Telecommunications transmission systems

US7526021B2 · kind B2 · utility

Assignee

• STMicroelectronics SA

Inventors

• Magnus Johansson · Luleå, SE
• Lennart Olsson · Luleå, SE
• Gunnar Bahlenberg · Luleå, SE
• Daniel Bengtsson · Luleå, SE
• Mikael R. Isakssaon · Luleå, SE
• Sven-Rune Olofsson · Älvsbyn, SE
• Sven Göeran Öekvist · Luleå, SE

Key dates

• Filing date: May 17, 2006
• Grant date: Apr 28, 2009
• Expiry date: May 1, 2027

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04L2025/03617
• WIPO field: Digital communication
• WIPO sector: Electrical engineering

Abstract

In a multi-carrier system employing OFDM, for example DMT, an adaptive channel equalizer is normally used, operating in the frequency domain. The sampling clock is controlled so that the time delay between the transmitter and the receiver is effectively eliminated. If the information used to control the sampling clock is received from the equalized data stream, it will introduce an ambiguity between the operation of the channel equalizer and the mechanism used to control the sampling clock. Operation of the equalizer can mask an increasing time difference, between transmitter and receiver, which the sample clock controller should be tracking. The present invention eliminates the ambiguities in the operation of the equalizer and sample clock controller by preventing the equalizer accepting time differences which should be corrected by operation of the sample clock controller.