Mustafa Karakoc

Design and Hardware Implementation of a Novel Smart Antenna Algorithm Using TI DSPs

This paper presents design and implementation of a novel smart antenna algorithm referred as space code correlator (SCC). The algorithm is based on storing predetermined array response vectors, and performing code correlation with the desired users code and then spatial correlation of despread signal with stored array response vectors. The design methodology aims to find a beamforming weight vector that provides satisfactory SINR performance with fixed execution time so that convergence problem is avoided. SCC algorithm is implemented on the different Texas Instruments (TI) TMS320C67x floating-point digital signal processors (DSP) taking into account multipath propagation conditions. The implementation steps and results pertaining weight vector estimation time and SINR performance are presented. Results show that with careful selection of DOA search window and multipath SNR level, the SCC algorithm provides implementation time less than 10 ms frame interval of cdma2000 system

Software radio implementation of a smart antenna system on digital signal processors for cdma2000

This paper presents a software defined radio (SDR) implementation based on programmable digital signal processors (DSP) for smart antenna systems (SAS). We evaluate adaptive beamforming algorithms, namely non-blind-type least mean square (LMS) and blind-type constant modulus (CM) using TI TMS320C6000 high performance DSPs for cdma2000 reverse link. Adaptive beamformers are implemented using TI code composer studio (CCS) that includes assembly language and C code development tools. Performance variation of these sofware radio beamformers in terms of weight computation time and received SINR are compared for different C6000 development boards (TMS320C6701 EVM, TMS320C6711 DSK, and TMS320C6713 DSK) and array topologies under varying multipath propagation conditions. Results show that while antenna array and algorithm type are important for the SINR performance, DSP type becomes important for the weight computation time.

Evaluation of Smart Antenna Algorithms for cdma2000 Reverse Link

Adaptive algorithms which provide desired performance and have small computational load are key factors that enable the integration of smart antennas into 3G wireless communication systems. We evaluate non-blind (LMS, RLS), blind (CM), and semi-blind (CFA) type receive beamforming algorithms in terms of their performance, complexity, and convergence rate for cdma2000 systems. Simulations are performed for a 5-element uniform linear array operating in a wireless vector channel that consists of multipaths and multiple access interference. Results show that CFA has the highest SINR with minimum deviation in varying fading conditions. CM has the smallest SINR performance possibly due to not involving pilot information, but it has the computation load as low as LMS does, i.e. O(M) where M is the antenna number. RLS achieves SINR comparable to CFA with the fastest convergence rate.

Stochastic methods for dynamic OVSF code assignment in 3G networks

Orthogonal variable spreading factor (OVSF) codes are widely used to provide variable data rates for supporting different bandwidth requirements in wideband code division multiple access (WCDMA) systems. Many works in the literature have intensively investigated to find an optimal dynamic code assignment scheme for OVSF codes. Unlike earlier studies, which assign OVSF codes using conventional (CCA) or dynamic (DCA) code allocation schemes, in this paper, stochastic optimization methods which are genetic algorithm (GA) and simulated annealing (SA) were applied which population is adaptively constructed according to existing traffic density in the OVSF code-tree. Also, the influences of the GA (selection, crossover and mutation techniques) and the SA (cooling schedules, number of inner loop) parameters were examined on the dynamic OVSF code allocation problem. Simulation results show that the GA and SA provide reduced code blocking probability and improved spectral efficiency when compared to the CCA and DCA schemes.

Genetic Algorithm and Simulated Annealing for Dynamic OVSF Code Allocation in WCDMA Networks

Orthogonal variable spreading factor (OVSF) codes are used to provide variable data rates for supporting different bandwidth requirements in wideband code division multiple access (WCDMA) systems. Unlike existent studies such as assign OVSF codes using conventional (CCA) or dynamic (DCA) code allocation algorithms, in this paper, genetic algorithm (GA) and simulated annealing (SA) algorithms were applied which population size is adaptively constructed according to existing traffic density in the OVSF code-tree. The simulation results show that the GA and SA provide reduced code blocking probability and improved spectral efficiency in the system when compared to the CCA and DCA schemes. Finally, the more system performance results the more computational load.

