Outer loop control of fast transmit power control based on intermediate block error rate in concatenated channel coding for DS-CDMA mobile radio

This paper proposes an outer loop control method of fast transmit power control (TPC) for high-quality data transmission such as that with the average bit error rate (BER) of 10^-6 in serial concatenated channel coding combining convolutional (inner) and Reed-Solomon (outer) codings for DS-CDMA mobile radio. In the proposed method, the outer loop control is performed based on the measured intermediate block error rate (BLER) value after inner-channel decoding. Since the number of block errors after inner-channel decoding is much greater than that of the final output after outer channel decoding, fast tracking performance of the sudden changes in the propagation conditions such as the number of multipaths and fading Doppler frequency, i.e., moving speed of the mobile station, is achieved. The experimental results clarify that the measured BLER after outer channel decoding is accurately controlled to almost a constant value from the low to high fading maximum Doppler frequency of up to 480 Hz, and that the measured BER after outer channel decoding is within the range of one-order of magnitude of the antenna diversity reception (meanwhile, the target SIR value after Rake combining varied with the range of 2.5 dB).