Abstract: The present teaching relates to wireless Internet of Things. In one example, a time reversal client is disclosed. The time reversal client comprises a processor, a memory communicatively coupled with the processor, and a set of instructions, when executed by the processor based on the memory, that cause the time reversal client to perform the following steps: communicatively coupling with a time reversal server through a network, obtaining a set of channel state information (CSI), wherein the set of CSI is captured when at least one probing signal is sent from the wireless transmitter to the wireless receiver through a wireless multipath channel associated with a space, and causing the set of CSI to be sent to the time reversal server through the network.

Abstract: 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.

Abstract: A time-reversal wireless system comprising a first wireless transceiver of a time-reversal client, one or more second wireless transceiver and/or a time-reversal client with the first wireless transceiver. The first wireless transceiver of the time-reversal client is wirelessly coupled to the one or more second wireless transceiver through a wireless broadband multipath channel associated with a space. The time-reversal client contains the first wireless transceiver. The time-reversal client also contains a processor and a memory configured to obtain a set of channel state information (CSI) in a channel probing phase, and/or to obtain a set of location-specific signatures based on the set of CSI and/or a time reversal operation in a channel probing phase.

Abstract: An apparatus for detecting events includes a processor and a storage device storing instructions that when executed by the processor cause the processor to train a classifier for classifying channel state information (CSI) and detecting an event based on the classification of the CSI obtained during a monitoring phase. The training of the classifier includes: for each of the known events to be detected, during a time period in which the known event occurs in a venue, obtain training CSI of a wireless multipath channel between a wireless transmitter and a wireless receiver in the venue, in which the training CSI is derived from one or more probing signals sent from the transmitter through the wireless multipath channel to the receiver, and train the classifier based on the known events and the training CSI associated with each of the events.

Abstract: An apparatus for determining symbol timing in a communication system is provided. The apparatus includes a memory communicatively coupled to at least one processor. The at least one processor is configured to receive a first signal that includes a preamble sent at a first sampling rate with a first modulation through a channel and a data frame sent at a second sampling rate with a second modulation through the channel. The preamble includes a received code sequence, and the data frame includes a plurality of data symbols. The at least one processor is configured to compute a second signal that represents an estimate of an equivalent channel response using at least one of a known code sequence and the received first signal, down-sample the second signal and compute signal-to-interference-plus-noise ratios at a plurality of candidate timing offsets, and determine a symbol timing based on a particular timing offset associated with one of the computed signal-to-interference-plus-noise ratios.

Abstract: The present teaching relates to wireless Internet of Things. In one example, a time reversal client is disclosed. The time reversal client comprises a processor, a memory communicatively coupled with the processor, and a set of instructions, when executed by the processor based on the memory, that cause the time reversal client to perform the following steps: communicatively coupling with a time reversal server through a network, obtaining a set of channel state information (CSI), wherein the set of CSI is captured when at least one probing signal is sent from the wireless transmitter to the wireless receiver through a wireless multipath channel associated with a space, and causing the set of CSI to be sent to the time reversal server through the network.

Abstract: An apparatus for detecting events includes a processor and a storage device storing instructions that when executed by the processor cause the processor to train a classifier for classifying channel state information (CSI) and detecting an event based on the classification of the CSI obtained during a monitoring phase. The training of the classifier includes: for each of the known events to be detected, during a time period in which the known event occurs in a venue, obtain training CSI of a wireless multipath channel between a wireless transmitter and a wireless receiver in the venue, in which the training CSI is derived from one or more probing signals sent from the transmitter through the wireless multipath channel to the receiver, and train the classifier based on the known events and the training CSI associated with each of the events.

Abstract: A base station of a time reversal communication system is provided. The base station receives a set of channel probing signals from a set of terminal devices, determines channel impulse responses based on the channel probing signals, and determines location-specific signature waveforms based on the channel impulse responses, in which each of the location-specific signature waveforms is associated with a particular location of the respective terminal device. The base station generates a set of medium access layer parameters, in which each medium access layer parameter is associated with a particular one of the terminal devices. For each terminal device, the base station generates transmit data signals based on data intended for the terminal device, and the medium access layer parameter and the location-specific signature waveform associated with the terminal device. The base station transmits the transmit data signals wirelessly to the terminal devices.

Abstract: A handshaking process for time-reversal wireless communication is provided. A first device receives a handshake signal transmitted from a second device through multiple propagation paths, the handshake signal including a preamble and a training sequence, in which the training sequence includes a sequence of symbols known to the first and second devices. A synchronization index is determined based on the preamble, and the training sequence in the handshake signal is identified based on the synchronization index. A channel response signal is determined based on the received training sequence, and a signature waveform that is a time-reversed signal of the channel response signal is generated. A transmission signal is generated based on transmit data and the signature waveform, in which the transmit data are data configured to be transmitted to the second device.

Abstract: A handshaking process for time-reversal wireless communication is provided. A first device receives a handshake signal transmitted from a second device through multiple propagation paths, the handshake signal including a preamble and a training sequence, in which the training sequence includes a sequence of symbols known to the first and second devices. A synchronization index is determined based on the preamble, and the training sequence in the handshake signal is identified based on the synchronization index. A channel response signal is determined based on the received training sequence, and a signature waveform that is a time-reversed signal of the channel response signal is generated. A transmission signal is generated based on transmit data and the signature waveform, in which the transmit data are data configured to be transmitted to the second device.

Abstract: A time-reversal wireless system comprising a first wireless transceiver of a time-reversal client, one or more second wireless transceiver and/or a time-reversal client with the first wireless transceiver. The first wireless transceiver of the time-reversal client is wirelessly coupled to the one or more second wireless transceiver through a wireless broadband multipath channel associated with a space. The time-reversal client contains the first wireless transceiver. The time-reversal client also contains a processor and a memory configured to obtain a set of channel state information (CSI) in a channel probing phase, and/or to obtain a set of location-specific signatures based on the set of CSI and/or a time reversal operation in a channel probing phase.

