Trogir

Trogir (Latin: Tragurium; Italian: Traù; Ancient Greek: Τραγύριον, Tragyrion or Τραγούριον, TragourionTrogkir) is a historic town and harbour on the Adriatic coast in Split-Dalmatia County, Croatia, with a population of 10,818 (2011) and a total municipality population of 13,260 (2011). The historic city of Trogir is situated on a small island between the Croatian mainland and the island of Čiovo. It lies 27 kilometres (17 miles) west of the city of Split.

Since 1997, the historic centre of Trogir has been included in the UNESCO list of World Heritage Sites.

History

In the 3rd century BC, Tragurion was founded by Greek colonists from the island of Vis, and it developed into a major port until the Roman period. The name comes from the Greek "tragos" (male goat). Similarly, the name of the neighbouring island of Bua comes from the Greek "voua" (herd of cattle). The sudden prosperity of Salona deprived Trogir of its importance. During the migration of Croats the citizens of the destroyed Salona escaped to Trogir. Initially the Roman Tragurium was one of the Dalmatian City-States. From the 9th century on, Trogir paid tribute to Croatian rulers and to the Byzantine empire. The diocese of Trogir was established in the 11th century (abolished in 1828; it is now part of the Roman Catholic Archdiocese of Split-Makarska and has temporarily been a Latin titular bishopric) and in 1107 it was chartered by the Hungarian-Croatian king Coloman, gaining thus its autonomy as a town.

TRAU

Transcoder and Rate Adaptation Unit, or TRAU, performs transcoding function for speech channels and RA (Rate Adaptation) for data channels in the GSM network. The Transcoder/Rate Adaptation Unit (TRAU) is the data rate conversion unit. The PSTN/ISDN switch is a switch for 64 kbit/s voice. Current technology permits to decrease the bit-rate (in GSM radio interface it is 13 kbit/s for full rate and 6.5 kbit/s for half rate). Since MSC is basically a PSTN/ISDN switch its bit-rate is still 64 kbit/s. That is why a rate conversion is required in between the BSC and MSC...

Transcoding is the compression of speech data from 64 kbit/s to 13/12.2/6.5 kbit/s in case FR/EFR/HR (respectively) speech coding.

Rate adaptation without transcoding allows Tandem Free Operation (TFO), allowing the original encoded speech data to be carried in a 64 kbit/s channel. TFO offers benefits because transcoding can lead to a degradation of speech quality and requires computational resources.

Brief Explanation

For an MS-to-MS call, the transmission path covers the radio access network (RAN) as well as the core network (CN). Since the transmission modes and coding standards are different for RAN and CN, speech data is converted/transcoded at the transition points from RAN to CN. This conversion is performed in the TRAU network element which connects RAN and CN.