Wireless communication networks may use various techniques, including those that use multiple-access techniques such as multi-user multiple-input multiple-output (MU-MIMO) techniques. In some embodiments, the use of a MU-MIMO setup frame may give a destination STA a chance to select a best antenna weight vector (AWV) based on previous antenna training. In particular, the use of an AWVgroupID may be used to identify a group of one or more STAs that can be the destination STAs of the MU-MIMO setup frame.

WTRUs, access points (APs) and methods thereon are disclosed. A method on a WTRU may include receiving a message from an AP that comprises a beamformee capability element; sending a second message to the AP that comprises a beamformer capability element; and receiving, from the AP, a third message in response to the second message that indicates a group to which the WTRU is assigned. The group may be based on the beamformer capability element and the group may indicate UL transmission information to be used by the WTRU. A method on an AP may include determining a group for multiple WTRUs based on a received beamformer capability element. A method on a WTRU may include sending to an AP a message with a low overhead preamble for UL MU-MIMO. The low overhead preamble may include LTFs that enable the AP to distinguish the WTRU from other WTRUs.

An antenna system of a satellite may consist of an antenna receiver that is coupled to a plurality of flexible couplings. The couplings may each be affixed to one or more antenna elements. The couplings may be deployed in space in an uncontrolled manner. Additionally, the spacing between the couplings, and in turn the antenna elements, may be spaced in an uncontrolled manner. The antenna elements may have no pointing requirements. The antenna system may receive training signals and associate an antenna element to a time of arrival based on the training signal. Upon receiving a data signal, the antenna system may apply coefficients determined from the association of the antenna element to the time of arrival to the data signal to discover wanted signal coherence among the antenna elements.

A communication apparatus includes a circuitry and a transmitter. In operation, the circuitry generates a Demodulation Reference Signal (DMRS) and generates downlink control information indicating a mapping pattern of the DMRS from a plurality of mapping patterns, and the transmitter transmits the DMRS and the downlink control information. The plurality of mapping patterns include a first mapping pattern and a second mapping pattern. Resource elements used for the DMRS of the second mapping pattern are same as a part of resource elements used for the DMRS of the first mapping pattern. A number of the resource elements used for the DMRS of the first mapping pattern is larger than a number of the resource elements used for the DMRS of the second mapping pattern.

A method of receiving a signal by a receiver in a mobile communication system is provided. The method includes: receiving a reference signal from a transmitter; determining first channel information based on the received reference signal; receiving a data signal based on the first channel information; and determining second channel information based on the received data signal and the first channel information. Iterative channel estimation is performed to reduce channel estimation errors by determining errors of signals received from a turbo decoding unit and using symbol information as pilots even in subcarriers where the pilot signals are not transmitted, and to increase the accuracy of LLR calculation through an iteration process such as a detection and decoding process in comparison with the conventional technology, thereby increasing the reception performance of the turbo decoding unit and improving communication efficiency.

Provided is a communication system achieving favorable beamforming training even in an environment where multiple wireless communication networks adjacently exist. In this communication system, in an RXSS, an STA measures received signal qualities of respective first training frames received from an AP and ranks the received signal qualities. In a TXSS following the RXSS, the STA measures received signal qualities of respective third training frames received from the AP and ranks the received signal qualities. The STA transmits fourth training frames respectively including the measured received signal qualities of the third training frames based on the ranks of the received signal qualities of the first training frames.

A reception unit in a radio communication apparatus receives wirelessly a signal configured with a preamble from another radio communication apparatus. The synchronization detection unit uses the preamble included in the signal received by the reception unit to detect synchronization with another radio communication apparatus. The signal accumulation unit accumulates a signal extracted from the signal received by the reception unit based on a timing at which the synchronization is detected by the synchronization detection unit. The combining unit combines the signals accumulated in the signal accumulation unit in accordance with a blind adaptive array antenna algorithm. The demodulation unit demodulates the signals combined by the combining unit.

Embodiments can include receiving transmissions over a channel at a receiver of a MIMO communication system; the transmissions are received from a plurality of transmitters in communication with the receiver. Each communication is a separate communication having a modulation and coding scheme. An estimate of the channel is converted into an estimate, for each of a plurality of transmitters, of a bit-metric decoding rate for each of a plurality of MIMO detectors. The estimated bit-metric decoding rate for each of the transmitters for each of the MIMO detectors is converted into an estimated bit error rate for each of the MIMO detectors for each of the transmitters. One of the MIMO detectors is selected for use in generating log-likelihood ratios for bits transmitted from the transmitters to the receiver. The one of the MIMO detectors is selected based on the estimated bit-error rates and a target block error rate.

Presently disclosed are systems and methods for beamforming training in WLANs. In various embodiments, there are unified MIMO beamforming training procedure, which includes a training period in which an initiator transmits multiple unified training frames for performing a transmit-beamforming training of the initiator and a receive-beamforming training of one or more responders; a feedback period in which each responder replies with a beamforming-feedback response; and an acknowledgement period during which the initiator transmits respective acknowledgement frames to the one or more responders from which responses were received. Rules for restricted random access in various slots of the feedback period may be implemented, to address response contention between multiple qualifying responders.

An apparatus and a method for configuring antenna arrays for scalable radio frequency (RF) architecture are dis-closed. A subset of antenna arrays are grouped into K groups and a receive or transmit weight vector is applied to each of the antenna arrays in each of the K groups. A channel response is measured for each of the antenna in the K groups. The response is summed for each group and complex scaling factors are calculated based on the summed response. Based on the scaling factors the antenna weight vectors arc updated and the updated weight vectors arc applied to the antenna arrays. The steps of grouping the antennas and refining the weight vectors are performed till the antenna weight vectors reach a steady point, i.e. the current antenna weight does not improve the beamforming gain by a predetermined threshold in comparison to the previous antenna weight.