A method for channel estimation, performed by a wireless transmit/receive unit (WTRU), includes: receiving a plurality of input signals, generating a plurality of sensing matrices for the input signals, generating an augmented sensing matrix and an augmented observation vector according to the sensing matrices and the input signals, estimating a plurality of channel delay parameters according to the augmented sensing matrix and the augmented observation vector, and estimating channel information according to the channel delay parameters.

Embodiments of the present disclosure describe systems, devices, and methods that may provide channel estimation and compensation in high speed scenarios, which may include user equipment carried on a high speed train. Embodiments may employ cell-specific reference signal (CRS)-based time-domain channel estimation and compensation.

A method for estimating noise in a channel impulse response measurement. In some embodiments, the method includes calculating a first average energy, the first average energy being an average energy of a sequence of time-domain samples of the channel impulse response measurement; setting a detection threshold; identifying a first subset of the sequence of time-domain samples, each element of the first subset of the sequence of time-domain samples having an energy less than the detection threshold; and calculating a second average energy, the second average energy being an average energy of the first subset of the sequence of time-domain samples.

The predicted explosive growth in the number of wireless devices and mobile applications utilizing wireless networks makes it time for engineers to face the high network densification challenge where massive numbers of terminal devices (TDs) coexist and require both high-rate and low-latency wireless data transmissions. We describe a multiple access point (AP) Time-Reversal Division Multiple Access (TRDMA) downlink system that utilizes the natural spatial and temporal focusing properties of Time Reversal (TR) based communications, where the interference to unintended receivers is automatically at least partially mitigated. As a result, in some implementations, the TRDMA system can achieve full or nearly-full spectrum reuse without any coordination among APs. The performance of the TRDMA system is investigated in both an open access model where an AP is open to all the TDs and a closed access model where an AP is only open to specific TDs. It is shown that in the open access model, the TRDMA system can be easily extended by adding more APs to fit various scenarios. In the closed access model, the TRDMA system is failure-robust such that the performance degradation caused by neighboring APs is graceful. Moreover, the packet delay of the TRDMA system can be much lower than that of the IEEE 802.11 based system.

The present application describes a computer-implemented method for frequency hopping including configuring a radio front end to operate on a first frequency; receiving a transmit signal in a first path in the radio front end; amplifying a transmit signal in the first path; phase shifting the transmit signal in a second path in the radio front end, the second path being different from the first path; coupling the amplified transmit signal to a third path in the radio front end; coupling the phase-shifted transmit signal in the second path to the amplified transmit signal in the third path to form a carrier-cancelled signal in a fourth path in the radio front end in the radio front end; phase shifting the carrier-cancelled signal in the fourth path; coupling the phase-shifted carrier-cancelled signal in the fourth path to the amplified transmit signal in the first path; and reconfiguring the radio front end to operate on a second frequency.

This invention relates to methods and systems for determining whether a reference point in a location system has changed using the entropy of channel impulse responses. In one embodiment a method of determining whether the location of a first one of a plurality of reference points used in a location system has changed is provided. The reference points each have a known initial position and the method includes the steps of: estimating a channel impulse response of a wireless channel between the first reference point and a second of said plurality of reference points; determining the difference between the estimated channel impulse response and a previously-estimated channel impulse response of the wireless channel; estimating an entropy of the difference between the channel impulse responses; and determining, from said comparison, whether the location of the first reference point has changed. In another embodiment the method includes the steps of: estimating an entropy of the channel impulse response of a wireless channel between the first reference point and a second of said plurality of reference points; comparing the estimated entropy to a previously-estimated entropy for the channel impulse response of the wireless channel; determining, from said comparison, whether the location of the first reference point has changed.

It must be understood that such structure comprising CP1 and CS1 is implicitly there, even if the transmitter only explicitly prepends a CP1. Indeed, and explained by example of a full duplex multicarrier system, the receiver will still be required to discard a number of samples equivalent to a cyclic suffix from the received time samples of each symbol to obtain orthogonality with the echo received from the transmit symbols.

There are disclosed techniques (e.g., apparatus, methods) for estimating an impulse response of a linear system. An apparatus is configured to generate a transmit signal on the basis of a first sequence. The apparatus is configured to obtain a receive signal and to multiply the receive signal with a second sequence, to obtain a modified receive signal, wherein the second sequence is different from the first sequence. The apparatus is configured to analog-to-digital, ADC, convert an integration result in order to obtain a sample value, the integration result being based on an integration of the modified receive signal over a period of time. The apparatus is configured to obtain an estimate of the impulse response on the basis of a plurality of sample values.

A reception device is disclosed. The reception device comprises: a reception unit for receiving a signal including at least one of a channel estimation signal, a transmitter identification (TxID) signal, and a preamble signal; a TxID detection unit for detecting the TxID signal from the received signal; a TxID processing unit for changing the frequency band of the detected TxID signal, on the basis of a result of the detection of the TxID signal; and an attenuation unit for attenuating the TxID signal in the received signal by using the TxID signal having the changed frequency band.

A radio frequency system. In some embodiments, the system includes a one-bit receiver, and the one-bit receiver includes a digital pseudo random noise generator, a one-bit digital to analog converter, a power combiner, a one-bit analog to digital converter, and a digital subtraction circuit. The digital pseudo random noise generator produces a signal added to the received signal before analog to digital conversion. After analog to digital conversion, a delayed version of the dither is subtracted from the digital signal.