TY - JOUR
T1 - On the performance of multicarrier DS-CDMA with imperfect power control and variable spreading factors
AU - Wang, Li Chun
AU - Chang, Chih Wen
N1 - Funding Information:
Manuscript received April 1, 2005; revised October 1, 2005. This work was supported in part by the National Science Council and in part the Program of Promoting University Excellence of Ministry of Education, Taiwan under Contract 93-2219-E-009-012 and Contract EX-91-E-FA06-4-4. This paper was presented in part at the 2005 IEEE Global Telecommunications Conference, St. Louis, MI, November 28–December 2, 2005.
PY - 2006/6
Y1 - 2006/6
N2 - Multicarrier direct-sequence code-division multiple access (MC-DS-CDMA) becomes an attractive technique for the future fourth-generation (4G) wireless system because it can flexibly adapt transmission rates by changing both time and frequency spreading factors and possesses many physical-layer advantages in dispersive fading channels. However, power control errors (PCE) and the complete multiple access interference (MAI) from all the intersubcarriers may significantly degrade the performance of the MC-DS-CDMA system. In this paper, we propose an analytical method to evaluate the joint effects of the PCE and the complete MAI on the multirate MC-DS-CDMA system. From analysis and simulation, we obtain some important insights into the performance issues of the MC-DS-CDMA system. First, the effect of PCE can exacerbate the impact of the complete MAI on the MC-DS-CDMA system, or vice versa. For BER = 10 -3 in a considered case, the joint effect of the complete MAI and PCE further degrades the performance by 2.1 dB compared with the sum of the degradation from the complete MAI and the PCE individually. Second, increasing frequency- or time-domain spreading gain can improve the performance of the MC-DS-CDMA system, but the system also becomes more sensitive to power control errors. Third, a larger PCE can possibly make the frequency-domain diversity diminish faster than the gain obtained from the time-domain spreading although an MC-DS-CDMA system with a larger frequency-domain spreading gain (M) is usually better than that with a larger time-domain spreading gain (G o). In our example, for the standard deviation of PCE (σ e) equal to 0 dB, the BERs with(M, G o) = (4,16) and (16,4) are 9.3×10 -4 and 3.7×10 -5, respectively, while for σ e = 4 dB, the BER performances of the two cases are all in the order of 10 -3.
AB - Multicarrier direct-sequence code-division multiple access (MC-DS-CDMA) becomes an attractive technique for the future fourth-generation (4G) wireless system because it can flexibly adapt transmission rates by changing both time and frequency spreading factors and possesses many physical-layer advantages in dispersive fading channels. However, power control errors (PCE) and the complete multiple access interference (MAI) from all the intersubcarriers may significantly degrade the performance of the MC-DS-CDMA system. In this paper, we propose an analytical method to evaluate the joint effects of the PCE and the complete MAI on the multirate MC-DS-CDMA system. From analysis and simulation, we obtain some important insights into the performance issues of the MC-DS-CDMA system. First, the effect of PCE can exacerbate the impact of the complete MAI on the MC-DS-CDMA system, or vice versa. For BER = 10 -3 in a considered case, the joint effect of the complete MAI and PCE further degrades the performance by 2.1 dB compared with the sum of the degradation from the complete MAI and the PCE individually. Second, increasing frequency- or time-domain spreading gain can improve the performance of the MC-DS-CDMA system, but the system also becomes more sensitive to power control errors. Third, a larger PCE can possibly make the frequency-domain diversity diminish faster than the gain obtained from the time-domain spreading although an MC-DS-CDMA system with a larger frequency-domain spreading gain (M) is usually better than that with a larger time-domain spreading gain (G o). In our example, for the standard deviation of PCE (σ e) equal to 0 dB, the BERs with(M, G o) = (4,16) and (16,4) are 9.3×10 -4 and 3.7×10 -5, respectively, while for σ e = 4 dB, the BER performances of the two cases are all in the order of 10 -3.
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U2 - 10.1109/JSAC.2005.864025
DO - 10.1109/JSAC.2005.864025
M3 - Article
AN - SCOPUS:33746261363
SN - 0733-8716
VL - 24
SP - 1154
EP - 1165
JO - IEEE Journal on Selected Areas in Communications
JF - IEEE Journal on Selected Areas in Communications
IS - 6
ER -