Radio communication terminal, radio base station and radio communication method

• US 10,075,981 B2
• Filed: 03/13/2015
• Issued: 09/11/2018
• Est. Priority Date: 03/28/2014
• Status: Expired due to Fees

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Yasukawa, Shimpei, Takeda, Kazuki, Nagata, Satoshi
• Primary Examiner(s): Krueger, Kent
• Application Number:
  US15/129,435
• Publication Number:
  US 20170118776A1
• Time in Patent Office: 1,278 Days
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access
• CPC Class Codes: H04W 74/0866 using a dedicated channel for access

Abstract

The present invention is designed to realize RACH traffic off-loading. A radio communication terminal communicates with a radio base station by using a carrier that is different from the connecting carrier and includes an unlicensed band, and has a transmission section that transmits a cross-carrier RACH in the carrier including the unlicensed band, and a receiving section that receive a random access response that is transmitted from the radio base station having received the cross-carrier RACH.

Claims

1. A radio communication terminal that communicates with a radio base station by using a carrier that is different from a connecting carrier and includes an unlicensed band, the radio communication terminal comprising:

a transmitter that transmits a cross-carrier RACH in the carrier including the unlicensed band; and

a receiver that receives a random access response that is transmitted from the radio base station having received the cross-carrier RACH,

wherein after the random access response is received, the radio communication terminal carries out a connection request procedure in a licensed band carrier which is the connecting carrier, and establishes a connection with the radio base station using the licensed band carrier.

2. The radio communication terminal according to claim 1, wherein the cross-carrier RACH is a signal that is formed with at least one of a cyclic prefix, a preamble, a control field, a data field and a guard time.

3. The radio communication terminal according to claim 1, wherein the cross-carrier RACH has a frame configuration that is stipulated in IEEE 802.11 series.

4. The radio communication terminal according to claim 1, wherein, before the cross-carrier RACH is transmitted, the receiver receives information about capability of random access using the cross-carrier RACH and an unlicensed band where the cross-carrier RACH is transmitted.

5. The radio communication terminal according to claim 4, wherein the information about the capability of random access using the cross-carrier RACH and the unlicensed band where the cross-carrier RACH is transmitted, is transmitted on a carrier of a licensed band.

6. The radio communication terminal according to claim 4, wherein the information about the capability of random access using the cross-carrier RACH and the unlicensed band where the cross-carrier RACH is transmitted, is transmitted on the carrier including the unlicensed band.

7. The radio communication terminal according to claim 1, wherein the random access response is transmitted on the carrier of the licensed band.

8. The radio communication terminal according to claim 1, wherein the random access response is transmitted on the carrier including the unlicensed band.

9. A radio base station that communicates with a radio communication terminal by using an unlicensed band, the radio base station comprising:

a receiver that receives a cross-carrier RACH, which the radio communication terminal transmits on a carrier that is different from a carrier where the radio communication terminal connects with, and includes an unlicensed band; and

a transmitter that, after the cross-carrier RACH is received, transmits the random access response on the carrier of the licensed band,

wherein after the random access response is transmitted, the radio communication terminal carries out a connection request procedure in a licensed band carrier which is the connecting carrier, and establishes a connection with the radio base station using the licensed band.

10. A radio communication method for a radio communication terminal that communicates with a radio base station by using a carrier that is different from a connecting carrier and includes an unlicensed band, the radio communication method comprising the steps of:

transmitting a cross-carrier RACH in the carrier including the unlicensed band; and

receiving a random access response that is transmitted from the radio base station having received the cross-carrier RACH,

wherein after the random access response is received, the radio communication terminal carries out a connection request procedure in a licensed band carrier which is the connecting carrier, and establishes a connection with the radio base station using the licensed band carrier.