A broadcasting signal transmitting apparatus that transmits a plurality of signals through a plurality of antennas to increase a data transmission rate. The broadcasting signal transmitting apparatus includes a signal generator configured to generate the plurality of signals each of which includes at least one preamble symbol and data symbols, a frequency allocator configured to allocate a first subcarrier position of a whole frequency to a first preamble symbol included in a first signal among the plurality of signals and to allocate, by shifting a frequency position of the first subcarrier position by a preset interval, a second subcarrier position to a second preamble symbol included in a second signal among the plurality of signals, and a transmitter configured to transmit the plurality of signals through the plurality of antennas. The antennas respectively correspond to subcarrier positions allocated to the plurality of signals.

Methods and apparatus for orthogonal stream spatial multiplexing. In one embodiment, a method includes splitting and modulating a data stream into n MIMO RF spatial streams and coupling them to corresponding switchable polarization antenna elements controlled via orthogonal binary codes for transmission. Each transmitted stream manifests as time-varying-polarization-orthogonal to the other n−1 spatial streams. The method includes reception of the streams at their destination using corresponding antenna elements controlled by the same set of orthogonal codes. Thus, each of the n transmitted spatial streams is polarization-match-filtered, unambiguously separated and individually recovered from all the others upon reception for subsequent demodulation and MIMO spatial recombination into the original data stream. Thus, n MIMO spatial streams emanating from a common source and featuring equal amplitude and bandwidth but bearing distinct data and exhibiting mutually orthogonal time varying polarization will propagate mutually interference-free on the same frequency channel to a single destination.

A communication apparatus of the present disclosure includes a receiver which, in operation, receives a signal that includes a non-legacy preamble and a data field, the non-legacy preamble comprising a first field for indicating a number of spatial streams (Nss) in the data field and a second field for indicating one of a plurality of modulation and coding schemes (MCSs), wherein two or more frequency diversity transmission schemes are supported and one of the two or more frequency diversity transmission schemes is applied based on a value of the Nss; and circuitry which, in operation, decodes the signal.

Spatial multiplexing and transmit diversity can improve the capacity of a wireless communication system. The system and method adapts communication schemes for communication systems with multiple antennas utilizing at least two transmission modes. The at least two transmission modes can, but are not necessarily, used for uplink communications. The two transmission modes may be chosen from the group consisting of a single antenna mode, a diversity mode a spatial multiplexed mode and a mixed diversity and spatial multiplexed mode. The at least two transmission modes may involve adaptation among multiple transmitters. At least one receiver may indicate a transmission mode to be used by a transmitter for a subsequent transmission. A transmitter may determine a transmission mode to be used for a subsequent transmission. The transmission mode can be based on channel sounding.

Disclosed is a method for transmitting a downlink pilot, which serves to solve the problem that the power of Orthogonal Frequency Division Multiplexing (OFDM) symbols is different due to Walsh codes. The method includes: transmitting a dedicated pilot in the Code Division Multiplexing (CDM) approach or in the combination approach of CDM and Frequency Division Multiplexing (FDM); further, in the resources for transmitting the dedicated pilot, configuring an orthogonal resources for the dedicated pilot according to a set mapping rule.

Systems and methods for interference and/or power reduction for multiple relay pairs using cooperative beamforming are provided. A method of operation of a network node in a cellular communications system includes determining beamforming weights for multiple of subchannels for each of multiple relay nodes such that a parameter is minimized. The parameter is a maximum per subchannel interference and/or per relay power usage. Determining the beamforming weights includes determining a dual problem of the minimization of the parameter where a solution maximizing the dual problem will minimize the parameter; reformulating the dual problem into a semidefinite programming (SDP) problem; and determining if signal-to-noise ratio (SNR) constraints are active. If the SNR constraints are all active, the method includes determining optimal beamforming weights a first way and if the SNR constraints are not all active, determining optimal beamforming weights a second way. In some embodiments, the performance of relays is improved.

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.

Embodiments of a method in a base station configured to transmit and receive wireless signals to and from a user equipment, UE. A downlink channel response of a first UE antenna is determined, based on uplink signals received from the UE. First preceding weights are calculated based on the determined channel response of the first UE antenna Orthogonal or quasi-orthogonal preceding weights are determined based on the first preceding weights. First and second downlink signal layers are transmitted using the first preceding weights and the orthogonal or quasi-orthogonal preceding weights.

An apparatus and method are provided for a quantity and size of subbands in a channel state information (CSI) reporting band for flexibility and reduced complexity of terminal addressing. The method includes: determining a channel state information subband size based on a bandwidth part (BWP), determining a quantity of channel state information subbands included in a channel state information reporting band based on (i) a carrier bandwidth (CC bandwidth), (ii) the BWP bandwidth or (iii) a channel state information reference signal (CSI-RS) bandwidth and the channel state information subband size. The method further includes determining an actual quantity of resource blocks included in a starting subband and an actual quantity of resource blocks in an ending subband in the channel state information subband.

In order to cancel any interference due to the second signal (e.g., from a non-serving cell) from a signal received at a UE, without receiving additional control information, the UE blindly estimates parameters associated with decoding the second signal. This may include determining a metric based on sets of symbols associated with the signals in order to determine parameters for the second signal, e.g., the transmission mode, modulation format, and/or spatial scheme of the second signal. The parameters for the signal may be determined based on a comparison of the metric with a threshold. When a spatial scheme and a modulation format is unknown, the blind estimation may include determining a plurality of constellations of possible transmitted modulated symbols associated with a potential spatial scheme and modulation format combination. Interference cancellation can be performed using the constellations and a corresponding probability weight.