A New Dynamic OVSF Code Allocation Method based on Adaptive Simulated Annealing Genetic Algorithm (ASAGA)

Orthogonal variable spreading factor (OVSF) codes are widely used to provide variable data rates for supporting different bandwidth requirements in wideband code division multiple access (WCDMA) systems. Many works in the literature have intensively investigated to find an optimal dynamic code assignment scheme for OVSF codes. Unlike earlier studies, which assign OVSF codes using conventional (CCA) or dynamic (DCA) code allocation schemes, in this paper, adaptive simulated annealing genetic algorithm (ASAGA) was applied which population is adaptively constructed according to existing traffic density in the OVSF code-tree. Also, the influences of the ASAGA parameters (selection, crossover and mutation techniques and cooling schedules) were examined on the dynamic OVSF code allocation problem. The simulation results show that the ASAGA provides reduced code blocking probability and improved spectral efficiency in the system when compared to the CCA and DCA schemes. ASAGA is also tested with its components SA and GA.

Stochastic optimization algorithm based dynamic resource assignment for 3G systems

Orthogonal variable spreading factor (OVSF) codes are widely used to provide variable data rates for supporting different bandwidth requirements in wideband code division multiple access (WCDMA) systems. Many works in the literature have intensively investigated to find an optimal dynamic code assignment scheme for OVSF codes. Unlike earlier studies, which assign OVSF codes using conventional (CCA) or dynamic (DCA) code allocation schemes, in this paper, stochastic optimization methods which are genetic algorithm (GA) and simulated annealing (SA) were applied which population is adaptively constructed according to existing traffic density in the OVSF code-tree. Simulation results show that the GA and SA provide reduced code blocking probability and improved spectral efficiency when compared to the CCA and DCA schemes. It is also seen that, computational complexity of GA and SA are also more than CCA and DCA.

Smart Antenna Based OVSF Code Assignment for WCDMA Networks

This paper presents a new method for dynamic allocation of orthogonal variable spreading factor (OVSF) codes in WCDMA networks where each base station is equipped with an adaptive antenna array (AAA). Previous works about OVSF code assignment problem deal with the code limited case. Here, we investigate the feasibility to turn the problem into the SIR limited case. With our scheme, the new call request is allocated an OVSF code that may be currently used by an active user whose downlink beam has the smallest spatial correlation with the channel vector of the requesting user, as long as desired SIR level is achieved. The performance of the new scheme is justified through computer simulations under different traffic load conditions.

Performance of Adaptive Antenna Array Based Dynamic OVSF Code Assignment for Multipath Propagation and Multicell Environment

Abstract – An OVSF code assignment method using adaptive antenna (AAA) array in WCDMA network has been previously proposed [10] and it has been shown that AAA based dynamic code assignment (AAA-DCA) significantly reduces call blocking probability and increases spectral efficiency in the system when compared to conventional code assignment (CCA) and widely known dynamic code assignment (DCA). In AAA-DCA, OVSF code of an existing user can be reused for the new user as long as downlink weight vector of the existing user and channel vector of the new user have the smallest spatial correlation, and estimated SINR of the new user remains above threshold. However, ideal propagation conditions having a single cell with no multipath propagation were considered in [10]. In this work, performance of the AAA-DCA is investigated under more realistic wireless scenario where there is multicell environment and multipath propagation exists. Signal model and interference analysis to obtain SINR have been presented for this multicell and multipath conditions. Results show that AAA-DCA under these conditions still performs considerably better than CCA and DCA, but causes some degradation in the performance, i.e., 25 % decrease in spectral efficiency, when compared to ideal conditions.