# US 9,521,599 B2 · Dynamic transport channel synchronization

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- Number: US 9,521,599 B2
- Document ID: US9521599B2
- Status: Granted
- Kind: B2
- Application number: 14/440,017
- Filed: 2012-10-31
- Published: 2015-10-01
- Granted: 2016-12-13
- Earliest claimed: 2012-10-31
- Assignees: Telefonaktiebolaget LM Ericsson (publ)
- Applicants: Telefonaktiebolaget LM Ericsson (publ)
- Inventors: Aleksandar Jovanovic; Johan Magnusson; Fredrik Sonnevi
- Web page: https://patentgrep.com/patent/US9521599B2

## CPC

- H04W 36/02: Buffering or recovering information during reselection {; Modification of the traffic flow during hand-off}
- H04W 56/0045: {compensating for timing error by altering transmission time}
- H04W 92/12: between access points and access point controllers
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

The present invention relates to a method of, and device in the form of a radio access network supervising entity for, adapting to delay in a communication link established between the radio access network supervising entity and at least one radio base station communicating with a mobile terminal. The method comprises associating a target Connection Frame Number (CFN) to each transmitted data frame, said target CFN being calculated by offsetting an expected CFN with a counter value corresponding to a current communication link delay, repeatedly determining delay of the communication link, and adapting to the delay of the communication link by adjusting transmission time of the transmitted frame, and/or adjusting the target CFN of the transmitted frame, said target CFN being calculated by offsetting the expected CFN with a counter value corresponding to a determined new delay.

## Claims

### Claim 1

A method at a radio access network supervising entity, of adapting to delay in a communication link established between the radio access network supervising entity and at least one radio base station communicating with a mobile terminal, the method comprising:
associating a target Connection Frame Number (CFN) to each transmitted data frame, said target CFN being calculated by offsetting an expected CFN with a counter value corresponding to a current communication link delay associated with a first communication link between the radio access network supervising entity and a first radio base station communicating with the mobile terminal;
determining delay of the first communication link;
adapting to the delay of the first communication link by adjusting transmission time of the transmitted data frame or adjusting the target CFN of the transmitted data frame, said target CFN being calculated by offsetting the expected CFN with a counter value corresponding to the determined delay;
establishing a second communication link between the radio access network supervising entity and a second radio base station;
determining delay for each of the first and second communication links;
identifying a greatest delay from the determining of the delay of each of the first and second communication links; and
adapting delay of each of the first and second communication links by advancing the transmission time of the transmitted data frame to reflect the greatest delay or by advancing the target CFN to reflect the greatest delay.

### Claim 2 (depends on 1)

The method of claim 1, wherein the second communication link is established between the radio access network supervising entity and the second radio base station for performing handover of the mobile terminal.

### Claim 3 (depends on 1)

The method of claim 1, wherein transmission of a particular data frame over radio base station air interface is enabled when the expected CFN equals a target CFN associated with said particular data frame.

### Claim 4 (depends on 2)

The method of claim 2, wherein the delay of each communication link is adapted by advancing the transmission time of the transmitted data frame to reflect the greatest delay, if a difference between the greatest delay and the delay of the communication link to be adapted is less than a Transmission Time Interval (TTL).

### Claim 5 (depends on 2)

The method according to claim 2, wherein, in case one of the radio base stations having the communication link with the greatest delay is no longer to be involved in the handover of the mobile terminal, the delay to be adapted is adapted by reducing the target CFN to reflect a greatest delay of a remaining communication link.

### Claim 6 (depends on 5)

The method according to claim 5, further comprising:
buffering data frames received from a core network until the target CFN has reached a value exceeding a target CFN that was current at a point in time when the radio base station having the communication link with the greatest delay no longer was to be involved in the handover of the mobile terminal.

### Claim 7 (depends on 6)

The method according to claim 6, further comprising:
discarding the buffered data frames received from the core network in case the data frames relate to speech data.

### Claim 8

A device configured to be a radio access network supervising entity, for adapting to delay in a communication link established between the device and at least one radio base station communicating with a mobile terminal, the device comprising a processing unit being arranged to:
associate a target Connection Frame Number (CFN) to each transmitted data frame, said target CFN being calculated by offsetting an expected CFN with a counter value corresponding to a current communication link delay associated with a first communication link between the device and a first radio base station communicating with the mobile terminal;
determine delay of the first communication link;
adapt to the delay of the first communication link by adjusting transmission time of the transmitted data frame or adjusting the target CFN of the transmitted data frame, said target CFN being calculated by offsetting the expected CFN with a counter value corresponding to the determined delay
establish a second communication link between the device and a second radio base station;
determine delay for each of the first and second communication links;
identify a greatest delay from determining of the delay of each of the first and second communication links; and
adapt delay of each of the first and second communication links by advancing the transmission time of the transmitted data frame to reflect the greatest delay or by advancing the target CFN to reflect the greatest delay.

### Claim 9 (depends on 8)

The device of claim 8, wherein the second communication link is established between the device and the second radio base station for performing handover of the mobile terminal.

### Claim 10 (depends on 8)

The device of claim 8, wherein transmission of a particular data frame over radio base station air interface is enabled when the expected CFN equals a target CFN associated with said particular data frame.

### Claim 11 (depends on 9)

The device of claim 9, wherein the delay of each communication link is adapted by advancing the transmission time of the transmitted data frame to reflect the greatest delay, if a difference between the greatest delay and the delay of the communication link to be adapted is less than a Transmission Time Interval (TTL).

### Claim 12 (depends on 9)

The device according to claim 9, wherein, in case one of the radio base stations having the communication link with the greatest delay is no longer to be involved in the handover of the mobile terminal, the delay to be adapted is adapted by reducing the target CFN to reflect a greatest delay of a remaining communication link.

### Claim 13 (depends on 12)

The device according to claim 12, wherein the processing unit is further being arranged to:
buffer data frames received from a core network until the target CFN has reached a value exceeding a target CFN that was current at a point in time when the radio base station having the communication link with the greatest delay no longer was to be involved in the handover of the mobile terminal.

### Claim 14 (depends on 13)

The device according to claim 13, wherein the processing unit is further being arranged to:
discard the buffered data frames received from the core network in case the data frames relate to speech data.

### Claim 15 (depends on 8)

The device according to claim 8, wherein said device is a radio network controller (RNC).

### Claim 16

A non-transitory machine-readable storage medium having computer code stored therein, which when executed by a set of one or more processors of a device configured to be a radio access network supervising entity, for adapting to delay in a communication link established between the device and at least one radio base station communicating with a mobile terminal, causes the device to perform operations comprising:
associating a target Connection Frame Number (CFN) to each transmitted data frame, said target CFN being calculated by offsetting an expected CFN with a counter value corresponding to a current communication link delay associated with a first communication link between the radio access network supervising entity and a first radio base station communicating with the mobile terminal;
determining delay of the first communication link;
adapting to the delay of the first communication link by adjusting transmission time of the transmitted data frame or adjusting the target CFN of the transmitted data frame, said target CFN being calculated by offsetting the expected CFN with a counter value corresponding to the determined delay;
establishing a second communication link between the radio access network supervising entity and a second radio base station;
determining delay for each of the first and second communication links;
identifying a greatest delay from the determining of the delay of each of the first and second communication links; and
adapting delay of each of the first and second communication links by advancing the transmission time of the transmitted data frame to reflect the greatest delay or by advancing the target CFN to reflect the greatest delay.