Abstract: A handshaking process for time-reversal wireless communication is provided. A first device receives a handshake signal transmitted from a second device through multiple propagation paths, the handshake signal including a preamble and a training sequence, in which the training sequence includes a sequence of symbols known to the first and second devices. A synchronization index is determined based on the preamble, and the training sequence in the handshake signal is identified based on the synchronization index. A channel response signal is determined based on the received training sequence, and a signature waveform that is a time-reversed signal of the channel response signal is generated. A transmission signal is generated based on transmit data and the signature waveform, in which the transmit data are data configured to be transmitted to the second device.

Abstract: A handshaking process for time-reversal wireless communication is provided. A first device receives a handshake signal transmitted from a second device through multiple propagation paths, the handshake signal including a preamble and a training sequence, in which the training sequence includes a sequence of symbols known to the first and second devices. A synchronization index is determined based on the preamble, and the training sequence in the handshake signal is identified based on the synchronization index. A channel response signal is determined based on the received training sequence, and a signature waveform that is a time-reversed signal of the channel response signal is generated. A transmission signal is generated based on transmit data and the signature waveform, in which the transmit data are data configured to be transmitted to the second device.

Abstract: A handshaking process for time-reversal wireless communication is provided. A first device receives a handshake signal transmitted from a second device through multiple propagation paths, the handshake signal including a preamble and a training sequence, in which the training sequence includes a sequence of symbols known to the first and second devices. A synchronization index is determined based on the preamble, and the training sequence in the handshake signal is identified based on the synchronization index. A channel response signal is determined based on the received training sequence, and a signature waveform that is a time-reversed signal of the channel response signal is generated. A transmission signal is generated based on transmit data and the signature waveform, in which the transmit data are data configured to be transmitted to the second device.

Abstract: A handshaking process for time-reversal wireless communication is provided. A first device receives a handshake signal transmitted from a second device through multiple propagation paths, the handshake signal including a preamble and a training sequence, in which the training sequence includes a sequence of symbols known to the first and second devices. A synchronization index is determined based on the preamble, and the training sequence in the handshake signal is identified based on the synchronization index. A channel response signal is determined based on the received training sequence, and a signature waveform that is a time-reversed signal of the channel response signal is generated. A transmission signal is generated based on transmit data and the signature waveform, in which the transmit data are data configured to be transmitted to the second device.

Abstract: A semi-single frequency network (SFN) concept is presented. According to the SFN concept, the same data signal is transmitted from multiple base stations to a mobile terminal simultaneously on the same frequency band. Accordingly, the transmitted signals are combined in the radio channel and the mobile terminal experiences the transmitted signals as one signal propagated through a multipath channel. Additionally, each base station transmits a base station specific pilot signal. The mobile terminal carries out a channel estimation procedure for each received pilot signal and combines the channel estimates to obtain information how to equalize the received data signal. Then, the mobile terminal calculates equalization weights from the combined channel estimates and equalizes the received data signal.

Abstract: A timing adjustment value is received, and from the received timing adjustment value is determined an integer portion and a fractional portion. In the frequency domain, the determined fractional portion is applied by rotating a signal. Optionally, a phase shift may also be imposed with the rotation. In the time domain, the determined integer portion is applied by one of inserting samples in the rotated signal or removing samples from the rotated signal in an amount corresponding to the determined integer portion. After the signal rotation to apply the fractional portion, the active sub-carriers are mapped, and the transition from frequency domain to time domain occurs by means of an inverse Fourier transform. A cyclic prefix CP may be added after the Fourier transform, separately or functionally combined with the integer portion shift by modifying the size of the CP to impose the determined integer portion.

Abstract: Maximum diversity in multiple antenna distributed frequency broadband systems such as MIMO-OFDM is achievable through space-frequency (SF) and space-time-frequency (STF) coding. Full-rate full-diversity coding is achieved through a combination of maximal minimum product distance symbol set design and formation of codeword blocks. Full-diversity codes are also achieved which have reduced symbol transmission rates, such as through mapping of space-time (ST) codes to SF codes. The reduction in symbol rate may be offset by the fact that any ST code may be mapped to a full-diversity SF code.

Abstract: A timing adjustment value is received, and from the received timing adjustment value is determined an integer portion and a fractional portion. In the frequency domain, the determined fractional portion is applied by rotating a signal. Optionally, a phase shift may also be imposed with the rotation. In the time domain, the determined integer portion is applied by one of inserting samples in the rotated signal or removing samples from the rotated signal in an amount corresponding to the determined integer portion. After the signal rotation to apply the fractional portion, the active sub-carriers are mapped, and the transition from frequency domain to time domain occurs by means of an inverse Fourier transform. A cyclic prefix CP may be added after the Fourier transform, separately or functionally combined with the integer portion shift by modifying the size of the CP to impose the determined integer portion.

Abstract: A semi-single frequency network (SFN) concept is presented. According to the SFN concept, the same data signal is transmitted from multiple base stations to a mobile terminal simultaneously on the same frequency band. Accordingly, the transmitted signals are combined in the radio channel and the mobile terminal experiences the transmitted signals as one signal propagated through a multipath channel. Additionally, each base station transmits a base station specific pilot signal. The mobile terminal carries out a channel estimation procedure for each received pilot signal and combines the channel estimates to obtain information how to equalize the received data signal. Then, the mobile terminal calculates equalization weights from the combined channel estimates and equalizes the received data signal.