Universal Mobile Telecommunication System (UMTS) is migrating from a Code Division Multiple Access (CDMA) based air interface to an Orthogonal Frequency Division Multiple Access (OFDMA) based air interface in order to increase reverse link capacity. Reverse link capacity can be increased by limiting interference caused by mobile stations within a same cell (also referred to herein as “in-cell interference”) or by mobile stations in other cells (also referred to herein as “other-cell interference”).
In-cell and outer-cell Interference are caused, in part, when mobile stations transmit over a same carrier or sub-carrier frequency simultaneously. In a CDMA system, i.e., wireless communication system utilizing a CDMA air interface, mobile stations produces both in-cell interference and other-cell interference because mobile stations in the same cell and in different cells are simultaneously transmitting on a same carrier frequency. In-cell interference is the main source of interference in a CDMA system. By contrast, the main source of interference in an OFDMA system, i.e., wireless communication system utilizing an OFDMA air interface, is other-cell interference. In an OFDMA system, mobile stations in the same cell transmit on different sub-carrier frequencies and, thus, the in-cell interference produced by the mobile stations should be insignificant. However, other-cell interference is still produced because mobile stations in different cells may be simultaneously transmitting on the same sub-carrier frequencies. Accordingly, OFDMA systems have higher reverse link capacity than CDMA systems because mobile stations in an OFDMA system produce less in-cell interference than mobile stations in a CDMA system.
In order to increase reverse link capacity in an OFDMA system, other-cell interference needs to be reduced. One way to reduce other-cell interference is to limit mobile stations near the edges of adjacent cells to different sets of sub-carrier frequencies. For example, mobile stations near the edge of a first cell would be restricted to using a first set of sub-carrier frequencies, and mobile stations near the edge of an adjacent second cell would be restricted to using a second set of sub-carrier frequencies, wherein the first set includes different sub-carrier frequencies than those in the second set. Edge mobile stations (i.e., mobile stations near the edge of a cell) in the second cell would not be able to use the first set of sub-carrier frequencies even when there are no edge mobile stations in the first cell using sub-carrier frequencies in the first set, or vice-versa. Such manner of reducing other-cell interference will, however, result in an inefficient use of reverse link resources. Accordingly, there exists a need for a method of managing other-cell interference in a wireless communication system more efficiently.