Reconfiguration Aspects and a Reconfigurable Outer Block Interleaver for 3G Applications

Abstract

Reconfiguration concept represents reconfigurable functionalities of the radio interface for mobile radio systems. Particularly for the physical layer, some possible reconfigurable architectures can be identified. We focus on outer interleaving for turbo codes, which can improve their performance in flat Rayleigh fading environment. The larger the number of columns in the outer interleaver, the better is the performance, but with the penalty of more complexity and delay. Furthermore, an incorrect choice of the number of columns can increase the bit and frame error rates. Therefore, it would be advantageous to reconfigure the outer interleaver in different operating environments with the optimum number of columns. Using two different data frame lengths, in this contribution simulation results are presented for the four possible outer block interleaver configurations specified for the 3GPP mobile standard in the case of flat Rayleigh fading channel. It is shown that different operating environments require an optimum number of columns in terms of bit error rate and frame error rate performance. Finally, frame fade duration is considered and the effect of the product of the Doppler frequency with the frame duration on the performance for the four different 3GPP outer block interleaver configurations is discussed.

Implementation of an improved reconfigurable SOVA/log-MAP turbo decoder in LTE

“…To scale the extrinsic information in the turbo decoder a common factor s=0.7 is used in both algorithms, according to [4]. In order to compute the latency t d for our system, a pipeline architecture is assumed for the turbo decoder.…”

“…We also assume a single transmitting and receiving antenna in our system. The formulas to calculate the latency for the two algorithms are the same as in [4]. Table 1 presents the two implementation scenarios of the reconfigurable SOVA/log-MAP turbo decoder.…”

Novel Results on 3G Reconfigurable Outer Block Interleaving Based on FER

“…It is also mentioned that the bit error rate (BER) will be higher unless the right number of columns is employed. In [12,13] we discussed different UMTS turbo codes implementation scenarios for an outer block interleaver, different frame lengths, operating environments and a constant data rate. In [14] we followed the same approach but constant frame length and different data rates.…”

UMTS Dynamic Outer Interleaver Reconfiguration for Indoor Environment Using SOVA Turbo Decoder

“…The first reconfiguration type involves common functionalities of the radio transceiver between different mobile standards operating worldwide in order to achieve interoperability in a single mobile terminal. The second type deals with reconfiguration within a single mobile standard, which represents the adjustment of the parameters of a radio transceiver according to the specific operating conditions and the required performance and complexity [4,5].…”