Abstract: A method and system are described for improving operating efficiency and QoS in a cellular communications network. According to an exemplary embodiment, the method includes predicting background interference levels due at least partly to signals generated in neighboring cells, and transmitting operating parameters to user equipment that include power, frequency, and/or spectral efficiency parameters. The operating parameters are selected according to the predicted background interference to provide acceptable quality of service while also optimizing use of available bandwidth. The method further includes updating the background interference predictions, and transmitting revised operating parameters to the user equipment according to rules that minimize changes to operating parameters that strongly affect background interference in neighboring cells, such as power levels and frequencies, thereby minimizing background interference fluctuations.

Abstract: Methods and systems are described for calibrating phase hardware-induced distortion in a cellular communications system. In one aspect, an estimate of a phase difference at a user equipment (UE) between downlink channels including signals sent over two or more BS transmitter chains is obtained. A phase difference between uplink channels including signals received over two or more BS receiver chains is determined. A relative phase distortion induced by two or more BS transceiver chains is determined based on the received estimate of phase difference between downlink channels and the determined phase difference between uplink channels.

Abstract: Methods and systems for determining scheduling information of a base station in a network operating according to the Long Term Evolution (“LTE”) standard include monitoring transmissions on the PDCCH of the wireless base station, maintaining a list of active Radio Network Temporary Identifiers (“RNTI's”) assigned by the wireless base station to user equipment, extracting PDCCH detections from the monitored transmissions, applying at least one false alarm reduction strategy to eliminate invalid PDCCH detections from the extracted PDCCH detections, said false alarm reduction strategy including determining an RNTI that is valid for an extracted PDCCH detection and determining if the valid RNTI is included in the list of active RNTI's. Scheduling information of the wireless base station is determined from the extracted PDCCH detection.

Abstract: An improved receiver design implements a method for modeling users in SIC turbo loop multiuser detection architectures that reduces the number of implementation cycles, and thereby reduces the computational overhead associated with computing the inverse of the received signal covariance matrix, by efficiently reusing components of a QR decomposition. By reusing some of the computational results from the previous turbo loop's equalizer calculation, the disclosed receiver significantly reduces the computational burden of updating the linear equalizer on each turbo loop. Depending on the embodiment, this reduction can be accomplished in at least two different ways, depending on the dimensionality and other aspects of the implementation.

Abstract: Methods and systems for obtaining improved joint channel estimates for a multi-user, frequency-multiplexed data transmission such as SC-FDMA or OFDM begins by estimating separate contributions of users (and/or other signal sources) to the received signal based on joint frequency domain channel estimates. A reduced data set is obtained by subtracting contributions of one or more users from the received data, leaving only the estimated contributions of the remaining users, with noise and residual estimation error signal. Time domain joint channel estimation is then performed on the reduced data set, which is feasible because the number of users has been reduced. In exemplary embodiments, the reduced data set includes only one estimated user contribution. This process is repeated to obtain time domain estimates for all of the users. The method can be repeated by using the TD channel estimates to re-estimate the user contributions and calculate revised TD channel estimates.

Abstract: A method is disclosed for increasing the communication capacity of a shared ad-hoc wireless channel by using multiuser detection (MUD) to distinguish overlapping information transmitted simultaneously by a plurality of nodes. The transmitting nodes simultaneously provide parameter-estimating signals over separate, unshared, low-rate parameter channels generated using orthogonal frequencies, spread spectrum technology, or time multiplexing. Receiving nodes use these separate, non-overlapping parameter-estimating signals to estimate MUD-required signal parameters such as amplitude, phase, and frequency offset, thereby enabling use of lower complexity MUD receivers, because the parameters are not estimated in the presence of other interference. Node ID, spreading code type, and/or other information can also be transmitted over the parameter channels. Limiting the number of parameter channels can limit the maximum number of transmitting nodes.

