A new block interleaver and noniterative decision feedback decoding enhance performance of IS-95 CDMA uplink or similar M-ary system

This paper investigates the combination of a new block interleaver design and a noniterative decision feedback receiver/decoder for IS-95 code-division multiple-access (CDMA) uplink in additive white Gaussian noise and a Rayleigh fading multipath environment. The new interleaver design yields better performance than the currently used IS-95 interleaver, with E_b/N₀ improvements of 0.27 to 0.76 dB. At the same time, the new interleaver design improves the effectiveness of a noniterative decision feedback receiver/decoder herein presented. The performance of the proposed design is measured via computer simulation for both coherent and noncoherent detection. A mathematical justification is also given to show the reason why the performance is improved using the proposed design. Based on these results, it is concluded that the use of the new interleaver design with noniterative decision feedback decoding can improve the quality of service and/or capacity of a modified cellular IS-95 system or a system using a similar concatenation of convolutional coding, interleaving, and orthogonal Walsh modulation. Although the approach presented is applied to the uplink of IS-95, it can also be applied to similar M-ary systems