Systems and methods for a non-data-aided (NDA) approach to advanced OFDM timing are provided. This approach allows for accurate OFDM symbol timing and synchronization by avoiding inter-symbol interference (ISI) in multipath environments where an earliest arriving signal may not be the strongest signal. The NDA approach may rely on generating and applying a bias correction to a combined correlation result of the multi-path signals.

An operating method for an electronic device and a signal processor included in the electronic device are provided. The operating method for an electronic device comprises a descrambling a synchronization signal received from a cell, acquiring a time domain average signal on the descrambled synchronization signal, executing a differential correlation on the time domain average signal by a predetermined reference, and measuring a power of the synchronization signal provided from the cell, using the differential.

The present disclosure provides techniques for bandwidth constrained communication systems with frequency domain information processing. A bandwidth constrained equalized transport (BCET) communication system can include a transmitter, a communication channel, and a receiver. The transmitter can include a pulse-shaping filter that intentionally introduces memory into a signal in the form of inter-symbol interference, an error control code (ECC) encoder, a multidimensional fast Fourier transform (FFT) processing block that processes the signal in the frequency domain, and a first interleaver. The receiver can include an information-retrieving equalizer, a deinterleaver with an ECC decoder, and a second interleaver joined in an iterative ECC decoding loop. The communication system can be bandwidth constrained, and the signal can comprise an information rate that is higher than that of a communication system without intentional introduction of the memory at the transmitter.

Apparatus and associated methods relate to providing robust synchronization of a Radio-Frequency (RF) communication in a severe-fading environment. A first portion of a detected RF signal is auto-correlated with a second portion of the detected RF signal. The first and second portions are time-separated by the predetermined time delay separating the first and second code-sequences. A third portion of the detected RF signal is sync-correlated with a sync-sequence so as to generate a sync-correlation signal. The third portion is of the predetermined length of the sync sequence and includes the first and second portions of the detected RF signal used to generate the auto-correlation signal. The auto-correlation signal is multiplied by the sync-correlation signal so as to generate a combined synchronization signal. A peak in the combined synchronization signal is then detected. This peak can be indicative of a synchronization time of an authorized communication.

In one embodiment, an apparatus comprises: a baseband processor having a preamble generation circuit to generate a preamble for an orthogonal frequency division multiplexing (OFDM) transmission, the preamble generation circuit to generate the preamble having a first portion comprising a first plurality of symbols and a second portion comprising a second plurality of symbols, where the preamble generation circuit is to generate at least some of the second plurality of symbols having at least one frequency disruption between successive symbols of the second portion; a digital-to-analog converter (DAC) coupled to the baseband processor to convert the first plurality of symbols and the second plurality of symbols to analog signals; a mixer coupled to the DAC to upconvert the analog signals to radio frequency (RF) signals; and a power amplifier coupled to the mixer to amplify the RF signals.

A communication system is configured to generate a perturbed signal by perturbing an amplitude of a spectrum of an original signal in one or more spectral regions, and to propagate the perturbed signal through components of the communication system. The communication system is further configured to obtain a measurement of the perturbed signal in a first spectral region of the one or more spectral regions following the propagation of the perturbed signal, and to calculate an estimate of an impairment associated with the communication system based on the measurement.

Methods, systems, and devices for wireless communications are described. A user equipment (UE) may transmit, to a base station, a request for a data transmission that includes multiple subsets of data each associated with a different constellation granularity. In response to the request, the base station may encode the data transmission using multiple different constellation granularities and may transit the encoded data transmission to the UE. For example, the UE may receive the data transmission including a first subset of data that was encoded by the base station using a first constellation granularity and a second subset of data that was encoded by the base station using a second constellation granularity. The UE may then iteratively estimate phase-noises associated with respective subsets of data and perform phase-noise correction operations on the entire data transmission based on the estimated phase-noises.

In one embodiment, an apparatus includes: a radio frequency (RF) front end circuit to receive and downconvert a RF signal to a second frequency signal, the RF signal comprising an orthogonal frequency division multiplexing (OFDM) transmission; a digitizer coupled to the RF front end circuit to digitize the second frequency signal to a digital signal; and a baseband processor coupled to the digitizer to process the digital signal. The baseband circuit comprises a first circuit having a first plurality of correlators having an irregular comb structure, each of the first plurality of correlators associated with a carrier frequency offset and to calculate a first correlation on a first portion of a preamble of the OFDM transmission.

Phase noise estimation and cancellation as disclosed herein may allow cost-efficient increase of capacity in communications by enabling very high QAM levels. The proposed solution is potentially applicable to any single carrier applications where phase noise is a limiting factor and a required order of modulation is very high. For example, disclosed embodiments may enable high QAM levels for microwave backhauls despite severe phase noise sensitivity. One embodiment involves a pilot-aided and BCJR-based sequential search algorithm that accurately estimates and subtracts fast-varying phase noise symbol-by-symbol. Residual BER performance is evaluated under the most challenging phase noise scenarios. FPGA emulation results show detection and removal of a significant amount of phase noise and zero BER performance even for complex 1K-QAM and above.

Techniques are disclosed relating to detection of wireless signals. In some embodiments, a method includes generating an autocorrelation result for a training field in a received wireless message, generating differentiation information based on the autocorrelation result, and determining that one or more signal recognition criteria are met. In some embodiments, the signal recognition criteria include a first criterion that a first peak in the differentiation information satisfies a first threshold for at least a first time interval. In some embodiments, the signal recognition criteria include one or more additional criteria, including a second criterion that a second peak in the differentiation information satisfies a second threshold for at least a second time interval, wherein the first and second peaks have different polarities and/or a third criterion that the first peak corresponds to an autocorrelation result value that is below a particular autocorrelation threshold.