14 *5.5.3. Effect of MAI*

15 To show the effect of MAI, Fig.14 depicts the BER performance of the DS-CDMA downlink 16 wireless communication system employing the GR with the unified complex Hadamard 17 transform spreading sequences and WH spreading sequences as a function of the number of 18 active users *K*. The BER performance of the DS-CDMA downlink wireless communication 19 system employing the GR with the unified complex Hadamard transform spreading 20 sequences is better than that of the DS-CDMA downlink wireless communication system 21 employing the GR with the WH spreading sequences at the high SNR and all the chosen 22 values of *K*. Although the advantage brought by using the unified complex Hadamard 23 transform spreading sequences in the DS-CDMA downlink wireless communication system 24 employing the GR fades gradually with the increase of MAI. For example, under the large 25 number of users and small SNR, the BER performance of the DS-CDMA downlink wireless 26 communication system employing the GR with the unified complex Hadamard transform 27 spreading sequences is comparable to that of the DS-CDMA downlink wireless 28 communication system employing the GR with the WH spreading sequences in the low 29 SNR region. Also, for all cases, a great superiority of the GR implementation in the DS-30 CDMA downlink wireless communication system with the unified complex Hadamard 31 transform spreading sequences and WH spreading sequences in comparison with 32 employment of the Rake receiver in the same system is evident. These results in simulations 33 have verified our theoretical analysis.
