In a transmitter apparatus, a known reference signal is superimposed on top of a data signal that is typically not known a priori to a receiver and the combined signal is transmitted. At a receiver, an iterative channel estimation and equalization technique is used to recover the reference signal and the unknown data signal. In the initial iteration, the known reference signal is recovered by treating the data signal as noise. Subsequent iterations are used to improve estimation of received reference signal and the unknown data signal.

An operating method of a communication device for providing a beamformed transmission signal to a plurality of terminals may include determining a target transmission vector based on an area restriction condition for each of the plurality of terminals, generating a beam selection matrix for selecting some of a plurality of antennas based on the target transmission vector and a beam selection condition, generating a precoding matrix based on the target transmission vector and the beam selection matrix, and generating a transmission signal based on the beam selection matrix and the precoding matrix.

Disclosed is a transmission scheme for transmitting a first modulated signal and a second modulated signal over the same frequency at the same time. According to the transmission scheme, a precoding weight multiplying unit multiplies a baseband signal after a first mapping and a baseband signal after a second mapping by a precoding weight and outputs the first modulated signal and the second modulated signal. In the precoding weight multiplying unit, precoding weights are regularly hopped.

This invention presents a repeater enhanced MU-MIMO wireless communication system comprising a BS, a plural of repeaters, and a plural of UEs, where a repeater estimates the channel between itself and its upper communication node in the system, a repeater computes equalization coefficients based on the estimation of the channel coefficients, and a repeater applies the equalization coefficients to reduce the channel delay spread or increase the coherence bandwidth of the channel between communication nodes containing the BS, the UEs, or the repeaters.

Systems and methods for enabling precoding diversity in the time domain are provided. In some embodiments, a User Equipment (UE) includes circuitry including a processing module and a memory module configured to receive an indication that a physical channel is repeated over a set of subframes and receive an indication that the UE can assume that a first subset of the repetitions of the physical channel and a reference signal will use a first precoder. In this way, in some embodiments, the UE can coherently combine the repetitions, including the reference signals used by the physical channel. The ability to coherently combine repetitions of the physical channel may improve both the estimates of the physical channel as well as channel estimates derived from the repeated reference signals.

A receiving device includes an equalization processor including multiple delay equalizers. The equalization processor is configured to: obtain a first error between an output of one specific tap in the multiple delay equalizers and a predetermined reference value, and calculate a first weight with which the first error is minimized; cause a calculation result of the first weight to be reflected in all taps in the multiple delay equalizers except the specific tap, obtain a second error between outputs of all taps in the multiple delay equalizers and the predetermined reference value, and calculate a second weight with which the second error is minimized; and update coefficients of all taps in the multiple delay equalizers at the same timing using the calculation result of the first weight and a calculation result of the second weight, and calculate an output of the equalization processor.

Systems and methods for enabling precoding diversity in the time domain are provided. In some embodiments, a User Equipment (UE) includes circuitry including a processing module and a memory module configured to receive an indication that a physical channel is repeated over a set of subframes and receive an indication that the UE can assume that a first subset of the repetitions of the physical channel and a reference signal will use a first precoder. In this way, in some embodiments, the UE can coherently combine the repetitions, including the reference signals used by the physical channel. The ability to coherently combine repetitions of the physical channel may improve both the estimates of the physical channel as well as channel estimates derived from the repeated reference signals.

Disclosed is a transmission scheme for transmitting a first modulated signal and a second modulated signal over the same frequency at the same time. According to the transmission scheme, a precoding weight multiplying unit multiplies a baseband signal after a first mapping and a baseband signal after a second mapping by a precoding weight and outputs the first modulated signal and the second modulated signal. In the precoding weight multiplying unit, precoding weights are regularly hopped.

A system and method are described which enable planned evolution and obsolescence of multiuser wireless spectrum. One embodiment of such a system includes one or multiple centralized processors and one or multiple distributed nodes that communicate via wireline or wireless connections. The distributed nodes may share their identification number and other reconfigurable system parameters with the centralized processor. The information about all distributed nodes may be stored in a database that is shared by all centralized processors. The reconfigurable system parameters may comprise power emission, frequency band, modulation/coding scheme. The distributed nodes may be software defined radios such as FPGA, DSP, GPU and/or GPCPU that run algorithms for baseband signal processing and may be reconfigured remotely by the centralized processor. A cloud wireless system may be used wherein the distributed nodes are reconfigured periodically or instantly to adjust to the evolving wireless architecture.

Methods for improving multiple signal reception using receiver diversity in the context of a wideband radar and communications receiver. The method allows for improved signal reception as well as improved angle of arrival estimation. A first approach uses a method that improves angle of arrival estimation while using the standard diversity technique of selection combining. A second approach uses a method of equalization of the signal rather than equalization of the channel to both improve the signal SNR over standard selection combining and further improve the angle of arrival estimate over the first approach.