Optical transmitters and receivers for improving synchronization of data transmitted over an optical network are described. The receiver can perform non-linear filtering as part of framer index estimation operations to improve the synchronization. The receiver can determine estimated positions of framer indices in data frames received from the transmitter. Next, using a non-linear filter, the receiver can remove estimated positions that are likely erroneous or are greater than a threshold away from the median or mode estimated framer index position. By removing the likely erroneous estimated positions, the receiver can then determine the estimated position of a framer index position for multiple frames with greater confidence.

The gains with non-orthogonal multiple access (NOMA) for uplink data transmissions can be high when chosen codes are orthogonal. However, when codes are non-orthogonal, the gains can be low. NOMA can be used when there is more than one mobile device using the same resources. Since orthogonal codes cannot be possible for every length, codes which have low cross-correlation properties can be used. However, when there are a large number of mobile devices using the same resources, the cross-correlation between the codes can cause interference to the mobile devices. Reducing the gains of a NOMA system can reduce the overall throughput. Thus, transmitting data on the same resources in a NOMA can occur in spite of the interference to the UEs transmitting data on the same resources. Therefore, a non-orthogonal multiple access design for a 5G network can mitigate interference.

Methods, a Base Station (BS), and a User Equipment (UE) in a wireless communication system for transmitting and receiving control information are provided. The method for transmitting control information by a BS in a wireless communication system includes receiving information related to a signal transmitted by a second BS that the second BS which is a neighboring BS of the first BS, determining whether a second UE using an identical resource to that used by a first UE included in a cell of the first BS exists within a cell of the second BS based on the received information, when the second UE exists, generating control information for controlling a signal transmitted to the second UE by the second BS based on the received information, and transmitting the generated control information to the first UE through a control channel.

Systems, methods, and devices enable coexistence of traffic for collocated transceivers. Methods may include transmitting a baseband training signal via a transmit path of a wireless communications device, obtaining a plurality of samples of the baseband training signal via a receive path of the wireless communications device, and generating a plurality of weighted averages based on the plurality of samples. Methods may further include generating an estimated amplitude and an estimated phase for at least one spur frequency of the wireless communications device based, at least in part, on the plurality of weighted averages.

Methods, a Base Station (BS), and a User Equipment (UE) in a wireless communication system for transmitting and receiving control information are provided. The method for transmitting control information by a BS in a wireless communication system includes receiving information related to a signal transmitted by a second BS that the second BS which is a neighboring BS of the first BS, determining whether a second UE using an identical resource to that used by a first UE included in a cell of the first BS exists within a cell of the second BS based on the received information, when the second UE exists, generating control information for controlling a signal transmitted to the second UE by the second BS based on the received information, and transmitting the generated control information to the first UE through a control channel.

A device is configured to calculate a set of channel estimates for a plurality of sub-carriers based on a plurality of pilot-symbols and/or data-symbols carried by said plurality of sub-carriers; calculate a set of equalizers for the plurality of sub-carriers based on the set of channel estimates; perform an equalization on a plurality of data-symbols using the set of equalizers for obtaining a plurality of equalized symbols; perform a soft-slicing or hard-slicing procedure comprising obtaining a plurality of estimated symbols based on the equalized symbols; calculate at least one diagonal-loaded interference-plus-noise covariance matrix, based on the set of estimated symbols; de-map the plurality of data symbols to soft-bits, based on the at least one diagonal-loaded interference-plus-noise covariance matrix, the set of channel estimates or an updated version thereof; and feed the soft-bits to a channel decoder.

Secure channel training to enhance the confidentiality level of a power domain non-orthogonal multiple access (NOMA) communication system when impaired by eavesdropping attacks coming from inside and outside of the network. In a first scenario, a cooperative jammer available in the system defines an external source of entropy that is independent of the channel variation rate. While the jammer provides secrecy inside the network, the proposed invention is configured to secure the network from outside, encoding the system information, which is exchanged during the training phase, using only the channel state. In a second scenario, the cooperative jammer is not available; with the secrecy inside and outside of the network ensured through a different parameterization. That parameterization is done in a way that the required system information is encoded using not only the channels, but also a random phase defined in the data communication phase.

A radio apparatus capable of reducing the amount of calculation required to suppress an interference signal is provided. A radio apparatus (1) includes a spatial transformation unit (2) configured to perform a spatial transformation on a received signal including a desired signal and an interference signal received by a plurality of antennas, and thereby calculate a first beam-space received signal vector, a beam selecting unit (3) configured to select at least two elements from the first beam-space received signal vector and generate a second beam-space received signal vector, and an interference suppression synthesis unit (4) configured to estimate a covariance matrix of an interference noise signal including a noise signal and the interference signal included in the second beam-space received signal vector, generate a reception weight by using this covariance matrix, and detect the desired signal based on the reception weight and the second beam-space received signal vector.

Joint estimation of the framer index and the frequency offset in an optical communication system are described among various other features. A transmitter can transmit data frames using pilot and framer symbols. A receiver can estimate the framer index and frequency offset using the pilot and framer symbols, and identify the beginning of a header portion of a data frame. By identifying the beginning of the header portion of a data frame, the receiver can then process data received from the transmitter in a manner synchronous to the manner in which the data was transmitted by the transmitter.

Systems, methods, and devices reduce and mitigate spurs that may occur in transmit waveforms of wireless communications devices. Methods include receiving a plurality of samples of a baseband transmission and generating, using a processing device, an estimated amplitude and an estimated phase of a spur component of the baseband transmission based on the received plurality of samples, the spur component being a spectral spike in a transmit waveform. Methods further include generating, using the processing device, a canceling signal configured to cancel the estimated amplitude and estimated phase of the spur component, and canceling the spur component of the baseband transmission by combining the canceling signal with a transmission of at least a portion of a data packet.