Combined tracking method for timing deviation and sampling frequency offset

A technology of sampling frequency deviation and timing deviation, which is applied in the direction of multi-frequency code system and so on

Active Publication Date: 2011-05-25
MAXSCEND MICROELECTRONICS CO LTD
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Problems solved by technology

This method is suitable for OFDM systems using time-frequency two-dimensional pilot structure, but it needs to increase certain storage resources to store the channel frequency domain response information at the previous moment

Method used

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  • Combined tracking method for timing deviation and sampling frequency offset
  • Combined tracking method for timing deviation and sampling frequency offset
  • Combined tracking method for timing deviation and sampling frequency offset

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Embodiment Construction

[0018] see figure 1 As shown, according to the protocol definition of CMMB, its physical layer signal is based on a physical frame, and the frame length is 1 second. Each physical frame signal is divided into 40 time slots, and each time slot is 25 milliseconds long. Two known synchronization signals are fixedly sent at the beginning of each time slot signal, and the synchronization signals are used to carry service data afterwards. Each service can occupy multiple time slots to send service data, and occupy the same spectrum resources in a time-division manner to send broadcast services. The physical frame definition of this time-division multiplexing is beneficial to the receiver to flexibly select the time-slot signal to be received in multiple time-slot signals by using the time-slot switching technology (Timing Slice), and keep silent on other time-slot signals to reduce the receiver power consumption. But at the same time, the requirements for the timing deviation tra...

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Abstract

The present invention discloses a combined tracking method for timing deviation and sampling frequency offset, which is suitable for a digital mobile multimedia broadcasting system. The method comprises the steps of: according to channel impulse response information obtained by estimation, firstly estimating timing deviation for OFDM symbols and determining timing adjusting information for the next time slot; and then estimating sampling frequency offset according to the position information of the strongest path in the channel impulse response and the timing adjusting information for the last time slot, thereby realizing the combined adjusting of the timing deviation and the sampling frequency offset. The combined tracking method of the invention can not only track a symbol timing error brought by multipath distribution characteristic of a transmission channel, but also track and correct the sampling frequency offset brought by the inconsistency between two local oscillators for transmitting and receiving terminals; stable operation can also be realized even in the time division working mode of a receiver and the receiver can stably work by flexibly changing the estimation size of the sampling frequency offset according to the length of the time division working time of the receiver.

Description

technical field [0001] The invention relates to the field of wireless signal transmission, in particular to a joint tracking method for timing deviation and sampling frequency deviation suitable for digital mobile multimedia broadcasting systems. Background technique [0002] For an OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing) system, both timing synchronization and sampling frequency synchronization are one of its core technologies. Because the OFDM system introduces a cyclic prefix as a guard interval, the OFDM system has looser requirements on timing synchronization. As long as the starting position of the FFT (Fast Fourier Transform) operation window is guaranteed to vary only within the range of the cyclic prefix, no inter-symbol interference (ISI) will be introduced. However, in a wireless propagation environment, due to the existence of surrounding scatterers, wireless signals usually reach the receiver through multipl...

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Application Information

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IPC IPC(8): H04L27/26
Inventor 程鑫豪金方其陈肯
Owner MAXSCEND MICROELECTRONICS CO LTD
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