Patent ID: 9680586
Date: 2017-06-13
CPC Classifications: G09G,H04J,H04L

Claim:
1. A method of controlling a time division duplexing (TDD) Transmit/Receive (Tx/Rx) switching timing in a cloud radio access network (CRAN) in which at least one radio unit (RU) including a first RU frame timer for generating a first type of frame at the RU and a second RU frame timer for generating a second type of frame at the RU is connected with a digital unit (DU) having a first DU frame timer for generating the first type of frame at the DU and a second DU frame timer for generating the second type of frame at the DU, the method comprising: determining, by the at least one RU, a boundary of a wireless frame signal transmitted from the DU to synchronize the first RU frame timer with the first DU frame timer, the DU being connected with the RU; receiving, by the DU, from the at least one RU, a report comprising a frame offset, wherein the frame offset is received from the at least one RU through an upper layer message; calculating, in advance by the DU, link delay information for the at least one RU based on their respective frame offset, wherein the link delay information is calculated based on T (i) T (ii) T (iii) T (iv) T transmitting, by the DU, the link delay information to at least one RU; updating, by the at least one RU, the first RU frame timer based on the link delay information received from the DU; transmitting, by the at least one RU, a first acknowledgement message in response to the updating of the first RU frame timer; updating, by the at least one RU, frame timing information for the second type of frame based on information about a difference between a timing for the first type of frame and a frame timing for the second type of frame, delivered from the DU transmitting, by the at least one RU, a second acknowledgement message in response to the updating of the frame timing information for the second type of frame; and controlling a TDD Tx/Rx switching timing by replacing Tx/Rx switching timing information for each antenna carrier (AxC) delivered from the DU to the first RU frame timer and the second RU frame timer; wherein the first type of frame is a Common Public Radio Interface (CPRI) frame, and wherein the second type of frame is an Evolved Universal Terrestrial Radio Access (E-UTRA) frame.