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A self-adapted modulation and encoding method for orthogonal frequency division multiplexing system

An adaptive modulation and orthogonal frequency division technology, applied in the field of modulation and coding, can solve problems such as ineffectiveness, increase in bit error rate, waste of system capacity, etc., and achieve the effect of improving spectrum efficiency, reducing possibility, and enhancing effectiveness

Inactive Publication Date: 2011-08-10
ZTE CORP
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Problems solved by technology

But in fast time-varying environments, fixed time windows may make it difficult to track fast fading channels with a predefined update period
In other words, the update period is relatively large, and the current CQI may not be valid for the next transmission with actual feedback delay
[0007] In addition, the above method uses the average RSSI of the signal received within the time window to determine the modulation, demodulation and coding scheme (MCS, Modulation and Coding Schemes) corresponding to the changing channel, without considering the channel fluctuation
In fact, the fluctuation error of the received signal RSSI will lead to the selection of an inappropriate modulation scheme. As a result, the signal modulation and coding methods are improperly selected, which wastes the system capacity or causes an increase in the bit error rate.

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  • A self-adapted modulation and encoding method for orthogonal frequency division multiplexing system
  • A self-adapted modulation and encoding method for orthogonal frequency division multiplexing system
  • A self-adapted modulation and encoding method for orthogonal frequency division multiplexing system

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Embodiment Construction

[0036] figure 1 It is a flowchart of the adaptive modulation and coding method described in the present invention, comprising the following steps:

[0037] Step 110, set an initial time window parameter k=1, usually choose the one with the largest window length as the initial time window.

[0038] Step 120, get the adaptive time window W according to the time window parameter k k , k ∈ 1, 2, ..., K.

[0039] time window W k , k=1, 2,..., K respectively correspond to different terminal moving speed v of the terminal k , k=1, 2,..., K, can be determined by estimating the channel coherence time, the coherence time t k =λ·v c / (v k f), k=1, 2, . . . , K. where λ is the empirical coefficient, v c is the speed of light, v k is the mobile speed of the terminal, and f is the carrier frequency.

[0040] When the carrier frequency is 3.5MHz and the mobile speed of the terminal is 3km / h, 30km / h, 60km / h, 120km / h, the corresponding channel coherence times are 43.51ms, 4.35ms, 2.1...

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Abstract

The invention discloses a self-adapting modulating and coding method in orthogonal frequency division multiplexing system, it includes: the first step, setting original time window; the second step, obtaining adapted time window based on time window parameter; the third step, based station evaluates average RSSI value and standard difference of down sending time window; the forth step, inquiring AMC judging graph to obtain corresponding modulating and coding mode based on average RSSI value and standard difference; the fifth step, evaluating error code ratio, and comparing with expected errorcode ratio: if evaluated error code ratio <= expected error code ratio, turn to step six; If else, adjust time window parameter, turn to step two; the sixth step, modulate and code. The invention canobtain modulating and coding mode which fits for current channel, increases actual effect of AMC, decreases possibility of interrupt of system, increases spectrum efficiency, at the same time error ratio can be decreased.

Description

technical field [0001] The present invention relates to modulation and coding technology in wireless communication, in particular to adaptive modulation and coding method in Orthogonal Frequency Division Multiplexing (OFDM, Orthogonal Frequency Division Multiplexing) system. Background technique [0002] In reality, the wireless channel has time-varying and fading characteristics. When there is no system error or bit error constraint, the wireless channel capacity is also a time-varying random variable. To maximize the use of channel capacity, only the transmission rate is also a random variable. The amount of channel capacity change, that is, to make the coding and modulation methods adaptive. Adaptive tracking for the time-varying characteristics of the physical channel will bring great benefits to the improvement of system performance. Link adaptive technology can have many methods, such as power control, adaptive modulation and coding (AMC, Adaptive Modulation and Coding...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H04L27/26H04L1/00
Inventor 王衍文蒋小奎张力
Owner ZTE CORP
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