RANDOM ACCESS PREAMBLE COLLISION DETECTION

• US 20100220713A1
• Filed: 11/05/2008
• Published: 09/02/2010
• Est. Priority Date: 11/05/2007
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Tynderfeldt, Tobias, Lindström, Magnus
• Granted Patent: US 8,411,664 B2
• Time in Patent Office: Days
• US Class Current: 370/350
• CPC Class Codes: H04W 56/0005 synchronizing of arrival of multiple uplinks
• CPC Class Codes: H04W 56/0045 compensating for timing error by altering transmission time

Abstract

A method (500) for a user terminal (120, 130) in a cellular system (100). The user terminal (120, 130) applies (505) a timing advance to transmissions to a controlling node (140). The user terminal (120, 130) requests (510) communication with the controlling node (140) by a special message (MSG 1), in response to which the user terminal (120, 130) receives (515) a message (MSG 2) which includes an updated value for the timing advance. The user terminal (120, 130) compares (520) the updated value with the value of the timing advance that the user terminal had prior to the reception of said response message. If the difference (Δ) between the prior value and the updated value is greater than a first predetermined threshold (T₁) or below a second predetermined threshold (T₂), the user terminal (120, 130) ignores (525) the response message (MSG 2) and renews its request for communication.

Claims

1. A method (500) for use in a user terminal (120, 130) in a cellular communications system (100), according to which method the user terminal (120, 130) applies (505) a timing advance to its transmissions to a controlling node (140), and according to which method the user terminal (120, 130) may request (510) communication with the controlling node (140) by means of a special message (MSG 1), in response to which the user terminal (120, 130) receives (515) a response message (MSG 2) which includes an updated value for the timing advance, the method (500) being characterized in that the user terminal (120, 130) compares (520) the updated value for the timing advance with the value of the timing advance that the user terminal had prior to the reception of said response message, and if the difference (Δ

) between the prior value and the updated value is greater than a first predetermined threshold (T1) or below a second predetermined threshold (T2), the user terminal (120, 130) ignores (525) the response message (MSG 2) and renews its request for communication.

2. The method (500) of claim 1, according to which the first (T1) and the second (T2) thresholds have the same absolute value, but with different signs, so that the second threshold (T2) corresponds to the first threshold (T1), but has a negative value.

3. The method (500, 530) of claim 1, according to which said first and second thresholds (T1, T2) are provided to the user terminal (120, 130) by the controlling node (140) in question.

4. The method (500, 530, 535) of claim 1, according to which the thresholds (T1, T2) are provided in a system information message.

5. The method (500, 530, 535, 540) of claim 3, according to which the thresholds (T1, T2) are provided in a broadcast message from the controlling node (140) in question.

6. The method (500, 545) of claim 1, according to which said thresholds (T1, T2) are used by all user terminals (120, 130) in the system (100), i.e. the values are system standard values.

7. The method (500, 546) of claim 1, according to which the user terminal (120, 130) renews its request for communication a certain predefined number of times, and if the difference between the prior value and the updated value exceeds the first threshold (T1) or falls below the second threshold (T2) during said number of times, the user terminal discards the prior value and uses the updated value.

8. The method (500, 550) of claim 1, according to which the user terminal (120, 130) applies a timer to the timing advance value so that the value is only valid for the duration of the timer, and according to which method the user terminal (120, 130) only makes said comparison if the prior timing advance value is valid when the updated value is received, so that the updated value is accepted otherwise.

9. A transceiver (600) for use as a user terminal in a cellular communications system (100), the transceiver being equipped with means (640, 650) for applying a timing advance to its transmissions to a controlling node (140), and with means (640, 630, 610) for requesting communication with the controlling node by means of a special message, as well as with means (610, 620, 640) for receiving a response message which includes an updated value for the timing advance, the transceiver (600) being characterized in that it comprises means (640, 650) for comparing the updated value for the timing advance with the value of the timing advance that the transceiver had prior to the reception of said response message, and with means (640, 650, 630, 610) for ignoring the response message (MSG 2) and renewing the request for communication if the difference (Δ

) between the prior value and the updated value is greater than a first predetermined threshold (T1) or below a second predetermined threshold (T2), the user terminal (120, 130).

10. The transceiver (600) of claim 9, being equipped with means (610, 620) for receiving said first and second thresholds (T1, T2) from the controlling node (140) in question.

11. The transceiver of claim 9, being equipped with means (610, 620) for receiving the thresholds (T1, T2) in a system information message.

12. The transceiver of claim 9, being equipped with means (610, 620) for receiving the thresholds (T1, T2) in a broadcast message from the controlling node (140) in question.

13. The transceiver of claim 9, which uses system values as the values of said thresholds (T1, T2).

14. The transceiver (600) of claim 9, comprising means (640, 650, 630, 610) for renewing the request for communication a certain predefined number of times, and means (640, 650) for discarding the prior value and using the updated value if the difference between the prior value and the updated value exceeds the first threshold (T₁) or falls below the second threshold (T₂) during said number of times, the user terminal

15. The transceiver of claim 9, comprising means (640, 650) for applying a timer to the timing advance value so that the value is only valid for the duration of the timer, and means (640, 650) for making said comparison if the prior timing advance value is valid when the updated value is received, so that the updated value is accepted otherwise.