Search

A suboptimum search algorithm that considers the users' power profile in conjunction with a primary stage of polynomial-expanded (PE) linear multiuser detector for mobile uplink is proposed to suppress interference level. The initial stage is improved by mathematical analysis using two new ideas based on the Rayleigh-Ritz and Gershgorin theorems for both synchronous and asynchronous users. The performance of the PE structure is further enhanced by a new suboptimum search algorithm as the second stage. The structure of the search algorithm is based on starting from a point close to the optimum search and performing sequential steps to modify it. The proposed structures of the PE method and the suboptimum search algorithm are well suited together and make them collaboratively work without encountering a high level of complexity, since they use similar information as the correlation matrix. The power profile of the users is also considered in the suboptimum search algorithm, which led to more than a 50% reduction of the complexity, while keeping the performance almost the same. The performance of the final structure is carried out by means of computer simulations, and it has been compared to a partial parallel interference cancellation method with optimized partial coefficients. One of the main features of the structure proposed in this paper is that it performs its operations on the canonical formulation of the system, which makes it highly suitable for a broad range of systems such as multicarrier code division multiple access and multiinput multioutput.

A suboptimum search algorithm to suppress the interference level in conjunction with a primary stage of iterative linear multiuser detector for the mobile uplink is proposed. The initial stage is improved through analytical analysis. The structure of the iterative method and the suboptimum search algorithm are well suited together and makes them collaboratively work without encountering a high level of complexity. Considering the power profile of the users in the suboptimum search algorithm leaded to even less complexity, yet keeping the performance almost the same. The performance of the structure is obtained by simulations and has been compared to parallel interference cancellation method.

Partial parallel interference cancellation (PPIC) for CDMA mobile communication is known as a powerful method. In this paper, after a brief look at PPIC, a multisensor version of the approach is studied under the UMTS uplink parameters. The performance is evaluated by considering a multipath fading environment and the effect of channel estimation in the receiver. The results are compared with standard RAKE receiver and the differences show a promising gain.