Abstract: [Problem] When the number of data radio bearers increases, the number of DL user data messages increases, and as a result, many communication bands in a transmission path are consumed. [Solution] A first message for requesting a report of a data transmission status in a plurality of data radio bearers among first bearers representing data radio bearers established in relation to a second communication device is generated, and the first message is transmitted to the second communication device.

Abstract: To enable a communication band between base stations to be efficiently used, a wireless communication system provided with a main base station and a secondary base station. A wireless communication system, wherein when dual connectivity, which is an operation mode that allows connection to both the main base station and the secondary base station by a terminal, is executed, the secondary base station transmits information pertaining to the free buffer space of a wireless data bearer group comprising a plurality of wireless data bearers to the main base station in units of a wireless data bearer group.

Abstract: To enable a communication band between base stations to be efficiently used, a wireless communication system provided with a main base station and a secondary base station. A wireless communication system, wherein when dual connectivity, which is an operation mode that allows connection to both the main base station and the secondary base station by a terminal, is executed, the secondary base station transmits information pertaining to the free buffer space of a wireless data bearer group comprising a plurality of wireless data bearers to the main base station in units of a wireless data bearer group.

Abstract: Provided is a communication system for preventing the wasteful consumption of a wireless band and a reduction in the immediacy of a response. A first wireless communication device in the communication system having the first wireless communication device and a second wireless communication device, wherein the first wireless communication device has a first restorer for restoring a packet and a first compressor for compressing a packet, and the second wireless communication device has a second restorer for restoring a packet and a second compressor for compressing a packet. A session group corresponding to a plurality of sessions is set between the first compressor and the second restorer, and the first compressor transmits to the second restorer a message that pertains to the restoration condition of the packet and that corresponds to the session group.