Abstract: Methods and systems are described for adaptive channel estimation and equalization in a multicarrier communication system. In one aspect, a channel estimation in a multicarrier communication system is determined. A prediction error is determined based on a difference between the channel estimation and a reference signal. An equalization matrix is formed based on the prediction error.

Abstract: A method and apparatus are disclosed that apply multiuser detection (MUD) analysis to an aggregated RF response from a plurality of simultaneously queried RFID tags, so as to distinguish the individual tag responses. The claimed method thereby significantly reduces RFID detection latency when multiple tags are simultaneously queried. Some embodiments transmit carrier waves at more than one frequency, such as a plurality of equally-spaced frequencies, so as to enhance the MUD analysis by incorporating a multi-frequency dimension. Other embodiments incorporate additional spatial dimensions by deploying multiple RF detection antennae at separated locations. The number of colliding tag responses must be estimated before MUD analysis can be applied.

Abstract: Methods and systems for performing compressed time domain joint channel estimation in a multi-user MIMO LTE wireless network include receiving training signals from a plurality of users, estimating a maximum delay spread for the received data according to a coherence bandwidth of the received data, limiting the received data in the time domain to the estimated maximum delay spread, selecting and estimating an active tap from the limited data set, and subtracting a contribution of the selected active tap from the reduced data set. These steps can be repeated until the residual signal falls below a specified minimum. The network can be a C-RAN network. The training data can be SRS or DMRS data. Limiting the received data ensures that only a few significant taps are analyzed, so that the system is not under determined and can be analyzed for accurate channel estimation using any of several existing algorithms.

Abstract: Methods and systems are described for parameter estimation based on historical context information. In one aspect, a communication context for a first mobile device is determined. The communication context is compared to a stored historical communication context of at least one other mobile device, wherein the stored historical communication context includes at least one of communication parameter estimates, mobile device statistics, mobile device transmit settings, and base station receiver settings. Parameters for communicating with the first mobile device are estimated based on the comparison.

Abstract: Methods and systems are described for determining a Demodulation Reference Sequence (DMRS) for an intercell interfering signal received from a mobile device in a Long Term Evolution (LTE) communication system. In one aspect, an interfering signal transmitted from a mobile device being served by a second cell of an LTE communication system is received at a receiver serving a first cell in the LTE communication system. At least one transmit parameter is detected from the received interfering signal. A DMRS for the received interfering signal is determined based on the detected transmit parameter.

Abstract: Methods and systems are described for calibrating amplitude hardware-induced distortion in a long term evolution (LTE) communications system. In one aspect, a power status indication is received at a base station (BS) associated with a centralized radio access network (C-RAN) of an LTE communications system from a user equipment (UE) communicating in the LTE communications system. A downlink pathloss associated with communications to the UE is estimated based on the received power status indication. Downlink power allocation is performed at the C-RAN based on the downlink pathloss estimates of one or more UEs.

Abstract: Methods and systems are described for communicating data selectively via heterogeneous communication network links. In one aspect, a network link selector (NLS) determines respective data costs associated with communicating data via a plurality of heterogeneous network links each linking to one or more networks. One or more network links to communicate data between a remote network node and a user device remotely communicating with the NLS via a network is selected from among the plurality of heterogeneous network links based on the determined respective data costs. Communicating the data via the selected link is provided for. In another aspect, link selection information based on respective data costs is received via a network from an NLS. One or more network links is selected from among the plurality of heterogeneous network links based on the received link selection information. The data is communicated via the selected link.

Abstract: Methods and systems for determining scheduling information of a base station in a network operating according to the Long Term Evolution (“LTE”) standard include monitoring transmissions on the PDCCH of the wireless base station, maintaining a list of active Radio Network Temporary Identifiers (“RNTI's”) assigned by the wireless base station to user equipment, extracting PDCCH detections from the monitored transmissions, applying at least one false alarm reduction strategy to eliminate invalid PDCCH detections from the extracted PDCCH detections, said false alarm reduction strategy including determining an RNTI that is valid for an extracted PDCCH detection and determining if the valid RNTI is included in the list of active RNTI's. Scheduling information of the wireless base station is determined from the extracted PDCCH detection.

