| 摘要 |
An apparatus is described which can increase the time before a call is dropped in weak signal areas. The apparatus comprises a processor which is configured to determine whether voice and/or video data is in the process of transmission and/or reception; and select the last transmitted Packet Data Unit for polling transmission in response to a polling event if it is determined that that voice and/or video data is in the process of transmission and/or reception. When applied to UMTS and. E-UTRA protocols, the last transmitted packet data unit has a sequence number equal to VT(S)-1. It has been found that voice and/or video calls may be dropped in weak signal areas because of a reset triggered for the Acknowledged Mode bearer within the Radio Link Control (RLC). The reset occurs because the same Packet Data Unit was selected for a polling transmission several times and triggered the reset by reaching its maximum transmission count. By selecting the last transmitted packet data unit, the packet data unit selected for polling transmission will change over time, increasing the time before a single packet data unit reaches its maximum transmission count. Although voice and video calls typically do not use A M, AM is used on the control and signalling channel and this has been found to be the cause of the reset.
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