MAP Code Acquisition Shows Superiority of Bologna Codes in a Class of Multiuser CDMA Systems
نویسندگان
چکیده
A maximum a posteriori probability (MAP) code acquisition scheme is proposed which utilizes all the available information by exploiting stochastic properties of spreading codes. Application of this method shows: i) code acquistion superiority of Bologna codes (Markov codes having eigenvalue of the transition probability matrix λ = √ 3 − 2) over independent and identically distributed (i.i.d.) codes in chip-asynchronous multiuser systems, when acquisition time is fixed and ii) comparsion of Markov codes with different values of λ shows that code acquisition performance is best for Bologna codes.
منابع مشابه
Nonlinear Multiuser Receiver for Optimized Chaos-Based DS-CDMA Systems
Chaos based communications have drawn increasing attention over the past years. Chaotic signals are derived from non-linear dynamic systems. They are aperiodic, broadband and deterministic signals that appear random in the time domain. Because of these properties, chaotic signals have been proposed to generate spreading sequences for wide-band secure communication recently. Like conventional DS...
متن کاملBlind Multiuser Detection Based on Subspace Estimation
In this paper, we study an enhanced subspace based approach for the mitigation of multiple access interference (MAI) in direct-sequence code-division multiple-access (DS-CDMA) systems over frequencyselective channels. Blind multiuser detection based on signal subspace estimation is of special interest in mitigating MAI in CDMA systems since it is impractical to assume perfect knowledge of param...
متن کاملAn Iterative Multiuser Detector for DS-CDMA
We propose an iterative multiuser detector for Turbo coded Direct Sequence CDMA (DS-CDMA) systems. The receiver is derived from the Maximum a-Posteriori (MAP) estimation of the single user’s transmitted data, conditioned on information about the estimate of the Multiple Access Interference (MAI) and the received signal from the channel. The complexity of the proposed receiver increases linearly...
متن کاملCode acquisition in coherent optical pulse CDMA systems utilizing coherent correlation demodulation
A code acquisition technique based on active optical correlation detection is introduced for coherent optical pulse code-division multiple-access (CDMA) systems implemented through coherent correlation demodulation. Passive matched filter acquisition, commonplace in most radio CDMA systems, does not translate directly into the optical domain since synchronization between the incoming optical si...
متن کاملNear-far Resistant Code Synchronization for Cdma Systems | an Implementation Perspective
|In this paper we evaluate and compare several algorithms based on eigenanalysis techniques for near-far resistant code acquisition and tracking, i.e., delay estimation in multiuser CDMA communication systems under di erent operating conditions. We show how the algorithms derived for the static case can easily be adapted to cope with time-varying situations. The proposed schemes are applicable ...
متن کامل