamforming matrix for spatially mapping downlink communications.

Systems and methods described herein provide a method for detecting beamformed detecting beam-formed orthogonal frequency division multiplexing (OFDM) packets. The method includes receiving, at a receiver, a data signal including a data packet, and selecting a set of frequency domain tones associated with the data signal for channel estimation. The method further includes calculating a plurality of differential parameters between adjacent frequency domain tones from the set of frequency domain tones. The method further includes identifying a jump when a first differential parameter from the plurality of differential parameters exceeds a jump threshold. The method further includes obtaining an accumulative count of jumps for the set of frequency domain tones, and identifying the data packet is beamformed when the accumulative count exceeds a jump limit.

A transmission method for transmitting a first modulated signal and a second modulated signal in the same frequency at the same time. Each signal has been modulated according to a different modulation scheme. The transmission method applies precoding on both signals using a fixed precoding matrix, applies different power change to each signal, and regularly changes the phase of at least one of the signals, thereby improving received data signal quality for a reception device.

In a method for beamforming in a multiple input multiple output (MIMO) communication system, a data unit is received from a communication device via a MIMO communication channel, and it is determined whether the data unit satisfies one or more selection criteria. Further, when it is determined that the data unit satisfies the one or more selection criteria, the data unit is selected to be used in developing a steering matrix for transmitting data units to the communication device.

An end-to-end multimedia streaming system can include a streaming server and a destination. The streaming server includes a content source, which sends multiple description coding-encoded content over a plurality of paths to the destination. The destination includes an aggregator for aggregating the descriptions from the multiple paths, decoding and recombining them to recover the content. A feedback sender at the destination generates traffic performance variables based on the channel conditions of the multiple paths, and sends these variables to a feedback receiver at the streaming server. The feedback receiver utilizes the feedback information to make adjustments to the transmissions of the content, and to synchronize the transmissions over the multiple paths.

A mobile communication system performs downlink multi-antenna transmission by applying a precoder matrix that defines transmission directionality of downlink and a rank that defines number of signal sequences of the downlink. The mobile communication system comprises a user terminal that feeds back feedback information of a target frequency band, to a base station. The feedback information includes combinations of precoder matrix information indicating the precoder matrix and rank information indicating the rank.