RANDOM ACCESS METHOD USING NDI AND USER EQUIPMENT FOR THE SAME

• US 20110305197A1
• Filed: 02/03/2010
• Published: 12/15/2011
• Est. Priority Date: 02/06/2009
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Park, Sung Jun, Yi, Seung June, Chun, Sung Duck
• Granted Patent: US 9,178,662 B2
• Time in Patent Office: Days
• US Class Current: 370/328
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 1/1822 involving configuration of automatic repeat request [ARQ] with parallel processes
• CPC Class Codes: H04L 1/1896 ARQ related signaling
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 72/12 Wireless traffic scheduling
• CPC Class Codes: H04W 74/002 Transmission of channel access control information
• CPC Class Codes: H04W 74/0833 Random access procedures, e.g. with 4-step access
• CPC Class Codes: H04W 8/26 Network addressing or numbering for mobility support

Abstract

A random access method for preventing unnecessary uplink (UL) signal transmission using a New Data Indicator (NDI) and a user equipment for the same are disclosed. In the random access procedure, in order to prevent unnecessary transmission when a user equipment erroneously recognizes a UL grant signal transmitted using a cell identifier (C-RNTI) of another user equipment as a UL grant signal transmitted using its temporary cell identifier (temporary C-RNTI), toggling of an NDI indicating whether new data is transmitted may be used in a Hybrid Automatic Repeat reQuest (HARQ) system. In addition, determination as to whether or not the UL grant signal received during the random access procedure is different from that of a HARQ process used for transmission of a third message (Msg3) may be used.

Claims

1. A method of performing random access to a base station by a user equipment in a mobile communication system, the method comprising:

transmitting a random access preamble to the base station;

receiving a random access response message including a first type identifier;

transmitting an uplink (UL) message indicated by the first type identifier by a first Hybrid Automatic Repeat reQuest (HARQ) process according to the reception of the random access response message;

setting a New Data Indicator (NDI) value corresponding to the first HARQ process to a first value;

receiving a downlink (DL) message indicated by the first type identifier and including an NDI having a second value and a UL grant signal; and

considering the random access as not successful if the first value and the second value of the NDIs are different from each other.

2. The method of claim 1, wherein the mobile communication system is a synchronous HARQ system, and

wherein the method further includes considering the random access as not successful if the UL grant signal of the DL message is received at a time point corresponding to a second HARQ process.

3. The method of claim 1, wherein the receiving of the DL message includes:

receiving a Physical Downlink Control Channel (PDCCH) signal indicated by the first type identifier; and

receiving the DL message through a Physical Downlink Shared Channel (PDSCH) transmitted through a resource area according to the PDCCH information.

4. The method of claim 3, wherein the UL message includes a Medium Access Control (MAC) Packet Data Unit (PDU) including a second type identifier of the user equipment.

5. The method of claim 4, wherein the first type identifier is a temporary cell identifier (Cell Radio Network Temporary Identifier (temporary C-RNTI)) and the second type identifier is a cell identifier (C-RNTI).

6. The method of claim 5, wherein, if the first value and the second value of the NDIs are different from each other, the temporary cell identifier (temporary C-RNTI) indicated by the DL message is a cell identifier (C-RNTI) of another user equipment other than the user equipment.

7. The method of claim 5, wherein the user equipment has the cell identifier (C-RNTI) before starting random access, and

wherein the user equipment considers the random access as successful if the PDCCH signal indicated by the cell identifier of the user equipment is received after transmitting the UL message.

8. The method of claim 1, further comprising discarding the first type identifier if the random access is considered as not successful.

9. The method of claim 1, further comprising ignoring the UL grant signal if the random access is considered as not successful.

10. A user equipment for performing random access to a base station in a mobile communication system, the user equipment comprising:

a physical layer module including a transmission module for transmitting an uplink (UL) signal including a random access preamble to the base station and a reception module for receiving a downlink (DL) signal including a random access response message including a first type identifier; and

a Medium Access Control (MAC) layer module configured to control a plurality of Hybrid Automatic Repeat reQuest (HARQ) processes and to control determination as to whether or not the random access is successful and whether or not the UL signal is transmitted, depending on whether or not a New Data Indicator (NDI) value stored in each of a plurality of HARQ buffers corresponding to the plurality of HARQ processes is toggled,

wherein, if the physical layer module receives the random access response message including the first type identifier, the MAC layer module controls a UL message indicated by the first type identifier to be transmitted by a first HARQ process and sets the NDI value corresponding to the first HARQ process to a first value, and

wherein, if the physical layer module receives a DL message indicated by the first type identifier and including an NDI having a second value and a UL grant signal, the MAC layer module determines whether the first value and the second value of the NDIs are equal to each other, and considers the random access as not successful if the first value and the second value are different from each other.

11. The user equipment of claim 10, wherein the mobile communication system is a synchronous HARQ system, and

if the UL grant signal of the DL message is received at a time point corresponding to a second HARQ process, the MAC layer module considers the random access as not successful.

12. The user equipment of claim 10, wherein a Physical Downlink Control Channel (PDCCH) signal indicated by the first type identifier is received and the DL message is received through a Physical Downlink Shared Channel (PDSCH) transmitted through a resource area according to the PDCCH information.

13. The user equipment of claim 12, wherein the UL message includes a Medium Access Control (MAC) Packet Data Unit (PDU) including the second type identifier of the user equipment.

14. The user equipment of claim 13, wherein the first type identifier is a temporary cell identifier (Cell Radio Network Temporary Identifier (temporary C-RNTI)) and the second type identifier is a cell identifier (C-RNTI).

15. The user equipment of claim 14, wherein, if the user equipment has the cell identifier (C-RNTI) before starting random access and the user equipment receives the PDCCH indicated by the cell identifier after transmitting the UL message, the user equipment considers the random access as not successful.

16. The user equipment of claim 10, wherein the MAC layer module is configured to discard the first type identifier if the random access is considered as not successful.

17. The user equipment of claim 10, wherein the MAC layer module is configured to ignore the UL grant signal if the random access is considered as not successful.