1. Field of the Invention
The present invention relates to a wireless communication system.
2. Description of the Related Art
In a 4th Generation (4G) communication system that is the next generation communication system, intensive research is being conducted to provide users with high-speed services having various Qualities of Service (QoS). 4 G communication systems include an Institute of Electrical and Electronics Engineers (IEEE) 802.16e system, a 3rd Generation Partnership Project (3GPP)/3GPP2 Long Term Evolution (LTE) system, and the like. In particular, research on the 4 G communication system is being actively made to support high-speed services in the way of guaranteeing mobility and QoS for a broadband wireless access communication system such as a Wireless Local Area Network (WLAN) system and a Wireless Metropolitan Area Network (WMAN) system.
As one means for providing a broadband service, a study on increasing spectral efficiency is being carried out. In general, spectral efficiency is maximized when a frequency reuse rate is equal to ‘1’. However, when the frequency reuse rate is equal to ‘1’, significant interference is caused between cells, because the same frequency channel is reused in all Base Stations (BSs). In this case, although each BS increases transmission power, capacity does not increase, because inter-cell interference similarly increases. To increase the spectral efficiency in this environment, it is important to effectively control the inter-cell interference.
In order to effectively control the inter-cell interference using frequency resource distribution between neighboring BSs, a Fractional Frequency Reuse (FFR) technique has been proposed. According to the FFR technique, a part of a frequency resource is redundantly used in all sectors, and is mostly allocated to users who are located in a cell center area not subject to a large amount of inter-cell interference. The remaining portions of the frequency resource is a region divided and used without redundancy between neighboring sectors, and is mostly allocated to users who are located in a cell boundary area having significant inter-cell interference. The disadvantages associated with the FFR technique are that an available frequency resource is reduced due to non-use of part of the whole frequency resource, and that an average sector capacity is decreased.
Upon installation, the FFR technique must determine a frequency allocation pattern between neighboring sectors. For example, upon network installation, the FFR technique should determine a frequency pattern for FFR and a frequency limitation resource and limitation power level suitably to a cell environment. After the network installation, if the cell environment is changed, the FFR technique requires the cumbersome work associated with manually changing the FFR frequency pattern through re-execution of cell planning. In addition, even if the cell environment is not changed, if users are instantaneously concentrated in the cell boundary area or cell center area, the FFR technique requires that the FFR frequency pattern be instantaneously changed to take the configuration or concentration of the users into account. For example, if the users are concentrated in the cell center area, it is desirable to use, without division, all resources and power, because all users within a cell experience less interference. For another example, if all users are located in the cell boundary area, it is desirable to divide and use all regions between neighboring sectors, because all the users within the cell experience significant interference influence. However, the FFR technique is impossible to change the frequency pattern or control the power adaptively to the instantaneous distribution of the users, because using a previously planned and set frequency pattern.
As described above, a disadvantage associated with the FFR technique is that the FFR technique fails to reflect an instantaneous communication environment. Accordingly, there is a need to propose an alternative for controlling interference more effectively according to an instantaneous resource use status.
Therefore, a need exists for an apparatus, system and method for mitigating inter-cell interference in a wireless communication system.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention.
USPTO Backgrounds
USPTO Backgrounds