Research Of The Beam-forming Technology In60GHz Wireless Communication Systems

As a variety of high-speed applications with rates over Gigabit per secondgetting into people’s production and life, for example High Definition MultimediaInterface and Gigabit Wireless Local Area Network (WLAN), the modern productionand life demand of high-speed wireless communications services with high quality isbecoming stronger and stronger. Due to the7GHz wide spectrums, low-cost CMOSdevices implements,10W maximum transmit power and other advantages,60GHzwireless communication technology has received considerable attention.Due to severe path loss,60GHz wireless communication encountered difficultiesin the implementation. To solve these problems, we found that beam-formingtechnology has great advantages in improving transmission quality and enhancing thesystem capacity. Besides, beam-forming technology is capable to meet the demandsof low power consumption and low device complexity for60GHz system. At the sametime, the system can effectively reduce network overhead, making beam-formingtechnology one of the key technologies in60GHz wireless communication system.In this paper, beam-forming technology in60GHz wireless communicationsystem is deeply studied. On the basis of comprehensive research of the basicprinciple of beam-forming techniques in60GHz wireless communication systems, thepaper discussed several mainstream beam-forming technologies, including beamcodebook design, code searching algorithms, DOA information accurate estimation.The main work is as follows:Firstly, the beam-forming codebook construction methods of the existinginternational standards IEEE802.15.3c and IEEE802.11ad, as well as an improvedscheme for3c codebook-N phase codebook are studied. On this basis, research of thecode book design based on window functions is conducted. The MATLAB simulationshows the comparison of the performance of various codebooks in aspects of the mainlobe width, the width of the sidelobe, array gain, and soundness. Also, the applicationanalysis is presented.Secondly, code searching algorithms of the existing international standards IEEE802.15.3c and IEEE802.11ad are studied. On this basis, two algorithms with betterperformance are proposed. Thirdly, DOA information accurate estimation method in adaptive beam-formingtechnology is studied, including the MVDR (Minimum Variance DistortionlessResponse) algorithm, the STMV (Steered Minimum Variance) algorithm and MUSICalgorithm. Besides, a new method to improve the performance of MUSIC algorithmbased on STCM (Steered Covariance Matrix) is proposed, and these algorithms areapplied to the DOA information accurate estimation for60GHz signals. TheMATLAB simulation results validate the superiority of these algorithms in DOAestimation accuracy and computational stability.The main achievements of this paper is as follows:Firstly, the codebook design based on weighting function of the window functionare conducted, scheme of codebook based on Chebyshev window function is typicallyresearched, focusing on the impression of the Chebyshev window function parameteron the codebook performance. This research result provides a reference for thepractical application of the codebook based on the Chebyshev window function.Secondly, two new codebook search algorithms-adaptive sector-level codesearching algorithm and progressively sector codebook searching algorithm areproposed based on the existing codebook searching algorithm. Theoretical analysisand MATLAB simulation validate that these two algorithms are significantly betterthan in search complexity than the codebook searching algorithm in standard IEEE802.15.3c and IEEE802.11ad, ensuring success rate close to100%of the search.Thirdly, STMV algorithm is applied to60GHz signal with the advantages ofsmall estimation variance and high spatial resolution. Besides, a new MUSICalgorithm based on steered covariance matrix (STCM) is also proposed, which isapplied in60GHz signal DOA estimation. The MATLAB simulation results validatethe superiority of these algorithms in DOA estimation accuracy and computationalstability. On the consolidated results of the above studies, a new transceiver antennasystem envisaged is put forward, whose transmitter use codebook beam-formingtechnology while the receiver use adaptive beam-forming method for the purpose ofreducing the search complexity and increasing the accuracy of the receiver as much aspossible, thus improve search efficiency without adding feedback burden of thesystem.The characteristics of highly directional energy and requirements of low-power,low device complexity for60GHz signal determine the beam-forming technologybecome one of the key technologies in60GHz wireless communication system. This article gives a comprehensive study of beam-forming technology in60GHz wirelesscommunication system, including switched beam-forming technology based on thecodebook search, and the adaptive beam-forming. On one hand, the analysis of thecodebook based on the window function is presented, and a new code searchingalgorithm with better performance is put forward; On the other hand, several classicaladaptive algorithms are applied in DOA information accurate estimation for60GHzsignals, which has been compared with good results. In conclusion, the researchresults achieved by this article are of great significance for60GHz wirelesscommunication.