TECHNICAL FIELD

The present invention relates to a radio communication apparatus and method.

BACKGROUND ART

The spread of the internet of things (IoT) has increased demands for low-power and low-cost radio communication apparatuses. In order to satisfy such demands, there is an emerging radio communication scheme, low power wide area (LPWA) provided to achieve long-distance communication while suppressing power consumption. A radio communication apparatus that performs LPWA radio communication achieves power saving by stopping radio communication during a period that involves no data communication. Examples of known power saving technologies like these include power saving mode (PSM), extended discontinuous reception (eDRX) defined in the 3rd generation partnership project (3GPP) standards (for example, refer to Non Patent Literature 1).

Furthermore, when a radio communication apparatus is connected to a host device, the host device can communicate with a radio communication network via the radio communication apparatus even when the host device does not include a radio communication function. Since the time required for one communication event is generally short in a radio communication apparatus, it is conceivable to apply a user datagram protocol (UDP) which is a connectionless protocol in the transport layer.

CITATION LIST

Non Patent Literature

Non Patent Literature 1: 3GPP Technical Specifications “3GPP TS 23.401 V15.1.0” September 2017

SUMMARY

A radio communication apparatus according to a first feature is connected to a host device. The radio communication apparatus comprises a radio communicator configured to perform a radio communication with a radio communication network by an LPWA scheme, receive, from the radio communication network, data transmitted using a UDP, and transition to a power saving state in which the radio communication is stopped during a period occurring no data communication, and a transfer controller configured to transfer, to the host device, the data received by the radio communicator. A side of the radio communication network stores data addressed to the radio communication apparatus during a period in which the radio communicator is in the power saving state. The radio communicator is configured to receive the stored data when the radio communication resumes after the transitioning to the power saving state, and the transfer controller is configured to cause a buffer to hold the data received by the radio communicator when data transfer to the host device is impossible when the radio communicator resumes the radio communication.

A method according to a second feature is a method in a radio communication apparatus connected to a host device. The method comprises performing a radio communication with a radio communication network using an LPWA scheme, receiving, from the radio communication network, data transmitted using a UDP, transitioning to a power saving state in which the radio communication is stopped during a period occurring no data communication, storing data addressed to the radio communication apparatus on a side of the radio communication network during a period of the power saving state, receiving the stored data when resuming the radio communication, transferring the received data to the host device, and causing a buffer to hold data received from the radio communication network when data transfer to the host device is impossible.

A radio communication apparatus according to a third feature comprises a radio communicator configured to perform radio communication with a radio communication network according to an LPWA scheme and receive data from the radio communication network. The radio communicator is configured to resume the radio communication after a predetermined time elapses after transitioning to a power saving state in which the radio communication is stopped. The radio communicator is configured to transmit, to the radio communication network, a NAS message that stops or delays transmission of data to the radio communication apparatus, when resuming the radio communication or after resuming the radio communication.

A method according to a fourth feature is a method in a radio communication apparatus. The method comprises performing radio communication with a radio communication network according to an LPWA scheme, receiving data from the radio communication network, resuming the radio communication after a predetermined time elapses after transitioning to a power saving state in which the radio communication is stopped, and transmitting, to the radio communication network, a NAS message that stops or delays transmission of data to the radio communication apparatus, when resuming the radio communication or after resuming the radio communication.

