1. Field of the Invention
The present invention relates to mobile gateways disposed between a plurality of base stations connecting a plurality of mobile terminals and a service network, a control method for the gateways and radio access network equipped with the gateways.
2. Background of the Invention
Today, in the field of mobiles communication networks, high-speed (known as 3.9G) mobile broadband lines including Worldwide Interoperability for Microwave Access (WiMAX) and Long Term Evolution (LTE) are in extensive use as further developed versions of 3.5G network services including 3G high-speed data communication services such as HSPA and EV-DO. Furthermore, expansion of the radio frequency bandwidth by carrier aggregation is scheduled for a service known as LTE-Advanced, which would make possible another step ahead in communication speed. In the 3.9G sector, connection of high-performance mobile terminals called Smartphone and personal computers to the Internet via one or another of these mobile broadband lines is becoming a common practice, and the communication speed is more than 100 Mbps in some radio frequency bandwidths.
Along with the expanded use of mobile broadband services, it is also required to raise the access line speed of connections to base stations of the mobile communication network and the network line speed between mobile gateways connected to base stations to accommodate mobile terminals and the base stations.
Meanwhile, along with the increase in mobile broadband speed, the difference in traffic volume between the connected state and the idle state is expanding. At the same time, the number of mobile terminals covered by each base station significantly varies with the time and the installed position. For instance, a base station located in a downtown area handles heavy traffic in the daytime while having scarce traffic from late at night until early in the morning. Conversely, a base station close to a residential area has a heavy traffic load from the evening until late at night. For a mobile broadband system such as WiMAX or LTE, the bandwidth necessary for the communication route to the base station greatly varies with the relationship between the communication capacity of the base station and those of mobile terminals.
For instance, where mobile terminals of 75 Mbps in communication capacity are connected to a base station of 150 Mbps in communication capacity, the bandwidth necessary for communication to the mobile terminals is 75 Mbps. Or where base stations constitute a plurality of sectors, the bandwidth necessary for communication routes to the base stations also varies significantly with the arrangement of the mobile terminals to the sectors. For base stations each of whose sectors has a communication capacity of 75 Mbps, where two mobile terminals having a communication capacity of 75 Mbps exist only in one sector, the bandwidth necessary for communication routes to the base stations is at most 75 Mbps but two such mobile terminals exist in different sectors, then the bandwidth necessary for communication routes to the base stations is 150 Mbps at the maximum.
Regarding bandwidth allocation to base stations, for instance Japanese Patent Laid-Open Publication No. 2012-222380 describes bandwidth allocation to mobile terminals according to the service level of each mobile terminal along with bandwidth allocation to base stations according to the load on each base station.