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Method for transmitting empty hour code for orthogonal frequency division multiplexing system

An orthogonal frequency division and space-time code technology, applied in the field of transmitting space-time codes in OFDM systems, can solve problems such as long transmission period process, high terminal moving speed, and loss of receiving performance, so as to reduce impact, reduce transmission period, The effect of avoiding performance loss

Inactive Publication Date: 2006-10-25
HUAWEI TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in actual situations, the channel may change rapidly within four OFDM symbol time, and at this time, it can be considered that the mobile speed of the terminal is very high, which will lead to a decline in receiving performance
Therefore, the transmission cycle process in the prior art is too long, resulting in a great loss of reception performance due to the change of the channel fading coefficient
[0013] Although the disadvantages of the prior art have been described specifically by taking three antennas as an example, the disadvantages still exist for the OFDM system with four antennas.
Moreover, OFDM systems with more than four antennas still suffer from this disadvantage

Method used

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  • Method for transmitting empty hour code for orthogonal frequency division multiplexing system
  • Method for transmitting empty hour code for orthogonal frequency division multiplexing system
  • Method for transmitting empty hour code for orthogonal frequency division multiplexing system

Examples

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no. 1 example

[0050] In the first embodiment, the case where there are three transmitting antennas and STBC is used for space-time coding is described.

[0051] according to image 3 In the process shown, first, the information bits output by the source are modulated to obtain modulation symbols, and STBC space-time coding is performed on the modulation symbols to obtain encoded codewords; then the codewords are mapped to at least two subcarriers of OFDM symbols , and the codeword is transmitted on the transmit antenna. In STBC space-time coding with three antennas, each coding operation takes three modulation symbols x 1 , x 2 and x 3 , x i * is x i The complex conjugate of , i=1,2,3.

[0052] Table 2 is a schematic diagram of the first mapping mode of the three-antenna space-time block coding in the OFDM system according to the first embodiment of the present invention. Wherein, the codewords on each antenna after space-time encoding are respectively mapped to two subcarriers of t...

no. 2 example

[0062] The second embodiment of the present invention will be described below by using four transmitting antennas and using STBC for space-time coding.

[0063] according to image 3 In the flow shown, first, the information bits output by the information source are modulated to obtain modulation symbols, and space-time coding is performed on the modulation symbols to obtain encoded codewords; then the codewords are mapped to at least two subcarriers of OFDM symbols, And the codeword is transmitted on the transmit antenna. In STBC space-time coding with four antennas, each coding operation takes three modulation symbols x 1 , x 2 and x 3 . x i * is x i The complex conjugate of , i=1,2,3.

[0064] Table 4 is a schematic diagram of the first mapping mode of the four-antenna space-time block coding in the OFDM system according to the second embodiment of the present invention. Wherein, the codewords on each antenna after space-time encoding are respectively mapped to two...

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Abstract

The system includes n pieces of transmitting antenna, where n is a positive integer at least as 3. The method includes steps: modulating information bits output from information source so as to obtain modulation symbol; carrying out time space coding for modulation symbol to obtain coded code word; mapping code word to at least two sub carrier waves of symbols in orthogonal frequency division multiplex (OFDM); then transmitting code words through n pieces of transmitting antenna. Tranmitting operation of time space codes through time and sub carrier wave, the invention reduces transmit cycle needed for transmitting time space codes, and lowers influence on sending time space code caused by correlation time of channel. The invention prevents performance loss of transmitting time space codes caused by change of channel fading coefficient in one time for operating time space codes.

Description

technical field [0001] The invention belongs to the technical field of Orthogonal Frequency Division Multiplexing (OFDM), more precisely, relates to a method for transmitting a space-time code in an OFDM system. Background technique [0002] At present, with the development of mobile communication systems, mobile communication services have expanded from pure voice services to multimedia services. These services usually need to transmit a large amount of data, so the mobile communication system requires a higher bit transmission rate. In a conventional single-carrier system, if a higher bit transmission rate is used, it will bring difficulties to the effective reception of the signal due to inter-symbol interference (ISI) and deep frequency selective fading of the wireless channel. [0003] Because it can well overcome the multipath characteristics of wireless channels and can perform frequency domain scheduling, OFDM technology has become a recent research hotspot. OFDM t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H04L27/26H04L1/06
Inventor 陈莉娜蒋培刚
Owner HUAWEI TECH CO LTD