In the multiple short sequence based SRS, multiple items of sequence data having a short sequence length corresponding to a partial band are used for transmitting SRS in discontinuous bands. In the multiple short sequence based SRS, a terminal specifies a frequency domain to be used for transmitting a reference signal using predetermined sequence data, applies a phase shift index associated with the specified frequency domain to the reference signal, and transmits the reference signal to which the phase shift index is applied by using the specified frequency domain.

A radio performs random access by receiving control information and grouping a predetermined number of sequences that are generated from a plurality of base sequences into a plurality of groups by partitioning the predetermined number of sequences. At least one of the groups is associated with a first respective range of data amounts and a first respective range of reception qualities. Sequences generated from a common base sequence are arranged in an increasing order of respective cyclic shifts associated with the sequences. A sequence is randomly selected from a plurality of sequences contained in one group of the plurality of groups. A position at which the predetermined number of sequences are partitioned is determined based on the control information. A number of sequences contained in each of the plurality of groups varies in accordance with the control information.

In the multiple short sequence based SRS, multiple items of sequence data having a short sequence length corresponding to a partial band are used for transmitting SRS in discontinuous bands. In the multiple short sequence based SRS, a terminal specifies a frequency domain to be used for transmitting a reference signal using predetermined sequence data, applies a phase shift index associated with the specified frequency domain to the reference signal, and transmits the reference signal to which the phase shift index is applied by using the specified frequency domain.

In the multiple short sequence based SRS, multiple items of sequence data having a short sequence length corresponding to a partial band are used for transmitting SRS in discontinuous bands. In the multiple short sequence based SRS, a terminal specifies a frequency domain to be used for transmitting a reference signal using predetermined sequence data, applies a phase shift index associated with the specified frequency domain to the reference signal, and transmits the reference signal to which the phase shift index is applied by using the specified frequency domain.

In the multiple short sequence based SRS, multiple items of sequence data having a short sequence length corresponding to a partial band are used for transmitting SRS in discontinuous bands. In the multiple short sequence based SRS, a terminal specifies a frequency domain to be used for transmitting a reference signal using predetermined sequence data, applies a phase shift index associated with the specified frequency domain to the reference signal, and transmits the reference signal to which the phase shift index is applied by using the specified frequency domain.

A user terminal apparatus includes a receiver to receive a control information value belonging to a set of multiple control information values. Each control information value in the set of multiple control information values is associated with a subset of random access sequences from multiple subsets of random access sequences. Different ones of the multiple subsets of random access sequences are associated with different amounts of data. A data processor selects a random access sequence from one of the subset of random access sequences based on the control information value. A transmitter transmits the selected random access sequence.

In the multiple short sequence based SRS, multiple items of sequence data having a short sequence length corresponding to a partial band are used for transmitting SRS in discontinuous bands. In the multiple short sequence based SRS, a terminal specifies a frequency domain to be used for transmitting a reference signal using predetermined sequence data, applies a phase shift index associated with the specified frequency domain to the reference signal, and transmits the reference signal to which the phase shift index is applied by using the specified frequency domain.

In the multiple short sequence based SRS, multiple items of sequence data having a short sequence length corresponding to a partial band are used for transmitting SRS in discontinuous bands. In the multiple short sequence based SRS, a terminal specifies a frequency domain to be used for transmitting a reference signal using predetermined sequence data, applies a phase shift index associated with the specified frequency domain to the reference signal, and transmits the reference signal to which the phase shift index is applied by using the specified frequency domain.

Methods, systems, and devices for wireless communications are described. A wireless device such as a user equipment (UE) may identify a codebook matrix having a number of rows equal to a first number and a number of columns equal to a second number, the first number equal to a number of UEs supported for communication with a base station, and the second number equal to a sequence length of a set of UE specific signature sequences, where the rows of the codebook matrix comprise a Welch bound equality (WBE) achieving vector set. The UE may identify a UE specific signature sequence based at least in part on a mapping between an identifier associated with the UE to one or more rows of the codebook matrix, and communicate with the base station based at least in part on the UE specific signature sequence.

A radio performs random access by receiving control information and grouping a predetermined number of sequences that are generated from a plurality of base sequences into a plurality of groups by partitioning the predetermined number of sequences. At least one of the groups is associated with a first respective range of data amounts and a first respective range of reception qualities. Sequences generated from a common base sequence are arranged in an increasing order of respective cyclic shifts associated with the sequences. A sequence is randomly selected from a plurality of sequences contained in one group of the plurality of groups. A position at which the predetermined number of sequences are partitioned is determined based on the control information. A number of sequences contained in each of the plurality of groups varies in accordance with the control information.