METHOD AND APPARATUS FOR TRANSMITTING/RECEIVING RACH

• US 20080043771A1
• Filed: 08/20/2007
• Published: 02/21/2008
• Est. Priority Date: 08/18/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Jeong, Kyeong-In, Cho, Joon-Young, Lee, Ju-Ho, Park, Seung-Hoon, CHO, Yun-Ok
• Granted Patent: US 8,488,620 B2
• Time in Patent Office: Days
• US Class Current: 370/431
• 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 74/0866 using a dedicated channel for access

Abstract

A method and apparatus for transmitting/receiving a Random Access Channel (RACH) signal in a communication system. A User Equipment (UE) selects one of Contention Resolution (CR) channels allocated for collision detection, and transmits the selected CR channel and a connection request message to an Evolved Node B (E-NB), and receives a response signal from the E-NB. The UE transmits the RACH signal, if a collision indicator is included in the response signal. The E-NB receives from each of UEs a connection request message and a CR channel, decodes the connection request message, and detects a collision between the UEs using the CR channel. The E-NB generates a response signal to the connection request message according to the decoding result, generates a collision indicator according to the collision detection result, and transmits to the UEs at least one of the generated response signal, the generated collision indicator, and a unique ID of a corresponding UE.

Claims

1. A method for transmitting a Random Access Channel (RACH) signal by a User Equipment (UE) in a communication system, the method comprising:

selecting a Contention Resolution (CR) channel from a plurality of CR channels allocated for collision detection;

transmitting the selected CR channel and a connection request message to an Evolved Node B (E-NB), and receiving a response signal from the E-NB.

2. The method of claim 1, further comprising:

performing a new RACH procedure, if a collision indicator is included in the response signal.

3. The method of claim 1, wherein the transmitting of the selected CR channel to the E-NB comprises:

transmitting a sequence of the selected CR channel among orthogonal sequences of CR channels.

4. The method of claim 1, further comprising:

returning to the selecting of a CR channel if the response signal is a negative response signal.

5. The method of claim 1, wherein the response signal includes a unique identity (ID) of a collision detection-succeeded UE together with the collision indicator, and

wherein a UE except for the UE indicated by the unique ID, restarts the transmitting of the RACH.

6. A method for receiving a Random Access Channel (RACH) signal from User Equipments (UEs) by an Evolved Node B (E-NB) in a communication system, the method comprising:

receiving from each of the UEs a connection request message and a Contention Resolution (CR) channel allocated for collision detection;

decoding the connection request message, and detecting a collision between the UEs using the CR channel;

generating a positive/negative response signal for the connection request message according to the decoding result, and generating a collision indicator according to the collision detection result; and

transmitting to the UEs at least one of the generated response signal, the generated collision indicator, and a unique identity (ID) of a corresponding UE.

7. The method of claim 6, wherein the response signal includes the collision indicator together with a unique ID of a collision detection-succeeded UE.

8. The method of claim 6, wherein the detecting of a collision comprises:

detecting energy of a CR channel signal, and determining that a collision has occurred when there are more than two signals whose energy is greater than a threshold.

9. The method of claim 6, wherein the detecting of a collision comprises:

determining that a collision has occurred when there are more than two CR channel signals, a correlation between which is greater than a threshold.

10. An apparatus for transmitting a Random Access Channel (RACH) signal to an Evolved Node B (E-NB) in a communication system, the apparatus comprising:

a data channel generator for generating a signal transmitted over a data channel;

a Contention Resolution (CR) channel generator for generating a signal transmitted over a CR channel allocated for collision detection;

a CR channel selector for selecting one of the CR channel signals; and

a multiplexer for multiplexing the generated data channel signal and the selected CR channel signal before transmission.

11. The apparatus of claim 10, further comprising:

a controller for performing a new RACH procedure, if a collision indicator is included in the response signal.

12. The apparatus of claim 10, wherein the CR channel generator transmits a sequence of the selected CR channel among orthogonal sequences of CR channels.

13. The apparatus of claim 10, wherein the multiplexer transmits the data channel signal and the CR channel signal in different time intervals.

14. The apparatus of claim 10, wherein the multiplexer transmits the CR channel signal in more than two subcarriers in a distributed manner.

15. An apparatus for receiving a Random Access Channel (RACH) signal from User Equipments (UEs) in a communication system, the apparatus comprising:

a demultiplexer for separating, from signals received from the UEs, a connection request message, a Contention Resolution (CR) channel signal allocated for collision detection, and a data channel signal;

a collision detector for detecting a collision between the UEs from the CR channel signal, and outputting a signal indicating an occurrence of a collision;

a data channel decoder for decoding the data channel signal; and

a collision indicator generator for generating a collision indicator indicating an occurrence of a collision according to an output signal of the collision detector and success/failure in the decoding of the data channel decoder, and transmitting the collision indicator to the UEs.

16. The apparatus of claim 15, wherein the collision indicator generator transmits the collision indicator to the UEs along with a unique identity (ID) of a collision detection-succeeded UE, and transmitting the response signal.

17. The apparatus of claim 15, wherein the collision detector detects energy of a CR channel signal, and determines that a collision has occurred when there are more than two signals whose energy is greater than a threshold.

18. The apparatus of claim 15, wherein the collision detector determines that a collision has occurred when there are more than two CR channel signals, a correlation between which is greater than a threshold.