Abstract
The codebook-based beamforming for millimeter-wave (mm Wave) communication systems is usually used to compensate the severe attenuation of the mm Wave region. The beam training process based on pre-specified beam codebooks is considered a global optimization problem in 2-D planes formed by the potential beam index. The Rosenbrock algorithm (RA) is adopted to implement optimum beam searching whereas the simulated annealing (SA) algorithm is used to solve the problem of falling into the local optimum, due to the unavailable gradient information of the objective function. However, the RA implements rounding to the integer which leads to the problem of repeated search and beam space discontinuity caused by beam index will impair the powerful local search ability. Thus, in this paper, an enhanced RA based on tabu search and combined with SA algorithm is proposed as an alternative solution for beam search success rate. The proposed algorithm reduces the search times by forbidding the repeat search with tabu table and design of neighbor region. Moreover, to prevent the search failure, the search candidate index is defined to keep the local search ability of the original algorithm and wrap around of beam index is applied to maintain continuity of the search direction. Experimental simulations show that the proposed technique can improve the search efficiency in terms of reduced steps and increase search success rate during the beam training procedure compared to existing techniques.
Highlights
In recent years, to meet the higher requirements on transmission rate and signal bandwidth, millimeter-wave has been widely concerned because of its widely available bandwidth, strong anti-interference ability and short-wavelength [1]
Mm Wave wireless communication has great application value, it faces many difficulties in practical applications due to its serious problems such as small coverage limited by severe path loss, intermittent transmission interrupted by human blockage and extra link budget due to absorption of the atmosphere [2]
Being effective in mitigating the problem of falling into local optimum, it is inevitable for Rosenbrock algorithm (RA) that the intermediate search results are round to the integer to get the beam index, which will cause repeated search problems, considering the clustered structure of beam space immanent to mm Wave, both the correct mapping from beam space to search index, and processing of the index boundary will have a significant impact on the beam search performance
Summary
To meet the higher requirements on transmission rate and signal bandwidth, millimeter-wave (mm Wave) has been widely concerned because of its widely available bandwidth, strong anti-interference ability and short-wavelength [1]. Mm Wave wireless communication has great application value, it faces many difficulties in practical applications due to its serious problems such as small coverage limited by severe path loss, intermittent transmission interrupted by human blockage and extra link budget due to absorption of the atmosphere [2]. To solve this problem, antenna array can be used to obtain remarkable processing gain, this technology can effectively compensate path loss and enhance the signal-noise ratio (SNR) of the receivers [3]. To establish and maintain the directional communication link between transmitter and receiver, beam search at both ends of the link is required, which always is much more time consuming and incurs a big burden on the system in terms of signaling overhead
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