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Frequency correction in pilot symbol assisted demodulator

A technology of automatic frequency correction and pilot code, applied in automatic frequency control components, electrical components, carrier adjustment, etc.

Inactive Publication Date: 2005-09-07
TELEFON AB LM ERICSSON (PUBL)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The main disadvantage of the above solution is that it takes a long time to converge

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  • Frequency correction in pilot symbol assisted demodulator
  • Frequency correction in pilot symbol assisted demodulator
  • Frequency correction in pilot symbol assisted demodulator

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Embodiment Construction

[0052] The invention is described herein for a mobile station operating in a wireless network. But the application of this invention is not limited to mobile stations. The invention can be used in base stations or any application where automatic frequency correction is used.

[0053] figure 1 is a block diagram of a mobile station (also known as a radiotelephone, cellular telephone or cell phone), indicated generally at 10 . Mobile station 10 includes an antenna 12 for transmitting and receiving radio signals between itself and the wireless network. The antenna 12 is connected to a duplexer 14 which enables a receiver 16 and a transmitter 18 to use the same antenna 12 (respectively) for reception and broadcasting. Alternatively, a transceiver switch can be used, which switches between different transmit signal paths and receive signal paths, especially when the times of transmission and reception do not overlap. The receiver 16 demodulates, demultiplexes and decodes radio ...

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Abstract

A method for selecting a frequency offset for automatic frequency correction in a pilot symbol assisted demodulation system comprises the steps of receiving a signal comprising a plurality of symbols having discrete possible values, and pilot symbols at predetermined locations in the signal having a predetermined value. The method further includes selecting a set of postulates defining a range of frequency offsets, multiplying the pilot symbols and selected ones of the plurality of the symbols by a sinusoid of the postulates to compensate for the postulated error, and estimating the channel at the error-compensated pilot symbols. The estimated channel at the error-compensated pilot symbols is then interpolated and a metric is generated for the error-compensated pilot and the selected symbols using the symbols' discrete possible values and the interpolated estimated channel. The postulate with a minimum accumulated metric is used in demodulating the symbols.

Description

technical field [0001] The invention relates to the field of wireless communication, in particular to a wireless receiver using automatic frequency correction in the demodulation process. Background technique [0002] In a wireless communication system between a mobile station and a base station, the signal encounters various conditions that degrade the signal quality. For example, receivers typically receive signals from multiple directions (such as directly from the transmitter, and / or from various terrain and man-made obstacles that reflect the signal). Various signals will appear out of phase with each other, thereby canceling each other out to a certain extent, reducing signal strength (called "fading" in this field). This kind of signal fading generally occurs in the spatial coverage area of ​​the system. Areas of fading can be very noticeable, potentially resulting in complete loss of signal. [0003] In addition, when the mobile station moves around in the wireless...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H03J7/02H04B1/16H04L27/00H04L27/227H04L27/233
CPCH04L2027/003H04L27/2332H04L2027/0034H04L2027/0046
Inventor R·拉梅斯
Owner TELEFON AB LM ERICSSON (PUBL)