The present disclosure provides a method of measuring a small cell based on a discovery signal. The method may include the step of receiving a discovery signal measurement timing configuration (DMTC) for a neighboring small cell. In this step, the DMTC may include DMTC periodicity information and information on a discovery signal occasion section. The information on the discovery signal occasion section may indicate one or more sub-frames in which the discovery signal occurs. The method may include the step of measuring the neighboring small cell for a measurement gap in the case where the neighboring small cell operates at a frequency that is different from a serving cell.

Disclosed is a random access method for a machine type communication (MTC) terminal. The random access method performed by a terminal includes performing a cell search, determining a radio environment based on time taken to perform the cell search, and performing different random access procedures depending on the determined radio environment. Accordingly, coverage of the MTC terminal that is in a poor radio environment may be enhanced, thereby performing normal communication with a base station.

An embodiment of the present invention relates to a method for transmitting a synchronization signal in a wireless communication system, the method comprising the steps of: generating a synchronization signal on the basis of a cell ID which is determined depending on whether a terminal for transmitting the synchronization signal is a terminal located outside of a coverage; and transmitting the synchronization signal.

The present invention provides a signal sending apparatus, a signal detection apparatus, a signal sending and detection system, a signal sending method, and a signal detection method. The apparatus determines a time unit that is in each time window and that is used to transmit a synchronization signal, and transmits the synchronization signal in the determined time unit in each time window. Therefore, a synchronization signal is always located in a time unit that has a fixed location in each time window, so that a device at a receive end needs to perform detection only in a fixed time unit in each time window, thereby reducing complexity of designing and detecting the synchronization signal.

A method and apparatus provides a determination of a set of sequence values to be used as synchronization signal sequences, the set of sequence values having a predetermined length. Each sequence value in the set is based upon a first maximum length sequence having a first cyclic shift, and is based upon a second maximum length sequence having a second cyclic shift. For at least one group of possible sequence values from the determined set, where a value of a cyclic shift difference between the second cyclic shift of the second maximum length sequence and the first cyclic shift of the first maximum length sequence upon which each of the possible sequence values in the group are based are equal, a cyclic shift difference between the respective first cyclic shift value of the first maximum length upon which each of the possible sequence values in the group are based for any two of the possible sequence values in the group are larger than or equal to a threshold value, where the threshold value is determined based on an expected maximum carrier frequency offset value. The method further includes assigning each one of the determined set of sequence values to respective at least one communication target of a plurality of communication targets.

Certain aspects of the present disclosure relate to methods and apparatus for generating synchronization signals for cell synchronization. Certain aspects of the present disclosure provide a method for wireless communication. The method generally includes determining a symbol index for transmitting a sequence; determining an amount of cyclical shift in one of a frequency domain and a time domain to apply to the sequence, wherein the amount of cyclical shift in the frequency domain is based on the sequence and the symbol index; shifting the sequence by the amount of cyclical shift; and transmitting the shifted sequence in a symbol corresponding to the symbol index.

Embodiments of an access point (AP), station (STA) and method for multi-user (MU) location measurement are generally described herein. The AP may contend for a transmission opportunity (TXOP) to obtain access to a channel. The AP may transmit a trigger frame (TF) to initiate a multi-user (MU) location measurement during the TXOP. The AP may receive service requests for the MU location measurement from a plurality of STAs. The AP may transmit an MU acknowledgement (ACK) frame that indicates reception of the service requests. The AP may receive, from the STAs, uplink sounding frames that include per-STA timing information for the service requests and the MU ACK frame. The STA may determine location measurements for the STAs based on the per-STA timing information included in the uplink sounding frames.

One disclosure of the present specification provides a method for performing measurement based on discovery signals. The method may comprise the steps of: receiving, from cells, discovery signals based on cell-specific reference signals (CRSs); and performing measurement based on the CRS-based discovery signals for a predetermined measurement period. If a measurement bandwidth is six resource blocks (RBs), the predetermined measurement period can be determined by 5*the measurement occasion periodicity of the discovery signals. If the measurement bandwidth is 25 resource blocks (RBs), the predetermined measurement period can be determined by 3*the measurement occasion periodicity of the discovery signals. Also, the discovery signals can be received for a discovery signal occasion duration defined by N consecutive subframes.

A transmission control method is disclosed. The transmission control method includes: sending, by a base station, downlink data to a terminal at a high frequency when detecting that the downlink data needs to be transmitted at the high frequency; and sending, by the terminal to the base station at the high frequency, control information used for assisting the base station in improving transmission quality of the high frequency downlink data, so that the base station controls a transmission process of the high frequency downlink data according to the control information. Embodiments of the present invention further disclose a base station and a terminal. By means of the present invention, a terminal can rapidly feed back control information at a high frequency in a process in which downlink data is transmitted at a high frequency, and a feedback time is short.

In one aspect of the teachings herein, a radio network node advantageously adapts the transmission duration of a synchronization signal with respect to transmission of the synchronization signal in different directions. For example, the radio network node uses a shorter transmission duration in beam directions that are associated with better reception conditions and a longer transmission duration in beam directions that are associated with poorer reception conditions. As a consequence of varying the transmission duration according to received-signal qualities known or expected for the different directions, the radio network node can shorten the overall time needed to complete one synchronization-signal transmission cycle and use less energy, as compared to using a more conservative, longer transmission time in all beam directions.