Joint Transmission for Space Time Block Coded TD-SCDMA

Since time division synchronous code division multiple access (TD-SCDMA) technology, one of the time division duplex (TDD) standards modes of 3rd Generation Partnership Project (3GPP), adopted a lower spreading rate, 1.28 MChip/sec, it is usually referred to low chip rate time division CDMA (LCR-TD-CDMA). Therefore its multipath diversity is not large enough due to fewer independent paths. Furthermore, it suffers from multi-user access interference (MAI) as other CDMA systems, where the influence of MAI is not small due to its small spreading factor. Our proposed solution overcomes all these shortcomings of TD-SCDMA technology. We propose an implementation of space time block coding (STBC) to introduce diversity to combat low multi-path diversity character of TD-SCDMA. We further incorporate joint transmission (JT) technique to remove MAI, and thereby improve system performance. The introduction of JT at the base station (BS) side also helps to reduce the complexity of the mobile station (MS). We use a combination of analytical and simulation methods to evaluate the performance of the proposed system. The results show significant improvement for the proposed system