Small cell is introduced in release 12 of Long Term Evolution (LTE). A small cell is a radio access node which has a low power, operates on licensed or unlicensed frequency spectrums, and may cover a range of 10 m to 200 m. An LTE network deployed in a licensed frequency band may be deployed widely all over the world. In order to further increase a capacity of the LTE network so as to meet a highly increasing requirement of data, a radio interface and a transmission mechanism of the LTE may be adjusted such that data can be transmitted by using the unlicensed frequency spectrum resource. The technology is referred to as Licensed Assisted Access (LAA)-LTE.
From the perspective of a user, the user may obtain a better quality of service by efficiently using the unlicensed frequency spectrum resource. Improvement of user experience and transparent transmission for the unlicensed frequency band may provide more flexibility for an operator and may also enable the operator to obtain higher gains by developing and using the unlicensed frequency band. Accordingly, this will promote the operator to develop the unlicensed frequency spectrum more.
In order to use an unlicensed frequency band of, e.g., 5 GHz as a target frequency band, some additional standards need to be established to meet different requirements for different regions. In order to carry out a semi-static detection and reduce interference on a non-International Mobile Telecommunication (IMT) system such as a radar system, a dynamic frequency selection (DFS) mechanism is widely used in some regions. Listen Before Talk (LBT) provides a flexible and fair coexistence mechanism for different IMT and non-IMT systems. LBT can ensure rapid channel detection and dynamic channel occupation for the unlicensed frequency band. Although not being used widely, Transmission Power Control (TPC) technology is a method for limiting power leakage for an adjacent cell.
USPTO Backgrounds
USPTO Backgrounds