Mobile Communication System, Base Station Device and Frequency Allocation Method for Mobile Communication System

Abstract

In a base station device 12 of an OFDMA mobile communication system, a frequency band storage unit 22 stores multiple frequency bands allocatable to mobile station devices, respectively, in association with predetermined conditions related to communication quality. A communication quality acquisition unit 37 acquires communication quality in communication with each of the mobile station devices. A frequency allocator 24 selects any one of the frequency bands from the frequency band storage unit 22 on the basis of the communication quality acquired by the communication quality acquisition unit 37, and notifies the mobile station device of channel information indicating the selected frequency band. Then, the mobile station device communicates with the base station device 12 in the frequency band indicated by the channel information notified by the frequency allocator 24 in the base station device 12.

Description

TECHNICAL FIELD[0001]The present invention relates to a mobile communication system, a base station device and a frequency allocation method for the mobile communication system. In particular, the present invention relates to a mobile communication system for performing communication by orthogonal frequency division multiplexing, a base station device and a frequency allocation method for the mobile communication system.BACKGROUND ART[0002]OFDM (Orthogonal Frequency Division Multiplexing) is one type of multicarrier modulation method and is a method for performing communication by transmitting divided data on multiple subcarriers which are orthogonal to each other. Each of the subcarriers is modulated by QPSK (Quadrature Phase Shift Keying), QAM (Quadrature Amplitude Modulation) or the like. When the subcarriers are orthogonal to each other, each of the subcarriers has a frequency in which the power of the other subcarriers is set to zero as shown in FIG. 1. Thus, the subcarriers ca...

AI Technical Summary

Benefits of technology

[0010]The present invention has been made in view of the conventional problems described above. It is an object of the present invention to provide a mobile communication system, a base station device and a frequency allocation method for the mobile communication system, which enable appropriate frequency allocation while improving both frequency utilization efficiency and throughput in OFDMA radio communication.

[0014]According to the present invention, in the base station device, the multiple allocatable frequency bands are stored in association with the predetermined conditions related to the communication quality. Then, based on communication quality in communication with each of the mobile station devices, a frequency band to be allocated to the mobile station device is selected. Moreover, channel information indicating the selected frequency band is notified to the mobile station device. Then, the mobile station device notified of the channel information by the base station device communicates with the base station device in the frequency band indicated by the channel information. According to the present invention, in OFDMA radio communication, multiple allocatable frequency bands can be appropriately associated with the conditions related to the communication quality. Thus, on the basis of the communication quality in communication with each of the mobile station devices, appropriate frequency allocation can be performed while improving both frequency utilization efficiency and throughput.

[0015]Moreover, according to one aspect of the present invention, a guard band having a predetermined width according to the communication quality is provided between the frequency bands stored in the frequency band storage unit. Thus, the number and bandwidth of the guard bands provided between the frequency bands can be reduced. Consequently, the frequency utilization efficiency can be improved. Moreover, the frequencies in a portion where no guard bands are provided between the frequency bands can be allocated to the mobile station device which performs high quality communication since ICI is unlikely to occur. Meanwhile, the frequencies in a portion where the guard bands having a proper bandwidth according to the quality are provided can be allocated to the mobile station device which performs low quality communication since ICI is likely to occur. Thus, the throughput can be improved while suppressing a data error rate.

Problems solved by technology

Thus, communication quality is deteriorated.

Accordingly, although the communication throughput is improved, there is a problem that the frequency utilization efficiency is lowered.

Meanwhile, when data retransmission or error correction is performed instead of providing the guard bands, the frequency utilization efficiency is improved but a problem of lowering the communication throughput arises.

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