Certain aspects of the present disclosure relate to methods and apparatus for pilot design for Narrow-Band Internet of Things (NB-IoT). In certain aspects, the method generally includes determining at least one binary code sequence to use as a demodulation reference signal (DMRS) for a channel transmitted across one or more subframes using one or more tones within a resource block (RB) allocated to the UE for narrowband communication, and transmitting the channel including the DMRS using the one or more tones and the determined binary code sequence. In certain aspects, the binary code sequence may be determined based on a binary random sequence, such as pseudo noise (PN) or Gold sequence.

Provided is a transmitting device which can expand a communication range when performing multicast/broadcast communication. The transmitting device includes a plurality of transmission antennas, and includes: a signal processor which generates a first baseband signal by modulating data of a first stream, and a second baseband signal by modulating data of a second stream; and a transmitter which generates, from the first baseband signal, first transmission signals having different directivities, generates, from the second baseband signal, second transmission signals having different directivities, and transmits the first transmission signals and the second transmission signals at a same time. When the transmitter has received, from a terminal, a request to transmit the first stream, the transmitter further generates, from the first baseband signal, third transmission signals which are different from the first transmission signals and have different directivities, and transmits the third transmission signals.

A user equipment (UE) may spatial time-division multiplex a plurality of sounding reference signal (SRS) ports, each of the plurality of SRS ports being associated with at least one of a set of orthogonal weights, the set of orthogonal weights corresponding to phase shifting, and transmit a plurality of SRSs via the plurality of spatially time-division multiplexed SRS ports simultaneously, each of the plurality of SRSs including at least two SRS repetition. The plurality of SRSs may be configured to form or present a quasi-co-location (QCL) receive (Rx) beam subspace. The UE may configure the plurality of SRSs to form the subspace as the QCL Rx beam subspace, and a base station may signal the UE to a specific Rx beam subspace such that it is aligned to the base station's beamforming direction, and achieve spatial multiplexing gain in the QCL Rx beam subspace.

Methods and apparatuses are provided for wireless communication. Control symbols are mapped to a plurality of resource element groups (REGs) which is not assigned to a physical channel format indication channel (PCFICH) or a physical hybrid automatic repeat request indicator channel (PHICH). The REGs are allocated based on a time first manner. The mapped control symbols are transmitted on a packet dedicated control channel (PDCCH).

Sparse reference signal-related signaling, for a wireless channel that is associated with multiple antenna ports, is communicated with a User Equipment (UE). The sparse reference signal-related signaling is consistent with a sparse signaling pattern. In an embodiment, the sparse signaling pattern includes reference signal-related signaling associated with each of the antenna ports, and has been determined based on previous reference signal-related signaling previously communicated with the UE or another UE. In another embodiment, the sparse reference signal-related signaling is consistent with a varying sparse signaling pattern that is based on previous reference signal-related signaling previously communicated with the UE or another UE.

A base station includes a transceiver, and a processor configured to allocate at least one CSI-RS antenna port to a user equipment (UE), precode the at least one CSI-RS antenna port with a first precoding matrix, cause the transceiver to transmit the at least one CSI-RS antenna port precoded with the first precoding matrix through a channel to the UE, cause the transceiver to signal a number of the at least one antenna port to the UE, cause the transceiver to receive an index for a second precoding matrix from the UE, wherein the second precoding matrix is determined by the UE according to the at least one CSI-RS antenna port precoded with the first precoding matrix as received through the channel by the UE and the signaled number of the at least one antenna port, and precode transmission data with the first precoding matrix and the second precoding matrix.

A method and apparatus are provided for reducing the number of pilot symbols within a MIMO-OFDM communication system, and for improving channel estimation within such a system. For each transmitting antenna in an OFDM transmitter, pilot symbols are encoded so as to be unique to the transmitting antenna. The encoded pilot symbols are then inserted into an OFDM frame to form a diamond lattice, the diamond lattices for the different transmitting antennae using the same frequencies but being offset from each other by a single symbol in the time domain. At the OFDM receiver, a channel response is estimated for a symbol central to each diamond of the diamond lattice using a two-dimensional interpolation. The estimated channel responses are smoothed in the frequency domain. The channel responses of remaining symbols are then estimated by interpolation in the frequency domain.

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.

A single input single output (SISO) data transmission may solicit a multiple input multiple output (MIMO) rank adaptation information. A number of transmit chain for transmission may be determined, e.g., by an access point (AP). A physical layer convergence procedure (PLCP) protocol data unit (PPDU) may be transmitted, e.g., to a station (STA). The PPDU may include data and training (TRN) sequences. The number of TRN sequences may be equal to the number of transmit chains. The PPDU may include information associated with the determined number of transmit chains for transmission. Feedback may be received, e.g., from the STA. The feedback may include information that identifies a transmit chain associated with the transmitted TRN sequences and/or a channel measurement associated with the identified transmit chain. A subsequent PPDU may be transmitted based on the channel measurement associated with the identified transmit chain from the received feedback.

Pilot, preamble and midamble patterns are provided that are particularly suited for four transmit antenna OFDM systems. Pilots are inserted in a scattered manner for each of the four antennas, either uncoded, space-time coded in pairs, space-time frequency coded in pairs, or space-time-frequency coded.