1. Field of the Invention
The present invention relates in general to a third generation cellular system and, in particular, to a radio base station (RBS) that can detect when a high-speed downlink shared channel (HS-DSCH) data frame is lost after it was transmitted from a radio network controller (RNC) on a transport link (Iub) towards the RBS.
2. Description of Related Art
Today there is a high level of interest in enhancing the performance of a third generation cellular system that implements the high-speed-downlink-packet-access (HSDPA) provision of the Wideband Code Division Multiple Access (WCDMA) standard. The performance of the third generation cellular system could be enhanced if there was a way to detect when a data frame (HS-DSCH data frame) is lost after it was sent from a radio network controller (RNC) on a transport link (“Iub”) towards a radio base station (RBS).
It would be desirable to be able to detect lost HS-DSCH data frames, because if too many HS-DSCH data frames are lost and never received by the RBS then this would result in retransmissions between the RNC and a UE (user equipment such as a mobile handset or terminal). The retransmission of information between the RNC and the UE is not desirable because it reduces the HSDPA throughput. Unfortunately, the traditional RBS does not have a way to detect when there is a lost HS-DSCH data frame so it is not able to prevent the problematical retransmissions between the RNC and the UE. This shortcoming is addressed by the present invention.