Method of controlling TDD Tx/Rx switching timing in cloud radio access network

• US 9,680,586 B2
• Filed: 05/22/2014
• Issued: 06/13/2017
• Est. Priority Date: 04/15/2014
• Status: Active Grant

• Current Assignee: Innowireless Co., Ltd.
• Original Assignee: Innowireless Co., Ltd.
• Inventors: Joung, Jin-Soup, Lee, Joo-Hyeong, Kim, Tae-Beom
• Primary Examiner(s): Mian, Omer S
• Application Number:
  US14/284,445
• Publication Number:
  US 20150295699A1
• Time in Patent Office: 1,118 Days
• CPC Class Codes: G09G 2370/14 Use of low voltage differential signaling [LVDS] for display data communication
• CPC Class Codes: H04J 3/047 Distributors with transistors or integrated circuits
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
• CPC Class Codes: H04L 27/26 Systems using multi-frequency codes H04L27/32 takes precedence
• CPC Class Codes: H04L 5/0078 Timing of allocation
• CPC Class Codes: H04L 5/1469 using time-sharing

Abstract

Provided is a method for controlling a time division duplexing (TDD) Tx/Rx switching timing in a cloud radio access network (CRAN) that can finely control a switching timing between transmission and reception of TDD signals with an additional component added to a digital unit (DU) and a radio unit (RU) in the CRAN.

Claims

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 T₁₂=T₃₄=(T₁₄−

T_offset)/2, and wherein;

(i) T₁₂ is a delay of a downlink signal from an output point (R1) of the DU to an input point (R2) of the at least one RU;

(ii) T₁₄ is a frame timing difference between the output point (R1) and an input point (R4) of the DU;

(iii) T_offset is the frame offset between the input point (R2) and an output point (R3) of the at least one RU; and

(iv) T₃₄ is a delay of an uplink signal from the output point (R3) of the at least one RU to the input point (R4) of the DU;

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.

2. The method of claim 1, wherein the determining of the boundary comprises checking the boundary of the wireless frame signal using a sync&

timing subchannel for each hyper frame of the wireless frame signal transmitted from the DU.

3. The method of claim 1, wherein each of the first RU frame timer and second RU frame timer is configured using a timer with an error of less than 10 ns.

4. The method of claim 2, wherein each of the first RU frame timer and second RU frame timer is configured using a timer with an error of less than 10 ns.