Design and analysis of receiver filters for multiple chip-rate DS-CDMA systems

As multimedia applications proliferate, there is a desire to provide wirele ss transport to information streams with inherently different data rates. D irect-sequence code division multiple access (DS-CDMA) is a natural multipl e-access strategy for multiple data-rate systems. Recent work on multirate DS-CDMA receivers has focused on signal-processing techniques, which detect all users of all rates simultaneously. In the current work, multirate user s have multiple bandwidths. Thus, it is proposed to exploit bandwidth diffe rences to achieve frequency-based rate separation followed by single-rate d etection schemes. Such a methodology enables a tradeoff between receiver co mplexity and performance. The performance of the proposed filters and recei vers are derived for both a modified matched filter and modified decorrelat or employing rate separation, Performance of a multirate CDMA overlay syste m is evaluated. In addition, chip pulse shaping for wide-band users is deve loped to improve performance for narrow-band users for the overlay system.