Title :
Comparison of coherent and noncoherent CDMA system in time varying fading channel
Author :
Kim, Ki Jun ; Kwon, Soon Yil ; Hwang, Seung Hoon ; Pak, Chae Ha ; Whang, Keum Chan
Author_Institution :
Dept. of Electr. Eng., Yonsei Univ., Seoul, South Korea
Abstract :
The direct-sequence code-division multiple access (DS-CDMA) system has received much attention for digital mobile cellular telephone and personal communication network (PCN) applications. The performance of a coherent CDMA system is compared with that of a noncoherent CDMA system according to the extent of the channel variation and offset frequency. A pilot signal is used for coherent detection. Using a RAKE receiver, we evaluate the BER of the uncoded system analytically considering the estimation error of the carrier phase. Also the power ratio of the pilot signal to the data signal and the integration length of the channel estimator of the coherent BPSK system is optimized according to the fading bandwidth and offset frequency. The required SIR of the BPSK system is compared with that of a DPSK system. Additionally we determine the extent of performance improvement which can be achieved by convolutional coding. The results show that the optimum performance of BPSK is at least 1 dB better in terms of the required SIR than that of DPSK in practical ranges
Keywords :
code division multiple access; coding errors; digital radio; error analysis; error statistics; fading; land mobile radio; phase estimation; phase shift keying; pseudonoise codes; radio receivers; radiofrequency interference; signal detection; spread spectrum communication; time-varying channels; BER; DPSK system; DS-SS; PCN; RAKE receiver; SIR; carrier phase; channel estimator; channel variation; coherent BPSK system; coherent CDMA system; coherent detection; convolutional coding; data signal; digital mobile radio; estimation error; fading bandwidth; integration length; noncoherent CDMA system; offset frequency; performance comparison; pilot signal; power ratio; time varying fading channel; uncoded system; Binary phase shift keying; Cellular networks; Differential quadrature phase shift keying; Direct-sequence code-division multiple access; Fading; Frequency estimation; Multiaccess communication; Personal communication networks; Telephony; Time varying systems;
Conference_Titel :
Vehicular Technology Conference, 1996. Mobile Technology for the Human Race., IEEE 46th
Conference_Location :
Atlanta, GA
Print_ISBN :
0-7803-3157-5
DOI :
10.1109/VETEC.1996.501438
