A feedback information transmission method of adaptive OFDM system

A technology of orthogonal frequency division and feedback information, applied in the field of adaptive orthogonal frequency division multiplexing system, can solve the problems of wasting system resources and increasing signaling overhead, so as to improve system efficiency, reduce overhead, and reduce uplink The effect of road interference

Inactive Publication Date: 2005-01-19
ALCATEL LUCENT SHANGHAI BELL CO LTD
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Problems solved by technology

If the received CQI does not change or does not change much, then the modulation and coding scheme of the access point (AP) will not

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  • A feedback information transmission method of adaptive OFDM system
  • A feedback information transmission method of adaptive OFDM system
  • A feedback information transmission method of adaptive OFDM system

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Embodiment Construction

[0020] In the link adaptive technology of the OFDM system, we can define the link adaptive technology as three levels. The highest level is DRA, which can improve the throughput of the entire system, that is, increase the amount of information correctly received per unit time; the second level is AMC, which can achieve the target BER and save consumption when the channel quality changes Power; the third level is the lowest level HARQ, which can improve BER by retransmitting source data. When AMC, HARQ and DRA are combined in an adaptive OFDM system, the relationship between the time used by a process of each technology is as follows:

[0021] T dra ≥T amc ≥T harq

[0022] In an adaptive OFDM system, one of the main functions of DRA is to allocate appropriate time-frequency units (TFU) to different users, and AMC is responsible for selecting an appropriate MCS according to the predicted channel quality. Suppose the time taken by a DRA process is T dra , the time taken by ...

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Abstract

The invention provides a feedback information transmitting method in self-adapting orthogonal frequency division multiplex (OFDM system, combining self-adapting modulating and coding (MAC) technique with hybrid auto-retransfer request (HARQ) technique and including the following steps: a. a mobile terminal receives data transmitted by access point, then transmits a confirm/nonconfirm (ACK/NACK) information to the access point and simultaneously measures channel quality and obtains channel quality indication (CQI); b. the mobile terminal judges if the measured CQI in a period of time is good a CQI: if it is, transmit the CQI to the access point and otherwise do not transmit the CQI. It can reduce the overhead of feedback signalling, thus reducing the ascending link interference in the self-adapting OFDM system and increasing the system efficiency.

Description

technical field [0001] The invention relates to an adaptive orthogonal frequency division multiplexing (OFDM) system, in particular to a feedback information transmission method in the adaptive OFDM system. Background technique [0002] Using Adaptive Modulation and Coding (AMC) in OFDM system, Channel Quality Indicator (CQI) needs to be fed back to the sender to select the appropriate Modulation and Coding Scheme (MCS). In advanced OFDM systems, there are link adaptation techniques such as adaptive modulation and coding (AMC), hybrid automatic repeat transmission (HARQ) and dynamic resource allocation (DRA). [0003] It should be noted that in a fast fading environment, AMC cannot work effectively in a fast fading environment because the coherence time caused by the high-speed movement of the mobile station is small. And HARQ is not very sensitive to the channel estimation error. Therefore, in a link adaptive system, AMC is usually combined with...

Claims

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Application Information

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IPC IPC(8): H04L1/18H04B7/26H04J1/00H04J11/00H04L1/00H04L1/12H04L27/26
Inventor 宋鹏鹏黎光洁李栋
Owner ALCATEL LUCENT SHANGHAI BELL CO LTD
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