A method of changing a user equipment mobility state based on background traffic, the method comprises the steps of: a user equipment establishing a first RRC link with a cell when operating in a first mobility state of an RRC connected mode, wherein the cell is an evolved universal terrestrial radio access network base station in a 4 th Generation long term evolution system; the user equipment sending a first message to the cell when the user equipment remains operating in a background mode longer than a predetermined period of time after having established the first RRC link; and the user equipment switching from the first mobility state to a second mobility state of the RRC connected mode when the user equipment is able to receive a second message from the cell before a first timer expires, wherein: the first message is associated with changing the user equipment mobility state; the second message is associated with approving a change of the user equipment mobility state and includes a radio resource configuration associated with the second mobility state; a first monitor frequency of the user equipment when operating in the first mobility state is higher than a second monitor frequency of the user equipment when operating in the second mobility state; and all application programs run on the user equipment are non-user interactive when the user equipment operates in the background mode. a user equipment establishing a first RRC link with a cell when operating in a first mobility state of an RRC connected mode, wherein the cell is an evolved universal terrestrial radio access network base station in a 4 th Generation long term evolution system; the user equipment sending a first message to the cell when the user equipment remains operating in a background mode longer than a predetermined period of time after having established the first RRC link; and the user equipment switching from the first mobility state to a second mobility state of the RRC connected mode when the user equipment is able to receive a second message from the cell before a first timer expires, wherein: the first message is associated with changing the user equipment mobility state; the second message is associated with approving a change of the user equipment mobility state and includes a radio resource configuration associated with the second mobility state; a first monitor frequency of the user equipment when operating in the first mobility state is higher than a second monitor frequency of the user equipment when operating in the second mobility state; and all application programs run on the user equipment are non-user interactive when the user equipment operates in the background mode. the first message is associated with changing the user equipment mobility state; the second message is associated with approving a change of the user equipment mobility state and includes a radio resource configuration associated with the second mobility state; a first monitor frequency of the user equipment when operating in the first mobility state is higher than a second monitor frequency of the user equipment when operating in the second mobility state; and all application programs run on the user equipment are non-user interactive when the user equipment operates in the background mode.