Method and device for adaptive modulation and coding based on second order statistics of channel information
First Claim
1. A method for adaptive modulation and coding based on second order statistics of channel information in orthogonal frequency divisional multiplexing (OFDM) systems, said method comprises following steps:
- a) a mobile station determining the largest among a set of adaptation time windows T1, T2, . . . Tn as a current adaptation time window;
b) said mobile station receiving a set of pilot signals from a base station in the current adaptation time window, obtaining Signal-to-Noise ratio (SNR) samples based on the set of pilot signals, calculating variance β
of the SNR and average value γ
of the SNR;
c) comparing said variance β
of SNR in step b) with threshold values β
0, β
k, obtaining a final current adaptation time window and a current modulation and coding scheme according to the results from comparison and said average value γ
of SNR;
d) feeding the final current adaptation time window and the current modulation and coding scheme, which are obtained in step c), back to the base station as parameters for the base station to transmit data next time.
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Abstract
The present invention discloses a method and device for adaptive modulation and coding based on second order statistics of channel information in OFDM system, characterized in that, by means of variance of Signal-to-Noise ratio (SNR) an appropriate adaptation time window is selected dynamically to trace time-varying channel better; and in that a decision criterion of second order, namely selecting an appropriate modulation and coding schemes (MCS) according to average value of SNR and variance of SNR, is employed to obtain accurate mapping from SNR to MCS. The mapping enhances practicability of the adaptive modulation and coding, decreases probability of system outage, and thus results in better performance of bit error rate.
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Citations
10 Claims
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1. A method for adaptive modulation and coding based on second order statistics of channel information in orthogonal frequency divisional multiplexing (OFDM) systems, said method comprises following steps:
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a) a mobile station determining the largest among a set of adaptation time windows T1, T2, . . . Tn as a current adaptation time window; b) said mobile station receiving a set of pilot signals from a base station in the current adaptation time window, obtaining Signal-to-Noise ratio (SNR) samples based on the set of pilot signals, calculating variance β
of the SNR and average value γ
of the SNR;c) comparing said variance β
of SNR in step b) with threshold values β
0, β
k, obtaining a final current adaptation time window and a current modulation and coding scheme according to the results from comparison and said average value γ
of SNR;d) feeding the final current adaptation time window and the current modulation and coding scheme, which are obtained in step c), back to the base station as parameters for the base station to transmit data next time. - View Dependent Claims (2, 3, 4, 5)
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6. A device for adaptive modulation and coding based on second order statistics of channel information in orthogonal frequency divisional multiplexing (OFDM) systems, said device comprising calculation means and comparison-update means which are located in a mobile station, wherein:
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a channel estimation means of the mobile station for obtaining a sample of Signal-to-Noise Ratio (SNR) in accordance with pilot signals received from a base station by the mobile station, wherein current adaptation time window is the largest among a set of adaptation time windows T1, T2, . . . Tn; the calculation means for calculating variance of the SNR β and
average value of the SNR γ
in accordance with the SNR samples obtained by said channel estimation means; andthe comparison-update means for comparing the calculated variance β
of the SNR with threshold values β
0, β
k, then obtaining a final current adaptation time window and a current modulation and coding scheme according to results from comparison and the average value of SNR γ
obtained from the calculation means, said final current adaptation time window and the current modulation and coding scheme is fed back to said base station as parameters for said base station to transmit data next time. - View Dependent Claims (7, 8, 9, 10)
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Specification