Non-transparent data transmission in a digital telecommunications system

• US 5,920,545 A
• Filed: 01/06/1997
• Issued: 07/06/1999
• Est. Priority Date: 05/09/1995
• Status: Expired due to Term

• Current Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Original Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Inventors: Kanerva, Mikko, Kari, Hannu, Hamalainen, Jari, Vainikka, Jari, Rasanen, Juha
• Primary Examiner(s): Zimmerman, Brian
• Assistant Examiner(s): Beaulieu, Yonel
• Application Number:
  US08/765,059
• Time in Patent Office: 911 Days
• Field of Search: 370/232, 370/345, 370/347, 370/349, 370/229, 370/235, 370/236, 371/32, 371/33, 371/34, 375/233, 395/200.56
• US Class Current: 370/232
• CPC Class Codes: H04L 1/1809 Selective-repeat protocols
• CPC Class Codes: H04L 1/1819 with retransmission of additional or different redundancy

Abstract

A digital telecommunications system and method for non-transparent data transmission includes a non-transparent data connection between a transmitting party and a receiving party, on which channel coding is employed. The transmission buffer buffers the data frames to be transmitted and stores the transmitted data frames until it receives an acknowledgement of successful reception. This is avoided by monitoring the quality of the non-transparent connection, and if the quality of the the connection drops to a specific threshold value, by changing the channel coding scheme of the connection for a more efficient one. Simultaneously, however, more channel capacity is allocated for the connection in according with the chosen channel coding scheme so that the original nominal user data rate can be maintained unchanged or nearly unchanged.

Claims

1. A method for non-transparent data transmission in a digital telecommunications system, comprising:

establishing a non-transparent data connection having a nominal data rate, a first transmission capacity and a first channel coding scheme;

transmitting data over the non-transparent data connection in data frames using a communication protocol that acknowledges received correct data frames and re-transmits received defective data frames;

buffering the data frames to be transmitted in a transmission buffer;

storing a transmitted data frame in the transmission buffer in case of possible re-transmission, until an acknowledgement of successful reception is received;

monitoring a throughput of the non-transparent data connection on a basis of a number of re-transmissions; and

requesting additional transmission capacity and a more efficient channel coding scheme for said data connection if the throughput of the data connection drops to a predetermined threshold value.

2. A method as defined in claim 1, comprising:

monitoring a fill level of the transmission buffer; and

requesting additional transmission capacity and the more efficient channel coding scheme for said data connection if the throughput of the data connection drops to the predetermined first threshold value and the fill level of the transmission buffer reaches a predetermined threshold level.

3. A method as defined in claim 2, comprising:

maintaining the first channel coding scheme if a requested additional channel capacity is not available; and

repeating the request for more additional transmission capacity and the more efficient channel coding scheme at regular time intervals if the throughput of the data connection does not increase from said predetermined first threshold value and if the fill level of the transmission buffer does not decrease from said predetermined threshold level,

changing the channel coding scheme for the more efficient channel coding scheme without allocating more transmission capacity if the throughput of the data connection decreases to a predetermined second threshold level which is lower than the predetermined first threshold value.

4. A method as defined in claim 1, comprising:

changing the more efficient channel coding scheme for the data connection; and

allocating additional transmission capacity for the data connection corresponding to the more efficient channel coding scheme so that an original nominal user rate remains unchanged or nearly unchanged.

5. A method as defined in claim 1, comprising:

maintaining the first transmission capacity and the first channel coding scheme if the requested additional transmission capacity is not available, which capacity is required with the more efficient channel coding scheme for maintaining an original nominal user rate unchanged or nearly unchanged.

6. A method as defined in claim 4, comprising:

maintaining the first channel coding scheme if the requested additional transmission capacity is not available,

reducing said predetermined first threshold value for the throughput,

requesting additional transmission capacity and the more efficient channel coding scheme for said data connection if the throughput of the data connection drops to said reduced threshold value and if the fill level of the transmission buffer has not decreased below said predetermined threshold value.

7. A method as defined in claim 1, comprising allocating one or more traffic channels to the data connection as additional transmission capacity.

8. A digital telecommunications system comprising a transmitting party having a transmission buffer, a receiving party, a non-transparent circuit switched data connection between the transmitting party and a receiving party, channel coding means on said data connection, and a communication protocol in which data is transmitted over said data connection in data frames so that received correct data frames are acknowledged and received defective data frames are retransmitted, said transmission buffer buffering data frames to be transmitted and storing the transmitted data frames until it receives an acknowledgement of successful reception, wherein the transmitting party or a receiving party is arranged to monitor a throughput of the non-transparent data connection on a basis of a number of re-transmissions, and that the transmitting or the receiving party is arranged to request additional transmission capacity and a more efficient channel coding scheme for the data connection in question if the throughput of the data connection drops to a predetermined threshold-value.

9. A system as defined in claim 8, wherein the transmitting party is arranged to monitor a fill level of the transmission buffer, and that the transmitting party is arranged to request more transmission capacity and a more efficient channel coding scheme for said data connection if the throughput of the data connection drops to the predetermined first threshold value and the fill level of the transmission buffer increases to the predetermined threshold value.

10. A system as defined in claim 8, wherein an amount of the requested additional transmission capacity is such that an original nominal user data rate remains unchanged or nearly unchanged after changing for the more efficient channel coding scheme.

11. A system as defined in claim 8, wherein the the digital telecommunications system is a multiple access mobile communication system in which the data connection comprises one traffic channel on a radio path, and that increasing the transmission capacity of the data connection includes changing a half-rate traffic channel for a full-rate traffic channel.

12. A system as defined in claim 8, wherein the digital telecommunications system is a multiple access mobile communication system in which the data connection comprises one traffic channel or a plurality of traffic channels on a radio path, and that increasing a transmission capacity of the data connection includes increasing a number of traffic channels allocated for the data connection.

13. A system as defined in claim 8, wherein the transmitting party is a terminal adaptation function of a mobile station, and the receiving party is an interworking function (IWF) of a mobile communication network.

14. A system as defined in 8, wherein the transmitting party is an interworking function of a mobile communication network, and the receiving party is a terminal adaptation function of a mobile station.