TECHNICAL FIELD

The present disclosure relates to a user terminal and a radio communication method in next-generation mobile communication systems.

BACKGROUND ART

In the UMTS (Universal Mobile Telecommunications System) network, the specifications of long term evolution (LTE) have been drafted for the purpose of further increasing high speed data rates, providing lower latency and so on (see non-patent literature 1). Also, the specifications of LTE-A (also referred to as “LTE-advanced,” “LTE Rel. 10,” “LTE Rel. 11,” “LTE Rel. 12” or “LTE Rel. 13”) have been drafted for further broadbandization and increased speed beyond LIE (also referred to as “LTE Rel. 8” or “LTE Rel. 9”), and successor systems of LTE (also referred to as, for example, “FRA (Future Radio Access),” “5G (5th generation mobile communication system),” “NR (New Radio),” “NX (New radio access),” “FX (Future generation radio access),” “LTE Rel. 14,” “LTE Rel. 15” or later versions) are under study.

In LTE Rel. 10/11, carrier aggregation (CA) to integrate multiple component carriers (CC) is introduced in order to achieve broadbandization. Each CC is configured with the system bandwidth of LTE Rel. 8 as one unit. In addition, in CA, multiple CCs under the same radio base station (eNB (eNodeB)) are configured in a user terminal (UE (User Equipment)).

Meanwhile, in LTE Rel. 12, dual connectivity (DC), in which multiple cell groups (CGs) formed with different radio base stations are configured in a UE, is also introduced. Each cell group is comprised of at least one cell (or CC). In DC, since multiple CCs of different radio base stations are integrated, DC is also referred to as “inter-eNB CA.”

Also, in existing LTE systems (for example, LTE Rels. 8 to 13), synchronization signals (PSS/SSS), broadcast channels (PBCHs) and so on which a user terminal uses in initial access procedures are allocated, on a fixed basis, in domains that are determined in advance. By detecting the synchronization signals in cell search, the user terminal can establish synchronization with the network, and, furthermore, identify the cell (for example, cell ID) which the user terminal should connect with. Furthermore, the user terminal can acquire system information by receiving broadcast channels (PBCHs and SIBs) after the cell search.

CITATION LIST

Non-Patent Literature

Non-Patent Literature 1: 3GPP TS36.300 V8.12.0 “Evolved Universal Terrestrial Radio Access (E-UTRA) and Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Overall description; Stage 2 (Release 8),” April, 2010

SUMMARY OF INVENTION

Technical Problem

Future radio communication systems (for example, 5G, NR, etc.) are expected to realize various radio communication services so as to fulfill mutually varying requirements (for example, ultra high speed, large capacity, ultra-low latency, etc.). For example, regarding 5G/NR, studies are in progress to provide radio communication services, referred to as “eMBB (enhanced Mobile Broad Band),” “IoT (Internet of Things),” “mMTC (massive Machine Type Communication),” “M2M (Machine To Machine),” and “URLLC (Ultra Reliable and Low Latency Communications).”

In addition, 5G/NR is expected to support flexible use of numerologies and frequencies, and realize dynamic frame configurations. Here, “numerology” refers to communication parameters in the frequency direction and/or the time direction (for example, at least one of the subcarrier spacing (subcarrier interval), the bandwidth, the symbol duration, the time duration of CPs (CP duration), the subframe duration, the time duration of TTIs (TTI duration), the number of symbols per TTI, the radio frame configuration, the filtering process, the windowing process, and so on).

However, how to control transmission/receipt of signals when different numerologies (subcarrier spacing, bandwidth etc.) from those of existing LTE systems are supported is a problem. In 5G/NR, a study is in progress to provide services using a very high carrier frequency of 100 GHz, and on the assumption that DL transmission is performed using different methods from those of existing LTE systems.

For example, DL signals such as synchronization signals for use for initial access and/or other events and broadcast channels are anticipated to be transmitted based on different configurations (for example, different mapping methods) from those of existing LTE systems. In this case, it is desirable to use signal configurations that can reduce the load and/or the latency when a UE gains initial access.

It is therefore an object of the present disclosure to provide a user terminal and a radio communication method that can reduce the load and/or the latency of UEs in radio communication systems in which communication is performed using configuration different from those used in existing LTE systems.

Solution to Problem

In accordance with one aspect of the present disclosure, a user terminal has a receiving section configured to receive a first synchronization signal (PSS), a second synchronization signal (SSS), and a broadcast channel (PBCH), and a control section configured to control, in a predetermined block that is formed by a predetermined number of symbols and a predetermined number of subcarriers, reception of the PSS and the SSS which are located in a first frequency domain, and the PBCH which is located in at least part of a second frequency domain that is broader than the first frequency domain, wherein the PBCH is located in the predetermined block in at least part of a predetermined domain that is neighbor with the SSS in the frequency direction, and the PBCH is not located in a predetermined domain that is neighbor with the PSS in the frequency direction.

Advantageous Effects of Invention

According to one aspect of the present disclosure, the load and/or the latency of UEs can be reduced in radio communication systems, in which communication is performed using configuration different from those used in existing LTE systems.

