Performance Analysis of Direct-Sequence Code-Division Multiple-Access Communications with Asymmetric Quadrature Phase-Shift-Keying Modulation
نویسندگان
چکیده
This article considers a quaternary direct-sequence code-division multiple-access (DS-CDMA) communication system with asymmetric quadrature phase-shiftkeying (AQPSK) modulation for unequal error protection (UEP) capability. Both time synchronous and asynchronous cases are investigated. An expression for the probability distribution of the multiple-access interference is derived. The exact bit-error performance and the approximate performance using a Gaussian approximation and random signature sequences are evaluated by extending the techniques used for uniform quadrature phase-shift-keying (QPSK) and binary phase-shiftkeying (BPSK) DS-CDMA systems. Finally, a general system model with unequal user power and the near–far problem is considered and analyzed. The results show that, for a system with UEP capability, the less protected data bits are more sensitive to the near–far effect that occurs in a multiple-access environment than are the more protected bits.
منابع مشابه
BER Analysis of Wideband Code Division Multiple Access
There has been a dramatic change in the field of field of telelcommunication service. M-ary Quadrature Amplitude modulation and Quadrature Phase shift Keying (QPSK) modulation schemes are considered in Wideband code Division Multiple Access(WCDMA) system. Here we are using MATLAB for simulation and evaluation of BER ( Bit Error Rate )and SNR(Siganl to Noise Ratio). There is analysis of Quadratu...
متن کاملBit Error Rate Performance Analysis on Modulation Techniques of Wideband Code Division Multiple Access
In the beginning of 21 st century there has been a dramatic shift in the market dynamics of telecommunication services. The transmission from base station to mobile or downlink transmission using M-ary Quadrature Amplitude modulation (QAM) and Quadrature phase shift keying (QPSK) modulation schemes are considered in Wideband-Code Division Multiple Access (W-CDMA) system. We have done the perfor...
متن کاملDirect sequence spread spectrum Walsh-QPSK modulation
In this paper we present Walsh-quadrature phase-shift keying (Walsh-QPSK) pseudonoise (PN) modulation schemes for both coherent and noncoherent direct-sequence code-division multiple-access (DS-CDMA) systems, wherein the PN spreading sequences for in-phase and quadrature data in a conventional QPSK PN modulation scheme are coded by Walsh sequences indexed by a special rule to reduce the envelop...
متن کاملOn the Performance of Energy-Division Multiple Access with Regular Constellations
In this paper we describe a multiple-access protocol in which different users are assumed to share the same bandwidth and the same pulse. Users employ the same modulation (binary-phase shift keying, quadrature-phase shift keying, and rectangular-phase shift keying are considered) with different transmitted magnitude, and are discriminated on the basis of the corresponding magnitude at receiver ...
متن کاملInnovative chip waveforms in microcellular DS/CDMA packet mobile radio
The impact of innovative chip waveforms on the performance of a direct sequence code-division multiple-access (DSICDMA) packet mobile radio network is investigated, assuming either Rayleigh or Nakagami-m frequency selective channels and a differential phase shift keying (DPSK) receiver with selection diversity. A constant improvement of the bit-error rate (BER) and the throughput is presented t...
متن کامل