ERROR DETECTION

1 . A method of enabling ciphering error detection and recovery in a telecommunications network, the method comprising, at a network entity:

inserting predetermined data into at least one radio link control service data unit; and

transmitting the at least one radio link control service data unit comprising the predetermined data to a user equipment in the network,

whereby the user equipment is able to apply, on the basis of the predetermined data, either an unacknowledged mode radio link control ciphering error detection and recovery mechanism or a packet data convergence protocol ciphering error detection and recovery mechanism to the at least one radio link control service data unit.

2 . A method according to claim 1 , wherein the predetermined data has the same form as a packet data convergence protocol header.

3 . A method according to claim 1 , wherein the predetermined data is inserted into a header part of the at least one radio link control service data unit.

4 . A method according to claim 1 , wherein the predetermined data is inserted into a new field of at least one radio link control protocol data unit generated from at least a first part of the at least one radio link control service data unit.

5 . A method according to claim 4 , wherein the new field comprises a new parity field added to said at least one radio link control protocol data unit.

6 . A method according to claim 4 , wherein the new field is added into the at least one radio link control protocol data unit next to user data of the at least one radio link control protocol data unit.

7 . A method according to claim 4 , wherein the new field is added into the at least one radio link control protocol data unit next to a length indicator field of the at least one radio link control protocol data unit.

8 . A method according to claim 1 , comprising generating a plurality of radio link control protocol data units from the at least one radio link control service data unit,

wherein the predetermined data is inserted into a first radio link control protocol data unit in the plurality of radio link control protocol data units.

9 . A method according to claim 2 , comprising configuring a dummy packet data convergence protocol layer to carry out the insertion of the predetermined data having the same form as a packet data convergence protocol header into the at least one radio link control service data unit.

10 . A method according to claim 9 , wherein the dummy packet data convergence protocol layer is configured in a radio link control entity of the network entity.

11 . A method according to claim 1 , wherein the at least one radio link control service data unit is associated with an Internet Protocol Multimedia Subsystem (IMS) voice service or a circuit-switched voice communication over High Speed Packet Access (CSoHSPA) service.

12 . A method according to claim 1 , wherein the predetermined data is defined via radio resource control signalling between network entity and the user equipment.

13 . Apparatus for use in enabling ciphering error detection and recovery in a telecommunications network, the apparatus comprising at least one processor and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus at least to, at a network entity:

insert predetermined data into at least one radio link control service data unit; and

transmit the at least one radio link control service data unit comprising the predetermined data to a user equipment in the network,

whereby the user equipment is able to apply, on the basis of the predetermined data, either an unacknowledged mode radio link control ciphering error detection and recovery mechanism or a packet data convergence protocol ciphering error detection and recovery mechanism to the at least one radio link control service data unit.

14 . A method of enabling ciphering error detection and recovery in a telecommunications network, the method comprising, at a user equipment:

receiving at least one radio link control service data unit comprising predetermined data; and

applying, on the basis of the predetermined data, either an unacknowledged mode radio link control ciphering error detection and recovery mechanism or a packet data convergence protocol ciphering error detection and recovery mechanism to the at least one received radio link control service data unit.

15 . A method according to claim 14 , wherein the predetermined data has the same form as a packet data convergence protocol header.

16 . A method according to claim 14 , wherein the receiving comprises receiving a plurality of radio link control service data units, and

wherein the applying comprises applying the unacknowledged mode radio link control ciphering error detection and recovery mechanism to the plurality of radio link control service data units, the method comprising:

in response to the applying detecting one or more errors in the predetermined data in a given number of consecutive radio link control service data units in the plurality of radio link control service data units, initiating a recovery procedure for a radio link control unrecoverable error.

17 . A method according to claim 16 , wherein the initiating comprises:

initiating a CellUpdate procedure; or

initiating radio link control or packet data convergence protocol error reporting in the network.

18 . A method according to claim 17 , wherein initiating the radio link control or packet data convergence protocol error reporting comprises transmitting an uplink radio resource control message to a network entity in the network.

19 . A method according to claim 18 , wherein the uplink radio resource control message comprises a SignallingConnectionReleaseIndication message.

20 . Apparatus for use in enabling ciphering error detection and recovery in a telecommunications network, the apparatus comprising at least one processor and at least one memory including computer program code, the at least one memory and the computer program code being configured to, with the at least one processor, cause the apparatus at least to, at a user equipment:

receive at least one radio link control service data unit comprising predetermined data; and

apply, on the basis of the predetermined data, either an unacknowledged mode radio link control ciphering error detection and recovery mechanism or a packet data convergence protocol ciphering error detection and recovery mechanism to the at least one received radio link control service data unit.