Abstract: An improved receiver design implements a practical method for modeling users in SIC turbo loop multiuser detection architectures, wherein in each loop unsubtracted estimation errors from previous loops are used to appropriately scale the error covariance matrix for each user, thereby accurately representing the remaining residual interference in the data stream for each desired user. The effect of estimation errors in previous interference cancellation operations is thereby minimized, and symbol estimations in successive turbo loops are improved, for example during multiuser MMSE, multiuser MMSE with interference rejection combining (MMSE-IRC), sample matrix inversion (SMI), or any of their adaptive variants (least mean-square, recursive least square, Kalman filter etc.). The estimated residual symbol energy can be computed per symbol, and then applied to entire data streams, to groups of symbols, or to each symbol separately.

Abstract: Methods and systems for obtaining improved joint channel estimates for a multi-user, frequency-multiplexed data transmission such as SC-FDMA or OFDM begins by estimating separate contributions of users (and/or other signal sources) to the received signal based on joint frequency domain channel estimates. A reduced data set is obtained by subtracting contributions of one or more users from the received data, leaving only the estimated contributions of the remaining users, with noise and residual estimation error signal. Time domain joint channel estimation is then performed on the reduced data set, which is feasible because the number of users has been reduced. In exemplary embodiments, the reduced data set includes only one estimated user contribution. This process is repeated to obtain time domain estimates for all of the users. The method can be repeated by using the TD channel estimates to re-estimate the user contributions and calculate revised TD channel estimates.

Abstract: Methods and systems are described for calibrating phase hardware-induced distortion in a long term evolution (LTE) communications system. In one aspect, an estimate of a phase difference at a user equipment (UE) between downlink channels including signals sent over two or more BS transmitter chains is received from the UE in an LTE communications system. A phase difference between uplink channels including signals received over two or more BS receiver chains is determined at a BS. A relative phase distortion induced by two or more BS transceiver chains is determined based on the received estimate of phase difference between downlink channels and the determined phase difference between uplink channels.

Abstract: Methods and systems are described for providing a rapidly self-organizing cellular communications network. In one aspect, scheduling information is received for at least one mobile device previously scheduled for communication in a first cell of a cellular communications network, the scheduling information corresponding to a scheduling decision made for the first cell without the knowledge of scheduling decisions made for a second cell adjacent to the first cell. Whether to initiate a handover procedure to handover the mobile device to the first cell is determined based on the received scheduling information. The mobile device for is scheduled for communications in the second cell and/or the handover procedure is initiated based on the determination.

Abstract: Methods and systems for applying a multi-path, maximum SINR, pre-processing interference rejection filter to an interference-limited signal received from a plurality of users in a wireless network operating according to the Long Term Evolution (“LTE”) standard includes receiving raw data, including training data from a plurality of users, selecting at least one modeled user, subtracting a contribution of the modeled user(s) from the training data to form a residual training signal, forming an interference rejection covariance matrix from the residual training signal, whitening the raw data using the interference rejection covariance matrix, and equalizing the whitened received data. In embodiments, an estimated contribution of a subset of the modeled users is subtracted from the raw data for filtering in a subsequent turbo loop. The subset can be selected based on an estimated post-combined SINR, an estimated outage capacity, or an estimated multiuser efficiency of the received data.

Abstract: Methods and systems are described for providing a rapidly self-organizing cellular communications network. In one aspect, scheduling information is received for at least one mobile device previously scheduled for communication in a first cell of a cellular communications network, the scheduling information corresponding to a scheduling decision made for the first cell without the knowledge of scheduling decisions made for a second cell adjacent to the first cell. At least one parameter is determined, based on the received scheduling information, for communications in the second cell that improves performance of the first cell. Communications with mobile devices served by the second cell are adjusted based on the determined at least one parameter.