The reverse link performance of coherent multicode DS-CDMA [4], [5] under multipath Rayleigh fading environments is evaluated by computer simulation. It is demonstrated that the combined use of pilot symbol assisted (PSA)-coherent RAKE, channel coding, antenna diversity, and transmit power control is powerful in lowering the required signal energy per information bit-to-interference plus additive white Gaussian nose (AWGN) power spectrum density ratio (Eb/Io) which is an important parameter in determining the link capacity. It is also demonstrated that with slight performance degradation, high rate data transmission is realized by using multiple orthogonal spreading codes in parallel (orthogonal multicode transmission). Based on the simulated link performance, the reverse link cell capacity and link budget are also evaluated. It is found that parameter η=Io/No plays an important role in controlling the cell capacity and the maximum allowable path loss, where No is the AWGN power spectrum density.

Direct sequence code division multiple access (DS-CDMA) is a promising candidate for 3rd generation mobile communications systems. We recently proposed a coherent multicode DS-CDMA (CM-CDMA) scheme that uses pilot symbol-aided coherent RAKE, interference power measurement based transmit power control, orthogonal multicode transmission, and concatenated channel coding. We have implemented a CM-CDMA test-bed for a series of laboratory and field tests using the 2 GHz band. This paper describes the test-bed system and experimental results are presented. It is confirmed that pilot symbol-aided coherent RAKE can reduce the required signal energy per bit-to-interference plus background noise spectrum density ratio (Eb/Io) by 2-3 dB from that achievable with differential detection. Also shown is that by using both RAKE combining and SIR-based power control the transmit power of mobile stations can be significantly reduced. Measurement results show that the required Eb/Io degrades only slightly when 24 code-channels (768 kbps) are used since orthogonal Gold sequences are used as short spreading codes.