Space division multiple access (SDMA) uses the advantage of the smart antenna technology to form directional antenna pattern in a cellular. By exploiting the directional antenna pattern for users, SDMA can achieve the spatial orthogonality among users and channel reuse within a cell. Several studies [l], [2] have shown the performance improvement of SDMA in a mobile communication environment. This paper extends the two-folding SDMA blocking probability derivation from [3] and approximately two-folding SDMA approaches from [4]. An approximately model is proposed for three-folding SDMA and the corresponding blocking probability is derived. Analytical and simulation results show that three-fold SDMA increases capacity over the traditional cellular system, which demonstrates the effectiveness of SDMA for resource management.
In this paper we proposed a new approach that clusters mobile users before downlink beamforming and broadens beams and nulls within the beamforming calculation. We first investigate the broadening beamforming scheme to alleviate inaccuracies in DOA estimation. Next we exam how to group the mobile users, with the constraint of separation angle, to enhance downlink beamforming. Simulations show that the downlink beamforming complexity is decreased dramatically with limited performance loss.
Spectrum efficiency is a constant challenge in the design of wireless networks. Space-division-multipleaccess (SDMA) is a promising approach to achieve higher spectral efficiency which reuses bandwidth via multiplexing signals based on their spatial signature. Several different studies have shown that SDMA can effectively improve system capacity in a mobile environment. In this paper, we present a new Markov chain traffic model for a duplicate-at-last (DL) approach [IEE Proceedings on Communication 146 (1999) 303] in two-fold and three-fold SDMA systems. Simplified blocking probability formulations for two-fold and three-fold SDMA are also derived. Simulations based on a common method of spatial separation check for channel allocation in SDMA are presented to evaluate the probability of successfully creating two-fold and three-fold SDMA channels. The simulation, as well as analytical, results indicate that the SDMA system can reduce the blocking probability of the calls and result in more traffic loading than a traditional cellular system. The results also show that our simplified approaches not only can reduce the computational complexity, but can also accurate approximate two-fold and three-fold SDMA performance.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.