Two kinds of antenna selection algorithm one proposed according to the characteristics of base-station coordination system. One is called aggregate channel frobenius norm antenna selection (ACFAS), another one is indi...
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Two kinds of antenna selection algorithm one proposed according to the characteristics of base-station coordination system. One is called aggregate channel frobenius norm antenna selection (ACFAS), another one is individual channel frobenius norm antenna selection (ICFAS). The object function of antenna selection in ACFAS is based on the aggregate channel frobenius norm of all of the coordinating base-stations and users, while the object function of ICFAS is based on the individual channel frobenius norm of every base-station and user. With the complexity analysis and system simulations, it is proved that the antenna selection algorithms proposed are capable of reducing the complexity, yet at a cost of system capacity lost. So they are suboptimal algorithms.
This paper deals with the channel estimation technology applied to orthogonal frequency division multiplexing (OFDM) systems and proposes a novel method to design the optimal pilot pattern. In this method, first, the ...
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This paper deals with the channel estimation technology applied to orthogonal frequency division multiplexing (OFDM) systems and proposes a novel method to design the optimal pilot pattern. In this method, first, the spacing in the time and the frequency domains between two pilot symbols are determined respectively according to the maximum multi-path delay and Doppler frequency shift. Then, all possible pilot patterns are listed by using the exhaustive method. Finally, the optimal pilot pattern is obtained according to the mean square error between the estimated and the actual channels. In addition, the proposed method is applied to a long-term evolution (LTE) system to verify its correctness and effectiveness, and the superiority of the optimal pilot pattern is verified by simulation curves. From the simulated results, it is found that, as compared with the system using the original LTE pilot pattern, the system using the optimal pattern is of higher BER (Bit Error Rate) performance under the Vehicular Test A channel.
Low complexity schedule algorithm with fewer users was proposed for the downlink of multiuser multiple input multiple output (MU-MIMO) system with limited feedback zero-forcing (ZF) precoding. Taking the lower bound f...
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Low complexity schedule algorithm with fewer users was proposed for the downlink of multiuser multiple input multiple output (MU-MIMO) system with limited feedback zero-forcing (ZF) precoding. Taking the lower bound function of system throughput as the objective function, the proposed algorithm selected users by maximizing the lower bound value. In this way, multi-user diversity gain was obtained and the system throughput increased. According to the fact that feedback linearly increases with the numbers of users, the algorithm's feedback rate was decreased based on the threshold feedback. Simulation results show that the throughput of the system is effectively improved with this algorithm, and with proper threshold feedback the total feedback rate is declined without any negative effects on the system.
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