Transmission quality is improved in an environment in which direct waves dominate in a transmission method for transmitting a plurality of modulated signals from a plurality of antennas at the same time. All data symbols used in data transmission of a modulated signal are precoded by hopping between precoding matrices so that the precoding matrix used to precode each data symbol and the precoding matrices used to precode data symbols that are adjacent to the data symbol in the frequency domain and the time domain all differ. A modulated signal with such data symbols arranged therein is transmitted.

Transmission quality is improved in an environment in which direct waves dominate in a transmission method for transmitting a plurality of modulated signals from a plurality of antennas at the same time. All data symbols used in data transmission of a modulated signal are precoded by hopping between precoding matrices so that the precoding matrix used to precode each data symbol and the precoding matrices used to precode data symbols that are adjacent to the data symbol in the frequency domain and the time domain all differ. A modulated signal with such data symbols arranged therein is transmitted.

Disclosed is a precoding method for generating, from a plurality of baseband signals, a plurality of precoded signals that are transmitted in the same frequency bandwidth at the same time. According to the precoding method, one matrix is selected from among matrices defining a precoding process that is performed on the plurality of baseband signals by hopping between the matrices. A first baseband signal and a second baseband signal relating to a first coded block and a second coded block generated by using a predetermined error correction block coding scheme satisfy a given condition.

Methods, systems, and devices for wireless communications are described in which different spreading sequences may be used to distinguish concurrent non-orthogonal multiple access (NOMA) transmissions. The spreading sequences may be selected based on one or more codebooks configured at a user equipment (UE) and a codebook for an uplink NOMA transmission determined based on a set of common resources allocated for the uplink NOMA transmission and a number of expected transmitters in a transmitter group. The UE may identify data to transmit in the uplink NOMA transmission, apply the spreading sequence to the data, and transmit the spread data in the uplink NOMA transmission. A base station may receive multiple concurrent uplink NOMA transmissions, perform receive signal processing to identify spreading signals and UE identity, de-spread the signals based on different spreading sequences, and demodulate and decode the de-spread signals of the NOMA UE.

A method (10) performed in a network node (2) for selecting a codebook is provided. The network node (2) supports a multiple antenna communication mode for communication with a communication device (3). The method (10) comprises measuring (11) received power of a signal from the communication device (3), and selecting (12), based at least on the received power, one of: a first codebook adapted for a coverage limited scenario and a second codebook adapted for an interference limited scenario, for use in codebook based precoding in uplink. A corresponding method (40) in a communication device (3), a network node (2), communication device (3), computer programs and computer program products are also provided.

Provided is a precoding method for generating, from a plurality of baseband signals, a plurality of precoded signals to be transmitted over the same frequency bandwidth at the same time, including the steps of selecting a matrix F[i] from among N matrices, which define precoding performed on the plurality of baseband signals, while switching between the N matrices, i being an integer from 0 to N?1, and N being an integer at least two, generating a first precoded signal z1 and a second precoded signal z2, generating a first encoded block and a second encoded block using a predetermined error correction block encoding method, generating a baseband signal with M symbols from the first encoded block and a baseband signal with M symbols the second encoded block, and precoding a combination of the generated baseband signals to generate a precoded signal having M slots.

A method and apparatus for transmitting using beam are disclosed. A wireless transmit/receive unit (WTRU) may transmit a first physical random access channel (PRACH) preamble to a base station using a first beam at a first power level. The WTRU may receive an indication that the first PRACH preamble was received by the base station. If the indication was received, the WTRU may transmit data. If the indication was not received, the WTRU may select the first beam or a second beam to use for a second PRACH preamble. Further, the first and second beams may be different beams. If the first beam is selected, the WTRU may increase a transmission power level of the second PRACH preamble by a first power ramp step. If the second beam is selected, the WTRU may not increase the transmission power level of the second PRACH preamble by the first power ramp step.

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

Transmission quality is improved in an environment in which direct waves dominate in a transmission method for transmitting a plurality of modulated signals from a plurality of antennas at the same time. All data symbols used in data transmission of a modulated signal are precoded by hopping between precoding matrices so that the precoding matrix used to precode each data symbol and the precoding matrices used to precode data symbols that are adjacent to the data symbol in the frequency domain and the time domain all differ. A modulated signal with such data symbols arranged therein is transmitted.

A method for generating a codebook includes applying a unitary rotation to a baseline multidimensional constellation to produce a multidimensional mother constellation, wherein the unitary rotation is selected to optimize a distance function of the multidimensional mother constellation, and applying a set of operations to the multidimensional mother constellation to produce a set of constellation points. The method also includes storing the set of constellation points as the codebook of the plurality of codebooks.