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System and Method of Filtering MRWs, ACKs and NACKs after RLC Re-Establishment

IP.com Disclosure Number: IPCOM000130514D
Publication Date: 2005-Oct-25
Document File: 2 page(s) / 10K

Publishing Venue

The IP.com Prior Art Database

Abstract

In a wireless communication systems such as UMTS, radio-bearer characteristics sometimes changes during the course of a connection. When certain radio-bearer parameter changes a reestablishment of the RLC entity is required. The RLC re-establishment is made in such a way that there should be a minimum of data loss between the RLC peers.

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DATA FILTERING TECHNIQUE

System and Method of Filtering MRWs, ACKs and NACKs after RLC
Re-Establishment

Disclosed Anonymously

In a wireless communication systems such as UMTS, radio-bearer characteristics sometimes changes during the course of a connection. When certain radio-bearer parameter changes a reestablishment of the RLC entity is required. The RLC re-establishment is made in such a way that there should be a minimum of data loss between the RLC peers.

The UTRAN can order the UE to perform re-establishment immediately or later at a specified time. During a RLC re-establishment, the RLC sequence numbers for receiver and transmitter part are reset to zero.

A possible scenario for immediate re-establishment is as follows:

1. UTRAN stops all downlink transmission.

2. UTRAN signals to the UE to perform re-establishment.

3. The UE performs the re-establishment.

4. The UE signals to UTRAN that the re-establishment is complete.

5. UTRAN re-establishes the RB.

6. UTRAN starts the downlink transmission.

A possible scenario for delayed re-establishment is as follows:

1. UTRAN signals to the UE to perform re-establishment with delay.

2. The UE signals to UTRAN that the re-establishment will be made.

3. At activation time both UE and UTRAN re-establishes the RB.

When the RLC entity is re-established, all Data PDUs and Control PDUs are discarded.

The problem occurs in UTRAN RLC in the case where the UE RLC has transmitted either one of the following messages immediately prior to reestablishment (as data PDUs and Control PDUs that was already given to MAC/L1 for transmission will not be discarded):

1. STATUS PDU with Acknowledgement (ACK).

2. STATUS PDU with Negative Acknowledgement (NACK).

3. STATUS PDU with Move Receiver Window (MRW).

If either of those messages are received immediately after UTRAN RLC has performed the re-establishment, the following events can happen:

1. UTRAN RLC triggers the RLC reset procedure as the sequence number does not match the expected sequence numbers after re-establishment (for case 1 and 2. See 25.322 10.1). This will lead to additional RLC signalling and possible loss of user dat...