Oversaturated group orthogonal CDMA (GO-CDMA) offers an elegant way of increasing capacity of synchronous DS-CDMA, which allows existence of number of users exceeding signal space dimension. The system provides excellent results in synchronous single-path channels; however, in multipath channels complicated equalizers of big length are required to secure good performance due to significant MAI. In this paper implementation of chip interleaving with zero padding in GO-CDMA system is considered to alleviate the effect of MAI. It is shown that this approach results in bit-synchronous multipath signals at the receiving end. Computer simulations demonstrate that in such a system the usage of the simplest zero-forcing equalizer of moderate length provides performance very close to that of GO-CDMA in an AWGN channel.

For original paper see Korn et al. (IEEE Trans. Commun., vol.51, no.9, p.1435-8, 2003 September). A more general and straightforward solution is given to the problem analyzed earlier in Korn of optimal energy distribution between two nonequiprobable signals detected coherently. The energy gain due to optimal energy allocation is shown to be independent of required bit-error probability

DVB-H is a new broadcasting standard, which offers reliable high data rate reception for mobile handheld and battery-powered devices. A link layer, including Reed-Solomon error correction combined with cyclic redundancy check (CRC), is defined in the standard to work on top of the DVB-T physical layer. The DVB-H suggests to use an erasure decoding method based on CRC information. Yet, the decoding method is not strictly determined in the standard. This paper investigates the performance of four different Reed-Solomon erasure decoding schemes for DVB-H link layer forward error correction

The method of increasing capacity of synchronous CDMA, called group orthogonal CDMA, is analyzed. When the number of users exceeds the signal space dimension the system becomes oversaturated. Previously designed oversaturated CDMA signatures are compared to conventional orthogonal signaling in multipath channel by computer simulations. Countermeasure to combat fading is to utilize zero forcing equalizer in the receiver. Results show that the energy loss due to larger number of active interferers in oversaturated system is for fading channels of the same order as for non-fading AWGN channel

Users' asynchronism and multipath propagation are among the most problematic issues in designing direct sequence code division multiple access (DS CDMA) systems. In this paper a system employing interleaved multiple signatures per user to mitigate the damaging effects of these factors is described and studied. It is demonstrated that interleaving along with an appropriate selection of users' signature multitudes drastically lowers the level of data-modulation-related peaks of multiple access interference

Oversaturated synchronous CDMA system is proposed based on collaborative coding, where data bits of group of L + s users are jointly one-to-one mapped onto 2/sup L+s/ L-dimensional signal vectors. Instead of the unique signature per each user, the L-dimensional signature subspace is used to transmit bits of L + s users (s > 0). All signature subspaces are orthogonal to each other which simplifies the optimal receiver structure. With signal space dimension N, the number of users is K = N(1 + s/L). Preferable collaborative codes are found using the sphere packing theory for L = 2...5, s = 1, 2. Trade-off between oversaturation efficiency and energy loss/gain is evaluated against the conventional non-oversaturated orthogonal CDMA.